Note: Descriptions are shown in the official language in which they were submitted.
'JL~2~79~
This application is a divisional of copending Canadian Application
Serial No. 301,377 filed April 18, 197~ in the name of Mita Industrial
Company, Limited.
This invention relates to a process or electrostatic copying.
More speciEically, it relates to an electrostatic copying process which com-
prises a step of forming an electrostatic latent image corresponding to an
original on a photosensitive member having a photoconductive layer and a
developing step for rendering the latent image visible.
Generally, electrostatic copying processes for forming a copied
image corresponding to an original include a step of forming an electrostatic
latent image corresponding to an original on a photosensitive member having a
photoconductive layer, and a developing step for rendering the electrostatic
latent image visible. The electrostatic latent image-forming step comprises
a step of applying an electrostatic charge to the photosensitive member and
a step of projecting the original image on the photosensitive member. The
electrostatic latent image formed on the photosensitive member in the latent
image-forming step is rendered visible by developing it either directly or
after transferring it to a suitable material (latent image transfer). The
developing step can be performed by various methods, but generally, it is
performed by applying a fine powdery developer ~toner) to the electrostatic
latent image.
Research and development have been done recently on various
aspects of these electrostatic copying processes, especially the electro-
static latent image-forming step and the developing step, and various
improvements have been suggested. None of them, however, are entirely satis-
factory, and various problems still exist which have to be further solved to
obtain copied images of better quality. In particular, the developing step
performed by applying a fine powdery developer to the electrostatic latent
image poses the many problems which are described in detail below with
reference to the accompanying drawings.
Extensive research and development have also been undertaken in
recent years on the electrostatic copying apparatus for the performance of
these electrostatic copying processes, and various improvements have been
suggested. These apparatus, however, have to be improved further to obtain
better copied images, permit easier operation and maintenance, and to render
them simpler in structure and lower in price.
It is a primary object of this invention to provide an electro-
static copying process in which a developing step to be performed by applying
a fine powdery developer to an electrostatic latent image is improved.
According to the present invention, there is provided an electro-
static copying process which comprises
(1~ a step of forming an electrostatic latent image on the surface of
a photosensitive member having a photoconductive layer comprising (a) a step
of applying an electrostatic charge to the surface of the photosensitive
member by a corona discharge device disposed along the path of the photo-
sensitive member and (b) a step of projecting the image of an original
to the charged surface of the photosensitive member by an optical system
including a lamp for illuminating the original in an origina] image exposing
area located along the moving path of the surface of the photosensitive
member downstream of the corona discharge device, thereby to form an electro-
static latent image on the surface of the photosensitive member,
(2) a step of developing the electrostatic latent image by applying a
fine powdery developer to the electrostatic latent image formed on the surface
of the pho~osensitive member by a developing device provided along the moving
path of the surface of the photosensitive member and do~nstream of the image
exposing area, thereby to form a toner image on the surface of the photo-
sensitive member, and
(3) a step of transferring the toner image formed on the surface of the
photosensitive member to a receptor sheet in a transfer station provided
downstream of the developing device along the moving path of the surface of
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the photosensitive member;
wherein for a specified period of time which runs from the time when the
corona discharge device for charging has been deenergized by the completion
of the electrostatic latent image-forming step (1), light is irradiated on
the surface o:E the photosensitive member in an area downstream of the corona
discharge device for charging and upstream of the developing device along the
moving path of the surface of the photosensitive member.
The invention will now be described in greater detail with :~
re~erence to the accompanying drawings, in which:
Figures l-a to l-c are simplified views for
llZO~
illustratirg a gho t image whi.ch occurs during dcvelop--
ment in a known rollir~g contact method;
E`igure ~ is I simplified view of an electros-t~tic
latent image bearing mem~er and a developing apparatus for
illustratirlg the developing step in the electrostatic copy-
ing process in c~ccordance wi-th -this invention;
Figure Z is an enlarged view of a part of a brush
length adju-sting member used in the developing apparatus
shown in Figure 2;
Figure 4 is a diagram showing suitable regions of
distances dl and d2; -;
Figure 5 is a simplified view of an electrostatic ~
copying appara-tus for illustrating the electrostatic copy-
ing process in accordance with this invention; ..
Figure 6 is a simplified view of~ electrostatic
eliminator; :
Figure 7 is a simplified view of an electrostatic
latent image bearing member and. a cleaning device for il--
lustrating a cleaning step.in the electrostatic copying
process in accordance with this invention;
Figure a iS a perspective view9 partly broken ~ ;
away, of the electrostatic copying apparatus in accordance
with this invention;
~igure 9 is a sectional view of the electrostatic
copying apparatus shown in Figure 8~
~ igure 1~ is a simplified partially perspective
view showing an optical system;
Figure 11 is a perspective view, partly ~roken
away, of an upper part of the electrostatic copying apparatus
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shown in Figure 8;
~ igure l? is a perspective ~'ieri showing a support
structure;
Figure 1~ is 1 parti.al perspective view showing
-the state of a lower par-t of the electrostatic copying ap--
paratus shown in Figure 8 7 i11 which a support has been
partly pu.lled out;
Figure 1~ is an exploded view showing a modified
example of a support and elements mounted on itj
Figure 14 is a partial perspective view of that
part of the electrostatic copying apparatu.s shown in ~igure
8 on which the support is mounted;
Figure 15 is a side elevation of -that part of the
apparatus on which a rotary drum is moun-ted;
Figure 16 is a par-tial perspective view of a
paper feed section;
Figure 17A and Figure 17B are front elevations of
the paper feed section shown in Figure 16;
Figure 18 is a simplified view showing a drive
20 . systemj
~ igure 19 is a simplified partial perspective
view for illustrating the drive system
Figure 20 is a simplified view showing electrical
elements of the electrostatic copying apparatus shown in
Figure 8;
Figures 21 -to 24 are circuit diagrams showing
the wire bonding of the electrical elements of the electro-
static copying apparfltus shown in Figure 8; and
~ igure 25 is a partial perspective view showing
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a mechanical sensing element which may be provided to
register the forward end of an original optically pro-
jected on the surface of the rotary drum with the forward
end of a receptor sheet.
DETAI ED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is described in detail with
reference to the accompanying drawings.
Electrostatic copying method
Electrostatic copying processes for forming a
copied image corresponding to an original image, as is well
known, include a zerographic process, an electro-fax pro- -
cess, or a TESI process including an electrostatic latent
image transferring step. All of these processes commonly
include a step of forming an electrostatic latent image
corresponding to an original image on a photosensitive
member having a photoconductive layer, and a developing step
for rendering the electrostatic latent image vi.sible.
Developing step
The developing step for rendering the electrostatic
latent image visible can be performed by various known de-
veloping methods. In recent years, a method involving the
application of a fine powdery developer ~toner) to the -
electrostatic latent image to be developed has been pro-
ferred.
One typical known method within this category -
comprises magnetically holding a fine powdery developer
on the surface of a developer-holding member in the form
of a hollow cylindrical sleeve or an endless belt by means
of a magnet disposed within the developer-holding member,
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and then contacting the surface of the devcloper-holding
member with the surfacc of an imagc-bearing member having
an electrostatic latent imagc formed thcreon (i.e., a plloto-
sensitive member or a receptor membcr to the surface of ~jhich
the electrostatic latent image has been transferrcd) through
the developer, thereby to apply the developer to the elec-tro-
static latent image.
It was first suggested with regard to this known
method to move the surface of the developer-holding member
and the surface of the latent image-bearing member in opposite
directions to each other, thereby successively contacting
the two surfaces with each other. According to the suggestion,
however, the density of the image is low because of a fairly
great slippage between the two surfaces (the difference in
moving speed), and the image obtained is unsatisfactory with
a poor resolving power and a poor reproducibility of halftone.
In an at~empt to overcome this disadvantage, a
"rolling contact method" was suggested which comprises
moving the surface of the developer-holding member and the `~
surface of the electrostatic latent image-bearing member
in the same direction at the same speed, thereby contacting
the two surfaces successively without substantial slippage
(for example, United States Patent No. 4,081,571 which
issued March 28, 1978, or British Patent 1,493,280). This
rolling contact method can afford an image which has a suit-
a61e image density, a high resolving power, and a good
reproducibility of halftone. If a mono-component developer
~so-called carrierless developer) composed of one kind
of magnetic fine powder is used in this rolling contact
,
method, the developer adheres to the surface of the latent
image-bearing member too faithfully according to the po-
tential on the surface. This causes the following dis-
advantages that must be overcome.
(i) the developer adheres thinly to an area which
is spaced from the image area by some distance to form a so-
called ghost image or fringed image.
(ii) The developer adheres thinly to the back-
ground area of the image to cause background fogging.
The ghost image formation and the background fog-
ging are described in detail below with reference to Fig-
ures l-a and l-c. An electrostatic latent image formed on
the surface of electrostatic latent image-bearing member
2 has at its image area I a charge and a potential of a
specific polarity (for example, positive), and because of
the edge effect of the charge on the image area, a potential
of an opposite polarity (for example, negative) in the -
surrounding of the image area. Accordingly, the potential
pattern of the electrostatic image shown in Figure l-a is
known to be as shown in Figure l-b. If the developer com-
posed of a single magnetic fine powder is cuased to ap-
proach the electrostatic latent image, the charge of the
electrostatic latent image induces a charge of an opposite
polarity in the developer, and therefore, the development
of the latent image proceeds by the Coulomb's attractive
force acting between the two charges. Since the developer
is magnetically held on the surace of the developer-hold-
ing member, the developer, upon contact with the electro-
static latent image, adheres to that part of the latent
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1~2~ 30
image which has a potential above a certain value ~+ y
V) that begins to exert a Coulomb's attractive force
larger than the magnetic holding force of the developer
holding member on the developer, irrespective of the
p~olarity of the potential on that part. Thus, when the
surface of the electrostatic latent image-bearing member
is contacted successively with the developer from right to
left in Figure l-a (in the direction shown by arrow A in
Figure l-a), the developer adheres to the portion of image
area I, and thinly to part G which is upstream of the image
area by distance x. Consequently, as shown in Figure l-c,
a ghost image is formed at part G upstream of image area I.
A potential above the certain value (+ y V) exists on part
G', spaced downstream of the image area I by distance x
until the development of image area I ends. When the de-
velopment proceeds and the potential of the latent image
in image area I decreases as a result of the adhesion of the
developer to image area I, the potential on part G' de- ~`
creases to below + y V, and therefore, a ghost image does
not substantially form on part G' downstream of the image area
I.
In an ordinary electrostatic copying process in
which an electrostatic latent image formed on a photosensitive
member is directly developed, the photosensitive member is
fatigued as a result of forming an electrostatic latent image
in the previous cycle, and it is extremely difficult, if
not impossible, to remove the fatigue completely before
the beginning of the new cycle. Accordingly, the photo-
sensitive member (i.e., the electrostatic latent image-
bearing member) has some residual potential caused by the
fatigue in the previous cycle in addition to the potential
of the electrostatic latent image to be developed. General-
ly, the residual potential tends to increase gradually
as a result of repeatedly using the photosensitive member
with a short recess between cycles. In the case of using
an ordinary two-component developer, the developer is
biased to a specified potential of the same polarity as
the residual potential and thus cancels the residual po-
tential. In contrast, in the rolling contact method, the
developer adheres to the surface of the electrostatic
latent image-bearing member ~oo faithfully according to the
surface potential of the image-bearing member, and in
particular, a mono-component developer is attracted by a
potential of any of the positive and negative polarities.
Hence, if a bias voltage is applied, the adhesion of the
developér is increased. Mainly for the above reason, the
developer adheres also to an area having the residual po-
tential, and the background fogging of the non-image area
gradually increases as the number of copying operations
increases.
The present inventors have newly found that if
the surface of the developer-holding member and the surface
of the electrostatic latent image-bearing member are con-
tacted with each other successively by being moved in the
same direction at somewhat different speeds in a developing
station, where the surface of the developer-holding member
is contacted with the image-bearing member through the
developer, the developer which adheres wea~ly to the
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surface of the image-bearing member and causes ghost
image formation and background fogging can be wiped off by
exerting the mechanical brushing action on the developer
held magnetically to the sur:Eace of the developer holding
member without reducing the density and resolving power of
the image and the reproducibility of halftone; and that
consequently, the desired image free from ghost image for-
mation and background fogging can be obtained.
Specifically, the present inventors have newly
found that in an electrostatic latent image developing process
which comprises magnetically holding a fine powdery developer
on the surface of a developer holding member by means of a
magnet disposed within the developer-holding member, then
contacting the surface of the developer-holding member
with the surface of an electrostatic latent image-bearing
member through the developer, and thus applying the developer
to the electrostatic latent image to develop it, an image
having a high image density, a high resolving power and a `
superior reproducibility of halftone and being free from :
ghost image formation and background fogging can be obtained
in a devloping zone by moving the surface of the developer-
holding member and the surface of the electrostatic latent
image-bearing member on contact with each other in the same
direction at such speeds that a speed difference of about
20 m/minute > IVl - V2¦>0 m/minute is provided between the
moving speed Vl of the surface of the developer holding
member and the moving speed V2 of the surface of the electro- -
static latent image-bearing member.
The speed difference differs somewhat according,
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for example, to the potential of the electrostatic latent
image to be developed or the characteristics o the de-
veloper. It is generally about 20 m/minute >¦Vl - V2¦>
about 1.0 m/minute, preferably about 20 m/minute >
¦Vl - V2¦> about 3.5 m/minute. Especially, the Vl- V2
is preferably a positive value.
This new finding is described in more detail with
reference to Figure 2. Electrostatic latent image-bearing
member 2 having an electrostatic latent image formed on its
surface, which is, for example, a rotary drum having a
photoconductive layer of selenium or cadmium sulfide is
rotated in the direction shown by arrow B (clockwise dir-
ection in Figure 2). In developing section 4, the electro-
static latent image formed on the surface is developed by
a developing device generally shown at 6. The electrostatic
latent image to be developed is formed on the surface of
the latent image-bearing member 2 upstream of developing
station 4 by any method known to those skilled in the
art.
Developing device 6 includes developer-holding
member 8 to be rotated, magnet 10 disposed within the member
8 and developer supplier 14 for supplying developer 12 to
the surface of developer-holding member 8. Developer-
holding member 8 may be any desired material which can
magnetically hold the developer supplied from supplier
14 to the surface of the developer-holding member by the
action of magnet 10 and can be contacted with the surface
of electrostatic latent image-bearing member 2 through the
developer in developing station 4. For example, it may be
.~
made of an endless belt. A suitable developer-holding
member is made of a hollow cylindrical sleeve and can be
rotated in the direction of arrow C in Figure 2 ~in the
counterclockwise direction in Figure 2). Furthermore,
when the developer used is a mono-componcnt developer
composed of a conductive or semiconductive magnetic fine
powder (the developer will be described in detail herein-
below), a developer-holding member composed of a main
body of a nonmagnetic metallic material and an insulating
coating formed on the surface of the main body is used
suitably. Preferred insulating coatings are, for example,~-
organic insulating coatings such as polystyrene or poly-
ethylene terephthalate, inorganic insulating coatings
such as aluminum oxide, or composites of these, which
have at resistance of at least 103 ohms/cm2, especially
at least 105 ohms/cm2.
Magnet 10 to be disposed within developer-
holding member 8 may be of any type which has the action
of magnetically holding the developer onto the surface of
developer-holding member 8. When developer-holding
member 8 is a hollow cylindrical sleeve as shown in the -`
drawings, the magnet is preferably a stationary roll-like
permanent magnet having a plurality ~for example, 8) of
magnetic poles which are located on its periphery and
alternately have opposite polarities. Preferably, as
shown in ~igure 2, such a stationary roll-like permanent
magnet is generally fixed within the developer-holding
member such that one of the magnetic poles is positioned
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upstream in the rotating direction of the developer-hold-
ing member by angle ~ with respect to position P at
which the surface of electrostatic latent image-bearing
member 2 approaches the surface oE developer-holding member
8 most closely. If, however, developer-holding member 8
is roated at a fairly high speed, it is sometimes preferred
to position one of the magnetic poles of the permanent
magnet at position P at which the surface of developer-hold-
ing member 8 approaches the surface of the electrostatic
latent image-bearing member most closely. When developer-
holding member 8 is rotated at a fairly high speed, the
developing station Ithe contact zone between the developer
and the surface of image-bearing member 2) must be increased
by bringing the surface of image-bearing member 2 closer
to the surface of developer-holding member 8 to maintain
the developing time (the time during which the surface of
the electrostatic latent image-bearing member is in contact
with the developer). If one of the magnetic poles is positioned
at a point somewhat farther upstream of position P in this
case, the surface of electrostatic latent image-bearing
member 2 contacts the developer even at an intermediate
point between magnetic poles, and development occurs also
at this point.
The developing device 6 further includes a brush
length adjusting means such as a doctor blade for control-
ling the thickness of the developer layer which has been
supplied to ~he surface of developer-holding member 8 from
developer supplier 14 and held there magnetically. The
brush length adjusting means can be made up of, for
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example, member 16 which is adjustably secured to side
wall 14a of supplier 14 that is positioned do~nstream in the
rotating direction of developer-holding member 8. Member
16, as is clearly shown in Figure 3, tapers toward its free
end which is positioned near the surface of developer-hold-
ing member 8 at a point at which one of the magnetic poles
of nlagnet 10 is situated in its vicinity. Preferably, the
thickness of the free end is more than 0 mm and up to
0.5 mm. The angle ~ defined by both side surfaces of the
10 free end is not more than 15, preferably not more than
10.
Preferably, member 16 constituting the brush
length adjusting means is disposed near the surface of
developer-holding member 8 somewhat upstream of one of
the magnetic poles of magnet 10 in the moving direction
of the surface of developer-holding member 8. According
to this construction, because of the form of the line of
magnetic force generated by magnet 10, the developer within
developer supplier 14 is not urged against member 16 and
20 does not solidify there. Accordingly, a layer of the de-
veloper having a good surface condition is formed on the
surface of developer-holding member 8, and the toner image
developed increases in quality. It is also preferred that
the tip of side wall 14b which forms one edge of the de-
veloper outlet of developer supplier 14 and is positioned
upstream in the rotating direction of developer-holding
member 8 should be disposed somewhat upstream of one of
the magnetic poles of magnet 10 in the moving direction
of the surface of developer holding member 8. According
to this embodiment, the developer is not carried to the
outside tip portion of side wall 14b of the de~eloper
supplier because of the form of the line of magnetic force
generated by magnet 10.
Distance dl between the free end of member 16
and the surface of developer-holding member 8, as will be
described hereinbelow, is closely related to distance d2
between the surface of developer-holding member 8 and electro-
static latent image-bearing member 2 at position P at which
these surfaces approach each other most closely. Generally,
distance d1 is 0.15 mm < d1 < 0.5 mm, especially 0.2 mm < d
< 0.45 mm. If distance dl is too small, a sufficient
amount of the developer cannot be supplied to developing
station 4. Conversely, if distance dl is too large, the
layer of the developer held on the surface of developer-
holding member 8 becomes thick, and the developer which is
situated at the outermost position is held by a weak holding
force. Consequently, the scattering of the developer occurs
at developing station 4, and the image developed is fogged.
On the other hand, distance d2 between the surface of
developer-holding member 8 and the surface of electrostatic
latent image-bearing member 2 at position P at which they
approach each other most closely is closely related with
the distance dl described above. Generally, the distance
d2 is 0.6 mm s d2 > dl, preferably 0.55 mm > d2 > dl.
According to the information which the present
inventors have obtained through research and experimental
; work, the distances dl and d2 are preferably within the
area defined by a line connectlng the four points
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(0.15, 0.25), (0.5, 0.6), (0.25, 0.6) and (0.15, 0.5) in
a graphic representation of Figure 4 in which dl (mm)
is on the axis of abscissas and d2 (mm) is on the axis
of ordinates, and especially preferably within the area
defined by a line connecting the four points (0.2, 0.3),
(0.45, 0.55), (0.25, 0.55) and (0.2, 0.5).
Distance d3 from the forward end of side wall
14b located upstream in the rotating direction of the
developer-holding member, which defines one edge of the
developer outlet of developer supplier 14, to the surface
of developer-holding member 8 is generally 5 mm ~ d3 > 1 mm,
preferably 3 mm > d3 > 2 mm.
Developer 12 is suitably a known mono-component
developer composed of a single conductive or semiconductive
fine powder with a particle diameter of 5 to 30 microns,
preferably 8 to 15 microns which is obtained by coating a
fine powder of iron, cobalt or nickel, or an oxide of such a
metal, or an alloy of such a metal, or a mixture of these
with a resin such as an epoxy, styrene or olefin resin, or
further adding a suitable coloring agent such as carbon
black.
In developing device 6 described above, the
surface of the developer-holding member within developing `~
station 4 is contacted with the surface of electrostatic
latent image-bearing member 2 through developer 12 retained
on its surface. It is important that the two surfaces should
be contacted with each other through developer 12 in the
manner to be described below.
Electrostatic latent image-bearing member 2 is
ro~ated at a fixed speed in the direction of arrow B
(that is, in the clockwise direction in Figure 2), and
developer-holding member 8 is rotated at a fixed speed
in the direction of arrow C (that is, in the counterclock-
wise direction in Figure 2). ~lence, the surface of image-
bearing member 2 and the sur:Eace of the developer-holding
member are moved in the same direction in developing station
~ where the surface of developer-holding member 8 is con-
tacted through the developer held on it with the surface of
image-bearing member 2. These members are moved at such
speeds that the moving speed Vl of the surface of developer-
holding member 8 differs from the moving speed V2 of the
surface of image-bearing member 2 as follows:
about 20 m/minute >IVl - V2¦> 0 m/minute.
As described in detail with reference to Figures
l-a to l-c, when a mono-component developer composed of a
single type of magnetic fine powder is used in the known
rolling contact method which involves moving the surface
of developer-holding member 8 and the surface of image-bear-
ing member 2 at substantially the same speeds (Vl - V2 = 0),
a ghost image is formed and the background is fogged,
because the developer adheres to the surface of image-
bearing member 2 too faithfully according to the potential
pattern of the surface. If, however, the surface of
developer-holding member 8 and the surface of image-bear-
ing member 2 are moved in the same direction at different
speeds as described above, the developer which adheres
thinly to the nonimage area with a weak adhering force
and is likely to cause ghost image formation and background
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fogging is scraped off by the mechanical brushing action
of the developer held magnetically on the surface of
developer-holding member 8. The scraping of the developer
is done without substantially reducing the density and
resolving power of the image area and the reproducibility
of halftone, and the image obtained is free from ghost
image Eormation and background fogging. If the speed dif-
ference (Vl - V2) is larger than about 20 m/minute~ the
mechanical brushing action of the developer magnetically
held to the surface of developer-holding member becomes
excessive, and the resulting image has a low density, a
poor resolving power, and a poor reproducibility of half-
tone. Or because the developer applied to the developing
station by the rotation of developer-holding member is in-
sufficient, the density of the resulting image decreases.
Preferably, the speed difference (Vl - V2) should
be a positive value. If the speed difference (Vl - V2)
is a negative value (in other words, of the moving speed
Vl of the surface of developer-holding member 8 is smaller
than the moving speed V2 of the surface of image-bearing
member 2), the amount of the developer supplied to developing
station 4 by the rotation of developer-holding member 8
tends to be insufficient. Specifically, therefore, it is
preferred to render the moving speed Vl of ~he surface of
developer-holding member 8 somewhat larger than the moving
speed V2 of the surface of the image-bearing member 2.
The optimum speed difference Vl - V2 differs somewhat
according to the magnitude of the potential on the electro-
static latent image to be developed, the characteristics
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of the developer (the sensitivity of the developer to
the potential), the magnetic holding power of the magnet
for the developer, the moving speed (i.e., the developing
speed) of the surface of image-bearing member 2, etc. In
the development of an electrostatic latent image in an
ordinary electrostatic copying process, the speed difference
is about 20 m/minute to about 1.0 m/minute, preferably about
20 m/minute to about 3.5 m/minute.
~xample
In an apparatus of the type shown in Figure 2, a
rotary drum made by vacuum-depositing selenium on the
surface of a cylindrical aluminum support with a diameter
of 120 mm was used as an electrostatic latent image-bear-
ing member. The surface of the rotary drum was uniformly ~'
charged by positive corona discharge. An original image was
projected on the drum surface charged to a fixed positive
potential (Vs) to form an electrostatic latent image.
A toner composed of a mono-component magnetic powder
was supplied from a developer supplier to the surface of
a developer-holding member made of a non-magnetic cyiindrical
sleeve having a magnet disposed inside, thereby to form
a layer of the toner on the surface of the sleeve. The
strength of the magnetic force on the surface of the sleeve ~;
was about 1,000 Gauss. The particle diameter of the toner
was adjusted to 5 to 30 ~ to obtain a good quality image
and prevent the scattering of the toner particles at the
time of transfer. The cylindrical sleeve was rotated at
a suitable peripheral speed to convey the toner magnetically
attracted to the surface of the sleeve to a developing
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position.
Thus, the toner was applied to the electrostatic
latent image to form a toner image. The toner image formed
by development was then transferred to a receptor sheet
and fixed on it under pressure.
The residual charge on the rotary drum after the
transferring operation was removed by t.he irradiation of
light, and the residual toner was removed by the developing
device itself or by a suitable cleaning device equivalent
to the developing device.
In the formation of the electrostatic latent image,
the surface of the rotary drum was charged so that its
surface potential Vs would become about 700 V at the time
of development. Then, a light image and a dark image of
the reflecting light from an original which had been ir-
radiated with light (adjusted to about 4S0 W) from a halogen
lamp with a rating of 700 W (the length of the light emit-
ting portion was about 280 mm) were projected on the surface
of the rotary drum using two reflecting mirrors and an in- '
mirror lens. The reflecting ratio of the reflecting mirrors
was more than about 95%, and the lens had an F value of 5.3
and a focal length of 235 mm.
The cylindrical sleeve used in the development
was a hollow cylindrical body of aluminum with a diameter of
32.4 mm, and an aluminum oxide coating obtained by anod- `
ization at a low temperature was formed on the surface of
the sleeve. The hollow cylindrical body was grounded
during use. The shape of the developer supplier, the
brush length adjusting member and other parts are as
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illustrated in Eigure 2.
[A] Distance (dl) between the surface of the
cylindrical sleeve and the end of the brush
length adjusting member, and distance (d2)
between these surfaces at a point where
they come closest to each other:
Experiment was per:Eormed under the aforesaid
experimental conditions while varying dl and d2, and the
results shown in Table 1 were obtained.
- 22 -
. . ,
~ f L~
~ _____ _ __ _ _ _ ~ _
.. . ... .
~o ~ ~ X
. ..
o ~ ~ ~ ~ ,
. ~ ~
t ~ o ~ ~ ~ ~
~ . .~ ~
o <~ O O <~ <~ ~ h ~
.. _ .. . . __ _ _ O ~
~ `~` ~ ~ O O ~ ~ ~ ~
_ _ _ _ a~
<I (~ ~) O O <~ <¦ x 1-1 h
~31------------- ----_ ~
E~u~ <~ (~) (~) (~ O O <I ~1 x e e 'ed e
__ _ _ _ _ h h h h
N <~ ~) (~) (~ (~) O O <I ~I X O O ~ ~_ :
_ __ . _
.,~, x ~I O O O O O ~ ~ x x < ~( )Ç ~ ~
- - - - . - - - -
o ~ x x ~ ~I ~ ~ _ ~ x x x
~ ~ Lr~ u~ n ~ n
~( _I N N ~) ~) ~ ~ Ir~ Ir~ ~O ~O r~
~1 o o o o o o o o o o o o o
~ __ _ _ ___
,~
The results obtained are discussed brieflybelow.
~ hen d2 is shorter than dl + 0.05 mm, the thick-
ness of the toner layer on the surface of the sleeve is
larger than d2. Accordingly, the toner is compressed and
solidified in the developing zone, and the development of
the electrostatic latent image becomes poor. When dl is
shorter than 0.1 mm, the toner density of the toner layer
on the sleeve surface is low, and the density of the toner
image does not increase. Furthermore, when dl is less than
0.1 mm~ mechanical accuracies, for example in the eccentricity
of the cylindrical sleeve or the rotary drum, are rigorously
required. When within the range of dl i 0.1 mm, d2 is ~ore
than dl + 0.45 mm, d2 is far larger than dl, and the toner
layer does not make sufficient contact with the photosensi-
tive surface of the drum, and no useful toner image can
be obtained. ~'hen the distance d2 between the surface of
the' rotary drum and the surface of the cylindrical sleeve
exceeds 0.7 mm, good results cannot be obtained. When d2
is larger than 0.7 mm, the toner layer to be held magne-
tically onto the surface of the sleeve must necessarily be
increased in thickness. When the thickness of the toner
layer increases, the magnetic force exerted on the toner
particles which will contact the rotary drum is weakened. -
Accordingly, the electrostatic force between the electro-
static latent image and the toner increases to increase
fogging. At the same time, the rotation of the sleeve
causes the scattering of the toner particles to soil the
copying machine. When the distance dl is maintained
- 2~ -
.
,
~:~l2~
constant, the density of the toner layer is determined
according to the flowability and particle diameter of the
toner, the interpole distance of the magnetic roll, the
magnetic flux intensity of the magnet, etc. Ilence, the
distance dl should be determined according to these con-
ditions.
[b] Relation between moving speed V oE the
surface of the cylindrical slee-~e and
moving speed V2 of the surface of the
rotary drum:-
(a) In consideration of the results obtained in[A], the above experiment was performed while maintaining
dl = 0.25 mm and d2 = 0 4 mm and the peripheral speed V2
of the rotary drum at 11 m/min. The cylindrical sleeve
was moved at varying peripheral speeds V2 in the same direc-
tion as the rotating direction of the rotary drum. The
results obtained are shown in Table 2.
_ 25 -
~ !
- " ~
09~
. ~_,~. __ __
~ C~ X X X X ~ O .,
~ _ _ _ _ ,
~ a a a a o o
_.... ._ ~ _ ~
~ a a o o o o
. . . _ _ _ _
N a o o o o o
~ _ . . .
~, o o o ~ ~ o
. .... _ _ _ .
00 o o ~ ~ ~ o
. . _ _ . _ .
. . ~ o ~ ~ ~ ~ o
o o o o a ~ ~ ~-
. _ _
~ a a a a x x
. . _ .
O X X X X X X
.._ . . _ _
~1 O a a ~ a a x
~ ~
~1 . . _ . .
:`'
O o o o o o X
. __ . .-.
o ~ a ~ a
o _ X X X
. _ _ __ _ _
X X X X X X ;-~
~ E ,. / _ _
c.c ~ a ~
a~ ~ ~ v, ~ ~ O ~ ~ ~
4-1 ~ ~ h O O O O O O
r~ ~ ~,c ~ ~ ~ ~ ~ ~ ~
ar~ :-
. / ~C_ _ _ _
When the peripheral speed V2 of the rotary drum
is ll m/min., a toner image of good quality is obtained
within the area of 19.8 > Vl - V2 > 2.41, or -2.05 > Vl - V,
> -9.6. ~hen Vl is low, non-uniformity in image tends to
occur owing to the non-uniformity of the speed. Hence, a
special care must be taken to minimize the non-uniformity
of the speed. When Vl is 0, the toner is not supplied to
the developing zone, and therefore, an image cannot be
obtained. When the peripheral speed Vl of the cylindrical
sleeve is equal to the peripheral speed V2 of the rotary
drum (Vl - V2 = p), the rotary drum and the cylindrical
sleeve are brought into rolling contact with each other
through the toner layer, and toner adhesion occurs very
faithfully to the electrostatic latent image. However,
the residual potential on the rotary drum coated with photo-
sensitive selenium for example is high, too faithful a
development is not desirable. The resistivity of the toner
shown in Table 2 is a value obtained when a DC voltage of
50 V is applied to the toner layer having a thickness of
1.5 mm. The density of the image decreases with increasing
resistivity of the toner. However, the image becomes hard
in tone, and increases in sharpness.
(b) The toner image obtained by forming an
electrostatic latent image varies according to the maximum
potential of the surface of the rotary drum (i.e., the
maximum potential Vs of the electrostatic latent image
formed) and the resistance (R) of the toner. To make sure of
this, the relation of the toner image to the Vs and R values
at Vl - V2 = 3.5 m/min. was examined. The results are shown
in Table 3.
::$
: .
~ ----------- ----
o l l l l l l l x x
~ ------- - --
O l l l l l l X X X
--- --- - - - - - -
o l i l x x x x x x ~:
-- - ~ - - - - - -
. ~ l l x ~ ~I
o x x x ~ ~ ~ ~ ~i <i
~ -~ x x x ~ o ~ ~ ~ ~i
r9~ to` x ~ ~ ~i ~ ~ ~ o x
E~ _ . ___ . _ _ _ _ _ ..
~D ~i ~I ~ o ~ ~ ~ ~ x
---------------- ---- ----
n ~ O O ~ ~ O O <i X "
o o o ~ ~ o <i ~ x x
:
/ --- -- --
` /
/
/
~l ~ ~ r~ co C~
/ ~ , o o O o O o O O o
/- ~ -- - - - :`
_ 28 -
' . ,
/~ ~
~Z~90
When the surface potential Vs reaches 800 V,
a ghost image begins to appearO l~hen it exceeds 1000 V,
the ghost image increases very much, and the resulting
image is uselessO When the resistivity of the toner
exceeds 1014 ohms-cm, a sufficient iMage density cannot
be obtained unless the surface potential is increased
extremelyO ~oner particles having a lo~ resistivity
adhere to the electrostatic la-tent image in an increasing
a~ount, and therefore~ the fog density increases~ For
this reason, a good image cannot be obtained unless the
surface potential is reducedO When the surface potential
is less than 200 V, the density of the image decreases
extremely (the reflective image density is less than 0O5)~
and the image obtained is not feasibleO ~ven when the
surface potential is less than 200 V and the resistivity
of the toner is less than 106 ohms-cm, the density of the
image can be increased by weakening the magnetic force
of the developer-holding memberO However, since the surface
potential of a bright area of the image (the residual poten-
tial) is almost constant, the amount of -the toner adhering
to t~e residual potential increases, and the resulting
image has an e~tremely high fog densityO
Electrostatic copying process ~hich involves
developing an electrostatic laten-t image formed
on a photosensitive member, and transferring
the developed image -to a receptor sheet (the
toner image-tra sferrin~ step~ _ _
As described hereinabove, various forms of electro-
static copying process exist for producing a copied image
3 corresponding to the image of an originalO In recent years,
there has been an increasing demand for "plain paper copying
- 29 -
(PPC)" by which a copied imag2 is formed on a sheet of
plain paper (including papers somewhat processed but
being substantially equivalent to plain paper)~
~he electrostatic copying process for producing
a copied image on plain paper generally includes a step
of forming an electrostatic latent image corresponding
to an original image on a photosensitive memberg a develop-
ing step for applying a fine powder developer (toner) to
the resulting electrostatic latent image to render it
visible, a step of transferring the toner image on the
photosensitive member after the transferring, and a cleaning
step for removing the toner remaining on the photosensitive
member after the transferringO
Referring to ~igure 5, the electrostatic copying
process is briefly described belowO ~he photosensitive
member (io eO ~ the electrostatic latent image-bearing ~-
member) 2 which is in the form of a photos~nsi-tive drum
to be driven in the direction of arrow B first undergoes
the action of corona discharge d.evice 20, and a static
charge is applied to the surface of photosensitive member
2 (the charging step)O ~hen, the image of an original
(not shown) is projec-ted onto the surface of the photo-
sensitive member 2 by an optical system 22 ln an original
image exposing zone located downstream of the corona dis-: :
charge device in the rotating direction of photosensitive
member 2 (the step of exposing an original image)O Con-
sequently, an electrostatic latent image corresponding to
the original image is formed on the surface of photosensi- :
tive member 2 (the electrostatic latent image-forming step)O
- 30 -
.. . . .
.
..
.
;. : ' .
-
Then, by a developing device G desirably of the -type
shown in Figure 2, a .fine po~AIdery developer (toner) is
applied to the elestrostatic latent image on the sur~ace
of photosensitive member 2 to develop the latent image
into a toner image (-the developing step)O Then, the -toner
image on photosensitive member 2 is transferred in trans-
ferring zone 24 to a receptor sheet fed from a receptor
sheet supplying section composed, for example, of paper
supply cartridge 260 lhe receptor sheet having the toner
image transferred to its surface is sen-t -to fixing device
2~ constructed, for e~ample, of a pair of press rollers,
and the toner image is fixed to the receptor sheet under
pressure, after which the sheet is discharged onto receiv-
ing tray 30 (the fixing step)~ In the meantime, the
photosensitive member, after the toner 1mage formed on
it has been transferred to the receptor sheet, is irra-
diated with electrosta-tic elimina-ting, lamp 32~ whereby
the residual charge on the photosensitive m~mber is re-
moved (the charge eliminating step)O ~he toner remaining
on the photosensitive member is removed (the cleaning step).
~oner ima~re trans_errin~ ste~
The toner image transferring step in the electro-
static copying process summarized above is conveniently
carried out generally by bringing the surface of photo-
sensitive rnember 2 into close contact with the surfaceof the receptor sheet in transferring zone 24, and applying
a discharge current to the receptor sheet from its back
using corona discharge device 36 for transfer~
The toner image transfer method described,
- 31 -
~, ~
~Z~1~9~
however~ has the àefect that scme distortion occurs in
the toner image transferred onto the receptor shee-tO
The present inventors e~tensively stucli.ed -the distortion
of the toner image, and obtaille~l the following informationO
In the conventional method for toner image transfer, the
receptor sheet to be fed into -the transfer zone ~irst
passes between shield side plates of corona discharge
device 36~ and is then brought into close contact wi-th
the surface of photosensitive rnember 20 Accordingly,
be~ore the surface of photosensitive member 2 comes into
close contact wi-th the surface of the receptor sheet, both
surfaces are influenced by the discharge current of dis- : -
charge device 350 As a result, the toner on the surface
of photosensitive member 2 or on the surface of the receptor
sheet undergoes vibration between the two surfaces and is
thus scatteredO Scattering of the toner, in turnl causes
the distortion of the toner image transferred to the
receptor sheet~
On the basis of ~his information~ the presen-t
inventors have found that the distortion of the toner .
image on the receptor sheet can be effectively prevented
by bringing the surface of photosensi-tive member 2 in-to
close contact with the surface of the receptor sheet as
soon as, or before, the receptor sheet passes between the
shield side plates of corona discharge device 36 (that is
to say, before the receptor shee-t enters a zone where it
is influenced by the discharge current), and thereby
physically preventing the vibration and scattering of the
toner particlesO
- 32 -
~Q~
The close contact oi` tho l~face oi photosensi-
tive member 2 with the surface of the receptor sheet
before the passing oi t.le reccptor sheet bet~,ieen the
shield side plates of corona discharge devic- 36 can be
acl.lieved, for example, by pos:itioning the ends of the
shield side plates (especially -the one which i5 more up-
stream in the moving direction of the receptor sheet)
of corona discnarge clevice 35 in proximity to the
surface of photosensitive member 2, and properly disposing,
with respect to corona discharge device 36, that part of
the receptor sheet conveying path which is situated up-
stream of corona discharge device 36 in the moving direc-
tion of the receptor sheet (the path is formed by receptor
sheet guide plate 38, etcO a.Lthough this is not shown in
detail in the drawings), as shown in ~igure 50
Fixing step
The receptor shee-t closely co~taining the
~surface of photosensi.tive member 2 in the transfer step
is separated from the surface of photosensitive member 2 ~
by such a means as peeling nail 40 at a point downstream
of transfer station 240 It is then conveyed to receiving
tray 30 through fixing device 28~ -
In the step of conveying the receptor sheet
from transfer station 24 to receiving tray 30, the receptor
sheet collects static char~ge at the time of transferring
or fixing the toner image by fixing device 280 ~he electro-
static charge may cause the recep-tor sheet to turn upward
from the surface of guide plate 42 in the transfer path
from transfer station 24 to fixing device 28, and thus
- 33 -
.' ' ' '' - ' ' ,
'
/ ~
- "
paper jamming occursO Or the elec-trostatic charge causes
the receptor sheet 'o turn upwa:rd at the ti~le of dis-
charge into recelv-ing tray 30; and the receptor shc-et
canno-t be properly discharged onto receiving tray 30a
The present inven-tors have found t~at if electro
static eliminator 44 iS provided above receptor sheet
guide plate 42 in the receptor sheet conveying path between
transfer station 24- and fi~ing device 2~, the action of
eliminator 44 urges the receptor sheet against the s~rface
of guide plate 420 Thus9 the receptor sheet is conveyed
in good condition without paper jamming and other troublesO
If electrostatic eliminator 46 is provided above the end
of the receptor sheet conveying path (io eO ~ above the
inside end of receiving tray 30), the action of eliminator
4-6 urges the receptor sheet downward~ and thus prevents
it from turning upward at the time of discharging onto
receiving tray 300 :.
Electrostatic elimina-tors 44 and 46 ma~ con- ~.
veniently be "spar~less electrostatic eliminators" which
are obtained by processing an electrically conductive
cloth or resin plate9 a cloth having fine electrically
conductive fibers or fine metal wires interwoven or a
film having a conductive fine powder dispersed in the resin
into a saw teeth form so as to permit a corona discharge
between the sharp edges of the saw teeth and a charged bodyO
Cleanin~ step
After the transferring of the toner image formed
on the surface of photosensitive member 2 to the surface
of the receptor sheet in transfer station 24~ the toner
_ ~L~ _
remaining on the s~rface of pnotosensitive .~e~ber 2 can
be removed by various methocls, for ~arliple~ by li~;htl~
rllbbing the s.lrfacè of photosen~ tive drui(l 2 with a
rotar~ fur brushO Preferably, cLea!ling can be perfor~ed
b~ contacti~g a hollow cylincl:rical or endless belt-like,
developer-holding member havirg a toner magne-tically held
to its surface by the action of a stationary permanent
magnet disposed in its inside~ with the surface of photo-
sensitive member 2 through the developer layer on the
developer-holding member while providing the largest
possible difference in speed between them (therefore~
it is preferred to move the surface of the developer-
holding member in a direction opposite to the moving
direction of the surface of pho-tosensitive member 2)o
Referring to Figure 7, cleaning device 34 which
performs the cleaning method described above includes
developer-holding member 50 preferably of a hollow
cylindrical form, and stationary permanent magnet 52
disposed within ito Preferably, developer-holding member
50 ar.d magnet 52 are equivalen-t to developer-holding
member 8 and magnet lO used in developing device 6 des- -
cribed hereinabove with reference to Figure 2~ The
developer-holding member 50 magnetically holding toner
12 (same as -the toner used for development) on its surface
by the action of magnet 52 is ro-tated in the direction of
arrow D (in the clockwise direc-tion in Figure 7) so that
its surface moves in a direction opposite to the moving
direction of -the surface of photosensitive member 20 Thus,
the surface of developer-holding member 50 is continuously
- 35 -
~Z~9~
contacted with the surface of photosensitive member 2
through developer layer 12. Brush length-adjusting
member 56 secured to frame member 54 is provided at a
position downstream by a fixed distance from position Q
~at which the surface of developer-holding member 50 is
closest to the surface of photosensitive member 2) in
the rotating direction of member 50. The end of brush
length-adjusting member 56 is close to the surface of
developer-holding member 50, and serves to remove the
excess of the developer from developer-holding member 50
and adjust the length of the developer brush on developer-
holding member 50 to the desired value. Frame member 54
has receptacle 58 removably secured to it. Receptacle 58
is positioned beneath brush length-adjusting member 56 and
is adapted to receive the developer which has been removed
from the surface of developer-holding member 50 by the
action of brush length-adjusting member 56 and fallen
downward.
In cleaning device 34, the surface of developer-
holding member 50 is moved in a direction opposite to the
moving direction of the surface of photosensitive member 2.
Hence, developer layer 12 magnetically held on the surface
of developer-holding member 50 slides over the surface of
photosensitive member 2 at a fairly high relative speed.
The mechanical brushing action of the developer thus causes
the remaining toner on the surface of photosensitive member
2 to be removed from it~ and the toner is magnetically
J attracted to the surface of the developer-holding member.
This action is more effective as the magnetic action of
- 36 -
~/
,
~ , ,
~ ~
~%~o~o
magnet 52 is larger and the rotating speed of develo~)er-
holding member 50 is higher (i~e~. the relative speed
of the surface of mernber 50 and member 2 is larger)O
~lhF~ developGr la~er on developer--holdin~ member 50 ~lhich
has become excessive as a result of the adhesion of the
developer remove-l from the surfacc of photosensitive
member 2 undergoes the~ act1on of brush leng-t.h-adjusting
member 560 As a resul-t, the e~cess of the developer (the
amount oi` the developer wllich corresponds to the amount
of the developer removed from the surface of photosensitive
member 2) is removed from developer-holding member 50~ and
let fal.l into receptac:le 58O
In the cleaning metllod using cleaning device 34-
described above, it is important to avoid the forma-tion
of a deposit of the developer in area 60 which is upstream ~-
of position Q at which the surface of photosensitive member
2 is closest to the surface of developer--holding member 50
in the moving direction of the surface of photosensitive
member 20 ~he deposit of the developer is formed by the
developer which has been carried to area 60 by developer-
.
holding member 50O If the deposit of the developer isformed ln area 60, the surface of photosensitive member 2
which has been mechanically brushed at position Q then
: maXes contact with the deposi-t of the developer not suf-
ficientl~y held to the surface of developer-holding member
50O As a result, the developer would again adhere to the
surface of photosensitive member 2~
To avoid the formation of the deposit of the
developer in area 60, it is irnportant to dispose magnet 52
- 37 - -~
..
., ,: . , ,,, , . :
-; , . ,., . . . . ~
. . ,
.~
~z~9~
so tha.t one of tae r,o]es of ~agnet 52 ;Illich is clOsê.--t
to position ~ is positioned doi~lrls-tream ol` the rota-tlng
lirection of the developer~ ()~LdinLr Illember 50 ~y cer-tain
angle y ~Jhich is prei`erably not ~.nore than 15 wit'
.respec-t to posi.tion ~O
It is also very important to properly acLjust
distance d4 between the surface o~ developer-holding
member 50 and the surface o~ photosensitive member 2 at
position Q where the two surfaces are the closest to each
other, and distance d5 between the end of brush length-
adjusting member 56 and the suxface of developer-holding
member 50O Distance d4 can be se-t within the range of
1D 2 to 0O5 mm~ and distance d5 within the range of Go6
to 0025 mm, in such a manner that the deposit of -the ~.
developer wi]l not formO
Cleaning can be pe-rformed fairly well even if :
the rotating direction of developer-holding member 50 is ~.
the same as the moving direction of photosensitive member
20 In this case, the relation between d4 and d5 is quite ;
the same as that between d2 and dl described hereinaboveO
Decreasing of the amount of the developer
to be removed
It is known that in -the conventional electro-
static copying apparatus for performing the electrostatic
copying process described hereinabove with reference to
Figure 5, the amount of -the developer to be removed from
. the surface of photosensitive member 2 by cleaning device
34 and received by receptacle 58 is fairly largeO The
reason for this has been investigatedO It has been
- 38 -
- \
consequertly round that tr~e _moun-t OL` soner particles
which remain on the surfacf. Or pho-tosensitiJe men.ber 2
after the trallst`~r is r-lativeL-y small and can ~)e
neglectecl if` the toner image transierring step is carried
out l.^;ith a good transfer efficiency; and that the amount
of toner particles wllich r~e carried to the cleaning
de `JiCe as adhering to the surface of photo;ensitive member
2 is cor.siderably large, and a con~;iderable portion of the
developer particles removed fron! the surf`ace of photosensi~
-tive member 2 into receptacle 58 by c]eaning device 34
is the la-tter-mentioned -tonerO
In the conventional electrosta-tic copying appa-
ratus, corona discharge device 2~) for charging and the
original illuminating lamp (not shown) of optical system
22 are adapted to be de-energized as ~oon as an electro-
static latent image is formed on -the s~rface of photo-
sensitive member 2 by the charging step and image-exposing
stepO Hence, a part of -the surface of photosensitive
member 2 which is positioned between the shield side plates
of corona discharge device 20 upon the comple-tion of the
electrostatic latent image-ornling step is already charged~
and~ without being exposed to the light from the lamp of
optica] system 22, proceeds -to a position where it under-
goes the action of developing device 6 by the rotation
of photosensitive member 20 Hence, a fairly large amount
of the developer adheres to -that part of the surface of
photosensitive member 2 which has been described above -~
(the developer adheres to cover the entire surface black)O
~he above-mentloned par-t of the surface of photosensitive
- 39 -
~z~
member 2 does not form an image corresponding to an
original image. Usually, without being contacted closely
with the receptor sheet at transfer station 24, this part
advances past transferring station 24, the position where
it undergoes the action of electrostatic eliminating
lamp 32 to a position where it undergoes the action of
c].eaning device 34. Accordingly, a considerably large
amount of the developer adhering to the above-mentioned
part of the surface of photosensitive member 2 by the
action of developer device 6 is carried directly to a
position where it undergoes the action of cleaning device
34. This developer is removed from the surface of photo-
sensitive member 2 by the action of cleaning device 34,
and constitutes a major proportion of the developer
received in receptacle 58.
The conventional electrostatic copying apparatus,
therefore, has the disadvantage that a considerable amount
of the developer unwanted by developing device 6 is wasted,
and the irradiating light from electrostatic eliminating
l.amp 32 is shielded by the developer adhering the surface j .
of photosensitive member 2 in the state of solid black
and the eliminating effect by electrostatic elimina.ting
lamp 32 is insufficient.
This disadvantage can be overcome to a consider-
able extent by de-energizing only the corona discharge
device 20 upon the completion of the electrostatic latent
image-forming step, and de-energizing the original-
projecting lamp of optical system 22 with a predetermined
time lag (substantially equal to, or longer than, the ~ime
- 40 -
. ~
_ .. ; ,
9~
required until that part of photosensitive member 2,
which is situated between the shield side plates of
discharge device 20 when corona discharge device 20 is
de-energized, passes the original image projecting zone
by the rotation of photosensitive member 2). By so doing,
that part of photosensitive member 2, which has been
charged when corona discharge device 20 is de-energized,
receives light from the original-illuminating lamp which
is reflected by the white back surface of an original
press member (not shown), the original, etc. in the original
image projecting zone, and thereby a considerable amount
o the electrostatic charge applied to the above-mentioned
part of photosensitive member 2 is removed.
As stated above, the light from the original-
illuminating lamp is projected on the surface of photo-
sensitive member 2 afterit has been reflected by~the -
back surface of the original press member or by the original.
Especially when the light is refIected by an original
including an image area, the static charge applied to the
above-mentioned part of photosensitive member 2 cannot be
completely eliminated. To eliminate the electrostatic
charge exactly and completely, an additional static
eliminating lamp (now shown) capable of lighting the - -
surface of photosensitive member 2 directly or through a
reflecting mirror is provided betw0en corona discharge
device 20 and developing device 6, and for a time period
which corresponds to the above-mentioned time lag, this
additional eliminating lamp is energized upon the com- --
pletion of the electrostatic latent image-forming step
- 41 -
.. - ~ , ; .~ :
. .
.:
(that is, when corona discharge device 20 and original-
illuminating lamp of optical system 22 have been de- -
energized). The above-mentioned problem can therefore
be completely solved by this contrivance. If the toner
image transferring step is carried out with a good trans-
ferring efficiency ~for example, at least 85%, especially
at least 90%) in the apparatus of this construction, the
amount of the developer which remains on the surface of
photosensitive member 2 after transfer of the toner image
is very small, and therefore, cleaning device 3~ can be
omitted.
Electrostatic copying apparatus
The following description concerns a preferred
embodiment of the electrostatic copying apparatus in
accordance with this invention for carrying out the
electrostatic copying process described above with ref-
erence to Figure 5 which comprises applying an electro-
static charge to the surface of photosensitive member 2
having a photoconductive layer by corona discharge device
20 (the charging step), then projecting the image of an
original on the surface of photosensitive member 2 by an
optical system (the original image exposing step), thus
forming an electrostatic latent image corresponding to the
original image on the surface of photosensitive member 2,
then applying a fine powdery developer (toner) to
the electrostatic latent image on the surface of photo-
sensitive member 2 by developing device 6 to develop the
latent image into a toner image (the electrostatic latent
image developing step), trans-ferring the resulting toner
- ~2 -
.
~%~
image to the surface of a receptor sheet (the toner image
transferring step), and fixing the toner image on the
receptor sheet (the fixing step).
General_construction
The general construction of the electrostatic
copying apparatus is described with reference to Figures
8 and 9.
The electrostatic copying apparatus has a sub-
stantially rectangular parallelpipedal housing shown
generally at 100. On the top surface of housing 100 are
provided transparent plate 102 on which to place an original
to be copied, flexible, original-holding plate 104 for
covering the original placed on transparent plate 102,
and control panel 106 having control swi~ches and other
components to be described.
Rotary drum 108 having photosensitive member 2
mounted on its surface is disposed at the center of the
lower half portion of housing 100. Around drum 108 to
be rotated in the direction of arrow B are arranged along
the moving direction of the surface of rotary drum 108 a :
corona discharge device 20 for charging, developing device ~ -
6, corona discharge device 36 for transfer, electrostatic
eliminating lamp 32, and cleaning device 34 in this- order.
Optical system 22 for projecting the image of an original
placed on transparent plate 102 onto the surface of rotary
drum 108 in an exposing station between corona discharge
device 20 for charging and developing device 6 is disposed
above rotary drum 108 and within the upper half portion
of housing 100. Below the rotary drum and within the lower
- 43 -
fl
'. -
;
part of housing 100 is provided conveyor system 112 for
conveying a receptor sheet from paper-supplying cassette
llOa or llOb mounted on one side portion of housing 100
(on the right-hand side in Figures 8 and 9) to receiving
tray 30 mounted on the other side portion ~on the left-
hand side in Figures 8 and 9) of housing 100 through a
transfer station having corona discharge device 36 dis-
posed in it. Fixing device 28 composed of a pair of
cooperating press rollers 114 a and 114b is provided in
a space in receptor sheet conveying system 112 which is
between the transfer station and receiving tray 30.
The constituent elements of the apparatus are - -
described in more detail below.
Partitioning of the housing, and a cooling system
Within housing 100 are disposed front vertical
base plate 101 extending from its one side to the other
: side and rear vertical base plate 103 (see Figure 11).
Between two base plates 101 and 103 is fixed partitioning
plate 116 which extends from one side of housing 100 to
the other and partitions the space between two base plates 101
and 103 into an upper portion including op~ical system
22 and a lower portion including rotary drum 108, the
various devices provided around rotary drum 108 and
receptor sheet conveyor system 112. As will be described
hereinbelow, partitioning plate 116 has opening 118 through
which to pass the light to be projected on the surface of
rotary drum 108 by the optical system 23. At a position
on partitioning plate 116 which is apart from opening
118 to the left in Figure 9 by a fixed distance, the lower
- 44 -
~ ,,.
,
'
~%~
end of vertical transparent plate 120 through which the
above light can pass is connected. Preferably, vertical
transparent plate 120 is formed in the same thickness
and of the same material as transparent plate 102. If
vertical transparent plate 120 does not have the same
refractive index as transparent plate 102> the image
projected on the surface of rotary drum 108 would be out
of focus. The upper end of vertical transparent plate
120 is connected to a partitioning plate extending to the
right side portion of housing 100. Partitioning plate
122 has opening 124 at its right-hand side portion extend-
ing substantially horizontally. FurthermoreJ partitioning
plate 126 for blocking the communication of opening 118
in partitioning plate 116 with opening 124 in partitioning
plate 122 is removably secured between partitioning plates
116 and 122.
It will be appreciated therefore that the space
between front vertical base plate 101 and rear vertical
base plate 103 is partitioned into an upper half and a
lower half by partitioning plate 116, and the upper half `
and lower half portions are each sealed by the cooperation
of partitioning plates 116, 122 and 126 and vertical
transparent plate 120 so that they do not communicate with
each other.
The upper half portion of the space between
front vertical base plate 101 and rear vertical base plate
103 includes optical system 22, and suction blower 130
which constitutes a cooling system for cooling original-
illuminating lamp 128 of optical system 22. As will be
- 45 -
'~ '''!
,, ~
described hereinbelow, this lamp 128 is adapted to be
reciprocated substantially horizontally within housing
100. Suction blower 130 provided near the left end of
the upper half portion sucks the air through suction
opening 132 formed on the left side wall of housing 100,
as shown by arrows. The air flow sucked by suction blower
130 is let out from opening 136 formed in partitioning
plate 134, then proceeds toward the right of the upper
half portion, passes through opening 124 of partitioning
plate 122, further passes through discharge opening 138
formed on the right-hand side wall of housing 100, and
is thus discharged from housing 100. This air flow effec-
tively cools original-illuminating lamp 128.
Generally, original-illuminating lamp 128 of
optical system 22 attains a considerably high temperature
in operation. It is necessary therefore to suck the air from
outside the housing 100, direct the air flow to original-
illuminating lamp 128 to cool it, and then discharge the
air flow out of housing 100. On the other hand, photo-
sensitive member 2 having a photoconductive layer mounted
on the surface of rotary drum 108 is sensitive to heat.
If, therefore, the air flow which has attained a high
temperature as a result of cooling original-illuminating
lamp 128 contacts the surface of rotary drum 108, photo
sensitive me-mber 2 is likely to be deteriorated. Further
more, if the air flow for cooling original-illuminating
lamp 128 acts on developing device 6 and cleaning device
34 provided around rotary drum 108, the fine powdery
developer will be scattered by the action of the cooling
- 46 -
~L~2~
air flow. It is likely therefore that the apparatus will
be soiled or the resulting toner image will be distorted.
In the preferred embodiment of the electrostatic
copying apparatus of this invention described hereinabove,
the upper half portion of housing 100 in which optical
system 22 and suction blower 130 are provided is non-
communicatively partitioned by the cooperation of parti-
tioning plates 116, 122 and 126 and vertical transparent
plate 120 from the lower half portion of housing 100 in
which rotary drum 108 and developing device 6 and other
components around rotary drum 108 are provided. Accordingly, -
the air flow which is sucked by suction blower 130 through
suction opening 132 and discharged from discharge opening
138 to cool original-illuminating lamp 128 does not flow
into the lower half portion. Consequently, there is no - -
likelihood of the deterioration of photosensitive member 2
by the hot air flow, or of the soiling of~the apparatus ;
and the distortion of the toner image by the scattering
of the toner particles. -
In the preferred embodiment of the electrostatic
copying apparatus of this invention, partitioning plate
122 is provided which has a portion extending from the
upper edge of discharge opening 138 formed on the right-
hand side wall of housing 100 substantially horizontally -
to the inside of housing 100 by a fixed distance. Rarti-
tioning plate 122 has opening 124 for the air flow.
Accordingly, the air flow for cooling is well discharged
through opening 124 and discharge opening 138, but the
light from illuminating lamp 128 is mostly shielded by
- 47 -
.
..
the part of partitioning plate 122 and the right-hand
wall of housing 100 which are at right angles to each
other. Hence, the light from lamp 128 does not leak
from housing 100, and therefore, is not likely to affect
the eyes of the operator. To prevent light leakage from
lamp 128 completely, a plurality of shielding plates
~not shown) inclined at a fixed angle may be provided
at intervals at opening 124 and/or discharge opening 138.
Partitioning plates 116, 122, etc. also have
an effect of reinforcing housing 100 and increasing its
rigidity.
In the embodiment shown in the drawings, vertical
transparent plate 120 is provided at a position spaced
to the left from opening 118 of partitioning plate 116 by
a fixed distance. Alternatively, transparent plate 120
may be provided directly at opening 118 of partitioning
plate 116. In this case, the upper half portion of housing
100 including optical system 22 and suction blower 130 is
non-communicatively separated from the lower half portion
including rotary drum 108 and developing device 6 and
other component parts around the drum only by means of
partitioning plate 116 and transparent plate 120 provided
at opening 118. If desired, therefore, auxiliary parti-
tioning plate 122 can be omitted. If, however, the pro-
vision of auxiliary partitioning plate 122 is omitted,
a considerable amount of the light from lamp 128 of optical
system 22 leaks from housing 100 through discharge opening
138. Furthermore~ it is likely that the light from out-
side housing 100 will fall upon in-mirror lens 144 to
- 48 -
l"`, .
~.~o~
cause optical noises to optical system 22. Accordingly,
when auxiliary partitioning plate 122 is to be omitted,
it is desirable to provide a plurality of light shielding
plates inclined at a fixed angle at intervals in dis-
charge opening 138.
Instead of providing transparent plate 120 at
opening 118 of partitioning plate 116, one or a plurality
of air jet nozzles may be provided near opening 118 so
that the upper portion of housing 100 is non-communicatively
separated from its lower portion at opening 118 by the
ackion of an air flow which 1Ows somewhat upwardly into
opening 118 from the tips of the air jet nozzles (by the
so-called air curtain action). The pressure of the air
flow from the air nozzle needs to be equal to, or somewhat
higher than, the pressure of the cooling air stream which
would flow from the upper portion to the lower portion of
housing 100 through opening 118 in the absence of such
air flow from the air nozzles. When such an air nozzle
is provided and transparent plate 120 having the same -~
refractive index as transparent plate 102 on which to
place an original is absent in the light path extending
from in-mirror lens 144 of optical system 22 (optical
system 22 will be described in detail hereinbelow) to
the surface of rotary drum 108, this light path must be
adjusted to include the light path that would be increased
by the refractive index of transparent plate 102. If
further desired, instead of providing an air curtain as
described above, the flowing of the air stream from the
upper portion to the lower portion of the housing can be
_ ~9 _
,
~L~2~
blocked by providing a suitable sucking means in the lower
portion of housing 100 to maintain the air pressure in
the lower portion somewhat higher than the air pressure
of the upper portion of the housing.
Optical system
Now, referring to Figures 9 to ll, the optical
system is described in detail.
Optical system 22 includes original-illuminating
lamp 128, first refIecting mirror 140, second reflecting
mirror 142, ln-mirror lens 144, and third reflecting
mirror 146. Illuminating lamp 128 and first reflecting
mirror 140 are secured to first support frame 150 slidably
mounted on a pair of suspending rods 148a and 148b which
extend substantially horizontally in the upper half portion
of the space between front vertical base plate 101 and
rear vertical base plate 103. Second reflecting mirror
142 is secured to second support frame 152 mounted slidably
on suspending rods 148a and 148b. In-mirror lens 144 is
secured at a fixed position between partitioning plates
116 and 134. Third reflecting mirror 146 is secured to
a predetermined position between partitioning plates 116
and 122.
First support frame 150 to which lamp 128 and
first reflecting mirror 140 are secured is reciprocable
between the position shown by the solid line in Figure 9
and the position shown by the two-dot chain line in
Figure 9, and second support frame 152 to which second
reflecting mirror 142 is secured is reciprocable at a
speed half of the speed of first support frame 150 between
- 50 -
~z~9~
the position shown by the solid line and the position
shown by two-dot chain line shown in Figure 9.
By particular reference to Figure 10, a drive
mechanism for driving first support frame 150 and second
support frame 152 in this manner will be described. In
rear vertical base plate 103 (see Figure 11) provided in
housing 100, pulley 156 to be driven by a motor via a ~-
drive system to be described, and first follow-up pulley
158 and second follow-up pulley 160 are rotatably provided.
Third follow-up pulley 162 is rotatably provided in second
support frame 152. First wire 164 and second wire 166
are wrapped around these pulleys in the following manner.
First wire 164 which is fixed to rear vertical base plate
103 and extends from one end 164a is first wrapped about
first follow-up pulley 158, then about pulley 156 and
further about second follow-up pulley 160, and other end
164b ls fixed to first su M ort frame 150. Second wire
166 fixed to rear vertical base plate 103 and extending -
from one end 166a is wrapped about third follow-up pulley
162, and other end 166b is fixed to first support frame 150.
Thus, when pulley 156 is rotated in the direction
of arrow E at a fixed speed, first support frame 150 is
moved in the direction of arrow E at the peripheral speed
of pulley 156. Second support frame 152 is moved in the
direction of arrow E at a speed one hàlf of the above
peripheral speed by the principle of tackle. When pulley
156 is rotated in the direction of arrow F at a fixed
speed, first support frame 150 is moved in the direction
of arrow A at the same peripheral speed as pulley 156,
.,~ j
~2~,g~
and second support frame 152 is mov~(l in the direction
of arro~l F at a s~eed ~al~` Of t~le }?erip~lera.l speed of
pulley l56 in accordance l~ith -t,he pI~in~i-ple oî tacl~{leO
Op~ical sys~-lm 2' suc(,fessively scans the i~age
of the original placecl on transparen-t ~late 102 and pro-
jects it onto the surface of drum ]08 while .f:irst support
frame 150 moves from the position shown by th.e solid line
to the position shown by the two-dot chain line at the
same mo~ing speed. as the moving speed of the periphery
of rotary drum 108 and second support frame 152 noves
from the position shown by the solid line to the position
shown by the two-dot chain li ne at a speed half of tile
moving speed of the periphery of ,rotary d.rum 1080 :First
support frame 150 and second support frane 152 rnay be
constructed such that in case of need, they can be returned
at faster speeds tharl their moving speeds mentioned above
from the position shown by the two-dot chain line -to the
position shown by the solid lineO - :
~he path of' the reflecting light of the original
illuminated by l.amp 128 secured to first support frame
150 is briefly describedO The reflecting light from the
original first passes through transparent plate 102 and
reaches first reflecting mirror 1400 It is reflected by
first reflecting mirror 140, and reaches second reflecting
mirror 142 where it is further reflectedu ~he reflected
light is then reflected on-to the mirror within in-mirror
lens 144, passe~ through vertical transparent pla-te 1209
and reaches third reflecting mirror 1460 It is reflected
by third reflecting mirror 146, and reaches the surface
- 52 --
" , . .
:.
~3 2~90
of rotary drum 1080 When thc original is scanned by
lamp 12~, first reflecting nirror 140 and second reflect-
ing rnirror 142 while first support frame 150 and secord
su~port ~rame 152 move, lamp 12& and first ref]ecting
mirror 140 move at the same s,peed as the peripheral ~peed
of rotary drum 108, whereas second reflecting mirror 142
moves at a speed half of this spGedO Accordingly~ -through-
out the entire step of scanning the origiral, the optical
length from the original to in-mirror lens 144, and the
optical length from in-mirror lens 144 to the surface of
rotary drum 108 are always main-tained substan-tially
constantO If vertical transparent plate 120 is made in
the same thic'~ness and of the same material as transparent
plate 102 on ~Ihich to place the original, the influence
(io eD ~ the refractive index) of transparent plate 102 on
the light path extending from the original to the lens
of in-mirror lens 144 becomes equal to the influence -~
(io e~, the refractive index) of vertical transparent
plate 120 on the light path e~tending from the lens of
ln-mirror lens 144 to the surface of rotary drum 1080
Accordingly, the individual elements of optical system
22 can be positioned without consideration of -the effects
of transparent plate 102 and vertical transparert plate
120 on the light paths
In optical system 22 in which first reflecting
mirror 14~ and second reflecting rnirror 142 move a-t
different speeds along a pair of suspending rods 148a ~ `
and 148b, the distance be-tween the reflecting mirrors
changes according to the position of first support frame 150
53 -
Q~ -
to which first r.eflecting mirror 140 is fi-~d ancl seeor~!d
support frame L52 to llhich s~l:ond r_flectir~ mirror 142
is seeureclO ~ccordirl~ly~ at the ti~ rixinG both encls
o:f.` eaeh o.E :Eirst wire 164 an(l ~:;econd wire :l66 at fixed
positions or a-t l;~e -time of ~.~xchanging the uciecl ~Jires 16
ancl 1661 it is eonsiclerably (:li.i`fiel1]-t -to posi~ion first
support frame 150 and second supporl frame 152 ir. a fi.~ed
relation on suspending rods 14~a and 148b so tnat -the
optieal length from the original to in-mirror lens 144
O i5 equal to the optieal length from in-mirror lens 144
to the s~faee of rotary drum 108~
However, aceording to the optieal sy.stem 22 in
the preferred embodiment of the eleetrostatie copying
apparatus of this invention, first support frame 150 and
seeond support frame 152 mounted slidably on suspending
rods 148a and 148b ean be positioned in a fixed relation
very easily and rapidly, and the two ends of first wire
164 and/or seeond wire 166 ean be fi.xed at predetermined
positionsu
In optieal system 22 in aeeordance with the
preferred emboliment of the electrostatie eopying appa-
ratus of this invention, a part of first support frame
150, for example block portion 150a having a hole through
whieh rod 148b extends, ancl a part of seeond support
frame 152, for example block portion 152a having a hole
through whieh rod 148b extends~ are formed in a predetermined
dimension~ ~hese block portions 150a and 152a eooperate
with a suitable stopping member~ for e~ample support
braeket 168 (see Figures 8 and 11) seeured to the right-hand
_ 5~ _
, ,
"~
end portion of r~ar vertical base~ plate 103 alld support-
ing the rigllt-hand end portion of suspencLing rod 14~b,
thereby to form a positioni~lg meclns for .irst support
frame 150 and seconcl support framQ l520 '~peci.fically,
optical system 22 sho~rn in the drawings i9 constructed
such that first suppor-t frame 150 and second support
frame 152 can be suitably positioned in a fixed re].ation
by contacting the ri.gh1;-hand end of block portion 152a
of second support frame 152 with the left--hand end of
support bracket 168 and contacting the right-hand end
of block portion 150a of first support frame 150 with
the left end of block portion 152a o~ second support
frame 1520 Accordi.ngly, in assembIing the apparatus,
block portion 150a of first support frame 150, block
portion 152a of second support frame 152 and support
bracket 168 are contacted wi-th each other as described :~
hereinabove, and both ends of first wire 164 and/or second
~.,
wire 166 are fixed to predc-termined positions of rear - -
vertical base plate 103 and first ~support frame 1500 Thus,
~20 ~ first support frame ~50 and second support~frame 152 are
held so that they can move~ ln a fixed relation to each
other~ Then, first support frame 150 and second support
frame 152 can be moved to the starting positibn of scannin~
shown,for example,by the solid line~ ln Figu~e 9O
According to the preferred embodiment of the
electrostatic copying apparatus in acoordance with this
invention, optical system 22 is constructed such tha-t `
the positioning of in-mirror lens 144, namely focus
adjustment, can be perYormed nore easily than in
~l~2~Q~
conventional optical systemsO
~ccording -to the prior techniques, the posi-
tioning of in-mirror lenr, 144 i., performed by ~irst
observing an image projected on the s~irface of rotary
dr~un 10~ to determine whether the image of the ori~sinal
placed on transparent plate 102 has been formed correctly
on the surface of rotary clrum 108, and then meticulously
adjusting the position of in-mirror lens 144 according
- to the result of observationO It is reiativ-ely difficult
however to observe the surface of rotary drum 108 while -~
meticulously adausting the posltion of in-mirror lens 144,
because rotary drum 108 is disposed substantially centrally
in housing 100 and the various devices provided around the
drum willblock vision beyond the ~.,urface of rotary drum ~:.
1080
In optical system 22 in accordance with the
preferred embodiment of the electrostatic copying appa- :~
ratus of this inverltion~ a semi-transparent image-focusing
plate (member 170 shown by the two-dot chain line in -- ~:
Figure 9) made, for example, of ground glass can be tem-
porarily fixed at a position spaced from the surface of
third reflecting rirror by a length same as the optical
length extending from the surface of third reflecting
mirror 146 to rotary drum 1080
In -this optical system 22, in-mirror lens l
: can be positioned relatively easily by temporarily fixing
image focusing plate 170 before the right-hand side wall
of housing 100, partitioning plate 126 and third reflect- : -:
ing mirror 146 are mountedO By so doing, the image of
- 56 -
,,' ~ ` ', , -, : - '
~L~,Z~
the original placed on trailsparent plate 102 is projected
onto image focusing plate 1700 Since i~lage-focusing
plate 170 is positioned near t~le rigll-t-hand side wall
of housing 100 (the wall is not ~ounted when posltioning
in-mirror lens 144) and is macle of a serni-transparent
material such as ground glass~ the image of the ori~inal
projected on the focal plane of image focusing plate 170
can be observed easily from outside the right-hand side ~ -
wall of housing 100 (in Figure 9)O Accordi~gly, the
posi-tion of in-mirror lens 144 can be easily adjusted
me-ticulously while observing the irr.age of the original ~ -
projected onto the focal plane of image focusing plate 1700
Irnage focusing plate 170 ls mounted at such a positlon
that the optical length from the surface of third reflecting
1~ mirror 146 to be provided later to the focal plane of image
focusing plate 170 is equal to the length from the surface
of third reflecting mirror 146 to that portion of rotary drum
108 onto whieh the image of the original will be projectedO
Hence, if in-mirror lens 144 is flxed correctly at a posi-
tion at which the image of the original is correctly
formed on the focal plane of 1mage focusing plate 170,
and third reflecting mirror 146 will be later mounted, the
image of the orig]nal can be correctly formed on the
surface of rotar~ drum 108
After in-mirror lens 144 has been positioned
and fixed, ima6e focusing plate 170 is removed, and then
third reflecting mirror 146, partitioning plate 126 and
the right-hand side wall of housing 1~0 are mountedO
~he space between partitioning plates 126 and 116 in which
- 57 -
",
.`` ~,~,~Q~O
image focusing plate 170 is temporarily fixed is utilized
as a space for accommodating electrical means for
operating and controlling various component parts of the
electrostatic copying apparatus. --
Rotary drum and ~rarious devices provided around it
Referring to Figures 8, 9 and 12 to 14, rotary
drum 108 and corona discharge device 20, developing device
6, corona discharge device 36, static eliminating lamp
32 and c].eaning device 34 disposed around rotary drum 108
are described below in detail.
In a preferred embodiment of the electrostatlc
copying apparatus of this invention, a support generally
shown at 172 is secured to front vertical base plate 101
and rear vertical base plate 103 centrally beneath parti-
tioning plate 116 in a manner such that it is freely
slidable in the forward and rearward directions (the
direction perpendicular to the sheet surface of Figure 9).
To support 172 are secured rotary drum 108, corona dis-
charge device 20 for charging, developing device 6 and : ~
cleaning device 34. ..
.
Referrlng to Figures 12 and 13, support 172includes vertical front plate 174 and vertical rear plate
176 arranged substant1ally parallel to each:other with
a distance therebetween correspondlng:nearly to the dis- ;
tance between front vertical base plate 101 and rear ;~
vertical base plate 103, and a pair of horizontal members
178 and 180 which extend from both side portions of vertical .~ ;
front plate 174 substantially horizontally over vertical
rear plate 176. Preferably, support 172 further includes
~ ~, ...
- : : .... . . . .
. ... . .
! ,, i, ~ .
~.lZ0~9~
cover 131 which is removably secured and covers the left
portion o.f the top of support 1720 Guide rolls 182 and 184
are mounted on the rear ends of hori~ontal members 178
and 180 respectively which extend beyond vertical rear
plate 176. Guide rail 188 having groove 186 at its
bottom surface is secured to horizontal mernber 178~ Flat
guide rail 190 is secured to horizontal member 1800
Furthermore, notch 192 is provided at the upper edge of
: horizontal member 178 near ltS forward endO
Front vertical base plate 101 has opening 195 -~-
having a shape corresponding to the shape of support 172
: so that support 172 can be set at a predetermined operat-
ing position through opening 1950 A pair of channel-like
guide rails 194 and 196 (see ~igures 14, 13 and 9) are
: 15 fixed to front vertical base plate 101 and rear vertical ~:.
base plate 1030 Guide rails 194 and 196 which extend
rearward from front vertical basè plate 101 over rear : .
vertical base plate.103 receive and guide the guide rolls
lB2 and 184 mounted on the rear ends of horizontal members ~
~: 20 178 and 180 of support 1720 Guide roll 198 adapted to .`~: -
:
~ . be engaged with groove 186 of guide rail 188 and guide ~:-
. ~
~: roll 200 adapted to be engaged with the:bottom surface of
~ guide rail 190 are rotatably mounted respe~tivel~ on the
`~: front vertical base plate 101 near the forward ends of
guide rails 194 and 1960 At the upper portion of guide
rail 194 near its forward end i9 provided locking means
202 (see Figures 11 and 13) which cooperates with notch
192 of horizontal member 178~ Loc~ing means 202 secured
to partitioning plate 116 may be of any known type, and ~ ~
- 59 - .
, . . ~ , . .. ..
includes an engaging me~ber (not sllown) l,jhich is elasti-
cally restrained by an elastic means such as a spring,
extends do~mward throu~h the openings :Eormed in parti-
tioning plate 116 and guide rail 194, and comes into
engagelnent with notch 192, and operating part 20~ which
by hand opera-ting, can lift the engaging memberO
It will be appreciated therefore that support
172 is moun~ed so that it is slidable in the forward and
rearward directions (the direction perpendicular to the :-
sheet surface of Figure 9) through opening 195 formed in
front vertical base plate lOlo Briefly stated, support
172 is mounted slidably by engaging guide rolls 182 and
184 with guide rails 194 and 196 and guide rails 188 and
190 with guide rolls 198 and 2000 When support 172 is
inserted rearward and reaches the operating position (i~eO,
t'ne position at which vertical front plate 174 is situated
substantially on the same plane as front ver-tical base
plate lOl,and vertical rear plate 176 is situated adjacent
rear vertical base plate 103)~ loc~ing means 202 and notch . :
192 cooperate to loc~ support 172 releasablyO ~o pull ~ :
out the support forward and if desired, remove it from
housing 100, operating part 204 of locking means 202 lS :
operated to release the cooperation of locking means 202
and notch 192, and support 172 is caused to slide forward~ :
Rotar~J drum 108, corona discharge device 20,
developing device 6 and cleaning device 34 are mounted
on support 172 described aboveO
Referring to Figures 12 to 1~, ~he mounting of ~`
rotary drum 108 on support 172 will be describedO In each
- 60 -
" ' ~ ' ' '' ,,.:, '......... .. .
r - \
~z~
of vertical front plate 174 and vertical rear plate 1~6
of support 172 is forrned a slot 208 e~tending upward from
the lower edge of each of plates 17~ aad 176 to its
central part in a somewhat incllned mannerO Slot 208
is adapted to receive shaft support member 218 rotatably
fitted in each end por-tion of shaft 206 of rotary drum
108 through a suitable means SUCll as ball bearingsO
~haft 210 is rotatably secured to vertical front plate
174 and vertical rear plate 176 of support 172, and rotary
drum-holding lever 212 for supporting shaft support member --
218 in place is secured to each of the forward end of ~ -
shaft 210 which projects forward beyond vertical front -~
plate 174 and the rear end of shaft 210 which projects
rearward beyond vertical rear plate 176u
Rotary drum 108 can be mounted on, and removed -
from, support 1'72 in the following mannerO To mount :
rotary drum 108 on support 172, holding lever 212 i.s -~;
turned clockwise by a suitable angle from the position - ~-
shown in Figure 13 to position it at a~point which does
not interfere with slot 2080 ~hen, rotary drum 108 is `
: fitted into support 172 from below9 and shaft suppcrting ~ :
: members 218~fitted in the end portions of shaft 206 are
inserted into slots 208O Holding levers 212 are then
turned to the positions shown in Figure 13, and flxed in
: 25 position b~ such a means as screws 2130 As a result,
shaft supporting member 218 fitted in both end portions
of shaft 206 of rotary drum l08 is supported in a sub- :
stantially circular hole defined by the hook-like forward .:
end of holding lever 212 and the semi-clrcular upper end
- 61 -
, . . . . .
,.
:
l~Z~90
of slot 2080 'rO remc>ve rotary drum 108 frorr. support 172,
the fixing of holding levers 212 by means such as screws
213 is released, and holding levers 212 are tnrned clock-
wise fronl the positions silown in ~igure 1 3o ~he rotary
drum 108 is moved downward along slots 2080 ~o the rear-
most end of shaft 206 of rotary drum 108 is fixed joint
217 which is adapted to be drivingly connected to joint
216 rotatably mounted on rear vertical base plate 103
~joint 216 is rotated by a motor through a drive system
to be described below in detail)O Joints 216 and 217 may
be of any kno~,rn type, and are adapted to be connected to
each other when their angular positions are in agreement
as prescribedO ~o the forward end portion of shaft 206 is
fixed a grip knob 220 which the operator can grip when
pulling out or removing support 172 from housing 100 or
when mounting or removing rotary drum 1080 Grip knob 220
(see ~igure 8 also) is connected to shaft 206 via a known
one-way clutch placed therein, and can rotate rotary drum
108 and its shaft 206 only when tu~ned in a predetermined
rotating direction of the ro-tary drum 108 (l.e., the direc-
tion shown by arrow B --- see Figure 9)O ~ince joints 216
and 217 are connected to each other when their angular
positions are in agreement~as prescribed, Join-ts 216 and
217 must be brought into agreement by rotating rotary drum
108 and shaft 206 when mounting rotary drum 108
As will be described in detail below, developing
device 6 and developer-holding member 50 oI cleaning device
34 are adapted to be rotated when rotary drum 108 is rotatedO
If, therefore, rotary drum 108 is adapted to be rotated
-- 62 --
. . .
.. ..
,
f ~
also in a direction opposite to the prescribed rotating
direction (the direction shown by arrow B), developing
device 6 and developer-holding members 8 and 50 of
cleaning device 34 are rotated in a direction opposite
to the predetermined rotating direction, and it is li1~ely
therefore that the developer contained in developer
supplier 14 of developing device 6 will abnormally over-
flow from it, or build up on the surface of the rotary
: drum~ However, since in rotary drum 108 shown in the
drawings, securing of grip knob 220 to the forward end
of shaft 206 is through the one-l~ay clutch, even when by
inadvertence in InoUnting rotary drum 108, grip knob 220
is rotated in a direction opposite to the predetermined
direction, rotary drum 103 rotates only in the predetermined
direction, and developing device 6 and cleaning device 34 ---
are free from such adverse effects as described aboveO -~
,~
Corona discharge device 20 for charging is
mounted detachably on support 172 by fitting it into
: opening 222 formed in vertical fron-t plate 1740 Mounting
and detaching of corona disch~rge device 20 can be very
: easily performed by gripplng grip knob 224 provided at its
; front endO Member 225 which constitutes a shield case for
~ corona discharge device 20 is fixed at a position between
: vertical front plate 174 and vertical rear plate 176 where
corona discharge device 20 is to be provided~ ; ;
Developing device 6 which ls preferably of the
type described in detail with reference to ~igure 2 is
also mounted on support 1720 Developer supplier 14 in
developing device 6 is fi~ed in place by a suitable means
.
- .
~2~)90
.
such as positioning pin 226 to be inserted into the
~ront plate and the rear plate of supplier 14 through
vertical front plate 174 and vertical rear plate 176
of support 1720 Further~ore, as described in detail
with reference to Fig~ e 2, developer-hol(ling member 8
in the form of a hollow cylindrical sleeve having a
roll-like permanent magnet disposed in it is pivotably
supported by bearing member 227 provided at each of the
: front and rear plates of developer supplier 140 Pin 229
fixed to bearing member 227 is received in adjusting
piece 228 adjustably mounted on vertical front plate 174 .-
and vertical rear plate 176 of support 1720 ~hus, the :
distance between the surface of rotary drum 108 and the
surface of developer-holding member 8 can be meticulously
adjustedO ~he entire developing device 6 consisting of
developer-holding member 8 and developer supplier 14 as
an integral unit can be detached from support 172 by :
merely detaching the pin 229 fitted in the bearing member ~ -:.
::
227 and the positioning pin 2260 A developer supply . -
opening positioned at the top of developer supplier 14
is situated at the left end of the top surface of support :
172, and therefore, is open without~being covered by cover
181 (Figure 12)o A brush length-adjusting member pre-
-
ferably of the type described hereinabove with reference .: -
- ~ 25 to Figure 2 is secured to developer supplier 140
Support 172 further has cleaning device 34,
preferably of the structure described in detail herein-
~.. -- . . ~
above with reference to Figure 7, mounted on ito ~he
shaft for developer-holding .nember 50 of cleaning device
- 64 -
.
:' ~' . . . . .
~ - ~
~z~9o
34 is rotatably supported by the ad~,nstin~ piece 230, and
adjusting piece 230 is ad,justably Inounted ~n v~rtical
from plate 17~ ancl vertical rear plate l760 Hence~ by
adjustlng the position of adjus-tin~.r, piece 230, tlle
clearance between the surface of rotary drum 1()8 and the
surface of developer-holding member 50 can be meticulousl-g
adjustedO ~urthermore; developer-holding member 50 can
be detached from support 172 by merely detaching adjusting
piece 230 from vertical front plate 174 and vertical rear -- -
plate 1760 Developer receiver 58 of cleaning device 34
is fixed in position betweerl vertical front plate 174 andi :
and its forward end portion is placed on frame member 54
which, together with the lower edge of vertical front plate
174, defines a receiving opening of developer-receiver 580
A brush length-adjusting member of the type described in detail ;
hereinabove with reference to ~igure 7 (not shown in Figure ~.
13) is secured to frame member 54O Receptacle 58 which ~ -
is inserted through the receivi.ng opening defined at its ~.
front portion and placed on frame member 54 can be easily
mounted or de-tached by grasping grip knob 232 provided
at its fron-t endO - ~:
Electrostatic eliminating lamp 32 and corona ~ -
discharge device 36 for transfer are mounted directly on
front vertical base plate 101 and rear vertical base plate
103 at predetermined positions around rotary drum 1080 ~ .
As most clearly shown in Figure 14~ electrostatic eliminat-
ing lamp 32 is fixed to front vertical base plate 101 and
rear vertical base plate 103 by a suitable means such as
screws at a predetermined position with respect to the
- h5 -
.
~, , ' - ' ' ` , . ~ ,
OQ~
surface of rotary drum 108 to be mounted on support 172.
Corona discharge device 36 for transfer is mounted
detachably at a predetermined position with respect to
the surface of rotary drum 108 to be mounted on support
172 by being fitted into notch 234 of a prescribed shape
formed in front vertical base plate 101 and rear vertical
base plate 103. Corona discharge device 36 can be very
easily mounted and detached by grasping grip knob 236
provided at its front end.
As best shown in Figure 14, nail 40 for peeling
a receptor,sheet is fixed to rear vertical base plate 103
via vixing bracket 238 at a position which is adjacent
corona discharge device 36 downstream of the moving direc- -
tion of the surface of rotary drum 108 and is near the rear
end of corona discharge device 36 for transfer. Nail 40
serves to peel a receptor sheet from the surface of rotary
drum 108 having a toner image~so as to send the receptor
sheet having the toner image to fixing device 28 through
a passage defined 'oy receptor sheet conveying roller 240
and receptor sheet guide plate 42. The receptor sheet
,
peeled off from rotary drum 108 by the action of peeling
nail 40 undergoes the action of peel roller 241 (see
Figure 19) which cooperates with oonveying roller 240 and
fed onto guide plate 42. To peel the firmly adhering
receptor sheet from the surface of rotary drum 108 exactly,
it is preferred to make peeling nail 40 such that its
forward end 40a is engaged with the edge of the receptor
sheet projecting from the surface of rotary drum 108.
This can be achieved by maklng the rear end of rotary drum
- 66 -
..... .
~.z~9~
108 smaller in diameter than the remainder (the surface
of the smaller-diameter portion is not utilized for the
formation of an electrostatic latent image and a toner
image), or by somewhat decreasing the width of rotary
drum 108.
In the electrostatic copying apparatus of the
type described hereinabove for performing the electrostatic
copying process described above by reference to Figure 5,
the developer contained in developer supplier 14 is con- ~ ~-
sumed as the copying process is performed. Hence, the
developer must be supplied occasionally to supplier 14.
Furthermore, as the copying process proceeds, the developer
removed from the surface of rotary drum 108 builds up in -~
receptacle 58 of cleaning device 34. Hence, the developer
in receptacle 58 must be occasionally recovered. On the
other hand, as described in detail hereinabove with ref-
erence to Figure 2, in order to perform the developing
step in good condition, it is important to.maintain dis-
tance d2 between the surface of developer-holding member 8
and the surface of rotary drum 108 and distance dl between `~
the developer holding member 8 and the forward end of
brush length-adjusting member 16 secured to developer
supplier 14 at suitable values. Furthermore, as already
describèd with reference to Figure 7, to perform ~he
cleaning step in good condition, it is important to main- `~
tain distance d4 between the surface of developer-holding
member 50 and the surface of rotary drum 108, and distance
d5 between the surface of developer-holding member 50 and ~-
the forward end of brush length-adjusting member 56 at
- 67 -
~2~9~
suitable values.
In the preferred embodiment of the electrostatic
copying apparatus of this invention described above,
developing device 6 together with rotary drum 108 is
mounted on support 172 which is mounted on front vertical
base plate 101 and rear vertical base plate 103 in a manner
such that it is slidable in the forward and rearward dir-
ections, and the supply opening of developer supplier 14
of developing device 6 is opened upward. Hence, supplying
of the developer to developer supplier 14 can be performed
by merely pulling support 172 forward and feeding the ;
developer through the supply opening. Thus, it is not ~ ;
necessary to construct the apparatus such that for supplying
the developer, the entire developing device 6 is caused
to slide forward with respect to rotary drum 108, or
developer supplier 14 to slide forward with respect to -~
developer-holding member 8 of developing device 6. If
the apparatus is constructed in this way as in conventional
electrostatic copying apparatus, it is extremely difficult,
if not impossible, to maintain distance d exactly at a
~ 2 ~ f
predetermined value, and distance d2 is likely to be
changed by the sliding of the entire developing device 6 or
developer supplier 14 in the forward and r0arward direc-
tions.
In the preferred embodiment of the electrostatic
copying apparatus in accordance with this invention, clean-
ing device 34 is also mounted on support 172, and only
the receptacle 58 of cleaning 34 is adapted to be moved
forward of support 172 and pulled out. Hence, the developer
:
- 68 -
.
Z , - ~ : , . . :
~ `~
that builds up in receptacle 58 can be rapidly and easily
recovered without any adverse effect on distance d4 by
merely pulling out receptacle 58 forward. There is no
need to construct the apparatus such that in recovering
the developer, the entire cleaning device 34 may slide
forward with respect to rotary drum 108, or frame member
54 having brush length-adjusting member 56 fitted thereto
may slide forward with respect to developer-holding member
50 of cleaning device 34. Accordingly, distance d4 can
be maintained exactly at a predetermined value.
Furthermore, in the preferred embodiment of
the electrostatic copying apparatus of this invention, as
can be easily understood from Figures 9 and 14, when ~
support 172 is pulled out by forward sliding, a transfer ;
station having corona discharge device 36 and a receptor ~ -
sheet passage nearby (the receptor sheet conveying system
and the~ receptor sheet passage in their entirety will be
described hereinbelow) are directly exposed. Thus, any :.
receptor sheet which jams up at these portions can be
easily removed.
Since corona discharge device 20 is mounted
easily detachably on support 172 and corona discharge
device 36, on front vertical base plate 101 and rear
vertical base plate 103, they can be very easily repaired,
cleaned or replaced in the event they are damaged, cut
off or soiled. Support 172 having developing device 6,
cleaning device 34 and corona discharge device 20 mounted
on it, when pulled out forward to:~a predetermined position,
is blocked by a suitable blocking member to check further
- 69 -
,, ~
o
forward movement and thus to prevent inadvertent dropping
of support 172. It is also possible ~o construct the
apparatus such that support 172 can be completely detached
from housing 100 by somewhat lifting it after it has
been pulled out forward to a predetermined position.
Support 172 completely detached from housing lO0 in this
way can be placed temporarily on an auxiliary frame (not
shown) which can hold support 172 by engagement with
bottom surfaces of guide rails 188 and 190.
Figure 13A shows a modified example of a support
which is mounted on front vertical base plate 101 and
rear vertical base plate 103 so that it is slidable in
the forward and rearward directions (i.e., the direction
perpendicular to the surface of the sheet surface of
Figure 9) and a rotary drum, a developing device and a
cleaning device which are mounted on the support. ~ , The support shown generally at 472 in the
modified example shown in Figure 13A includes vertical
front plate 474 and vertical rear plate 476 which are
disposed substantially parallel to each other with an
interval therebetween corresponding to the distance
between front vertical base plate 101 and rear vertical
base plate 103, and a pair of channel-like horizontal
members 478 and 480 which extend substantially horizontally ~
from both side portions of vertical front plate 474 beyond -
vertical rear plate 476. Horizontal members 478 and 480 -
of support 472 are slidably engaged respectively with a
pair of guide rails 494 and 496 which are slidably received
in a pair of guide rails 493 (only one of ~hem is shown
- 70 -
~.
,",~1
: .. : ., ,
..
-- ~20~0
in the drawing) extending backward from front vertical
base plate 101 (not shown in Figure 13A) beyond rear
vertical base plate 103. This ca~lses support 472 to be
mounted on front vertical base plate 101 and rear vertical
base plate 103 so that it is slidable in the forward and
rearward directions. Locking means 502 of any known type
is provided in the inside upper edge portion of vertical
front plate 474 of support 472. Locking means 502 is ~ -
elastically and releasably engaged with part 195a of
opening 195 of front vertical base plate 101 when support
member 472 is inserted and reaches an operating position
where vertical front plate 474 is situated substantially
on the same plane as front vertical base plate 101 and
vertical rear plate 476 is adjacent rear vertical base
plate 103.
Rotary drum 108, corona discharge device 20 for
charging, developing device 706 and cleaning device 734
are mounted on support 472.
Rotary drum 108 shown in Figure 13A is con~
structed such that cylindrical body 409 having a photo- -
sensitive material on its surface can be easily detached
; as required. Speclfically, rotary drum 108 shown in
Figure 13A has support shaft 406 and a pair of discs 410 and
412 rotatably mounted on support shaft 406 through bearing
means 407. Discs 410 and 412 are connected to each other
by a plurality (three in the drawing) of stays 414 arranged
in spaced apart relationship in the circumferential direc-
tion. To disc 412 is fixed gear 344 which is to mesh with
gear 354 of developing device 706 and gear 348 of cleaning
- 71 -
~r
.
~zoo9o ~:
device 734, as will be described in detail hereinbelow
by reference to Figure 19. Cylindrical body 409 having
photosensitive member 2 is fitted with discs 410 and
412 and stays 414, inserted in an annular recess formed
in the inside part of the end of cylinder 409, and held
in position by disc 416 fixed to disc 410 by a plurality
of screws 415.
In the modified example shown in Figure 13A in
which support shaft 406 is supported on bearing means 407,
it is not necessary to maintain the linearity of the axis
of shaft 406a severely over its entire length. In other ~-
words, the shaft is easy to make since it is sufficient
to finish only that part of shaft 406 at which to locate
bearing means 407 within the range of predetermined linearity.
Rotary drum 108 of the above construction is
,
detachably mounted on support 472 by detachably fixing
support shaft 406 to vertical front plate 474 and vertical
rear plate 476 of support 472. In each of vertical front ~ -
plate 474 and vertical rear plate 476, slot 408 extending ~ -
upwardly from the lower edge of each plate to its center
: . ,
in a somewhat inclined manner is~ formed. Each slot 408
has part 408a having a width smaller than the diameter -
of support shaft 406 by a predetermined~dimension and --~
-
circular part 408b having its center somewhat deviated
with respect to the longitudinal axial line of this part
408a and having subs~antlally the same dlameter as the
diameter of support shaft 406. Chord-like groove 405
having a width corresponding to each of vertical front
plate 474 and vertical rear plate 476 is formed at both
.
~ -
- 72 -
~2~9~)
end portions of support shaft 406. Notch 404 is formed
at the forward end portion of support shaft 406 to indicate
the position of groove 405. To mount rotary drum 108 on
support 472, support shaft 406 is maintained in the con-
dition shown in Figure 13A in which its grooves 405
receive vertical front plate 474 and vertical rear plate
476 of support 472 respectively, and inserted into slot
408 up to the part 408b via part 408a. Then, support
shaft 406 is turned counterclockwise in Figure 13A to
direct grooves 405 at both its ends downward. In the
next place, stopper 413 having projecting portion 413a to
be engaged with groove 405 is fixed only to vertical front
plate 474 by means of screws 417 to block the rotation of
support shaft 406, thereby to mo~mt support shaft 406 and -
rotary drum 108 exactly at predetermined positions of
support 472. Rotary drum 108 can be detached from support
472 by reversing the above procedure. When rotary drum
108 has been mounted at a predetermined position of support
472 and support 472 is inserted at a predetermined position
~i.e.~ the position at which vertical front plate 474 is
situated on substantially the same plane as front vertical
base plate 101 and vertical rear plate 476 is adjacent
rear vertical base plate 103), gear 344 of rotary drum 108
is drivingly connected to a drive system to be described.
The driving connection of gear 344 to the drive system can
be achieved, for example, by pivotably supporting a shaft
(not shown) to be rotated by the drive system on rear
vertical base plate 103, and fixing a gear (not shown)
to be in mesh with gear 344 at the forward end portion
3L~Z~9~
of this s'la~t which extends be-~orld ~ertical rear plate : :
4760
In rotary dIwn 108 ,.hown in l~igure 13A, the
cylindrical body 409 has a~ its both ends par-ts 409a
and 409b having no photose.lsi~ive member 2~ and small-
diameter part 409c a~jacent part 4-0~aO ~he small-dia~neter
part 409c is positioned corresponding to peeling nail 440
fixed to the inside suxface of vertical ~ront plate 474
Peeling nail 44~ has the sa~.e flmction as peeling nail 440
~10 already described hereinabove, and acts -to peel off a
~ firmly adhering transfer sheet from the surface of ro-tary
: drurn 1080 In the embodiment shown in ~igure 13A7 peeling :-
nail 440 is fixed to the inside surface of vertical fron-t
plate 474O Accordingly~ a peeling roller (not shown in
Figure 13A) which acts cooperatively with peellng nail
440 is mounted not on rear vertical base plate 10~ but
: on front vertical base plate lOlo
Corona discharge device 20 for charging~ same
~ as in the ernbodiment clescribed hereinabove with reference
:~ 20 to ~:gures 12 and 13, is detachably mounted on support
472 by inserting it into the opening formed in vertical ~ -
~; front plate 474O
Developing device 706 shol~n in Figure 13A includes
developer supplier 714, developer-holding member 708 in
the form of a hollow cylindrical sleeve fixed to the front
and rear plates of developer supplier 7145 and a roll-like
permanent magnet (llOt shown) rotatably mounted by a suit-
able bearing within developer-holding membex 7080 In
developing device 706 shown in ~igure 13A, unlike developing
- 74 -
.... . . .
.,, , , , . , :
~, . , , ,- . , . -, - .
: - , . : .
`~
. ~
llZ~0913
device 6 shown in Figure 2, developer-holding member
708 remains stationary, and the permanent magnet inside
it rotates. The developer fed from developer supplier
714 onto the surface of developer-holding member 708 is
moved over the surface of developer-holding member 708
by the rotation of the roll-like permanent magnet. The
roll-like permanent magnet is rotated by the driving
force transmitted by gear 354 fixed to a shaft (not shown)
for the roll-like permanent magnet which extends through
support shaft 707 integrated with developer-holding
member 708.
- 75 -
, , ,
~lZO~
Developing device 706 of the ~bove construction is
detachably mlounted on support 472 by inserting auxiliary
holding pins 715 fixed to the fron-t and rear plates of
developer su.pplier 714 into slots ~4~ formed in vertical
front plate 474 and vertical rear p].a-te 476 of support 472,
insertlng both end portions of support shaft 707 for developer-
holdin~ member 708 into slots 446 formed in ver-tical front
plate 474 and vertical rear pl.ate -~7~, turning the stopper 44~ :
(made preferably of an elastic material) from the position ~ - -
shown by the solid line to the position shown by the one-dot
: : chain line, putting it on a pin and fi.xing it there to hold .
support shaft 707 in slots 446~ .Accordingly, both developer
supplier 714 and developer-holding member 708 can be removably
mounted on support 472 very easilyO The dlstance between the
15 surface of rotary drum 108 and the surface of developer-
holding mamber 708 is prescribed as desired by contacting a
pair of rings 711 rotatably mounted on both end portions of
: support skaft 707 via bearing 709 and having a diameter
~ J.
larger than tke diameter of developer-holding member 708 -~
;~ 20 by a predetermined dlmension, with p~arts 409a and 409b at botk ~.
ends of rotary drum 108.
Cleaning device 734 illustrated in ~igure 13A
; ~ includes support frame 754, developer-kolding member 750
in the form of a hollow cylindrical sleeve fixed to support
frame 750~ roll-like permanent magnet 749 rotatably mounted
within developer-holding member 750 by a suitable bearing
means (not shown), and develcper receiver 7580 In cleaning
device 734 of this structure, substan-tially same as in
developing device 706, developer-holding member 750 remains
- 76 -
::
. . ..
, , : ,,, . ,- : :' . ':
r-\
~2~19~
stationary, and magnet 749 is rotated by the driving force
transmitted by gear 348 fixed to a shaft (not shown) for
magnet 749 which extends through the inside of support shaft
751 integrated with developer-holding member 750.
Cleaning device 734 of the construction described
above is detachably mounted on support 472 in the following
manner. Auxiliary holding pins 755 fixed to the two ends
of support frame 754 are inserted into slots 482 formed in
vertical front plate 474 and vertical rear plate 476. A
portion of support shaft 751 which is near its each end is
inserted into slot 484 formed in each of vertical front plate
474 and vertical rear plate 476, and each of stoppers 486
preferably made of an elastic material is turned from the
position shown by the solid line to the position shown by
the one-dot chain line, put on a pin and fixed there to hold
support shaft 751 within slots 484. As a result, both support
frame 754 and developer-holding member 750 fixed to it are
detachably mounted on support 472 very easily. The distance ; -~
between the surface of rotary drum 108 and the surface of
developer-holding member 750 is set as prescribed by contacting
a pair of rings 752 rotatably mounted through bearings 753 ~ ~-
on the end portions of support shaft 751 and having a diameter ~ ~
, .
larger than the diameter of developer-holding member 750 by `
a predetermined dimension, with parts 409a and 409b at both -
end portions of rotary drum 108 at which no photosensitive
material 2 is present. Receptacle 758 is detachably mounted
on support frame 754 by bringing L-shaped flange 759 formed
at its one edge portion into engagement with stay 761 fixed
to support frame 754, and placing the bottom surface of
- 77 -
"I
~ - , ., , , : ,
~ ,
. .
., .
receptacle 758 on a sultable support member (not shown) which
projects from the inside surface of support frame 754. Hence,
as required, the entire cleaning device 734 can be removed
from support 472 with receptacle 758 remaining attached to
support frame 754. Or receptacle 758 alone can be very easily
detached from support 472 independently of support frame 754
and developer-holding member 750 fixed to it ~i.e., without
removing the entire cleaning device 734). This permits
very rapid and easy inspection and maintenance.
Obviously, developing device and the cleaning
device in the preferred embodiment of the electrostatic -
copying apparatus of this invention described above can be -
fîxed to, and detached from, the support very easily.
Receptor sheet conveying system
The receptor sheet conveying system 112 is described
with reference to Figures 9, 16~ 17A and 17B. -~
Receptor sheet conveying system 112 for conveying -~
a receptor shee~ consists of a cassette receiving section
for receiving a part~of paper cassettes llOa or llOb, and a
.-,
receptor sheet conveylng system for conveying a receptor
sheet stacked in cassette llOa or llOb ~o receiving tray 30
: -
through a transfer station~having corona discharge device 36
for transfer disposed in it and a fixing station having ;~
fixing device 28 disposed in it. ; -
.:
First, the cassette receiving section is described
with reference to Figures 16, 17A and 17B. Paper supplying
:
cassettes llOa and llOb differ from each other in ~heir own
,
sizes and in the sizes of receptor sheets stacked therein
(for example, cassette llOa contains receptor sheets with a
- 78 -
, , . . , ,~. :
2~9~
size of JIS-B5, and cassette llOb contains receptor sheets --
with a size of JIS-A4). Otherwise, their constructions are
substantially the same, and the cassette receiving section
for receiving a part of cassette 110a is substantially the
same as the receiving section for receiving a part of
cassette 110b. The following description, therefore, is
directed mainly to paper supplying cassette 110a and the
cassette receiving section for receiving it.
The paper supplying cassette 110a is composed of ~
substantially rectangular parallelpipedal case 242a with an
open top, and case 242a includes auxiliary bottom plate 244a -~
made of a relatively rigid material such as cardboard, metal -~
or synthetic resin and layer 246a of receptor sheets of a
predetermined size ~for example, B5). In Figure 16, bottom
plate 244a and receptor sheet layer 246a are omitted.
Fitting lever-receiving recess 248a is formed on both sides
of case 242a, and opening 250a for receiving receptor sheet-
lifting lever 286a is formed centrally near the forward
;~ end of the bottom plate of case 242a. Nails 252a for blocking
.-.
the forward end of receptor sheet are fixed to the top end
of each corner of case 242a at its forward end. Wedge-shaped~
notch 253a is formed in the upper edge of the~forward por~ion
of each side plate of ease 242a. The operations of fitting
lever-receiving recesses 248a, lifting lever-receiving opening
250a, blocking nails 252a and notches 253a will be described -~
in detail hereinbelow. ~`
Openings 254a and 254b are formed on the right-hand ~;
wall of housing 100 of the electrostatic copying apparatus
to receive paper supplying cassettes 110a and 110b (see
- 79 -
,j , . . , :" , , , . . : , :::::.
`:
: Fig~re 9)0 Inwardly of oper.ings 254a and 254b are provided
receiving member 256a and 256b (omitted in Figure 16) which
act on the front parts of the paper supplying cassettes ;~
llOa and llOb to be inserted through these openings 254a
and 254bo For convenience, one of the receiving members,
256a, is described~ Xeceiving member 256a has a cassette
bottom g~iding portion 258a which extends downwardly and
inclinedly from a position immediately inwardly of opening
254a toward the inside of housing 100 and guides the bottom
surface of paper supplying cassette llOa inserted through
: opening 254a~ cassette end abu-tting portion 260a which -the ~`:
forward end of paper supplying cassette llOa to be inserted
through opening 2~a a~uts, and receptor sheet guiding
portion 262a which further extends -toward the inside of
housing 100 from the top end of abutting portion 260a and
guides the receptor sheet fed from cassette llOa to the
receptor sheet conveying system, as will be described herein-
belowO
~t a position above cassette bottom guiding portion
258a by a predetermined distance from it, shaft 266a to be
rotated selectively in ~he direction of arrow E (in the
clockwise direction in ~igures 16, 17A and 17B) by the action
of clutch MC3 which may be an electromagnetic clutch or a
combination of a ro-tary spring clutch and an electromagnetic
solenoid is mounted rotatably on front vertical base plate
101 and rear vertical base plate 1030 ~ pair of paper feed
rollers 268, for example~ are secured to shaft 266aO ~ pair
of stop plates 270a with which wedge-shaped notches 253a formed
in the paper supplying cassette llOa come into engagement
_ 80 -
0(~9~3
are fixed to front vertical base plate 101 and rear vertical
base plate 103 at a position above cassette bottom guiding
porti.on 258a.
Immediately inwardly of receiving mer~ber 256a7
Shaft 272a is rotatably mounted on front vertical base plate
101 and r~ar vertical base plate 103~ A nearly fan-shaped
positioning member 274a is fixed to one end (the forward
end in ~igure 16) of shaft 272a. Mear shaft 272a is disposed a
stop pin 276a ~ixed to front vertical base plate 101O A pull
spring 278a is set bet~een stop pin 276a and that end of
positioning member 274a which is farther away from stop pin
276aO ~ pair of projecting sections 280a and 282a to be engaged
with stop pin 276a are formed at that end of positioning
member 27LLa which i5 nearer stop pin 276a, and that portion
of positioning member 27L~a which is between two projecting
sections 280a and 282a forms an arc having a predetermined
radius of curvatureO ~he stop pin 276a, positioning member
274a and pull spring 278a are cons-tructed such that they ~;
operate as follows:
In the state sho~n in ~igures 16 and 17A in which
one projecting section 280a of positioning member 27L~a come
into engagement with stop pin 276a, shaft 272a is urged in
the clockwise direction by the elastic action of pull spring
278a, and therefore, shaft 272a i9 set in position by the
engagement of projecting section 200a with stop pin 276a.
If, as described hereinbelow, shaft 272a is turned counter-
clockwise in ~igures 16 and 17~ in resistance to the elastic
action of pull spring 278a as a result of operating the paper
supplying cassette 110a, the pull_spring 27~a retracts f~om its
- 81 -
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. .. .:
~ : ~ ,..... .. . ..
.
~^
~L%OQ9~
most stretched state and urges shaft 272a counterclockwise.
Accordingly, shaft 272a is turned by the elastic action of
pull spring 278a to the state illustrated in Figure 17B in
which other projecting section 282a of positioning member
274a comes into engagement with stop pin 276a, and set in
position. In other words, stop pin 276a, positioning
member 274a and pull spring 278a are constructed so as to -~
urge shaft 272a elastically to a first angular position at which
the projecting section 280a comes into engagement with stop
pin 276a (the angular position shown in Figure 16 and 17A),
or to a second angular position at which the projecting section
282a comes into engagement with pin 276a (the angular position
shown in Figure 17B).
: : .
To shaft 272a described above are fixed a pair of
cassette linking levers 284a with a distance therebetween
corresponding substantially to the width af paper cassette
llOa. When cassette llOa is inserted by contacting its bottom
.
surface with cassette bottom guiding portlon 258a of receiving -
member 256 with shaft 272a being at the first angular position -
~ described above, cassette linking levers 284a are fitted into
recesses 248a of cassette llOa. Intermediate between cassette
. .
~ ; linking levers 284a, receptor sheet-lifting lever 286a is ~ ~ -
:.
~ rotatably mounted on shat 272a. Receptor sheet-lifting ~ -
.
lever 286a can extend through opening 250a formed centrally
near the forward end portion~of the bottom plate of cassette ;
llOa and a notch (not shown) formed in receiving member 256a
at a position corresponding to opening 250a, and can directly ~` -
act on auxiliary bottom piate 244a and receptor sheet layer
246a placed in cassette IIOa. When sh-ft 272a is at the
;-
:'
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.e ~.................................................................. .. .
. . , , , ., .. .. ~ .- ~. . . .
-
~L~%~1~9~
first angular position, lever 286a is held in the position
shown in Figures 16 and 17A at which the forward end of
lever 286a is retracted from opening 250a. When shaft 272a
is turned to the second angular position described above,
lever 286a is elastically urged counterclockwise in Figures
16, 17A and 17B (in a direction to lift auxiliary bottom
plate 244a and receptor sheet layer 246a in cassette llOa)
by an elastic means such as spring 288a with one end fitted
to shaft 272a and the other end to lifting lever 286a.
It is believed to be already clear from the above
description how the paper supplying cassette llOa is inserted
into the casset~e receiving section and how a receptor sheet ;
is fed from the receptor sheet layer in cassette llOa. The
mechanism is summarized belowJ however.
Toiinsert cassette llOa into the receiving section
through opening 254a formed on the right-hand wall of housing
100, it is first necessary to contact the bottom surface of
cassette llOa with bottom guiding portion 258a of receiving
member 256a and insert cassette llOa until its forward end
abuts abutting portion 260a of receiving member 256aJ thus
attaining the state shown in Figures 16 and 17A. At this
timeJ shaft 272a is located at the first angular position at
which one of projecting sections 280a of positioning member
274a is in engagement with stop pin 276a. ThusJ upon the
insertion of cassette llOa as described above~ cassette
linking levers 284a fixed to shaft 272a are fitted into --
recesses 248a formed on both sides of the forward end portion
of cassette llOa. The transfer sheet lifting lever 286a
mounted on shaft 272a is locked at a retracted position at
- 83 -
,,
, .. . .
., . . :~ .. , :
. , :- ' .. :
`~ ~
~Z0~9~)
which its forward end is substantially on the same plane as
cassette bottom guiding portion 258a of receiving member 256a.
Then, paper supplying cassette llOa is turned in
a direction in which its forward end inserted in the receiving
section moves upwardly. As a result, as shown in Figure 17B,
notches 253a of cassette llOa come into engagement with stop
plates 270a to stop the turning of paper supplying cassette
llOa by pull spring 278a and to prevent its rearward movement.
At the same time, with the turning of the paper supplying
cassette llOa, cassette linking levers 284a are turned counter-
clockwise, and shaft 272a is brought to the second position
at which other projecting portion sections 282a of positioning
member 274a is engaged with stop pin 276a. Thus, lifting
lever 286a is unlocked, and by the action of spring 288a, is
elastically urged counterclockwise, whereby its forward end
- projects from opening 250a of cassette llOa and elastically
lifts auxiliary bottom plate 244a and receptor sheet layer 246a
in the cassette llOa to urge the topmost receptor sheet
elastically against paper feed roller 268a. Two corners of
the forward end of the topmost receptor sheet lifted by
lever 286a from layer 246a come into engagement with blocking
nails 252a to check its upward movement. l~hen in such a
condition, paper feed rollers 268a are rotated in the -~
direction of arrow E, the topmost receptor sheet urged
elastically against it is delivered toward the transfer
station, moved along guide portion 262a of receiving member
256a, and fed into a receptor sheet conveying system to be
described.
When it is desired to take out paper supplying
- 8~ -
.....
` -
cassette llOa from the receiving section after all the receptor
sheets in cassette llOa have been consumed, cassette llOa in
the state shown in Figure 17B is turned in a direction in
which its forward portion moves downward to attain the state
shown in Figure 17A. Consequently, notches 253a of paper
supplying cassette llOa depart from stop plates 270a, and
paper supplying cassette llOa is in condition for rearward
movement. At the same time, with the turning of the paper
supplying cassette llOa, cassette linking levers 284a and
~0 shaft 272a are turned clockwise, and shaft 272a is returned
to the first position at which one of projecting sections
280a of positioning member 271a comes into engagement with
stop pin 276a. The foremost end of ~aper supplying cassette ~-
llOa moving downward causes receptor sheet-lifting lever 286a
to rotate clockwise and return to its retracted position
where it is locked in positi.on. Thereafter, paper supplying
cassette llOa is moved rearward, and taken out of the receiving
section.
In paper supplying cassette llOa shown in the
drawings, auxiliary bottom plate 244a is substantially of
the same size as the receptor sheet placed on it, and only
the forward end portions of auxiliary bottom plate 244a and
receptor sheet layer 246a are lifted by the action of receptor
sheet lifting lever 286a. Accordingly, the receptor sheet
layer 246a is inclined at a certain angle. In this case,
the angle of the topmost receptor sheet with respect to
blocking nails 252a changes somewhat according to a change
in the thickness of receptor sheet layer 246a. Hence, the
action of blocking nails 252a on the receptor sheet are
.
~;
; , ; :
g~ ~
somewhat changed, and this may sometimes hamper the action
of delivering only the topmost receptor sheet exactly. To
cope with this situation, it is possible to utilize auxiliary
bottom plate 244a which is located only baneath the front
half of receptor sheet layer 246a and to provide a suitable
guide means on the inner surface of each of the two side walls
of case 242a whereby auxiliary bottom plate 244a is lifted
substantially in parallel to the bottom plate of cassette
llOa or llOb by the action of lifting lever 286a. According
to this construction, the front half of the receptor sheet
layer can be lifted substantially in parallel to the bottom ~-
plate of cassette llOa or llOb, and the angle of the topmost
receptor sheet with respect to blocking nail 252a can be -
maintained substantially constant, and therefore, the action
of blocking nail 252a on the rec~ptor sheet can be maintained
in the most suitable condition.
,~
Now, receptor sheet convéying system 112 will be `
described in detail below with reference mainly to Figure 9.
Receptor sheet conveying system 112 for conveying a receptor
sheet from cassette llOa or llOb to~receiving tray 30 through
the transfer station and fixing device 28 consists, for example,
of roller pairs 290, 292, 294 and 296 each consisting of a
driven roller and an idle roller, a receptor sheet guide
plate between the rolls in each pair, and receptor sheet ;~
conveying roller 240 and guide plate 42 already described above
with reference to Figure 14. It is of course possible, as
described in detail with reference to Figure 5, to provlde
electrostatic eliminators 44 and 46 above guide plate 42
and/or above the inside end portion of receiving tray 30
- 86 -
.
;, . . . . , : - .
- , :, : , :
so as to facilitate the conveying of receptor sheet. It is
important to construct the receptor sheet conveying system
112 such that paper jamming which occurs at any part
of receptor sheet conveying system 112 can be rapidly and
easily corrected. For this purpose, upstream of conveying
system 112 for example, the rollers and guide plate defining
the underside of the conveying system are mounted on
supporting frame 300 pivotably fixed to pin 298 so that
should paper jamming occur at this part, support frame 300 will be
turned clockwise with pin end 298 as a center to cope with
the paper jamming rapidly and easily. Paper jamming which
occurs in or near the transfer station can be adjusted easily
and rapidly by sliding in the forward direction (the direction
perpendicular to the sheet surface in Figure 9) support 172
having rotary drum 108, developing device 6 and cleaning
device 34 mounted on it, as already described. At the most
upstream part and the most downstream part of conveying system ~ ~-
112, paper jamming can be adjusted rapidly and easily by
first removing the paper supplying cassette llOa or llOb or ~-
receiving tray 30 ~hrough the opening which has been set free
by the removing of cassette llOa or llOb or receiving tray 30.
Drivlng system
The driving system is now described mainly with
reference to Figures 18 and l9.
; Referring to Figure 18, ln the preferred embodiment ;
of the electrostatic copying apparatus of *his invention~
optical system 22, rotary drum 108, developing device 6,
cleaning device 34,~fixing device 28,` and receptor sheet
conveying system 112 are driven by main motor DM (see Figure 9). `
'
.. .. .. . . . ........... ..
''~ , ' ` :' ` '
,~ ,~ ,
~lZ~O!~
Main driving twin sprocket 304 is fixed to the output shaft
of main motor DM. Around one member of sprocket 304 are
wrapped first endless chain 306 and second endless chain 308.
First endless chain 306 starts at one member of sprocket 304,
extends through driving sprocket 312 for driving optical
system 22 for scanning ~which sprocket is connected selectively
to driven pulley 156 ~see Figure lO) of optical system 22 by
a scanning electromagnetic clutch MCl (see Figure 20)],
sprocket 316 for returning optical system 22 [which sprocket
is connected selectively to driven pulley 156 of optical
system 22 by return electromagnetic clutch MC2 (see Figure
20)], linking sprocket 318 equlpped with a linking gear,
sprocket 320 for driving rotary drum 108 (which sprocket is
: drivingly connected to shaft 206 of rotary drum 108 as already ~ ~.
described with reference to Figure 15, or drivingly connected -
to gear 344 of rotary drum 108 via a driven shaft and a gear
fixed to it as described above with reference to Figure 13A)
and idle sprocket 322, and returns to the one member of
sprocket 304. Second endless chain 308 starts at the other : :
member of sprocket 304, extends through sprocket 324 fixed
to one of the shafts of a pair of:press rollers for driving
fixing device 28, sprocket 326 fixed to one shaft of roller --
.,
pair 294 for conveying a receptor sheet, idle sprocket 328
and sprocket 330 fixed to one shaft of roller pair 296 for
driving receptor sheet conveying rollers, and returns to the
other member of sprocket 304. Sprocket 332 equipped with a
linking gear is drivingly connected to linking sprocket 318
over which first endless chain 306 is stretched, and third
endless chain 334 is wrapped around sprocket 332. Third
- 88 -
, . .
~; f
, .....
, ~
~2~-9~
endless chain 334 starts from sprocket 332, exten~s through
sprocket 336a selectively connected to shaft 266a of paper feed
roller 268a by electromagnetic clutch CM3 (see Figure 20),
sprocket 336b connected selectively to shaft 266b of paper feed
roller 268b by electromagnetic clutch MC4 (see Figure 20), idle
sprocket 338, sprocket 340 fixed to one shaft of roller pair
290 for driving the receptor sheet conveying rollers and sprocket
342 fixed to one shaft of roller pair 292 for driving the receptor
sheet conveying roller, and returns to sprocket 332.
As clearly shown in Figure 19, gear 344 (see Figure 15
,
also) is fixed to rotary drum 108. This gear 344 is drivingly
connected to gear~348 fixed to the shaft of developer-holding ` -
member 50 of cleaning device~34 via speed increase gear device
346, and also to gear 354 fixed to the shaft of developer-holding ~-~
member 8 of developing device 6 via speed increase gear device
350 and idle gear 352. A gear (not shown) is fixed to the shaft
of receptor sheet conveying roller 240 disposed immediately down-
strèam of the transfer station, and is drivingly connected to idle -~
sprocket 322 via~an~idle gear.
It wiIl b~e appreciated therefore that optical system
22, rotary drum 108, developing device 6, cleaning device 34 and
receptor paper sheet conveying system 112 are properly driven
by;main motor DM.
Contro~l System~
The control system is described with reference to
; Figures 8, 20 and 24. ~ ~
Referring to Figure 8, control panel 106 disposed on
the top surface of housing lOO has main switch SW, knob ~C for
adjusting the amount of exposuTe, alarm lamp Ll for signalling
paper jamming, lamp L4 for paper supply, print button PB, preset
::: : ::
,
- 89 -
., "~
_ ~ ~.,
: ^ " . :
: . ,,~ ~ , :' :
- ,, ,. . . . ; ,.. -,
! ~
~1%~09~J
counter PC for presetting the number of copies required, and
receptor sheet selecting switch S8.
Within housing 100 are disposed at the positions shown
in Figure 20 switch Sl for detecting the return of first support
frame 150 having first reflecting mirror 140 mounted thereon to
a predetermined position, switch S2 for detecting the movement of
first support frame 150 beyond a predetermined position, switches
S3 and S4 which cooperatively detect paper jamming, switch S2 :
for successively starting the supply of receptor sheet when many : -
copies are made, and switches S6 and S7 for detec~ing the presence --:
: or absence of a receptor sheet in cassettes llOa and llOb.
~; Housing 100 also includes various electrical elements
such as electromagnetic clutch MCl for connecting sprocket 312
to pulley 156 of optical system 22, electromagnetic clutch MC2 ` ~ -
for connecting sprocket 316 to pulley 156 of optical system 22, ~-
electromagnetic clutch MC2~for connecting sprocket 316 to pulley -
156 of optical system 22, electromagnetic clutch MC3 for con-
necting the sprocket 336a to the shaft of paper feed roller 268a, :
electromagnetic clutch MC4 for connecting sprocket 336a to the -,
, ~.
:~ 20 shaft of paper feed roller 268a, electromagnetic clutch MC4 .
: .
:: for connecting sprocket 336a to the shaft of paper feed roller
268a, high voltage transformer IIV-i for corona discharge devlce
20, high voltage transformer HV-2 for corona discharge device
36, fan motor RM for driving suction blower 130, main motor
; DM, original illuminating lamp 128 for illuminating an original,
and electrostatic eliminator lamp 32.
The electrical elements describ~ed hereinabove with
reference to Figures 8 and 20 are incorporated:into the~ .:
electric circult shown in figures 21~to:24.~ The details of
the electric circuit itself:are believed to be readily
- 90 -
X
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~, . . . .
r~
f~2~9~
understandable from Figures 21 to 24, and a description cf
them is omittedO
~he operation of the preferred embodiments of the
electro9tatic copying apparatus of this invention is described
below by main reference.to Figure 8 and Figures 20 to 24O
~ When it i5 desired to copy an original placed on
tranSparent plate 102, main switch SW is turned onO ~hen,
~s required, e~po.5ure ~djusting knob EC is operated to adiust
variable resistance VR (Figure 21) to set the amount of light
from lamp 128 at a suitable valueO Furthermore, as required, ~ . .
receptor sheet select switch S8 is actuated to select a suitable
size (for example, B5 or A~) of receptor sheet to be conveyed
through conveying system 112.
Referring to Figures 22 and 2~, the selection of
receptor sheet and the detection of receptor sheet are . ::
describedO When for example, select switch S8 (Figure 2~
is actuated so as to select a receptor sheet (for example,
; of B-5 size) in cassette l].Oa~ the pressing of print button -~
PB will bring electromagnetic clutch MC3 for connecting the
sprocket 3~6a to the shaft of paper feed roller 268a into
the operative state, as can be understood from Figure 22. ~ -.
~urthermore, switch S8_1 shown in F.igure 22 interlocks with ~ ;
switch S8 whereby indicating lamp L2 provided within the
switch S8 change-over operating member on control panel 106
is lighted to indicate the selection of receptor sheet in -:
cassette llOa~ Switch S6 for detecting the presenc~ or ;~
absence of receptor sheet within cassette llOa lights paper .
supply lamp L4 when no receptor sheet is present~ and
subsequent pressing of print button PB does not actuate
_ 91 -
.
. . ,, . ,. ,.. , ~, . , ,~
~20~9~
,-,
relay Rl and -thus does not start the copying process. ~ne ;.
same c.~n be s~id when select switch S8 is ac-tuated to select
a receptor sheet (for example, wi-th a ~-;ize 4-4) in cassette
110bo
Assuming th.?~t preset counter PC i9 set at 1 (in :~
which case the terminal of preset counter PC is off), the
control of the operation of each component part of the
electrostatic copying apparf.-~tus is summ~rized as follows:
(i) When ~`irst support fr~me 150 does not return ~ -
to a predetermined position before the start of the copying
process by pressing the print~button PB, s~witch Sl is not
pressed but is normally openO Hence, electromagnetic cIutch
~ MC2 is energized to return first support frame 150 to the
:~ predetermined position
(ii) When print button PB is pressed, rel~y R
: ~ ` is operated and~itS contacts R1_~1 and Rl_2 a
a voltage is applied to~the baSe of transistor '~r2 to actuate~
relay SSR2 and close its contact SSR2 1~ ~hus, main motor
DM and f.~n motor FM rotate~flnd electrostatlc eliminator lamp
;20 . 32 is lightedO Contact Rl 1 self-maintalns relay~R
Contact~Rl 2 aotuates~relay R2 and~relay~RRl to~l1ght the
original 1l:lumin~t1ng lamp~l28 and to energ1ze~electromagnetic ~ -
~clutch MC3 (or MC4),- thus starting paper sùpply~
: : : : (iii) When the::forward end of a receptor sheet
~:~fed~ from paper cassette 110a~(or 110b)~presses~swltch S3
disposed on receptor sheet conveying system~ll2,:reIay R3~;
actuated and its contacts~R3a 2 and~:R3~ 3 are closed.
hen contact R3~ 1 is open, relay R2~is Rlso open and
electromagnetic clutch MC3 (or MC4) is deenergized. When .
~,
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:., : . :
.
, . . .
.
~z~9o
contact R3~ 2 is closed, condenser Cl i. charged, and upon
completion of charging~ a voltage is applied to transistor
~rl to close rela~ R3b and timer '~1 'I~he time during which
transistor Trl is kept in operation by the charge generated
in condenser Cl is determined b~ the tlme constant of a CR
circuit of conden~er Cl and variable resistance VR2o
Contact R3~ 3 actuates high voltage transformer XV-l for
corona discharGe device 200 When relay R3b operates, its
contact ~3b 1 is op~ned, and R3b l releases the self-~-~int.~ining ~ :
of Rl. Furthermore~ when R~b 2 is closed, SSRl is closed to
actuate high volt~ge transformer HV-2 for corona discharge
device ~60 R3b 3 serves to perform changeover between
electromagnetic clutch MCl and electromagnetic clutch MC2,
~nd is connected to electrom~gnetic clutch MCl when it is~ .:
closedO
(iv) ~imer ~1 is an on-delay timer, and after a
lapse of a certain period of time that can be suitably
prescribed from the time of actuation of R3a, its contact
~l l is closed. When Tl 1 is closed, magnetic clutch MCl is
energized to move first support frame 150 and second support
fr~me 152 forward (scanning movement)~ -.-
Specifically~ after a certain period of time preset
by timer ~l from the time when the forward end of a receptor
sheet fed from cassette 110a or 110b pressed switch S2
disposed on receptor sheet conveying system 112, first support
frame 150 ~nd second support frarne 152 begin to move forward,
and therefore, optical system 22 begins to scan the original
pl~ced on transparent plate 102 and to project the image of
the original onto the surface of rotary drum lO~o Accordingly,
- 93 ~
9~
by properly ~Adjustin~ -th- tilu_ to be s~t by tiMer 1~ the
forward end of the image of the original projected onto
the surf,~Ace of rotary drum 108 C~l` be ~ccur~tely rer,istered
. with t'ne forward end of a rec ptor sheet fed from paper
5 supplying c~Assette 11O~A (or llOb)o
I~nis registra-tion c~n also be performed by a
Mechanic~l element provided adjust~bly on recep-tcr sheet
conveying systel~ 112 and ~Adapted to be operrlted by the
forward end of receptor sheet, One example of such a
mechanical element is shown in ~igure 250 In this embodiment 9
instead of timer ~1 and switch S3, detecting member 606
is provided which serves -to sense the forw~rd end of receptor
sheet p~ssing between npper ,~lide plate 602 and lower
guide plate 604 de:Eining receptor sheet conveying system
;, 15 112 between roller pair 290 ~nd roller pair 2920 ~liS
; detecting member 606 at a part ne.~r its one end is
rotatably supported by rear vertical base plate 103, and
': at a p.~rt near its other end, rotatably supported by bracket
~: 608~ 3racket 608 is mounted on upper guide plate 602 adjust~bly
in the receptor shee-t conveying direction 610 by ~ screw which
extends -through elong~ted slot 612 extending in the receptor
sheet conveying direction 610 and is screwed to upper guide
.~ plate 6020 One end 606~ of detecting member 606 project5
beyond rear vertical base pl~te 103 and contacts an actuator
for microswitch 6140 Other end 606b of detecting member 606
pasSes through opening 616 formed in upper guide plate 602,
extends to receptor sheet conveying system 112 between upper
: guide plate 602 and lower guide plate 604, and further
: projects past opening 618 formed in lower guide plate 604.
- 94 -
llZOOgo
Detecting member 606 is rot~ted clockwi;e in ~igur~ 25 when
the forward end of reccptor sheet that is conveyed througn
conveying system 112 comes into eng.qgement with other end
606b ~ and its one end 606~ actuates micro,switch 6140 When
microswitch Gl4 is oper.lted, electroma~;netic clutch MCl i9
energized to start the forward movement of first support
frame 150 and second s~pport frame 1520 Hence, optical
system 22 begins to sc,~n the original placed on tr~nsparent
: ~ plate 102 ~nd to project the im,~ge of the original onto the
surf~ce of rotary drum 108, The forward end of the image
projected onto the surface of rotary drum 108 and the forward - .:
end of the receptor sheet can be properly registered by . :
changing the fixing position of br.~cket 60$ to move detecting
member 606 in the direction of .~rrow 620 with ~ part of detecting
member 606 which is near the rear vertical base plate 103 being
used as ~ fulcrum, and thus properly adjusting the sensing
position of other end 606b of detecting member 606O Preferably,
: a plurality of protruding po'rtions 622 are provided in the
widthwise directlon at spaced intervals on the top surf~ce
~:: 20 : of bottom guide plate 604- so as to bring the forward end of
receptor sheet into exact engagement with other end 606b of ' '-
: ~ d~etecting member 606 and to;f.~cilitate smooth conveying of
:; the receptor sheetD : ~ :
(v) When the re~r end of the~receptor sheet moving
on the receptor sheet conveying system 112 passes ~3~ the
pressing of ~3 is rele~sed -to set R3a off, ~nd ltS cont,~ct
R3a 1 is closed and con-tacts R3~ 2 and R3~ 3 ~re opened.
When R3~ 3 is off, the oper~tion of high voltage transformer
HV-l for corona disch.~rge device 20 is stopped. On the other
~'
- 95 - ~ :`
~2~Qg~
hand, condenser Cl is still charged after R3a 2 is opened.
Thus, until the charge in condenser Cl dissipates, transistor
T 1 operates to keep R3b in operation.
~vi) When the charge in condenser Cl is discharged
to a predetermined voltage level, R3b is opened, and its
contact R3b-2 is opened, When R3b 2 is off, SSRl and RRl
are opened to stop the operation of high voltage transformer
HV-2 for corona discharge device 36 and light the lamp 128. .
Furthermore, the connection of R3b 3 is switched from the
MCl side to the MC2 side to move first support frame 150
and second support frame 152 backward (return movement).
~vii) When first support frame 150 moves back-
ward and presses switch Sl provided at its stopping position,
switch Sl is turned off. Accordingly, electromagnetic clutch
MC2 is reset to stop first support frame 150 and second -~
- .
support frame 152.
(viii) When the rear end of the receptor sheet
moving on conveying system 112 departs switch S4 ~Figure 24),
switch S4 is turned off and KR2-R of keep relay KR2 actuates
~ to close KR2-1 and ground the collector of translstor Tr3. `-~
Thus, the application of a voltage from line X i5 stopped and
transistor Tr3 becomes inoperative. Tr2, however, is st~
in the operative state because of the charge on condenser
C2. When the charge is eliminated from condenser C2 to a
predetermined voltage level, Tr2 becomes inoperative. As a
result, relay SSR2 maintained in the closed state by contacts
Rl 1 and R3b 2 and transistor Tr3 is opened to stop main
` motor DM and fan motor FM and turn o-ff eliminator lamp 32.
The time during which Tr2 is maintained operative by the
- 96 -
~;!
, . . . - .,
Q~
charge on condenser C2 is determined by the time constant o~
a CR circuit of condenser C2 and variable resistance VR3.
VR3 is adjusted so that Tr2 becomes inoperative when the
receptor sheet after the leaving of its rear end from switch
S4 has been completely discharged onto the receiving tray.
When first support frame 150 and second support
frame 152 keep moving forward even after R3b is off, switch
S2 for sensing the overrunning of first support frame 150 ~ -
is pressed by first support frame 150 and actuates KR3-L -
of keep relay KR3 thereby to stop the copying process.
When preset counter PC is set at more than one ;-
number of copiesl its terminal is turned on and so maintained
until the remaining number becomes one. When the remaining -
number is one, the terminal is turned off. When preset
counter PC is on, the first support frame 150 presses switch S5
during its backward movement ~return movement) to turn on
switch S5 and thereby actuate relay R2. Consequently, its
contact R2 1 is closed to energize electromagnetic clutch
MC3 (or MC4) and to start paper supply. When the forward
end of receptor sheet supplled from cassette llOa or llOb ~ `
presses switch S3, relay R3a is actuated and its contact ~ ~ -
R3a l is opened. ~Furthermore, relay R2 ls opened to deenèrgize
the electromagnetic clutch MC3 (or MC4). Also,~R3a 2 and
R3 3 are closed. When R3a 2~is on, charge is 8enerated on
condenser Cl and transistor Trl is actuated. R3b is also
closed and~ its contact R3b 2 is closed. Thus, relay RRl is
` actuated to light original-illuminating lamp 128.
.
Sensing of paper jamming at receptor sheet conveying
system 112 is described with particular reference to Figure 24. -
- 97 -
~!
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~z~19~
The basic theory of sensing paper jamming is that
the time tc from the sensing of the rear end of receptor
sheet by switch S3 to the sensing of the rear end of the
same receptor sheet by switch S4 and the time tt preset by
on-delay timer T2 are set in a relation tc<tt, and the
operation of the apparatus is stopped and alarm lamp Ll
is lighted when paper jamming causes the relation tc>tt.
When the forward end of the receptor sheet presses switch
S3, relay 3a actuates to close its contact R3a 4. As a
result, transistor Tr5 becomes operative, and condenser C
is charged. However, KR2-L does not operate since the high
voltage side of KR2-L is simultaneously off. When the rear
end of the receptor sheet has passed swltch S3, the pressing
of S3 is released to open R3a 4 and set the high voltage
side in operation. Since transistor Tr5 is operative for
a certain period of time because of the charge on condenser
C3, KR2-L operates and its contact KR2-1 is closed thereby
to actuate timer T2 (when there is an input into timer T2,
its contact T2 1 is closed after a preset time, and when the :
input lS cut off before the preset ti~e elapses, timer T2
returns to the original state). When receptor sheet is
conveyed in normal condition, switch S4 senses the rear end
of the receptor sheet before the expiration of the time
:,
preset by timer T2 to actuate KR2-R. Accordingly, contact
KR2 1 is opened to stop the operation of timer T2. When
KR2-R does not ac~uate, contact T2 1 of tlmer T2 is closed
after the preset time to actuate KR2-L and open lts contact
KR3 1 Accordingly, the actuation of relay SSR2 stops and
the operation of the apparatus stops. At the same time,
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l~Z~Og~
alarm lamp Ll is lighted. The keep relays KR2 and KR3 operate
by one pulse and self-maintain mechanically, and even when
the power supply is cut off, the self-maintaining condition
remains. The self-maintaining condition may be released by
applying a signal to another input terminal (reset coil).
In resuming the operation of the apparatus after proper
correction of paper jamming, it is necessary to operate
reset switch RS which is provided for releasing the self-
maintaining condition of the relays.
99 _
L '~'1
