Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
A PROCESS UNIT AND
AN IMAGE FORMING APPARATUS USING THE SAME
BACKGROUND OF THE I~VENTION
Field of the Invention
The presen~ invention relates to a process
unit which contains, an image bearing member and all
or a part of process means actable on the imaqe bearing
member, and which is detachably mountable to a main
body of an apparatus, and also to an image forming
apparatus using such a process unit.
Description of the Prior Art
The prior art will be described with respect
to an electrophoto~raphic copying apparatus, as an
~5 example of the image forming apparatus.
Conventionally, electrophotographic machines
require a trained and expert serviceman for replacement
of a photosensitive member which is an image bearing
member, supply of the developer, disposal of the used
developer, cleaning of charging wires, replenishment
and adjustment of various parts and so on. It is needed
that the serviceman yoes to oEfices having the electro-
photo~raphic machines, whenever the servicing is
necessary. This is disadvantageous both for machine
makers and machine users, since the makers have to
establish and maintain the servicing network to meet
the demand, and the users have to wait for the
serviceman to arrive ~efore the restart of the machlne
operation.
- To remove those disadvantages, it ls recently
proposed, as disclosed in U.S. Patent Specification No.
3985436, that various process means, such as a photo-
sensitive member, a developing device, a cleaning means
and a charger are all contained in a casing as a unit,
and that the unit is replaced with a fresh unit when
the unit set in the machine is no longer usable, so that
all the means contained therein are exchanged simulta-
neously, thus saving the machine servicing operation.
This makes lt possible for users ~o replace various
elements without resort to an expert serviceman and
eliminates the necessity of periodical maintenance work.
Also, the serviceman's job can be tremendously reduced.
Additionally, the process unit can contain a developer
of a different color, which allows for the users to
take a copy with the different color. Another process
unit can replace to use the type of developing means
which suits the oriainal to be copied. Those are
additional advantages.
However, thiæ type of process unit involves
a problem that, when the unlt is replaced, or when the
unit is kept out of the image formlng apparatus, the
photosensitive member contained ln the process unit is
possibly stained by a hand o~ the u~er, or the photo-
sensitive member is possibly damaged mechanically or
~ ~$~
physically, if it is partl~ exposecl. In addition, the
photosensitive layer of zinc oxide, selenium or organic
photoconductor (opc), which constitutes the image bearing
member in the process unit, may be deteriorated, when it
is exposed to the external light. The stain, damage or
deterioration will adversely affect the image formed by
the image forming apparatus with the process unit.
The process unit is relatively frequently placed
into or out of the image forming apparatus during its
service life, since it is replaced with another unit of
different color copy, for example, as described herein-
before, so that it is desirable to ensure the protection
of the photosensitive member.
SUMMARY OF THE INVENTION
According to the present invention, there is pro-
vided a process unit, or an image forming apparatus using
the process unit, the unit being detachably mountable in-
to an image forming apparatus in a predetermined place
thereof, and comprising a photosensitive member; process
means actable on said photosensitive member; a casing
having an exposure opening for allowing light to reach
said photosensitive member from outside thereof; a pro-
tection cover for protecting said photosensitive member;
and means for supporting said protection cover for move-
ment between a closing position wherein it closes theexposure opening and a retracted position wherein it is
retracted from the closing position, said protection
~ 4 --
cover being adapted to be moved, when said process unit
is mounted to the predetermined portion of the main
assembly, by a member of the main assembly associated
with an optical system of the main assembly, from the
closing position to the retracted position. With this
arrangement the image forming member can be protected
from possible stain and damage, when not in use or when
it is exchanged with another process unit.
Further features of this invention will be appar-
ent from the accompanying drawings and following descrip-
tion of a preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a copying apparatu~ according to an
embodiment of the present invention;
Figure 2 shows the copying apparatus of Figure 1
in a different state;
Figure 3 is a partly broken perspective view of a
drum cover operating mechanism of the copying apparatus
of Figure l;
Figure 4 is a partly broken front view of the copy-
ing apparatus of Fi.gure 1, showing the state wherein the
process unit is set in the apparatus, and the drum cover
is opened;
Figure 5 is a partly broken front view of -the copy-
ing apparatus of Figure 1, showing the different state
wherein the drum cover is opened;
Figure 6 is a partly broken perspective view
-- 5 --
seen from the front, of the process unit used with the
copying apparatus of Figure 1:
Figure 7 is a perspective view, seen from the
rear, of the process unit shown in Figure 6:
Figure 8A shows a front view of a shielding
plate in the closed state:
Figure 8B shows a front view of the shielding
plate in the opened state:
Figure 9 shows a cross-section of another
embodiment of the shlelding mechanism:
Figure 10A shows a cross-section of a further
embodiment of the shielding mechanism in the closed
state:
Figure 10B shows a cross-section of the
shieldlng mechanism of Figure 1 OB in the opened state:
Figure 11 shows a cross-section of a yet
further embodiment of the shielding mechanism:
Figure 12 is a perspective view of the process
unit according to a further embodiment of the present
invention:
Figure 13 shows a cross-section of the process
unit of Figure 12:
Figure 14 is a plan view of a part of the
process unit of Figure 12:
Figure 15 is a cross-sectional view of a
part of the process unit of Figure 12, taken along
lines XV-XV of Figure 14: and
4 ~ 4
Figures 16A, 16B, 16C and 16D show cross-
sections of the process units of different types
according to the present invention.
5 DESCRIPTION OF THE PREFERRED EMBODIMENTS
.
Preferred embodiments of the present invention
will now be described in conjunction with the accompany-
ing drawings. The description will be made with respect
to an electrophotographic copying apparatus as an
example of the image forming apparatus of the present
invention.
Figure 1 illustrates a cross-section of a
copying apparatus according to an embodiment of the
present invention. Figure 2 shows the same apparatus
in a different state, wherein the copying apparatus is
opened which will be described in detail hereinafter.
The copying apparatus of Figure 1 includes
a copyboard l for carrying an original to be copied,
the copyboard 1 is made of a transparent material like
glass. The copyboard 1 reciprocates on the rail R in
the directions shown by arrow a. Under the copyboard
1, there is provided an array of image forming elements
2, whlch is effective to project through a slit an
image of the original O to be copied placed on the
copyboard 1, in a focussed state, onto the surface of
photosensitive drum 3 having a organic photoconductor
~opc). The original isilluminated by a lamp L. The
optical path from the lamp to the photosensitive drum
3 is depicted by the refexence numeral 15. ~he photo-
sensitive drum 3 is rotatable in the direction shown
by arrow b. The photosensitive drum 3 is electrically
charged by a corona charger 4 which is effective to
uniformly charge the photosensitive drum 3. The photo-
sensitive drum 3, which is uniformly charged by the
charger 4, is then exposed to the light image through
the array 2 to form an electrostatic latent image
thereon, which is in turn developed by a developing
device 5.
A transfer sheet P, onto which the thus
developed image is to be transferred is fed toward the
photosensitive drum 3 by the feeding roller 6 and the
register roller 7, and receives the toner image from
the photosensitive drum 3 with the aid of the transfer
corona charger 8. The transfer sheet P is then separated
from the photosensitive drum 3 by the separatinq means
13 and transported along a guide 9 bv a roller 9a which
is disposed at a lateral end, to fixing means 10 where
the toner image on the transfer sheet P is fixed. The
sheet P is then dischar~ed out of the apparatus onto a
tray 12.
On the other hand the toner remained on the
photosensitive drum 3 is removed and collected by the
cleaner 14. The apparatus further includes a copyboard
cover U for pressing the original to the copyboard 1,
- 8 -
a fllter 16 for absorbing infrared light or others and
a discharging fan. A shield 52 is fixedly provided to
block the light and located at such a position that a
process unit, which will be described in detail herein~
after, is slightly spaced apart from the shield 52.
The copying apparatus is divisible into two
parts, i.e., upper body 17 and the lower hody 18 which
are pivotably connected by the pin 19. The upper body
is pivotable counterclockwise by a compressed spring S
to open the copying apparatus, as shown in Figure 2.
The upper body 17 contains an illuminating optical
system including the lamp L and the imaging element
array 2, photosensitive drum 3, the developing means
5, the cleaning means 14, which are parts of the image
forming process means. The lower body 18 contains the
feeding roller 9, the transfer corona discharge 8, the
separating means 13, the guide 9, the fixing means 10
and others along the path of the transfer sheet P.
In this embodiment of the present invention,
the photosensitive drum 3 and the process means there-
around such as the developing means 5, cleaning means
14 and the char~er 4 and some others are all contained
in a shielding wall 30a as a unit, to constitute a
process unit 30. Because of this arrangement, when the
photosensitive drum 30 is replaced with another one,
all the process means that are contained ln the unit
are also replaced with new ones~ Thus, the maintenance
9 ~ J~t;~
servicing is much reduced and simpllfiedO The process
unit 30 is mounted into or demounted from the main
body C of the copying apparatus, by sllding the process
uni-t 30 alonq the guiding rails 31 and 32 provided in
the main body. Upon this sliding movement, the process
unit 30 is moved in the direction parallel to the axis
of the photosensitive drum 30. The sliding wall 30a
which constitutes an outer casing of the process unit
30, is effective to block the light and to support the
process means around the photosensltive drum 30 with a
predetermined precision.
The casing 30a of the process unit 30 which
is made of an opa~ue material such as an ABS resin is
provided with an opening 51 at the bottorn thereof, which
exposes the photosensitive drum 3 to allow the transf~r
sheet P to access to the photosensitive drum 3 surface
for the purpose of the image transfer action, when the
process unit 30 is set in the image forming apparatus.
In order to close the opening 51 with the view to
blocking the light to the photosensitive drum 3 and
protecting the same from the possible damage, when the
process unit 30 is out of the image forming apparatus,
a drum cover 20 is provided which ls shown in detail
in Figurs 3. As shown in Figure 3, swingable arms 21a
and 21b are journalled on the shat 30a of the photo-
sensitive drum 3 adjacent to the opposite ends of the
photosensitive drum 3. To the other ends of the arms
21a, longitudinal ends of the drum cover 20 are
pivotably supported by pins 33 at one lateral end of
the cover 20. At ~he other lateral end of the drum
cover 20, the longitudinal ends of the drum cover 20
are also pivotably supported by pins 34 to the addl-
tional swingable arms 22a which are rotatahly supported
on a shaft 23 which extends codirectionally with the
dxum shaft 3a. At an end of the shaft 23 a lever 25
is fixed. The arms 21a and 21b are urged counterclock-
wise by a spring 24. Deslgnated by reference numeral30d in Fi~ure 3 is a part of the inner casing of the
process unit 30.
When the lever 25 is rotated clockwise by the
mechanism which will be described heireinafter, the shaft
23 rotates clockwise to move the drum cover 20 through
the swingable arms 22a and 22b to retract the drum cover
20 so that it retracts fxom the closing position, thus
exposing the photosensltive drum 3.
To automatically open the cover 20, the lower
body 18 of the image forming apparatus has a fixed
projection 26. When the process unit 30 is set in
place in the image formlng apparatus, and the upper
body 17 is closed, the projectlon 26 pivots the lever
25 in the clockwise direction to retract the drum cover
20 from near the photosensitive drum 3 surEace to un-
cover the drum opening 51 to expose the drum surface,
thus enabling the image forming operation, as ~hown in
~s'~
Figure 4.
When the upper body 17 is opened as shown in
Figure 5, the lever 25 disengages from the projection
26, the spring 24 having an end beared on a projection
24a formed on the inner casing 30d and the other end
beared or a projection 24b formed on the arm 21a, pivots
the swingable arms 21a and 21b in the counterclockwise
direction to move the drum cover 20 to the neighbourhood
of the drum 3 surface exposed, until it compLetely
covers the opening 51. Thus, whenever the upper body
17 is opened, the cover 20 automatlcally closes the
opening 51 to block the light otherwise entering the
photosensitive drum 3, thus preventing the influence
of the light to the photosensitive drum 3 and also
preventing the possible mechanical or physical damage
thereto.
In the foregoing embodiment, a part of the
image forming apparatus is dlvislble, and the photo-
sensitive drum 3 is shielded from the external light
through the opening 51 which allows the image transfer
operation, when the image forming apparatus is divided.
The dividing is carried out, when the image forming
apparatus is subjected to the malntenance servicing
or when the transfer sheet P i~ ~ammed. So, at such
tlmes, the photosensitive drum 3 ls protected from the
external light without operator's paying attention to
the protection.
- 12 -
The removal of the process unl t 30 from the
ima~e forming apparatus wlll now be described. When
it is to be taken out of the apparatus, it is flrst
divided as shown in Figure 2. Then, the process unit
30 is pulled outwardly along the guide rails 31 and 32
in the d1rection parallel to the drum shaft. I~ should
be noted that the opening 51 has been closed by the
drum cover 20 as described herelnbefore.
However, he process unit 30 has another
opening. That is the image exposure aperture 27 forme~
in the casing 30a at the position opposing the imaging
element array 2 to al1ow the lmage light to reach the
photosensitive drum 3 ~urface when in use. Since the
aperture 27 is near the surface of the photosensltive
drum 3, the photosensitive drum 3 surface is readily
influenced by the external light. For example, when
the process unit 3 is ta~en out and left on a table for
a w~ile, the photosensitive drum 3 may come to have a
llght memory because of the natural light or other
illuminating liqht existing around the table, which may
reach the surface of the photosensitive drum 3 through
the aperture 27. In ~ddition, the surface may be
damaged bv something entering through the aperture 27.
Further, foreign matters, such as dust, small pleces or
the like, may enter and damage the surface of the
photosensitive drum 3 during the subsequent lmage
forming operation in which the photosensitive drum 3
- 13
rotates.
To solve this problem, the aperture 27 is
provlded with a shield ~or blocking the light, which
will be described in detail in conjunction with Figures
6 and 7. Figure 6 shows a perspective view, seen from
the upper front side, of the process unit 30 of an
embodiment of the present invention, whlch has been
taken out of the image forming apparatus body C.
Figure 7 shows a perspectlve view of the same seen from
the upper rear side The process unit 30 has a grip
30b for pulling the process unlt 30 out of the image
forming apparatus body C and another grip 30C for
carrying the process unit 30.
As shown in Figure 7, the process unlt 30 has
at its rear side an indexing pin 36 for mounting itself
at a correct position in the image forming apparatus.
Also, the process unit 30 has at the same side a
connector 37 for supplying high voltage power to the
corona charger 4 in the process unit 30, a gear 38 for
transmitting the driving power from the image forming
apparatus body C to the photosensitive drum 3 of the
process unit 30 and a connector 39 for applying a bias
voltage to the developing means 5. The gear 38 includes
projected portions and adjacent recessed portions which
are adapted to mesh with the recessed portions and
projected portions of a gear, not shown, of the image
forming apparatus.
The upper part of the wall 30a of the process
unit 30 ls provided with a recess 30e having a bottom
30f, in which an aperture Z7 for the image light pro-
jection is formed. One of the side wall 30g of the
recess 30e is prvvided with a shaf~ 28c at the upper
portion thereof. To the shaft 28c, a cover or a shield
28 of a rigid material for blocking light is rotata~ly
supported. The shield 28 has the dimension similar to
that of the bottom 30f of the recess 30e to completely
cover the upper opening 30h of the recess 30e. The
shield 28 rotates as shown by arrow c in Fi~ure 6 in
response to mounting and demounting of the process unit
30 into and out of the image forming apparatus body C.
The action of the shield 28 will be described
in detail in conjunction with Figures 8A and 8B, which
show an enlarged front view of the process unit 30.
The shield 28 is urged upwardly by a spring 49 having
an end fixed to the process unit 30 body by a pin 40a
and the other end fixed to that lateral end which is
remote from the shaft 28, by a pin 28b, so that the
opening 27 i5 closed thereby, when the process unit 30
is out of the main body C of the image forming apparatus.
The pin 40a is located at the ~ame level as, or at a
higher level than, the pin 28b so that the sprlng 40
force $s effectlve to ur~e the shield 28 to the stopper
30i, thus closing the opening 30h. Therefore, any
external light cannot enter through the aperture 23
- 15 -
so tha~ ~he photosensitive drum 3 ls shielded from the
~xternal light therearound. Thus, the possible
occurrence of the light memory ln the photosensitive
drum 3 is prevented. It is also protected from a
S possibility of mechanical or physlcal damage to the
photosensitive drum 3. Additionally, ~he foreign
matters such as dust or the like canno~ enter, through
the opening.
The action of the shield 28 when the process
unit 30 is mounted into the apparatus body C will now
be described. The shield cover 28 has an integral tab
28a, at the rear side end, which is inclined downwardly
away from the shield 28, as shown in Figures 6 and 7.
The apparatus body C has a guiding projection 41
engageable with the tab 28a, as shown in Figure 6O
When, therefore, the process unit 30 is belng mounted
into the apparatus body C, the tab 28a enga~es to the
guiding projection 41, as shown in Figure 6, and with
the insertion of the process unit 30, the shield 28
is pushed downwardly by the guiding projection 41 so
that the shield 28 rotates in the clockwise direction
about the shaft 28c as shown in Figure 8B. Thus, when
the process unit 30 is placed in the predetermlned
position in the apparakus body C, the aperture 27
25 opens as shown in Figure 8B, so that the llght from
the imaging element array 2 can reach the photosensi-
tive drum 3 to allow the imagewise exposure of the
16 -
photosensitive drum 3.
When the process unit 30 is taken out of the
image forming apparatus body C, the shleld 28 returns
to the horizontal position automatically by the spring
40 force to close the opening 27.
As for materials of the wall 30a, the cover
20 for the light blocking and the shield 28 for the
same purpose, polyphenylene oxide resin, polycarbonate
resin, ABS resin, metal and rubber which are opaque
are suitable. In addition, transparent materlal is
usable, if it absorbs or reflects the light of the
wavelength to which the photosensitive layer of the
photosensitive drum 3 is sensltive.
Figure 9 shows another embodiment of the
present invention. In the foregoing em~odiment, the
shield 28 is urged by the spring 40. In the embodiment
of Figure 9, a magnetic repell~ng and attractlng forces
are utilized, in place of the spring force. Otherwise,
the structure of thls embodiment is the same as the
foregoing one. When the process unit 30 is taken out
of the image forming appaxatus body C, the shield 28
is released from the guiding projection 41 of the
image forming apparatus C. Then, the shield 28 is
raised by the repelling magnetic force between a
magnet 43 provided on one end of the shield 28 and
the magnet 42 provided on the lower side wall 30g
portion of the recess 30e. The raised shield 28 is
- 17 ~ 3
then lifted up by the magnetlc attracting force betwee~
the magnet 43 and another magnet 44 provided adjacent
to the openiny 30h, to take its horizontal positlon,
thus closing the aperture 27.
Figures 1 OA and 10B show a further embodiment
of the present invention, wherein the shield is formed
by flexible shield plates 45 and 46 made of a flexible
rubber sheet or a synthetlc re~ln sheet which has a
small surface friction coefficient and which can block
the light of the wavelength to which the photosensitive
drum 3 is sensitive. When the process unit 30 is out
of the image forming apparatus body C, the shield
plates 45 and 46 are partly overlapped to entirely
cover the opening 30h above the image exposure aperture.
27 to prevent the light from entering the process unit
30, and therefore, reaching the photosensitive drum 3.
When, on the other hand~ the process unit 30
is mounted in place in the image forming apparatus
body C, the guide 47, provided on the image formlng
apparatus at a position opposing the aperture 27 when
the unit is being set in, bends downwardly the shield
plates 45 and 46 to open the shield, and the parts of
the shield plates 45 and 46 which have been in the
image forming apparatus body C are kept open by the
array 2 of the imaging element, 50 that the light
from the imaging element array 2 can reach the photo-
sensitlve drum 3.
18 -
In any of the foregoing e~bodimen~s, the
guides 41 and 47 are provided at a front side of the
apparatus so that they do not interfere with the
aperture 27 of the process unit 30 when it is set in
S place.
Figure 11 illustrates a further embodiment
of the present invention, wherein a side cross-section
is shown. The shield 48 is of bellows structure.
When the process unit 30 is out of the apparatus body
C, the shielding bellows close the aperture 27 to
prevent the light memory which otherwise occurs in the
photosensitive drum 3 and to protect the pho~osensitive
drum 3 from a possible damage. Wh0n the process unit
30 is brought into the apparatus body C, a member 49
of magnetic material mounted on an end of . the shield-
ing bellows 48 abuts the magnet stopper S0 of the
apparatus body C. With the subsequent insertion of
the process unit 30 into the apparatus body C, the
magnetic member 49 slides above the aperture 27, and
the shielding bellows contract to open the aperture
27.
When the process uni~ 30 is removed from
the apparatus body C, the magnetic member 49 is kept
contacting to the magnet stopper 50 by the magnetic
force therebetween, so that the contracted bellows
are expanded with the pulling-out of the process unit
30, untilthe magnetic member 49 is attracted to another
- 19 -
magnet 51 fixed on the process unl~ 30 at an end
thereof, thus rocking the shi~ld 48 at its closlng
position.
Figure 12, 13, 14 and 15 illustrate a further
S embodiment of the present invention. Figure 12 shows
a perspective view of a process unit 63 to which the
present invention is embodied. Figure 13 is a cross-
sectional view of the process unit 63 of Figure 12.
Figure 14 is a plan view of the same process uni~ 63.
Figure 15 is a cross-sectional view of a part of the
process unit 63 and a part of the image forming
apparatus body C when the process unit 63 is set in
place therein.
The process unit 63 is moved in the direction
shown by arrow e, when it is inserted into the apparatus
body C. To the upper part of the process unit 63,
more particularly, above the image exposure aperture
68, two black flexible sheets 69a and 69b of a
synthet~c resin are bonded to the process unit 63.
The unbonded parts of the sheets are partly overlapped
to prevent the light from leaking into the process
unit 63. For the facilitation of the insertion of
the process unit S3 into the apparatus body C, which
will be described hereinafter, ends of the sheet 69a
and 69b are bent downwardly as shown by the reference
numerals 69c and 69d. This will be clearly understood,
referring to Figures 12 and 14. The sheets 69a and
- 20 -
69b are so shown that the sheet 69a is over the sheet
69b, but this may be inversed. The sheets 69a and
69b together completely cover the exposure aperture
68, and further they block the lateral light entering
substantially completely by the bent portions 69c and
69d.
When the process unit 63 of this embodiment
is brought into the apparatus body C, the concave-up
portion 65a of the apparatus body C acts on the sheets
69a and 69b. The concave-up portion 65a is a part of
the light blocking wall 65 of the process unit 63 and
~unctions to support a dust proof glass 66 which protect
from dust the imaging element array 2 which extends
into the concave-up portion. Since the sheets 69a and
69b are of flexible materlal, they are bent by the
concave-up portlon 65a, as shown in Figure 15. The
concave-up portion 65a is long enough to cover the
entire length of the sheets 69~ and 69b, that is, it
has the same length or longer, the portions which are
bent with the insertion of the process unit 63, and
upon setting the process unit 63 in place, the sheets
69a and 69b, over their entire length, are kept bent
downwardly. Thus, the lateral end portions of the
sheets 69a and 69b no longer overlapped, so that the
aperkure 68 is opened to allow the light image of the
original to be copied to reach the photosensitive drum
3 surface.
- 21 ~ 3~
When, on the other hand, the process unit 63
is taken out o~ the appara~us C, the sheets 69a and 69b
restore their overlapping position because they are of
flexible and resilient material. That is, with the
pulllng-out of the process unit 63, the sheets 69a and
69b are successively bent back to its original position,
so that the sheets 69a and 69b take the closing posi-
tion, as shown in Figure 13.
The bent portions 69c and 69d of the
respective sheets 69a and 69b are effec~ive to make
easier the initial bending of the sheets by the concave-
up portion 65a upon insertion of the unit.
The part of the optical means which acts on
the sheets 69a and 69b is the wall constituting a part
of the image ~xposure optical system in the embodiment.
This is not limiting, but the array 2 itself, a support
for the array or a support for the light source may be
used. Therefore, a structure for the optical means
actable on the process unit may be usable.
As described in detail in the foregoing, the
process unit i5 provided with a shielding cover which
automatically opens and closes the aperture of the
process unit in response to the in~ertion into and
pulling out of, the image forming apparatus hody C,
respectively, thus ensuring the protection of the
photosensitive drum from the deterioration by the
external light and from the posslbility of the
$~
- 22 -
mechanical or physical damaye thereto.
Although the foregoing explanations have been
made with the embocliments wherein the process unlt is
completely taken apart from the image forming apparatus
body C, the pxesent invention ls applicable to the
case where the unit can be partly drawn out but cannot
be pulled apart. The shield or light blocking assembly
is applicable not only to the im~ge exposure aperture
but also to an aperture for the pre-exposure or an
aperture for the whole surface exposure which may be
preferable or necessary because of peculiarity of the
image forming process usedt and also applicable to an
aperture for a blank exposure, as the case may be.
The foregoing embodiments employ the lmage
bearing members having an organic photoconductor,
selenium (Se) or a zinc oxide photoconductor, but the
materials are not limiting, and other photosensitive
layers may be used. Additionally, the present invention
is not llmited to the case where the image bearing
member has a photosensitive layer, but the image beariny
member can be an insulating member, in which the main
purpose of the cover is the protection from the mecha~
nical or physical damage. The image bearing member is
not limited to a drum or cylinder type, but lt may be
o~ an endless belt entrained on pulleys.
The developing method is not limiting, either.
It may be magnetic brush development, cascade development,
- 23 -
fur brush development, powder cloud development or
other types of development.
The method or mechanism of the cleaning of
the image bearing member is not limlted to the blade
cleaning, but fur brush cleaning, roller cleaning or
web cleaning is usable.
The imaging element is not limited to the
array of the small dlameter imaging elements each
having a relatively short focal length. It may be
an ordinary imaging lens or bar lenses.
The image forming process is not limiting.
It may be a so-called Carlson process, NP process
~USP 3666363) or PIP (Persistent Internal Polarization)
process.
Although the foregolng embodiments of the
present invention include the process unit which
contains not only the photosensitive drum but also
a developing device, cleaner and charger, as the
process means, the present invention is not limited
to this arrangement. For example, as shown schemati-
cally in Figures 16A, 16B, 16C and 16D, the process
unit 30 may contain as a unit the developing device
5 and photosensitive drum 3, as the process means
~Flgure 16A); may contain as a unit the cleaner 14
and photosensitive drum 3, as the process means
(Figure 16B); may contain as a unit the charger 4,
developer 5 and photosensitive drum 3 ~Figure 16C);
-- 24 --
or may con~ain as a unit the charger 4, cleaner 14 and
photosensitive drum 3 (Figure 16D). ~s described
hereinbefore the image bearing member is not limited
to photosensitive drum. The process unit, therefore,
S may contain only a part or all of the process means.
The process means actable on the image bearing member,
in the foregoing embodiments, are the array of the
imaging elements, corona charger, developer, transfer
corona discharger, sheet separating means and cleaner.
The image bearing member or another part of
the pxocess unit may be constructed as being detachable
from the unit.
According to the present invention, as
described above, the image bearing member can b~
surely protected by a shield or shields preventing
the deterioration of or damage to the image bearing
member.
While the invention has been described with
reference to the embodiments disclosed herein, it is
not confined to the details set forth and the present
application is intended to cover such modifications
or changes as may come within the spirit of the
improvements or the scope of the Claims.
