Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
5~3~
-- 1 --
A REPRODUC ING MACHINE
This invention relates generally to a reproduc-
ing machine, and more particularly concerns an electro-
photographlc printing machine having a stationary photo-
conductive member and a stationary original document.
The process of electrostatographic printing
requires the formation and utilization of an electro-
static latent image for the purpose of recording and
reproducing patterns in viewable form. Electrostato-
graphic printing includes electrophotographic print-
ing and electrographic printing. In electrophotographic
printing, electromagnetic radiation is used to form
an electrostatic latent image on a photoconductive
member. An elec~rographic printing machine employs
an insulating medium to form, without the aid of elec-
tromagnetic radiation, an electrostatic latent image.
~ Generally, the process of electrophotographic printing
includes charging a photoconductive member to a sub-
stantially uniform potential to sensitize the surfacethereof. The charged portion of the photoconductive
surface is exposed to a light image of an original
document being reproduced. This records an electro-
static latent image on the photoconductive member corres-
ponding to the informational areas contained withinthe original document being reproduced. After the
electrostatic latent image is recorded on the photocon-
ductiYe member, the latent image is developed by br ing-
ing particles o~ a developer mix into contact there-
with. The developer mix particles are attracted tothe latent image forming a particle image on the photo-
conductive member. The particle image is then trans-
ferred from the photoconductive member to a copy sheet.
Finally, the copy sheet is heated to permanently affix
the particles thereto in image configuration. This
general approach was disclosed by Carlson in U~ S.
~.
~45~
Patent No. 2,297,691 and has been further amplified
and described in many related patents in the art.
In electrophotographic printing, the electro-
static latent image comprises electrostatic surface
charges. These surface charges may be transferred to
or reproduced upon a dielectric surface. The techni-
que for accomplishing charge transfer is referred to
as a TESI process, from transfer of electrostatic images.
Hence, electrostatic latent images may be transferred
to another surface prior to development. The material
to which the electrostatic latent image is transferred
must, of course, be capable of retaining the image,
i.e. it must be a good insulator. Thus, electrostatic
latent images may be transferred to the dielectric coated
paper. The transferred images can be developed by the
same methods hereinbefore described for developing the
electrostatic latent images recorded on the photoconduc-
tive member. However, since the charge on the dielec-
tric surface is not dissipated by exposure to light,
it is not necessary to shield the image from light during
development. After the electrostatic latent image trans-
ferred to the dielectric sheet has been developed, the
powder image thereon may be fused thereto forming a
finished copy sheet.
Various types of electrostatographic printing
machines have hereinbefore been employed to utili~e
the foregoing processes. The following disclosures
appear to be relevant:
U. S. Patent No. 2,825,814
Patentee: Walkup
Issued: March 4, 1958
U. S. Patent No. 2,833,648
Patentee: Walkup
Tssued: May 6, 1958
~B~59~
U. S. Patent No. 2,937,943
Patentee: Walkup
Issued: May 24, 1960
U. S. Patent No. 2,975,052
Patentee: Fotland et al.
Issued: March 14, 1961
U. S. Patent No. 2,982,647
Patentee: Carlson et al.
Issued: May 2, 1961
U. S. Patent No. 3,574,455
Patentee: Mix, Jr.
Issued: April 13, 1971
The relevant portions of the foregoing disclo-
sures may be briefly summarized as follows:
The Walkup patents disclose a photosensitive
plate closely spaced to an electrode with an insulating
web passing therebetween. Voltage is induced between
the plate and electrode to cause the electrical charge
pattern recorded on the plate to migrate to the web.
The web is developed and the resultant powder image
fused thereto so as to form a copy of the original docu-
ment.
Fotland et al. describes the formation of an
electrostatic latent image on a photosensitive element.
The photosensitive element is brought into contact with
a plate consisting of an electrically insulating mater-
ial and an electrically conductive material. Electrical
contact is established between the conductive layer
of the photosensitive element and the conductive mate-
rial of the plate. As a result, the latent image is
transferred to the insulating material of the plate
s~3
-- 4
which is developed into a visible imaye.
Carlson et al. teaches the transfer of an electro-
static latent image which has been previously formed on
a first insulating surface to a second insulating surface
in contact therewith by producing an intense electrical
field between the surface and subsequently separa-ting the
surfaces.
Mix, Jr. describes a photoconductive drum moving
in a planetary motion so that a point on the drum's surface
has ~ero velocity when adjacent to a particular functional
station. This permits incremental printing upon the paper.
This movement of the drum permits the paper to be moved
freely between printing stations.
An aspect of the invention is as follows:
A reproducing machine, including:
means for supporting substantially stationarily
an original document being reproduced;
a photoconductive member;
means for recording successive incremental
portions of the original document as a latent image on
said photoconductive m~mber; and
means for translating said photoconductive member
and said recording means relative to said supporting means
with the portion of said photoconductive member having
an incremental portion of the original document recorded
thereon as a latent image being substantially stationary
relative to the original document being reproduced and
the other portions of said photoconductive member moving
relative to the original document.
Other features of the present invention will
become apparent as the following description proceeds and
upon reference to the drawings, in which:
Figure 1 illustrates a schematic elevational
view of one embodiment of the reproducing machine of
the present invention employing a photoconductive drum~
s~
- 4a -
Figure 2 shows a schematic elevational view of
another embodiment of the reproducing machine of the present
invention uslng a photoconductive belt;
and
Figure 3 depicts a schematic eleva-tional view
of still another embodiment of the reproducing machine
'^ ~"
:,
of the present invention using a photoconductive belt.
While the present invention will hereinafter
be described in connection with various embodiment
thereof, it wi]1 be understood that it is not intended
to limit the invention to these embodiments. On the
contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included within
the spirit and scope of the invention as defined by
the appended claims.
For a general understanding of the reproducing
machine of the present invention, reference is made
to the drawings. In the drawings, like reference
numerals have been used throughout to designate identi-
cal elements. The drawings depict various embodiments
of illustrative electrophotographic printing machines
incorporating the features of the present invention
therein. As shown, the drawings schematically depict
the various components of each of these electrophoto-
graphic printing machines which have the various fea-
tures of the present invention incorporated therein.Inasmuch as the art of electrophotographic printing
is well known, the various processing stations employed
in the printing machines will be shown herein schema-
tically and their operation described with refer-
ence thereto.
Re~erring now to Figure 1, the embodiment ofthe electrophotographic printing machine depicted there-
at includes a drum, indicated generally by the reference
numeral 10, having a photoconductive surace secured
to a conductive substrate. Drum 10 is mounted rotata-
bly on a carriage (not shown) which translates in the
direction of arrow 12. As drum 10 translates in the
direction of arrow 12, it rotates about its longitudi-
nal axis in the direction of arrow 1~. In this way,
the drum velocity at the point of exposure is essentially
zero. Thus, the photoconductive surace, at the point
5~3
-- 6
of exposure to a light image of an oriyinal document
has zero velocitv.
At charging station A, a corona generating device,
indicated generally by the reference numeral 16
translates with the drum so as to charge successive
portions of the pho~oconductive surface of drum 10 to a
relatively high, substantially uniform potential.
Corona generating device 16 is mounted on the carriage
supporting drum 10 rotatably so as to translate
therewith.
Next the charged portion of the photoconductive
surface of drum 10 is illuminated at exposure station
B. The original document 18 is positioned face dow~
upon a stationary transparent platen 20. The exposure
system includes a lamp 22 and lens strip ~4 mounted on
the carriage supporting drum 10 so as to translate
therewith. As lamp 2~ translates, it illuminates
incremental widths of original document 18. The light
rays transmitted from the original document 18 are
transmitted through lens strip 24 from a light image
thereoE. This light image selectively discharges the
charged portion of the photoconductive surface of drum
10 so as to form an electrostatic latent image thereon.
The instantaneous velocity o~ the photoconductive
surface of drum 10 is zero at exposure station B. In
operation, as lamp 22 and lens strip 24 translate
relative to original document 13, successive charged
portions of the photoconductive surface are positioned
at exposure station ~ having a zero velocity relative
to the stationary original document~ This permits wide
latitudes in system operations. A suitable lens strlp
optical system is described in U.S. Patent No.
3,544,190 issued to Moorhausen in 1970.
Next, drum 10 rotates the electrostatic latent
image recorded on the photoconductive surface thereof
;.~`;~'
s~
to transfer station C. At transfer station C, the
electrostatic latent image recorded on the photocon-
ductive surface of drum 10 is transferred to a dielec-
tric sheet 26. A conveyor (not shown) translates the
dielectric sheet in the direction of arrow 12 at twice
the linear ve]ocity of drum 10. During the translation
of both drum 10 and dielectric sheet 26 in the direction
of arrow 12, drum 10 continues to rotate in the direc-
tion of arrow 14 S3 as to transfer incremental electro-
static latent images onto dielectric sheet 26. ~hendielectric sheet 26 reaches the end of movement, i.e.
one half a revolution of drum 10 beyond the end of
platen 20, as shown by the dotted representation of
drum 10, the entire electrostatic latent image has trans-
ferred thereto. The relative linear velocity betweendrum 10 and dielectric sheet 26 at the point of contact,
is essentially zero. Preferably, dielectric sheet 26
may be of any composition suitable for electrographic
recording. By way of example, Mylar, polystyrene and
polyethylene are examples of coatings which may be
formed on plain paper to produce a dielectric sheet
capable of retaining an electrostatic latent image
thereon.
At transfer station C, the electrostatic latent
image is transferred from drum 10 to dielectric sheet
26. Inasmuch as the charge on dielectric sheet 26 is
not dissipated by exposure to light, it is not necessary
to shield the image from light during the subsequent
processing steps. Dielectric sheet 26 contacts an elon-
gated conductive rubber roller 28. A non-condurtive
rubber pad 30 is positioned prior to roller 28 in the
direction of rotation o~ drum 10, as indicated by arro~
14. Both roller 28 and pad 30 are mounted on the trans
lating carriage supporting drum 10 rotatably. Prefer-
ably, roller 28 is electrically grounded provided thephotoconductive surface o~ drum 10 is maintained at
c~ /h a~
15~
a sufficiently hiqh potential~ Alternativel~, if the
photoconductive surface of drum 10 is at a lo~,ler
potential, voltage source electricall~ couples roller
30 to the conductive backing of drum 10. The voltage
source applies an electrical field between the
conductive backing of drum 10 and roller 30. The
electrical field applied by the voltage source is of a
suitable magnitude and polarity to transfer the
electrostatic latent image from the photoconductive
surface of drum 10 to the dielectric sheet.
Preferably, the potential difference between the
conductive backing of drum 10 and conductive roller 28
is about 1,000 volts. Various techniques have
hereinbefore been described teaching the process of
-transferring an electrostatic latent i~age from a
photoconductive surface to a dielectric sheet. Typical
techniques are described in U.S. Patent No. 2~833,648
issued to Walkup in 1~58, U.S. Patent No. 2,937,943
issued to Walkup in 1960, U.S. Patent No. 2,975,052
issued to Fotland et al, in 1961, U.S. Patent No.
2,982,647 issued to Carlson in 1961, and U.S. Patent
No. 3,055,006 issued to Dreyfoos et al in 196~.
Preferably~ the carriage supporting drum 10 and
the various processing stations translating therewith
is mounted on a drive screw and bearing rod arranged
with their axes in a parallel and spaced relationship
on a base plate. A motor, coupled to a gear box, turns
the drive screw which in turn translates the carriage
in the direction of arrow 12.
After the electrostatic latent ima~e is
transferred to the dielectric sheet, a conveyor (not
shown) advances the dielectric sheet to development
station D. Development station D is positioned after
platen 20. Hence, electrostatic transfer is terminated
when drum 10 reaches the end of its travel, i.e. one
half
S<~3
a revolution of drum 10 beyond the end of platen 20.
Development station D includes a magnetic brush devel-
opment system, indicated genera]ly by the reference
numeral 32. The maqnetic brush development system
advances magnetic particles into contact with the elec-
trostatic latent image on dielectric sheet 26. A hopper
34 stores a supply of magnetic particles 36 therein.
Magnetic particles 36 are dispensed ~rom hopper 3~ onto
tubular member 38. Preferably, tubular member 38 is
made from a non-magnetic material, such as aluminum.
An elongated magnetic member 40 is mounted rotatabLy
interiorly of tubular member 38. Tubular member 3~
is stationary and as magnetic member 40 rotates, mag-
netic particles 36 are transported into contact with
the electrostatic latent image formed on dielectric
sheet 26.
After the electrostatic latent image formed
on dielectric sheet 26 has been developed with magnetic
particles, a conveyor (not shown) advances dielectric
sheet 26 to fusing station E having a fusing system indi
cated generally by the reference numeral 42. An exem-
plary fusing system 42 is a cold roll pressure system
including a pair o~ rollers 44 and 46. The dielectric
sheet with the powder image thereon passes between rollers
44 and 46. Rollers ~4 and 46 apply pressure on the
powder image to permanently af~ix it to the dielectric
sheet. Preferably, rollers 44 and 46 are made from
chrome plated as stainless steel. Rollers 44 and 46
rotate in a suitable direction so as to continue to
advance dielectric sheet 26. ~fter fusing, dielectric
sheet 26 advances to the catch tray (not shown)~ When
the sheet is in the catch tray, it may be subsequently
removed therefrom by the machine operator.
The process heretofore described is only one
embodiment of the reproducing machine of the present
invention. Turning now to Figure 2, there is shown still
-- 10 --
another embodiment thereof. As shown in Figure 2, photo-
conductive we~ or belt 48 has one end thereof secured
to the frame of the printing machi.ne with the other
end thereof wound about a take-up spool 50. Belt 48
is entrained about roller 52 which is mounted on a mov-
able carriage (not shown) so as to translate in the
direction of arrow 54. The carriage may be driven in
the manner heretofore described with reference to the
embodiment of Figure l or by any other suitable means.
As roller 52 translates in the direction of arrow 54,
take-up spool 50 rotates in the direc-ti.on of arrow 56
so as to take~up belt 4~ as roller 52 translates in
the direction of arrow 54. Once again both the photo-
conductive belt and original document are stationary
at the point of exposure. Initially, charging station
A passes over successive segments of the photoconductive
belt. Charging station A includes a corona generating
device, indicated generally by the reference numeral
58, which charges the photoconductive surface of belt
48 to a relatively high substantially uniform potential~
Corona generator 58 is mounted on the carriage trans-
la-ting roller 52 so as to move therewith to continuously
charge segments of belt 48.
Thereafter, exposure station B passes over
the charged portions of belt 48. At exposure station
B, an original document 60 is positioned face-down on
a stationary transparent platen 62. Exposure station
B includes lamps 64 and lens strip 66 mounted on the
carriage supporting roller 52. ~ence, as lamp 64 ad-
vances in the direction of arrow 54, it illuminatesincremental width strips of original document 60. The
light rays transmitted from these incremental width
strips pass through lens strip 66 to form a li~ht image
thereof which is projected onto successive charged por-
tions of photoconductive belt 48. This forms an electro-
static latent image corresponding to the original docu-
.
ment being illuminated.
Next, as roller 52 translates in the directionof arrow 54, the electrostatic latent image recorded
belt 48 pass through transfer station C. At transfer
station C, the electrostatic latent image recorded on
belt 48 is transferred to a dielectric sheet 68. The
dielectric sheet advances at twice the linear velocity
of roller 5~. In this way, the relative linear velocity
between the photoconductive surface of belt 48 and the
dielectric sheet, at the point of contac~, is zeroO
Dielectric sheet 68 passes between conductive rubber
roller 7G and photoconductive belt 48. Preferably7
roller 70 is electrically grounded. Alternatively,
a voltage source may be connected between electrode
70 and the conductive backing of belt 48. The voltage
source applies an electrical field between the conduc-
tive backing and electrode 70~ The electrical field
supplied by the voltage source is of a suitable magni-
tude and polarity to transfer the electrostatic latent
image from the photoconductive surface of belt 48 to
the dielectric sheet. A non-conductive rubber pad 72
is disposed prior to roller 70. Roller 70 and pad 72
are also secured to the carriage supporting roller 52
so as to translate therewith. Alternatively, roller
70 and pad 7~ may be mounted stationarily, at any point
along the path of movement of roller 52. Preferably,
in this configuration, roller 70 and pad 72 are located
just prior to take-up roller 50, i.e. just prior to
the lead edge of the electrostatic latent image recorded
on the photoconductive surface of belt 48 being entrained
thereabout. This enables the dielectric sheet feeder
to be positioned beneath belt 48 reducing the overall
size of the printing machine. After the electrostatic
latent image is transferred to the dielectric sheet,
the dielectric sheet advances to development station
D.
5~
- 12 -
~ t development station D, a magnetic brush
~evelopment system, indicated generally by the reference
numeral 74, advances magnetic particles into contact
with the electrosta~ic latent image ~ormed on the di-
electric sheet. Preferably, the developer material,i.e. the magnetic particles, is a single component
development material. Magnetic brush development system
74 includes a hopper 76 for holding a supply of magnetic
particles 78 therein. The magnetic particles are dis-
pensed from the hopper onto stationary tubular member80. Preferably, tubular member 80 is made from a non-
magnetic material such as aluminum. An elongated mag-
netic member 82 is mounted rotatably interiorly of
tubular member 80. In this manner, a magnetic field
is created which attracts the magnetic particles to
tubular member 80. ~s magnetic member 82 ro~ates, the
magnetic particles are transported into contact with
the electrostatic latent image formed on the dielectric
sheet.
~fter the electrostatic latent image formed
on the dielectric sheet has been developed with magnetic
particles, the dielectric sheet is advanced to fusing
station E. Fusing station E, indicated generally by
the reference numeral 84, includes a pair of rollers
86 and 88. The dielectric sheet with the powder image
thereon passes between rollers 86 and 88. The rollers
are preferably made from chrome plated stainless steel
or any other material which can apply sufficient pres-
sure to permanently affix the powder image to the di-
electric sheet.
After fusing, a conveyor (not shown) advancesthe dielectric sheet with the powder image permanently
affixed thereto to a catch tray (not shown). In the
catch tray, the dielectric sheet, i.e. the finished
copy sheet, may be readily removed therefrom by the
machine operator.
Referring now to Figure 3, there is shown sti]l
another embodiment of the reproducing machine of the
present invention. The embodiment depicted in Figure
3 also employs a photoconductive belt. As shown there
at, belt 90 advances from a supply spool 92 about roller
94 onto a take-up spool 96. Roller 94 is mounted on
a carriage so as to translate in the direction of arrow
98. As roller 94 translates in the direction of arrow
98, take-up spool 96 rotates so as to ta~e up any slac~
in the photoconductive belt. However, when roller 94
returns to its initial position, the same initial seg-
ment of the photoconductive belt is disposed beneath
the platen supporting the original document. ~ence,
the same segment of the pho-toconductive belt is con-
tinually reused to produce a multiplicity o copies.After many thousands of copies have been made, this
segment of the photoconductive belt may become fatigued.
- In order to obviate this problem, supply spool 92 oper-
ating in conjunction with take-up spool 96 will advance
a new segment of photoreceptor material ~hich, in turn,
is also entrained about roller 94~ With roller 94 fixed
in the initial position, take-up spool 96 rotates to
advance a new section of the photoconductive belt 90
from supply spool 92 into its operative position. Once
again, photoconductive belt 90 and the original docu-
ment are stationary during the exposure process.
Initially, charging station A passes over suc-
cessive portions of photoconductive belt 90. At charg-
ing station A, a corona generating device, indicated
generally by the reference numeral 98, charges the
successive portions of the photoconductive surace of
belt 90 to a relatively high, substantially uniform
potential. Corona generating device 98 is mounted on
the carriage supporting roller 94 so as to translate
therewith.
At exposure station B, an original document
s~(~
- 14 -
104 is positioned on a stationaey transparent platen
106. The exposure station includes lamps 108 and lens
strip 110 secured to the carriage translating idler
roller 94. As lamp 108 translates in the direction
of arrow 100, it illuminates incremental widths of
original document 104. The incremental width light
rays transmitted from document 104 pass through lens
strip 110 so as to form an incremental width light ima~e
thereof. These light images, in turn, are projected
onto successive charged portions of photoconductive
belt 90 so as to selectively discharge these portions.
This records an electrostatic latent image on photo-
conductive belt 90.
Next, electrostatic latent image recorded on
photoconductive belt 90 is transferred to dielectric
sheet 112 at transfer station C. Dielectric sheet ad-
vances in the direction of arrow 100 at twice the linear
velocity of roller 94. In this manner, the relative
linear velocity between roller 94 and dielectric sheet
112 is moving at zero velocity at the point of contactO
Dielectric shee-t 112 passes between photoconductive
belt 90 and a conductive rubber roller 114~ Prefer-
ably roller 114 is electrically grounded. ~owever,
in the alternative, a voltage source may be connected
between roller 114 and the conductive backing of photo~
conductive belt 90. The electrical field applied by
the voltage source is of a suitable magnitude and po-
larity to transfer the electrostatic latent image from
the photoconductive surface of belt 90 to the dielectric
sheet. A non-conductive rubber pad 116 is positioned
prior to roller 114. After roller ~4 has translated
one half a revolution beyond the end of stationary
platen lOÇ, the entire electrostatic latent image is
effectively transferred to dielectric sheet 112. At
this point, the dielectric sheet moves through the
development station and fusing stations previously
5~V
discussed with regard to Figure 2. ~he dielectric
sheet, with the powder image permanently af~ixed there-
to, is then advanced to a catch tray for subsequent
removal from the printing machine by the operator.
One skilled in the art will appreciate that
many other techniques may be employed in conjunction
with the embodiment shown in Figure 3. For example,
the photoconductive member itself may be the copy sheet
~ith successive portions thereof being cut to size after
development and fusing rather than being advanced about
the take-up spool. Alternatively, the imaye portions
of the photoconductive member may be transferred directly
- to a copy sheet forming a visible image of the original
document. In these latter configurations, each portion
of the photoconductive member is used over rather several
thousand times prior to being replenished.
In recapitulation, it is evident that the repro-
ducing machine of the present invention employs a sta-
tionary photoconductive member and a stationary original
document. A dielectric sheet moves into contact with
the photoconductive member so that the electrostatic
latent image recorded thereon may be transferred there-
to. The processing stations associated with the photo-
conductive member translate relative thereto. A sys-
tem of this type readily lends itself for usage in desktype low cost reproducing machines~
It is, therefore, evident that there has been
provided in accordance with the present invention a
reproducing machine that fully satisfies the aims and
advantages hereinbefore set forth. While this invention
has been described in conjunction with the various
specific embodiments thereof, it will be evident that
many alternatives, modifications and variations will
be apparent to those skilled in ~he art. Accordingly,
it is intended to embrace all such alternatiYes, modi-
fications and variations that fall within the spirit
5~3
-- 16 --
and broad scope of ~.he appended claims.
