Note: Descriptions are shown in the official language in which they were submitted.
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PATENT APPLICATION
Attorney Docket No. D/93534
PRINTING MACHINE ARCHITECTURE
This invention relates to a printing machine architecture, and
more particularly concerns a vertically oriented photoconductive belt in
which transfer of the toner image to a receiving member occurs at the
uppermost portion of the photoconductive belt, and a plurality of
developer units are located on one side of the photoconductive belt with
the other side being devoid of developer units.
A typical electrophotographic printing machine employs a
photoconductive member that is charged to a substantially uniform
potential so as to sensitize the surface thereof. The charged portion of the
photoconductive member is exposed to a light image of an original
document being reproduced. Exposure of the charged photoconductive
member selectively dissipates the charge thereon in the irradiated areas to
record an electrostatic latent image on the photoconductive member
corresponding to the informational areas contained within the original
document. After the electrostatic latent image is recorded on the
photoconductive member, the latent image is developed by bringing a
developer material into contact therewith. Generally, the electrostatic
latent image is developed with dry developer material comprising carver
granules having toner particles adhering triboelectrically thereto
However, a liquid developer material may be used as well. The toner
particles are attracted to the latent image forming a visible powder image
on the photoconductive surface. After the electrostatic latent image ~s
developed with the toner particles, the toner powder image is transferred
to a sheet. Thereafter, the toner image is heated .to permanently fuse it to
the sheet.
It is highly desirable to use an electrophotographic printing
machine of this type to produce color prints. In order to produce a color
print, it is frequently necessary to form yellow magenta and cyan colo~
separations. One skilled in the art will appreciate that the black separation
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can be made either first or last with respect to the other color separations.
In this way, a permanent color print is formed. It is highly desirable to be
capable of utilizing a common architecture for both monocolor and
multicolor printing. In order to minimize the size of the printing machine,
not only must the various parts of the printer be reduced in size, but the
orientation of the photoconductive belt and transfer station must be
optimized. When optimizing the size of the printing machine, it is
necessary to consider registration of images for multicolor printing. Thus,
the placement of the development stations with respect to the
photoconductive belt effects registration of each developed image relative
to one another. Various types of monocolor and multicolor printing
machines have heretofore been employed. The following disclosure
appears to be relevant:
U.S 4,757,471
Patentee: Fukae et al.
Issued: July 12,1988
U.S. 5,313,259
Patentee: Smith
Issued: May 17,1994
US-A-4,757,471 disclosed an electrographic printer having a
vertically oriented photocondudive belt. A copy sheet travels along a
substantially planar path with the photoconductive belt being located
below the planar path. The copy sheet contacts the photocondudive belt
at the transfer zone. A transfer unit is located at the top of the belt path
to
attract toner from the belt to the sheet passing through the transfer zone.
U.S. Patent 5,313,259 discloses a multicolor electrophotographic
printing machine in which a photoconductive belt is vertically oriented. The
printing machine includes four groups of stations for printing in cyan,
magenta, yellow and black. Each station includes a charge corona generator,
a raster output scanning
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laser assembly, and a developer unit. In the architecture depicted in this
application, three stations are positioned on one side of the photoconductive
belt with a fourth station disposed on the other side of thereof. Successive
different color toner powder images are formed in superimposed registration
with one another on the photoconductive belt and transferred to a copy sheet
simultaneously. Transfer occurs at the lowermost portion of the
photoconductive belt.
In accordance with one aspect of the features of the present
invention, there is provided an electrophotographic printing machine having a
common architecture for black printing machine architecture and for multi-
color printing architecture, including:
a moveable photoconductive belt having minor axis and a major
axis with the major axis being oriented substantially vertically, and the
minor
axis being oriented substantially horizontally;
a developer station comprising a black developer unit with the
black printing machine architecture being devoid of a non-black developer
unit, and a black developer unit and a non-black developer unit for the multi-
color printing machine architecture, said developer station being positioned
on
one side of said photoconductive belt adjacent a surface thereof substantially
perpendicular to the minor axis for developing latent images recorded on the
surface of said photoconductive belt with the surface of said photoconductive
belt opposed from the one side and spaced therefrom and substantially
perpendicular to the minor axis being devoid of developer units for the black
and multi-color printing machine architecture, said black developer unit being
positioned before said non-black developer unit in a direction of movement of
said photoconductive belt;
a transfer station positioned adjacent the uppermost surface of
said photoconductive belt substantially perpendicular to the major axis, for
transferring a developed image from the surface to a final sheet of support
material; and
means for fusing the developed image transferred from the
surface to the final sheet of support material.
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Other aspects of the present invention will become apparent as
the following dexription proceeds and upon reference to the drawings, in
which
Figure 1 is a schematic, elevational view showing a monocolor
printing machine architecture;
Figure 2 is a schematic elevational view showing a multipass,
multicolor printing machine architecture; and
Figure 3 is a xhematic elevational view showing a single pass,
multicolor printing machine architecture.
While the present invention will hereinafter be described in
connection with a preferred embodiment, it will be understood that it is
not intended to limit the invention to that embodiment. On the contrary ,
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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 features of the present
invention, reference is made to the drawings. In the drawings, like
reference numerals have been used throughout to designate identical
elements.
Referring initially to Figure 1, there is shown a monocolor
electrophotographic printing machine architecture. The printing machine
employs a belt 10 having a photoconductive surface deposited on a
conductive substrate. The photoconductive surface comprises an anti-curl
layer, a supporting substrate layer and an electrophotographic imaging
single layer or multiple layers. The imaging layers may contain
homogeneous, hetrogeneous, inorganic or organic compositions.
Preferably, finely divided particles of a photoconductive inorganic
compound are dispersed in an electrically insulating organic resin binder.
The substrate layer may be made from any suitable conductive material
such as Mylar. Another well known conductive material that can be used in
the substrate layer is aluminum. Belt 10 advances successive portions of the
photoconductive surface sequentially through the various processing
stations disposed about the path of movement thereof. A plurality of
rollers or bars 12 provide support for belt 10. These rollers are spaced
apart.
Belt 10 advances in the direction of arrow 14. One of these rollers is
rotatably driven by a suitable motor and drive (not shown) so as to rotate
and advance belt 10 in the direction of arrow 14.
Initially, belt 10 passes through a charging station. At the
charging, a corona generating device 16 charges the photoconductive
surface of belt 10 to a relatively high, substantially uniform potential.
After the photoconductive surface of~belt 10 is charged, the
charged portion thereof is advanced to an exposure station. At the
exposure station, an imaging beam 18, generated by a raster output
scanner (ROS) 20 illuminates the charged portion of the photoconductivc
surface. ROS 20 employs a laser with rotating polygon mirror blocks to
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create the electrostatic latent image on the photoconductive surface of belt
10. This electrostatic latent image is developed by developer unit 22.
Developer unit is a magnetic brush developer unit which
deposits black toner particles on the electrostatic latent image. In this way,
black toner develops the latent image. After the toner image has been
developed on the photoconductive surface of belt 10 with black toner
particles, belt 10 continues to advance in the direction of arrow 14 to
transfer station 24.
At transfer station 24, a sheet of support material is advanced
from a stack 26 by sheet feeders 28 thereto. Alternatively, the support
material may be advanced from stack 30 or stack 32. In either case, the
sheet of support material is advanced to transfer station 24 in registration
with the toner image on belt 10. A corona generating device sprays ions
onto the backside of the sheet of support material. This attracts the
developed image from the photoconductive surface of belt 10 to the sheet
of support material. A vacuum transport 34 moves the sheet of support
material in the direction of arrow 36 to fusing station 38. While
transferring the developed image to a receiving medium has been
described wherein the receiving medium is a sheet of support material, e.g.
paper, one skilled in the art will appreciate that the developed image may
be transferred to an intermediate member, such as a belt or drum, and
then, subsequently transferred from the intermediate member to the sheet
of paper and fused thereto.
Fusing station 38 includes a heated fuser roller 40 and backup or
pressure roller 42. The backup roller is resiliently urged into engagement
with the fuser roll to form a nip through which the sheet passes. In the
fusing operation, the toner particles coalesce and bond to the sheet in
image configuration forming a monocolor image thereon. After fusing,
the finished sheet is discharged to finishing station 44. At finishing station
44, sheets are compiled and stapled and/or adhesive bound to one another.
After the finishing operation is completed, the finished set of sheets is
advanced to a catch tray 46 for removal therefrom by the operator.
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Invariably, after the sheet is separated from the
photoconductive surface of belt 10 at the transfer station, some residual
particles remain adhering thereto. These residual particles are removed
from the photoconductive surface at cleaning station 48. Cleaning station
48 includes a pair of rotatably mounted fibrous brushes or a rotating brush
and a blade which are electrically biased to attract particles from the
photoconductive surface. The brushes are in contact with the
photoconductive surface. Subsequent to cleaning, a discharge lamp (not
shown) floods the photoconductive surface with light to dissipate any
residual or electrostatic charge remaining thereon prior to the charging
thereof for the successive imaging cycle.
Referring now to Figure 2, there is shown a multipass multicolor
printing machine architecture. As shown thereat, photoconductive belt 10
is entrained about a plurality of rollers 12. One of the rollers is coupled to
a
suitable motor (not shown) so as to be rotatably driven thereby. In this
way, photoconductive belt 10 advances in the direction of arrow 14.
Initially, belt 10 passes through a charging station. At the
charging station, a corona generating device 16 charges the
photoconductive surface of belt 10 to a relatively high, substantially
uniform potential.
After the photoconductive surface of belt 10 is charged, the
charged portion thereof is advanced to an exposure station. At the
exposure station, an imaging beam 18 generated by the raster output
scanner 20 exposes the charged portion of the photoconductive surface to
record a color separated electrostatic latent image thereon. This color
separated electrostatic latent image is developed by developer unit 22
Developer unit 22 develops the electrostatic latent image recorded on
photoconductive belt 10 with black toner particles.
After the black toner image has been developed on the
photoconductive surface of belt 10, belt 10 continues to advance in the
direction of arrow 14. The developed image on belt 10 passes beneath
transfer station 24 and cleaning station 48. Both of these stations are
nonoperative, i.e. the cleaning brushes are spaced from the
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photoconductive belt. Thereafter, the developed image returns to the
charging station 16 where the photoconductive belt having the first
developed image thereon is recharged to a relatively high, substantially
uniform potential. Thereafter, a different imaging beam 18 from ROS 20
selectively dissipates the charge to record another partial electrostatic
latent image on the photoconductive surface of belt 10 corresponding to
regions to be developed with yellow toner particles. This partial
electrostatic latent image is now advanced to the next successive developer
unit SO which deposits yellow toner particles thereon.
After the electrostatic latent image has been developed with
yellow toner, belt 10 continues to advance in the direction of arrow 14
through transfer station 24 and cleaning station 48, both of which are
nonoperative, to charging station 16. At charging station 16, a corona
generating device charges the photoconductive surface of belt 10 to a
relatively high, substantially uniform potential. Thereafter, another
imaging beam 18 from ROS 20 selectively discharges the charge on the
photoconductive surface to record a partial electrostatic latent image for
development with magenta toner particles. After the latent image is
recorded on the photoconductive surface, belt 36 advances the latent
image to the magenta developer unit 52. The magenta developer unit
deposits magenta toner particles in registration with the yellow and black
toner powder images previously formed thereon to form a magenta toner
powder image in superimposed registration therewith.
After the magenta toner image has been formed on the
photoconductive surface of belt 10, belt 10 advances in the direction of
arrow 14 through transfer station 24 and cleaning station 48 to charging
nation 16. At this time, both the transfer station 24 and cleaning station 48
are nonoperative.
At charging station 16, a corona generator recharges the
photoconductive surface to a relatively high, substantially uniform
potential. Thereafter, another imaging beam 18 from ROS 20 selectively
discharges those portions of the charged photoconductive surface which
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are to be developed with cyan toner. The latent image to be developed
with cyan toner is advanced to the cyan developer unit 54.
At the cyan developer unit, cyan toner particles are deposited on
the latent image to produce a cyan toner powder image. The cyan toner
powder image is superimposed, at least partially, on those toner powder
images previously developed on photoconductive surface of belt 10.
After the cyan toner powder image is developed on the
photoconductive surface of belt 10, belt 10 advances to transfer station 24.
At the transfer station, a sheet of support material, i.e. paper, is
advanced from a stack 26 by sheet feeder 28. The sheet advances and is
guided to the transfer station. A corona generating device located at the
transfer station sprays ions onto the backside of the paper. This attracts the
developed image from the photoconductive surface of belt 10 to the sheet
of paper. A vacuum transport moves the sheet of paper in the direction of
arrow 36 to fusing station 38.
While transferring the multicolor developed image to a sheet of
paper has been described, one skilled in the art will appreciate that the
multicolor developed image may be transferred to an intermediate
member, such as a belt or drum and then, subsequently, transferred to the
sheet and fused thereto.
The fusing station 38 includes a heated fuser roll 40 and a
backup roll 42. The backup roll is resiliently urged into engagement with
the fuser roll to form a nip through which the sheet of paper passes. In the
fusing operation, the toner particles coalesce with one another and bond
to the sheet in image configuration forming a multicolor image thereon.
After fusing, the finished sheet is discharged to a finishing station 44. At
the finishing station, a plurality of sheets are bound together either by
stapling and/or by applying an adhesive thereto to form a set of sheets.
This set of sheets is then advanced to a catch tray 46 for subsequent
removal therefrom by the machine operator.
A multiplicity of finishing devices, such as sorter, stapler, etc.,
may be attached to the printing machine.
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The cleaning brushes are brought into contact with the
photoconductive belt. In this way, residual particles adhering to the
photoconductive surface of belt 10 are cleaned therefrom, after the
transfer of the multicolor toner image therefrom by cleaning station 48.
Referring now to Figure 3, there is shown a single pass
multicolor printing machine. This printing machine employs a
photoconductive belt 10 supported by a plurality of hollers or bars 12.
Photoconductive belt 10 is arranged in a vertical orientation. Belt 10
advances in the direction of arrow 14 to move successive portions of the
photoconductive surface sequentially beneath the various processing
stations disposed about the path of movement thereof.
Initially, belt 10 passes through charging station 16. At the
charging station, a corona generating device charges the photoconductive
surface of belt 10 to a relatively high, substantially uniform potential.
After
the photoconductive surface of belt 10 is charged, the charged portion
thereof is advanced to an exposure station. At the exposure station, an
imaging beam 18 generated by ROS 20 creates a color separated
electrostatic latent image on the photoconductive surface of belt 10. This
color separated electrostatic latent image is developed by developer unit
22.
The developer unit 22 deposits black toner particles on the
electrostatic latent image. In this way, a black toner powder image is
formed on the photoconductive surface of belt 10.
After the black toner image has been developed on the
photoconductive surface of belt 10, belt 10 continues to advance in the
direction of arrow 12 to a recharge station where corona generating device
56 recharges the photoconductive surface to a relatively high, substantially
uniform potential. Thereafter, a different imaging beam 18 from ROS 20
selectively dissipates the charge to record another partial electrostatic
latent image on the photoconductive surface of belt 10 corresponding to
the regions to be developed with yellow toner particles. This partial
electrostatic latent image is now advanced to the next successive developer
unit 50.
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Developer unit SO deposits yellow toner particles on the
photoconductive surface of belt 10 to form a yellow toner powder image
thereon.
After the electrostatic latent image has been developed with the
yellow toner, belt 10 advances in the direction of arrow 12 to the next
recharged station. At this recharge station, a corona generating device 58
charges the photoconductive surface of belt 10 to a relatively high,
substantially uniform potential. Thereafter, another imaging beam 18
from ROS 20 selectively discharges the charge on the photoconductive
surface to record a partial electrostatic latent image for development with
magenta toner particles. After the latent image is recorded on the
photoconductive surface, belt 10 advances the latent image to the magenta
developer unit 52.
Magenta developer unit 52 deposits magenta toner particles on
the latent image. These toner particles may be partially in superimposed
registration with the previously formed yellow powder image. After the
magenta toner powder image is formed on the photoconductive surface of
belt 10, belt 10 advances to the next recharge station.
At the next recharged station, corona generator 60 recharges
the photoconductive surface of belt 10 to a relatively high, substantially
uniform potential. Thereafter, another imaging beam 18 from ROS 20
selectively discharges those portions of the charged photoconductive
surface which are to be developed with cyan toner particles. The latent
image to be developed with cyan toner particles is advanced to cyan
developer unit 54.
At cyan developer unit 54, cyan toner particles are deposited on
the photoconductive surface of belt 10. These cyan toner particles form a
cyan toner powder image which may be partially or totally in superimposed
registration with the previously formed yellow and magenta toner powder
images. In this way, a multicolor toner powder image is formed on the
photoconductive surface of belt 10.
Thereafter, belt 10 advances the multicolor toner powder image
to the transfer station 24. At transfer station 24, a sheet of support
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material, i.e. paper, is advanced from stack 32 by sheet feeders 28 and
guided to transfer station 24. At transfer station 24, a corona generating
device sprays ions onto the backside of the paper. This attracts the
developed multicolor image from the photoconductive surface of belt 10 to
the sheet of paper. A vacuum transport 34 moves the sheet of paper in the
direction of arrow 36 to fusing station 38.
Fusing station 38 includes a heated fuser roll 40 and backup roll
42. The backup roll is resiliently urged into engagement with the fuser roll
to form a nip through which the sheet of paper passes. In the fusing
operation, the toner particles coalesce with one another and bond to the
sheet in image configuration forming a multicolor image thereon. After
fusing, the finished sheet is discharged to a finishing station 44 where the
sheets are compiled and formed into sets which may be bound to one
another. These sets are then advanced to a catch tray 46 for subsequent
removal therefrom by the printing machine operator.
One skilled in the art will appreciate that while the multicolor
developed image has been disclosed as being transferred to a sheet of
support material, e.g. paper, it may be transferred to an intermediate
member, such as a belt or drum, and then, subsequently transferred and
fused to the sheet of support material. Furthermore, while toner powder
images and toner particles have been disclosed herein, one skilled in the art
will appreciate that a liquid developer material employing toner particles ~n
a liquid carrier may also be used.
Invariably, after the multicolor toner powder image has been
transferred to the sheet of paper, residual toner particles remain adhering
to the photocondudive surface of belt 10. These residual toner particles
are removed therefrom by cleaning station 48.
In each of the printing machine architectures described
hereinbefore, photoconductive belt 10 is arranged in a vertical orientation
The photoconductive belt has a major axis 120 and a minor axis 118. The
major and minor axes are perpendicular to one another. The major axis 110
is substantially parallel to the gravitational vector and arranged in a
substantially vertical orientation. The minor axis 118 is substantially
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perpendicular to the gravitational vector and arranged in a substantially
horizontal direction. In each case, the transfer station is located at the
uppermost portion of the photoconductive surface opposed from the
surface of the belt substantially perpendicular the major axis 120. All of the
developer units are located on one side of the belt adjacent the surface
thereof perpendicular to the minor axis 118 thereof. The other surface of
the photoconductive belt opposed from the side thereof having the
developer units disposed thereat is devoid of developer units. This
arrangement facilitates registration of successive toner images.
Architectures of this type minimize the foot print (area of floor used by
machine) of the printing machine while maximizing productivity thereof.
Furthermore, the sheet path is simplified with transfer occurring at the
uppermost portion of the photoconductive belt.
In recapitulation, it is clear that the present invention is directed
to a vertically oriented photoconductive belt wherein transfer occurs at the
uppermost portion of the photoconductive belt and all of the developer
units are arranged on one side of the photoconductive belt adjacent a
surface thereof.
It is, therefore, apparent that there has been provided in
accordance with the present invention, a printing machine architecture
which fully satisfies the aims and advantages hereinbefore set forth. While
this invention has been described in conjunction with a specific
embodiment thereof, it is evident that many alternatives, modification and
variations will be apparent to those skilled in the art. Accordingly, it is
intended to embrace all such alternatives, modifications and variations that
fall within the spirit and broad scope of the appended claims.
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