Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2002-05-14
2003-09-30
Lee, Susan S.Y. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S162000, C399S165000, C198S313000
Reexamination Certificate
active
06628909
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a method of mounting and aligning an endless belt on associated rollers in a machine. More particularly, the present invention relates to a method and device for facilitating installation of an endless belt, such as a photoconductive belt, into an electrostatographic printing machine.
BACKGROUND OF THE INVENTION
A typical electrostatographic printing machine
10
is diagrammatically illustrated by way of example in FIG.
1
. Printing machine
10
includes a photoconductive member
10
in form of an endless photoconductive belt
12
having a photoconductive surface
14
. The photoconductive belt is mounted on a plurality of guide rollers
16
and backer bars
18
. At least one of the rollers
16
is driven for rotating the belt in the direction of arrow
20
through a plurality of generally conventional electrostatographic printing modules. First, a charging module
22
charges the photoconductive surface
14
of the belt
12
to a substantially uniform potential. An exposing module
24
then exposes the charged photoconductive surface to a light image of an original document being reproduced. Exposure of the charged photoconductive surface
14
selectively dissipates the charge in the irradiated areas of the photoconductive surface. As a result, an electrostatic latent image corresponding to the image of the original document is formed on the photoconductive surface
14
. After the electrostatic latent image is recorded on the photoconductive surface, a developing module
26
develops a latent toner image on the photoconductive surface by bringing a developer material into contact with the photoconductive surface. In typical bi-component developer systems, the developer material is composed of toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image to form a developed toner image on the photoconductive member. The toner image is then transferred from the surface of the photoconductive member
10
to a copy substrate or print sheet
30
, such as a sheet of paper, by a transfer module
28
. Thereafter, heat or some other known treatment is applied to the toner image on the print sheet by a fuser
32
, thereby permanently affixing the toner image to the print sheet. Residual toner is removed from the photoconductive member by a cleaner
34
.
In order to generate multi-color prints, there may be a group of process modules
22
,
24
,
26
through
22
-C,
24
-C,
26
-C for each of a plurality of colors. For example, there may be a group of modules for each of cyan
22
,
24
,
24
,
26
, yellow
22
-A,
24
-A,
26
-A, magenta
22
-B,
24
-B,
26
-B and black
22
-C,
24
-C,
26
-C. There may also be one or more additional sets of modules
22
-D,
24
-D,
26
-D for one or more custom colors. One method of generating multicolor prints is to arrange all of the color modules around a single photoreceptor belt
12
as illustrated in FIG.
1
. The full color image may be formed by exposing and developing all of the color toner images, one on top of each other, during a single rotation of the photoreceptor belt. The full color toner image may then be transferred from the photoreceptor belt directly to a print sheet.
An alternative method of generating full color prints is to expose and develop each individual color image on the photoreceptor belt
12
separately, and transfer the single color toner image to an intermediate transfer belt (not shown) before exposing and developing the next color toner image. This is repeated for each color, thereby building up a full color toner image on the intermediate transfer surface. The full color toner image is then transferred from the intermediate transfer surface to the print sheet. The intermediate transfer surface may be formed on an intermediate transfer belt, roll, drum or other suitable structure.
The electrostatographic printing processes described above are well known and are commonly used for light lens and digital reproduction of an original document. In each of the above described methods, four or more sets of discharging
22
, exposing,
24
and developing
26
modules are spaced around the photoreceptor belt
12
in order to generate a full color image. The photoreceptor belt must be relatively large in order to accommodate all of the reprographic modules around its periphery. Such a photoreceptor belt may, for example, have a circumference of about 2.8 meters. The ability of the photoreceptor belt
10
to obtain and retain the desired charges degrades over time. As a result, the photoreceptor belt requires regular replacement to maintain optimal performance of the machine. The relatively large photoreceptor belt required for the full color machines described above is cumbersome to handle due to its size and weight.
Referring now to
FIGS. 2 and 3
, in existing machines the guide rollers
16
and backer bars
18
may be mounted on a photoreceptor sub-frame
40
. The sub-frame may include an outboard plate
42
and an inboard plate
44
, with the guide rollers and backer bars being mounted for rotation between the plates
42
and
44
. The sub-frame may be mounted to the machine frame (not shown) on slides (not shown). With this construction, the sub-frame may be undocked form the machine frame and slid partway out of the machine frame, in order to facilitate access thereto for maintenance, such as photoreceptor belt replacement. Some of the rollers and/or guide plates may be moved into a retracted position (not shown), i.e. radially inward relative to the belt (not shown in FIG.
2
), such that the overall peripheral circumference defined by the guide rollers and backer bars is reduced. This provides some slack in the photoreceptor belt
12
during belt installation and removal of the belt, thereby facilitating installation and removal of the belt.
Once installed, the photoreceptor belt
12
is maintained in proper alignment in an optimum position on the guide rollers
16
by a steering mechanism. The steering mechanism typically includes a belt edge sensor
46
for determining the location of the inboard edge
52
of the photoreceptor belt in a known manner. One known type of suitable sensor emits an output voltage that varies depending on the detected location of the inboard edge
52
of the photoreceptor belt. The further inboard the edge of the belt moves, the higher the magnitude of the output voltage emitted by the belt edge sensor becomes.
When the output voltage of the sensor deviates from an acceptable range of voltages, then the steering mechanism steers the belt back toward its optimum position, until the belt edge sensor output voltage is back within the acceptable range. In order to steer the belt
12
in the inboard or outboard direction as required to move the belt back within an acceptable range of the optimum position, one of the rollers, a steering roller
48
, is pivoted by a stepper motor
50
, or other suitable means (not shown).
When installing a photoreceptor belt
12
in existing machines, the operator must first manually place the inboard edge
52
of the photoreceptor belt
12
over the guide rollers
16
and backer bars
18
, as shown in FIG.
3
. Care must be taken to clear the edges of the rollers, backer bars and other components on or near the outboard plate
42
of the photoreceptor sub-frame
40
, in order to avoid damaging the photoreceptor belt
12
. Once these components are cleared, the photoreceptor belt is slid further onto the rollers and backer bars, until the inboard edge
52
of the photoreceptor belt contacts and begins to activate the belt edge sensor
46
. The operator now checks the output voltage of the belt edge sensor to determine if the photoreceptor belt is within the effective range of the steering mechanism. The steering mechanism's effective range of operation may be, for example, +/−1 mm of the ideal position for the photoreceptor belt. The operator typically checks to see if the belt is within this range by attaching a
Hancock Joseph D.
Lopez Carlos A.
Monahan Michael B.
Gleitz Ryan
Lee Susan S.Y.
Xerox Corporation
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