Electrophotography – Image formation – Transfer
Reexamination Certificate
2001-12-13
2004-03-30
Lee, Susan S. Y. (Department: 2852)
Electrophotography
Image formation
Transfer
C399S350000
Reexamination Certificate
active
06714755
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a belt stretcher that can be downsized, and a color image formation apparatus incorporating the same, in particular to a so-called tandem color image formation apparatus for transferring toner images formed by a plurality of single-color toner image formers in sequence to a belt or a recording medium held on the belt, thereby forming a color image.
Generally, each toner image former has a photoconductor having a photosensitive layer on the outer peripheral surface, a charger for uniformly charging the outer peripheral surface of the photoconductor, an exposer for selectively exposing the outer peripheral surface charged uniformly by the charger for forming an electrostatic latent image, and a developer for giving toner to the electrostatic latent image formed by the exposer for providing a visible image (toner image).
The known tandem image formation apparatus for forming a color image is of the type wherein a plurality of (for example, four) toner image formers as mentioned above are placed for an intermediate transfer belt and toner images on photoconductors provided by the single-color toner image formers are transferred to the intermediate transfer belt in sequence for superposing the toner images of a plurality of colors (for example, yellow, cyan, magenta, and black) on the intermediate transfer belt, thereby providing a color image on the intermediate transfer belt. Another known tandem image formation apparatus is of the type wherein a recording medium, such as paper, is held on a recording medium holding belt and toner images provided by a plurality of single-color toner image formers are transferred to the recording medium in sequence for superposing the toner images of a plurality of colors on the recording medium, thereby providing a color image on the recording medium.
The tandem color image formation apparatus of each type comprises a meander regulation (meander prevention) mechanism because a color shift occurs if the belt meanders.
An apparatus as shown in
FIG. 10
is a related tandem image formation apparatus for forming a color image (disclosed in Japanese Patent Publication No. 3-191368A).
In this image formation apparatus, a plurality of (in this case, four) single-color toner image formers
101
(A, B, C, and D) are placed for an intermediate transfer belt
100
.
Each single-color toner image former
101
has a photoconductor
102
having a photosensitive layer on the outer peripheral surface, a charger
103
for uniformly charging the outer peripheral surface of the photoconductor
102
, an exposer
104
for selectively exposing the outer peripheral surface charged uniformly by the charger
103
for forming an electrostatic latent image, and a developer
105
for giving toner to the electrostatic latent image formed by the exposer
104
for providing a visible image (toner image).
The toner images on the photoconductors
102
provided by the single-color toner image formers
101
are primarily transferred to the intermediate transfer belt
100
in sequence by corona transfer devices
106
for superposing the toner images of a plurality of colors (for example, yellow, cyan, magenta, and black) in sequence on the intermediate transfer belt
100
, thereby providing a color image on the intermediate transfer belt
100
, and the color image is secondarily transferred from the intermediate transfer belt
100
to a recording medium P by a corona transfer device
110
in a secondary transfer section T
2
.
The recording medium P is supplied one at a time from a paper feeding cassette
107
by a paper feeding belt
108
and passes through gate rollers
109
. In the secondary transfer section T
2
, a color toner image is transferred to the recording medium P. After then, the recording medium P is transported on an attractive transport belt
111
. The color toner image is fixed by a fixing section
112
and the recording medium P is ejected onto a paper ejection tray
114
by ejection rollers
113
.
Each single-color toner image former
101
is provided with a cleaning blade
115
for removing toner remaining on the surface of the photoconductor
102
after the toner image is transferred to the intermediate transfer belt
100
, and the intermediate transfer belt
100
is provided with a cleaning blade
120
for removing toner remaining thereon after the secondary transfer.
The intermediate transfer belt
100
is placed on a drive roller
130
and a driven roller
131
, and a tension roller
132
is placed on a slack side
100
a
of the intermediate transfer belt
100
. A press roller
133
for pressing the intermediate transfer belt
100
against the photoconductor
102
is placed on a tense side
100
b
of the intermediate transfer belt
100
.
The cleaning blade
120
abuts the intermediate transfer belt
100
in a winding part of the intermediate transfer belt
100
around the driven roller
131
. Numeral
116
denotes a sensor for detecting a reference position of the belt.
The cleaning blade
120
acts on circulation of the intermediate transfer belt
100
as resistance. It acts as large resistance particularly when the drive roller
130
is activated (when circulating the belt is started).
In the related image formation apparatus, the cleaning blade
120
abuts the intermediate transfer belt
100
in the winding part of the intermediate transfer belt
100
around the driven roller
131
and thus the resistance of the cleaning blade
120
in the abutment part acts on the intermediate transfer belt
100
as a tensile force between the winding part and the winding part of the belt around the drive roller
130
.
The abutment state of the cleaning blade
120
on the intermediate transfer belt
100
is not always stable because of the friction therebetween and becomes unstable particularly at the initial stage of driving. Therefore, in this stage, the tension acting on the intermediate transfer belt
100
between the drive roller
130
and the cleaning blade
120
also becomes unstable.
Therefore, the expansion and contraction state of the intermediate transfer belt
100
becomes unstable so that a shift between the transfer positions of color toner images onto the intermediate transfer belt
100
easily occurs. Consequently, the quality of a color image is easily degraded.
In this kind of color image formation apparatus, if the intermediate transfer belt meanders, a shift between colors occurs and thus it is desirable that a meander regulation (meander prevention) mechanism should be provided. In the apparatus as described above, the secondary transfer section T
2
is formed in the winding part of the intermediate transfer belt
100
around the driven roller
131
. Thus, it is undesirable that the driven roller
131
is used as a meander regulation roller. Since meander of the intermediate transfer belt is mainly regulated in the process from the winding start position of the intermediate transfer belt around the meander regulation roller to the winding end part, the intermediate transfer belt is easily displaced in the width direction thereof in the winding part and therefore the state of the secondary transfer easily becomes unstable.
Thus, in the apparatus as described above, the tension roller
132
or the press roller
133
needs to be used as a meander regulation roller.
However, in such a configuration, it is impossible to eliminate the tension roller
132
or the press roller
133
contrary to the requirement of simplification or downsizing of the apparatus. In addition, as seen in
FIG. 10
, the winding angle of the intermediate transfer belt
100
around the tension roller
132
, the press roller
133
is small and thus it is hard to provide a sufficient meander regulation effect.
As a belt stretcher having a meander regulation mechanism, a mechanism as shown in
FIG. 11
is known (disclosed in Japanese Patent Publication No. 5-52244A).
In the figure, a belt
3
is placed on a drive roller
1
and a driven roller
2
and circulated in the arrow A direction, with a driving force provided from a drive mo
Lee Susan S. Y.
Seiko Epson Corporation
Sughrue & Mion, PLLC
LandOfFree
Belt stretcher and color image formation apparatus... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Belt stretcher and color image formation apparatus..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Belt stretcher and color image formation apparatus... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3203006