Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2000-07-07
2004-03-09
Beatty, Robert (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S101000
Reexamination Certificate
active
06704528
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus using an electrophotographic process such as a copying machine, a printer, a facsimile telegraph, etc.
2. Related Background Art
For example, the construction of an image forming apparatus using an intermediate transfer member is adopted in an image forming apparatus having a full color or multiplex image forming function in many cases.
In this image forming apparatus, component color toner images corresponding to plural color component images of a full color image or a multiplex image as an object are sequentially formed on a first image bearing member such as an electrophotographic photosensitive member, an electrostatic recording dielectric, etc. by suitable image forming process means. These component color toner images are sequentially superimposed and transferred to the intermediate transfer member as a second image bearing member being generally of a rotary belt type by a primary transfer portion. Thus, a full color image and a multiplex toner image corresponding to the full color image and the multiplex image as an object are synthesized and formed on the intermediate transfer member. The toner image synthesized and formed on this intermediate transfer member is transferred to a transfer material by a secondary transfer portion. This transfer material is guided to a fixing portion and the image is fixed so that a full color image forming object is obtained.
Here, the image forming apparatus adopting an intermediate transfer belt as the second image bearing member (intermediate transfer member) will be explained with reference to FIG.
11
.
FIG. 11
shows the image forming apparatus with an intermediate transfer unit
120
and a cleaner unit
112
as centers, and shows only one of plural image forming portions.
Component color toner images corresponding to plural color component images formed on an image bearing member
101
are sequentially superimposed and transferred by a primary transfer portion T
1
nipped between the image bearing member
101
and a primary transfer opposite roller
102
. Thus, a full color image as an object is formed on an intermediate transfer belt
103
. This full color image on the intermediate transfer belt
103
is collectively transferred to a transfer material P by a secondary transfer portion T
2
formed by a secondary transfer roller
118
and a secondary transfer opposite roller
105
. The full color image is then fixed by an unillustrated fixing portion so that a full color forming object is obtained.
The intermediate transfer unit
120
is composed of the primary transfer opposite roller
102
, the intermediate transfer belt
103
, rollers of three shafts for supporting the intermediate transfer belt
103
, i.e., a drive roller
104
, the secondary transfer opposite roller
105
, and a tension roller
106
as a movable roller. The intermediate transfer unit
120
can be detachably attached to an apparatus main body.
Tensile force of the intermediate transfer belt
103
is constantly maintained by pressurizing a bearing
107
of the swingable tension roller
106
by a compressing spring
108
.
The cleaner unit
112
is arranged around the intermediate transfer belt
103
and cleans toner not transferred in the secondary transfer but left as the residual transfer remaining on the intermediate transfer belt
103
. The cleaner unit
112
has a cleaning blade
111
abutting on the intermediate transfer belt
103
, and a cleaner container
110
for containing the remaining toner removed by the cleaning blade
111
. The cleaning blade
111
is retained by the cleaner container
110
. A backup roller
109
is arranged in an opposite portion of the cleaning blade
111
. The cleaner unit
112
and the backup roller
109
are fixed to the apparatus main body or the intermediate transfer unit
120
.
Japanese Patent Application Laid-open No. 5-289426 discloses a cleaning blade arranged such that the cleaning blade is opposed to a tension roller for tensioning a photosensitive belt. A photosensitive member unit having first and second casing members is disclosed more particularly. A shaft of a drive roller for driving the photosensitive belt and a shaft of an exposure roller for supporting an exposure position of the photosensitive belt are assembled into the first casing member. A charger for charging the photosensitive belt and a cleaning blade for cleaning the photosensitive belt are assembled into the second casing member.
Further, it is also disclosed that a shaft of the tension roller is guided to an elongated hole formed in the first casing member and is also guided to an elongated hole formed in the second casing member.
However, the following problems exist in the above conventional example since the cleaner unit
112
of the intermediate transfer belt
103
is fixed to the main body or the intermediate transfer unit
120
.
(1) The tension roller
106
for maintaining the tensile force of the intermediate transfer belt
103
constant and a roller for controlling the deviation of the belt are movable to make an alignment adjustment. Therefore, the position of a surface of the intermediate transfer belt
103
is also changed in accordance with the positions of the movable rollers. In such a case, the cleaning blade
111
does not abut against the intermediate transfer belt
103
depending on the position of the surface of the intermediate transfer belt
103
, and hence the cleaning blade
111
does not fulfil its role as a cleaner. Further, the backup roller
109
is required in the opposite portion of the cleaning blade
111
so that the number of parts is increased and the construction becomes complicated.
(2) When the cleaner unit
112
is fixed to the intermediate transfer unit
120
and when one of the intermediate transfer belt
103
and the cleaner unit
112
is exchanged by life, etc., both the units must be simultaneously exchanged, which is not economical and efficient.
In the image forming apparatus disclosed in Japanese Patent Application Laid-open No. 5-289426, the tension roller is displaced in two directions and these two directions are not perpendicular to each other at any time. Accordingly, when the tension roller is displaced, abutting positions of the tension roller and a tip of the cleaning blade abutting through the photosensitive belt are changed. Namely, an abutting angle of the cleaning blade on the photosensitive belt and an inroad amount of the cleaning blade tip are changed. Therefore, there is a fear of generation of a cleaning defect in which toner passes through the cleaning blade, etc.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an image forming apparatus for preferably maintaining a contact state of a cleaning member and a belt member and able to prevent the generation of a cleaning defect even when a roller for supporting the belt member is moved.
The other objects of the present invention will become apparent by reading the following detailed explanation.
REFERENCES:
patent: 4924272 (1990-05-01), Hediger et al.
patent: 5258816 (1993-11-01), Haneda et al.
patent: 5708928 (1998-01-01), Fukunaga
patent: 5870650 (1999-02-01), Takahashi et al.
patent: 5907752 (1999-05-01), Kondoh
patent: 6029033 (2000-02-01), Kawasaki
patent: 04060575 (1992-02-01), None
patent: 5-289426 (1993-11-01), None
patent: 10-326068 (1998-12-01), None
patent: 11-002936 (1999-01-01), None
Kawaguchi Hiroshi
Kawamura Hiroshi
LandOfFree
Image forming apparatus having detachable cleaning unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image forming apparatus having detachable cleaning unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image forming apparatus having detachable cleaning unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3217063