Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
2002-12-23
2004-08-17
Ngo, Hoang (Department: 2852)
Electrophotography
Image formation
Photoconductive member
Reexamination Certificate
active
06778796
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a driving mechanism for use in an image forming apparatus for driving a photosensitive member and a rotary member provided in the vicinity of the photosensitive member.
2. Description of the Related Art
Heretofore, known is a driving mechanism
200
for use in an image forming apparatus, as shown in FIG.
7
. Such a conventional driving mechanism
200
drives, by means of a drum driving motor, a photosensitive drum
4
and rotary members provided in the vicinity of the photosensitive drum
4
, such as a cleaning roller
160
for removing toner residuals from the surface of the photosensitive drum
4
and a transfer roller
11
for transferring a toner image formed on the drum surface to a copy sheet. The drum driving motor is interconnected with a rear end part
41
a
′ of the rotary shaft
41
′ via a driving joint
50
′ connected to the drum motor. Thus, the driving force of the drum motor (not shown) is transmitted to the photosensitive drum
4
by means of a rotary shaft
41
′ extending through the photosensitive drum
4
, with the rotary shaft
41
′ rotating with the driving joint
50
′. The rear end
41
a
′ of the rotary shaft
41
′ is a part of the rotary shaft
41
′ provided at the rear side of the image forming apparatus and has a projection
41
c
′ extending radially outwardly. The driving joint
50
′ is coupled to the rotary shaft
41
′ with the driving joint
50
′ covering the rear end part
41
a
′ including the projection
41
c′.
The driving force of the drum motor is transmitted from the photosensitive drum
4
to the cleaning roller
160
and to the transfer roller
11
by means of a drum gear
43
provided at an axial end of the photosensitive drum
4
and meshing with a cleaning roller gear
161
provided at an axial end of the cleaning roller
160
as well as with a transfer roller gear
111
provided at an axial end of the transfer roller
11
, thereby rotating the cleaning roller
160
and the transfer roller
11
along with the photosensitive drum
4
. The drum gear
43
, the cleaning roller gear
161
, and the transfer roller gear
111
are located on the front side of the image forming apparatus and respectively co-rotatably coupled with or attached to the photosensitive drum
4
and the rollers
11
and
16
. Furthermore, the rotary shaft
41
′ is co-rotatably coupled with the photosensitive drum
4
with a front end part
41
b
′ of the rotary shaft
41
′ being fitted in a hole formed in the axially front end part of the photosensitive drum
4
. The front end part
41
b
′ has a generally D-shape in cross section or its equivalent and is at the axially front end thereof, the hole has a cross-sectional shape to match with the cross-sectional shape of the front end part
41
b′.
The rotary shaft
41
′ may be inserted into a hollow portion of the photosensitive drum
4
with the front end part
41
b
′ of the rotary shaft
41
′ being inserted to the hollow portion from the rear side of the image forming apparatus (from the left side in FIG.
7
). When the rotary shaft
41
′ is fully inserted, its front end
41
b
project out of the photosensitive drum
4
, with the rear end
41
a
′ having the projection
41
c
′ being located at the rear side to oppose the driving joint
50
′. The rotary shaft
41
′ and the photosensitive drum
4
are co-rotatably coupled with each other at the front side of the image forming apparatus where the drum gear
43
is in mesh with the cleaning roller gear
161
and the transfer roller gear
111
.
Since the rotary shaft
41
′ and the photosensitive drum
4
are coupled with each other on the front side of the image forming apparatus at a portion of the front end part
41
b
′, the driving force is transmitted through substantially the entire length of the rotary shaft
41
′ from the rear end part
41
a
′ of the rotary shaft
41
′ (rear side of the image forming apparatus) at which the rotary shaft
41
′ is jointed to the driving joint
50
′, to the front end part
41
b
′ of the rotary shaft
41
′ (front side of the image forming apparatus) at which the rotary shaft
41
′ is jointed to the photosensitive drum
4
. Then, the driving force of the drum motor is transmitted to the cleaning roller
160
and the transfer roller
11
.
Thus, before the driving force of the drum motor is transmitted to the transfer roller
11
and the cleaning roller
160
, the driving force is required to be transmitted from the one axial end of the photosensitive drum to the other axial end thereof where a load is applied. Accordingly, it is highly likely that torsional stress may be caused in the rotary shaft
41
′ due to a torque necessary for the rotary shaft
41
′ to rotate the photosensitive drum
4
, the cleaning roller gear
161
and the transfer roller gear
111
, during the transmission of the driving force to the cleaning roller gear
161
and the transfer roller gear
111
. As a result, the rotational speed of the photosensitive drum
4
may fluctuate.
SUMMARY OF THE INVENTION
In view of the above, it is an object of this invention to provide a driving mechanism for use in an image forming apparatus which operates stably.
It is another object of the present invention to provide a driving mechanism which drives a photosensitive drum of an image forming apparatus without fluctuation of rotating speed.
It is still another object of the present invention to provide a driving mechanism which is free from the torsional stress in the driving mechanism.
It is further object of the present invention to provide a driving device for stably driving a photosensitive drum and its related one or more rollers of an image forming apparatus.
It is still further object of the present invention to provide an image forming apparatus including a fixture attaining one or more of the objects as mentioned above.
According to an aspect of this invention, a driving mechanism for use in an image forming apparatus drives a photosensitive member of a substantially cylindrical shape and a rotary member provided in the vicinity of the photosensitive member, the driving member is to be interconnected with a driving motor to be driven thereby. The driving mechanism comprises a rotary shaft extending through the photosensitive member in a longitudinal direction of the photosensitive member and protruding from the photosensitive member at its opposite ends, the rotary shaft being journaled at its axially opposite ends by bearings, and being co-rotatably coupled with the photosensitive member at one of the axially opposite ends thereof, the rotary shaft having a mass larger than that of the photosensitive member; a driving force transmission member which is jointed to the rotary shaft protruding from the photosensitive member at the one of the axial opposite ends, to transmit a driving force of the driving motor to the rotary shaft; a photosensitive member gear provided at the one of the axial opposite ends of the photosensitive member to co-rotate with the photosensitive member; and a rotary member gear provided at the one of the axial opposite ends of the rotary member, the rotary member gear being in mesh with the photosensitive member gear to be driven thereby.
In the above arrangement, the photosensitive member and the rotary shaft are coupled with each other at the side where the photosensitive member gear is in mesh with the rotary member gear and at the lateral side part of the axial end part of the rotary shaft where the rotary shaft is coupled to the photosensitive drum to allow the rotating force of the drum motor to be transmitted via the rotating force transmission member to the photosensitive member. This arrangement shortens a transmission route for the rotating force to be transmitted from the photosensitive member to the rotary member, and thus makes t
Maeshima Masanobu
Matayoshi Akira
Nimura Eiji
Tanaka Nariaki
Tomimori Koshiro
Jordan and Hamburg LLP
Kyocera Mita Corporation
Ngo Hoang
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