Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
2001-08-21
2002-10-01
Lee, Susan S. Y. (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
C399S350000, C399S351000, C399S360000
Reexamination Certificate
active
06459866
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cleaning device and an image forming apparatus having the cleaning device.
2. Description of the Related Art
In the image forming with use of the image forming apparatus such as a facsimile, a printer, or a copying machine, which employs electrophotography, steps of charging and exposing are performed by the rotation of a photosensitive drum, a developing step is then performed to form a toner image on a circumference of the photosensitive drum, subsequently, a transfer step follows thereto to transfer the toner image onto a record paper, and a discharging step is performed thereafter to discharge the circumference of the photosensitive drum.
In the image forming cycle, the residual toner left on the circumference of the photosensitive drum after the transfer step is performed is unnecessary for the discharging step and the charging step performed after the transfer step, and thus the image forming apparatus is provided with a cleaning device for performing a cleaning step between the transfer step and the discharging step, during which the residual toner on the circumference of the photosensitive drum is removed and collected.
As shown in
FIG. 11
, the cleaning device
7
comprises a device case
21
having a toner collecting space
22
opened to the circumference of the photosensitive drum
2
; a blade holder
23
swingably supported by the device case
21
in the directions in which the blade holder approaches and leaves from the photosensitive drum
2
and extending to the opening of the toner collecting space
22
; a blade
25
attached to the blade holder to cover together with the blade holder the opening of the toner collecting space
22
and to contact with the circumference of the photosensitive drum
2
when the blade holder swings in the direction approaching the photosensitive drum
2
, so that the blade rakes up the toner left on the circumference of the photosensitive drum
2
toward the inside of the toner collecting space
22
; and an elastic member
26
for applying a force to the blade holder in the direction in which the blade holder approaches the photosensitive drum so that the blade urgingly contacts onto the circumference of the photosensitive drum
2
.
In order to prevent the leak of the toner collected in the toner collecting space
22
formed in the device case
21
, the cleaning device is formed such that the opening of the toner collecting space
22
facing the circumference of the photosensitive drum
2
is covered with the blade holder
23
, the blade
25
, and the photosensitive drum
2
, and the space between the outer face of the wall forming the toner collecting space
22
and the blade holder
23
is closed by an elastic seal member
28
attached to the wall of the toner collecting space
22
or the blade holder
23
to urgingly contact with the blade holder
23
or the wall of the toner collecting space
22
.
The conventional elastic seal member
28
is formed such that contact faces
28
m
and
28
n
urgingly contacting with the blade holder
23
or the wall of the toner collecting space
22
are formed in planes, and contact faces
23
m
and
23
n
of the blade holder
23
and the wall of the toner collecting space
22
with which the contact faces of the elastic seal member
28
urgingly contact are also formed in planes so that the elastic seal member
28
can contact with the blade holder
23
or the wall of the toner collecting space
22
on a plane. In order to prevent the leak of the toner from the contacting face of the elastic seal member
28
and the blade holder
23
or the wall of the toner collecting space
22
, the cleaning device
7
is installed in the body of the image forming apparatus
1
so that the blade holder
23
and the wall of the toner collecting space
22
urgingly contact with the elastic seal member
28
with a necessary pressure.
However, according to the above-mentioned structure of the conventional cleaning device, the entire plane contact faces
28
m
and
28
n
of the elastic seal member
28
urgingly contact with the plane contact face
23
m
or
23
n
of the blade holder
23
or the wall of the toner collecting space
22
in order to prevent the leak of the toner. With such a structure, when the cleaning device
7
is installed in the body of the image forming apparatus
1
, the blade holder
23
and the blade
25
will shift from the predetermined position toward the photosensitive drum
2
(in the direction leaving from the elastic seal member). In addition, the elasticity of the elastic seal member
28
will decrease due to the yearly deterioration to shrink the elastic seal member. In accordance with the shrink of the elastic seal member, the contact face shifts backward from the desired contact position, which makes difficult to surely make contact the contact faces of the elastic seal member
28
and the blade holder
23
or the wall of the toner collecting space
22
, with the result that the sealing performance of the contact faces will be deteriorated to leak the toner from the contacting section.
In order to solve the uncertainness of the contact, the contact pressure applied by the blade holder
23
or the wall of the toner collecting space
22
to the elastic seal member
28
is proposed to be increased. In this case, however, the elastic seal member
28
is strongly urged and compressed to generate a strong reaction force against the compression. The reaction force acts on the blade holder
23
to increase the pressure with which the blade
25
contacts with the circumference of the photosensitive drum
2
. If the blade
25
contacts the circumference of the photosensitive drum
2
with more pressure than the necessary one, some problems such as the damage of the circumference of the photosensitive drum
2
may occur.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a cleaning device having improved sealing performance on contact faces of the elastic seal member and the blade holder or the wall of the toner collecting space.
The other object of the present invention is to provide an image forming apparatus having the cleaning device mentioned above.
According to the first embodiment of the present invention, a cleaning device can be provided, which comprises a device case having a toner collecting space opened to a surface of a photosensitive drum; a blade holder swingably supported by the device case in directions in which the blade holder approaches and leaves from the photosensitive drum and extending to the opening of the toner collecting space; a blade attached to the blade holder in order to rake up toner left on the surface of the photosensitive drum toward inside of the toner collecting space; an urging member for applying a force to the blade holder in a direction in which the blade holder approaches the photosensitive drum so that the blade urgingly contacts onto the surface of the photosensitive drum; an elastic seal member attached to one of a wall forming the toner collecting space and the blade holder, between an outer face of the wall forming the toner collecting space and the blade holder facing the wall; and a protrusion attached to one of the blade holder and the wall forming the toner collecting space in order to prevent toner raked by the blade from leaking through a space between the blade holder and the wall of the toner collecting space.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 4323306 (1982-04-01), Ito et al.
patent: 4501620 (1985-02-01), Oda
patent: 4982240 (1991-01-01), Nakano
patent: 5175591 (1992-12-01), Dunn et al.
patent: 5543906 (1996-08-01), Kanda
patent: 6055404 (2000-04-01), Yamazaki et al.
patent:
Frishauf Holtz Goodman & Chick P.C.
Lee Susan S. Y.
Toshiba Tec Kabushiki Kaisha
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