Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
2001-07-13
2003-03-25
Beatty, Robert (Department: 2852)
Electrophotography
Image formation
Photoconductive member
Reexamination Certificate
active
06539189
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, a multi-functional image forming apparatus, etc., and more particularly to an image bearing member rotation control device and method for controlling rotations of the image bearing member such as a photoreceptor and an intermediate transfer member used in the image forming apparatus.
2. Discussion of the Background
In an electrophotographic image forming apparatus, after a toner image formed on an image bearing member is transferred to a transfer material such as a transfer sheet and an intermediate transfer member, a cleaning device removes residual toner from the surface of the image bearing member for a next image forming operation.
One type of cleaning device employs a cleaning blade, and a leading edge of the cleaning blade is press-contacted against a surface of an image bearing member to remove toner remaining on the image bearing member.
In such a cleaning device, the friction between the cleaning blade and the image bearing member changes depending on a contact condition therebetween. When the friction between the cleaning blade and the image bearing member is high, resonance noise may occur between the leading edge of the cleaning blade and the image bearing member. Even though the resonance noise does not occur when the image bearing member rotates at a process speed in an image forming operation, the resonance noise is likely to occur when the image bearing member rotates at a low speed immediately before its rotation stops.
The above-described resonance noise produced between the leading edge of the cleaning blade and the image bearing member before the rotation stops of the image bearing member may be referred to as “blade noise” hereinafter.
In a background image forming apparatus employing an image forming process cartridge including a photoreceptor and a cleaning blade, a control material is attached to an inner wall of the photoreceptor to prevent the occurrence of resonance noise between the photoreceptor and the cleaning blade.
In another background image forming apparatus employing an image forming process cartridge including a photoreceptor and a charging roller, the photoreceptor includes a substance having a specific gravity of 0.5 or greater to prevent a vibration caused by elastic deformation of the photoreceptor and the charging roller. As a result of preventing the vibration of the photoreceptor and the charging roller, noise due to the vibration is avoided.
In the above-described both background image forming apparatuses, because the photoreceptor is often replaced based on the number of image forming operations, the total cost of a number of photoreceptors is increased by such a control material or a substance having a specific gravity of 0.5 or greater. In addition, when an image forming apparatus employs a relatively large sized photoreceptor, the size of the control material is required to be increased. Consequently, the cost of the photoreceptor increases.
Further, in the image forming apparatus with the photoreceptor including the substance having a specific gravity of 0.5 or greater, the photoreceptor is always in a braking condition. In such a braking condition, wear of a transmission gear for driving the photoreceptor may be accelerated.
Another background image forming apparatus which prevents the occurrence of blade noise is described referring to FIG.
13
.
FIG. 13
is a view of a relationship between a number of revolutions (rpm) of a photoreceptor and a time until the rotation of the photoreceptor stops. As illustrated in
FIG. 13
, in a period between a number of revolutions “b” (rpm) and a number of revolutions “zero”, a blade noise is likely to occur.
As illustrated in
FIG. 13
, after an image forming operation is completed, a current fed to a photoreceptor drive motor, which drives the photoreceptor to rotate, is stopped. Thereafter, the photoreceptor rotates by inertia. When the number of revolutions (rpm) of the photoreceptor is decreased from the number of revolutions “a” (rpm) to substantially the number of revolutions “b” (rpm) at which the blade noise is likely to occur, the brake is put on the photoreceptor to stop the rotation of the photoreceptor as indicated by the dotted line in FIG.
13
.
When compared to a case in which a photoreceptor stops rotating by inertia (indicated by a solid line in FIG.
13
), a rotation time of the photoreceptor in a period between the number of revolutions “b” (rpm) and the number of revolutions “zero” is reduced from “Ta” (seconds) to “Tb” (seconds). As a result, the occurrence of the blade noise is prevented.
However, an image forming apparatus including a photoreceptor and a cleaning blade has another problem to be solved. Specifically, a foreign substance such as paper powder may attach to a leading edge of the cleaning blade, which thereby causes the useful lifetime of the cleaning blade to be decreased.
Referring again to
FIG. 13
, in order to remove such a foreign substance from the leading edge of the cleaning blade, the above-described background image forming apparatus controls the photoreceptor to rotate in a reverse direction for a predetermined time after the rotation of the photoreceptor is stopped. In the operations of the above-described background image forming apparatus, the operations for preventing the occurrence of the blade noise and for removing the foreign substance from the leading edge of the cleaning blade are separately performed.
SUMMARY OF THE INVENTION
The present inventors have recognized that an image forming apparatus which efficiently prevents occurrence of blade noise and removes a foreign substance from a leading edge of a cleaning blade at substantially the same time is heretofore not known in the art.
Accordingly, one object of the present invention is to address the above and other problems in the background art.
According to one aspect of the present invention, a control device to control an image forming apparatus includes a rotatable image bearing member configured to bear a toner image. A transfer device is configured to transfer the toner image from the image bearing member to a transfer material by applying a transfer bias to the transfer material. A cleaning device is configured to remove residual toner from the image bearing member by a cleaning blade. And, an image bearing member drive motor is configured to rotate in a forward direction and a reverse direction to drive the image bearing member to rotate in a forward direction and a reverse direction. The control device is configured to control the image bearing member drive motor to rotate in the reverse direction to brake the image bearing member and then rotate the image bearing member in the reverse direction after controlling the transfer device to stop application of the transfer bias, and to control the image bearing member drive motor to stop rotating the image bearing member after the image bearing member starts rotating in the reverse direction.
According to another aspect of the present invention, a method of forming an image in an image forming apparatus includes rotating an image bearing member to form an image thereupon, applying a transfer bias to a transfer material to transfer a toner image on the image bearing member to the transfer material, controlling an image bearing member drive motor to rotate in a reverse direction to brake the image bearing member and then rotate the image bearing member in the reverse direction after controlling a transfer device to stop application of the transfer bias, and to stop rotating the image bearing member after the image bearing member starts rotating in the reverse direction.
REFERENCES:
patent: 4806968 (1989-02-01), Watanabe et al.
patent: 4833378 (1989-05-01), Furue et al.
patent: 4931834 (1990-06-01), Suga
patent: 4967239 (1990-10-01), Sakakura
patent: 5280224 (1994-01-01), Sagara
patent: 5396319 (1995-03-01), Tokuhashi et al.
patent: 5463293 (199
Beatty Robert
Ricoh & Company, Ltd.
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