Electrophotography – Cleaning of imaging surface – Blade
Reexamination Certificate
2001-10-17
2003-05-06
Tran, Hoan (Department: 2852)
Electrophotography
Cleaning of imaging surface
Blade
C399S071000
Reexamination Certificate
active
06560438
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to image formation apparatuses such as copiers, printers, facsimile machines, or compound machines of these. More particularly, the present invention relates to electrophotographic image formation apparatuses wherein charging, recording, development, transfer, cleaning and the like are repeated to form toner images on image substrates sequentially, and the toner images are transferred sequentially to record the images onto a transfer material such as a sheet of paper, an OHP film, an intermediate transfer material, or the like. More specifically, the present invention relates to a method of removing deposit from the image substrate, and an image formation apparatus using the method, wherein deposit, such as discharge products deposited on the image substrate in the image formation apparatus, is removed.
BACKGROUND OF THE INVENTION
Conventionally, in electrophotographic image formation apparatuses, when a charge bias is applied on the image substrate, discharge products such as ozone, nitrogen oxides and the like get deposited on the image substrate. As a result, there is a flow of charge through the deposited section causing image deletion, and image quality of the toner image recorded on the transfer material is thus degraded.
In conventional image formation apparatuses, after the toner image is transferred onto the transfer material from the image substrate, transfer residual toner remaining on the image substrate is removed with a cleaning device. During this cleaning, the cleaning device, which is generally a cleaning blade, removes a portion of a photosensitive layer of the image substrate along with the deposited discharge products.
It is disclosed in Japanese Laid Open Patent Application No. 2000-47545 that, existence of nitrates deposited on the photosensitive body surface is detected when a driving torque of a photosensitive body reaches a predetermined torque. If the existence of nitrates is detected, only then a developer is supplied actively to the photosensitive body that is rotated to clean the body by scraping off the nitrates together with the developer.
Further, Japanese Laid Open Patent Application No. 2000-39819 discloses formation of toner image for cleaning by following method. That is, switching off the charge bias of a charging unit; not exposing with an exposure unit; and switching on intermittently a DC component of a development bias of a development unit.
Moreover, Japanese Laid Open Patent Application No. 2000-39819 discloses formation of toner image for cleaning by following method. That is, switching on intermittently the DC component of the charge bias of the charging unit, not exposing with the exposure unit, and switching on intermittently the DC component of the development bias of the development unit; or by switching on continuously the DC component of the charge bias of the charging unit, exposing intermittently with the exposure unit, and switching on continuously the DC component of the development bias of the development unit.
Following measures have been taken in the past to improve the life span of the image substrates. For example, surface of the image substrate is covered with a photosensitive layer comprising a hard protective layer for preventing abrasion of the photosensitive layer, or the photosensitive layer is composed of hard amorphous silicon. However, in such cases, the photosensitive layer cannot be properly scraped off with the cleaning device. In other words, there is a problem that the deposit entrapped inside concaves on the surface of the image substrate cannot be removed completely.
There are known image formation apparatuses that use toners containing abrasive particles. The toner is actively deposited onto the image substrate to form toner image, and the toner image is transmitted to the edges of the cleaning blade instead of being transferred onto the transfer material, and the deposit on the image substrate together with the toner are scraped off.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image formation apparatus which can completely removal deposit such as residual toner from an image substrate that has a hard layer on its surface.
It is another object of the present invention to enable the removal of the deposit without having to secure an independent period of time especially for the removal, without disturbing an image formation operation.
It is still another object of the present invention to remove the deposit regularly in order to prevent degradation of image quality on the transfer material infallibly.
It is still another object of the present invention to make the removal of the deposit executable particularly when required in accordance with surrounding environment.
It is still another object of the present invention to operate the removal of the deposit during operations other than the image formation operation, such that the deposit removal operation does not interfere with the image formation operation.
It is still another object of the present invention to deposit a toner to an optimum extent that prevents upcurve of the cleaning blade, onto the image substrate, in order to facilitate the removal of deposit during the deposit removal operation using a configuration that is as simple as possible.
It is still another object of the present invention to improve cleaning performance in order to achieve complete removal of the deposit such as discharge products from the image substrate, while preventing any upcurve of the cleaning blade.
It is still another object of the present invention to prevent “filming”, to minimize depositing on the image substrate and to enhance detachment of the deposit from the image substrate.
It is still another object of the present invention to provide an image formation apparatus wherein one or more of the above-mentioned objects are achieved.
The image formation apparatus according to the present invention comprises: an image substrate having a surface, a rotating unit that rotates said image substrate, a bias applying unit which applies a charge bias to said surface of said image substrate; a development unit that supplies a toner onto said surface of said image substrate; and a cleaning unit which includes a cleaning blade that removes the material deposited on said surface of said image substrate. This image formation apparatus performs a deposit removal operation at a predetermined time while no charge bias is applied to said surface of said image substrate. The deposit removal operation includes rotating the image substrate, supplying the toner to said surface of said image substrate to an extent that upcurve of the cleaning blade is not caused, and removing the deposited material on said surface of said image substrate.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 4499849 (1985-02-01), Tomita et al.
patent: 4547059 (1985-10-01), Nagayama et al.
patent: 4571070 (1986-02-01), Tomita
patent: 5105222 (1992-04-01), Ohta et al.
patent: 5530538 (1996-06-01), Godlove
patent: 6122648 (2000-09-01), Sakamoto et al.
patent: 6249304 (2001-06-01), Sawayama et al.
patent: 6295437 (2001-09-01), Hodoshima et al.
patent: 6308027 (2001-10-01), Obu et al.
patent: 6405015 (2002-06-01), Suzuki
patent: 6438337 (2002-08-01), Abe
patent: 0 926 559 (1999-06-01), None
patent: 5-107991 (1993-04-01), None
patent: 5-181295 (1993-07-01), None
patent: 6-67500 (1994-03-01), None
patent: 10-91049 (1998-04-01), None
patent: 11-219086 (1999-08-01), None
patent: 2000-39819 (2000-02-01), None
patent: 2000-47545 (2000-02-01), None
Ricoh & Company, Ltd.
Tran Hoan
LandOfFree
Method for removing deposit from image substrate and image... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for removing deposit from image substrate and image..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for removing deposit from image substrate and image... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3021681