Electrophotography – Control of electrophotography process – Control of transfer
Reexamination Certificate
1998-09-09
2001-06-19
Brase, Sandra (Department: 2852)
Electrophotography
Control of electrophotography process
Control of transfer
C399S049000
Reexamination Certificate
active
06249656
ABSTRACT:
This application is based on application No. 9-245842 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to an image forming apparatus, and more particularly, to an image forming apparatus that charges and exposes a photosensitive member rotated in one direction and develops the latent image on said image carrier into a toner image, and that transfers said toner image onto a belt or a sheet of paper conveyed on the belt.
2. Description of the Related Art
AIDC (auto-image density control) has conventionally been used in the areas of electrophotographic copying machines and laser printers, where, for the purpose of toner supply or image stabilization, a test pattern is formed on the photosensitive member using prescribed image forming parameters and the toner density of the test pattern is optically detected by a sensor to be fed back to either the supply of toner to the developer tank or to image forming parameters (such as photoreceptor charging voltage, exposure light amount and developing bias voltage).
On the other hand, in order to perform cleaning to remove the toner remaining on the photoreceptor, such means as application of an electric field prior to cleaning, erasure of the charge, or the use of a brush-type cleaner as a cleaner blade have been employed in order to stabilize and improve the cleaning performance.
These conventional cleaning improvement measures are intended for cleaning of the image forming unit. They assume that the transfer efficiency is approximately 90%, and therefore attempt to remove the remaining toner, which amounts to approximately 10%. However, in the test toner pattern formed using AIDC, 100% of the toner remains. This imposes an increased burden on cleaners, including those that incorporate said improvement measures, to clean said toner, and is one of the factors that accelerate the deterioration of the cleaner blade. It therefore leads to the problem that there still is toner remaining even after the cleaning.
In a color image forming apparatus in particular, due to the strong demand for high-quality images, the number of test patterns formed increases due to increased AIDC and the controlling of halftone density. This in turn increases the burden on the cleaner.
OBJECTS AND SUMMARY
The object of the present invention is to provide an image forming apparatus that performs the cleaning of the test toner patterns formed during AIDC using not just one cleaner but other cleaners as well, so that the burden on the cleaners may be reduced.
In order to achieve said object, the present invention provides an image forming apparatus that includes the following components:
an image carrier that is rotated;
a developing device that forms a toner image on said image carrier, said developing device forming a test toner pattern on said image carrier at a prescribed time;
a transfer device that transfers said toner image or test toner pattern onto a recording medium located on a recording medium carrier at a transfer area;
a first cleaning device that removes the remaining toner on said image carrier;
a second cleaning device that removes the remaining toner on said recording medium carrier;
a detecting device that detects the toner density of the test toner pattern; and
a control device that, when the test toner pattern whose toner density is detected by said detecting device passes through the transfer area, reduces the output of said transfer device to be smaller than the output used when a toner image is transferred.
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Inada Yasuyuki
Watanabe Toshifumi
Brase Sandra
McDermott & Will & Emery
Minolta Co. , Ltd.
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