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US 5,966,560 AGranted
Image forming apparatus with enhanced pretransfer erasing
AssigneeMinolta Co., Ltd.
InventorsHideaki Kodama, Yasuhiro Ohno, Kazuomi Sakatani, Makoto Takase
Life of this patent
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Abstract
In an electrophotographic copying machine, image quality is improved by suppressing phenomena such as narrowing and thickening of a linear image or discharge noises in a photograph image due to anomalies on transfer of a toner image. For example, a document type is discriminated and when a transfer brush is used for transfer, transfer current and pretransfer erasing are controlled according to the type of document image. The pretransfer erasing is controlled in various following situations: Bi-level exposure method or multi-level exposure method, edge emphasis, photoelectric efficiency, the surface potential of the photoconductor, and position of a developing device.
Claims34
An image forming apparatus comprising:
- a photoconductor;
- a latent image forming device for forming a latent image on said photoconductor according to image data of a document;
- a developing device for forming a toner image on the latent image;
- a transfer device for transferring the toner image formed on said photoconductor onto a transfer material;
- a first decision means for deciding a first image attribute data of whether image data comprises bi-level data or multi-level data;
- and
- a controller which controls transfer pressure of said transfer device according to the first image attribute data obtained by said first decision means.
4 more elements
An image forming apparatus comprising:
- a photoconductor;
- a latent image forming device for forming a latent image on said photoconductor according to image data of a document;
- a developing device for forming a toner image on the latent image;
- a transfer device for transferring the toner image formed on said photoconductor onto a transfer material;
- a decision means for deciding an image attribute data of whether or not image data are dot image data;
- and
- a controller which controls transfer pressure of said transfer device according to the image attribute obtained by said decision means.
4 more elements
An image forming apparatus comprising:
- a photoconductor;
- an exposure device for forming an electrostatic latent image on said photoconductor according to image data;
- a developing device for forming a toner image on the latent image;
- a transfer device for transferring the toner image onto a transfer material;
- an eraser which removes charges from the surface of said photoconductor;
- a selection device for selecting an exposure gradation method to be used by said exposure device among bi-level exposure gradation method and multi-level gradation method;
- and
- a controller which sets a degree of removal of charges by said eraser according to the exposure gradation method selected by said selection device.
5 more elements
An image forming apparatus comprising:
- a photoconductor;
- an exposure device for forming an electrostatic latent image on said photoconductor according to image data;
- a developing device for forming a toner image on the latent image;
- a transfer device for transferring the toner image onto a transfer material;
- an eraser for removing charges from said photoconductor;
- a selection device for selecting a mode which enhances a difference in density of the image data;
- and
- a controller which sets a degree of removal of charges by said eraser according to whether or not the mode is set by said selection device.
5 more elements
An image forming apparatus comprising:
- a photoconductor;
- a sensitizing charger for sensitizing said photoconductor with a grid potential;
- an exposure device for forming an electrostatic latent image on said photoconductor according to image data;
- a developing device for forming a toner image on the latent image;
- a transfer device for transferring the toner image onto a transfer material;
- an eraser provided for removing charges from said photoconductor;
- a controller which sets a suitable grid potential of said sensitizing charger and further sets a degree of the removal of charges by said eraser corresponding to the set grid potential.
4 more elements
An image forming apparatus comprising:
- a photoconductor;
- a sensitizing charger for sensitizing said photoconductor;
- an exposure means for forming an electrostatic latent image on said photoconductor according to image data;
- a developing device for forming a toner image on the latent image;
- a transfer device for transferring the toner image onto a transfer material;
- an eraser for removing charges from said photoconductor;
- a potential sensor which detects a potential of the surface of said photoconductor after removing charges therefrom by said eraser;
- and
- a controller which sets a degree of the removal of charges by said eraser according to the potential detected by said potential sensor.
6 more elements
An image forming apparatus comprising:
- a photoconductor;
- a sensitizing charger for sensitizing said photoconductor;
- an exposure means for forming an electrostatic latent image on said photoconductor according to image data;
- a plurality of developing devices for forming a toner image on the latent image, said plurality of developing devices being arranged successively along a rotational direction of said photoconductor;
- a transfer device for transferring the toner image onto a transfer material;
- an eraser provided for removing charges from said photoconductor;
- and
- a controller which activates one of said plurality of developing devices for development and sets a degree of the removal of charges by said eraser in accordance with which one is activated among said plurality of developing devices.
5 more elements
An image forming apparatus comprising:
- a photoconductive member;
- a latent image forming device for forming a latent image on said photoconductive member according to image data of a document;
- a developing device for developing the latent image;
- a transfer device for transferring the toner image onto a transfer material;
- an eraser for discharging the surface of the photoconductive member developed by the developing device;
- and
- a controller for setting the amount of discharge of said eraser in accordance with a type of the document image,
- wherein when the document includes portions of different image types, said controller separately sets the discharge amount of said eraser for each portion.
5 more elements
Dependencies are inferred from the claim text.