Sharp Kabushiki Kaisha Corporation

Tsuyoshi Miyamoto

Yasutaka Maeda

Taisuke Kamimura

Hideyuki Nishimura

Yukihiko Ueno

Katsuhiro Nagayama

Kyouichi Takata

Kazuyuki Ohnishi

Masato Tokishige

Natsuko Tanaka

Hiromi Washio

Yoichi Shimazawa

Osamu Fujimoto

Tokiyuki Okano

Kiyoshi Inamoto

Yuichi Kazaki

Kazunori Sohda

Etsuzi Nukushina

Koji Shinkawa

Shouichi Fujita

An electrophotographic image forming apparatus for transferring a visible toner image formed on a photoconductive body onto an intermediate transfer body primarily and transferring the toner image transferred on the intermediate body onto a paper secondarily is disclosed. In the electrophotographic image forming apparatus, the toner remaining on the photoconductive body is removed by a first cleaner blade after the primary transfer, and the toner remaining on the intermediate transfer body is removed by a second cleaner blade after the secondary transfer. A contact pressure of the second cleaner blade to be applied to the intermediate transfer body is set to be larger than a contact pressure of the first cleaner blade to be applied to the photoconductive body.

Image forming apparatus having intermediate transfer member

A full color copying machine which includes intermediate transfer medium whereon toner images having respective color components, formed on a photoreceptor are transferred to form one color toner image, and a screen filter disposed so as to be freely inserted or removed in or from a path of exposure light, which filters the exposure light for exposing the photoreceptor into a pattern of lines. A plurality of color toner images obtained by executing a plurality of copying processes based on a plurality of exposures applied to an original document are superposed on the intermediate transfer medium to form a color toner image. The copying machine further includes a screen mode for inserting a screen filter into a path of exposure light and a normal mode for removing the screen filter from the path of exposure light. Thus, exposures intended for low density components and high density components in an original document image are respectively performed by the use of the different modes, or they are respectively performed by changing setting conditions of the screen filter in the screen mode. With these arrangements, efficient application of the exposure device and high quality of the copied images can be achieved.

Full color copying machine

A transfer unit including: a transfer belt onto which toner images are formed; a backup roller on which said transfer belt is applied, the metallic surface of said backup roller being coated with a dielectric film; a metallic transfer roller that is disposed opposite to said backup roller across said transfer belt and to which a predetermined transfer voltage is applied, said transfer roller pressing copy paper against said backup roller with said transfer belt placed therebetween so that said toner images formed on said transfer belt are transferred onto said copy paper to be transported between said transfer roller and said transfer belt; and a back plate that is located in the vicinity of said backup roller and that contacts the back surface of said transfer belt, whereby an electric field for transferring a toner image by a low transfer voltage can be created, thereby preventing the transfer belt from dielectric breakdown.

Transfer unit

A cleaning structure of an image forming device comprises an image retainer, a cleaning blade supported to touch a moving surface of the image retainer, a cleaning roller supported to touch the moving surface of the image retainer in a position downstream from the position of the cleaning blade. The cleaning roller comprises a roller shaft, a roller base layer and a fluorocarbon polymer layer which is excellent in noncohesiveness and slip property.

Cleaning structure for moving image retainer for use in an image forming

A method of cleaning a photosensitive member in an electrophotographic apparatus in which an electrophotographic operation is performed by charging the photosensitive member with a predetermined voltage, exposing the charged photosensitive member so as to form a latent image thereon and developing the latent image by use of toner, includes the steps of charging the photosensitive member with a half tone level voltage which is smaller than the predetermined voltage, and developing the charged photosensitive member by use of toner without exposing the charged photosensitive member, so as to form a uniform half tone toner image thereon. The cleaning method also includes the step of scraping off the toner of the uniform half tone toner image from the photosensitive member by a blade abutting thereto.

Electrophotographic apparatus and method of cleaning the same

An electrophotographic apparatus having: a developer unit that has a magnetic developing roller for applying toner to electrostatic latent image areas formed on the surface of a photoconductor and that has a shutter which is closed to regulate the distribution of the toner to the photoconductor, a developing bias voltage for controlling adherence of the toner to the photoconductor being applied to said developer unit; and a bias voltage source for applying, when the shutter of the developer unit is closed, a developing bias voltage of the level between 0V and the developing bias voltage applied when the shutter is opened, thereby preventing blank spots from appearing in transferred images without increasing image-overtoning and also preventing damages from being caused to the surface of the fuser rollers of a fuser unit.

Electrophotographic apparatus with variable bias voltage

A copying apparatus having a prescanning function for obtaining density data to adjust copy parameters includes a correction function which eliminates the data obtained from a portion of a predetermined color, from the density data detected on a prescanning process. The density data can be restricted within a predetermined range. The predetermined range can be easily set by the user.

Copying apparatus

A light source device for use in a color copying machine comprises a plurality of light source lamps having different efficiencies respectively and means for lighting any number of light source lamp or lamps among said plural light source lamps depending on the luminous energy of the respective blue, green and red spectrums and/or the spectral sensitivity of the photosensitive member for said respective spectrums.

Light source device for use in a copying machine

A color copier operable both in monochromatic and full-color copying modes is controlled by a central processing unit programmed to exercise a real-time control of operation by detecting image characteristics of an original to be copied if a monochromatic copying mode is selected. If a full-color copying mode is selected, the image characteristics are preliminarily detected by scanning before a copying operation is started.

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Osaka, Japan

Tsuyoshi Miyamoto