发明授权
- 专利标题: Developing device for an image forming apparatus
- 专利标题(中): 用于图像形成装置的显影装置
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申请号: US430473申请日: 1995-04-28
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公开(公告)号: US5489747A公开(公告)日: 1996-02-06
- 发明人: Eiji Takenaka , Kazuhiro Yuasa , Shuichi Endoh , Iwao Matsumae , Yoshiaki Tanaka , Hiroshi Hosokawa , Mugijiroh Uno , Hiroshi Saitoh , Toshihiro Sugiyama , Tetsuo Yamanaka , Eisaku Murakami , Satoru Komatsubara
- 申请人: Eiji Takenaka , Kazuhiro Yuasa , Shuichi Endoh , Iwao Matsumae , Yoshiaki Tanaka , Hiroshi Hosokawa , Mugijiroh Uno , Hiroshi Saitoh , Toshihiro Sugiyama , Tetsuo Yamanaka , Eisaku Murakami , Satoru Komatsubara
- 申请人地址: JPX Tokyo
- 专利权人: Ricoh Company, Ltd.
- 当前专利权人: Ricoh Company, Ltd.
- 当前专利权人地址: JPX Tokyo
- 优先权: JPX6-092346 19940428; JPX7-062750 19950322
- 主分类号: G03G15/09
- IPC分类号: G03G15/09 ; G03G15/08
摘要:
A developing device for an image forming apparatus and having a relatively hard first developing roller formed with fine N-S magnetic poles on the periphery thereof, and a relatively soft second developing roller for conveying toner electrostatically transferred thereto from the first roller toward a photoconductive drum. The toner is charged by friction while being passed through between the first roller and a blade, and then magnetically deposited on the first roller. At a position where the first and second rollers contact each other, only the adequately charged toner is electrostatically transferred from the first roller to the second roller. The second roller conveys the toner toward the drum. As a result, the toner is brought to a developing position in an amount corresponding to a saturation or maximum image density. The second roller is made up of a metallic conductive core, a semiconductive foam layer, and an insulative surface layer implemented by resin. The real resistance between the core and the surface is selected to be higher than 10.sup.3 .OMEGA. but lower than 10.sup.13 .OMEGA.. The ratio of the real resistance associated with the maximum temperature change to the real resistance at normal temperature is selected to be less than or equal to 4 in absolute value.