Minolta Camera Kabushiki Kaisha

Nitto Kogyo Co., Ltd.

Hodaka Kogyo Co., Ltd.

Tetsuya Yamada

Sanji Inagaki

Fumitoshi Atsumi

Hiroshi Okamoto

Hiroshi Goto

Yoshihiro Hattori

Masaaki Yamamoto

Hiroshi Fukao

Youichi Ishikawa

Shoichi Tsuge

Isao Iizaka

Kesaaki Kitazawa

Etsuaki Urano

Kenji Takahashi

Junichi Tamaoki

Toshiaki Ishihara

Naotaka Nishikawa

An image forming apparatus wherein a multicolored image of an original is formed in color on a sheet in one cycle of image forming operation. The apparatus comprises a plurality of developing devices which are filled with respective developers colored differently from each other and a scorotoron charger disposed between the developing devices for recharging on electrostatic latent image on a photosensitive member processed by the upstream developing device with the polarity opposite to the polarity charged beforehand. The developing device located upstream of the scorotron charger functions to develop the imaged portions including primary information which were charged with first potential. The scorotron charger recharges the electrostatic latent image with the opposite polarity, thereby lowering the potential of the other imaged portions including background information which were charged with second potential. The image portions charged with the second potential are developed in low density by the downstream developing device, portions with the second potential finely contrast with each other can be formed.

Multicolor image forming apparatus using chargers with opposite polarity

A heat fixing unit in an electrophotographic copying apparatus is disclosed. The heat fixing unit comprises a heat fixing roller with a heater, a pressure roller with a plurality of fibers, and driven ring components disposed on the ends of the pressure roller for adjusting the contact amount between the heat fixing roller and the pressure roller. The heat fixing unit offers a less warming up time and a better paper delivery performance, and requires less material cost. The heat fixing unit in an electrophotographic copying apparatus may employ a fixed type or a rotary type curing unit for raising the plurality of fibers.

Heat fixing unit in an electrophotographic copying apparatus

Disclosed is an oil applying roller provided in contact with the surface of a fixing roller of an electrophotographic copying apparatus. The oil applying roller comprises a core member, an oil retaining layer and a surface layer. The surface layer has less oil retaining ability than that of the oil retaining layer. Thus the oil applying roller can supply a small amount of oil to the fixing roller stably.

Oil applying roller for use in an electrophotographic copying apparatus

A photoreceptor charge control arrangement to be employed for electrophotographic copying apparatuses wherein a specific circumferential portion on a uniformly charged photoreceptor is first exposed by a referenced exposure source to a specific amount of exposure and successively, the surface potential of the circumferential portion mentioned above is detected either at the relative position immediately before a position for an imagewise light exposing station or at the position juxtaposing the position of the station mentioned above, so that the successive comparison of the surface potential thus detected with a fixed reference is capable of effectively providing an appropriate control signal which can be employed to compensate the amount of exposure of the exposure source, irrespective of the surface condition of the photoreceptor.

Electrophotographic density control

The operation of a slit exposure type copying apparatus is controlled to avoid overheating of a transparent cover for the original supporting station by controlling either, or both, of the excitation of the exposure lamp and the return movement of the movable scanning of the original. A detector switch is mounted in the path of movement of the scanning mechanism and is actuated thereby to deenergize the exposure lamp means when the scanning mechanism has travelled a distance substantially equal to that distance required to scan the original. A minimum distance of travel for the scanning means is defined and includes at least one second detector switch which is exposed in the path of movement of the scanning mechanism and is actuatable thereby to return the scanned mechanism to its initial position. The scanning means is caused to move until the actuation of the second detector switch if the first detector switch is actuated prior thereto, or to continue movement when the second detector switch is actuated prior to the first detector switch.

Slit exposure type copying apparatus

Growing community of inventors

Aichi, Japan

Tetsuya Yamada