Casio Computer Co., Ltd.

Casio Electronics Manufacturing Co., Ltd.

Takeo Hirono

Mitsugu Oishi

Tadao Yamamoto

Moriyuki Kouroku

Noriki Ono

Toshiro Honda

Takao Yorifuji

Tatsumi Shimanari

Tetsuya Abe

Yoshiharu Abe

Hidefumi Kanai

Masaaki Dohi

Shinichi Hisatomi

Mitsuo Hayashi

A developing device used in an image forming apparatus has a developing roller at a lower opening of a toner hopper, and the developing roller contacts a photosensitive drum to form a developing portion therebetween. The hopper stores nonmagnetic toner and is provided with a toner stirring member and a toner feed roller being in press-contact with the developing roller in a lower part of the hopper. A doctor blade contacts a circumferential surface of the developing roller on an upstream side of the developing portion in a rotation direction of the drum. A conductive scooping sheet contacts the circumferential surface of the developing roller on a downstream side of the developing portion. A residual toner not used to develop a latent image on the drum and left on the developing roller is passed under the sheet into the hopper with the rotation of the developing roller. A sheet bias voltage ranging from 0V to -250V is applied to the sheet, so that an attaching force of the residual toner to the developing roller is weakened so that the residual toner can be easily removed by the feed roller.

Developing device, image forming unit and color image forming apparatus,

A method of forming an image without cleaning on the basis of repeated electrophotographic process cycles. Each process cycle includes charging a surface of a photosensitive drum to a predetermined polarity, and irradiating the charged surface of the photosensitive drum with light which carries image information, thereby forming a latent image corresponding to the image information. The latent image is visualized by using a dry developer material, and the visualized image is transferred from the surface of the photosensitive drum onto a transfer medium. The developer material contains a transfer accelerator (hydrophobic silica or light-transmitting fine powder) for improving efficiency for transfer of the visualized image onto the transfer medium.

Method of forming electrophotographic image

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Akishima, Japan

Takeo Hirono