Sharp Kabushiki Kaisha Corporation

Takao Hiroyasu

Jun Yamaguchi

Yasuyuki Ishiguro

Takahiko Kimura

Hiroshi Kawahito

Fumito Mizoguchi

Syouichi Fujita

Yoshiaki Sanada

Hideyuki Nishimura

Itaru Kawabata

Yoshiki Ichikawa

Hiroshi Kawamoto

Yuichi Kazaki

Masahiro Tsuji

Fumito Mizoguti

Shintarou Hatano

Impurities contained in a developer are captured and prevented from mixing into the developer again, thereby to avoid lowering of image quality due to the impurities. Such impurities include aggregates of the developer formed in a developing apparatus, insufficiently charged toner particles, defectively charged toner particles having an opposite polarity to a predetermined polarity, and defective carrier particles lacking in strength for being held by a developing magnet roller. A recess is provided between peaks of magnetism located in a lower portion of a developing magnet roller. The recess has an air pressure substantially equal to an air pressure (atmospheric pressure) in the developing apparatus, so that air in the developing apparatus and the recess does not flow only in one direction. Impurities contained in the developer circulating around the developing roller cannot be magnetically held in the lower half of the developing roller because of centrifugal force and gravity. Consequently, the impurities are separated and collected in the recess.

Developing apparatus

A developing device incorporating a developer supply unit and a developer discharge section, in which a supply developer including a mixture of toner and carrier is successively supplied to a developer container from the developer supply unit and a deteriorated developer in the developer container is discharged through the developer discharge section. The developer supply unit has a sponge roller for selectively attracting toner to a surface thereof, a magnet roller for selectively attracting carrier to a surface thereof, and a member for scraping and bringing the toner and carrier attracted to these rollers into the developer container. The developer including toner and carrier in a predetermined ratio is thus stably supplied to the developer container. In another example of the developer supply unit, agitating of the developer is performed while shovelling the developer deposited in a lower part of the unit by a transport screw. With this structure, since the toner and carrier are evenly mixed in the unit, the developer having a uniform toner concentration is supplied to the developer container, thereby continuing satisfactory development.

Developing device with developer-supplying mechanism

Growing community of inventors

Nara, Japan

Takao Hiroyasu