Fujitsu Corporation

Hideaki Iwasaki

Kunihiko Sato

Sachio Sasaki

Akira Nagahara

Shin Araki

Masatoshi Kimura

Hiroshi Nou

Masao Konishi

Kenji Fuke

Shigenobu Utaka

Toshio Tooda

Akiyoshi Iwamasa

Ryo Kitao

Futoshi Okabayashi

Takamasa Araki

A magnetic brush developing apparatus includes a development container containing a developer. A magnet is stationarily located in the development container and has magnetic poles radially provided on a plurality of points. A rotational sleeve is arranged to cover the outer circumference of the magnet and is rotatably driven to carry the developer in the development container. A blade is arranged opposite to the rotational sleeve to restrict the amount of the developer which is carried by the rotational sleeve. To obtain a uniform image quality without unevenness among different developing apparatus and a wider range of assembling precision to thus facilitate the installment of the apparatus, at a position facing the developer restriction member, and in its vicinity, there is formed a uniform magnetic flux density section having a magnetic flux density whose vertical component is substantially uniform on the periphery of the rotational sleeve.

Magnetic brush developing apparatus

A magnetic brush developing apparatus, comprising: a development container (102) for containing a developer; a magnet (122) stationarily located in the development container and having magnetic poles radially provided on a plurality of points; a rotational sleeve (121) arranged to cover the outer circumference of the magnet and rotatably driven to carry the developer in the development container to an image carrying body (131); and a blade (123) arranged opposite to the sleeve to restrict the amount of the developer which is carried by the sleeve. Two of the magnetic poles are a developing magnetic pole (Pd) facing opposite to the image carrying body (131) and a developer transfer magnetic pole (Pt) located between the developing magnetic pole (Pd) and the blade (123). A magnetic brush of the developer formed on the sleeve (121) by the developer carrying magnetic pole (Pt) has a magnetic flux density. A width or angle of a region where a radial component of the magnetic flux density exceeds over a half of a maximum value thereof, i.e., a half value width, is determined in such a manner that the developer is prevented from flying away from the magnetic brush.

A toner image transferring device is applied to, for example, an electrophotographic printer for electrostatically transferring a charged toner image from a photosensitive drum to a sheet or paper. The device encompasses a transfer charger disposed near the drum to form a clearance therebetween for feeding an electric charge to the sheet or paper through which the sheet or paper is passed, an electric source for supplying an electric energy to the transfer charger to give the sheet or paper an electric charge having a polarity opposite to that of the charge of the toner image, and a controller for controlling the electric energy output from the electric source the transfer charger so that a leading edge of the sheet or paper can be prevented from being excessively charged.

Transferring device controlled for preventing the leading edge of a

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Kashiwa, Japan

Hideaki Iwasaki