Ricoh Company, Ltd.

Kenichi Ishiguro

Tsuyoshi Imamura

Makoto Nakamura

Kenji Narita

Kyota Koetuka

Kyohta Koetsuka

Takahiro Yasunaga

Takeo Araki

Yasuhiro Hujimori

A developing device which prevents bias of a developer caused by an axial magnetic force of a magnet roller, and which can form an image uniform in the axial direction; and a magnet roller for a developing device which is used in the above developing device and is reduced in axial magnetic force. The developing device includes a rotatable sleeve which carries a developer on the surface thereof, a fixed magnet roller which is provided within the sleeve and has a plurality magnetic poles, and a doctor blade which controls the amount of developer carried on the sleeve. The developing device is constructed so that among the plurality of magnetic poles of the magnet roller, the ratio of the axial magnetic flux density to the radial magnetic flux density of a magnetic pole opposing the doctor blade is 2.5/100 or less in a central portion in the axial direction.

Developing device and magnet roller for developing device

A developing roller is made up of a magnet member and a sleeve surrounding the magnet member. A sophisticated magnetic characteristic including a repulsive pole can be easily formed on the surface of the sleeve. The repulsive pole causes a developer to be sharply released from the surface of the sleeve. A developing device including the developing roller is also disclosed.

Developing device and developing roller therefor

A cylindrical structural body for use in an image forming apparatus and a method of producing the same are disclosed. The structural includes a cylindrical sleeve and flanges or similar end members respectively affixed to opposite ends of the sleeve. The flanges can be firmly and easily affixed to the sleeve without causing the sleeve to deform. The structural body is therefore low cost and highly accurate.

Cylindrical structural body for use in an image forming apparatus and

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Kanagawa, Japan

Kenichi Ishiguro