Hitachi Koki Co., Ltd.

Hitachi, Ltd.

Ricoh Printing Systems, Ltd.

Masami Ishikawa

Minoru Ohshima

Tsukasa Ogawa

Teruaki Mitsuya

Takao Umeda

Tsuneaki Kawanishi

Hisao Okada

Shigenobu Katagiri

Masayoshi Ishii

Kazutoshi Obara

Katsuhiko Suzuki

Takashi Nakazawa

Mitsugu Asano

Toshiaki Fujieda

Susumu Saitoh

Hirochika Okano

Tohru Miyasaka

In an image forming method, when viewed from the moving direction of a photosensitive bodythere is disposed, on the upstream side, a first developing rolleropposed to and adjacent to the photosensitive bodyand rotatable in the opposite direction to the photosensitive bodywhile the peripheral speed ratio of the rollerto the photosensitive bodyranges from 0.8 to 2.0; on the downstream side of the rollerthere is disposed a second developing rollerrotatable in the same direction to the photosensitive bodywhile the peripheral speed ratio of the rollerto the photosensitive bodyranges from 1.05 to 2.0; and the shape coefficient SFof the toners of two-component developing agent ranges from 120 to 170, while the shape coefficient SFranges from 110 to 130.

Image forming method and image forming apparatus

A device for measuring a surface potential at a photosensitive body including: a potential sensor for measuring surface potentials at a plurality of positions on the photosensitive body; a plurality of sample hold circuits; and an adder for adding each measured surface potential held in each sample hold circuit, or an adder which adds up each measured surface potential and average the sum. The addition or averaging of the measured values serves to eliminate eccentricity-induced errors and noise in the surface potential measurements, thereby allowing a correct surface potential to be obtained.

Device for measuring surface potentials at photosensitive body and

A double beam scan type optical apparatus for use in a laser printer or the like. Such apparatus comprises two light sources and a lens system which provide scanning means for scanning a surface with parallel output light beams of the two light sources and beam distance controlling means for controlling the distance between the light beams. The reliability of the invention is improved by monitoring the intensity of the beams. Beam intensity checking means provide signals to verify that the intensity of each beam is maintained equal thus assuring that no abnormal conditions exist with the light sources or the lens system of the apparatus.

Double beam scan type optical apparatus

An improved printing magnet drive device for use in a printing apparatus, such as line printer, is disclosed. The improvement comprises a constant voltage control means in which an output terminal voltage of a transistor is compared with a reference voltage and the comparison result is fed back to the transistor so as to control the output terminal voltage of the transistor to a predetermined value, whereby the voltage applied to the printing magnets is substantially maintained unchanged.

Printing magnet drive device

Growing community of inventors

Ibaraki, Japan

Masami Ishikawa