Sharp Kabushiki Kaisha Corporation

Toshimitsu Goto

Kiyoshi Toizumi

Taisuke Kamimura

Katsumi Adachi

Masamitsu Sakuma

A developing device includes a developing roller and a toner charging roller. The toner charging roller has (a) a metallic layer which induces its electrons by receiving light irradiation, and (b) an ultraviolet irradiater which irradiates ultraviolet to the metallic layer. The toner charging roller gives the electrons to toner, so that the toner on the developing roller is charged. There is a space between the toner charging roller and the developing roller, and a grid electrode which controls a flow of the electrons is provided in the space. Thus, mechanical/thermal load given to the toner or the toner charging roller can be reduced, so that it is possible to prevent deterioration of toner and the device.

Developing device, charging method used therefor, and printing apparatus having the developing device

The developing device X includes: toner T that contacts an electrostatic latent image on a photosensitive drum D; a charging roller for charging the toner through contact; and an ultraviolet irradiator for charging the toner by shining ultraviolet light onto a sleeve of the charging roller from a position on the back of the sleeve via a roller . The sleeve of the charging roller contains material that changes its molecular structure under ultraviolet irradiation by the ultraviolet irradiator in such a manner to charge the toner. Deterioration of a charged member (toner) can be prevented, and so is fusion of the charged member with the charging means. Reliability in the developing process proves.

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Yamatokoriyama, Japan

Toshimitsu Goto