Ricoh Company, Ltd.

Norimasa Soumiya

Junji Kurokawa

Toshio Nakahara

In the roller charging apparatus according to the present invention, the charging roller includes a layer of an epichlorohydrin rubber, so that it is possible to eliminate electric nonuniformity of a conductive elastic layer and to be charged by loading only a DC voltage. The charging roller also may have a surface layer formed of polyamide resin or fluorine resin. In addition durability can be improved by setting the roller hardness of the charging roller to 42 (measured by a JISA hardness meter) or more. Further, a roller diameter D.sub.r of the charging roller and drum diameter D.sub.d of the photosensitive drum may satisfy the relation of D.sub.d /D.sub.r .gtoreq.4. A cleaner can also be provided for removing foreign materials, such as toner, from the charging roller, and the cleaner may have a rubber hardness less than that of the charging roller.

Roller charging apparatus and image forming apparatus using the same

An electrophotographic copying machine capable of suppressing the formation of phantom images with a simple structure is provided. The machine includes a pre-transfer exposure lamp for irradiating a toner image formed on an imaging surface and a post-transfer exposure lamp for irradiating the imaging surface after separation of a transfer medium, to which the toner image has been transferred, from the imaging surface. The pre-transfer exposure lamp is provided to ease the transfer of toner image to the transfer medium and the post-transfer exposure lamp is provided to remove residual charge from the imaging surface thereby preparing the imaging surface ready to be used for the next cycle of copy operation. In the present invention, a ratio of light amount of the post-transfer exposure to the light amount of the pre-transfer exposure is maintained within a predetermined range, preferably 30-60%.

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Souka, Japan

Norimasa Soumiya