Ricoh Company, Ltd.

Toshio Nakahara

Junji Kurokawa

Kazuo Nojima

Masako Chiba

Nobuo Kasahara

Yuji Sawai

Norimasa Soumiya

An electrophotographic image forming apparatus using a charge roller for uniformly charging the surface of a photoconductive element, or image carrier, during image formation, and a charging device having the charge roller. The charging efficiency is enhanced, and a uniform charge distribution is set up by the application of a DC voltage only. This suppresses the increase in the cost of an apparatus, the increase in power source cost, and the generation of a great amount of ozone. As a result, a charging member and a photoconductive element are prevented from being deteriorated while environmental pollution is eliminated.

Image forming apparatus and charging device thereof

In a charging device included in an image forming apparatus for charging an image carrier uniformly, a charge roller has an elastic layer and a surface layer. The elastic layer is made of a substance having a medium electric resistance and having no conductive particles dispersed therein. The surface layer is made of a non-adhering substance having a greater non-adhering property than the substance constituting the elastic layer.

Charge roller for an image forming apparatus

Image forming apparatus which maintains a temperature of a charge roller

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

A method of cleaning a transfer drum, which is located to face a photoconductive drum, to remove a toner left untransferred on a transfer film which is wound around the transfer drum. A fur brush rotatable in contact with the transfer drum for removing the toner from the drum and a toner collecting roller rotatable in contact with the fur brush for removing the toner from the brush are prepared. Before the fur brush begins cleaning the transfer film, the toner collecting roller collects the toner deposited on the fur brush. The fur brush is prevented from rubbing itself against a clamping section which is provided on the transfer drum for retaining a paper sheet. The transfer film is discharged while being cleaned. Before the transfer drum is cleaned, the photoconductive drum is cleaned twice or more.

Method of cleaning a transfer drum of an electrophotographic apparatus

A device for driving a photoconductive drum of an electrophotographic copier and others is operable without the need for gears, a toothed belt and other transmission mechanisms. An outer roller type drive motor is interposed between the drum and a drum support shaft such that an outer wheel portion of the motor drives the drum by way of an engaging member. Those members with which the body of the motor and that of the copier are engaged are made of a vibration-damping material. Tapered portions which are axially movable into and out of contact with each other are provided in a drive transmitting section with which an output portion of the motor and one end of the drum are engageable. Pressing means for causing one end of the drum into contact with the outer wheel portion of the motor through the tapered portions is provided at the other end of the drum.

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Yokohama, Japan

Toshio Nakahara