Canon Kabushiki Kaisha

Toru Kosaka

Koichi Hiroshima

Katsuhiko Nishimura

Yasuo Yoda

Takashi Kawana

Kaoru Seto

Shinichi Tsukida

Shinichiro Maekawa

Manabu Sakakibara

An image forming apparatus has an image bearing member; toner image forming unit for forming a toner image with non-magnetic toner on an image bearing member; intermediate transfer member contactable to the image bearing member and movable along an endless path; primary transfer unit for effecting primary image transfer of the toner image formed on the image bearing member onto the intermediate transfer member at a first transfer position; secondary transfer unit for effecting a secondary image transfer of the toner image from the intermediate transfer member on the transfer material at a second transfer position; and a residual toner charger for charging the residual toner remaining on the intermediate transfer member to a polarity opposite from a regular polarity thereof. After the secondary image transfer, the residual toner remaining on the intermediate transfer member is charged by the residual toner charger to the opposite polarity, and is then passed through the first transfer position during the primary image transfer, so that the residual toner is transferred back to the image bearing member substantially simultaneously with a next primary image transfer, thus removing the residual toner from the intermediate transfer member.

Image forming apparatus which back-transfers residual toner from an

In an image forming apparatus a toner image is transferred onto a transfer material using an intermediate transfer member. The image forming apparatus has an image bearing member; a toner image forming unit for forming a toner image on the image bearing member; an intermediate transfer member movable along an endless path in contact with the image bearing member; a bias voltage applicator for applying a bias voltage to transfer the toner image from the image bearing member onto the intermediate transfer member at a first transfer position of the intermediate transfer member; and an image transfer device for transferring the toner image from the intermediate transfer member onto the transfer material at a second transfer position of the intermediate transfer member, a residual toner charge for charging residual toner remaining on the intermediate transfer member after image transfer therefrom, to a polarity opposite from a regular polarity of the toner to permit the residual toner to transfer back, simultaneously with a next image transfer at the first transfer position, to the image bearing member when the residual toner passes through the first transfer position.

Image forming apparatus having cleaning device for cleaning intermediate

An image forming apparatus includes a first image-bearing member such as an electrophotographic photosensitive member, an intermediate transfer member for receiving a transferable image formed on the first image-bearing member, and contact transfer device for transferring the transferable image from the intermediate transfer member to a transfer material. The first image-bearing member has a surface layer having a dielectric constant .epsilon..sub.d, the intermediate transfer member has a surface layer having a dielectric constant .epsilon..sub.ITD and the contact transfer device has a surface layer having a dielectric constant .epsilon..sub.tr satisfying a relationship of; .epsilon..sub.d .ltoreq..epsilon..sub.ITD .ltoreq..epsilon..sub.tr. The intermediate transfer member exhibits a volume resistivity of 10.sup.6 -10.sup.10 ohm.cm (at an applied voltage of 1 kV), and the contact transfer device exhibits a volume resistivity of 10.sup.8 -10.sup.15 ohm.cm (at an applied voltage of 1 kV). As a result, it is possible to obtain high transfer efficiencies in both primary and secondary transfer over a wide transfer bias application range.

Image forming apparatus having dielectric constant relationship between

On the basis of inputted multivalued image data, direction of growth is decided from a density pattern having a plurality of growth directions and a density pattern is caused to grow based upon the growth direction that has been decided. As a result, character images are formed sharply and high-quality half-tone images exhibiting reduced density irregularity can be produced.

Image processing system having variably controllable pixel density

An image processing apparatus in which a density pattern is generated which corresponds to input image data. Growth direction of the density pattern is controlled by generating a density pattern in a prescribed direction, and generating a density pattern in a direction based on a random signal. As a result, when printing the image data based on the generated density patterns, there is no joining between adjacent pixels and a high-quality image is produced.

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Machida, Japan

Toru Kosaka