Matsushita Electric Industrial Co., Ltd.

Yuji Nagai

Yuzo Kawano

Yoshihiro Mizoguchi

Kazunori Kanekura

Tadashi Shimotoso

Takashi Yoshihara

Kazuhiro Seguchi

Kazuhiro Ogata

A color image forming apparatus comprises photoconductor drums on which toner images of each color are developed and formed; an endless intermediate transfer belt arranged in a contactable state with the photoconductor drums to run; first bias transfer rollers which perform first bias transfer in which the toner images of each color are transferred from the photoconductor drums onto the intermediate transfer belt; a second bias transfer roller which performs second transfer in which the toner images on the intermediate transfer belt are transferred onto paper; and a separation unit which, when a maximum print length of an image is below a length from a transfer point A to a transfer point B, separates the photoconductor drums and the intermediate transfer belt from each other after all first bias transfer of the toner images to be transferred on the last paper in a first print job has been completed, before second bias transfer onto the last paper is started and after second bias transfer onto paper immediately before the last paper has been completed.

Image transfer section of color image forming apparatus

Disclosed here is a color-image forming apparatus that minimizes damage caused by friction between a photosensitive drum and an inter-stage transfer belt. The apparatus includes a plurality of image-forming units, each of which has the photosensitive drum carrying an electrostatic latent image thereon, a developing unit forming a toner image by applying toner to the latent image. Having different color toners therein, the image-forming units are organized into a tandem layout. The inter-stage transfer belt is looped over plural rollers to form an endless path. While traveling the path along the direction in which the image-forming units are arranged, the belt forms a full-color toner image thereon by transferring plural toner-images on the drums one upon another. The belt is controlled to come into contact with the drums only while accepting the toner image from the drums.

Color image forming apparatus that minimizes contact between transfer belt and photosensitive drum

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Kurume, Japan

Yuji Nagai