Sharp Kabushiki Kaisha Corporation

Kazumi Irie

Yoichi Shimazawa

Hideo Matsuda

Yasutaka Maeda

Osamu Fujimoto

Shunju Anzai

Hidekazu Sakagami

Syoichiro Yoshiura

Kazuyuki Ohnishi

Yoritaka Tsubaki

Atsushi Ide

Masao Yamamoto

Developing devices are provided adjacent to a light sensitive element. An intermediate transfer drum is provided adjacent to the light sensitive elements. After exposure of the light sensitive element, a first color or third color image is formed on the light sensitive element. On the other hand, after exposure of the light sensitive element, a second color or fourth color image can be formed on the light sensitive element. The first color image is transferred from the transfer unit to the intermediate transfer drum at the first transfer portion, and the second color image is transferred from the transfer unit at the second transfer portion so as to be superimposed on the first color image. Similarly, the third color image is transferred so as to be superimposed on the second image and the fourth color image is transferred so as to be superimposed on the third color image to the intermediate transfer drum. Accordingly, the first to fourth color images are superimposed. Thereby, downsizing of the device and cost reduction are achieved and image formation speed is facilitated.

Image formation apparatus and image formation method

A conventional image forming device having a plurality of image optical scanning recording sections has had a drawback of being incapable of correcting printing positions of the image optical scanning recording sections with high precision by using a small-scale circuit. In the case of an image forming device of the present invention, a variable clock generator 114 having a voltage control oscillator (VCO) 114a is provided therein as reference clock signal generating means of laser control system of each of image optical scanning recording sections (LSU) for cyan, yellow, and magenta. By so doing, during an invalid printing period prior to a valid printing period, frequencies of the reference clock signals of the LSUs for cyan, yellow, and magenta are adjusted in accordance with offsets of printing start positions of these LSUs with respect to that of the LSU for black, so that printing offsets are eliminated. As a result, the printing start positions are made to coincide with each other with high precision even with a small-scale circuit.

Image forming device

Since the paper entry guide is disposed below and in close proximity to a fixing belt, the leading edge of recording paper can become wavy or curled when operated in a high temperature, high humidity environment or when printing on the reverse side of the paper in double-sided print mode, and this has lead to the problem that the leading edge of the recording paper after transfer is not properly inserted in the narrow spacing between the paper entry guide and the fixing belt, resulting in a recording paper jam. A fixing device comprises a fixing belt stretched around a heating roller with a heat source contained therein and a fixing roller, a pressing roller for pressing the fixing roller from below via the fixing belt, and a paper entry guide disposed below and in close proximity to the fixing belt and upstream of a nipping portion composed of the fixing belt and the pressing roller. The paper entry guide is pivotably supported on a fulcrum. A solenoid is provided at the upstream side of the paper entry guide, and a return spring is disposed above the paper entry guide. The solenoid, when in the ON state, pulls a plunger to its lowermost position against the spring force of the return spring, and thereby rotates the paper entry guide in the clockwise direction about the fulcrum to maintain spacing with respect to the fixing belt.

Fixing device and fixing temperature control method

Growing community of inventors

Yamatokoriyama, Japan

Kazumi Irie