| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus designed such that time taken to detect patch patterns is shortened and the detection accuracy is enhanced, vibration of an intermediate transfer body affecting the detection accuracy is restrained and, in addition, patch patterns in all different colors can be securely formed and the size and cost reductions are achieved. SOLUTION: In the image forming apparatus, an image is formed on an intermediate transfer belt 15 by primarily transferring a toner image formed on a drum-like photoreceptor, and the image on the intermediate transfer belt is secondarily transferred by a secondary transfer roller 25 disposed in contact with the intermediate transfer belt, and thereby the image is finally formed on a transfer material such as paper or an OHP film. In this case, if the width of the intermediate transfer belt is A, the width of the secondary transfer roller is B, and the width of the transfer paper passed between them is C, the relation expressed by A>B>C is satisfied. A patch pattern formation area is provided in part of the intermediate transfer belt, with which the secondary transfer roller does not come into contact. A reflective photo-sensor 30 for detecting the patch patters Py, Pc, and Pm formed in the area is also provided. COPYRIGHT: (C)2007,JPO&INPIT
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