| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus constituted so that soiling on the back side of a transfer sheet can be prevented in the case of using a patch pattern, dispensing with the installation of a cleaning means for a secondary transfer apparatus. SOLUTION: The image forming apparatus 1 includes an intermediate transfer body 11 which is made movable along a plurality of image forming units arranged side by side, and the apparatus has the constitution 23 of primarily and successively transferring toner images from the image forming units to the intermediate transfer body, thereafter, secondarily transferring the superposed images to the transfer sheet in a mass. and the apparatus also has the constitution of forming a patch pattern to control image density on the intermediate transfer body 11, and optically detecting the patch pattern. In the case of continuously passing the transfer sheets, a sheet-to-sheet distance between the transfer sheets is made equal or exceeding the circumferential length by the amount of one rotation of a secondary transfer roller 23 for applying a secondary transfer bias, and regarding the position of forming the patch pattern P1, the pattern P1 is formed between the transfer sheets and in a position P1' so as to appear ahead of the leading end of the succeeding transfer sheet after the single rotation of the secondary transfer roller 23. COPYRIGHT: (C)2007,JPO&INPIT
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