| 摘要 |
PROBLEM TO BE SOLVED: To achieve high-accuracy density measurement to reflect the measured result in optimum image density or gradation density by preventing patch toner from being deteriorated because of a retransfer phenomenon in a color image forming apparatus having intermediate transfer type tandem structure. SOLUTION: The image forming apparatus has the intermediate transfer type tandem structure where photoreceptor drums 1A and 1B for forming Y, M, C and K color component toner images are arrayed and an intermediate transfer body 16 coming into contact with the respective photoreceptor drums circularly turns. When a patch toner image 69A moves and reaches a density sensor 68 arranged on a more downstream side in a turning direction than the photoreceptor drum 1B while transferring the toner images formed on the photoreceptor drums 1A for Y, M and C colors, the intermediate transfer body belt 16 is separated from the photoreceptor drum 1B for K color which does not participate in image output by a cam 9 under control based on a signal obtained by detecting the density of the patch toner image 69A. COPYRIGHT: (C)2008,JPO&INPIT
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