| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent occurrence of a false contour in a highlight part due to the variation of a start point of reproducing an image of low area ratio, in an image forming apparatus wherein a latent image is formed by exposing with an area ratio set for every pixel, forming a latent image by electric potential difference and transferring toner to the latent image. <P>SOLUTION: A plurality of pattern images having different area ratio are formed by a pattern signal generating apparatus 41 (pattern image forming means) in an area of low area ratio including an image reproduction start point setting value. The toner transfer part of the developed pattern image is detected by an image detecting sensor 42, and the data are binarized by a data processor 43, and the image reproduction start point is detected. The reproduction start point detection value is compared with the reproduction start point setting value by a controller 9 (reproduction start point control means), and a voltage to be applied by an electrifying power source 7 to an electrifying apparatus 2 or a voltage to be applied by a developing bias power source 8 to a developing roll 3a is adjusted so that the reproduction start point detection value and the reproduction start point setting value become nearly the same. <P>COPYRIGHT: (C)2007,JPO&INPIT |
