| 摘要 |
PURPOSE:To accurately detect the density of a patch image formed on an image carrier in spite of the eccentricity of the image carrier. CONSTITUTION:The patch image for density detection is formed in a developing position by a developing device 5 on a photoreceptor drum 1 having a home position M. The density of the patch image is detected by a density detection sensor 11 arranged on the downstream side of the developing device. An amount of eccentricity in each phase of the photoreceptor drum 1 with the home position M as a reference is stored in a storage device. The phase in a patch image forming position with the home position M as the reference is detected by a home position sensor 11. Thus, the amount of the eccentricity of the photoreceptor drum 1 in the position where the patch image is formed is detected, and by correcting the density of the output image of the patch image based thereon, accurate image density is obtained. |
