| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the waste of toner constituting a patch being a toner image (patch) for detecting image density. SOLUTION: A magenta toner image (patch) 8M for detecting the image density is formed on a photoreceptor drum for magenta 11M by an image forming unit for magenta, and transferred to a transfer belt 30 rotating in a direction shown by arrow (b), and the density is detected by a density detection sensor 5. By applying a bias having the same polarity as the patch 8M to a transfer roller 15M by the transfer power source 71M of a voltage applying means 7M, the patch 8M after detecting the density is re-transferred to the drum 11M from the belt 30 and recovered by a cleaning device 14M so as to be utilized for the development of an electrostatic latent image. Other cyan, yellow and black patches are re-transferred to the photoreceptor drums for respective colors in the same manner.</p> |
