| 摘要 |
PROBLEM TO BE SOLVED: To perform highly accurate image density control by accurately performing the density detection of a patch on a transfer belt for each color even in the case that the transfer belt and an intermediate transfer body consist of a material incorporating a substance having the same absorption band as that of the toner of at least one color out of plural colors used. SOLUTION: When patch density is detected by using an optical sensor by which a normally reflected light quantity and an irregularly reflected light quantity by the patch on the transfer belt are simultaneously measured, though the density detection of the patch of black toner is not made possible at the sensor output value Vd of irregularly reflected light and the density detection of the patch of color toner is made difficult because of high density by the sensor output value Vm of normal reflected light, the difference Vm-Vd of sensor output are remarkably changed by the patch density for the black toner and the color toner, and the patch density is accurately detected, so that the patch density is detected by the difference value and image density control is performed based on it. The surface glossiness of the transfer belt is set to be >=50 and <=98 by the measuring angle of 20 deg.. |
