| 摘要 |
PURPOSE:To accurately control toner even in case of dirt of a texture by multiplying the preceding measured texture voltage by a certain coefficient and using this result voltage as the reference voltage which is used as the threshold to discriminate a pattern voltage and a texture voltage. CONSTITUTION:A read pattern 10 is formed on the outside of an image area 11 on a photosensitive drum 1. The pattern 10 is electrically read by a pattern sensor 8 and converted to a pattern voltage Vsp, and the texture of the drum 1 is electrically read and converted to a texture voltage Vsg. Toner is replenished to a developing device 4 in accordance with a ratio of data of the voltage Vsg to the voltage Vsp. The prescribed reference voltage which is used as the threshold to discriminate voltages Vsp and Vsg is set to the value obtained by multiplying the preceding measured texture voltage Vsg by a certain coefficient. Thus, the toner concentration is always accurately controlled through the reflectance of the texture part is reduced because of the secular change of the photosensitive body, toner sticking, or the like. |
