| 摘要 |
PURPOSE:To make the toner density of images constant by using the temperature rise detection value of high-sensitivity photoreceptor for control input. CONSTITUTION:A temperature detector 24 is provided near the surface of a high- sensitivity photoreceptor drum 15 and is connected to the control unit 30 which controls the bias voltage of the magnetic brush 27 of a developing device. As a result of this, when the high-sensitivity photoreceptor drum 15 revolves in the arrow u direction and charging, exposure, developing, transfer and cleaning are accomplished subsequently by the device group disposed around the same, the surface temperature change of the high-sensitivity photoreceptor drum 15 is detected and is inputted to a feedback circuit 26. Along with the temperature change, a variable resistor 28 is controlled so that the bias voltage of a magnetic brush 27 is changed, whereby the contrast potentials are maintained always constant irrespective of the change of the surface temperature of the high-sensitivity photoreceptor drum 15, thus the toner pickup amount at the developing is made constant and the toner density of image made constant. |
