| 摘要 |
PURPOSE:To surely form a one-component toner thin layer in prescribed thickness on the surface of a developing roller, with a simple constitution. CONSTITUTION:A bias voltage is applied between a subroller 50 and the developing roller 40 so as to obtain a prescribed potential difference, by DC power sources 71 and 72, and electrostatically charged toner is supplied from the subroller 50 to the developing roller 40 based on the potential difference. The value of a current flowing in the subroller 50 is measured by an electrometer 81 and imparted to a control circuit 82, and the control circuit 82 controls the DC power source 72 so as to make the value of the current constant. When the value of the current is not made constant even by the control of the DC power source 72, a toner empty display unit 83 is operated. |
