| 摘要 |
PURPOSE:To obtain a calibrating device of a surface potential meter characterized by high measuring accuracy and a simple structure, by providing the surface potential meter, which detects the potential on a electrostatic holding body, and making it possible to switch a conductor layer to the ground and a specified bias potential. CONSTITUTION:The normal copy mode keeps a switch S1 closed and a switch S2 turned to the grounding side. In this way, the surface potential of a light sensitive body 10 is detected with a potential sensor 13. The optimum developing bias is applied to a developing sleeve 17 from a developing electrode bias circuit 15 in correspondence with the detected value. Then development is performed. In a calibrating mode, a switch S1 is opened and the switch S2 is at first set to the grounding side. The potential of the light sensitive body 10 at this time is measured with the sensor 13. Calibration is performed at a zero point so that the output of a surface potential detecting circuit 14 becomes zero. Then, the switch S2 is set to the bias side. The potential of the light sensitive body 10 at this time is measured with the sensor 13. The gain is calibrated so that the output of the sensor 13 becomes the value corresponding to the bias potential. Since the calibration can be performed under the conditions, which are completely the same as the actual picture forming state from a mechanical viewpoint, high accuracy is obtained. |
