| 摘要 |
PURPOSE:To prolong the life of a photosensitive body without a problem such as a decrease in image density by providing a detection means for detecting the number of times that the photosensitive body is used and a potential varying means for varying the potential of a conductive substrate in response to the output of the detection means. CONSTITUTION:When the number of copies is counted by a counter 22 after one copy is ended the output of the counter 22 is supplied to a microcomputer 18. In the microcomputer 18 voltage set data corresponding to the number of copies is extracted by referring to a table of the number of copies-voltage, and the data is applied to a bias power source 20, so that bias voltage from a bias power source 20 is controlled. And the bias voltage corresponding to the voltage data is applied to the conductive substrate 12. Light quantity set data corresponding to the number of copies is also extracted by referring to a table of the number of copies-light quantity, and applied to an AVR 24 as a power source for driving a light source 28, and the drive voltage of the light source 28, that is, its light quantity is adjusted according to the data. |
