| 摘要 |
PURPOSE:To obtain a picture with invariably uniform density regardess of the sensitivity difference of a photoreceptor without requiring a light source which has more than necessary power, by varying the quantity of incident light according to the sensitivity characteristics of the photoreceptor and setting the quantity of light to an optimum value. CONSTITUTION:A picture signal 1 which turns on and off a laser beam is inputted to a laser driving circuit 2 to drive a semiconductor laser device 3, projecting the laser beam corresponding to the picture signal upon the photoreceptor. The sensitivity characteristics of the photoreceptor 4 is highest in the beginning of use and then decrease gradually to a specific value, so a timer circuit 5 conforming with the characteristics is used to correct the quantity of light. A high- voltage on control signal is inputted to the timer circuit 5 to drive a timer. The output of the timer circuit 5 is inputted to a laser driving circuit 2 to control the quantity of light emitted from a laser device 3. |
