| 摘要 |
PURPOSE:To prevent inferior print by detecting the abnormal quantity of irradiation rapidly by collating a pulse string, detected by reflecting the irradiation line of a light emitting element by a photoreceptor drum, with a pulse string of received data. CONSTITUTION:Data for one line are passed through shaft register 1 and buffer register 2 and light emitting elements 4 for one line are turned on selectively by driving circuit 3; and their light beams are projected upon drum 5 to form a latent image and also reflected to be photodetected by self-scanning image sensor 6. A signal having the level corresponding to the quantity of the light is outputted by sensor 6 in series and compared with a reference value by level comparator 7, which outputs a pulse string. The number of the pulses is found by out-counter 8 and compared by comparing circuit 10 with the number of pulses of received data obtained by in-counter 9. Thus, if light emitting element 4 fails to turn on or if the quantity of emitted light decreases, circuit 10 sends an alarm and the abnormal quantity of the irradiation is detected rapidly. |
