| 摘要 |
PURPOSE:To prolong the life of a light source by turning off the light in a period from immediately after the completion of an effective scanning detected by the 1st and the 2nd photodetecting means to immediately before the start of an effective scan. CONSTITUTION:In the figure, 12 is a forward scanning line and 13 is a backward scanning line. A photodetector 7 detects the completion of an effective forward scan. After a galvanomirror is inverted, the photodetector 7 detects the start of a effective backward scan 13 and also measures the time (t) from the completion detector of the forward scan 12 to the start detection of the backward scan 13. Similarly, a photodetector 6 detects the completion of the effective backward scan 13 and then measures the time (t') up to the detection of the start of the forward scan 12 following said scan. Then, forward turn-off time and backward turn-off time are found from the (t) and (t') and a laser is turned off only for this time. |
