| 摘要 |
PURPOSE:To irradiate plural laser beams onto a photosensitive body with a desired quantity of light by operating a control circuit based on the signal of the quantity of received light of a laser beam photodetector arranged in a non-image area near the photosensitive body to control successively the quantity of emitted light of plural semiconductor lasers. CONSTITUTION:First, only a semiconductor laser 1 is lit by a changeover switch 25 and a switching timing controller 30, and the signal of the quantity of light of the semiconductor laser 1 received by a photodetector 11 is compared by a comparator 23 and a reference voltage generator 24, and a reference difference signal from the comparator 23 is outputted to an applied current recorder 26 for LD 1 to control driving of a driver 28 for LD 1, and the quantity of light of the semiconductor laser 1 is controlled. Next, only a semiconductor laser 2 is lit, and the photodetector 11 receives the quantity of light of the semiconductor laser 2, and the difference signal from the comparator 23 resulting from comparison in the reference voltage generator 24 is outputted to an applied current recorder 27 for LD 2 by the same procedures as the above to control driving of a driver 29 for LD 2, and the quantity of light of the semiconductor laser 2 is controlled.
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