| 摘要 |
PROBLEM TO BE SOLVED: To enable imaging without causing a light source failure or great deterioration of the image quality even when a quantity of light of a part of light beams cannot be detected. SOLUTION: In an APC quantity of light control mode, a level of a driving amount control signal to be outputted to an LD array driving part 92 is controlled by an amplifier 120 and a sample hold circuit 122 to make a laser beam light intensity detection value (quantity of light signal) agree with a set value (quantity of light set signal). When the level of the driving amount control signal exceeds an upper limit of a driving amount control range by the reason that the laser beams do not enter a light intensity sensor, or the like, the control mode is switched to a forced control mode because outputs of a comparator 128 and an OR circuit 126 are changed over. Laser beams are forcibly turned to a predetermined quantity of light by outputting as the driving amount control signal, a forced driving amount set signal of a level corresponding to a median value of the driving amount control range via a mode change means 124. COPYRIGHT: (C)2003,JPO
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