| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of malfunction caused by complication in control as well as in a system since conventionally a laser beam radiated to a photodetector 43 is controlled and dealt with by setting up a memory for recording modulations because the laser beam radiated to the photodetector 43 has to be modulated to a prescribed intensity, although a laser beam radiated to an image exposure region varies each time in the maximum output by an image density signal, input/output characteristic data, ratio data, etc. SOLUTION: By adding a means for making an amplification rate changeable for a detection signal from a photodetector 43, the amplification in a proper range is made possible regardless of the maximum value of a laser beam to be modulated, eliminating wrong detection due to insufficient light quantity. Consequently, there is no need of controlling the laser beam by setting up the memory, which relieves complication systemwise and controlwise. COPYRIGHT: (C)2006,JPO&NCIPI
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