| 摘要 |
PROBLEM TO BE SOLVED: To prohibit unnecessary abnormal images from occurring by minimizing the influence of an output abnormality of a horizontal synchronization signal. SOLUTION: The optical writing system has an LD 11 emitting a beam of light, a polygon mirror 12 scanning the light beam over a photosensitive drum 110, a synchronization sensing section 109 which generates a horizonal synchronization signal by detecting the beam of light scanned by the polygon mirror 12, and a writing position control section 106 having the function of counting reference clock pulses in synchronization with the horizontal synchronization signal and clearing the value of the count made, starting from the input of the horizontal synchronization signal. The writing system sets a maximum value of the input timing of the horizontal synchronization signal in the main scanning direction, judges that a failure to input the horizontal synchronization signal at the time when the input timing reaches the maximum value represents an abnormal condition and turns off the LD 11 at the time when the value of the count reaches the prescribed value from the time of judgment about the abnormality. COPYRIGHT: (C)2008,JPO&INPIT
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