| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of a shift larger than actual fluctuation in the phase relationship between a main scan start signal and a sub-scan start signal by controlling a line sensor for scanning a document and a rotary polygon mirror for scanning an image carrier with a light beam. SOLUTION: An image writing timing control circuit 101 detects the falling of an ITOP signal from a phase regulation circuit 126 and begins writing with laser in synchronism with the rising of an n-th BD signal from a BD sensor 107 to irradiate a photosensitive drum 105 with an image signal, i.e., a laser modulation light. Since it is superposed on a laser light scan line formed on the photosensitive drum 105 in synchronism with the first main scan start signal for the first revolution of the photosensitive drum 105, the scan lines being formed every time when the photosensitive drum 105 turns are not shifted from each other.
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