| 摘要 |
PURPOSE:To prevent picture quality from deteriorating by providing a means which determines the transmission timing of an image signal. CONSTITUTION:Beam detectors 2 and 3 which detect 1 laser beam and determine an image writing-out position on a photosensitive drum are arranged at a specific distance in the end direction of the drum. A host computer 4 sends a synchronizing signal VSYNC to a printer 1 in synchronism with a subscanning- directional synchronism request signal VSREQ from the printer 1 and count up to a specific number of horizontal synchronizing signals BD2 with a constant period outputted by the detector 2 scanning lines corresponding to raster scanning lines which can be scanned until the head raster scanning line scanned by a 1st laser reaches the scan start line position of the raster scanning lines in synchronism with the signal VSREQ, thereby sending out a signal VDO2 to the printer 1 when finishing counting up to the specific number of signals BD2. Consequently, deterioration in picture quality is precluded.
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