| 摘要 |
PURPOSE:To obtain an accurate synchronizing signal by preventing erroneous operation due to noises, etc., by detecting reflected light from a mirror provided at the end part of a photoreceptor by two photodetectors and then by setting and resetting FF on the basis of the detection outputs. CONSTITUTION:At the scanning-start-side end part of electrophotographic photoreceptor 1, mirror 6 is arranged and with reflected beams from mirror 6, photodetectors 7a and 7b are irradiated continuously. Outputs of photodetectors 7a and 7b are binary-coded through comparators 8a and 8b and then sent to FF9 to set and reset FF. A picture signal, when FF9 is set, is sent to a laser synchronizing with the leading edge of the signal. In this case, if noises appear at elements 7a and 7b and a transmission system for their output signals, FF9 after element 7a is irradiated with the light is held reset until element 7b is irradiated with the light, so that its output Q will not be influenced by the noises. |
