Method for generating a pixel synchronizing signal in a picture input

Abstract

A pixel synchronizing signal between a picture input scanning apparatus and a reproduction record scanning apparatus is generated by dividing frequency of a reference signal according to scanning speed in the main scanning direction into a plurality of slightly different frequencies from one another by a plurality of dividers, pairs of the frequencies are converted into heterodyne frequencies by at least a pair of phase synchronizing loop circuits coupled with the heterodyne frequencies of mutual output frequencies thereof, and frequencies of output signals of the phase synchronizing loop circuits of which feeding back signals are the heterodyne frequencies among the phase synchronizing loop circuits are divided to make them output frequencies. The apparatus for practicing the method comprises a reference pulse generating means for generating a pulse signal of which frequency is varied according to the scanning speed in the main scanning direction, at least a pair of frequency dividers converting their frequencies into two signals having slightly different frequencies, at least a pair of phase synchronizing loop circuits converting frequencies of output signals of the dividers, a frequency mixer for outputting heterodyne frequency to a feeding back frequency divider and a frequency divider for dividing frequency of an output signal of the phase synchronizing loop circuit to which the signal of heterodyne frequency is to be fed.