JPS6434077A - Video signal reproducer - Google Patents

Abstract

PURPOSE:To obtain a reproducing image with few turbulence of an image even in a reproducing signal containing noise by being equipping means for maintaining an automatic frequency control circuit in a constant condition at the time of dropout of a synchronizing signal. CONSTITUTION:An inputted reproducing luminance signal 23 goes to be not normal, a normal reference phase signal is dropped out owing to a noise bar, etc., and, simultaneously, a dropout detecting pulse signal is inputted from an input terminal 5 to an integrator 6. By the integrating operation of the integrator 6, a pulse, whose width is equal to a reference phase signal dropout period, can be obtained. The pulse signal is amplified by a pulse amplifier 24 up to sufficient a level so as to operate a switch 7, the switch 7 is fallen at a terminal (b) side by the output of the pulse amplifier 24, and a direct current set at a proper value is impressed on AFC circuits 3 and 22 instead of the reference phase signal. Thus, an unnecessary generating frequency turbulence in VCOs 9 and 21, which is generated because of the noise, can be prevented, and a deviation from a normal generating frequency can be made small.