HORIZONTAL SYNCHRONIZING CIRCUIT

PURPOSE:To obtain a normal deflecting output having no influence of a turbulence even when a composite synchronizing signal in which the phase and the frequency of a horizontal synchronizing signal component during a vertical synchronizing signal period is disturbed is inputted by holding the output state of a frequency comparator to a state immediately before a vertical synchronizing signal is inputted only during the vertical synchronizing signal. CONSTITUTION:An analog switch 25 is turned on and off by the vertical synchronizing signal (h) separated in a synchronizing separating circuit 13 and during the vertical synchronizing signal period, it is turned off. During the period when the analog switch 25 is turned off, the output voltage (n) of the analog switch 25 is held to a voltage charged in a capacitor 26 immediately before the switch 25 is turned off, the phase and the frequency of the composite synchronizing signal (g) are disturbed during the vertical synchronizing signal period, thereby, even if the output voltage (m) of the frequency comparison circuit 27 is fluctuated, the output voltage (q) of a low pass filter 24 is not changed. Namely, only a change in the output voltage (p) of a low pass filter, namely, the output of a phase comparator 14 is displayed on the output voltage thetaof an addition circuit 18 for controlling a voltage control oscillator 16.