COMPENSATOR OF VARIATION OF TIME AXIS

摘要

PURPOSE:To reduce satisfactorily the DC level variation of a video signal delivered from a delay element by connecting an adder to the output side of a variable delay element to detect the DC level variation and supplying the detected level variation to one side of the adder so as to reduce the DC level variation of the adder output. CONSTITUTION:A CCD1 serves as a variable delay element which controls the compensation of the time axis variation of an input signal (a) in response to the change of the clock frequency. The output of a voltage control oscillator VCO2 is impressed to the CCD1 in the form of a clock signal. The frequency of the clock signal is controlled by a control signal (b) for compensation of time axis variation. The DC level of the signal (a) varies as the clock frequency is changed. Therefore the reproduced video signal of the output signal of the CCD1 receives the variation of the DC level and is supplied to an input terminal of an adder 5. A signal which eliminates the DC level variation of the reproduced video signal is supplied to the other input terminal of the adder 5. Thus a negative feedback loop is formed to detect the DC level variation of the reproduced video signal including the remaining DC level variation, i.e. the output signal of the adder 5 through a DC level detector 3. Then the output signal is supplied to the other input terminal of the adder 5 through a phase compensator 4. Thus the DC level variation of the reproduced video signal is suppressed.