Time base corrector for eliminating time base fluctuations in a composite video signal

A time base corrector, comprising writing clock generating means for generating a writing clock following time base fluctuation of an input composite video signal, and reading clock generating means for generating a reading clock based on a reference signal, means for coupling said input composite video signal to a memory for writing said input composite video signal in said memory in synchronism with said writing clock, and data stored in said memory being read from said memory in synchronism with said reading clock, wherein said writing clock generating means comprises:

• a voltage controlled oscillator;
• phase difference detecting means for detecting a phase difference between said input composite video signal and an output signal of said voltage controlled oscillator;
• means, receiving an output signal of said phase difference detecting means as a control input signal, for generating offset voltages having polarities opposite to each other and a level corresponding to a signal level of said control input signal at predetermined timings in a back porch and a front porch of said input composite video signal;
• and
• an adder using the outer signal of said phase difference detecting means as an augend input signal, for adding said offset voltages to said augend input signal, and using a resultant output signal as a control signal of said voltage controllled oscillator.