Charged coupled device time base corrector system
OwnerVirgil L. Loweinventor
Life of this patent
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Abstract
An improved charged coupled device time base corrector system to compensate for a change in the phase or frequency of input video signals, as occurs in the playback of a video tape recorder, by changing the nominal delay through the corrector, comprising, in combination, an input feedback circuit and an output feedback circuit. The input feedback circuit includes two cascaded infinite gain circuits, an infinite gain phase detector followed by an infinite gain voltage amplifier which gives an error voltage that controls the frequency of the voltage controlled oscillator (VCO) utilized to control the system delay. The output servo loop always adapts itself to the input error voltage. The VCO is thereby driven at a rate of change of its frequency proportional to the incoming error signal. .
Claims6
An analog video time base corrector system comprising:
- input circuit means for receiving a video signal including synchronization information from a source, said input circuit means having an output;
- analog delay line means coupled to said output of said input circuit means for delaying said video signal and said included synchronization information, said analog delay line means having first and second outputs;
- first feedback circuit means coupled to the first output of said analog delay line means for controlling the delay thereof in response to said delayed synchronization information contained in said delayed video signal, said first feedback circuit means including an infinite gain phase detector means coupled to the first output of said delay line means for comparing the delayed synchronization information contained in said delayed video signal with a reference synchronization signal to detect the phase error in said delayed synchronization information, said phase detector means producing an output signal which is coupled through an infinite gain voltage amplifier to an input of a voltage controlled clock generator means, said clock generator means supplying a clock signal to a clock input of said delay line means, said clock signal having a frequency proportional to the phase error of said delayed synchronization information;
- second feedback circuit means coupled to receive the output of said infinite gain voltage amplifier of said first feedback circuit means for supplying said reference synchronization signal to said first feedback circuit means, said second feedback circuit means including an adaptive time constant amplifier means coupled to receive the output of said infinite gain voltage amplifier for automatically controlling the response rate of said second feedback circuit means based upon the phase error of said synchronization information, said second feedback circuit means further including a first voltage controlled oscillator means coupled to receive the output of said adaptive amplifier means for generating said reference synchronization signal;
- and
- output circuit means coupled to the second output of said analog delay line means and coupled to receive said delayed synchronization information for interfacing the delayed output of said analog delay line means with circuitry external to said video time base corrector system;
- whereby said system acts to slowly correct small phase errors and to rapidly correct large phase errors in synchronization timing such that a stable output video signal is produced for a wide range of input synchronization errors.
Dependencies are inferred from the claim text.