Patent ID: 6121826
Filing Date: 2000-09-19
Classification: H04N

Abstract:
A comb filter comprising:an input select switch for selectively outputting either an externally supplied image signal or a test signal independent of the image signal;first and second delay circuits for delaying the output of the input select switch for mutually different amounts of time;a variable-gain amplifier for amplifying the output of the first or second delay circuit, the gain of the variable-gain amplifier being variable;an operation circuit for deriving a sum or difference of the outputs of the variable-gain amplifier and the first or second delay circuit, for which the variable-gain amplifier is not provided;a detector for detecting a difference between the output of the operation circuit and a predetermined reference signal and for controlling the gain of the variable-gain amplifier in accordance with the difference; andcontrol means for controlling the operations of the input select switch and the detector,wherein the control means makes the detector operate for a time interval during which the control means controls the input select switch to selectively output the test signal.