| 摘要 |
PURPOSE:To prevent the variation of contrast even if the picture quarity of a TV picture is adjusted, by adding a signal obtained by interrupting DC of an output from a characteristic variable transversal filter to a signal obtained by delaying an input signal by a prescribed period. CONSTITUTION:An input signal is delayed by delay circuits 2, 3 having equal delay time, the input signal and outputs from the circuits 2, 3 are weighted by alpha0-alpha2 in weighting circuits 4-6, the outputs from the circuits 4-6 are added by an adder 7 to constitute the characteristic variable transversal filter TVF. The weighting forms alpha0+alpha1+alpha2=0 and alpha0-alpha2 are variables proportional to an analog controlling varialbe. The output of the adder 7 is interrupted at its DC component by a DC interrupting means DS consisiting of a characteristic fixing type TVF and the output signal is inputted to an adder 13. The output of the circuit 2 is delayed 12 by the operating time of the circuits 4-6, the adder 7 and the means DS and added to the output of the DS by an adder 13 to output the added signal. |
