PROCESSING CIRCUIT OF LUMINANCE SIGNAL

摘要

PURPOSE:To improve both image resolution and sharpness by putting an LPF on an Y-shaped filter to delete the chrominance signal and therefore to secure satisfactorily the band of the luminance signal and at the same time using addition/subtraction type amplifiers which can be easily converted into ICs to constitute the circuits around a comb-shaped filter. CONSTITUTION:The signals supplied through an input terminal 21 are applied to a negative phase input terminal and a positive phase input terminal of a subtraction amplifier 22 via resistances R1 and R2 having approximately equal values to each other. A trap having a series connection of L1 and C1 is connected to the positive phase input terminal side. Then a signal equivalent to the output of an LPF15 is obtained at the positive phase input terminal of the amplifier 22; while a signal equivalent to the output of a BPF16 is obtained at the output terminal of the amplifier 22 since the input signal is applied directly to the negative phase input terminal of the amplifier 22 respectively. The signal is applied to the negative phase input terminal of a subtraction amplifier 25 through a 1H delay line 23, a Y-shaped/comb-shaped filter consisting of an addition amplifier 24 and a pass capacitor C2. Here the DC voltage equal to the terminal 21 is applied is applied via a voltage source E1 and a resistance R3. While the signal of the positive phase input terminal of the amplifier 22 is applied to the positive phase input terminal of the amplifier 25.