| 摘要 |
PURPOSE:To eliminate unnaturality of video by detecting an average level of an output of an R-Y colr difference signal and allowing the average level signal to control the amplification factor of a chrominance subcarrier amplifier. CONSTITUTION:A block a is an amplifier section for the R-Y color difference signal including a transistor (TR) Q1, and the TRQ1 amplifies a bias voltage decided by a resistance R1 and an R-Y signal applied via a capacitor C1 and a resistance R3 and gives the result to a block B. The block B is an integration circuit comprising a resistance R6 and capacitors C3, C4 and forms an average value of an R-Y demodulated output and gives the result to a block C. The block C consists of an emitter follower TRQ2 and a resistance R7, a color saturation adjusting volume VR is connected between the emitter of the TRQ2 and ground, and its output is fed to the chrominance carrier amplifier circuit. The chrominance carrier amplifier is controlled that the amplification factor is increased when an output of the variable volume VR is increased and the amplification factor is decreased when the output of the VR is decreased. |
