Colour television signal processing circuit with a colour suppression detector

摘要

In the signal processing circuit according to the invention, direct-voltage control signals dependent on automatic colour control or ACC voltages are fed into a colour signal amplifier (30) to which recording and replay colour signals are (also) applied in order to control the operation of the colour signal amplifier (30) in accordance with the recording or replay mode. This control is effected by using a colour suppression signal which depends on mode-switching and ACC detector signals which are used for allocating the colour signal amplifier (30) for recording or replay mode. In both modes, colour signals are obtained at the output terminal of the colour signal amplifier (30). In the recording mode, unwanted recording colour signals appearing at the output terminal of the colour signal amplifier are essentially filtered out or bypassed by a low-pass filter (31) and only the ACC detector voltages used as colour suppression signals are supplied to a mixing circuit (16) which mixes brightness (contrast) signals (Y) and colour signals (C) with one another in order to supply mixed colour signals to be recorded. If necessary, this recording signal mixing circuit (16) prevents converted low-frequency colour signals from being supplied from the mixing circuit (16) to a magnetic recording head (H1) as determined by colour suppression signals. In the replay mode, the colour signals appearing at the output terminal of the colour signal amplifier are supplied to a replay mixer which assembles the mixed colour signals to be replayed from the brightness and colour signals to be replayed. In the recording mode, the input signals of the colour signal amplifier (30) are treated or processed in such a manner that colour suppression voltages are superimposed on the essentially unwanted recording colour signals in order to extract or filter out only the colour suppression voltages at the output terminal end of the colour amplifier, so that the circuit, which operates as colour amplifier in the replay mode, can (also) operate as circuit for treating or processing colour suppression signals in the recording mode, or the single circuit can operate differently in replay and in recording mode.