| 摘要 |
PROBLEM TO BE SOLVED: To automatically prevent the deviation of screen by controlling a switch such that a synchronizing signal or a composite video signal is not supplied to a digital comb-line filter in an external display mode but the signal is detoured directly to a synchronizing separator circuit. SOLUTION: An input terminal 100 includes a terminal 12 to receive a composite video signal of a television signal, a terminal 1 to receive a composite video signal or a synchronizing signal from an external device, input terminals 2a-2c to receive an RGB signal from the external device and an input terminal 3 to receive a high speed switch signal. An input detection circuit ANDs the high speed switch signal and a synchronizing signal from a synchronizing separator circuit and applies peak holding to the ANDed signal to obtain a control signal, which is used for switching control of a switch circuit 5. In the case of the external display mode, the switches SW1, SW2 are switched to connect each of terminals 2, 3. Thus, the composite video signal bypasses a digital comb-line filter and is fed to the synchronizing separator circuit and a video chroma processing circuit.
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