| 摘要 |
PURPOSE:To prevent the absence of both an image and a sound from continuing for a relatively long time after channel switching and power-on operation by resetting screen blanking a specific time after the input of a channel selection signal regardless of a complete tuning state and performing proper processing. CONSTITUTION:When channel selecting operation is performed, sound muting and screen blanking are started a slightly later. Then, AFT (automatic frequency adjusting) operation is started and when a complete tuning state is not obtained within 500ms, the screen blanking is reset 500ms after the start of the sound muting and screen blanking as shown in a figure B. The sound muting is reset at the time Te when the complete tuning state is obtained as shown by an alternate long and short dash line in the figure B. If the complete tuning state is not obtained even after a series of operations for WAFT (wide-range leading-in operation), the sound muting is reset at the point Tf of the completion of the series of operations.
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