| 摘要 |
PURPOSE:To simplify the channel changing-over operation of a character broadcasting at the time of receiving the TELETEXT by executing the resetting automatically when the condition that the communication of a video detecting signal from a video detecting circuit is stopped lasts for the constant time or above in the character decoder. CONSTITUTION:When a TELETEXT channel is changed over and operated by a commander 11, a muting signal is generated from a microcomputer 9 for selecting the station. Then, a capacitor C1 is charged instantaneously and a switching circuit S2 comes to be an off condition. When the off condition is designed to continue for 2.0sec and the condition that the time video detecting signal does not arrives beyond said seconds continues, a character decoder 3 is automatically reset. On the other hand, the muting signal is generated, the output signal is generated from a delaying circuit 10, then, the signal is inputted to a RGB interface 7 as a blanking signal, and therefore, the screen is vanished. Consequently, it can be confirmed that a channel changing-over command is received from a TELETEXT receiver.
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