| 摘要 |
PURPOSE:To reduce a discomfortable sound and to eliminate a malfunction by delaying and detecting and outputting a control signal inputted at the time of sound recording and reproducing, generating a time limit signal of a prescribed time width when the first signal is inputted, and making the control signal ineffective when the second signal is inputted to obstruct the signal from passing through a sound recording device. CONSTITUTION:When a sound recording control signal is inputted to a signal receiving circuit 31, it is detected after an operation delay time, and a receiving start signa and a receiving end signal are generated. A filter circuit 32 starts the interception of a signal in a voice band by swithcing internally a communicating circuit 12 connected usually to a sound recording device 20 by inputting the receiving start signal, and releases it again by inputting the receiving end signal. Sound recording of a control signal can be prevented for the most part. A time limiting circuit 33 generates a time limit signal from the time when the receiving start signal is inputted, and when the receiving end signal is not inputted within this time width, the control signal is effective, and a controlling device 20. At the time of reproducing, a part of the sound- recorded control signal is inputted to the signal receiving circuit 31, but the receiving end signal is inputted within the time width of the time limit signal, the control signal is ineffective, and no malfunction occurs.
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