| 摘要 |
PURPOSE:To prevent the duplicated recording of signal, by stopping the supply of recording signal through the detection of the effect due to interference between the recording and recorded signals, when recording is started from non-recording part and the recorded light touches the recorded part. CONSTITUTION:The bits at the recorded part shown in b reduce the light transmission and the repetitive frequency does not have the correlativity with the recording signal shown in a. When the recording light modulated for the intensity with the recording signal is emitted on the bits, the light signal detected at the PIN diode 9 is modulated with the bits as shown in c. Accordingly, the rectangular waves shown in d and shaped with the limiter for the waveform and the recording signal inputted from the terminal I are inputted to the phase comparison unit 103. The output of the phase comparator 103 is detected with the level detector 105 through the integrator 104 and shaped, pulses are developed when the phase variation is taken place, REC FF101 is reset and the recording mode is cancelled to avoid duplicated recording. |
