| 摘要 |
PURPOSE:To eliminate a recording modulated signal included in a pilot signal by matching the phase of a band-limited recording modulated signal and that of the recording modulated signal, which is included in the detection signal of the preliminarily recorded pilot signal, to each other and subjecting them to subtraction. CONSTITUTION:A signal to be recorded is generated in modulating circuits 9-1 and 9-2, and a modulated laser beam is irradiated on the surface of a disc. The reflected light is received by photodetectors M and N, and signals from detectors M and N are amplified by preamplifiers 4. Phases of modulated signals from circuits 9-1 and 9-2 are matched to those of outputs of amplifiers 4 through BPFs 10 by phase matching circuits 11, and they are subjected to subtraction by subtracting circuits 12. Outputs of circuits 12 are detected by detecting circuits 6 after passing BPFs 5. Level signals of tracking pilot signals corresponding to detectors M and N are supplied to a comparing circuit 7, and the comparison output is sent to a tracking control circuit 8. Thus, the recording modulated signal included in the pilot signal is eliminated. |
