| 摘要 |
PURPOSE:To return a pickup to a track jump start position in a short time by providing a means which jumps the number of tracks equal to a counted value in a jump start direction and returns the pickup to a jump start position. CONSTITUTION:An envelope detection circuit 21 detects the envelope waveform of the output signal of the pickup 2, and a track jump detection part 22 detects the generation of the track jump, judging from that the changing amount of an envelope waveform signal RFS exceeds the prescribed level and that a tracking error signal TRE crosses the prescribed level. Whenever the operation jumps one track, one track jump pulse TJP is generated, and a tracking counter 23 counts the pulse TJP to monitor the number of jumped tracks. After a signal processing circuit 4 ends the track jump, it inputs the number of kick pulses equal to the counted value of the counter 23 to a pickup feed circuit 6, and returns the pickup 2 to the jump start position.
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