| 摘要 |
PURPOSE:To secure the proper tracking control by using the offset voltage detected by means of track searching to correct a tracking control signal. CONSTITUTION:An address signal is sent to a sequence control means to designate a track having the information to be reproduced or a track where the information is recorded. Then an optical pickup system is driven, and a light spot of this optical system performs a scan in the track crossing direction. As a result, a sine wave tracking control signal is produced at the output of a differential amplifier 22 and then applied to an offset voltage detecting circuit 34. The DC offset voltage is converted into the digital value by an A/D converter 35 and applied successively to a latch circuit 36. The output of the circuit 36 is converted into analog signals by a D/A converter 37 and applied to a subtractor 32. While the output of the amplifier 22 is applied to the subtracter 32 via a switch circuit SW1. The subtracter 32 subtracts the offset voltage value from the output of the amplifier 22. Thus the tracking control signal is corrected, and the output of the subtracter 32 is turned into a correct tracking control signal having the positive/negative symmetry. |
