| 摘要 |
PURPOSE:To correct a bit shift by detecting the phase difference between the pulse string of reproduced data and data transferring clock and controlling either of them according to this phase difference. CONSTITUTION:A laser beam from a laser diode 7 simultaneously scans the prepit string and the recording pit string of the data in a recording medium 2. The laser beam reflected in the medium 2 is divided into the two of a P deflecting part and a S deflecting part by a deflecting beam splitter 10 and respectively received by photodiodes 11a, 11b. The output signal of the diodes 11a, 11b is amplified 12a, 12b, thereafter, respectively subtracted and amplified and added and amplified in a subtraction amplifying circuit 14 and an addition amplifying circuit 13. Consequently,the output signal E of the circuit 13 goes to be a prepit part and the output signal D of the circuit 14 goes to a data pulse part. The signal E is supplied to a PLL circuit 16 to form the data transferring clock G. The signal D is supplied to a phase comparison circuit 17 to detect the phase difference between the clock G and control 18 the phase difference to zero by an error signal H. |
