| 摘要 |
PURPOSE:To start storing information from a prescribed track in the halfway position of a disc by storing a compensation scale number from the initial position of a scale to the detection of an innermost or outermost track and compensating a scale value corresponding to a prescribed track number with the compensation scale number when information is stored initially on the disc and moving a head to a position corresponding to this value. CONSTITUTION:A control circuit 54 allows a laser oscillator 42 to output a reproducing beam light; and when it is focused onto the innermost track, the reflected light from the track on an optical disc 19 is led to a photodetector 49, and respective output signals of photodetectors 491 and 492 are supplied to an adder 50 and a differential amplifier 51, and a signal corresponding to the sum of both outputs and a positional slippage signal corresponding to the difference between both signals are outputted. When an eccentric quantity detecting circuit 52 detects eccentricity, these signals are used as signals for direction and track. This eccentricity is stored in an address corresponding to signals of a reference position detector 36 and a position detector 35 in a storing circuit 53, and eccentricity compensation data is stored in the storing circuit 53 for each sector of the optical disc 19 divided to 32 sectors. |
