| 摘要 |
PURPOSE:To improve the stabilization of a focusing servo system to a disk defect by changing a focus offset voltage to a prescribed value while the defect is detected when the defect of the disk is detected. CONSTITUTION:A beam from an optical pickup 14 passes through the disk defect in a condition that the focusing servo is supplied, a beam reflecting light from a disk 12 is omitted and the RF signal of an RF detecting circuit 26 is omitted. A defect circuit 28 detects the disk defect and outputs a defect DF signal to an input terminal INDF of an offset canceling circuit 25. At the circuit 25, when the terminal INDF goes to an H, a transistor Q1 is turned on and an offset adjusting voltage VFO of a focus error detecting circuit 22 is made into a zero. Thus, the focus error FE signal output of the circuit 22 also goes to the zero and the output of the amplifier circuit 34 does not change. For this reason, while passing through the defect, a driving voltage just before the defect is inputted to a focus coil 16 and an objective lens does not move carelessly. |
