| 摘要 |
PURPOSE:To surely perform initial setting of focus no matter how a device may tilt by setting focus position after keeping the objective lens of an optical pickup away from the surface of a disk once when a power source is made on. CONSTITUTION:When a power source switch is closed, a capacitor C1 is charged once to negative side, and then charged to + side and supplied to a focus coil driving circuit 15. Current of reverse direction flows in a focus coil first, and a lens bobbin 2 is separated from a disk resisting restoring force of a damper 5, and the driven to get near to the disk slowly. When the objective lens is focused, pulses are generated from a zero cross detector 12 and supplied to the inversion FZC terminal of a control voltage generating circuit 13. At this moment the output voltage of the FCS terminal becomes zero, and the circuit 15 does not operate thereafter, and the focused state of the objective lens 4 is maintained. |
