| 摘要 |
PURPOSE:To sufficiently compress disturbance and to improve the transfer rate of an optical disk by removing a false focus error signal mixed with disturbance outputted when an optical spot crosses a track by a focus leakage signal component formed from a tracking error signal and a sum signal by another circuit. CONSTITUTION:An objective value Rs indicating dispersion on the surface of an optical disk is sent to a transmission element 1 in a photoelectric conversion part through an adder 4a and an output from the element 1 is supplied to a transmission element 2 for executing focus operation and phase correction through an adder 4b. An output from the element 2 is supplied to a transmission element 3 in an objective lens actuator, and an output from the element is fed back to the adder 4a. In addition, a focus leakage signal component from a disturbance component forming block 6 including synchronizing detectors 7a, 7b and multipliers 8a, 8b is sent to the adder 4b through a switch 5 to offset disturbance Ws entering into the element 1. Thus, focus servo can be prevented from displacement and a servo band can be expanded.
|
