Tracking control device and tracking control method

Abstract

A tracking control system for outputting a tracking control signal for an optical pickup including a plurality of light detecting sections each of which converts reflected light of a light beam applied to an optical disk into an electric signal, and outputs the signal, includes: a balance correction amount calculating section for obtaining, as a balance correction amount, a value by which a differential phase tracking error signal based on each output of the light detecting sections should be shifted in accordance with a direct-current component of a differential amplitude tracking error signal based on each output of the light detecting sections such that a direct-current component of the differential phase tracking error signal approaches a given reference potential; a balance changing section for shifting the differential phase tracking error signal in accordance with the balance correction amount; and a tracking control section for generating the tracking control signal in accordance with the differential phase tracking error signal after the shift.

Description

technical field [0001] The present invention relates to tracking control techniques usable in optical disk devices and the like. Background technique [0002] In an optical disc device, tracking control is performed to make a light beam track a track on an optical disc based on a tracking error signal. One of the methods is the phase difference method. When the center of the photodetector that converts the reflected light from the optical disc into an electrical signal is not on the optical axis of the lens that condenses the light beam (when the lens is displaced), the DC level of the phase difference tracking error signal ( DC component) will deviate from the reference value, or the amplitude of the phase difference tracking error signal will become smaller. [0003] A tracking control device that generates a phase difference tracking error signal without being affected by such a lens shift is disclosed, for example, in Japanese Patent Application Laid-Open No. 11-175989....

AI Technical Summary

Problems solved by technology

[0023] As described above, in the conventional tracking control device, if the individual variation in the aberration of the lens that condenses the light beam is large, it is not possible to sufficiently correct the DC characteristic generated in the phase difference tracking error signal. Potential shift of

[0024] In addition, in addition to the circuit that needs to add the phase difference tracking error signal and the differential tracking error signal, a circuit that multiplies the gain and can change the amplitude of the differential tracking error signal arbitrarily is required, so the cost higher

[0025] In addition, when the light beam passes through a defect existing on the optical disc, or when the seek operation of moving the light beam to an arbitrary track on the optical disc is completed and the tracking control is performed again, unnecessary tracking error signals may be mixed into the differential tracking error signal. These signal components will have a bad influence on the phase difference tracking error signal and make the tracking control unstable

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