Optical disk device

Abstract

Deterioration of an error rate due to disturbance of a reproduced signal is prevented by carrying out focus balance adjustment and tracking balance adjustment, with use of a focus control section for causing a focus servo to control the focus balance, based on a jitter value measured by a jitter measurement section, and a balance-adjusted TE signal generated by an error signal generating section, and a tracking control section for causing a tracking servo to control the tracking balance, based on an error center value measured by an error center measurement section and a balance-adjusted signal generated by an error signal generating section. Also, the focus servo carries out focus down-search thereby to switch on correctly the focus.

Description

technical field [0001] The invention relates to an optical disc device for balancing focus error signals and tracking error signals to perform defocus adjustment and off-track adjustment. [0002] The present invention also relates to an optical disc device for focusing a light beam radiated from an optical pickup onto a signal recording surface of the optical disc or the like using a return signal from the optical disc or the like. Background technique [0003] Recently, an objective lens having focal points at two positions in the optical axis direction (hereinafter referred to as a bifocal lens) is used to reproduce CD (Compact Disk), DVD (Digital Versatile Disk) by one optical disk reproducing apparatus. [0004] Generally, in an optical disk reproducing apparatus, defocus and off-track adjustments are automatically performed when the apparatus is started. Defocus adjustment is performed so that the light beam from the optical pickup is focused on the signal recording s...

AI Technical Summary

Problems solved by technology

Also, after passing through the damaged part, the offset voltage is applied to the error signal again, so that the servo mechanism system follows the error, so the driving voltage is disturbed

Due to the disturbance of the drive voltage, the signal reproduced from the optical disc is affected and its waveform is disturbed, making the error rate worse

[0009] The second problem occurs when there is a difference in the degree of damage at the position of the disc when the defocus adjustment and off-track adjustment are performed automatically and at the position of the disc when the disc is reproduced

then the disc will be damaged

In addition, since the focal length of the bifocal lens is short due to the characteristics of the lens, it is difficult to provide a mechanical stopper in the design to prevent collision between the disc and the objective lens in consideration of surface blurring during disc rotation

Images