Focusing control method for optical disc

Abstract

The present invention is a focus control method of an optical disc, comprising the following steps: using a closed-loop servo system to control an optical head in a linear region of a focus error signal; providing n bias compensation voltages to be superimposed on the focus error signal , and obtain the corresponding n swing information state count values, wherein, each swing information state count value is superimposed on the focus error signal by using a bias compensation voltage, so that after the optical head moves a distance, a fixed The sampling frequency samples a wobble information within a fixed time and counts a decoded message to obtain the wobble information state count value; select the wobble information state count value with the largest value from the n wobble information state count values ​​and its corresponding A specific bias compensation voltage; and the specific bias compensation voltage is continuously superimposed on the focus error signal, so that the focus of the optical head can be stably focused on the reflective layer of the optical disc, and the quality of the optical drive signal is greatly improved.

Description

technical field [0001] The present invention relates to a focusing control method of an optical disc, and in particular relates to a method for correctly focusing the focal point of the laser beam emitted by the optical head on the reflective layer of the optical disc. Background technique [0002] Please refer to figure 1 , which shows the optical head reading system of the optical drive. Wherein, the laser diode 200 outputs a laser beam, and the beam passes through the collimating lens 205 , the polarized beam splitter 210 , the 1 / 4 wavelength plate 220 , and the collecting lens 225 to reach the optical disc 230 . The light beam reflected from the optical disk passes through the collecting lens 225 , the 1 / 4 wavelength plate 220 , the polarized beam splitter 210 , and the lens 240 , and is projected to the photodetector 250 . [0003] And because of the different types of optical discs, the distance between the reflective layer (Reflecting Layer) and the optical head rea...

AI Technical Summary

Problems solved by technology

[0012] However, due to the error of the closed-loop servo system itself, the position of the optical head of the known optical drive is not the optimal position when the focus error signal is zero.

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