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Focusing control method for optical disc

A focus control, optical disc technology, applied in the direction of optical recording/reproduction, optical recording head, beam guiding device, etc., can solve the problem that the optical head is not optimal

Inactive Publication Date: 2006-01-04
LITE ON IT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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.

Method used

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  • Focusing control method for optical disc
  • Focusing control method for optical disc
  • Focusing control method for optical disc

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Embodiment Construction

[0028] Generally speaking, the spiral track on the reflective layer of the optical disc will record information of varying brightness and darkness, and the information will be focused on the photodetector through the reflected laser beam. The light intensity received by the light detection unit on the photodetector is summed and converted into an electrical signal to become a high-frequency signal (HF signal). After the optical drive decodes the high-frequency signal, the data recorded on the optical disc can be obtained. Generally speaking, the amplitude of the high-frequency signal is related to the focus of the optical head. For example, if the focus of the optical head is just on the reflective layer, the amplitude of the high-frequency signal will be the largest at this time, and the quality of the high-frequency signal It is also the best; on the contrary, if the focus of the optical head is not located on the reflective layer, the amplitude of the high-frequency signal a...

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Abstract

The optical disc focusing control method includes the following steps: controlling one optical head in the linear region of focusing error signal in one closed loop servo system; providing n offset compensating voltages superposed onto the focusing error signal to obtain n corresponding calculated values of swinging state information; selecting one out of the n corresponding calculated values of swinging state information and one specific corresponding offset compensating voltage; and superposing the specific offset compensating voltage onto the focusing error signal to make the focus of the optical head maintained on the reflecting layer of the optical disc and to raise the quality of optical disc driver signal greatly.

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...

Claims

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Application Information

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IPC IPC(8): G11B7/09G11B7/135G11B7/095
Inventor 徐正煜傅仁杰李敦介
Owner LITE ON IT
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