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Optical disk apparatus and focusing method

An optical disc device and optical disc technology, which are applied in the directions of recording/reproducing, head configuration/installation, instruments, etc. by optical methods, and can solve problems such as inability to focus lead-in control.

Inactive Publication Date: 2008-06-11
HITACHI LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] However, in the above configuration, at the time of the initial focus pull-in before storing the surface vibration, since the relative velocity of the light beam and the optical disk is affected by the surface vibration, stable focus pull-in control cannot be performed.

Method used

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  • Optical disk apparatus and focusing method
  • Optical disk apparatus and focusing method
  • Optical disk apparatus and focusing method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] FIG. 1 is a diagram showing the configuration of an optical disc device according to a first embodiment.

[0027] In FIG. 1 , the beam emitted from the laser 2 becomes parallel light through a collimating lens 3 , and converges on the disc 1 through a beam splitter 4 , a quarter wavelength plate 5 , and an objective lens 6 . The reflected light from the disk 1 passes through the objective lens 6 to become parallel light, passes through the 1 / 4 wavelength plate 5, the beam splitter 4, and the cylindrical lens (Cylindrical Lens) 7, enters the photodetector 8, and converts it into an electrical signal.

[0028] The output of the photodetector 8 generates a focus error signal FE representing the focus deviation of the light beam focused on the disc 1 by the signal processing circuit 9 . The focus error signal FE is input to the focus control circuit 10, and phase compensation is performed in order to make the focus control system operate stably.

[0029] The focus error si...

Embodiment 2

[0037] Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 8 .

[0038] In FIG. 5, parts having the same functions as those in FIG. 1 are given the same reference numerals. 22 is a diffraction grating, which divides the light beam emitted from the laser 2 into 0-order light and ±1-order light. The 0th order light is mainly used for detection of recording and playback signals, and the ±1st order light is used to detect focus error together with the 0th order light. A method of detecting a focus error using the ±1st-order light and 0-order light is called a differential astigmatism method. In addition, the jump circuit 23 outputs a jump signal JMP for accelerating and decelerating the actuator 6 in the direction of the disk surface through a jump trigger signal JTRIG from the controller 12 .

[0039] FIG. 6 shows the waveform of the focus error signal FE when the objective lens 6 starts approaching from a position far enough away f...

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Abstract

The present invention relates to an optical disk device and a focus pull-in method for initial focus pull-in at a position slightly deviated from the disk surface or recording surface while the disk is stopped or rotated at a sufficiently low speed relative to the normal rotation speed , after the introduction, the surface vibration component is stored as the normal rotational speed of the disk. The stored surface vibration components are applied to the focus movement module and introduced to the information recording surface.

Description

technical field [0001] The present invention relates to an optical disc (Disk) device and a focus (Focus) lead-in method. Background technique [0002] As background art in this technical field, there is, for example, Japanese Patent Laid-Open No. 7-65382. In this publication, it is described that "the surface vibration value of the optical disc 5 is obtained from the output of the focus deviation detector 10, and stored in the surface vibration storage circuit 25. , change the moving speed of the converging (converging) lens (Lens) 4, so that the relative speed of the light beam (Beam) and the optical disc 5 is slow at the focus introduction point, and stable focus introduction is performed". [0003] The focus lead-in of the conventional optical disc device will be briefly described. [0004] The motor rotates a disc-shaped recording medium (hereinafter referred to as an optical disc) at a predetermined rotational speed, converges and irradiates a light beam radiated fro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/085G11B7/09
CPCG11B7/0945G11B7/08511
Inventor 铃木基之
Owner HITACHI LTD