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Optical pickup device

A technology of optical pick-up and laser, which is applied in the direction of beam source, optical detector, optical recording head, etc., can solve the problems of focusing servo and tracking servo, deterioration of detection signal, etc., and achieve the effect of simple structure and suppression of stray light

Inactive Publication Date: 2012-12-26
SANYO ELECTRIC CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, if unwanted reflected light (stray light) enters the photodetector from the recording layers above and below the target recording layer, the detection signal will deteriorate, which may adversely affect the focus servo and tracking servo.

Method used

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Embodiment Construction

[0036] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0037]

[0038] First, refer to Figure 1 to Figure 10 , to describe the technical principle applied in this embodiment. In addition, here, assume a case where laser light is irradiated to a recording medium in which a plurality of recording layers are arranged in a stacking direction. Hereinafter, among the plurality of recording layers, the recording layer on which the laser light converges is referred to as a "target recording layer".

[0039] figure 1 (a) is a diagram showing a converging state of signal light and stray light when laser light (signal light) reflected from a target recording layer enters an astigmatic element such as an anamorphic lens (anamorens) in a parallel light state. In addition, "stray light 1" is the laser light reflected from the recording layer located one layer behind the target recording layer when viewed from the laser incident sid...

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Abstract

An optical system of an optical pickup device includes an astigmatism element which imparts astigmatism to BD light reflected on BD and CD light reflected on CD, and a spectral element which disperses four light fluxes of BD light and four light fluxes of CD light by diffraction, the four light fluxes of BD light and the four light fluxes of CD light being obtained by dividing the BD light reflected on the BD and the CD light reflected on the CD by a first straight line parallel to a converging direction by the astigmatism element, and a second straight line perpendicular to the first straight line. A photodetector of the optical pickup device is provided with first and second sensor groups for respectively receiving the four light fluxes of BD light and the four light fluxes of CD light dispersed by the spectral element.

Description

technical field [0001] The present invention relates to an optical pickup device, and is particularly suitable for use when irradiating laser beams of different wavelengths to a recording medium in which a plurality of recording layers are stacked. Background technique [0002] In recent years, along with the increase in the capacity of optical discs, multi-layer recording layers are progressing. By including multiple recording layers in one optical disc, the data capacity of the optical disc can be significantly increased. When stacking recording layers, conventionally, two layers were generally used on one side, but recently, in order to further increase the capacity, it is also considered to arrange three or more recording layers on one side. Here, if the number of stacked recording layers is increased, the capacity of the optical disk can be increased. However, the pitch between recording layers becomes narrower, and signal degradation due to interlayer crosstalk incre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11B7/126G11B7/131
CPCG11B7/131G11B7/0912G11B2007/0006G11B7/13922G11B7/1353
Inventor 永富谦司
Owner SANYO ELECTRIC CO LTD