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Improved reading/writing of information from multiple layer optical discs

A light point and optical technology, applied in information storage, recording information storage, head configuration/installation, etc.

Inactive Publication Date: 2009-05-20
KONINKLIJKE PHILIPS ELECTRONICS NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Obviously, the spot distance on the disc is too small to avoid overlap between the companion spot and this out-of-focus spot

Method used

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  • Improved reading/writing of information from multiple layer optical discs
  • Improved reading/writing of information from multiple layer optical discs
  • Improved reading/writing of information from multiple layer optical discs

Examples

Experimental program
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Embodiment Construction

[0057] To solve the y-error problem and the attendant CCT problem, a grating with a fine pitch such that the distance t between the main spot and the satellite spot on the disc is sufficiently large (well known in the field of optical storage for generating multiple bundles). Figure 11 The light spot at the photodetector is shown, with a distance of about 40 μm from the companion spot on the disk. The upper diagram corresponds to focusing on the L0 layer and the lower diagram corresponds to focusing on the L1 layer. The main spot and two companion spots are drawn, while the spot resulting from the reflection of the main spot is on another layer, the out-of-focus layer. Obviously, the spot distance on the disc is large enough to avoid overlap between the companion spot and this out-of-focus spot.

[0058] This has the following consequences. First, the field usage of the objective increases. The field angle is defined as the companion spot distance t divided by the objecti...

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PUM

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Abstract

A three-spots grating is proposed with a pitch resulting in large field use of the objective lens, typically about 2.3 deg. The field curvature related defocus and other aberrations makes the radial modulation zero, which solves the y-error problem. The resulting large spot distance on the disc, typically about 40 [mu]m, results in a spatial separation at the detector of the satellites and the spot reflected of the out-of-focus layer (for dual-layer disc readout), which solves the satellite coherent cross-talk problem.

Description

technical field [0001] The present invention generally relates to a method for writing / reading information to / from an optical storage disc, and a disc drive for performing such a method; hereinafter such a disc drive is also denoted "disk drive". [0002] The present invention more particularly relates to a method for writing / reading information from a multi-data layer disc, such as a dual-layer disc, and a disc drive for performing such a method. A dual-layer disc drive comprising a lens system comprising at least one lens for focusing light individually on at least one data layer of the disc and an actuator for moving at least radially of the disc The lens system. Background technique [0003] As is well known, an optical storage disc comprises at least one track of a storage space in the form of either a continuous spiral or a plurality of concentric circles, and information can be stored in the storage space in the form of a data pattern. Optical discs may be of the re...

Claims

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Application Information

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IPC IPC(8): G11B7/09G11B7/00
CPCG11B7/0903G11B2007/0013
Inventor S·斯塔林加
Owner KONINKLIJKE PHILIPS ELECTRONICS NV
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