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Method for generating a corrected error signal, and corresponding apparatus

A signal and output signal technology, applied in the field of error correction signals

Inactive Publication Date: 2008-04-09
THOMSON LICENSING SA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In practice, due to the small track pitch on optical recording media, there is also the effect of the reflection of the writing main beam on the area immediately next to the main track

Method used

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  • Method for generating a corrected error signal, and corresponding apparatus
  • Method for generating a corrected error signal, and corresponding apparatus
  • Method for generating a corrected error signal, and corresponding apparatus

Examples

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Embodiment Construction

[0047] As described above, the focus error signal generated according to the DFE method actually includes the actual focus error and track position dependent focus offset components. In order to generate an offset-compensated focus error signal DFE, the focus error signal CFE ("central focus") generated in a manner dependent on the reflected main beam is combined with the focus error signal generated in a manner dependent on the reflected sub beam OFE ("outer focus") is combined in a weighted manner as follows:

[0048] DFE=CFE+g*OFE (1)

[0049] In this case, in Figure 8 For the shown application of the photodetector configuration with three four-quadrant detectors 10-12, the following relation holds true for the CFE signal and the OFE signal:

[0050] CFE=H`*((A+C)-(B+D)) (2)

[0051] OFE=L`*((E+G)-(F+H))+R`*((I+K)-(J+L)) (3)

[0052] In this case, g represents the weighting factor, H` represents the reflection factor of the track scanned by the main beam, and L` and R`...

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Abstract

In order to obtain a corrected or compensated focus error signal (DFEN) or track error signal (DPPN), it is proposed to generate primary and secondary scanning beams incident on adjacent tracks of an optical recording medium (7) and to detect the primary and secondary scanning beams reflected from the optical recording medium in order to derive from them primary-beam and secondary-beam focus error signals (CFE, OFE) or primary-beam and secondary-beam track error signals (CPP, OPP), which are subsequently normalized in order to obtain the compensated focus error signal (DFEN) or track error signal (DPPN) from the normalized primary-beam and secondary-beam error signals (CFEN, OFEN; CPPN, OPPN) by means of weighted combinations. As a result of the normalization, the corrected or compensated focus error signal (DFEN) or track error signal (DPPN) is generated independently of the reflection properties of the respectively scanned track.

Description

technical field [0001] The invention relates to a method for generating an error correction signal, in particular an offset compensated focus error signal or track error signal, for reading from and / or writing to an optical recording medium The invention also relates to a device for reading from and / or writing to an optical recording medium. Background technique [0002] A widely used method for forming a focus error signal is the so-called astigmatic method. This method can be used if only one type of track is intended to be scanned or if there is little interaction between the scanned type of track area and the focus error signal. Optical storage media in which the information track is a concave and convex track have different For focus shift, the concave tracks are called "grooves" and the convex tracks are called "lands". Asymmetries in the track geometry (width ratio, side slope of the track edges) can be seen as the cause for this. [0003] The problems associated ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11B7/09G11B7/007G11B7/13
CPCG11B7/00718G11B7/094G11B7/0903G11B7/131G11B7/0908G11B7/0943G11B7/09
Inventor 克里斯琴·布克勒弗里德赫尔姆·朱克
Owner THOMSON LICENSING SA