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Extended focus control

A technology of focusing elements and focal lengths, applied in the configuration/installation of heads, instruments, data recording, etc., which can solve the problem that the expansion of the focusing range is not accurate.

Inactive Publication Date: 2009-02-25
KONINK PHILIPS ELECTRONICS NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem with this known device is that two out-of-phase detector signals with periodic characteristics are required and the focus range extension of displacements outside the limited working range is not precise

Method used

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Examples

Experimental program
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Embodiment Construction

[0026] FIG. 1 a shows a disc-shaped record carrier 11 with a track 9 and a central hole 10 . Track 9 is a series of (to be) recorded positions representing information arranged in turns forming a spiral pattern of substantially parallel tracks on the information layer. The record carrier may be optically readable, called an optical disc, and have an information layer of the read-only or recordable type. Details on read-only DVD discs can be found in reference ECMA-267: 120mm DVD - Disc Read Only - (1997). Examples of recordable discs are CD-R and CD-RW and writable versions of DVD such as DVD +RW, and high-density writable discs using blue lasers, called Blue-ray Discs (BD). By providing optically detectable marks along the track (such as pits or crystalline or amorphous state mark), to represent the information on the information layer. A track 9 on a recordable type of record carrier is represented by a pre-embossed track structure provided during manufacture of the blank ...

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PUM

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Abstract

An apparatus for scanning a track on a record carrier has a head (41) for providing a beam of radiation and generating at least one sensor signal. The device has a focusing unit for controlling a focusing element to maintain an in-focus position for generating a focused spot on the track. The sensor signal is converted into a displacement signal by a multitude of piecewise converters (42, 43, 44), each converter converting a range of the sensor signal values into a position signal, and selection means (46) for selecting one of the position signals as the displacement signal based on an estimated displacement.

Description

technical field [0001] The invention relates to a device for scanning a track on a record carrier by means of a radiation beam, the track containing marks representing information, the device comprising a magnetic head for supplying the beam and generating at least one sensor signal, the magnetic head comprising: a focusing element a focusing unit for controlling the focusing element to maintain a focus point (in-focus) position, thereby generating a focused point on the track according to a displacement signal based on the sensor signal, the displacement signal representing the displacement of the focus element relative to the focus point position , the sensor signal has overlapping ranges of sensor signal values ​​for different ranges of displacement. [0002] The invention also relates to a method for scanning a track on a record carrier by means of a beam of radiation, the track containing marks representing information, the method comprising: generating at least one senso...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11B7/09G11B7/095
CPCG11B7/0946G11B7/0908G11B7/095G11B7/09
Inventor H·J·戈森斯F·C·彭宁
Owner KONINK PHILIPS ELECTRONICS NV