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Focus control in a multiple-beam disc drive

A technology of optical disc drive and light beam, which is applied in the fields of writing/reading information to/from optical storage media, optical recording and optical reading, and can solve the impossible focusing conditions, multi-beam spots cannot be accurately positioned on a plane, Multi-focus conditions are difficult to achieve and other issues

Inactive Publication Date: 2007-06-20
KONINK PHILIPS ELECTRONICS NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this multi-focus condition is difficult to achieve, for example due to the fact that the plane of an optical disc is generally not perfectly flat, or the fact that, for example, the objective lens has field curvature such that the multi-beam spots cannot be precisely positioned in one plane. , or this focusing condition may not be possible

Method used

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  • Focus control in a multiple-beam disc drive
  • Focus control in a multiple-beam disc drive
  • Focus control in a multiple-beam disc drive

Examples

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Embodiment Construction

[0021] Figure 1 schematically shows an optical disc drive device 1 suitable for storing information on and reading information from an optical disc 2, typically a DVD or CD. The disk 2, the thickness of which is shown in an enlarged manner, has at least one storage layer 2A. In order to rotate the disk 2, the disk drive device 1 comprises a motor 4 fixed to a frame (not shown for clarity), which defines a rotation axis 5 .

[0022] The disc drive apparatus 1 also includes an optical system 30 for scanning the disc 2 with a light beam. More specifically, in the typical arrangement shown in FIG. 1 , the optical system 30 includes a beam generating device 31 , typically a laser, such as a laser diode, arranged to generate a beam 32 . In the following, the different parts of the light beam 32 following the light path 39 will be indicated by the letters a, b, c etc. added to the reference numeral 32 .

[0023] The light beam 32 reaches the disk 2 via the beam splitter 33 , the co...

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PUM

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Abstract

A method for controlling an optical disc drive apparatus (1) which comprises: light beam generating means (31) for generating a plurality of N optical beams (32(i)); means (33, 34, 37) for focussing said beams in respective focus spots (F(i)); at least one adjustable member (34) for axially displacing said focus spots; comprises the step of calculating an optimum setting (ZOPTIMUM) for the adjustable member (34), such that the out-of-focus condition for the optical system (30) as a whole is as small as possible. The position of the adjustable member (34) may be controlled to be substantially equal to the said optimum setting (ZOPTIMUM). Or, one specific beam is maintained in a focus condition, the beam having number m=mOPT selected according to mOPT =+- INTEGERSQUARE{(N-1) / (2v2 in case N is odd or mOPT = +- INTEGERROUND IN-(N-2) / 8) in case N is even.

Description

technical field [0001] The invention relates to the fields of optical recording and optical readout. More specifically, the invention relates to the field of writing / reading information to / from optical storage media. One known optical storage medium is the optical storage disc; therefore, the invention will be explained in connection with optical storage discs, but it should be expressly noted that the description is not to be construed as limiting since the invention is also applicable to other types of optical storage media. scope of the invention. Background technique [0002] As known to those skilled in the art, optical storage discs include storage spaces on which information is stored in the form of data patterns. Optical discs may be of the read-only type, in which information is recorded during manufacture which can only be read by the user. Optical storage discs can also be of the writable type, in which information can be stored by the user. [0003] In order ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/09G11B7/14G11B7/13
CPCG11B7/0917G11B7/131G11B7/0943G11B7/14G11B7/09
Inventor T·W·图克C·T·H·F·利登鲍姆A·M·范德利
Owner KONINK PHILIPS ELECTRONICS NV