HK68795A - Automatic focussing control - Google Patents

Automatic focussing control

Info

Publication number
HK68795A
HK68795A HK68795A HK68795A HK68795A HK 68795 A HK68795 A HK 68795A HK 68795 A HK68795 A HK 68795A HK 68795 A HK68795 A HK 68795A HK 68795 A HK68795 A HK 68795A
Authority
HK
Hong Kong
Prior art keywords
focussing
recording medium
control loop
automatic focussing
focussing control
Prior art date
Application number
HK68795A
Inventor
Friedheim Zucker
Christian Buechler
Heinz-Joerg Schroeder
Original Assignee
Thomson Brandt Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson Brandt Gmbh filed Critical Thomson Brandt Gmbh
Publication of HK68795A publication Critical patent/HK68795A/en

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0908—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only
    • G11B7/0909—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only by astigmatic methods
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/094—Methods and circuits for servo offset compensation

Abstract

The invention concerns an optical scanning device which scans the frequency-warbled data tracks of a recording medium, the scanning light beam being reflected from the recording medium on to a four-quadrant photodetector (PD) with four photodiodes (A, B, C, D). In order to be able to compensate automatically for offset voltages produced in the focussing-control loop by, for instance, temperature fluctuations, the focussing signal and the track error signal are input into a multiplier circuit (M). The multiplier output is fed through a low-pass filter (TP) and as a compensation voltage to the focussing-control loop.
HK68795A 1989-10-28 1995-05-04 Automatic focussing control HK68795A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3936032A DE3936032A1 (en) 1989-10-28 1989-10-28 FOCUS CONTROL
PCT/EP1990/001603 WO1991006949A1 (en) 1989-10-28 1990-09-21 Automatic focussing control

Publications (1)

Publication Number Publication Date
HK68795A true HK68795A (en) 1995-05-12

Family

ID=6392483

Family Applications (1)

Application Number Title Priority Date Filing Date
HK68795A HK68795A (en) 1989-10-28 1995-05-04 Automatic focussing control

Country Status (14)

Country Link
EP (1) EP0500547B1 (en)
JP (1) JP2930715B2 (en)
KR (1) KR100251289B1 (en)
CN (1) CN1022518C (en)
AT (1) ATE114381T1 (en)
AU (1) AU6405190A (en)
DE (2) DE3936032A1 (en)
ES (1) ES2064763T3 (en)
FI (1) FI921879A (en)
HK (1) HK68795A (en)
HU (1) HU208588B (en)
MY (1) MY107278A (en)
TR (1) TR24658A (en)
WO (1) WO1991006949A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5978329A (en) * 1995-06-07 1999-11-02 Discovision Associates Technique for closed loop servo operation in optical disc tracking control
US20040213115A1 (en) * 2001-05-11 2004-10-28 Hideki Nakata Optical head, disc recording/reproducing apparatus, and objective lens drive method
DE102005018461A1 (en) * 2005-04-20 2006-10-26 Deutsche Thomson-Brandt Gmbh Focus control for optical scanner

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6070923U (en) * 1983-10-19 1985-05-20 パイオニア株式会社 Focus error detection device
JPS61269241A (en) * 1985-05-24 1986-11-28 Sony Corp Focus detecting device for optical head

Also Published As

Publication number Publication date
KR920704282A (en) 1992-12-19
CN1022518C (en) 1993-10-20
MY107278A (en) 1995-10-31
AU6405190A (en) 1991-05-31
CN1051444A (en) 1991-05-15
DE3936032A1 (en) 1991-05-02
FI921879A0 (en) 1992-04-27
KR100251289B1 (en) 2000-04-15
ES2064763T3 (en) 1995-02-01
JPH05501327A (en) 1993-03-11
EP0500547A1 (en) 1992-09-02
HU9201300D0 (en) 1992-07-28
HUT60874A (en) 1992-10-28
DE59007781D1 (en) 1995-01-05
WO1991006949A1 (en) 1991-05-16
EP0500547B1 (en) 1994-11-23
FI921879A (en) 1992-04-27
TR24658A (en) 1992-03-01
JP2930715B2 (en) 1999-08-03
ATE114381T1 (en) 1994-12-15
HU208588B (en) 1993-11-29

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Legal Events

Date Code Title Description
PC Patent ceased (i.e. patent has lapsed due to the failure to pay the renewal fee)