JPS57133525A - Automatic focusing system of optical information reader - Google Patents

Automatic focusing system of optical information reader

Info

Publication number
JPS57133525A
JPS57133525A JP1629281A JP1629281A JPS57133525A JP S57133525 A JPS57133525 A JP S57133525A JP 1629281 A JP1629281 A JP 1629281A JP 1629281 A JP1629281 A JP 1629281A JP S57133525 A JPS57133525 A JP S57133525A
Authority
JP
Japan
Prior art keywords
focus
automatic
lens
control
disk
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
JP1629281A
Other languages
Japanese (ja)
Inventor
Kenji Kimura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Olympus Corp
Original Assignee
Olympus Corp
Olympus Optical Co Ltd
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 Olympus Corp, Olympus Optical Co Ltd filed Critical Olympus Corp
Priority to JP1629281A priority Critical patent/JPS57133525A/en
Publication of JPS57133525A publication Critical patent/JPS57133525A/en
Pending legal-status Critical Current

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
    • G11B7/0945—Methods for initialising servos, start-up sequences

Landscapes

  • Automatic Focus Adjustment (AREA)
  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)

Abstract

PURPOSE:To obtain an optimum in-focus position although plural stable points exist in a loop system of the automatic focus control using the focus error signal, by performing an automatic focus control by making use of the fact that the reproduced information signal is detected only at the area close to the in- focus position. CONSTITUTION:A selection switch 41 is connected to an OFF side terminal 41B before the automatic control starts for an objective lens 13, and a switching element 32 is connected to an OFF side terminal 32B. As a result, the lens 13 is shifted further away from a disk 14 to be held there. When the automatic control starts, the switch 41 is connected to a terminal 41A. Thus the charging voltage of a capacitor 44 is supplied to a focusing mechanism 34, and as a result the lens 13 gets close to the disk 14. At the in-focus position, the servo locking is applid to a control loop using the focus error signal given from a differential amplifier 18 by the output of a level sensor 37. When no reproduced information signal is detected any more, the element 32 is connected to the terminal 32B. Thus the lens 13 is once returned to its original position and then gets close to the disk 14 to perform the automatic focus control.
JP1629281A 1981-02-07 1981-02-07 Automatic focusing system of optical information reader Pending JPS57133525A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP1629281A JPS57133525A (en) 1981-02-07 1981-02-07 Automatic focusing system of optical information reader

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1629281A JPS57133525A (en) 1981-02-07 1981-02-07 Automatic focusing system of optical information reader

Publications (1)

Publication Number Publication Date
JPS57133525A true JPS57133525A (en) 1982-08-18

Family

ID=11912464

Family Applications (1)

Application Number Title Priority Date Filing Date
JP1629281A Pending JPS57133525A (en) 1981-02-07 1981-02-07 Automatic focusing system of optical information reader

Country Status (1)

Country Link
JP (1) JPS57133525A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6148133A (en) * 1984-08-15 1986-03-08 Hitachi Ltd Optical disc device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53132308A (en) * 1977-04-22 1978-11-18 Sony Corp Focus controller of optical reproducer
JPS54128707A (en) * 1978-03-27 1979-10-05 Mca Disco Vision Focus servo device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53132308A (en) * 1977-04-22 1978-11-18 Sony Corp Focus controller of optical reproducer
JPS54128707A (en) * 1978-03-27 1979-10-05 Mca Disco Vision Focus servo device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6148133A (en) * 1984-08-15 1986-03-08 Hitachi Ltd Optical disc device

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