JPS57120239A - Focus servomechanism of optical information reader - Google Patents

Focus servomechanism of optical information reader

Info

Publication number
JPS57120239A
JPS57120239A JP530381A JP530381A JPS57120239A JP S57120239 A JPS57120239 A JP S57120239A JP 530381 A JP530381 A JP 530381A JP 530381 A JP530381 A JP 530381A JP S57120239 A JPS57120239 A JP S57120239A
Authority
JP
Japan
Prior art keywords
focus lens
lens
focus
disk
switch
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
JP530381A
Other languages
Japanese (ja)
Inventor
Haruhisa Takiguchi
Yukio Kurata
Kaneki Matsui
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.)
Sharp Corp
Original Assignee
Sharp Corp
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 Sharp Corp filed Critical Sharp Corp
Priority to JP530381A priority Critical patent/JPS57120239A/en
Publication of JPS57120239A publication Critical patent/JPS57120239A/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

Abstract

PURPOSE:To prevent a focus lens from striking a disk surface by driving the lens so that when the lens approaches the disk surface too much, it separates from the disk surface. CONSTITUTION:A switch 10 is closed and a switch 11 is opened immediately after a circuit operates; and a signal from a lamp wave generator 7 is applied to an adder 13 and a focus lens approaches a disk recording surface gradually. When the focus lens passes through its focal point, i.e., a point F, the output K of a comparator 8 is inverted to a positive potential. The switch 11 is closed and an error detection signal serves as a focus-lens driving signal to attain normal servo operation. As the focus lens approaches the disk recording surface, the output G of a comparator 12 goes down to a negative potential and is applied to the adder 13, where it is added to the error detection signal to generate a large negative potential, thereby driving the focus lens so that it is forced to separate from the disk recording surface.
JP530381A 1981-01-17 1981-01-17 Focus servomechanism of optical information reader Pending JPS57120239A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP530381A JPS57120239A (en) 1981-01-17 1981-01-17 Focus servomechanism of optical information reader

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP530381A JPS57120239A (en) 1981-01-17 1981-01-17 Focus servomechanism of optical information reader

Publications (1)

Publication Number Publication Date
JPS57120239A true JPS57120239A (en) 1982-07-27

Family

ID=11607484

Family Applications (1)

Application Number Title Priority Date Filing Date
JP530381A Pending JPS57120239A (en) 1981-01-17 1981-01-17 Focus servomechanism of optical information reader

Country Status (1)

Country Link
JP (1) JPS57120239A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002089124A1 (en) * 2001-04-20 2002-11-07 Matsushita Electric Industrial Co., Ltd. Optical disc apparatus

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5257803A (en) * 1975-10-31 1977-05-12 Thomson Brandt Optical reader
JPS533201A (en) * 1976-06-29 1978-01-12 Victor Co Of Japan Ltd Forcus servo system for light beam

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5257803A (en) * 1975-10-31 1977-05-12 Thomson Brandt Optical reader
JPS533201A (en) * 1976-06-29 1978-01-12 Victor Co Of Japan Ltd Forcus servo system for light beam

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002089124A1 (en) * 2001-04-20 2002-11-07 Matsushita Electric Industrial Co., Ltd. Optical disc apparatus
US7257053B2 (en) 2001-04-20 2007-08-14 Matsushita Electric Industrial Co., Ltd. Optical disc apparatus

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