JPS57113430A - Focus servo leading-device - Google Patents

Focus servo leading-device

Info

Publication number
JPS57113430A
JPS57113430A JP18866280A JP18866280A JPS57113430A JP S57113430 A JPS57113430 A JP S57113430A JP 18866280 A JP18866280 A JP 18866280A JP 18866280 A JP18866280 A JP 18866280A JP S57113430 A JPS57113430 A JP S57113430A
Authority
JP
Japan
Prior art keywords
focus servo
amplifier
signal
switch
closed
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.)
Granted
Application number
JP18866280A
Other languages
Japanese (ja)
Other versions
JPS6218972B2 (en
Inventor
Shunji Harikae
Tomio Yoshida
Akifumi Nakada
Michiyoshi Nagashima
Toshio Sato
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.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial 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 Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP18866280A priority Critical patent/JPS57113430A/en
Publication of JPS57113430A publication Critical patent/JPS57113430A/en
Publication of JPS6218972B2 publication Critical patent/JPS6218972B2/ja
Granted 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 lead in a focus servo stably and in safety, by approaching a diaphragm lens to a recording medium from a position distant from the recording medium and by closing the focus servo at the moment the circumference of a recording surface is irradiated with a fine spot. CONSTITUTION:An error signal when supplied to a terminal B is applied to a diaphragm lens driver 9 through an amplifier 20, a phase compensating circuit 21, a switch 22, and a driving circuit 23. With the switch 22 closed, a focus servo circuit is closed. The output of the amplifier 20, on the other hand, is compared with a reference voltage Vb by a comparator 26 through a differentiating circuit 25, thereby outputting a signal (c) which exceeds the Vb. The output signal of the amplifier 20 is further passed through an absolute-value amplifier 27 and an inverter 28 to output a signal (d) which has level 0 only at zero-cross points. The signals (c) and (d) are inputted to an AND gate 29 and an FF30 and the switch 22 is closed by its output signal (h) to lead in focus servo stably and in safety.
JP18866280A 1980-12-29 1980-12-29 Focus servo leading-device Granted JPS57113430A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP18866280A JPS57113430A (en) 1980-12-29 1980-12-29 Focus servo leading-device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP18866280A JPS57113430A (en) 1980-12-29 1980-12-29 Focus servo leading-device

Related Child Applications (1)

Application Number Title Priority Date Filing Date
JP20461586A Division JPS6297139A (en) 1986-08-29 1986-08-29 Focus servo pull-in device

Publications (2)

Publication Number Publication Date
JPS57113430A true JPS57113430A (en) 1982-07-14
JPS6218972B2 JPS6218972B2 (en) 1987-04-25

Family

ID=16227647

Family Applications (1)

Application Number Title Priority Date Filing Date
JP18866280A Granted JPS57113430A (en) 1980-12-29 1980-12-29 Focus servo leading-device

Country Status (1)

Country Link
JP (1) JPS57113430A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59116941A (en) * 1982-12-23 1984-07-06 Matsushita Electric Ind Co Ltd Recording surface detecting circuit
JPS6164621U (en) * 1984-09-29 1986-05-02
JPS61175936A (en) * 1985-01-29 1986-08-07 Nec Corp Focus servo-device in optical information recording device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5538639A (en) * 1978-09-07 1980-03-18 Pioneer Video Corp Servo drawing-in unit for focus lens of optical information reader
JPS574035U (en) * 1980-06-03 1982-01-09

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5386128A (en) * 1977-01-08 1978-07-29 Agency Of Ind Science & Technol Driving circuit for magnetic bubble

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5538639A (en) * 1978-09-07 1980-03-18 Pioneer Video Corp Servo drawing-in unit for focus lens of optical information reader
JPS574035U (en) * 1980-06-03 1982-01-09

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59116941A (en) * 1982-12-23 1984-07-06 Matsushita Electric Ind Co Ltd Recording surface detecting circuit
JPH0421931B2 (en) * 1982-12-23 1992-04-14 Matsushita Electric Ind Co Ltd
JPS6164621U (en) * 1984-09-29 1986-05-02
JPS61175936A (en) * 1985-01-29 1986-08-07 Nec Corp Focus servo-device in optical information recording device
JPH0519773B2 (en) * 1985-01-29 1993-03-17 Nippon Electric Co

Also Published As

Publication number Publication date
JPS6218972B2 (en) 1987-04-25

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