JPS55125547A - Light detecting unit - Google Patents

Light detecting unit

Info

Publication number
JPS55125547A
JPS55125547A JP3278379A JP3278379A JPS55125547A JP S55125547 A JPS55125547 A JP S55125547A JP 3278379 A JP3278379 A JP 3278379A JP 3278379 A JP3278379 A JP 3278379A JP S55125547 A JPS55125547 A JP S55125547A
Authority
JP
Japan
Prior art keywords
light
focus
divided
information recording
light detector
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
JP3278379A
Other languages
Japanese (ja)
Inventor
Toru Nakamura
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 JP3278379A priority Critical patent/JPS55125547A/en
Publication of JPS55125547A publication Critical patent/JPS55125547A/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
    • G11B7/0908—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

Landscapes

  • Automatic Focus Adjustment (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

PURPOSE:To satisfactorily detect a focus distortion due to displacement of the information recording surface, by using a light detector whose light receiving surface has been divided concentric circles. CONSTITUTION:The light receiving surface of a light detector 5 is divided into two concnetric circles, when light has been received, each divided surface generates a signal output depending upon the quantity of irradiated light, and the diameter of projected light is discriminated according to the output difference. And in case the focus is matched on the information recording surface, the differential output is adjusted to zero by projecting regular light onto the light detector 5. Thus the focus status which is always satisfactory can be obtained by moving the condensing lens 2 in its axis direction in accordance with the differential output depending upon distortion of the focus.
JP3278379A 1979-03-19 1979-03-19 Light detecting unit Pending JPS55125547A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3278379A JPS55125547A (en) 1979-03-19 1979-03-19 Light detecting unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3278379A JPS55125547A (en) 1979-03-19 1979-03-19 Light detecting unit

Publications (1)

Publication Number Publication Date
JPS55125547A true JPS55125547A (en) 1980-09-27

Family

ID=12368442

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3278379A Pending JPS55125547A (en) 1979-03-19 1979-03-19 Light detecting unit

Country Status (1)

Country Link
JP (1) JPS55125547A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5945733U (en) * 1982-09-18 1984-03-27 オンキヨー株式会社 Optical pickup focus detection device
JPS59119545A (en) * 1982-12-27 1984-07-10 Fujitsu Ltd Out-of-focus detecting method
EP0130831A2 (en) * 1983-06-30 1985-01-09 Kabushiki Kaisha Toshiba Apparatus for detecting a focusing state of an optical system
US4633454A (en) * 1983-02-15 1986-12-30 Pioneer Electronic Corporation Optical information pickup apparatus
JPH0443525U (en) * 1990-08-17 1992-04-14

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5945733U (en) * 1982-09-18 1984-03-27 オンキヨー株式会社 Optical pickup focus detection device
JPS59119545A (en) * 1982-12-27 1984-07-10 Fujitsu Ltd Out-of-focus detecting method
US4633454A (en) * 1983-02-15 1986-12-30 Pioneer Electronic Corporation Optical information pickup apparatus
EP0130831A2 (en) * 1983-06-30 1985-01-09 Kabushiki Kaisha Toshiba Apparatus for detecting a focusing state of an optical system
JPH0443525U (en) * 1990-08-17 1992-04-14

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