JPS57167140A - Measuring device for eccentricity quantity of disc - Google Patents

Measuring device for eccentricity quantity of disc

Info

Publication number
JPS57167140A
JPS57167140A JP5073881A JP5073881A JPS57167140A JP S57167140 A JPS57167140 A JP S57167140A JP 5073881 A JP5073881 A JP 5073881A JP 5073881 A JP5073881 A JP 5073881A JP S57167140 A JPS57167140 A JP S57167140A
Authority
JP
Japan
Prior art keywords
disc
laser beam
beam spot
information
eccentricity
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
JP5073881A
Other languages
Japanese (ja)
Inventor
Masaru Kamimura
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.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric 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 Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP5073881A priority Critical patent/JPS57167140A/en
Publication of JPS57167140A publication Critical patent/JPS57167140A/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
    • G11B7/095—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 specially adapted for discs, e.g. for compensation of eccentricity or wobble
    • G11B7/0953—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 specially adapted for discs, e.g. for compensation of eccentricity or wobble to compensate for eccentricity of the disc or disc tracks

Landscapes

  • Length Measuring Devices By Optical Means (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Rotational Drive Of Disk (AREA)
  • Manufacturing Optical Record Carriers (AREA)

Abstract

PURPOSE:To detect the eccentricity, by fixing a pickup of an optical information reproducing device where a signal corresponding to each bit is reproduced and detecting the number of traversals of tracks by a laser beam spot during one rotation of a disc. CONSTITUTION:In case a pickup is not moved in the direction of the radius of a disc and only an auto-focusing device is operated to rotate the eccentric disc by a motor, a laser beam spot A is equivalently moved in the direction of an arrow B as shown in figure (a). The signal obtained from a preamplifier at this time is as shown in figure (b). The amplitude of the frequency modulation signal of a high frequency is reduced according as the laser beam spot goes further from an information track, and this amplitude becomes zero when the laser beam spot comes to the part between information tacks. Consequently, when the laser beam spot traverses once the part between information tracks, the envelope of the frequency modulation signal of a high frequency is reduced once. A number N of reductions of the envelope during one rotation of the disc is counted to quantify the eccentricity quantity of the disc.
JP5073881A 1981-04-03 1981-04-03 Measuring device for eccentricity quantity of disc Pending JPS57167140A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5073881A JPS57167140A (en) 1981-04-03 1981-04-03 Measuring device for eccentricity quantity of disc

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5073881A JPS57167140A (en) 1981-04-03 1981-04-03 Measuring device for eccentricity quantity of disc

Publications (1)

Publication Number Publication Date
JPS57167140A true JPS57167140A (en) 1982-10-14

Family

ID=12867174

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5073881A Pending JPS57167140A (en) 1981-04-03 1981-04-03 Measuring device for eccentricity quantity of disc

Country Status (1)

Country Link
JP (1) JPS57167140A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0082390A2 (en) * 1981-12-21 1983-06-29 Discovision Associates Method for detecting excentricity in a video disc and in a video disc player
FR2608790A1 (en) * 1986-12-18 1988-06-24 Yokogawa Electric Corp IMPROVED TEST DEVICE FOR OPTICAL DISCS

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0082390A2 (en) * 1981-12-21 1983-06-29 Discovision Associates Method for detecting excentricity in a video disc and in a video disc player
FR2608790A1 (en) * 1986-12-18 1988-06-24 Yokogawa Electric Corp IMPROVED TEST DEVICE FOR OPTICAL DISCS

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