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Method for correcting influence of thickness unevenness of recording medium, information recording/reproducing apparatus using the same method and optical head unit

  • US 20060092780A1
  • Filed: 12/13/2005
  • Published: 05/04/2006
  • Est. Priority Date: 07/31/2001
  • Status: Active Grant
First Claim
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1. An optical head unit comprising:

  • a light source supplies light of a predetermined wavelength;

    an objective lens focus the light from said light source to the recording layer of the recording medium;

    an objective lens moving mechanism moves the objective lens in the optical axis direction and in the direction intersecting a guide groove and a signal mark string formed in said recording medium preliminarily;

    a defocus detecting system detects a defocus in said objective lens;

    a thickness unevenness detecting system detects a thickness unevenness in a transparent resin layer of the recording medium provided nearest said objective lens; and

    a thickness unevenness correcting mechanism changes a focusing characteristic of light impinging upon said objective lens from said light source based on a change in the thickness of said transparent resin layer of said recording medium detected by said thickness detecting system.

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