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US 2007/0183275 A1Published application
Method for correcting influence of thickness unevenness of recording medium, information recording/reproducing apparatus using the same method and optical head unit
AssigneeKabushiki Kaisha Toshiba
InventorHideo Ando
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Abstract
An optical disk unit of this invention includes a defocus detecting system for detecting a defocus of an objective lens, a thickness unevenness detecting system for detecting a thickness unevenness of a transparent resin layer provided nearest the objective lens of a recording medium, and a thickness unevenness correcting mechanism for changing the focusing characteristic of light impinging upon the objective lens based on a change in the thickness of the transparent resin layer detected by the thickness detecting system.
Claims1
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.
4 more elements
Dependencies are inferred from the claim text.