Optical recording medium having servo area and groove section
AssigneeCanon Kabushiki Kaisha
InventorsOsamu Koyama, Koichiro Nishikawa, Eiji Ueda, Yasumori Hino
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Abstract
The present invention provides an optical recording medium capable of detecting groove start signals and groove end signals with an inexpensive detection circuit and allowing quick, stable clock detection and tracking pull-in, which optical recording medium is constructed in such a way that the depth DG of the grooves satisfies DG/(λ/N)<0.16, where λ is a wavelength of a light beam and N is an index of refraction of a substrate, and that the distance Ls between the groove edge and the pit closest thereto satisfies Ls>1.2 FWHM, where FWHM is a full width at half maximum of the light beam in the track direction.
Claims15
An optical recording medium for reproducing information using a light beam, comprising:
- a disk-shaped transparent substrate;
- servo areas and data areas formed on said substrate;
- and
- pits formed on said servo areas,
- wherein said servo areas are formed on flat sections of said substrate, said data areas are formed in grooves of said substrate, said servo areas and data areas are provided alternately in the circumferential direction of said substrate to thereby form information tracks,
- wherein a depth DG of said grooves satisfies an expression of DG/(λ/N)<0.16, where λ is a wavelength of the light beam and N is an index of refraction of said substrate, and
- wherein a distance Ls between an edge of said groove and a pit closest thereto satisfies an expression of Ls>1.2 FWHM, where FWHM is a full width at half maximum of said light beam in the track direction.
Dependencies are inferred from the claim text.