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US 7,126,905 B2Granted
Information recording medium and information recording/reproducing apparatus to increase recording density
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTetsuo Saimi, Akihiro Arai, Tohru Nakamura
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Abstract
An information recording medium 101 includes: a transparent substrate 109 having a first surface A and a second surface B opposite to the first surface A; reflectance reduction means 110 provided on the first surface A of the transparent substrate 109; and an information recording layer 120 provided on the second surface B of the transparent substrate 109.
Claims9
An information recording medium comprising:
- a transparent substrate having a first surface and a second surface opposite to the first surface;
- reflectance reduction means provided on the first surface of the transparent substrate;
- and
- an information recording layer provided on the second surface of the transparent substrate,
- wherein portions of light having entered the first surface at an incident angle in the range of 0° to a maximum possible incident angle, which are transmitted through the transparent substrate, are used for recording information to the information recording layer or reproducing information recorded on the information recording layer,
- the reflectance reduction means reduces a reflectance for the light which enters the first surface at the maximum possible incident angle and is reflected by the first surface,
- the reflectance reduction means includes a transparent thin film layer,
- the thickness of the thin film layer is set so as to minimize the reflectance for light, which enters the first surface of the transparent substrate at the maximum possible incident angle and is reflected by the first surface of the transparent substrate, and
- the index of refraction of the thin film layer is smaller than that of the transparent substrate.
6 more elements
An information recording medium, comprising:
- a transparent substrate having a first surface and a second surface opposite to the first surface;
- reflectance reduction means provided on the first surface of the transparent substrate;
- and
- an information recording layer provided on the second surface of the transparent substrate,
- wherein portions of light having entered the first surface at an incident angle in the range of 0° to a maximum possible incident angle, which are transmitted through the transparent substrate, are used for recording information to the information recording layer or reproducing information recorded on the information recording layer,
- the reflectance reduction means reduces a reflectance for the light which enters the first surface at the maximum possible incident angle and is reflected by the first surface, and
- the light entering at the maximum possible incident angle has a prescribed wavelength λ and the reflectance reduction means includes a plurality of structures arranged on the second surface in a two-dimensional manner, each of the plurality of structures being substantially conical or pyramidal and having a dimension of λ/4 or more to 2λ or less along the first surface and a height of λ/2 or more to 3λ or less from the first surface.
4 more elements
Dependencies are inferred from the claim text.