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US 6,783,832 B2Granted
Information recording medium
AssigneeHitachi, Ltd.
InventorsToshimichi Shintani, Motoyasu Terao, Keikichi Andoo
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Abstract
A multilayered optical disk having n recording layers is designed in such a manner that the transmittance Ti of the ith layer from a light-incident side satisfies the relationship: ∏ i - l j - i T i 2 ≥ n - j + l n when the light is focused on a recording film of the jth layer. By doing so, the recording/reading property of a multilayered medium is improved.
Claims19
An information recording medium, comprising:
- a substrate;
- and
- n recording layers provided on the substrate for recording information (where n is an integer of 2 or more), the n recording layers including both a focus ith layer (where i is an integer equal to or larger than 1 and yet equal to or smaller than n−1) useable as a focusing target to access an ith recording layer of the n recording layers, and an other focus jth layer (where j is an integer that is equal to or larger than 2 while equal to or smaller than n, and not i) useable as a focusing target to access a jth recording layer of the n recording layers which is deeper in the substrate relative to a predetermined light-incident side of the substrate than the ith recording layer;
- wherein the focus ith layer is selectably-transmissive responsive to focusing;
- wherein whenever light is focused substantially on the other focus jth layer, a transmittance Tj of the focus ith layer is substantially transmissive satisfying the expression:
- ∏ i = 1 j - i T i 2 ≥ n - j + 1 n
- to allow the light to substantially pass therethrough to allow access to the jth recording layer;
- and
- wherein whenever light is focused substantially on the focus ith layer, the transmittance Tj of the focus ith layer changes so that the focus ith layer becomes more reflective to allow access to the ith recording layer.
6 more elements
An optical information recording medium, comprising:
- a substrate, a first recording film, and a second recording film in a sequence from a light-incident side, wherein a nonlinear film is provided between the substrate and the second recording film, the nonlinear film having reflectance higher than transmittance whenever light focuses thereon, while having transmittance higher than reflectance whenever the light does not focus thereon.
An information recording medium, comprising:
- a substrate;
- a plurality of recording layers, at least one recording layer of which has a focusing-responsive selectably-transmissive layer associated therewith;
- wherein whenever light is NOT focused substantially on the selectably-transmissive layer, the selectably-transmissive layer is substantially transmissive to allow the light to substantially pass therethrough to allow access to a recording layer other than the at least one recording layer;
- and
- wherein whenever light IS focused substantially on the selectably-transmissive layer, the transmittance of the selectably-transmissive layer changes so that the selectably-transmissive layer becomes more reflective to allow access to the at least one recording layer.
2 more elements
Dependencies are inferred from the claim text.