Optical information recording medium and optical information reproducing apparatus
First Claim
1. An optical information recording medium to which an recording operation or reproducing operation of information is carried out by irradiating a laser beam, comprising:
- two recording layers provided through a space layer, wherein an absolute value of a change of a film thickness of said space layer for every unit length in a circumferential direction is equal to or less than a predetermined value which is determined based on a wavelength of said laser beam, a refractive index of said space layer in said wavelength and one of a line velocity of said laser beam and the shortest pit length in a pit sequence recorded in each of said recording layers.
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Accused Products
Abstract
In an optical information recording medium to which a recording operation or reproducing operation of information is carried out by irradiating a laser beam, there are provided with two recording layers provided through a space layer. An absolute value of a change Δd of a film thickness of the space layer for every unit length in a circumferential direction is equal to or less than a predetermined value which is determined based on a wavelength of the laser beam, a refractive index of the space layer in the wavelength λ and one of a line velocity of the laser beam and the shortest pit length in a pit sequence recorded in each of the recording layers.
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Citations
16 Claims
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1. An optical information recording medium to which an recording operation or reproducing operation of information is carried out by irradiating a laser beam, comprising:
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two recording layers provided through a space layer, wherein an absolute value of a change of a film thickness of said space layer for every unit length in a circumferential direction is equal to or less than a predetermined value which is determined based on a wavelength of said laser beam, a refractive index of said space layer in said wavelength and one of a line velocity of said laser beam and the shortest pit length in a pit sequence recorded in each of said recording layers. - View Dependent Claims (2, 3, 4)
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5. An optical information recording medium to which an recording operation or reproducing operation of information is carried out by irradiating a laser beam, comprising:
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M recording layers (M is a natural number more than
2); and
(M−
1) space layers, each of which is provided between every adjacent two of said M recording layers,wherein an absolute value of a change of a film thickness of each of said (M−
1) space layers for every unit length in a circumferential direction is equal to or less than a predetermined value which is determined based on a wavelength of said laser beam, a refractive index of said (M−
1) space layers in said wavelength, and one of a line velocity of said laser beam and the shortest pit length in a pit sequence recorded in each of said recording layers. - View Dependent Claims (6, 7, 8, 9)
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10. An optical information recording medium to which an recording operation or reproducing operation of information is carried out by irradiating a laser beam, comprising:
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M recording layer (M is a natural number more than
2); and
(M−
1) space layers, each of which is provided between every adjacent two of said M recording layers,wherein when a film thickness of N-th one (1≦
N≦
M−
2) of said (M−
1) space layers from a laser incidence plane is dN, a film thickness of (N+1)-th one of said (M−
1) space layers is dN+1, and a difference in the film thickness of the space layer is DS=|dN−
dN+1|, the absolute value of said change Δ
DS of said space film thickness difference DS for every unit length in a circumferential direction is equal to or less than a predetermined value. - View Dependent Claims (11, 12, 13, 14)
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15. An optical information reproducing apparatus which carries out reproduction of information by using the optical information recording medium, comprising:
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an optical head section configured to irradiate said laser beam to said optical information recording medium and to generate a reproduction signal from light reflected from said optical information recording medium;
an amplifier section configured to amplify said reproduction signal; and
a restraint means for restraining a change of said reproduction signal in a KHz band. - View Dependent Claims (16)
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Specification