EP0289352A2
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Optical recording medium and process for making an optical recording medium
Assignee: Yamamoto Chemicals Inc
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Filing: 1988-04-29
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Granted: —
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Expires: 2008-04-29
Abstract
Abstract An optical recording medium has a transparent substrate (100) having prepits and/or pregrooves for system control signals and first and second recording layers (200, 300) formed thereon in order, which layers individually have a specific reflectance, transmittance and absorbance. A laser beam is irradiated on the transparent substrate side of the medium to record or read out information by detecting the variation of the amount of light as a sum of the reflected light from the boundary between the first recording layer (200) and the substrate (100) and the reflected light from the boundary between the second recording layer (300) and air; the system control signals are primarily obtained from the prepits and/or pregrooves. The first recording layer contains an organic dye having a transmittance of 10 - 50% and an absorbance of 40% or more against the wavelength of a laser beam used for writing while the second recording layer contains an organic dye having an absorbance of 20% or less and a reflectance of 25% or more at the air boundary at the wavelength region of the laser beam. The optical recording medium can be made by a coating on coating process wherein the transparent substrate having prepits and/or pregrooves is coated using two dye solutions in series to form the first recording layer and the second recording layer. The two dye solutions are prepared using two organic dyes which are each soluble exclusively in either a low polar solvent or in a high polar solvent.
Inventors
- 👤 Hiroshi Sukawa
- 👤 Sumio Hirose
- 👤 Shigeru Takahara
- 👤 Tomoyoshi Sasakawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 06:34
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/242; G11B7/244; G11B7/246; G11B7/248; Y; Y10; Y10S; Y10S430/00; Y10S430/146
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
195 words
An optical recording medium composed of a transparent substrate having prepits and/or pregrooves for system control signals, a first recording layer formed thereon, and a second recording layer further formed thereon, wherein: (a) the first recording layer is a recording layer containing an organic dye having a transmittance of 10 - 50% and an absorbance of 40% or more at the wavelength of a laser beam used to write information; (b) the second recording layer is a recording layer containing an organic dye having an absorbance of 20% or less and a reflectance of 25% or more at the air boundary at the wavelength of the laser beam used to write and/or read out information; and (c) the laser beam being irradiated to the medium on the transparent substrate side to write and read out information, thereby the system control signals from the prepits and/or pregrooves being primarily obtained by detecting the variation of the amount of light as a sum of the reflected light from the boundary between the first recording layer and the substrate and the reflected light from the boundary between the second recording layer and the air layer in contact therewith.
Claim 2
Dependent Claim
195 words
An optical recording medium composed of a transparent substrate having prepits and/or pregrooves for system control signals, a first recording layer formed thereon, and a second recording layer further formed thereon, wherein: (a) the first recording layer is a recording layer containing an organic dye having a transmittance of 10 - 50% and an absorbance of 40% or more at the wavelength of a laser beam used to write information; (b) the second recording layer is a recording layer containing an organic dye having an absorbance of 20% or less and a reflectance of 25% or more at the air boundary at the wavelength of the laser beam used to write and/or read out information; and (c) the laser beam being irradiated to the medium on the transparent substrate side to write and read out information, thereby the system control signals from the prepits and/or pregrooves being primarily obtained by detecting the variation of the amount of light as a sum of the reflected light from the boundary between the first recording layer and the substrate and the reflected light from the boundary between the second recording layer and the air layer in contact therewith.
Claim 3
Dependent Claim
36 words
An optical recording medium according to claim 1, wherein the chief component of the organic dye used in the first recording layer is an azaanulene dye, and for example is a phthalocyanine dye and/or naphthalocyanine dye.
Claim 4
Dependent Claim
36 words
An optical recording medium according to claim 1 or claim 2, wherein the chief component of the organic dye used in the second recording layer is a polymethine dye, and for example is a cyanine dye.
Claim 5
Dependent Claim
27 words
An optical recording medium according to claim 3, wherein a cyanine dye used in the second recording layer has 5 carbon atoms in its main chain, -(CR=CR)₂-CR=.
Claim 6
Dependent Claim
42 words
An optical recording medium according to any of claims 1 to 4, wherein the thickness of the first recording layer is in the range of 30 - 200 nm and the thickness of the second recording layer is 200 nm or less.
Claim 7
Dependent Claim
33 words
An optical recording medium according to any of claims 1 to 5, wherein the depth of the prepits and pregrooves formed on the substrate is in the range of 50 - 200 nm.
Claim 8
Dependent Claim
116 words
A process for making an optical recording medium composed of a transparent substrate having prepits and/or pregrooves for system control signals, a first recording layer formed thereon, and a second recording layer further formed thereon, wherein the process comprises: (a) providing a transparent substrate having prepits and/or pregrooves for the system control signals; (b) preparing two kinds of solutions, one comprising a low-polar solvent(s) and organic dye(s) soluble only in low-polar solvents, the other comprising a high-polar solvent(s) and organic dye(s) soluble only in high-polar solvents, (c) applying the two kinds of dye solution to the transparent substrate in sequence to form the first recording layer and the second recording layer, thereby forming a bilayered structure.
Claim 9
Dependent Claim
116 words
A process for making an optical recording medium composed of a transparent substrate having prepits and/or pregrooves for system control signals, a first recording layer formed thereon, and a second recording layer further formed thereon, wherein the process comprises: (a) providing a transparent substrate having prepits and/or pregrooves for the system control signals; (b) preparing two kinds of solutions, one comprising a low-polar solvent(s) and organic dye(s) soluble only in low-polar solvents, the other comprising a high-polar solvent(s) and organic dye(s) soluble only in high-polar solvents, (c) applying the two kinds of dye solution to the transparent substrate in sequence to form the first recording layer and the second recording layer, thereby forming a bilayered structure.
Claim 10
Dependent Claim
86 words
A process according to claim 7, wherein the first recording layer is a recording layer containing an organic dye having a transmittance of 10 - 50% and an absorbance of 40% or more at the wavelength region of a laser beam used to write information, and the second recording layer is a recording layer containing an organic dye having an absorbance of 20% or less and a reflectance of 25% or more at the boundary to the air at the wavelength region of the laser beam.
Claim 11
Dependent Claim
37 words
A process according to claim 7 or claim 8, wherein the low-polar solvent has a dielectric constant of 4.5 or less at 20°C and the high-polar solvent has a dielectric constant of 12 or more at 20°C.
Claim 12
Dependent Claim
37 words
A process according to claim 7, 8 or 9, wherein the chief component of the organic dye used in the first recording layer is an azaanulene dye, and for example is a phthalocyanine dye and/or naphthalocyanine dye.
Claim 13
Dependent Claim
35 words
A process according to any of claims 7 to 10, wherein the chief component of the organic dye used in the second recording layer is a polymethine dye, and for example is a cyanine dye.
Claim 14
Dependent Claim
25 words
A process according to claim 11, wherein a cyanine dye used in the second recording layer has 5 carbon atoms in its main chain, -(CR=CR)₂-CR=.
References Cited (Backward Citations)
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