Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
  • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
  • G11B7/258—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
  • G11B2007/24302—Metals or metalloids
  • G11B2007/24316—Metals or metalloids group 16 elements (i.e. chalcogenides, Se, Te)
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
  • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
  • G11B2007/25705—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials
  • G11B2007/25706—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of inorganic materials containing transition metal elements (Zn, Fe, Co, Ni, Pt)
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
  • G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
  • G11B7/2572—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers consisting essentially of organic materials

Definitions

• This invention relates to optical storage devices of the type comprising a rotatable disk having an active structure enabling variation of optical properties by means of focused write radiation, such as a laser beam, and reading data stored thereon by means of focused read radiation beam.
• focused write radiation such as a laser beam
• Tuned structures of the above type have a good signal to noise ratio, good sensitivity, and otherwise good performance. ; It has been found, however, that the recording medium may produce unstable reflectance upon exposure to various sources of heat. Such sources may include over- exposure, the heat of an ultraviolet lamp employed to cure the defocusing layer, and repeated exposure to the read beam, which may occur for
• optical storage device One form of optical storage device, in
• the surface of the substrate disk 10 conventionally has small imperfections, micro irregularities, tooling marks, polishing streaks, etc., which are undesirable for the optical properties of the recording media, and in order to remove these imperfections, a planarizing layer 11 is preferably provided on at least one surface of the substrate.
• the planarizing layer may have a thickness of for example 2 to 25 micrometers and may comprise an acrylic layer solvent coated by
• the surface of this layer should have a micro roughness less than 5 nanometers, and may be aluminized for this purpose.
• planar active layer also serves to prevent corrosion of the substrate, as well as to provide a chemical barrier between residual substrate contamination and the three layer structure of the phase layer, active layer and matrix layer described in the following paragraphs.
• the planarizing layer has been comprised of Rohm and Haas Acryloid A-10.
• This material is a solvent base methyl- methacrylate thermoplastic resin in a Cellosolve acetate having a viscosity of 800 to 1200 cps (Brookfield 25 degrees C), 30% plus or minus 1% percent solid, a density of 8.6 lbs. per gallon and a glass transition temperature of the polymer -8-
• the Acryloid A-10 resin was dissolved in a solution of Cellosolve acetate and butyl acetate with a final solvent ratio of 9:1, Cellosolve acetate to butyl acetate.
• the Cello ⁇ solve acetate was Urethane grade (boiling point of 156.2 degrees C), and the butyl acetate was spectral grade (boiling point of 126.5 degrees C).
• the butyl acetate may be substituted by Cellosolve acetate.
• the solution has a solid content of 22%, and a viscosity of 133 cps (Brookfield at 21 degrees C), filtered to 0.2 micrometers.
• the planarizing layer provides a base for the reflecting layer 12.
• the reflecting layer is preferably of aluminum, although copper or silver may be alternatively employed. A thickness of about 100 nanometers is preferred, although this dimension is not critical. It must be highly reflective at the read, write and coarse seek wavelengths employed, for example 633, 830 and 780 nanometers reflectively. The reflectivity should be equal to or greater than 0.85 in air, at these wavelengths.
• the reflective layer 12 is preferably formed by sputtering onto the planarizing layer, for example employing a Leybold-Heraeus in-line vacuum deposition system.
• the invention herein is not limited to the above structure wherein the reflective layer is formed on a planarizing layer, and other suitable tech ⁇ niques for forming a reflective surface of the required planarity, supported by the substrate, may be employed.
• the next three layers, defining a three- layer structure are comprised of a phase layer 13 on the reflective layer, an active layer 14 on the phase layer and a matrix layer 15 on the active layer.
• the phase layer and matrix layer may be of a plasma polymerized fluorocarbon with a fluorine to carbon atomic ratio of (for example only) 1.8.
• the active layer is preferably STC-68 tellurium alloy (Te 65 Se 2Q As.. Ni, Q ).
• a write beam for example a laser beam
• the optical energy of the beam is dissipated as thermal energy in the active layer, whereby the active layer agglomerates within the fluorocarbon phase and matrix layer.
• This agglomeration affects the optical transmittance of the three layer structure in accordance with the signal modulation of the write beam.
• the active layer absorbs energy to a different extent in the written and unwritten areas, to develop a reflective contrast.
• the active layer is a thin layer having discrete island-like globules.
• the layer therefore has irregular or discontinuous upper and lower surface characteristics defined by the globular surfaces.
• the mass equivalent average thickness of the active layer is thus about 7 to 8 nanometers.
• the globules denote discrete particles of dimension averaging within the range of 1 to 8 nanometers. It must be stable chemically, optically and in atomic structure. It has an amorphous lattice structure, with a glass transition temperature greater than 80 degrees C.
• the matrix " layer 15 may have a thickness of, for example, 270 nanometers.
• An adhesion layer 16 is provided on the matrix layer.
• the adhesion layer in addition to providing the proper surface energy for the
• the outer layer 17 of the structure is a defocussing layer, which serves to optically defocus dirt and dust particles and the like which have come to rest thereon.
• the defocusing effect prevents interference with the optical structures formed in the active layer, in writing and reading data, and in the optical seeking operations.
• the critical properties of the defocussing layer are that it be sufficiently thick to defocus dust particles that lay on the surface of the disk. In this sense, it is desirable that the layer be set to have, for example, a working thickness of about one millimeter, or one thousand nanometers.
• the layer is cured in ultraviolet light for a time less than 60 seconds, the curing being effective before removal of the coated disk from the deposition apparatus.
• the uniformity of exposure of the layer to ultraviolet curing light must be better than 90 percent, since uniformity is needed not just for an even cure, but also so that any change induced in the media is uniform.
• the intensity of the curing light at the disk surface must be 25 milliwatts per centimeter or greater, preferably with the spectral intensity
• An optical storage structure as above described in the form of a disk of about 14 inches diameter, is adapted to be rotated at a rate of for example, about 1300 rp .
• Writing of data on the disk is effected by a laser beam, at the write frequency, with a diameter of 0.5 plus or minus 0.05 nanometers, the beam having a write power equal to or less then 16 milliwatts.
• the reading photodetectors are adapted to read spot sizes of about 0.75 nanometers.
• a strip of nickel was overlayed on a larger sputtering target of the composition Te65, Se20, As5, so that the nickel and tellurium alloy were cosputtered by an argon ion beam by a secondary ion arrangement.
• a single target can be made as an intermixture or conglomerate of aluminum along with Te, Se and As, in a relatively homogeneous structure.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Optical Record Carriers And Manufacture Thereof (AREA)

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• 1985
  • 1985-07-03 WO PCT/US1985/001284 patent/WO1986000744A1/en not_active Ceased
  • 1985-07-03 EP EP85903608A patent/EP0189462A1/de not_active Withdrawn

Non-Patent Citations (1)

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