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AssigneeTDK Corporation
InventorsMasaki Aoshima, Hiroyasu Inoue, Koji Mishima, Hideki Hirata, Hajime Utsunomiya
Estimating the term…
An optical recording medium includes a substrate, a protective layer, a first recording layer containing an element selected from a group consisting of Si, Ge, Sn, Mg, In, Zn, Bi and Al as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Cu as a primary component. When the optical recording medium is irradiated with a laser beam, the element contained in the first recording layer as a primary component and the element contained in the second recording layer as a primary component are mixed by the laser beam and a region whose reflection coefficient has been changed is formed, whereby information is recorded.
An optical recording medium comprising a substrate, a protective layer, a first recording layer containing an element selected from a group consisting of Si, Ge, Sn, Mg, In, Zn, Bi and Al as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Cu as a primary component.
A method for optically recording information in an optical recording medium comprising a substrate, a protective layer, a first recording layer containing an element selected from the group consisting of Si, Ge, Sn, Mg, In, Zn, Bi and Al as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Cu as a primary component, the method for optically recording information comprising the step of irradiating the first recording layer and the second recording layer with a laser beam having a predetermined power via one of the substrate and the protective layer, thereby forming a region where the element contained in the first recording layer as a primary component and the element contained in the second recording layer as a primary component are mixed.
Dependencies are inferred from the claim text.
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Of recording layers: comprising inorganic materials only, e.g. ablative layers
Information storage based on relative movement between record carrier and transducer
Term end not estimated
The present invention relates to an optical recording medium and a method for optically recording information in the optical recording medium and, particularly, to a write-once type optical recording medium which can be fabricated using materials that apply only light load to the environment and into which information can be recorded with high sensitivity and from which information can be reproduced with high sensitivity, and a method for optically recording information in the write-once type optical recording medium with high sensitivity.
A write-once type optical recording medium is constituted so that information can be written once in a recording layer thereof. Illustrative examples of the write-once type optical recording medium include the CD-R, DVD-R, photo-CD and the like.
Such write-once type optical recording media require improvement not only in ability to record large amounts of information at high speed, high density and high sensitivity, but also in ability to store recorded information for a long time as initially recorded information, i.e., without degradation. Increasing concern about global atmospheric problems further makes it necessary to fabricate the write-once type optical recording media with materials which apply minimal load to the environment.
FIG. 1 (a) is a schematic partially cutaway perspective view showing an optical recording medium which is a preferred embodiment of the present invention.
FIG. 1 (b) is a schematic enlarged cross-sectional view showing a section indicated by the symbol R in FIG. 1 (a).
FIG. 2 is a schematic enlarged cross-sectional view showing the section indicated by the symbol R in FIG. 1 after irradiation with a laser beam.
The above and other objects and features of the present invention will become apparent from the following description and the corresponding drawings.
As shown in FIG. 1 (b), an optical recording medium 1 which is a preferred embodiment of the present invention includes a substrate 40, a protective layer 30, and a first recording layer 11 and a second recording layer 12 formed between the substrate 40 and the protective layer 30. In addition, a first dielectric layer 21 is formed between the protective layer 30 and the first recording layer 11 and a second dielectric layer 22 is formed between the second recording layer 12 and the substrate 40.
The substrate 40 serves as a support for supporting the second dielectric layer 22, the second recording layer 12, the first recording layer 11, the first dielectric layer 21 and the protective layer 30. The material used to form the substrate 40 is not particularly limited insofar as the substrate 40 can serve as the support for the above-mentioned layers. The substrate 40 can be formed of glass, ceramic, resin or the like. Among these, resin is preferably used for forming the substrate 40 since resin can be easily shaped. Illustrative examples of resins suitable for forming the substrate 40 include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, polyethylene resin, polypropylene resin, silicone resin, fluoropolymers, acrylonitrile butadiene styrene resin, urethane resin and the like. Among these, polycarbonate resin is most preferably used for forming the substrate 40 from the viewpoint of easy processing, optical characteristics and the like.