Victor Company of Japan, Limited

Mikiya Kuroda

Toshinori Kawanishi

Kenji Oishi

Koji Tsujita

An optical disk is provided for recording data thereon as optically readable pits formed thereon and for reading data from the pits by means of a reproducing laser beam. The disk has a substrate of a light transmissive material. A reflective layer of a light reflective material is formed on one of the surfaces of the substrate. A light absorbing layer is formed on the other surface of the substrate on which the reproducing laser beam is projected. The light absorbing layer containing a coloring substance exhibiting light absorption characteristics that is small for the reproducing laser beam but large for a laser beam of a specific light wavelength band shifted from the reproducing laser beam wavelength band to a longer light wavelength side. The substrate may be of a colored substrate including the coloring substance. The light absorbing layer is not required in this case.

Optical disk

There is disclosed an optical recording medium for high density recording without degradation of reproducing output signals. The optical recording medium includes a transparent substrate made of resin having an information recorded portion on which optically readable information signals are recorded, a thermochromic layer provided over the transparent substrate, the thermochromic layer having a larger light transmittance when the thermochromic layer has a higher temperature than a threshold value by absorbing heat off a laser beam spot and the thermochromic layer having a smaller light transmittance when the thermochromic layer has a lower temperature than the threshold value by being cooled down, and a reflecting layer provided on the thermochromic layer, wherein a heat radiating layer made of transparent inorganic material is further provided in contact with the thermochromic layer so as to absorb heat generated in the thermochromic layer by being irradiated with the laser beam spot.

Optical recording medium

An optical recording medium for high density recording and reproducing has a transparent substrate formed with at least a series of information pits readable with a laser beam from an apparatus or formed with guide grooves for controlling operation of recording the information pits on the substrate and a masking layer provided on the transparent substrate for minimizing an effective spot diameter of the laser beam to pass through the masking layer. The masking layer has an optical transmittance reversely changeable corresponding to a change of temperature by being irradiated with the laser beam. The masking layer is made of a thermochromic material consisting of an electron donative color compound and an electron acceptant developer without polarized materials and is uniformly provided on the uneven transparent substrate formed with the information pits or the guide grooves by using a vacuum deposition method. As the electron acceptant developer, there are employed such organic materials as having electron acceptant developing function and decoloring function by a change of temperature.

Optical recording medium and the producing method of the optical

An optical recording medium comprising a substrate (1), a colorant recording layer (2) on and from which information is capable of being recorded and reproduced, provided on said substrate (1), an intermediate layer (3) provided on said colorant recording layer (2), said intermediate layer (3) comprising a material that is transparent to recording-reproducing light, has a lower refractive index than that of a colorant contained in said colorant recording layer (2) and is soluble to an aliphatic or alicyclic hydrocarbon solvent, and a metal reflective layer (4) provided on said intermediate layer (3). A useful process for producing such a optical recording medium is also disclosed.

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Yokohama, Japan

Mikiya Kuroda