Victor Company of Japan, Limited

Toshinori Kawanishi

Mikiya Kuroda

Makoto Itonaga

Kenji Oishi

Eiji Nakagawa

Koji Tsujita

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 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.

Optical recording medium and process for producing it

An optical disc-like recording medium has on one surface of its transparent substrate a ROM region where a plurality of pits are formed in correspondence with a predetermined information signal, and a RAM region where a plurality of guide grooves for tracking are formed and where an information signal is capable of being recorded. The optical disc-like recording medium transparent substrate is formed with a recording film made of an organic material and arranged to have a light-absorbing effect. Its refractive index is varied in response to illumination of laser light with a predetermined wavelength. Further formed on the recording film is a reflection film made of a metal which reflects light incident thereon. The physical depth of the pits is arranged to be equal to the physical depth of the guide grooves. The optical depths of the pit and guide groove have predetermined values which result from adjusting the thicknesses of the respective portions of the recording film present on the pit and guide groove. The width of the pits is preferable to be greater than the width of the guide grooves by a predetermined value. Optical disks interchangeable with compact disks are thus easily produced.

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Yokosuka, Japan

Toshinori Kawanishi