Abstract: According to one embodiment, in a storage medium, a ratio of a minimum value of an amplitude of a wobble detection signal to a track shift detection signal is set to be equal to or greater than a predetermined value.

Abstract: A write-once optical information recording medium is provided that is capable of realizing a high transfer rate and a method of recording and reproducing information on and from the optical information recording medium. The optical information recording medium is constructed by stacking a reflective layer 12, a first dielectric layer 13, a recording layer 14, a write-protect layer 15, a second dielectric layer 16 and a transparent cover layer 17 on a polycarbonate substrate 11. The recording layer 14 is made of a phase-change material, and the cover layer 17 is made of UV curing resin. The recording layer 14 is irradiated with a laser beam with a wavelength of 500 nm or less to change from a crystalline phase to an amorphous phase. The write-protect layer 15 prevents the recording layer 14 from changing back to the crystalline phase from the amorphous phase, formed by the phase change.

Abstract: An optical disc apparatus in this invention includes an offset control unit which selects a parameter in accordance with the type of optical disc, and executes signal processing (offset control) by using the selected parameter.

Abstract: An information recording medium includes a structure fabricated by successively depositing a first protective layer, a first interface layer, a recording layer, a second interface layer, a second protective layer, an absorptivity control layer and a thermal diffusion layer on a substrate which is placed on a laser-beam-incident side of the medium, in which the first interface layer and the second interface layer are formed so as to contain elements Bi, Sn, Pb, etc. having the effect of promoting the crystallization of the recording layer and the total content of the elements in the first interface layer is set lower than that in the second interface layer, thereby reducing playback signal deterioration after frequent rewriting.

Abstract: There are provided a mounting unit configured to selectively mount first and second optical disks in which characteristics of recording films are different from one another, and a discriminating unit configured to discriminate which of the first and second optical disks is mounted on the mounting unit based on a level of a reproduction signal which is obtained by reproducing innermost peripheral portion of the first or second optical disk mounted on the mounting unit.

Abstract: A write-once optical information recording medium is provided that is capable of realizing a high transfer rate and a method of recording and reproducing information on and from the optical information recording medium. The optical information recording medium is constructed by stacking a reflective layer 12, a first dielectric layer 13, a recording layer 14, a write-protect layer 15, a second dielectric layer 16 and a transparent cover layer 17 on a polycarbonate substrate 11. The recording layer 14 is made of a phase-change material, and the cover layer 17 is made of UV curing resin. The recording layer 14 is irradiated with a laser beam with a wavelength of 500 nm or less to change from a crystalline phase to an amorphous phase. The write-protect layer 15 prevents the recording layer 14 from changing back to the crystalline phase from the amorphous phase, formed by the phase change.

Abstract: An phase-change optical disk comprises a substrate, a first protective layer, a first thermostable layer, a recording layer, a second thermostable layer, a second protective layer, an absorptance control layer, and a heat-diffusing layer which are provided in this order from a side on which a laser beam comes thereinto, wherein a recording layer material has composition ratios which are within a range surrounded by composition points of B3 (Bi3, Ge46, Te51), C3 (Bi4, Ge46, Te50), D3 (Bi5, Ge46, Te49), D5 (Bi10, Ge42, Te48), C5 (Bi10, Ge41, Te49), and B5 (Bi7, Ge41, Te52) on a triangular composition diagram. Recrystallization is not caused even when information is recorded on an inner circumferential portion, a reproduced signal is scarcely deteriorated even when rewriting is performed multiple times, and any erasing residue of amorphous matters scarcely appears at an outer circumferential portion.

Abstract: An information recording medium includes a structure fabricated by successively depositing a first protective layer, a first interface layer, a recording layer, a second interface layer, a second protective layer, an absorptivity control layer and a thermal diffusion layer on a substrate which is placed on a laser-beam-incident side of the medium, in which the first interface layer and the second interface layer are formed so as to contain elements Bi, Sn, Pb, etc. having the effect of promoting the crystallization of the recording layer and the total content of the elements in the first interface layer is set lower than that in the second interface layer, thereby reducing playback signal deterioration after frequent rewriting.