Abstract: An optical disk includes a first area on which user information is recorded, and a second area in which a plurality of marks radially extending are arranged in a track direction in the optical disk. Information about the reflectance of the optical disk is recorded in the second area. It is intended to optimize the amplification factor of the reproduced signal on the basis of the information about the reflectance of the optical disk in the second area. Control data and user data can be reproduced quickly and highly reliably without depending on the relationship between the reflectances of a recording area and a non-recorded area of the optical disk.

Abstract: An optical disk includes a first area on which user information is recorded, and a second area in which a plurality of marks radially extending are arranged in a track direction in the optical disk. Information about the reflectance of the optical disk is recorded in the second area. It is intended to optimize the amplification factor of the reproduced signal on the basis of the information about the reflectance of the optical disk in the second area. Control data and user data can be reproduced quickly and highly reliably without depending on the relationship between the reflectances of a recording area and a non-recorded area of the optical disk.

Abstract: An optical disk includes a first area on which user information is recorded, and a second area in which a plurality of marks radially extending are arranged in a track direction in the optical disk. Information about the reflectance of the optical disk is recorded in the second area. It is intended to optimize the amplification factor of the reproduced signal on the basis of the information about the reflectance of the optical disk in the second area. Control data and user data can be reproduced quickly and highly reliably without depending on the relationship between the reflectances of a recording area and a non-recorded area of the optical disk.

Abstract: An optical disk includes a recording region formed on a substrate for recording user data, and a management region formed on the substrate which includes an identification information region for recording disk-specific identification information such as address information (ID), a SYNC code, or an error detection code (EDC). The identification information region in this optical disk has a flat portion (a mirror region) formed by means of sectioning part of a groove or a land in a given step. The disk-specific identification information is recorded on the identification information region inclusive of this mirror region as irreversible record marks. Moreover, a signal of the disk-specific identification information is detected by a laser beam which is servoed on the recording track of this optical disk. Then, a change in the detected signal level of the disk-specific identification information is detected based on a predetermined threshold level.

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 of write once or rewritable type designed to have narrow tracks is provided, in which the wobble signal amplitude is scarcely fluctuated by crosstalk. The medium includes recording tracks formed in a spiral form and meandering at a predetermined wobble cycle T, and a plurality of zones constituting each of the recording tracks, each of the zones having a principal area formed to have a predetermined wobble phase. A relationship of T>80b holds between the wobble cycle T and a channel bit length b of recording data. The wobble phase of one of the recording tracks is adjusted so that an average phase difference d is d>?/2 between the wobble phase in the principal area in the zone and a wobble phase of an area in the recording track disposed adjacently on an inner circumferential side or an outer circumferential side of the principal area, in relation to all of the recording tracks disposed adjacently in the radial direction.

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 information recording medium and manufacturing method for high-speed and high density recording. An inorganic film is formed by sputtering while applying a bias voltage to shift the substrate voltage potential in the negative direction, or a laminated film is formed by applying energy after coating a substrate with an organic film, and the irregularities maintained even after the laminated film is formed, so that stable, high-capacity and high-speed recording can be attained by forming a multi-information-layer that still retains the irregularities.

Abstract: An optical disk recording and reproducing method. In a system for reproducing unique information which specifies a medium vendor and prohibits use by a third party in a control information area of an optical disk, this method reproduces the control information during a start-up period for recording or reproduction after the optical disk is loaded into a drive unit and displays the unique information on a display unit which is connected to the drive unit.

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: An optical disk includes a substrate which is formed with a plurality of grooves, and a recording layer which is provided on the substrate and which is formed of a phase-change material containing Bi, Ge, and Te. Each of the grooves is provided with a header section on which address information of the groove is recorded. The header section is formed by deflecting the grooves in the radial direction. The header sections of the respective grooves are arranged and aligned in the radial direction. Even when the address information of the predetermined groove was failed to be reproduced, the address information of the predetermined groove is specified from the address information of the adjoining groove. Accordingly, an optical disk is provided, which has a larger capacity, which has high reliability, and which is excellent in durability with respect to repeated writing of data information.

Abstract: An optical disk includes a first area on which user information is recorded, and a second area in which a plurality of marks radially extending are arranged in a track direction in the optical disk. Information about the reflectance of the optical disk is recorded in the second area. It is intended to optimize the amplification factor of the reproduced signal on the basis of the information about the reflectance of the optical disk in the second area. Control data and user data can be reproduced quickly and highly reliably without depending on the relationship between the reflectances of a recording area and a non-recorded area of the optical disk.

Abstract: A magneto-optical recording head comprises a magnetic coil formed on a lower surface of a transparent substrate opposed to a magneto-optical disk. A heat sink layer is provided at the outside of the magnetic coil on the lower surface. An objective lens is supported on an upper surface of the transparent substrate. The heat, which is generated by the magnetic coil, is released via the heat sink layer to the space between the magneto-optical disk and the substrate. The release of the heat is facilitated by the air stream which is generated by the rotation of the magneto-optical disk. The heat can be effectively released from the magnetic coil without inhibiting optical characteristics of the objective lens.

Abstract: In an optical disk for high density recording, for preventing the deformation of recording tracks caused by stress which may develop between the substrate and the recording stacked film formed thereon, a stress-compensation layer having a metal element such as Ti or Cr as a main component is provided. The stress-compensation layer undergoes contraction (tensile stress) to compensate for compression stress which develops in the stacked film during cooling after the thermal expansion of the substrate surface that occurs at the end of film formation. The stress-compensation layer has a pillar-like structure which, starting from the lower face, reaches the upper face of the film.

Abstract: A magneto-optical recording head comprises a magnetic coil formed on a lower surface of a transparent substrate opposed to a magneto-optical disk. A heat sink layer is provided at the outside of the magnetic coil on the lower surface. An objective lens is supported on an upper surface of the transparent substrate. The heat, which is generated by the magnetic coil, is released via the heat sink layer to the space between the magneto-optical disk and the substrate. The release of the heat is facilitated by the air stream which is generated by the rotation of the magneto-optical disk. The heat can be effectively released from the magnetic coil without inhibiting optical characteristics of the objective lens.

Abstract: An optical disk includes a recording region formed on a substrate for recording user data, and a management region formed on the substrate which includes an identification information region for recording disk-specific identification information such as address information (ID), a SYNC code, or an error detection code (EDC). The identification information region in this optical disk has a flat portion (a mirror region) formed by means of sectioning part of a groove or a land in a given step. The disk-specific identification information is recorded on the identification information region inclusive of this mirror region as irreversible record marks. Moreover, a signal of the disk-specific identification information is detected by a laser beam which is servoed on the recording track of this optical disk. Then, a change in the detected signal level of the disk-specific identification information is detected based on a predetermined threshold level.

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: A high-density information recording medium free from lowering the reflectance by over-write of a large number of times and exfoliation defect in a structure for suppressing cross-erase. This medium includes, over a substrate having a groove shape, a recording layer, and three-layered thin films of a first interference layer, a second interference layer and an interface layer having mutually different compositions and disposed on a laser beam incidence side of the recording layer in order named from the laser beam incidence side. The first interference layer has a smaller refractive index and a larger thermal conductivity than the second interference layer, the interface layer is interposed between the second interference layer and the recording layer, and a distance between the first interference layer and the recording layer is greater than at least a groove depth.

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.