In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

An optical recording medium includes a plurality of information signal layers, and at least one of the plurality of information signal layers other than the farthest information signal layer from a light irradiation surface includes: a recording layer; a first dielectric layer provided on a side opposite to a light incident side of the recording layer; and a second dielectric layer provided on the light incident side of the recording layer. The first dielectric layer and the second dielectric layer include indium oxide and tin oxide, and the atomic concentration of tin in the first dielectric layer is higher than the atomic concentration of tin in the second dielectric layer.

An information recording medium (10) including a first region (11) in which medium identification information has been recorded, a data region (13), and a second region (12) which is positioned between the first region (11) and the data region (13) and in which control information has been recorded, in which an area of the first region (11) is greater than an area of the second region (12) in size.

An information recording medium (10) including a first region (11) in which medium identification information has been recorded, a data region (13), and a second region (12) which is positioned between the first region (11) and the data region (13) and in which control information has been recorded, in which an area of the first region (11) is greater than an area of the second region (12) in size.

A reading method for reading contents information with a laser from an optical disc including a plurality of recording layers includes positioning a focus position of the laser at a first recording layer and reading a first part of the contents information recorded in the first recording layer. If a first link information recorded in the first recording layer is detected, judging whether a first condition is fulfilled or not. If the first condition is fulfilled, positioning the focus position of the laser at a second recording layer and reading a first link destination information recorded in the second recording layer. If the first condition is not fulfilled, reading a second part of the contents information recorded in the first recording layer.

The present invention relates to an information storage medium and a method for long-term storage of information.

The present invention relates to an information storage medium and a method for long-term storage of information.

An optical information storage medium includes a multilayer film that includes a plurality of extruded alternating active data storage layers and buffer layers, which separate the active data storage layers. The active data storage layers and buffer layers have thicknesses that allow the active data storage layers to be writable by non-linear or threshold writing processes to define data voxels within the active data storage layers that are readable by an optical reading device.

An optical recording medium includes a reflective layer, a first dielectric layer, a phase-change recording layer, and a second dielectric layer. The phase-change recording layer has an average composition represented by SbxInyMz, in which M is at least one of Mo, Ge, Mn, and Al, and x, y, and z are values in the ranges 0.70x0.92, 0.05y0.20, and 0.03z0.10, respectively, provided that x+y+z=1, the first dielectric layer includes a zirconium oxide-containing composite material or tantalum oxide, and the second dielectric layer includes a chromium oxide-containing composite material or silicon nitride.

A method is provided for judging whether a double-sided optical disc is placed reversely. Firstly, the disc is loaded. Then, a first optical pickup head emits a first laser beam to a first specified area of the disc and receives a first reflected laser beam. A second optical pickup head emits a second laser beam to a second specified area of the disc and receives a second reflected laser beam. If the first reflected laser beam generates an alternate brightness and darkness change and the second reflected laser beam does not generate the alternate brightness and darkness change, the disc is not placed reversely. If the first reflected laser beam does not generate the alternate brightness and darkness change and the second reflected laser beam generates the alternate brightness and darkness change, the disc is placed reversely.