Abstract: Tracking control is carried out by a push-pull method or by mechanical feed at the time of recording signals, and tracking control is carried out by a phase difference tracking method at the time of reproduction. Thus, a phase change type optical disk which enables phase difference reproduction and is erasable may be realized. In a phase change type optical disk having a phase difference reproduction structure, servo mechanism at the time of reproducing signals may be stably controlled by causing the reflectance of a blank portion to be higher than the reflectance of a recording mark portion.

Abstract: The present invention relates to an optical information recording medium including a disk-shaped transparent substrate and a recording layer for recording, reproducing or erasing information by irradiation of laser light, the recording layer being formed over the substrate. The recording layer of the present invention includes information tracks including groove tracks and land tracks that are formed alternately in a radial direction of the disk. The information tracks comprise information recording regions and address regions interposed between the information recording regions, the information recording regions and the address regions being arranged along the tracking direction of the laser light.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing an information signal on/from both concave portions and convex portions of guide grooves formed on a recording medium is disclosed.

Abstract: An optical information recording medium of the present invention includes first to Nth recording layers (where N is an integer equal to or larger than 2) arranged sequentially from an opposite side of an incident side of a laser beam. The laser beam that has entered from one side is irradiated onto any one of the first to Nth recording layers, thereby recording and reproducing information. At least any one of the first to Nth recording layers includes a correction information recording portion. The correction information recording portion contains a correction information for correcting a laser beam intensity based on a change in a transmittance of the second to Nth recording layers between an unrecorded state and a recorded state.

Abstract: An apparatus for writing on and reading an overwritable optical disk comprises an identifier detector that identifies a recording condition in the sector to be overwritten, and a delay time controller circuit that sets a variation range of the start point for writing according to the recording condition. The record timing of the modulated data signal is changed at random within the set variation range when overwriting the sector of the optical disk.

Abstract: The present invention relates to a recording and reproducing method and apparatus for an optical disk of the phase transition type that can be overwritten. According to this invention, the capacity of repeated rewriting of the optical disk is expanded by recording either non-inverted write data or inverted write data at random. The deterioration due to the repeated rewriting at a start point and an end point of the recording is suppressed by recording a synchronizing signal before the write data and/or dummy data after the write data in the way such that thermal stress is less likely to occur. A record end position can be determined precisely by detecting a stop pulse to stop recording.

Abstract: An apparatus for writing on and reading an overwritable optical disk comprises an identifier detector that identifies a recording condition in the sector to be overwritten, and a delay time controller circuit that sets a variation range of the start point for writing according to the recording condition. The record timing of the modulated data signal is changed at random within the set variation range when overwriting the sector of the optical disk.

Abstract: The present invention relates to a recording and reproducing method and apparatus for an optical disk of the phase transition type that can be overwritten. According to this invention, the capacity of repeated rewriting of the optical disk is expanded by recording either non-inverted write data or inverted write data at random. The deterioration due to the repeated rewriting at a start point and an end point of the recording is suppressed by recording a synchronizing signal before the write data and/or dummy data after the write data in the way such that thermal stress is less likely to occur. A record end position can be determined precisely by detecting a stop pulse to stop recording.

Abstract: A substrate for an optical recording medium, has

Abstract: The present invention relates to a recording and reproducing method and apparatus for an optical disk of the phase transition type that can be overwritten. According to this invention, the capacity of repeated rewriting of the optical disk is expanded by recording either non-inverted write data or inverted write data at random. The deterioration due to the repeated rewriting at a start point and an end point of the recording is suppressed by recording a synchronizing signal before the write data and/or dummy data after the write data in the way such that thermal stress is less likely to occur. A record end position can be determined precisely by detecting a stop pulse to stop recording.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing an information signal on/from both concave portions and convex portions of guide grooves formed on a recording medium is disclosed.

Abstract: A substrate for an optical recording medium, includes recording tracks formed in guide grooves on a disc; and an address section having an address pit sequence formed between the recording tracks in the guide grooves along an information reading direction of the recording tracks. The recording tracks in the guide grooves are divided into a prescribed number of zones. In each of the zones, the center of the address section corresponding to a recording track in the radially outermost or radially innermost guide groove is disposed so as to shift in a radial direction of the disc in relative relationship to the center of the recording track in the guide groove.

Abstract: A light generating apparatus includes: a submount; a semiconductor laser chip mounted on the submount; a substrate which is mounted on the submount and includes an optical waveguide; and a substance having a predetermined thickness which is disposed between the semiconductor laser chip and the substrate. In an oscillation wavelength stabilizing apparatus for a light source, the light source is a semiconductor laser which includes: an active region for providing gain; and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength.

Abstract: In an optical information recording medium having at least two information layer, guide grooves for tracking or sample pits or information pits corresponding to information signals are formed on a surface of a first substrate. A first information layer formed by a thin film for reflecting a portion of a light beam made incident on the first substrate and permitting penetration of a portion of the light beam is formed on a surface of the first substrate. Guide grooves for tracking or information pits corresponding to information signals are formed on a surface of a second substrate. A second information layer having a reflectance higher than that of the first information layer is formed on a surface of the second substrate. Between the first information layer and the second information layer, there is formed a transparent separation layer for positioning the first information layer and the second information layer to be spaced a predetermined distance apart from each other.

Abstract: Tracking control is carried out by a push-pull method or by mechanical feed at the time of recording signals, and tracking control is carried out by a phase difference tracking method at the time of reproduction. Thus, a phase change type optical disk which enables phase difference reproduction and is erasable may be realized. In a phase change type optical disk having a phase difference reproduction structure, servo mechanism at the time of reproducing signals may be stably controlled by causing the reflectance of a blank portion to be higher than the reflectance of a recording mark portion.

Abstract: An optical recording device comprises: a basic pulse generator 60 including a starting-end pulse generation circuit 2, a burst gate generation circuit 4, and an end pulse generation circuit 6; a data-length detector 61 including a front mark detector 40, a front space detector 41, a recording mark detector 42, a back space detector 43 and a back mark detector 44; a timing controller 62 including a starting-end pulse selecting circuit 14, a starting-end starting position setting circuit 15, a starting-end pulse delaying circuit 19, an end pulse selecting circuit 21, an end starting position setting circuit 35 and an end pulse delaying circuit 25; a pulse synthesizer 63 including an AND gate 27 and an OR gate 36; and a laser driver 64 including an erasing current source 32, a recording current source 33, and a switch 34.

Abstract: An optical information recording medium according to the present invention includes a first information recording layer on which information is to be recorded by laser light; and a second information recording layer on which information is to be recorded by the laser light which has passed through the first information recording layer. The first information recording layer includes at least one of a reproduction-only area and a recording and reproduction area. The second information recording layer includes a test recording area. At least one of the reproduction-only area and the recording and reproduction area, and the test recording area is located such that one of the reproduction-only area and the recording and reproduction area includes an area of the first information recording layer through which the laser light for recording information in the test recording area passes.

Abstract: An optical information recording medium includes: a substantially disk-shaped substrate; and a recording layer formed on a surface of the substrate for recording, reproducing and erasing information by irradiation with a laser beam. A test recording region for test recording and an information recording region for recording the information at least are arranged on the surface of the substrate. In the test recording region and the information recording region arranged on the surface of the substrate, a test recording track and an information recording track respectively are formed in a spiral-shaped arrangement or in a concentric arrangement. A track pitch of the test recording track is wider than a track pitch of the information recording track.

Abstract: An optical information recording medium has a first information layer composed of at least three thin films, which is capable of reflecting a portion of incident light and permitting the passage of a portion of incident light. The optical recording medium also has a second information layer composed of at least four thin films. Information can be recorded on or reproduced from the second information layer with light that has passed through the first information layer. The first and second information layers are separated by a transparent separation layer. The first information layer may be composed of a first dielectric layer, a recording layer and a second dielectric layer, and the second information layer may be composed a third dielectric layer, a second recording layer, a fourth dielectric layer and a reflecting layer.

Abstract: An optical information recording medium having two or more information layers, wherein the irradiation of either the information layer with a laser beam converging thereon causes information signals to be recorded or reproduced; the nearer positioned information layer than the farthest information layer as viewed from the incidence side of the laser beam has a recording layer varying between two optically detectable states, and