Abstract: A recording and reproducing apparatus for an optical disk of the transitional type that can be overwritten, having an optical information recording medium. The medium has a guide groove and a sector ID area. Information is recorded by irradiation with a light beam to change a state of a photo-sensitive record layer, and the recording may be stopped by the generation of a stop pulse. The stop pulse may be generated by an altered width of the guide groove before the sector ID area, or by one or more larger prepits before the sector ID area.

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: A track on the disk is divided into plural concentric zones on the radial position thereof. During recording, the angular velocity varies according to the zones accessed for recording, and the disk is driven at a rotational velocity whereby the angular velocity is constant within any single zone but decreases as the radial position of the zone of the accessed track approaches the outside circumference of the disk. During reproducing, the disk is driven at a rotational velocity whereby the angular velocity is constant in all zones. The range of change in the relative linear velocity of the head to the track is thus smaller and the change in the recording conditions is less during recording. During reproducing, there is no delay time required for rotational control of the disk, and the desired track can be more quickly accessed.

Abstract: A code conversion method and apparatus is provided for scrambling and modulating data. The method and apparatus includes scrambling an input main data unit based on any of plural types of pseudo-random number sequences, and modulating the scrambled main data unit based on any of plural types of modulation data. An output main data unit is produced from the modulated main data unit, and a calculated value representing a difference between a number of 0 bits and a number of 1 bits included in the output main data unit is obtained. Any of the modulation data is then selected dependent upon the calculated value.

Abstract: A method of manufacturing an optical information recording medium comprising the steps of: forming a plurality of component thin films on a substrate or on a sample at a predetermined film-forming speed and within a predetermined film-forming time in sequence; measuring spectral reflectance of the multilayer thin film formed on the substrate or on the sample; comparing the measured value of the spectral reflectance and the standard value of the spectral reflectance to detect the difference between them; compensating at least one of the film-forming speed and the film-forming time based on the detected difference; and forming a plurality of thin films based on the compensated film-forming speed and with the compensated film-forming time. Consequently, a thickness of each component thin film of the optical information recording medium can be measured easily and production loss in measuring a film-forming speed can be decreased.

Abstract: An optical information recording medium, which includes a substrate, and a recording thin film layer provided on the base material and adapted to form variation in an amount optically detectable by absorbing at least laser light so as to record information by partially varying the recording thin film layer and to reproduce the information by optically detecting the variation amount. The optical information recording medium further includes transparent layers each provided in contact with the recording thin film layer, and each of the transparent layers has optical thickness in which, in at least two different wavelengths .lambda., integral multiple of .lambda./2 is added to the thickness giving the large laser light absorption and large optical variation amount, respectively.More specifically, the optically detectable amount is of a reflectance factor variation, and in the different wavelengths .lambda.1 and .lambda.

Abstract: A track on the disk is divided into plural concentric zones on the radial position thereof. During recording, the angular velocity varies according to the zones accessed for recording, and the disk is driven at a rotational velocity whereby the angular velocity is constant within any single zone but decreases as the radial position of the zone of the accessed track approaches the outside circumference of the disk. During reproducing, the disk is driven at a rotational velocity whereby the angular velocity is constant in all zones. The range of change in the relative linear velocity of the head to the track is thus smaller and the change in the recording conditions is less during recording. During reproducing, there is no delay time required for rotational control of the disk, and the desired track can be more quickly accessed.

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: An optical information recording medium includes: a substrate including a groove having a concave shape and a land having a convex shape adjacent to the groove; and a recording layer on the substrate, wherein the recording layer consists of a material which changes between a first state and a second state whose optical property is different from that of the first state, a first portion of the optical information recording medium including a portion in the first state of the recording layer having a first reflectance, and a second portion of the optical information recording medium including a region in the second state of the recording layer having a second reflectance which is different from the first reflectance, whereby information is recorded onto the groove and the land, and wherein a ratio of the first reflectance to the second reflectance, a phase of reflected light from the first portion and a phase of reflected light from the second portion are set such that at least one of an amplitude and a carrier

Abstract: A track on the disk is divided into plural concentric zones on the radial position thereof. During recording, the angular velocity varies according to the zones accessed for recording, and the disk is driven at a rotational velocity whereby the angular velocity is constant within any single zone but decreases as the radial position of the zone of the accessed track approaches the outside circumference of the disk. During reproducing, the disk is driven at a rotational velocity whereby the angular velocity is constant in all zones. The range of change in the relative linear velocity of the head to the track is thus smaller and the change in the recording conditions is less during recording. During reproducing, there is no delay time required for rotational control of the disk, and the desired track can be more quickly accessed.

Abstract: In an optical information recording medium such that a recording layer undergoing an optically detectable phase change by absorbing a laser beam is formed on a transparent substrate having geometrically concavo-convex groove tracks concentrically or spirally formed on its surface, the shapes of the groove tracks are variably determined continuously or stepwise depending on the material of the substrate, the structure of the recording layer, and the radial locations of the tracks so that the thermal diffusivity of heat generated in the recording layer becomes larger in an inner part than in an outer part whereby the differences of recording characteristics between in an inner part and in an outer part are suppressed, and the effective recording area is enlarged.

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: Phase-change-type optical recording medium comprises a first dielectric layer, a recording layer made of a phase change material, a second dielectric layer and a reflecting layer wherein the thicknesses of the first and second dielectric layers are determined for a given thickness of the recording layer so that the following conditions are satisfied;.DELTA.A+.DELTA.R.gtoreq.20% and .DELTA.A.gtoreq.5%wherein.DELTA.A=A(cry)-A(amo),A(cry), A(amo): light absorption rates of the recording layer in the crystal state and amorphous state, respectively,.DELTA.R=R(cry)-R(amo),R(cry) and R(amo): light reflection rates of the recording lates in the crystal state and amorphous state, respectively.

Abstract: An optical recording medium according to the present invention includes a substrate, and a recording film formed on the substrate, when receiving a laser beam for recording, the recording film taking either a first structural state or a second structural state according to the intensity of the laser beam; when receiving a laser beam for reproducing, the recording film partially changing the optical phase of the laser beam for reproducing according to the structural state, thereby changing the intensity of the laser beam for reproducing, wherein the optical absorbance of the recording film in the first structural state is substantially equal to that of the recording film in the second structural state, and the refractive index of the recording film in the first structural state is substantially different from that of the recording film in the second structural state.

Abstract: An optical information recording medium includes: a substrate including first tracks having a first face and second tracks having a second face, the first face and the second face being optically at different positions in a direction of an incident light beam; and a recording layer provided on the substrate on which an optically detectable change is caused by irradiating the light beam; wherein the first and second tracks have an information recording area and an address area having a control information for the information recording area in a direction of the tracks, the address area has address pits in a part of the first tracks, the address pits being formed in a pattern according to specified code signals, and the information recording area has an portion on which information is recorded, the portion including at least the second tracks.

Abstract: An optical information recording medium, wherein concave and convex shaped guide grooves narrower in width W than the spot diameter of the laser beam is formed in the face of the recording film layer of a substrate, and the recording film layer undergoes optically detectable changes caused by the application of a laser beam thereto, the detectable changes being due to the changes in the optical phase of the reflected light or the transmitted light, and the changes in the optical phase being caused in the direction of reducing the optical phase difference between concave and convex portions of guide grooves disposed in the substrate.

Abstract: An optical recording medium having a recording film composed of a mixture of a metal and an oxide or alternating layers of a metal and an oxide is formed by vacuum evaporation or sputtering from separate metal and oxide sources without inducing an oxidation-reduction reaction between the metal and oxide. The oxide has a standard enthalpy of formation which is higher than that of an oxide obtained by oxidizing the metal. Information is recorded by irradiating portions of the film with a laser beam so as to cause an exothermic oxidation-reduction reaction between the metal and oxide, thereby causing an optically detectible change in the optical constant of the film at the portions irradiated.

Abstract: Described is an optical recording medium having a mixture or integrated layers of a metal and an oxide which react with each other under an exothermic reaction at a high temperature upon receiving an irradiation of a laser. The metal and the oxide are in a relation that the oxide has a standard enthalpy of formation higher than that of the oxide obtained by oxidizing the metal. An area irradiated with a laser spot is heated to a high temperature and the oxide at the area is reduced by the metal into a metal which changes in the optical constant and can be detected optically. The reduction reaction in an exothermic reaction generates a thermal energy in addition to the thermal energy of the irradiated laser. The optical recording medium of this structure can make the recording work more efficient. A manufacturing method of the optical recording medium and a recording method using the same are also disclosed.

Abstract: Phase-change-type optical recording medium comprises a first dielectric layer, a recording layer made of a phase change material, a second dielectric layer and a reflecting layer wherein the thicknesses of the first and second dielectric layers are determined for a given thickness of the recording layer so that the following conditions are satisfied;.DELTA.A+.DELTA.R.gtoreq.20% and .DELTA.A.gtoreq.5%wherein.DELTA.A=A(cry)-A(amo),A(cry), A(amo): light absorption rates of the recording layer in the crystal state and amorphous state, respectively,.DELTA.R=R(cry)-R(amo),R(cry) and R(amo): light reflection rates of the recording lates in the crystal state and amorphous state, respectively.

Abstract: In a method of recording optical information, one of correcting ways for correcting the pulse waveform of the input signal to be recorded is selected depending on change in relative velocity between the optical information recording medium and the laser beam spot; and thereafter the laser beam output power is modulated in a range between an erasing level and a recording level in accordance with the corrected pulse waveform of the modulated input signal. Then a digital input signal corrected by modulation in pulse width is overwritten onto an optical information recording medium with a single laser beam spot by forming recording marks corresponding to the input pulse signal.