Abstract: This invention relates to an optical disc recording apparatus, an optical disc recording method, and an optical disc, and the present invention is applied to, for example, apparatus for recording on a compact disc, compact discs, and compact disc players, and sub-data strings are recorded so that the main data strings is reproducible by an optical pickup for reproducing the main data string and the main data strings are protected from being copied illegally without any adverse effect on reproduction of the pit-and-land main data strings. The sub-data string ED is recorded by locally changing the reflectance of the reflection film in the form of irregularity such as pit or mark at the timing which does not affect the position information of the edge.

Abstract: A product for recording information by use of laser light includes a recording layer being able to change between an amorphous state and a crystalline state so as to record information, the recording layer having a thickness falling within a first range defined relative to a wavelength of the laser light, a protection layer having a thickness falling within a second range defined relative to the wavelength of the laser light, a heat releasing layer having a thickness falling within a third range defined relative to the wavelength of the laser light, and a transparent substrate supporting the layers. The first, second, and third ranges are selected such that a phase of the laser light reflected by the amorphous state and a phase of the laser light reflected by the crystalline state have a phase difference larger than a predetermined phase amount.

Abstract: An optical information recording medium includes a recording layer that changes reversibly between a crystalline state and an amorphous state. The irradiation of the recording layer with laser beams at a predetermined wavelength changes the recording layer from one selected from the group consisting of the crystalline state and the amorphous state to the other state. The absorptance Ac of the laser beams in the recording layer when the recording layer is in the crystalline state is larger than the absorptance Aa of the laser beams in the recording layer when the recording layer is in the amorphous state. Crystallization accelerating layers for accelerating the change of the recording layer from the amorphous state to the crystalline state are formed in contact with both surfaces of the recording layer.

Abstract: An information recording medium according to an embodiment of this invention has a plurality of disk-like information recording layers, which are adhered to each other within an allowable decentering error range, and a data area assured on each information recording layer, and has guard tracks within the range of a predetermined radial distance from the radial position of the innermost periphery of the data area toward the outer periphery.

Abstract: An optical recording medium having a recording layer which comprises an Sb—Te alloy containing excess amount of Sb over the vicinity of Sb70Te30 eutectic composition and shows reversible phase changes on light beam irradiation between a crystalline state and an amorphous state differing from each other in optical properties, a method of writing and erasing information using the same, and a process of producing the same are described.

Abstract: An optical disk and a method of fabricating the optical disk capable of improving the signal quality and the productivity are disclosed. The optical disk includes a plurality of reflective layers stacked on a substrate, amorphous layers formed among the reflective layers which include a small amount of oxide therein, a recording layer, formed on the reflective layer, for recording information, and a cover layer formed on the recording layer.

Abstract: A phase-change recording medium with Sb3Te compounds which are formed by initialization-less process steps is provided through the formation of recording media having layered structure including suitably selected materials together with methods for fabricating such recording media, thereby leading to DVD-ROM compatible recording media capable of achieving recording density of 2.6 GB or more on a disc of 120 mm in diameter. The recording medium includes an Sb3Te recording layer and a crystallization accelerating layer formed contiguously with the recording layer. The crystallization accelerating layer is formed to suitably include impurities as record stabilization agents. At least one additional impurity layer may be formed contiguous to said recording and/or crystallization accelerating layer.

Abstract: An information storage device includes a cathodoconductive medium and pairs of electrodes in contact with the medium. Data storage areas are located within regions between the electrode pairs. A read operation on data storage areas between a pair of electrodes may be performed by creating an electric field between the electrodes, scanning an electron beam across the storage areas, and monitoring a cathodocurrent created by the carriers. Changes in magnitude of the cathodocurrent indicates the states of the storage areas. The energy beam may be supplied by an electron emitter or a near-field optical source.

Abstract: Cholesteric liquid crystal compositions and a recording medium which includes cholesteric liquid crystal composition are disclosed. The cholesteric liquid crystal composition has a characteristic, in a cholesteric phase, of reflecting visible light in accordance with temperature. By rapidly cooling the display from a cholesteric phase, the material can be solidified in a reflection state. The cholesteric material also has the characteristic during a transition from a solid phase to a cholesteric phase of having of an enthalpy &Dgr;Hch at a substantially constant value during a time when a temperature thereof increases during one of differential thermal analysis and differential scanning calorimetry.

Abstract: The optical recording medium of the present invention has a phase change recording layer. This recording layer contains at least two elements selected from Sb, Te, Ge, and In as main elements, and at least one element selected from rare earth elements (Y, Sc, and lanthanoid), Zr, Hf, Ti and Sn as an auxiliary element, and also, a eutectic mixture can exist in the recording layer. The optical recording medium of the present invention can be operated at a high transfer rate, and has a high storage reliability.

Abstract: An optical disk has a multi-layer tuned optical coating overlying both small bumps to store pre-recorded information and lands onto which information is written to and read. The optical coating includes a phase-change metal/alloy layer formed over the disk substrate and a dielectric layer formed over the phase-change layer. An optical disk according to the invention has specific topological features and sizes.

Abstract: A magnetic recording medium comprises, on a substrate, a recording auxiliary layer, a recording holding layer, recording control layer, and a recording layer. The recording layer is constructed by using a ferri-magnetic material having perpendicular magnetization. The data can be recorded at a super high density by using the recording and reproducing head of the present invention, because the recording layer has the perpendicular magnetization. The disappearance of data, which would be otherwise caused by the thermomagnetic relaxation phenomenon, is suppressed after recording the data, because the recording layer has large coercive force at the room temperature. The data, which is recorded at the super high density on the magnetic recording medium, can be reproduced by using a magnetic resistance element carried on the recording and reproducing head.

Abstract: A multi-layer optical information recording medium has a first information layer located at the incident side for a laser beam and another information layer at the back thereof. Thus, it has a large capacity. A relationship that R1a<R1c and R2a<R2c holds for the reflectances R1a and R1c of the information layer in the in a recorded portion and in a non-recorded portion, and the reflectances R2a and R2c of the information layer in a recorded portion and in a non-recorded portion. A relationship that A1a<A1c holds between the absorptances A1c and A1a of the first information layer in the crystalline state and in the amorphous state, similarly, a relationship A2a<A2c holds between absorptances A2c and A2a of the second information layer in the crystalline state and in the amorphous state. Thus, signals can be written to the recording medium at a fast speed and at high sensitivity.

Abstract: A recording medium is disclosed which is removably loaded in an information providing apparatus and in which content information is recorded by the information providing apparatus. The recording medium includes a recording medium main body and a content identification section including content identification information detectable by the information providing apparatus, which indicates a kind of content information downloaded by the information providing apparatus.

Abstract: A method to store first information in a rotatable data storage medium and to dispose second information on a rotatable data storage medium. An apparatus comprising a constant linear velocity drive servo, a laser device, and a computer useable medium having computer readable program code disposed therein for sequencing laser irradiations to encode first information in a rotatable data storage medium and to dispose second information on a rotatable data storage medium. A rotatable disk storage medium having first information encoded in the information area and at least one human-readable pattern disposed on the clamp area and/or the information area.

Abstract: In a phase change optical recording medium in which writing, reading and/or erasing of information is conducted by utilizing change of phase of a recording layer by irradiation with light, the recording layer is made of a material containing oxygen in an amount of 1 to 30 atomic %; or the recording medium comprises an additional transparent dielectric layer 1 to 10 nm thick between the recording layer and the underlying transparent dielectric layer and the inserted transparent dielectric layer in contact with the recording layer comprising oxygen in a molar ratio greater than a molar ratio of oxygen in the underlying transparent dielectric layer; or the transparent dielectric layer underlying and in contact with the recording layer comprises oxygen in a molar ratio greater than a molar ratio of oxygen in the other transparent dielectric layer.

Abstract: When recording using magnetic field modulation recording, the magneto-optical recording medium which is disclosed is capable of satisfactory recording with a low magnetic field. This recording medium is a layered superposition of a recording layer 13 and an auxiliary recording layer 14 having a film thickness of less than or equal to 100 angstroms. The recording layer 13 is a film having an easy perpendicular axis of magnetization whose value of magnetization at room temperature is at least 150 emu/cc, and for example a heavy rare earth—transition metal alloy, a magnetic multilayer film which employs a precious metal, an oxide like a garnet or Spinel ferrite, or some other magnetic alloy may be used. The auxiliary recording layer 14 is typically a heavy rare earth—transition metal alloy, and has a Curie temperature higher (desirably at least 30K higher) than that of the recording layer 13.

Abstract: An optical information medium (20) for erasable recording by means of a laser-light beam (10) is provided. A substrate (1) holds a stack (2) of layers with a phase-change recording layer (5) between a first dielectric layer (4) and a second dielectric layer (6). A light-absorptive layer (7) is present proximate the recording layer (5) and is made of a compound of the formula QRx, in which Q is the element Si, Ge, Ti, Zr, Hf, Nb or Ta, R is the element O or N, and 0<x≦2.5, in order to achieve that 0.8<Ac/Aa<1.50, in which Ac and Aa are the respective quantities of laser-light absorbed in the recording layer (5) in the crystalline state and the amorphous state at a laser-light wavelength selected from a range of 350-450 nm. Thus high data rates and low data jitters are achieved at this short wavelength range by tuning x to an optimal value during manufacture of the optical information medium.

Abstract: An optical recording medium for at least one of recording and reproduction of information by focusing of light from an optical system on a recording layer, comprising a substrate, a recording layer formed on the substrate, a first protective layer formed on the recording layer, and an antireflection multilayer film, designed to be positioned at a near field distance from the optical system, formed on the first protective layer for preventing reflection of the light at the surface of the first protective layer and having predetermined optical characteristics for moderating a change of a reproduced signal intensity along with fluctuation of a distance between the antireflection multilayer film and the optical system, a method of producing the medium, and an optical recording and reproduction device including the medium.

Abstract: A reproducing layer having perpendicular magnetization in a single layer, an in-plane magnetic layer, and a recording layer having perpendicular magnetization are formed in this order. When the reproducing layer, the in-plane magnetic layer, and the recording layer have the Curie temperatures of Tc1, Tc2, and Tc3, these values satisfy conditions of Tc2<Tc1 and Tc2<Tc3. The reproducing layer has in-plane magnetization due to an exchange coupling with the in-plane magnetic layer at lower than Tc2. At Tc2 or higher, magnetization information is expanded and transferred from the recording layer to the reproducing layer, so that the reproducing layer has single-domain perpendicular magnetization.

Abstract: A product for recording information by use of laser light includes a recording layer being able to change between an amorphous state and a crystalline state so as to record information, the recording layer having a thickness falling within a first range defined relative to a wavelength of the laser light, a protection layer having a thickness falling within a second range defined relative to the wavelength of the laser light, a heat releasing layer having a thickness falling within a third range defined relative to the wavelength of the laser light, and a transparent substrate supporting the layers. The first, second, and third ranges are selected such that a phase of the laser light reflected by the amorphous state and a phase of the laser light reflected by the crystalline state have a phase difference larger than a predetermined phase amount.

Abstract: A phase-change optical information recording medium capable of recording information therein, reproducing recorded information therefrom, rewriting recorded information, and erasing recorded information therefrom, which phase-change optical information recording medium is provided with a recording layer containing therein a phase-change recording material including Ge, Ga, Sb, Te, and one element selected from the group consisting of Mg and Ca, which recording material is capable of performing a reversible phase transition from a noncrystalline phase to a crystalline phase and vice verse with the application of an electromagnetic wave thereto.

Abstract: The optical recording medium has sandwiched between protective layers a mask layer whose refractive index is changed in one part within a light spot when irradiated with a laser beam of 2 to 4 mW. In a region where the refractive index is changed or in other remaining regions, the difference in the amount of reflected light between the crystalline state and the amorphous state is so small that a reproduced signal is difficult to identify. By reducing the size of a portion where the reproduced signal can be seen, it is possible to read high-density recorded information.

Abstract: There are provided an optical recording medium and a method of manufacturing the optical recording medium. The optical recording medium has a pattern of microscopic depressions and projections molded thereon with a high fidelity of replication. The method of manufacturing the optical recording medium comprises the steps of forming a photoresist layer on a substrate; exposing a predetermined area of the photoresist layer formed on the substrate to form a plurality of trains of depressions in the photoresist layer; removing the photoresist layer between the adjoining depression trains to form a master; plating the master with a metal; separating the metal coating to form a master stamper; replicating the master stamper repeatedly an odd number of times to form a mother stamper; replicating the mother stamper to form a resin substrate; and forming at least a light-transparent layer on a surface of the resin substrate on which the mother stamper is replicated.

Abstract: An optical information medium (20) for high speed erasable recording by means of a laser-light beam (10) is provided. A substrate (1) has a stack (2) of layers with a first dielectric layer (5) and a second dielectric layer (7), a phase-change recording layer (6) between the first dielectric layer (5) and the second dielectric layer (7), and a reflective layer (3). The recording layer (6) has a compound of Ge and Te, and at least the first dielectric layer (5) consists of oxides of Ta and Si, nitrides of Si and Al, or carbides of Si, and is in contact with the recording layer (6). The recording layer (6) additionally may contain O or N in an amount up to 5 at. %. A broad usable composition range for low CET values is obtained. Thus high data rates are achieved.

Abstract: In a method of manufacturing a dielectric layer of ZnS—SiO2 for use in a phase change type optical disk, a target, which is sintered with mixture of ZnS and SiO2, is prepared. The dielectric layer is deposited by the use of a sputtering method in mixed atmosphere of argon gas, oxygen gas, and hydrogen gas. The deposition is carried out such that formation of dangling bonds is suppressed.

Abstract: An optical recording medium in accordance with the present invention is provided with a substrate, a mask layer, provided on the substrate, whose index of refraction changes due to light or heat of the substrate, and a recording layer that is provided away from the mask layer by a distance that is not more than a distance which allows the near-field light to reach. The mask layer generates a minute opaque region in a light spot and the recording layer is a magneto-optical layer. An optical recording and reproduction apparatus in accordance with the present invention uses the optical recording medium. This allows to provide an optical recording medium and an optical recording and reproduction apparatus that can suppress the erasure of recorded marks and carry out the reproduction again and again.

Abstract: An optical disk of the present invention includes a substrate and a recording layer disposed above the substrate, and reproduces an information signal by a DWDD system, using light incident from the substrate side. The optical disk further includes a first dielectric layer disposed between the substrate and the recording layer and a second dielectric layer disposed on the recording layer opposite to the substrate, wherein the recording layer is initialized with light having a wavelength &lgr; incident from the second dielectric layer side, and the thickness of the second dielectric layer is in a range of &lgr;/(12×n) to &lgr;/(2×n) (where n is a refractive index of the second dielectric layer).

Abstract: An optical disk including concentric or spiral grooves, a first series of pits formed in the interrupted portions, and a second series of pits formed in portions of lands. Both of the first and second series of pits represent address information. The portions of the lands and the interrupted portions of the grooves are located in different radial directions. With this arrangement, even when the optical disk has a reduced track pitch, accurate address information is obtained, achieving a high-density recording optical disk.

Abstract: A method of initializing a phase-change optical disk which is capable of preventing enlargement of an amount of jitter which takes place when the number of overwriting operations does not exceed several times. The surface of the phase-change optical disk, on which information signals will be recorded, is crystallized. Then, signals are recorded with marks and spaces in grooves along tracks of the phase-change optical disk so that initialization is performed. The initialization is performed in such a manner that the length of each of spaces is shorter than a shortest length of spaces of information signals.

Abstract: A near-field optical recording medium comprises a recording layer capable of writing, reading and erasing information using an evanescent light, the evanescent light having a beam spot size smaller than the wavelength of a source light, wherein the recording layer is a stable amorphous layer mainly comprising a photochromic compound having a glass transition point of 55° C. or higher and a molecular weight of 3000 or less.

Abstract: An optical recording medium and a method for fabricating the same. A read only data region, a writable/readable data region and a content recording region are formed on a transparent substrate. The read only data region is used to store prerecording data which can only be read but is unable to be rewritten. The writable/readable data region is used to read and write data, while the content recording region is used to record initial address information of the recorded data in the read only data region, the writable/readable data region and the content recording region. A recording layer in the writable/readable data region is formed with the derivative of cyanine dye, phthalocyanine dye or azo dye. Or alternatively, the recording layer is made of an alloy containing tellurium, germanium, or antimony, or an alloy containing indium, silver, antimony or tellurium.

Abstract: A recording medium having sufficient characteristics, such as signal characteristics at an elevated density or recording durability, and a method for producing the recording medium. Specifically, there is provided an optical recording medium having a recording layer formed of a phase-change material capable of producing reversible phase changes between the crystal state and the amorphous state, in which the phase changes are induced in the recording layer on illuminating light rays on the recording layer to record and/or erase information signals. The recording layer contains Ag&agr;In&bgr;Sb&ggr;Te&dgr; as the phase-change material, in which the proportions of components &agr;, &bgr;, &ggr; and &dgr; in at% meet the relation of 6≦&agr;≦16, 1.1≦&dgr;/&bgr;≦2.2 and 2≦&ggr;/&dgr;≦3.

Abstract: An information recording medium which includes at least a recording layer, and first and second metallic layers disposed on an opposite side of an energy beam incident side of the recording layer and having different compositions, and in which the first one of the first and second metallic layers located closer to the recording layer contains Al, Ag, Au, Pt and Pd as its main components and a sum of contents of these atoms is 60% or more. Thereby recording and reproducing of information can be realized with a high reliability.

Abstract: An information recording medium which includes at least a recording layer, and first and second metallic layers disposed on an opposite side of an energy beam incident side of the recording layer and having different compositions, and in which the first one of the first and second metallic layers located closer to the recording layer contains Al, Ag, Au, Pt and Pd as its main components and a sum of contents of these atoms is 60% or more. Thereby recording and reproducing of information can be realized with a high reliability.

Abstract: A multilevel phase change optical recording medium comprises first to N-th (N≧2) phase change optical recording layers, wherein an i-th recording layer and a j-th recording layer, which are two recording layers arbitrarily selected from the first to N-th recording layers, meet the conditions of Ti>Tmi and &tgr;wi<&tgr;xi, and Tj<Tmj or &tgr;wj>&tgr;xj, with respect to a particular recording laser beam selected from recording laser beams having different power levels, where T is the maximum temperature of the recording layer in a recording operation, Tm is the melting point of the recording layer, Tx is the crystallizing temperature of the recording layer, &tgr;w is a time required for the recording layer to be cooled down from Tm to Tx after the laser beam irradiation, and &tgr;x is the crystallizing time of the recording layer.

Abstract: An optical disk having a recording layer onto which light is irradiated to perform recording/reproducing of information, comprising a super-resolution film for recording and a reflective film which are formed in the side opposite to the light entering side with respect to the recording layer, and a super-resolution film for reproduction formed in the light entering side with respect to the recording layer.

Abstract: A phase change optical disk has a multilayered structure obtained by sequentially forming at least a lower dielectric layer, recording layer, upper dielectric layer, and reflective layer on a substrate. The reflectance Rc of the disk with respect to light with a wavelength of 380 nm to 320 nm, when the recording layer is in a crystalline state, is lower than the reflectance Ra of the disk when the recording layer is in an amorphous state.

Abstract: In the multi-layer information medium having a plurality of information-storing layers according to the present invention, all of the information-storing layers exhibits excellent reading properties. The multi-layer information medium also exhibits good mechanical precision. The optical information medium has at least two annular information storing layers each storing recorded information and/or servo information on a disk-shaped substrate formed with a center hole or between a pair of disk-shaped substrates each formed with a center hole, and at least one of the information-storing layers is recorded or read by the recording beam or the reading beam which has passed through other information-storing layer(s).

Abstract: An optical information recording medium having a multilayer structure comprising at least a lower protective layer, a phase-change type optical recording layer, an upper protective layer and a reflective layer, on a substrate, wherein the phase-change type optical recording layer has a composition of Zn&ggr;1In&dgr;1Sb&zgr;1Te&ohgr;1, where 0.01≦&ggr;1≦0.1, 0.03≦&dgr;1≦0.08, 0.5≦&zgr;1≦0.7, 0.25≦&ohgr;1≦0.4, and &ggr;1+&dgr;1+&zgr;1+&ohgr;1=1, whereby overwrite recording is carried out by modulation of light intensity of at least strong and weak two levels, so that a crystalline state is an unrecorded state, and an amorphous state is a recorded state.

Abstract: A multilayer resonance device of the invention includes regularly stacked layers each formed by alternately stacking a magnetic substance and a dielectric substance with thickness regularity, and an irregular layer including a magnetic substance, having a thickness disaccording with the thickness regularity and disposed between the regularly stacked layers. Thus, the multilayer resonance device can attain a large Faraday rotation angle, a large magneto-optical effect, and a practical total layer thickness.

Abstract: An information recording medium wherein an optically detectable information recording medium is comprised of at least a substrate, a recording layer, and a resin layer. The information recording medium has surface roughness R&sgr; on the surface of the recording layer, which is in contact with the resin layer, under 5 nm. The information recording medium controls the reproduction signal noise, enables highly densified recording.

Abstract: The present invention provides an optical information medium having excellent weather resistance and repeating characteristics. The optical information medium has a barrier layer between a protective layer and a recording layer. The barrier layer includes GeN or GeON, and at least one element selected from the group consisting of Al, B, Ba, Bi, C, Ca, Ce, Cr, Dy, Eu, Ga, H, In, K, La, Mn, N, Nb, Ni, Pb, Pd, S, Si, Sb, Sn, Ta, Te, Ti, V, W, Yb, Zn and Zr.

Abstract: To provide a rewritable compact disk having a rewritable area interchangeable with a CD-RW, that is, a RAM area (105), and an area available only for retrieving, that is, a ROM area (104), on the same disk surface, a phase-change recording layer is formed in each of the RAM area and the ROM area, with a wobble groove being made in the RAM area, irradiation is carried out with recording light so that an amorphous mark is formed to record information and information is recorded in the form of a pre-pit string (60) in the ROM area, and further when measured using a wavelength of 770 to 790 nm and an optical pickup whose objective lens numerical aperture is 0.49 to 0.51, a ratio |I131 I2|/|I1−I2|a of values of push pull signals before and after recording in the RAM area is set to be in a range from 1.05 to 2.

Abstract: Noise of the read-out signal is reduced in an optical information medium comprising a supporting substrate and a reflective layer disposed on the supporting substrate wherein the reading beam irradiates the medium from the side where the reflective layer is formed. In addition, noise of the read-out signal is reduced without adversely affecting the recording properties in an optical information medium comprising a supporting substrate, and a reflective layer and a recording layer disposed on the supporting substrate in this order wherein the recording beam irradiates the medium from the side where the reflective layer is formed. In the medium, the reflective layer has a crystallite size of up to 30 nm.

Abstract: An audio recording apparatus provides a method of managing the video and audio navigation data for a rewritable recording medium, such as DVDs. The recording medium contains video and audio files in either originally recorded or user defined sequence. During recording, the apparatus prepares and updates start addresses for each navigation table containing such data as video and audio files. When reproducing information from the recording medium, the information tables which contain management data required for reproduction of the requested data are located directly by the start addresses. The data are read from the rewritable recording medium and reproduced in reference to the management data.

Abstract: An optical disk includes a standard area of a standard recording density provided on an inner peripheral side and a high density area of a higher recording density provided on an outer peripheral side. In each of the standard area and the high density area, a program area is provided so that an independent program can be recorded in each program area. In, one aspect of the invention, an optical disk includes, from the inner periphery to the outer periphery of the disk, a ROM area for read-only purpsoe, a RAM area in which information can be rewritten and a WO area in which information can be written only once.

Abstract: The optical recording medium (20) has a substrate (1) and a stack (2) of layers provided thereon. A phase change recording layer (5), having a melting point Tmp is sandwiched between a first (3) and a second (7) dielectric layer. A crystallization-accelerating layer (4, 6) is being interposed in contact with the recording layer (5). Further a reflective layer (8) is present and an optional cover layer (9).

Abstract: The rewritable data storage medium (1) has a rewritable recording layer (9) provided with a tracking structure (8). Said layer (9) has a data recording area (5). An erasable identification mark is present in an identification mark area (4, 4′) other than the data recording area (5). The data recording area (5) has a first tracking structure (8′), whereas the identification mark area (4, 4′) is substantially free from a tracking structure or has a second tracking structure (8″) substantially different from the first tracking structure (8′).

Abstract: Storage density in an optical data storage media and system is increased many times the resolution limit by fully utilizing the much smaller detection limit by differentiating and isolating the active data sites in the media optically. The tracks are preordained and predisposed to a specific optical property and value that is different from that of its “n” nearest neighbors but is identical to its nth neighbor and to the optical properties of the reading and writing optical system.