Abstract: The present invention provides an optical disc capable of effectively reducing a reproduction signal jitter value and obtaining a wider record power margin assuring a reproduction limit jitter value to obtain a preferable recording/reproduction characteristic even after a number of times of recording repeated. The optical disc includes the following films successively formed on a substrate 2: a first dielectric film 3; a phase change recording film 4 whose phase is changed between a crystalline state and an amorphous state thereby to record an information signal; a second dielectric film 5; and a light reflection film formed on the phase change recording film 4 and constituted by an Al alloy containing Cu in a range from 0.1 to 1.0 atomic %.

Abstract: The invention relates to an optical storage medium comprising a substrate and a storage layer, wherein the storage layer comprises a compound of the formula (I) or (II) in which A and A′, independently of one another, are unsubstituted or mono- or di-halo-, -hydroxy-, —C1-C6alkyl-, —C1-C6alkoxy-, -cyano- or -nitro-substituted phenyl, pyridyl, pyrrolyl, imidazolyl, furyl or thienyl, which can, if desired, be fused to a benzene ring, are halide, tetrafluoroborate or unsubstituted or with one or more halogen substituted C1-C6alkane-sulfonate, benzenesulfonate, C1-C6alkylbenzenesulfonate, C1-C6alkylsulfate or di-C1-C6alkyl-phosphonate of N—C1-C6alkyl-pyridiniumyl, or are unsubstituted or mono- or di-hydroxy-substituted C2-C6alkyl or C2-C6alkenyl, whose chain may be uninterrupted or interrupted by one or two oxygen atoms, B and B′, independently of one another, are 2 H, S, S2 or SO2, and n and n′, independently of one another, are each a number from 1 to 4.

Abstract: A recordable optical medium includes a transparent substrate, a dye recording layer on the transparent substrate, a reflective layer provided on the dye layer wherein the reflective layer comprises a mixture of silver and palladium in such proportions that the palladium comprises between 0.25 and 2.5 atomic percent of the mixture, and a protective layer formed over the reflective layer.

Abstract: Such an optical recording medium is disclosed that includes at least one layer of an information layer (11) for which at least any of an optical recording or reproducing is performed with an optical parameter of N.A. (numerical aperture)/&lgr;(wavelength)≧1.2[&mgr;m−1], and in at least its information signal area, its focus error amount is equal to or less than ±&lgr;/(N.A.)2/8 in a band equal to or more than a focus servo cut-off frequency of an optical recording and reproducing apparatus which performs at least any of the optical recording or reproducing while within ±&lgr;/(N.A.)2/4 when only the reproduction is performed.

Abstract: In an optical recording medium using writing and reading light having a wavelength of up to 690 nm and having a recording layer and preferably a reflective layer, the recording layer contains a chelate compound having an azo compound of specific structure as a ligand (i.e., azo metal complex dye). This results in an optical recording medium of the heat mode having advantages including the dye's sufficient solubility in a coating solvent which does not attack polycarbonate substrates and improved write/read characteristics with light having a wavelength of up to 690 nm.

Abstract: A rewritable optical recording disk has an increased thickness that is greater than or equal to approximately 1.5 mm. In particular, the disk may have a substrate with a thickness that is greater than or equal to approximately 2.3 mm and less than or equal to approximately 2.6 mm. The increased thickness of the substrate enhances the flatness of the recording disk relative to a recording plane. In particular, the increased thickness reduces process-induced surface variations such as warpage and tilt, and provides the disk with increased stiffness to resist deflection during use. The enhanced flatness enables data to be recorded on the disk in a consistent manner with greater spatial densities using techniques such as near-field, air-incident recording. The resulting disk thereby yields greater spatial density and data storage capacity.

Abstract: An optical information recording disc of DVD (Digital Video Disc) type having an information recordable layer(s) between a pair of substrates (i.e., sandwich structure) shows an improved mechanical strength and an improved storage stability when the substrate has an exposed area on its outer peripheral edge and the exposed area is placed in contact with a resin layer, or the substrate has an enlarged surface area (preferably it is exposed) on its outer peripheral edge and the enlarged surface area is placed in contact with a resin layer. An apparatus for preparing an optical information recording disc of DVD type having an improved mechanical strength and an improved storage stability is further disclosed.

Abstract: A process for manufacturing a metallized substrate using the island coating method, includes depositing a coating layer containing a radiation curable non-volatile film former. The coated part is then vacuum metallized to form the metal islands of the present invention. A layer of clear resinous protective dielectric topcoat containing a radiation curable non-volatile film former is then deposited to completely cover the layer of metal islands while maintaining the aesthetic properties of the metallizing island coating system at a reduced cost and with minimal variability among parts.

Abstract: The object is to hold the recording, reproduction and rewrite characteristics better than in the prior art. An information recording medium comprises an information recording thin film as a recording layer formed on a substrate for recording and/or reproducing information by the change in the atomic arrangement caused by the radiation of light. The medium further comprises at least one protective layer. The protective layer and the recording layer are formed in that order from the light incidence side, followed by forming at least one absorption control layer, thereby exhibiting a superior rewrite characteristic.

Abstract: A structure of an optical recording medium that mainly includes a first dielectric layer, a dye layer, a second dielectric layer, and a reflective layer formed on a substrate in sequence, and a method for fabricating an optical recording medium of the foregoing structure. The additional dielectric layers of the optical recording medium, instead of a quencher used in a conventional optical recording medium, increase the lifetime of a dye layer and reduce the fabrication cost. Furthermore, the additional dielectric layers are capable of isolating the dye layer from oxygen and moisture to enhance the lightfastness of the dye layer.

Abstract: Hotmelt adhesives with a melt viscosity of >100,000 mPas at 160° C. are suitable for bonding substrate halves in the production of digital versatile discs (DVDs) and afford major process-related advantages over known UV-curing adhesives. In their pigmented embodiment, they are able to combine the three functions of adhesive bonding, protecting the metallic reflection layer against corrosion and forming a covering background for a text/graphics layer.

Abstract: There is disclosed an optical data storage medium in which the weather resistance of the semitransparent reflective film is improved and the adhesive property between the semitransparent reflective film and a substrate is enhanced, and which has a higher reliability. In an optical data storage medium (6), on the side on which a reproduction light (8) is incident, a first information layer (9) is located while on the side opposite to the side on which the reproduction light (8) is incident, a second information layer (10) is located. A semitransparent reflective film (3) of first information layer (9) is AgPdCu alloy thin films containing 0.5 to 3.0 weight % Pd and 0.1 to 3.0 weight % Cu or AgPdTi alloy thin films containing 0.5 to 3.0 weight % Pd and 0.1 to 3.0 weight % Ti. At the wavelength 650 nm, the optimum film thickness of AgPdCu alloy thin film is 5 to 18 nm and the optimum film thickness of AgPdTi alloy thin film is 10 to 25 nm.

Abstract: A recording medium includes a transparent substrate; a crystalline phase-change layer provided over the transparent substrate; a dielectric layer provided over the phase-change layer; a metallic reflector layer provided over the dielectric layer; and the crystalline phase-change layer having a thickness and phase-change material selected so that data can be recorded in it on a first write, but on second or subsequent writes the written data results in at least a 50% increase in data jitter.

Abstract: Prepits in a sector header area are arranged on center lines of groove tracks or land tracks, and header signals are played back in a drive by using sum signals of split sensors, thereby providing resistance to disc tilt or track offset and improving margins.

Abstract: A bonded optical disk comprising first and second transparent substrates bonded with a light-permeable, pressure sensitive adhesive layer and at least one information recording layer wherein the pressure sensitive adhesive layer has been formed from a pressure sensitive adhesive precursor, having a viscosity of 10 to 5000 cps and being applied onto at least one of the first substrate and the second substrate by radiation curing and has a gel fraction of not less than 50% and a storage modulus of 1.0×104 to 1.0×107 dyn/cm2 at 25° C., or in place of the pressure sensitive adhesive layer, an adhesive layer derived from a radiation curable adhesive precursor having a viscosity of 500 to 10000 cps, and the adhesive precursor is subjected to a higher pressure than an atmospheric pressure, prior to being irradiated, as well as a method and an apparatus for producing a bonded optical disk.

Abstract: A multi-layered optical disc having superior recording/reproducing characteristics, in which the recording density in three-dimensional direction can be increased to increase the recording capacity, and its manufacturing method. A multi-layered optical disc 1 has a light reflecting layer 3, a second information recording layer 4, a transparent layer 5, a first information recording layer 6 and a light-transmitting layer 7 sequentially formed on a major surface 2a of its substrate 2. The laser light is illuminated from the light-transmitting layer 7 of the multi-layered optical disc 1 to record and/or reproduce information signals.

Abstract: A magneto-optical recording medium comprises, on a substrate, a reflective layer, a first dielectric layer, a recording layer, and a second dielectric layer successively in this order, for being irradiated with a recording or reproducing light beam coming from a side of the second dielectric layer. A diamond-like carbon layer as a self-lubricating layer is formed on the second dielectric layer. An optical head comprises a floating type slider installed with a solid immersion lens. A protective film having a self-lubricating property may be also formed on a bottom surface of the slider opposing to the optical recording medium. Even when the floating position of the optical head is varied, and the optical head contacts with the surface of the optical recording medium, then the sliding scratch scarcely occurs, because the optical head smoothly glides on the recording medium surface. A lubricating layer may be further formed on the self-lubricating layer.

Abstract: Disclosed is disc substrate consisting of SiO2—Al2O3—RO (RO=divalent metal) glasses having high specific elastic modulus of 36×106 Nm/kg or more or high Young's modulus of 110 GPa or more, high transition temperature of 700° C. or higher (high heat resistance), excellent surface smoothness (surface roughness Ra<5 Å) and high strength. The substrates exhibiting high specific elastic modulus or high Young's modulus and high strength enables to realize thinner magnetic discs and prevent breakdown of magnetic discs. Since glass substrates being composed of the glass have excellent heat resistance and flatness, the substrates can be subjected to heat treatment for improvement of magnetic layer characteristics and realize smaller flying height of magnetic head, i.e., higher recording density.

Abstract: A method for controlling the bonding layer thickness between facing surfaces of two optical discs having information areas during manufacture of an optical storage apparatus wherein a plurality of microspheres of a predetermined uniform diameter are selectively placed on a facing surface of one of the optical discs. A bonding material is placed on the facing surface of the other of the optical discs. Pressure is thereafter applied to the two optical discs to form a substantially uniform bonding layer thickness between the two optical discs upon curing of the bonding material.

Abstract: The present invention provides a new category of information storage material, nonstoichiometric metal-organic complex Ag1−&bgr;(TCNQ), which is particularly suitable for digital video disc (DVD-R) operated by blue laser (wavelength 450 nm) or red laser (wavelength 650 nm), wherein, Ag is silver, TCNQ is tetracyano-p-quinodimethane C12H4N4, &bgr; is a parameter chosen by its performance and &bgr;≦0.4. The material can produce apparent absorption change under the incidence of the above-mentioned two different lasers. When used as optical recording medium, it has the advantages of high signal-to-noise ratio, fast response and low cost. The actual number of write-erase cycles can be larger than 20. Therefore, its performance is better than a conventional DVD-R.