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 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: A magnetic recording medium and a process for making the same provides a plurality of micro- or nano-machined recesses in a non-magnetic carrier layer. The recesses are machined by a fiber laser and when filled with a magnetic material, provide isolated single-domains on the magnetic recording media. The micro- or nano-machining of the recesses produces single domains of extremely small dimensions to increase the recording density on magnetic recording media.

Abstract: A disc recording medium that is capable of being rotated at a high speed to improve an information transfer rate. The recording medium has a residual stress acting as a tensile force. An annular reinforcing member having a temperature coefficient different from the disc and adapted to be bonded to the disc is used in the recording medium.

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: Optical disc, e.g., CD-R, DVD, DVD-R, comprising a polymer substrate and a radiation-cured coating provided by curing a radiation-curable coating composition having a pH greater than or equal to 3 and comprising at least one acrylate monomer, and advantageously diacrylate monomers and oligomers and monomers having acrylate functionalities of from 1 to at least 3, wherein the optical disc exhibits jitter of no greater than about 35 ns after being subjected to an environment having a temperature of at least 80° C. and a relative humidity of at least 85% for a period of at least 96 hours.

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.

Abstract: A recording medium which includes a first substance and a second substance, wherein an external energy is applied to at least one of the first and second substances to react them in order to change the optical characteristics of the substances for recording information, the recording medium including: a first layer composed of a first substance including at least one of S and Se, a second layer composed of a second substance including a metal, and a barrier layer being disposed between the first and second layers, which allows the reaction between the first and second layers when laser beam for recording is irradiated as an external energy, and suppresses the reaction between the first and second layers when laser beam for recording is not irradiated. Alternatively, the recording medium can be free from the barrier layer, and the second substance can be arranged to have two or more compositionally different portions or two or more phases with a different crystalline state.

Abstract: The invention relates to methods for making mold tools. More particularly, the mold tools are used for molding a resin substrate which has fine pits, i.e., concavities and protuberances. The invention also pertains to a method for manufacturing a resin substrate. Such resin substrates may be used as an optical disk, a magnetic disk, a hard disk, etc., for recording data. According to a preferred embodiment of the invention, a first metallic (Ni) mold tool (father) is made which is a duplicate of a master substrate, then a resin mold tool (mother) is made which is a duplicate of the first metallic mold tool and finally a second metallic (Ni) mold tool (son) is made which is a duplicate of the resin mold tool. Both the father and son may be referred to “as a stamper”.

Abstract: A rigid magnetic memory disc (28) is disclosed having a substantially flat, central hard core substrate (12) and an overlying smoothing layer (14) deposited thereon. The smoothing layer (14) is subsequently polished to a predetermined thickness. The smoothing layer (14) should be capable of having a surface finish better than approximately ten Angstroms Ra. After the smoothing layer (14) is polished, an appropriate magnetic medium (16) and alternately, a nonmagnetic finishing layer (16) are then applied to the rigid disc substrate (10) as necessary, ultimately rendering a finished magnetic disc.

Abstract: A method of manufacturing an optical disc master includes preparing the surface of a glass master plate (2) with an adhesion promoter 4. A photoresist layer (6) is coated on the adhesion promoter (4). This photoresist layer (6) is subjected to a first exposure of a modulated laser beam (8) to produce an exposed photoresist layer (10) corresponding to the modulation information of the laser beam (8). A transparent sheet (16) is placed on the photoresist layer (6). This sheet (16) contains a distinguishing mark to be located in the optical disc. White light (18) from a second light source is passed through the sheet (16) onto the photoresist layer (6) to expose the upper surface of this layer (6). The exposed part of this upper surface provides a pattern (22) corresponding to the mark on the sheet (16). The exposed master plate (2) is then developed to form the pits (12) and a reproduction (24) of the pattern (22).

Abstract: A magnetic data storage medium includes a dedicated transducing head contact zone for engaging an air bearing slider, primarily when the disk is stationary and also during disk accelerations and decelerations. The contact zone has a dual baseline texture, formed by first creating a recessed region within the transducing head contact zone, and then by forming multiple nodules or other texturing features within the recessed region. The texturing features project upwardly from a recessed surface of the recessed region, and also project above an upper surface of the disk by an amount less than the texturing feature height. Consequently, the texturing features are large enough to counteract stiction due to liquid lubricant meniscus formation, yet also have heights sufficiently low relative to the upper surface to allow reduced transducer flying heights.

Abstract: In a glass substrate for use in an information recording medium which is specified by Young's modulus E, the Young's modulus E is determined by the following equation (1) so that the Young's modulus exceeds 90, E=&Sgr;xi&rgr;i&Sgr;xisi  (1) where Si=2NA(Gi/M) (4&pgr;/3) (mRA3+nRO3), &rgr;i is the density of component i, NA is the Avogadro's number, Gi is dissociation energy of the component i, Mi is molecular weight of the component i, RA and RO is ionic radius of cation A and anion O of the component i defined by AmOn.

Abstract: A rewritable optical recording disk has a substrate with an increased thickness that is greater than or equal to approximately 1.5 mm and less than or equal to approximately 2.5 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: The present invention provides a protective film with high mechanical strength free from dust. A protective film 14 of an optical recording medium 2 is formed by applying and curing a composition for protective films obtained by dispersing in a curable binder material a first lubricant compatible with said binder material and a second lubricant incompatible with said binder material but compatible with said first lubricant. The incompatible second lubricant is stably and homogeneously dispersed to enhance lubricity and slidability while any excessive amount of the lubricant does not deposit on the surface of the protective film. The binder material is desirably photocurable.

Abstract: By keeping the imaginary number portion k of the complex index of refraction of the film of the light absorbing layer 3, the mean film thickness dav of the light absorbing layer 3, and the absorbency A related thereto within an appropriate range, the present invention provides an optical information recording medium with good recording sensitivity and playback properties, which makes possible high speed recording by increasing the sensitivity to the recording beam and stable recording with sufficient reflectivity, and which can reduce jitter. In the present invention, 0.13≦A≦0.21 where A (Abs) is the absorbency of the light absorbing layer at the wavelength of the recording beam; and 6.0≦k.dav≦12.0 where k is the imaginary number portion of the complex index of refraction of the film in the light absorbing layer and dav (nm) is the mean film thickness of the light absorbing layer, at the wavelength of the recording beam.