Abstract: An optical disk allows recording of information at high density and accurate reproduction of such high-density recorded information. The optical disk according to the invention has a shutter layer, formed directly or through an intermediate layer on a substrate, for tightening a light beam to be irradiated to read or write information, the shutter layer containing semiconductor fine particles.

Abstract: A disk manufacturing apparatus produces a master disk of optical disks with a high recording density in a short time. According to one aspect, the apparatus comprises a housing forming a vacuum space; a holder holding a master disk having a recording surface subjected to an electron beam resist application process in the housing; a plurality of cold-cathode emitter elements, arranged two-dimensionally within a plane of beam irradiation to the master disk, irradiating an electron beam toward the master disk of optical disks when driven; and a driver selectively driving the a plurality of cold-cathode emitter elements. According to another aspect, the apparatus comprises at least one cold-cathode emitter element irradiating an electron beam toward the master disk when driven; a magnetic field lens, disposed between the cold-cathode emitter element and the master disk, focusing the electron beam emanated from the cold-cathode emitter elements.

Abstract: A method for writing data to and reading data from an optical disk that has address information written on its land between grooves or in its pregrooves. Because data is written to and read from the pregrooves or land where no address is written, continuous signals can be written to and read from the disk without format change. Further, the data area is widened by the amount of the nonexistent address area.

Abstract: An optical information record carrier (optical disk, conventionally) has multiple reflective surfaces, each carrying separate information and each readable by an optical beam directed from the same side of the record carrier. The top most reflective surface reflects light of a first waveband and passes light of a second waveband. The next top most reflective layer reflects light within at least part of the second waveband. The record carrier is formed by producing a first reflective layer having a first pit pattern in the surface of a transparent substrate, pressing said first substrate/layer combination to a transparent stamper having a second pit pattern, with a radiation hardening liquid resin therebetween, irradiating the resin by applying radiation to said resin through said stamper, peeling off said stamper, applying a second reflective layer to said hardened resin surface opposite the surface in contact with said first reflective layer, and applying a protective layer to said second reflective layer.

Abstract: An optical information record carrier (optical disk, conventionally) has multiple reflective surfaces, each carrying separate information and each readable by an optical beam directed from the same side of the record carrier. The top most reflective surface reflects light of a first waveband and passes light of a second waveband. The next top most reflective layer reflects light within at least part of the second waveband. The record carrier is formed by producing a first reflective layer having a first pit pattern in the surface of a transparent substrate, pressing said first subtrate/layer combination to a transparent stamper having a second pit pattern, with a radiation hardening liquid resin therebetween, irradiating the resin by applying radiation to said resin through said stamper, peeling off said stamper, applying a second reflective layer to said hardened resin surface opposite the surface in contact with said first reflective layer, and applying a protective layer to said second reflective layer.

Abstract: A method for recording and reproducing data on an optical disk of a phase-change type which is capable of being over-written, comprising steps of: writing the data by a writing light beam, erasing the written data by an erasing light beam, and reading the written data by a reading light beam, characterized by a step for initializing the optical disk so that a width of an initialized region is wider than the diameter of a spot written by the writing light beam on the optical disk.

Abstract: An acoustic diaphragm formed of beryllium or an alloy composed mainly of beryllium. Said diaphragm has a crystal structure having its plane (1120) preferentially orientated in parallel with the surface of the diaphragm.

Abstract: An acoustic vibrating element, such a domed speaker diaphragm A or a phonographic pickup cantilever B, is formed by vapor deposition on an easily separable mold member 5 of tantalum or tantalum alloy when a mixture of a hydrocarbon gas and an inert gas is passed through a furnace heated to a temperature of 1150.degree. C.-1250.degree. C. at a flow rate in excess of 200 cm/min. The c-axis crystalline orientation of the resulting graphite element is substantially perpendicular to its surface, which provides a Young's modulus above 16,000 Kg/cm.sup.2.

Abstract: Elements for a tone-arm system such as arm pipes, head shells, cartridge bodies, and arm bases are fabricated from a kneaded mixture comprising polypropylene and flaky graphite powder. The mixture may further include polymethyl methacrylate and/or rubber-like material. Graphite flakes are preferably oriented parallel to the surface of the element. The elements show improved temperature resistance.

Abstract: Vibratory elements for use in audio equipment are fabricated from a kneaded mixture comprising polypropylene and flaky graphite powder. The kneaded mixture is rolled into a sheet in which graphite flakes are oriented parallel to the surface, and the sheet is then formed into a desired shape, for example, a dome- or cone-shaped diaphragm and a cantilever, as by vacuum forming, air-pressure forming or press molding. The mixture may further include polymethyl methacrylate and/or rubber-like material. The elements are characterized by improved temperature resistance.

Abstract: A diaphragm for acoustic instruments such as speakers is produced by blending and kneading a thermoplastic resin such as polyvinyl chloride resin with graphite powder, rolling the blend into a sheet until graphite particles are oriented, and forming the sheet into a desired diaphragm shape. The diaphragm of the composite material containing graphite particles oriented shows an improved combination of density, elasticity and internal loss.

Abstract: Vibratory elements for use in audio equipment are fabricated from a kneaded mixture comprising post-chlorinated polyvinyl chloride and flaky graphite powder. The kneaded mixture is rolled into a sheet in which graphite flakes are oriented parallel to the surface and the sheet is then formed into a desird shape, for example, a dome- or cone-shaped diaphragm and a cantilever, as by vacuum forming, air-pressure forming or press molding. The mixture may further include polymethyl methacrylate and/or rubber-like material. The elements are characterized by improved temperature resistance.

Abstract: A molding composition comprising a thermoplastic resin in admixture with flaky graphite and carbon black is molded into an acoustic article which shows a high specific modulus of elasticity due to graphite and an increased internal loss due to carbon black. Preferred molding compositions contain 10-90 wt % of polyvinyl chloride or a vinyl chloride-vinyl acetate copolymer and 90-10 wt % of graphite flakes plus carbon black submicron particles. Carbon black is present in an amount of 0.1-2 parts per part of flaky graphite. Speaker diaphragms, arm pipes and head shells are fabricated from the molding composition. The composition is kneaded and rolled to orient the graphite flakes, and subsequently molded into an article, which is then optionally carbonized or graphitized.

Abstract: A head shell for a record player tonearm comprises a composite material essentially consisting of a thermoplastic resin and graphite powder. The composite material is prepared by kneading the components, rolled to impart a degree of orientation to the graphite powder particles, which are in the form of flaky graphite and then molded into a shell, along the surface of which the graphite particles are oriented. Head shells wherein the composite material is oxidized at the surface and head shells wherein the composite material is carbonized or graphitized are also included. A light weight, rigid head shell having a high specific modulus of elasticity is obtained through a simple procedure at low cost.

Abstract: An arm pipe for a record player tonearm comprises a composite material essentially consisting of a thermoplastic resin and graphite powder. The composite material is prepared by kneading the components, rolled to impart a degree of orientation to the graphite powder particles, which are in the form of flaky graphite and then molded into a pipe, along the surface of which the graphite particles are oriented. Arm pipes wherein the composite material is oxidized at the surface of the pipe and arm pipes wherein the composite material is carbonized or graphitized are also included. A light weight, rigid arm pipe having a high specific modulus of elasticity is obtained through a simple procedure at low cost.

Abstract: A method of producing a diaphragm of an acoustic instrument having the steps of blending powders of carbon such as graphite, carbon black or the like and a thermoplastic or a thermosetting resin, shaping the resultant blend into a desired form and then carbonizing the shaped blend. As a result, it has become possible to produce a diaphragm of an acoustic instrument, having a light weight, high rigidity and a large ratio of Young's modulus to density.