Abstract: A method of manufacturing a glass substrate for a storage medium by pressing a glass material between an upper and a lower dies. The method includes a heating step of heating the glass material arranged between the upper and lower dies, a pressing step of pressing the heated glass material via the upper and lower dies, and a cooling step of having, after the pressing step, a cooling member contact the upper and lower dies to cool them together with the molded glass material arranged between the upper and lower dies. During the heating step and the pressing step, a vacuum atmosphere is maintained in a space containing the dies and the glass material. When the pressing step has completed, an inert gas is filled in the space to set a pressure in the space equal to an ambient pressure.

Abstract: A glass material (4) is placed in a forming die including a pair of upper and lower dies (1, 2) and a control member (3) for controlling the space between the upper and the lower die, and then heated, softened, and molded by pressure into a glass substrate in the shape of a parallel plate. The amount of thermal contraction of the control member is smaller than that of the glass material. Therefore, the glass substrate is released from the die when cooled after molding. The present invention can provide a glass substrate that is excellent in smoothness and form accuracy of the surface, and that is suitable for recording media such as magnetic disks that are inexpensive and suitable for mass production.

Abstract: An optical waveguide includes a first cladding, a second cladding, and a core. The core is embedded in the first cladding so as to be exposed on one principal surface of the first cladding that is opposed to the second cladding. The first cladding and the second cladding are arranged so as to sandwich the core. The core is a product formed by a reaction in which a polymeric material that includes branched polysilane and polysiloxane is subjected to at least one process selected from heating and ultraviolet irradiation. The refractive index of the core is higher than the refractive indices of the first cladding and the second cladding.

Abstract: A glass material (4) is placed in a forming die including a pair of upper and lower dies (1, 2) and a control member (3) for controlling the space between the upper and the lower die, and then heated, softened, and molded by pressure into a glass substrate in the shape of a parallel plate. The amount of thermal contraction of the control member is smaller than that of the glass material. Therefore, the glass substrate is released from the die when cooled after molding. The present invention can provide a glass substrate that is excellent in smoothness and form accuracy of the surface, and that is suitable for recording media such as magnetic disks that are inexpensive and suitable for mass production.

Abstract: A glass material (4) is placed in a forming die including a pair of upper and lower dies (1, 2) and a control member (3) for controlling the space between the upper and the lower die, and then heated, softened, and molded by pressure into a glass substrate in the shape of a parallel plate. The amount of thermal contraction of the control member is smaller than that of the glass material. Therefore, the glass substrate is released from the die when cooled after molding. The present invention can provide a glass substrate that is excellent in smoothness and form accuracy of the surface, and that is suitable for recording media such as magnetic disks that are inexpensive and suitable for mass production.

Abstract: A press die and a molding process can form a disk member having a shaft shaped portion at a center with satisfactory circularity and flatness in a disk portion, dimensional precision in the shaft shaped portion, and concentricity between the disk portion and the shaft shaped portion at the center. The press die is designed for press molding of a glass substrate of a disk member with a shaft shaped portion at a center thereof. The press die includes an upper die forming an upper surface of the disk member, an intermediate die having a shaft forming hole portion for forming a shaft shaped portion projecting from a disk portion of the disk member, a lower die for forming a lower surface of the shaft shaped portion and a guide member for guiding the upper die, the intermediate die and the lower die.

Abstract: The present invention provides a production method of a glass substrate for magnetic recording medium having an inner diameter and an outer diameter comprising an edge polishing step of a glass substrate. In one embodiment of the production method, it has the edge polishing step in which the inner or outer diameter of the glass substrate is chucked, in a single disk process, and the edge surface of the outer or inner diametral side of the glass substrate is polished using a polishing tape or a grindstone. Further, the present invention relates to a magnetic recording medium using the glass substrate. The production method of a glass substrate of the present invention can perform a polishing of edge surface in a high-quality without generating a defect on the surface of the glass substrate. The present invention can provide a superior magnetic recording medium by using the glass substrate.

Abstract: A press-molding die can manufacture magnetic disks suitable for the zone-texture technique in large quantities and at a low price by forming smooth surface areas and rough surface areas on the surface of the press-molding die. A manufacturing method for this press-molding die is provided. A magnetic-disk glass substrate that has improved CSS properties and allows a lower flying height is formed using this press-molding die. An intermediate layer is formed by sputtering on a die base material. A mask having an aperture is formed on the intermediate layer. The surface of the intermediate layer is roughened by etching in the aperture. A first protective layer is formed by sputtering in the etched portion. After the mask has been removed, a second protective layer is formed on the intermediate layer by sputtering. The surface roughness of the rough surface portion is reflected by the surface roughness of the first protective layer.

Abstract: A press-molding die comprises a base material, an intermediate layer formed on a surface of the base material and a protective layer formed on the intermediate layer. The base material comprises an inorganic oxide. The intermediate layer comprises a material that adheres to both the base material and the protective layer and is heat resistant at high temperatures wherein the die is used. The protective layer comprises at least one metal film selected from the group consisting of tungsten (W), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), osmium (Os), rhenium (Re), tantalum (Ta) and alloys thereof.

Abstract: A mobile radio communication apparatus containing: a transmission stopping unit for stopping the operation of transmitting a radio frequency signal when receiving a stop control signal; a first comparator for receiving a strength indicating signal, and comparing the amplitude of the strength indicating signal with a reference voltage to detect a first condition in which the amplitude of the strength indicating signal is below the reference voltage, to output a state indicating signal indicating whether or not the first condition is currently detected; a unit for obtaining and outputting a first duration in which the first condition continues; a unit for detecting a second condition in which the amplitude of the strength indicating signal decreases at a rate exceeding a predetermined decreasing rate; a unit for determining a second duration in which the operation of transmitting the second radio frequency signal is to be stopped, based on a plurality of values of the first duration, where the plurality of valu

Abstract: A tape cassette has a magnetic tape wound and housed in a casing, the magnetic tape having a magnetic recording layer in the form of a ferromagnetic thin metal film. The tape cassette has a trap layer disposed near a portion of the magnetic tape. The trap layer is made of a resin having at least an amino group or an amide group. Even when the tape cassette is used in harsh environments in the presence of corrosive gases, the trap layer adsorps corrosive gases which have entered the tape cassette, thereby protecting the magnetic tape against deterioration.

Abstract: A magnetic recording medium comprises steep mountain-shaped protrusions having heights ranging 50-600 .ANG. and distributed at a rate of 1.times.50.sup.5 -1.times.10.sup.8 protrusions/mm.sup.2 on a surface of ferromagnetic metal layer and further thereon a lubricant layer; the magnetic recording medium is suitable for VTR tape which has a satisfactory durability for repeated use and eliminates head clogging and squealing.

Abstract: A magnetic recording media, e.g. VTR tape is improved by providing an undercoating layer on a polyester film substrate, the undercoating layer being formed under a ferromagnetic thin film and being an even-scattering of a large number of inorganic or organic granules distributed at a rate of 1000/mm.sup.2 or more.

Abstract: In a magnetic recording medium having an oxygen-containing thin ferromagnetic metal layer formed on a nonmagnetic substrate, at least one compound capable of suppressing the hydration of the ferromagnetic metal ions by acting thereon is located on or in the vicinity of the surface of the thin ferromagnetic metal layer. A lubricant may further be applied on the thin ferromagnetic metal layer.

Abstract: 1. A resist for use in forming a positive pattern with a radiation comprising a copolymer composed of methyl methacrylate and methacrylic acid and a cross-linking agent having the following general formula: ##STR1## wherein R is H or CH.sub.3, x is an integer of 1 to 9, and y and z are zero, or an integer of 1 to 3.2. A process for forming a positive pattern on a substrate with a radiation.