Abstract: An optical disk 100 is provided with a hub 3 at the central portion of a substratel. A relationship Y/X?0.015, preferably Y/X?0.05 is satisfied where X is the projected area of the substrate 1 and Y is a contact area between the hub 3 and the substrate 1. As result, no slippage occurs between the hub 3 and the substrate 1 even when they are rotated at high speed than conventional. With this higher rotational speed, the data transfer rate is improved, and irregular rotation and the camming are suppressed, thereby reducing tracking errors and write/read errors.

Abstract: A cartridge includes upper and lower half segments butting against each other and containing a disk, a shutter provided on one side of the cartridge half segments for exposing or alternatively enclosing the disk, and a torsion spring attached to the shutter for biasing the shutter in a closing direction. An insertion opening is formed in a side portion of the cartridge for permitting insertion of the torsion spring therethrough from outside, and a protective wall is provided upright between the insertion opening and the disk to define a space by the wall and the upper half segment. The space is so sized as to permit the torsion spring to pass therethrough while leaving a small clearance, with legs thereof directed laterally.

Abstract: A board for an IC card includes a main body in the shape of a plate. A recess is formed in the main body for receiving and adhering a component therein. The recess includes a bottom wall integrated as one body with the main body, and an adhesion section for adhering the component. A wall of the adhesion section is an uneven surface. Ribs may be provided which extend from an inner side of the recess to contact the component.

Abstract: A plate for an IC card having recesses for mounting components is formed by injection molding of plastics. First, a mold for forming recesses for mounting components is formed to have a slide core. After molten resin is filled in a cavity, the slide core is forced to penetrate into the cavity. Thus, the molten resin is removed by the slide core so as to form the recesses and walls. Because the resin has been filled beforehand, even if the wall is thin, the filling process is carried out normally, and the walls can be formed without increasing an injection pressure.

Abstract: A powder for sintering is prepared by the wet mixing of a finely and uniformly divided alumina powder of high purity having a primary particle diameter not exceeding 0.15 micron and an average particle diameter not exceeding 0.3 micron, and a partially stabilized zirconia powder of high purity having an average particle diameter not exceeding 0.3 micron. After granulation and molding, the mixed powder is sintered at a temperature of 1300.degree. C. to 1500.degree. C. to make a sintered body having an average grain size not exceeding 0.7 micron.

Abstract: A light transmitting sintered body of cordierite has a composition equal or close to the stoichiometric composition of cordierite which is represented as 2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2, consists mainly of a phase of cordierite crystals, and has a total transmittance of at least 20%. A method of preparing it is also disclosed.

Abstract: An oxide sintered product represented by the formula(TiO.sub.2).sub.1-x (SbO.sub.5/2)x(0.1.gtoreq.x.gtoreq.0.005)and having a bulk density of not less than 4.1 g/cm.sup.3.

Abstract: There is provided a tape cartridge comprising a tape receiving member formed near a tape running path in the tape cartridge for receiving a tape, and a tape pushing member arranged to face the tape receiving member through the tape, the tape pushing member being arranged to move between a tape pinching position in which the tape is pinched between the tape receiving member and the tape pushing member, and a cancellation position in which the tape pushing member moves away from the tape. Accordingly, when the tape pushing member is positioned at the tape pinching position, the tape cartridge can prevent the tape from protruding from the front surface of the tape cartridge.

Abstract: In a recording tape cartridge having a movable front lid and a movable dust cover for protecting a recording tape, there is provided a locking member for locking the dust cover in a closed position.

Abstract: A recording tape cartridge comprising a case body, tape reels for winding a recording tape and a braking mechanism for preventing rotation of the tape reels when the recording tape cartridge is not used, the braking mechanism comprising a pair of guide wall projections formed on a bottom section of the case body, a stopper member having braking members for engagement with teeth formed on flanges of the respective tape reels and being guided by the guide walls so as to move between a first position where the braking members can engage at least one of the engaging teeth of the tape reels for preventing rotation of the tape reels and a second position where the braking members are disengaged from the teeth to allow rotation of the tape reels, a spring member for resiliently biasing the stopper member toward the first position and engaging member formed by a hook like member or plate on the top portion of the guide walls so as to prevent disengagement of the stopper member from the guide walls in an upward direct

Abstract: The present invention is directed to a magnetic recording tape cartridge capable of preventing the loosening of a magnetic recording tape comprising a tape adjusting member made of a resilient plate for stretching an intermediate portion of the magnetic recording tape; a pair of wall members formed in the cartridge with a gap defined therebetween to removing or detachably receive the tape adjusting member; and a raised member projected from a main plate portion of the tape adjusting member which is adapted to be engaged with a part of one of the wall members, thereby preventing undesired displacement of the tape adjusting member.

Abstract: A magnetic recording tape cartridge comprising a pair of tape reels each having a bottom flange with a plurality of engaging teeth on the peripheral edge of the bottom flange and a tape reel stopping means for engagement of one of the engaging teeth of the tape reel, the tape reel stopping means being biassed by a resilient plate spring to prevent undesired rotation of the tape reel.

Abstract: A powder composition for producing cordierite is obtained by mixing a water-soluble magnesium salt; a water-soluble aluminum salt; a silicon source selected from the group consisting of organic silicon compounds, silica, silica sol and, silica gel; and an organic solvent, adding to the resultant mixture an ammonia-alkaline solution of ammonium carbonate thereby producing a precipitate, separating the precipitate, and drying the separated precipitate.

Abstract: A magnesia ceramic for high-frequency electric insulation is produced by using, as the principal component, magnesia and adding thereto a calcium-magnesium-phosphate and at least one member selected from the group consisting of the oxides of aluminum, silicon, beryllium and tungsten.