Abstract: When a light beam is applied to a surface of a back-coated magnetic recording medium such as a long magnetic tape, the light reflected by the recording medium surface is polarized. The angle of rotation of the plane of polarization of light reflected by the magnetic layer of the recording medium is different from the angle of rotation of the plane of polarization of light reflected by the back coating layer of the recording medium. The light reflected from the surface of the recording medium is applied to a polarizer which allows only linearly polarized light that vibrates in a predetermined direction to pass through itself. Then, the intensity level of the linearly polarized light is detected to determine whether the light was reflected from the magnetic layer or the back coating layer.

Abstract: A joint inspection apparatus comprises a light irradiating device for irradiating light to a tape joint at which two tape edge portions are joined together, and a light receiving device for receiving the light irradiated by the light irradiating device to the tape joint and passing through the tape joint or reflected by the tape joint. A judgment device is provided for judging the extent of a deviation of the two tape edge portions from each other in the tape width direction at the tape joint on the basis of information on the optical amount of the light received by the light receiving device on both sides of the tape joint.

Abstract: A magnetic tape cassette checking system is provided with a lock releasing mechanism (11), a cover opening mechanism (12) and a position detecting device (13), and checks whether a cassette cover can be correctly opened and closed. The lock releasing mechanism comprises a cylinder and a lock releasing pin which is moved back and forth by the cylinder and is adapted to push a lock member of the cassette to a releasing position. The cover opening mechanism comprises a cylinder, a cover opening plate which is moved up and down by the cylinder, a photoelectric switch disposed near the plate, and a damper spring connecting the plate with the cylinder, and is adapted to push the cover of the cassette to the opened position. The position detecting device comprises two pairs of photoelectric switches and detects whether the cover of the cassette is in the closed position.

Abstract: A method of detecting tape defects according to a light amount signal obtained from the surface of a tape by scanning the width of the tape surface with a light beam is disclosed. The light beam is caused to scan beyond the tape edges. The light amount signal is differentiated to obtain a light amount differential signal. A tape defect in the vicinity of the tape edge is detected if the light amount differential signal has a level different from a predetermined reference level or if the point in time when a change in the level of the light amount differential signal is different from a predetermined point in time.

Abstract: A tape winding device in which magnetic tape is wound onto a reel. One or more magnets exert a magnetic force on the wound tape in a direction along the thickness of the tape, that is, along a diameter of the reel, in order to neatly wind the tape. The magnets may be movable radially to maximize the magnetic force or be moved axially to control the axial position of the tape independently of the reel flanges.

Abstract: A videotape cassette is provided with a cassette cover which is mounted on a cassette casing to be movable between a closed position and an open position and is urged toward the closed position by a closing spring. Further, the cassette casing is provided with a lock mechanism which prevents the cover from being accidentally opened when the cassette is free. The lock mechanism comprises a lock member which is movable between a locking position in which it is engaged with the cassette cover in the closed position to lock the cassette cover to the closed position, and a lock releasing position in which it releases the cassette cover, and a locking spring which normally urges the lock member toward the locking position. In order to check whether the cover can be correctly opened and closed, the lock member is first urged toward the lock releasing position and then released. Then the cover is urged toward the open position and then released. Thereafter the position of the cover is detected.

Abstract: A joint inspection apparatus comprises a light irradiating device for irradiating light to a tape joint at which two tape edge portions are joined together, and a light receiving device for receiving the light irradiated by the light irradiating device to the tape joint and passing through the tape joint or reflected by the tape joint. A judgment device is provided for judging the presence or absence of an overlap of the two tape edge portions one upon the other at the tape joint on the basis of information on the optical amount of the light received by the light receiving device in the vicinity of the tape joint.

Abstract: A method for inspecting a tape splice for defects in which the splice region between two sheets is irradiated with a light beam, the tapes are longitudinally conveyed relative to the light beam, a one-dimensional light detector means receives the portion of the light beam transmitted or reflected by a linear region of the sheets inclined at a prescribed angle to the transverse direction of the sheets, and the presence/absence of a splice defect is discriminated from change or lack of change in the quantity of light received by the light detector means; and an apparatus for carrying out this method.

Abstract: A joint inspection apparatus comprises a light irradiating device for irradiating light to a tape joint at which two tape edge portions are joined together, and a light receiving device for receiving the light irradiated by the light irradiating device to the tape joint and passing through the tape joint or reflected by the tape joint. A judgment device is provided for judging the size of a gap between the two tape edge portions at the tape joint on the basis of information on the optical amount of the light received by the light receiving device in the vicinity of the tape joint.

Abstract: A tape winding method and apparatus in which a magnetic tape is wound on a reel having only one flange. During winding a magnetic field is applied across the width of the magnetic tape and a pressure disk biases the tape against the flange. Both mechanisms true the edge of the tape to the flange.

Abstract: A method and apparatus for loading a magnetic tape into a cassette in which the tape winding appearance is controlled and improved. Friction sheets are disposed around the hub onto which the tape is to be wound, preferably on both sides of the tape winding area. Compressed air is blown into the cassette to press the friction sheets against the edges of the tape as the tape is wound.

Abstract: A method and apparatus for winding a magnetic tape on a reel. A magnetic field is applied along the width of the wound tape to pull the magnetic tape against a flange. Air is jetted between the tape layers at the point where the tape is wound so that the layers can more freely move relative to each other. Air pressure is reduced at another point around the wound tape so as to deplete the air so entrained between the layers.

Abstract: A tape winding device for magnetically aligning the edge of a magnet tape. A permanent magnet is disposed on a side of a take-up reel opposite the side of a drive shaft rotating the take-up reel. The magnet extends over the diameter of the wound tape.

Abstract: In a decorative winding method for a magnetic tape or the like, a tape reel comprising a lower flange and a reel shaft one end of which is secured to the lower flange is supported with the other end of the reel shaft facing up. One end of a tape is clamped to the reel shaft, and the tape is wound up on the reel shaft while the tape is pushed onto the lower flange side by the weight of a cap placed on the upper side edge of the tape. An upper flange is then secured to the other end of the reel shaft, thereby obtaining the tape reel with the tape wound up in an aligned winding appearance.

Abstract: The asbestos-free calcium silicate heat-resistant material composition, comprises:(A) 100 parts by weight of a mixture of lime and siliceous material having a CaO/SiO.sub.2 mole ratio of 0.6-1.2;(B) 20-170 parts by weight of xonotlite obtained by hydrothermal synthesis;(C) 15-150 parts by weight of fibrous wollastonite; and(D) water in an amount of 2-8 times as much as that of the total solid contents and is produced by a method which comprises the steps of:(i) molding a slurry of a uniform mixture of that recited above in (A) to (D).(ii) steam curing said molded body in an atmosphere of steam under a pressure of not less than 6 kg/cm.sup.2 to react the siliceous material with the lime; and(iii) heat treating said steam cured product to remove water therefrom at a temperature of not lower then 100.degree. C. under atmospheric pressure.

Abstract: This invention relates to a method for making an asbestos-free calcium silicate board, which comprises preparing a slurry of a mixture of silicic acid material, lime material, fibrous wollastonite and pulp with a large amount of water, forming the slurry into a raw board by means of the sheet-forming technique, steaming the raw board and drying. This invention also relates to the board produced in accordance with the above method.

Abstract: An air-pervious sheet predominantly of polytetrafluoroethylene, the sheet being reinforced by being fused to a liquid-pervious reinforcing material layer which is capable of retaining its original form even when heated to a temperature of 270.degree. to 280.degree. C. The sheet preferably consists of a polytetrafluoroethylene fibrous powder having an average fiber length of 100 to 5,000 microns, an average shape factor of not less than 10, and an anisotropic expansion factor of 1.30 to 7.00 adhered by means of molten polytetrafluoroethylene having an average particle diameter of 0.05 to 0.5 microns to a liquid-pervious reinforcing material layer which is capable of retaining its original form even when heated to a temperature of 270.degree. C. to 380.degree. C.

Abstract: A suction port device comprising a shield member extending along at least one of the peripheral edges of an opening formed in a suction port body, so that the suction force of the vacuum cleaner can be made substantially uniform in intensity over the entire length of the suction port body.