Abstract: A disc cartridge which includes a mistaken recording inhibiting member, the mistaken recording inhibiting member having a mistaken recording inhibiting portion for closing a mistaken recording detection hole formed in the cartridge main body, an actuating portion for movement between a first position of closing the mistaken recording detection hole and a second position of opening the mistaken recording detection hole, and an indicating portion positioned facing an indicating hole formed in the cartridge main body for visually indicating, by means of a mark or color, through the indicating hole the sort of the disc housed within the cartridge main body when the mistaken recording inhibiting member is at a predetermined one of the first position or the second position.

Abstract: A method for mounting a magnetic plate on a disc substrate. The method includes the steps of placing the magnetic plate within a housing recess formed in the disc substrate, abutting a horn of an ultrasonic wave generating unit generating torsional vibrations on a rim of the housing recess of the disc substrate under application of a predetermined pressure, and ultrasonically forming a protrusion directed towards an inner space of said housing recess for mounting the magnetic plate on the disc substrate by protrusion.

Abstract: A manufacturing method of a shutter for a cartridge which is accommodating therein a recording medium includes the steps of punching out a plate-shaped metal material so as to provide a shutter of a developed shape having a pair of plate-shaped portions and a coupling portion for coupling the pair of plate-shaped portions, shaping the punched-out member in such a fashion that the pair of plate-shaped portions are opposed to each other across the coupling portion and that a spacing between free end sides of the pair of plate-shaped portions become narrower than a spacing of the pair of plate-shaped portions at its portion coupled by the coupling portion, and shaping the shaped member such that a spacing between free ends of the pair of plate-shaped portions of the member shaped by the second process become substantially equal to a spacing of the pair of plate-shaped portions at its portion coupled by the coupling member.

Abstract: A double-side optical disc formed by a pair of optical disc halves bonded together, and a process for producing the double-side optical disc. An adhesive is applied to the disc halves, which are then bonded together at an angle relative to each other in which the direction of the adhesive flow on one disc half will intersect the direction of the adhesive flow on the other disc half. In this manner, satisfactory flatness of the optical disc may be achieved without being affected by surface irregularities of the adhesive layer.

Abstract: A disc for recording information signals includes a disc substrate of a synthetic resin having a center hole and an information signal recording layer formed on one major surface and a magnetic plate arranged on the major surface for closing the center hole. A recess for accommodating the magnetic plate is formed on the major surface of the disc substrate for surrounding the center hole. At least a part of the rim of the recess is thermally deformed for forming one or more lugs for holding the magnetic plate disposed in the recess with respect to the disc substrate by the lug(s).

Abstract: A double-side optical disc formed by a pair of optical disc halves bonded together, and a process for producing the double-side optical disc. An adhesive is applied to the disc halves, which are then bonded together at an angle relative to each other in which the direction of the adhesive flow on one disc half will intersect the direction of the adhesive flow on the other disc half. In this manner, satisfactory flatness of the optical disc may be achieved without being affected by surface irregularities of the adhesive layer.