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.