Abstract: A magnetic disc with good abrasion resistance and improved durability, which comprises a non-magnetic substrate, a magnetic layer comprising a metal magnetic powder formed on one side of the substrate and a coating comprising an inorganic powder having a Mohs hardness of not less than 4 formed on the other, back side of the substrate, which has good abrasion resistance and improved durability.

Abstract: A disk cartridge which comprises a cartridge case, a disk rotatably encased in the cartridge case, and a cleaning sheet supported on the inside surface of the cartridge case by welding, the cartridge case being composed of a thermoplastic synthetic resin, and the cleaning sheet being composed of non-woven fabric made mainly of acrylic fibers at least on the disk-facing side of the cleaning sheet and being fixed to the inside surfaces of the cartridge case by ultrasonic or heat welding has distinguished disk-handling characteristics and cartridge case-fixing characteristics.

Abstract: The invention relates to a device for preventing a turntable for a record player from slipping off a shaft rotatably extending through a boss made of a metal fixed to the turntable. The turntable has integrally formed therewith slot means for receiving two bent ends of leg portions of a generally U-shaped retainer spring and a plurality of support projections. With the slot means and the plurality of support projections, the retainer spring is mounted to the turntable such that the leg portions thereof extend substantially in parallel to each other and across a circular axial end of the boss. The shaft is formed with a radial groove to receive the leg portions of the retainer spring. The plurality of support projections will serve as a spacer to keep the leg portions apart to prevent interference contact bwtween the leg portions and a bottom wall of the radial groove which otherwise would hamper smooth rotation of a turntable.