Abstract: A write-protect shutter in a magnetic disk cartridge in which the two case walls are joined by a boss around which legs of the shutter slide. The fusing joining the boss to the case wall may cause a protrusion at the joint. The legs are formed with indentations to avoid the protrusion.

Abstract: Disclosed is a magnetic recording disk cartridge comprising a slide indicator movable step by step along one side wall of the casing to indicate the number of pictures already recorded in an associated magnetic recording medium, a ratchet member for preventing the slide indicator from moving backward, and a reset member for releasing the slide indicator from the ratchet member and permitting the return of the slide indicator to the start position. The combined action of these elements permits: first, the indication of the exact number of pictures recorded in the magnetic recording medium when the cartridge is removed from the camera body, with no danger of an erroneous indication of a lesser number than the number of the recorded pictures; and second, the return of the slide indicator to the start position if it is desired that the magnetic recording medium be erased and reused from the beginning.

Abstract: A magnetic recording disk cartridge comprises a flexible recording disk having a cylindrical hub secured to the central portion thereof, and a casing in which the recording disk is accommodated. The cartridge is provided with a locking member comprising a pair of resilient arms which are fixed to the casing and are urged toward each other to grip therebetween the hub to fix the recording disk with respect to the casing so that the surfaces of the recording disk are not brought into contact with the inner surface of the casing, and a releasing member movable between an inoperative position in which it is operatively removed from the resilient arms and an operative position in which it urges the resilient arms away from the hub to release the recording disk from the locking member. The releasing member is arranged to be automatically moved to the operative position when the cartridge is loaded in a system using it, e.g., an electronic camera.

Abstract: A magnetic disk cartridge has a case, a magnetic disk rotatably housed in the case, a cleaning liner positioned between the magnetic disk and an inner wall surface of the case facing the magnetic disk and extending at least from an inner edge portion to an outer edge portion of the recording area of the magnetic disk, and a lifter positioned between the inner wall surface of the case and the liner. One end portion of the lifter is secured to the inner wall surface of the case, and the other end portion of the lifter is raised obliquely from the inner wall surface of the case to form a rising portion which pushes up the liner and makes the liner uniformly contact the magnetic disk over the area from the inner edge portion to the outer edge portion of the magnetic disk. The lifter is subjected to heat setting when the rising portion is formed.

Abstract: A magnetic disk cartridge comprising a magnetic disk for conducting image recording and reproducing through high-speed rotation and a case having a magnetic head receiving hole near a diagonal line of the case is provided with a shutter member having a rotation center at the corner of the case nearest to the magnetic head receiving hole. The shutter member is rotated fanwise to open and close the magnetic head receiving hole. The magnetic head receiving hole is opened when a portion of the shutter member engages an exterior shutter opening contact member of a recording device upon insertion of the magnetic disk cartridge. The magnetic head receiving hole is closed upon removal of the disk cartridge from the recording device.

Abstract: A magnetic recording disk cartridge comprises a flat casing and a magnetic recording disk accommodated in the casing. The recording disk is rotated at a high speed when recording and reproducing video signals. An annular unwoven fabric is attached to each of the opposed major inner surfaces of the casing to be opposed to the outer margin of the recording disk.

Abstract: A magnetic recording disk cartridge comprises a recording disk having a circular recording medium and a hub secured thereto, and a casing for accommodating the recording disk. The cartridge is provided with a hub lock for preventing rotation of the recording disk and closing a magnetic head receiving opening in the casing when the cartridge is not in use. The hub is provided with a plurality of axially extending engaging grooves on the peripheral surface thereof, and the base wall of the casing is provided with a plurality of inwardly projecting walls spaced from each other along the periphery of the hub opening for permitting a drive shaft to have access to the hub.

Abstract: A magnetic recording disk cartridge is provided with an opening in its casing and a swingable erasing preventing unit inside the casing which can assume an open position in which a probe in the device in which the cartridge is used can enter the opening to detect that the cartridge is in an erasing prohibited condition or a closed position in which the probe is prevented from entering the opening to detect that the cartridge is in an erasing permitted condition. The erasing preventing unit has a detent which holds it in the open position until released by two coordinated actions and a lockarm which holds it in the closed position until pushed with the finger, thus precluding misoperation.