An object of the present invention is to provide a cassette shutter in which the durability of a curved shutter for opening and closing a medium entrance of a cassette is improved, and assembly of parts is simple. In the present invention for achieving said objective, a cassette shutter, which is slidably disposed on front and bottom surfaces of a cassette storing a paper medium therein and opens and closes an entrance formed in the front surface of the cassette, is configured to include: a plurality of pieces arranged longitudinally and a fastening pin that passes through and thereby fastens a lower portion of an upper-side piece and an upper portion of a lower-side piece so as to enable relative rotation of the plurality of pieces.

A magnetic tape cartridge includes: a magnetic tape on which data is recorded; and a recording medium other than the magnetic tape, and on which a keyword for searching the data recorded on the magnetic tape is recorded.

A tape-type magnetic recording medium, includes a substrate; and a magnetic layer provided on the substrate. The magnetic recording medium is configured such that (1) (w.sub.max−w.sub.min)/w.sub.min≤400 [ppm] where w.sub.max and w.sub.min are respectively maximum and minimum of average values of width of the magnetic recording medium measured under four environments whose temperature and relative humidity are (10° C., 10%), (10° C., 80%), (29° C., 80%), and (45° C., 10%), respectively, and the magnetic layer has a squareness ratio of 65% or more in the vertical direction, and (2) 4.4≤T.sub.B/(T.sub.A−T.sub.B) where T.sub.A is an average thickness of the magnetic recording medium and T.sub.B is an average thickness of the substrate.

A mover replacement system for removing a media mover, movable between an operating position and a removable position, from within a media library includes a module housing and a service tray. The module housing forms at least a part of a library housing. The service tray is removably positionable within the module housing. The service tray is configured to releasably retain the media mover when the media mover is in the removable position so that the service tray and the media mover are movable as an integral unit out of and into the module housing. The service tray includes a tray body and at least one locking mechanism that is movable relative to the tray body between a retracted position when the at least one locking mechanism is positioned not to engage the media mover, and a fully extended position when the at least one locking mechanism is positioned to retain the media mover relative to the tray body.

A base plate is a portion of a housing of a hard disk drive, and includes a cast base body. The base body includes an inner surface including an inside machined surface that is machined and an inside non-machined surface that is not machined. The base body includes an outer surface including an outside machined surface that is machined and an outside non-machined surface that is not machined. The outside machined surface and the inside non-machined surface overlap in an axial direction that is a direction parallel or substantially parallel to a rotation axis of a disk of the hard disk drive.

The disc device comprises disc selector spindle that hold discs in a stacked state, separate lowermost disc from other discs, and supply separated lowermost disc to drive unit. The disc selector spindle includes first, second, and third support claws that move to storage position at which each support claw is stored inside center hole of disc and protrusion position at which each support claw protrudes in a region located in the vicinity of inner diameter of disc in plan view. First support claw moves to storage position and protrusion position independently of the movements of second support claw and third support claw. Second support claw is disposed so as to be shifted from third support claw in a stacking direction of disc by a thickness of one disc, and to move from storage position to protrusion position at a timing different from a timing of third support claw.

A disc storage device rack includes: an accommodation space surrounded by left and right side plates and upper and lower partition plates and configured to accommodate a disc storage device; a guide portion provided on the side plates and configured to fit to a guided unit provided in the disc storage device to guide a sliding operation of the disc storage device; and a shutter provided on each end surface of the side plates so as to be slidable in an up-and-down direction and configured to open an opening of the guide portion when the disc storage device is pulled out from the accommodation space or when the disc storage device is pushed into the accommodation space.

A disc storage device rack includes: an accommodation space surrounded by left and right side plates and upper and lower partition plates and configured to accommodate a disc storage device; a guide portion provided on the side plates and configured to fit to a guided unit provided in the disc storage device to guide a sliding operation of the disc storage device; and a shutter provided on each end surface of the side plates so as to be slidable in an up-and-down direction and configured to open an opening of the guide portion when the disc storage device is pulled out from the accommodation space or when the disc storage device is pushed into the accommodation space.

The disc device comprises disc selector spindle that hold discs in a stacked state, separate lowermost disc from other discs, and supply separated lowermost disc to drive unit. The disc selector spindle includes first, second, and third support claws that move to storage position at which each support claw is stored inside center hole of disc and protrusion position at which each support claw protrudes in a region located in the vicinity of inner diameter of disc in plan view. First support claw moves to storage position and protrusion position independently of the movements of second support claw and third support claw. Second support claw is disposed so as to be shifted from third support claw in a stacking direction of disc by a thickness of one disc, and to move from storage position to protrusion position at a timing different from a timing of third support claw.

A tape-type magnetic recording medium, includes a substrate; and a magnetic layer provided on the substrate. The magnetic recording medium is configured such that (1) (w.sub.maxw.sub.min)/w.sub.min400 [ppm] where w.sub.max and w.sub.min are respectively maximum and minimum of average values of width of the magnetic recording medium measured under four environments whose temperature and relative humidity are (10 C., 10%), (10 C., 80%), (29 C., 80%), and (45 C., 10%), respectively, and the magnetic layer has a squareness ratio of 65% or more in the vertical direction, and (2) 4.4T.sub.B/(T.sub.AT.sub.B) where T.sub.A is an average thickness of the magnetic recording medium and T.sub.B is an average thickness of the substrate.