Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
2000-11-15
2004-04-06
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Record medium
In container
Reexamination Certificate
active
06717771
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a one-reel magnetic tape cartridge for use in a computer or the like.
BACKGROUND OF THE INVENTION
As a backup medium for a computer memory, there has been known a magnetic tape cartridge comprising a thin rectangular cartridge casing formed of upper and lower halves fixed together by screws or the like and a single reel which is housed in the cartridge casing for rotation and around which a magnetic tape is wound.
When such a magnetic tape cartridge is loaded in a recording and reproducing apparatus, a drive member of the apparatus is engaged with engagement teeth on the reel exposed through a circular opening formed on the lower half of the cartridge casing at the center thereof and the magnetic tape wound around the reel is drawn out from the cartridge casing into a predetermined position on the tape running path by a tape drawing mechanism of the apparatus, whereby read/write of data becomes feasible.
In such magnetic tape cartridges, conventionally, a projection for stacking is formed on the upper surface of the cartridge casing of each magnetic tape cartridge and a recess for stacking is formed on the lower surface of the cartridge casing of each magnetic tape cartridge so that, when a plurality of magnetic tape cartridges are stacked, the recess for stacking on one magnetic tape cartridge is engaged with the projection for stacking on the upper magnetic tape cartridge, whereby the relative position between the upper and lower magnetic tape cartridges is fixed so that a plurality of magnetic tape cartridges can be transported in a stacked state.
Conventionally, the projection for stacking on the lower surface of the cartridge casing is generally in the form of a pair of protrusions which extend in the direction of insertion of the magnetic tape cartridge into the recording and reproducing apparatus on opposite sides of the circular opening. This arrangement gives rise to a problem that the protrusions are apt to warp and when they warp, the protrusion on each magnetic tape cartridge cannot be stably engaged with the engagement recess of the lower magnetic tape cartridge when a plurality of magnetic tape cartridges are stacked, whereby the magnetic tape cartridges become shaky.
Further, there has been also a problem that the protrusions increase sliding friction when the magnetic tape cartridge is inserted into the recording and reproducing apparatus.
In the magnetic tape cartridge, locator holes for locating the magnetic tape cartridge with respect to the recording and reproducing apparatus are often provided in the bottom wall of the lower half of the cartridge casing. In such a case, bosses each provided with a locator hole extending through the boss are formed on the bottom wall of the lower half at its four corners together with bosses each provided with through holes through which a screw for fastening together the upper and lower halves of the cartridge casing is inserted.
Further, a tape draw-out opening through which the magnetic tape in the cartridge casing is drawn out is formed in the side wall of the cartridge casing near one corner thereof, and a taper leader member is removably held in a space open to the tape draw-out opening between the lower surface of the top wall of the upper half and the upper surface of the bottom wall of the lower half. Accordingly, the tape draw-out opening must be provided with a space for accommodating the tape leader member, a space through which the magnetic tape runs and a space through which a tape draw-out member on the recording and reproducing apparatus is given access to the tape leader member, which greatly limits the space near the tape draw-out opening in which bosses can be provided.
Further, since a circular rib which coaxially surrounds the reel is erected from the upper surface of the bottom wall of the lower half, the space near the tape draw-out opening in which bosses can be provided is further limited and accordingly, the bosses for the locator holes and the screw holes and the circular rib must be provided in contact with each other or close to each other.
However, when the bosses and the rib are formed in contact with each other or close to each other, the part is locally thickened, which makes it difficult to keep a sufficient dimensional accuracy and geometric accuracy of the locator holes when the cartridge casing is molded due to nonuniform cooling in the mold and difference in shrinkage factor. Further, the bosses, the holes and the rib become apt to lean.
Further, when there exists a part at which the wall thickness is extremely large as compared with other parts, there arises fear that sink marks and/or welding lines are generated on the inner surface of the locator hole and the locator hole is disabled from functioning as a locator.
Further, even in the case where the bosses and the rib are in contact with each other but are simply close to each other, the part of the wall of the mold between parts which are close to each other is less apt to be cooled as compared with other parts, and accordingly, it is difficult to keep a sufficient dimensional accuracy and geometric accuracy and the bosses, the holes and the rib become apt to lean.
Further, the magnetic tape cartridge is generally provided with a brake member which locks the reel not to rotate when the magnetic tape cartridge is not being used and a coiled spring which urges the brake member in the direction of the axis of rotation of the reel. Generally the cartridge casing is formed by plastic injection molding. The urging force of the coiled spring can deform outward the top wall and/or the bottom wall of the cartridge casing. When the top wall and/or the bottom wall of the cartridge casing is deformed outward, the cartridge casing can interfere with the reel to obstruct rotation of the reel, location of the magnetic tape cartridge with respect to the recording and reproducing apparatus can become infeasible and/or stacking of the magnetic tape cartridges can be adversely affected.
In order to overcome these problems, the cartridge casing has been formed by molding of a glass-fiber reinforced polycarbonate resin or the like so that the rigidity of the cartridge casing is increased and deformation of the cartridge casing is prevented.
However this approach has been disadvantageous in that the service life of the molds is shortened and wear of the bucket of the recording and reproducing apparatus is increased when the magnetic tape cartridge is loaded in or unloaded from the recording and reproducing apparatus. That is, use of glass fiber reinforcement is not preferred from these viewpoints.
Though the plastic injection molding is useful as a technique for accurately and efficiently forming products of a complicated shape, it gives rise to a problem that a gate mark is left on the surface of the products which can obstruct loading and unloading of the magnetic tape cartridge in and from the recording and reproducing apparatus and can be ground to produce plastic grindings during loading and unloading of the magnetic tape cartridge depending on the position of the gate mark.
When a desired magnetic tape cartridge is taken out from a library and loaded in a recording and reproducing apparatus by a chucking machine or when the magnetic tape cartridge is taken out from the recording and reproducing apparatus and returned to the library by the chucking machine, the gate mark sometimes obstructs stable chucking of the magnetic tape cartridge.
Though these problems can be avoided by disposing the gate in a recess of the surface of the cartridge casing, flow of the resin near the gate becomes low since the wall thickness near the gate becomes smaller due to existence of the recess. As a result, uneven packing of resin is generated near the gate, the end of the flow (e.g., side walls) can sink to deteriorate the dimensional accuracy and, at the worst, short molding can occur due to a poor packing pressure. Though these problems can be avoided by providing a plurality of gates, the approach adds to the cost a
Childers Ed
Heinze Robert Ralph
Ishihara Yusuke
McAllister Jeffrey S.
Morita Kiyoo
Beacham C. R.
Ometz David L.
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