Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
2002-06-27
2004-05-18
Rivera, William A. (Department: 3654)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
C242S343000, C242S611100
Reexamination Certificate
active
06736345
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording tape cartridge for rotatably accommodating a reel on which a recording tape is wound.
2. Description of the Related Art
In a conventionally known type of recording tape cartridge for a recording medium for use as an external storage device of a computer or the like, a single reel, on which a recording tape such as a magnetic tape is wound, is rotatably accommodated in the recording tape cartridge.
A magnetic tape is used, for example, for storing computer data. The tape cartridge is structured so as to prevent the magnetic tape, which may contain important information, from jamming or the like, and from being unwound unintentionally when not in use, such as during storage or the like.
The reel comprises a reel hub and upper and lower flanges, which are disposed at both ends of the reel hub. As shown in
FIG. 29
, a reel hub
500
and a lower flange
502
are integrally molded and, after the molding, an upper flange
504
is welded to the reel hub
500
to form a reel
506
.
A magnetic tape can be wound on the reel hub
500
, and width-directional end portions of the wound-on magnetic tape are retained by the upper and lower flanges
504
and
502
.
As shown in
FIGS. 29 and 30
, the reel hub
500
is provided with a driven gear
508
, which meshes with a driving gear for transmitting driving force from a drive-side driving device (not shown).
At an inner side of the driven gear
508
is disposed a metal plate
510
for magnetic attachment. The metal plate
510
is magnetically attracted by a magnet disposed at the drive-side driving device, thus preventing misalignment of the axis and keeping the meshing state of the driven gear
508
and the driving gear. However, because the reel hub
500
is provided with the driven gear
508
, the metal plate
510
, and the like, variations of pressure during the molding may affect the lower flange
502
molded integrally with the reel hub
500
, reducing flatness of the lower flange
502
, and this may be a cause of surface-runout in the drive. Further, because the flatness of the lower flange
502
is lowered, roundness of the reel hub
500
deteriorates.
The metal plate
510
is integrally molded with the reel hub
500
and the lower flange
502
inside a metal mold which molds the reel hub
500
and the lower flange
502
. Three through-holes
512
for joining the metal plate
510
to the reel hub
500
are formed at regular intervals in the metal plate
510
on a concentric circle thereof. During molding, a molding material flows into the through-holes
512
to fix the metal plate
510
to the reel hub
500
.
In the metal mold, a position corresponding to an inner circumferential portion of the reel hub
500
is a gate position. When the reel hub
500
and the lower flange
502
are molded, the molding material flows in a space defined by the metal mold from the position corresponding to the inner circumferential portion of the reel hub
500
towards positions corresponding to a distal portion of the reel hub
500
, and in radial directions towards positions corresponding to an outer circumferential portion of the lower flange
502
.
When the molding material flows into the through-holes
512
formed in the metal plate
510
, air in the through-holes
512
causes friction that resists the molding material. Therefore, comparing with a case in which the molding material flows around the metal plate
510
, the pressure is increased. This causes variations in the pressure in a cavity
516
, and disturbs stress balance.
Because the stress balance is disturbed when the molding material is filled, the disturbed stress balance is manifested as residual stress after the molding, and causes deformation of the reel hub
500
and the lower flange
502
shown in FIG.
29
. Therefore, there is a risk of lowering the accuracy of the reel hub
500
and the driven gear
508
, and the flatness of the lower flange
502
.
Further, as shown in
FIG. 31
, because within the through-hole
512
(shown by arrows) moves during hardening of the molding material, wrinkles
518
are produced. Particularly, if the wrinkles
518
produce differences in the level of the outer circumferential surface of the reel hub
500
(see FIG.
29
), a winding state of the magnetic tape on the reel may be disturbed, and magnetic surfaces at the inner and outer circumferential sides of the magnetic tape may be scratched by the tape's edges.
SUMMARY OF THE INVENTION
In view of the aforementioned, an object of the present invention is to provide a recording tape cartridge comprising a highly accurate reel including highly flat flanges. Further, there is a demand for improving breaking power of the reel.
In a first aspect of the present invention, a single reel, on which a recording tape is wound, is rotatably accommodated in a recording tape cartridge. The reel includes a hollow hub on which the recording tape is wound. Annular flanges are disposed at both ends of the hub for holding width-directional ends of the recording tape wound on the hub. Also, a metal plate is inserted at one end of the hub.
The hub is formed such that cross-sections taken radially from an axis thereof are the same as each other. This makes flowing states of a molding material the same for the respective cross-sectional directions. Therefore, the flowing state of the molding material does not differ with circumferential position.
In the first aspect of the present invention, an annular joining device that joins to an outer circumference of the metal plate may be provided at the hub. By joining the outer circumference of the metal plate inserted at the end of the hub using the annular joining device, cross-sections of the hub, taken radially from the axis thereof, can be made the same as each other.
Further, since there is no need to provide a hole or the like in the metal plate, variations in the pressure of the molding material flowing over the metal plate are small. Therefore, residual stress can be reduced, thereby improving accuracy of the hub and flatness of the flange.
Furthermore, by joining the metal plate firmly at the outer circumference thereof, the internal dimensions of a portion for joining the metal plate is increased compared with the case in which the metal plate is provided with holes. This means air is easier to remove and less likely to stay. Thus, no wrinkles are created on the hub and the flange.
In the first aspect of the present invention, the joining device may include a joining portion provided at the end of the hub. The joining portion surrounds an annular joined portion extending from an entire outer circumference of the metal plate, and joins the same.
In the present invention, the joining portion may be an annular pawl portion that holds the joined portion. By provision of the pawl portion, the metal plate is prevented from coming off.
In the present invention, the joined portion may join by projecting toward a side away from the pawl portion and meshing with the hub. Thus, the metal plate is firmly fixed to the hub.
In the present invention, an annular fitting portion can be provided in a metal mold for molding the hub, and an annular fitting portion, which fits to the fitting portion of the mold can be formed at the metal plate. Thus, the metal plate is assuredly fixed in the metal mold.
In a second aspect of the present invention, a recording tape cartridge rotatably accommodates a reel on which a recording tape is wound, and the reel includes a hollow hub on which the recording tape is wound. Flanges are welded at both ends of the hub, and the flanges retain the width-directional ends of the recording tape that is wound on the hub.
Specifically, the hub and the flanges are separately molded, and the flanges are then welded at the both ends of the hub to form the reel. Separately molding the hub and the flanges allows selection of a suitable gating system, for example disc gates, and setting of optimal molding conditions for each shape.
Therefore, compared with the case i
Hiraguchi Kazuo
Morita Kiyoo
Fuji Photo Film Co. , Ltd.
Rivera William A.
Sughrue & Mion, PLLC
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