Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
2001-04-26
2002-10-29
Nguyen, John Q. (Department: 3654)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
C360S132000, C267S158000, C267S160000
Reexamination Certificate
active
06471151
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a reel spring of a magnetic tape cassette for forcing in a direction to a reel around which a magnetic tape is wound and which is rotatably provided in a cassette case. The present invention also relates to a magnetic tape cassette using the reel spring.
BACKGROUND ART
In audio set equipment, video set equipment or the like, a magnetic tape cassette which allows a magnetic tape wound around a pair of reels to run in a cassette case to perform recording and replaying has generally been used.
In such magnetic tape cassette, a pair of reel springs are provided in the cassette case to prevent the pair of reels around which a magnetic tape is wound from displacing in an axial direction of rotation and to allow the tape to run smoothly whereupon the pair of reels are forced on in the axial direction of rotation in the cassette case by the pair of reel springs each other.
FIG. 3
shows a part of a digital video cassette L type (DVC-L) as a digital video cassette for business use which has such reel springs.
As shown in
FIG. 3
, the digital video cassette
30
comprises an upper half
32
of a cassette case, a pair of reels
34
around which a magnetic tape is wound and which are rotatably provided in the cassette case and a pair of reel springs which are each a flat plate in an approximately rectangular shape having a bending portion in a midway in a longitudinal direction to form an L-like shape, as well as other members not shown in the figure such as a lower half as a part of the cassette case, an outer lid, an upper lid and an inner lid which constitute a lid to cover an opening in the front of the cassette case, various springs and the like.
The reel spring
36
, as shown in
FIGS. 4A and 4B
, has a fixing portion
36
a
which is fixed to the cassette case to form a fixing end, an arm portion
36
b
which forces on the aforementioned reel in the axial direction of rotation and a bending portion
36
c
provided between the fixing portion
36
a
and the arm portion
36
b.
The fixing portion
36
a
has a boss hole
46
. The boss hole
46
is provided so as to fix the reel spring
36
to a reel spring provision portion
40
which is provided in the upper half
32
of the cassette case shown in FIG.
3
.
An end of the reel spring
36
is chamfered off in a triangular shape and the other end thereof in a circular shape.
A length of the arm portion
36
b,
namely a length from the bending portion
36
c
to an edge of the arm portion
36
b,
is needed to be long within an extent enough for keeping an urging force consistently, for reducing variation of the urging force by device of a variation of dimension of the reel spring
36
inherent to mass production of reel spring
36
which forces a reel
34
with a specified urging force, exemplified by a variation of bending angel of bending portion
36
c.
Moreover, ratio of a length of the fixing portion
36
a,
which is defined by a length from the bending portion
36
c
to an edge of the fixing portion
36
a,
to the length of the arm portion
36
a
is preferred to be larger within an extent enough for keeping the specified urging force consistently, though not necessarily being over 1.0, because of preventing the fixing portion
36
a
which should be in contact with a bottom surface of the upper half
32
from being deformed and partially lifted when the reel spring
36
forces on the reel
34
, as shown in FIG.
5
. Therefore, the length of the arm portion
36
b
is designed to be longer than that of the fixing portion
36
a,
for example 5 mm longer.
The diameter of the boss hole
46
of the fixing portion
36
a
is formed larger than that of an upper half boss
42
so that, when the reel spring
36
is provided to a reel spring provision portion
40
, it gets regulated in a lateral direction by reel spring provision portion guides
44
and the reel spring is easily engaged with the upper half boss
42
of the upper half
32
.
When the digital video cassette
30
is assembled, such reel spring
36
is provided to the reel spring provision portion
40
of the upper half
32
by reel spring supply device not shown in the figure, is regulated in the lateral direction by reel spring provision portion guides
44
and mounted in a manner that the boss hole
46
is engaged with the upper half boss
42
on the upper half
32
. Thereafter, the reel spring
36
is transported to a welding step of a cassette assembly line in which a top of the upper half boss
42
engaged with the boss hole
46
of the reel spring
36
is melted and the reel spring is welded to the upper half
32
.
In this occasion, as described above, in order to prevent the fixing portion
36
a
of the reel spring
36
welded to the upper half
32
from being deformed and partially lifted from the bottom surface of the reel spring provision portion
40
(see FIG.
5
), the length of the arm portion
36
b
is designed longer than that of the fixing portion
36
a
so that the arm portion
36
b
contacts the bottom surface of the reel spring provision portion
40
in relation with a position of the gravity center and, accordingly, the fixing portion
36
a
comes to be in a lifted state. However, in a case in which the digital video cassette is a small-sized one for private use (DVC-S type) where a ratio of the length of the fixing portion
36
a
to a height of the upper half boss
42
is less than 4.0, as shown in
FIG. 6
, the boss hole
46
of the fixing portion
36
a
is not released (disengaged) from the upper half boss
42
of the upper half
32
so that problems such as complexity of welding operation or of transportation operation, decrease of assembling work efficiency and so forth do not occur.
In contrast, in another case in which the digital video cassette is a large-sized one for business use where the ratio is 4.0 or more as L type (DVC-L), the reel spring
36
should be longer longitudinally in accordance with the size of the digital video cassette and. As a result, when the length of the reel spring
36
comes to be longer, the length of the arm portion
36
b,
as well as that of the fixing portion
36
a,
becomes longer even if the ratio of the arm portion
36
b
to the fixing portion
36
and the bending angle of the bending portion
36
c
are not changed so that, even when the fixing portion
36
a
of the reel spring
36
is mounted on the reel spring provision portion
40
in a manner that the upper half boss
46
of the upper half
32
is engaged with the boss hole
46
of the reel spring
36
, as shown in
FIG. 7
, the boss hole
46
of the fixing portion
36
a
is likely to be released from the upper half boss
42
on the upper half
32
. Therefore, during the transportation to the welding step, instead of being laterally regulated with the reel spring provision portion guides
44
, the reel spring
36
bounces or slides in a disposal direction either of the right or left ridge of the reel spring provision portion guides
44
, by vibration or the like to be dislocated from the appropriate position. Moreover, a trouble occurs in a welding operation in that, at the time of welding, the welding operation must be performed by pressing the fixing portion
36
a
down to the bottom surface of the reel spring provision portion
40
so that it may not be lifted up.
To cope with these problems, it is conceivable to provide a device to press down the reel spring
36
so that the reel spring
36
may not be dislocated from the reel spring provision portion
40
during the transportation. However, this causes transportation operation complicate.
Even if the device which presses down the reel spring
36
is provided during the transportation to allow the reel spring
36
to remain in an appropriate position, it is necessary to weld the upper half boss
42
with an ultrasonic welder or the like while keeping the reel spring
36
in a specified set condition preventing the fixing portion
36
a
from being lifted up at the welding step. This causes to complicate welding step as well as welding operation at the welding step t
Kita Akihisa
Yamaguchi Tatsuya
Nguyen John Q.
Sughrue & Mion, PLLC
LandOfFree
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