Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
1999-06-29
2001-04-10
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record medium
In container
C242S338300, C242S343000
Reexamination Certificate
active
06215619
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a tape cassette for recording and reproducing electric signals, and more particularly to a tape cassette which holds tape reels with a length of magnetic tape wound around and is equipped with a brake mechanism for stopping the motion of the reels.
PRIOR ART
Ordinarily, as described in Japanese Utility Model Application No. 4-67268, the tape reels contained in the housing of a tape cassette, with a length of tape wound around them, are engaged with spring-biased brake shoes and are unmovably locked in position when the cassette is not used. The brake shoes are operated by means of a release lever which is moved upward and downward by a release pin of a video tape recorder that is inserted from below the cassette housing. The upward and downward movement of the release lever is restricted by a coil spring. The coil spring that controls the release lever motion are engaged at one end with the release lever and at the other end with the inner surface of the upper casing so as to keep the coil spring in position and ensure good assembling efficiency.
This will be more concretely described with reference to
FIG. 1
illustrating a tape cassette of the invention (only the parts common to the prior art will be considered here) and also to
FIG. 11
which depicts a cassette of the prior art. As shown, the cassette housing consisting of upper and lower casings
1
,
2
holds a pair of tape reels
3
around which a length of tape
4
is wound. The tape is supplied from one reel through one of two openings formed at the front of the housing and is taken up via the other opening by the other reel. Lid members
5
,
6
are provided at the front of the housing in such a manner as to protect the tape portion exposed outside the housing body. The lower casing
2
is equipped with a brake mechanism which locks the tape reels
3
while the cassette is not in use.
The brake mechanism is composed of a pair of brake shoes
9
, a release lever
7
, a spring member
8
, and a pair of spring members
10
.
Each brake shoe
9
consists of an operating arm and a claw adapted to engage with a reel
3
and is provided with a hole for reception of a brake post
21
of the lower casing
2
. The brake shoes
9
are thus set on the brake posts
21
of the lower casing
2
, and torsion coil springs
10
are fitted to the upper ends of the brake shoes. The coiled portion of each torsion coil spring
10
is fitted to each brake post
21
and the two end portions of the spring are engaged with a brake shoe
9
and the lower casing
2
. The spring members
10
continually urge the claws of the brake shoes
9
in mesh with teeth
31
formed on the lower flanges of the tape reels
3
.
The release lever
7
has a contact surface
71
that comes in contact with the tapered operating arms of the brake shoes
9
, follower extensions
72
that are guided by guide walls of the lower casing
2
, and a cylindrical recess
73
for holding a spring member
8
. The release lever
7
is normally urged downward by the coil spring
8
that is in contact at the other end with the upper casing.
When the release lever
7
is forced upward by a brake release pin P of a VTR, its contact surface
71
comes in sliding contact with the tapered operating arms of the brake shoes
9
. This causes the brake shoes
9
to turn out of engagement with the teeth
31
of the tape reels
3
, allowing the reels
3
to turn freely.
As
FIGS. 9
show, the interior portion of the upper casing facing the portion of the lower casing
2
where the brake mechanism is installed, has a pair of cylindrical bosses
11
formed vertically from the inner wall. The bosses are designed to confine the coils of the torsion springs fitted to the upper ends of the brake posts
21
in position. There is no space provided between the holes at the lower ends of the cylindrical bosses
11
and the upper ends of the brake posts
21
, lest any deviation of the brake posts from the vertical should interrupt smooth turning of the brake shoes and bring an increased force for releasing the brake (beyond the specified value). The design also protects the torsion coil springs
10
and brake shoes
9
against disengagement due to vibration or impact and thereby prevents them from failing to function as a brake.
PROBLEM THAT THE INVENTION IS TO SOLVE
Assembling a cassette of the construction described above has presented a problem. In the course of assembling, one end of the coil spring
8
is engaged securely with the recess of the release lever
7
. However, when the upper casing
1
is mated with the lower casing, the opposite end of the coil spring
8
can sometimes be wrongly displaced, onto one of the cylindrical bosses
11
on reel brake posts
21
as shown in
FIG. 11
rather than onto the lug
12
with which it should normally engage as in FIG.
10
. If the two casings are joined as loaded with the coil spring
8
in the wrong position as illustrated in
FIG. 12
, the spring will no longer function as such. When the cassette is inserted into a VTR, the pin P of the latter forces the release lever
7
of the cassette upward. When the cassette is taken out, the coil spring
8
does not work properly, keeping the release lever
7
in the upward position. As a consequence, the reel brakes
9
remain released from the tape reels, and the unfettered reels allow the tape to loosen, eventually causing troubles such as the seizure of the tape by the lid members.
The present invention is therefore aimed at precluding the possibility that the coil spring that controls the upward and downward movement of the release lever in a tape cassette might be fitted in a wrong position within the upper half casing, and thereby preventing malfunctioning of the tape cassette.
The coil spring
8
is set in the release lever
7
by inserting the spring into the cylindrical recess
73
of the lever
7
. Positive engagement of the two parts is ensured, as shown in
FIG. 9
, by providing the cylindrical recess
73
with an annular support
75
having an adequate hollow for frictional engagement with the periphery at the lower end of the coil spring
8
and also providing a protuberance
12
on the inner wall of the upper casing to engage with the upper end of the coil spring
8
.
The annular support
75
formed in the release lever of the prior art is designed to surround the entire periphery of the spring. Dispersions in the manufacture of the annular support
75
and the spring
8
can sometimes provide a spring
8
with an outside diameter greater than the inside diameter of the support
75
. When this occurs, it is difficult to assemble the spring in place while keeping it circular with the reduction of the outside diameter of the coil portion at the lower end of the spring. In extreme cases the spring is set in place with its coil portion deformed elliptically and fitted in an inclined posture. Conversely if the coil portion is designed to be smaller in diameter than the support, the resulting gap is often too large to ensure a firm support.
The present invention, therefore, aims at providing a release lever which permits a spring member for controlling the upward and downward movement of the lever to be set in position simply and positively.
MEANS OF SOLVING THE PROBLEM
The above problem is solved by a tape cassette comprising a housing made up of upper and lower casings, a pair of reels around which a tape is wound and which are turnably contained in the housing, said lower casing holding reel brake shoes that control the rotation of said reels, torsion coil springs that control the turning of said reel brake shoes, and brake posts on which said reel brake shoes and said torsion coil springs are set, said upper casing having cylindrical bosses that cover the upper portions of said brake posts of said lower casing, said bosses being contiguous to reel area partition walls formed in the upper casing, said upper casing holding a release lever that turns said reel brake shoes, and a coil spring that restricts the movement of said release lever, chara
Kaneda Hiroshi
Okamura Masatoshi
Heinz A. J.
TDK Corporation
Wood Phillips VanSanten Clark & Mortimer
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