Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
2000-08-04
2003-02-04
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Record medium
In container
C242S343000
Reexamination Certificate
active
06515828
ABSTRACT:
TECHNICAL FIELD
This invention relates to a magnetic tape cassette comprising reels on which a magnetic tape is wound, and a reel lock member which is engageable with the teeth of the reels.
BACKGROUND ART
Magnetic tape cassettes are popularly employed as recording media.
FIG. 7
is an exploded perspective view of a DVC (digital video cassette), namely, a magnetic tape cassette
20
.
As shown in
FIG. 7
, the magnetic tape cassette
20
comprises a cassette body, a magnetic tape (not shown) and an opening and closing lid
27
. The cassette body comprises opening
21
an upper cassette half
22
and a lower cassette half
23
. In front portion of the cassette body (left side in FIG.
7
), the cassette body possesses opening
21
for inserting a tape pull-out member equipped in a video tape recorder (VTR). The magnetic tape (not shown) is laid tight in the opening
21
with the aid of tape guides
37
and
38
which are provided on the front surface of the cassette body. The opening and closing lid
27
is provided on the front of the cassette body, and comprises an outer lid (or front lid)
29
, a top lid (or upper lid)
30
and an inner lid (or rear lid)
31
.
In the lower cassette half
23
, a pair of reels
35
and
36
are rotatably provided and a magnetic tape is wound on the reels
35
and
36
. The reels
35
and
36
comprise disk-shaped upper flanges
39
and
40
and disk-shaped lower flanges
41
and
42
. The disk-shaped lower flanges
41
and
42
are integrally molded with cylindrical hubs
41
a
and
42
a
, and have engaging teeth
43
and
44
along the whole peripheries thereof, respectively.
When the magnetic tape cassette
20
is not loaded in a device such as a VTR, i.e., when the cassette is stored or carried, the magnetic tape has the possibility to be slackened. In order to prevent the magnetic tape from being slackened, a reel lock member
45
and a lock spring
46
are provided. The reel lock portion
45
is provided in the space formed on the rear side of the cassette and between the reels
35
and
36
, and functions to prevent the rotation of the reels
35
and
36
. The lock spring
46
is provided and adapted to urge the reel lock member
45
.
On the other hand, recently there has been a strong demand for an increase in recording capacity. However, the outer dimensions of the cassette body cannot be increased so much because of the dimensional limits of the hardware side. Therefore, the following method has been employed: the hub diameter of the reels, on which the magnetic tape is wound, is decreased in diameter, and the flange diameter of the reels is increased, while the reel accommodating area of the cassette half which is adapted to accommodate the reels is increased. For instance, as shown in
FIG. 8
, the reel accommodating areas
50
of the lower half
23
are made larger than those of the prior art according to the large diameter reels
35
a
of which flange diameter d
1
is larger.
FIG. 9
is an exploded diagram of the lower half
23
a
which accommodates reels
35
b
having an ordinary flange diameter d
2
, showing only the left reel for simplification in description. As shown in
FIG. 9
, in order to stop the rotation of the reel
35
b
, the engaging pawls
45
a
of the reel lock member
45
are engaged with the engaging teeth
43
b
of the reels
35
b
. However, since the reel accommodating area
50
is formed according to the large diameter reel
35
a
the flange of which is large in diameter, as shown in
FIG. 10
, when the cassette is dropped or vibrated the reel
35
b
having the ordinary flange diameter may be shifted to the front and to the side, or leave a track. Then, as shown in
FIG. 11
, when it is intended to stop the rotation of the reel, the engaging pawl
45
a
of the reel lock member
45
cannot engage with the engaging teeth
43
b
of the reel
35
b.
DISCLOSURE OF THE INVENTION
In view of the foregoing, an object of the invention is to provide a magnetic tape cassette in which, regardless of the outside diameter of the reels accommodated therein, the rotation of the reels can be positively stopped.
The above-mentioned object can be achieved by a magnetic tape cassette comprising:
a reel on which a magnetic tape is wound and which turns on a predetermined track and has an engaging teeth at its periphery;
a cassette half having a reel accommodating area which is accommodatable various kind of reels which are different in an outside diameter from one another;
a reel lock member disposed on the cassette half and having an engagement pawl, the reel lock member being slidable between a reel lock position where the engagement pawl of the reel lock member is engaged with the engaging teeth of the reel so as to inhibit a rotation of the reel and a releasing position where the reel lock member disengages from the engaging teeth of the reels so as to allow the rotation of the reel; and
a rib disposed on the cassette half for keeping a locking condition where the engagement pawl is engaged with the engaging teeth, when the reel leaves from the predetermined tracks.
In the above construction of the magnetic tape cassette according to present invention, it is preferable that the rib is substantially confronted with a tip end of the engagement pawl about a center of the reel.
In the above construction of the magnetic tape cassette according to the present invention, it is preferable that the shortest distance defined between the rib and the tip end of the engagement pawl of the reel locking member, which is located in the reel lock position, is shorter than the outside diameter of the reel.
In the above construction of the magnetic tape cassette according to present invention, it is preferable that the engagement pawl is extended in a line, and the rib is substantially disposed on the line.
Further, in the above construction of the magnetic tape cassette according to present invention, it is preferable that the cassette half is formed by injection molding with a main metal mold, and the rib is formed by injection molding with an insert mold which is attachable to the main metal mold.
The above-mentioned object can be also achieved by a metal mold, according to a present invention, used for manufacturing a magnetic tape cassette including,
a reel on which a magnetic tape is wound and which turns on a predetermined track and has a engaging teeth at its periphery,
a cassette half having a reel accommodating area which is accommodatable various kind of reels which are different in its outside diameter,
a reel lock member disposed on the cassette half and having an engagement pawl, the reel lock member being slidable between a reel lock position where the engagement pawl of the reel lock member is engaged with the engaging teeth of the reel so as to inhibit a rotation of the reel and a releasing position where the reel lock member disengages from the engaging teeth of the reels so as to allow the rotation of the reel, and a rib disposed on the cassette half for keeping a locking condition where the engagement pawl is engaged with the engaging teeth, when the reels leave from the predetermined tracks,
the metal mold comprising:
a main metal mold portion forming the cassette half by an injection molding; and
an insert metal mold portion being attachable to the main metal mold portion for forming the rib by the injection molding simultaneously.
According to the invention, even with a cassette half having a reel accommodating area in correspondence to maximum diameter reels, when the reel accommodated therein leaves the track, the rib provided in the reel accommodating area regulates the position of the reel to the reel lock position, so that the reel lock member stops the rotation of the reel. Accordingly, even when the cassette for instance drops to cause the reel leave the track, the rotation of the reel can be positively stopped, and accordingly the magnetic tape will never be slackened.
Furthermore, in the magnetic tape cassette, a part of a metal mold adapted to form the cassette half by injection-molding which is to form the rib is
Evans Jefferson
Fuji Photo Film Co. , Ltd.
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