Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
1999-11-12
2001-09-18
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record medium
In container
Reexamination Certificate
active
06292331
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a tape cassette such as a digital video cassette which is used in a magnetic recording and reproducing apparatus, and more particularly to a tape cassette provided with an openable lid member in front of the cassette for protecting a tape medium.
In a conventional tape cassette of this type, a front lid having an L-shape in cross section is formed with a concave or a convex on its top plate, thereby to prevent a deflection of the front lid in a longitudinal direction caused by a shrinkage of a resin on occasion of injection molding (Post-examined Japanese Utility Model Publication 4-11271).
However, in case of the above described conventional tape cassette, even though the longitudinal deflection of the front lid can be prevented, side plates formed on opposite sides of the front lid and an upper lid constituting the lid member cannot be prevented from leaning due to the shrinkage of the resin.
Referring to
FIGS. 4A and 4B
, this leaning phenomenon will be explained.
FIG. 4A
is a bottom view of the front lid in the conventional tape cassette, and
FIG. 4B
is an enlarged view of a joint portion between the side plates and the front plate of the front lid. As shown in
FIG. 4A
, the front lid
41
includes a front plate
42
covering the front face of the tape and a top plate
43
extending from an upper edge of the front plate
42
in an almost right angle. At opposite ends of the front plate
42
and the top plate
43
having a cross section of an L-shape, are integrally formed side plates
45
provided with sub shafts
44
which act as rotating axes of the front lid when it is opened or closed.
As shown in
FIG. 4B
in an enlarged scale, the front plate
42
and the side plate
45
are formed thicker in areas adjacent to the joint portion P
1
therebetween than in other areas, because they constitute a corner zone, and thus, hardening after the injection molding proceeds more slowly at the joint portion than in surrounding areas. Accordingly, while the area adjacent to the joint portion P
1
is hardened, the front plate
42
and the side plate
45
which have already been hardened are pulled in directions of arrows (a) and (b) by a shrinking force of the resin. For this reason, the side plate
45
inclines in a direction of an arrow (c) to come into a position as shown by a two-dot chain line, so that the front plate
42
and the side plate
45
may not intersect at a right angle.
In case where the side plate
45
inclines in this manner so that the front plate
42
and the side plate
45
may not intersect at a right angle, the front lid
41
cannot be smoothly opened or closed when it is fitted to the case body to be opened or closed, because the sub shaft
44
inclines or an inner face of the side plate abuts on an outer side face of the case body. Moreover, the shrinking force exerted as described above when the resin is set is likely to create sink marks around the joint portion P
1
between the front plate
42
and the side plate
45
, which will degrade strength as well as an outer appearance of the tape cassette.
Although not specifically illustrated, the above described problem may occur not only in the front lid, but also in the upper lid which is adapted to be opened or closed in association with the front lid.
SUMMARY OF THE INVENTION
The present invention has been made in order to overcome the above described problem, and it is an object of the invention to provide a tape cassette in which the inclination of the front lid and the upper lid due to the hardening shrinkage on occasion of the injection molding, and an occurrence of the sink marks will be avoided.
In order to achieve the above described objects, the tape cassette according to the present invention comprises a case body for containing a pair of tape reels wound with a tape-shaped medium and an openable lid member provided in front of the cassette where the tape-shaped medium is exposed to an exterior, the lid member including a main plate and side plates formed at opposite sides of the main plate, characterized in that at least either one of the main plate and the side plate is made thinner in thickness in an area adjacent to a joint portion between the main plate and the side plate. Further, the lid member has a front lid or a front lid and an upper lid. The front lid includes a front plate as the main plate and the side plates formed at opposite sides thereof, while the upper lid includes a top plate as the main plate and the side plates formed at opposite sides thereof. The thinner area adjacent to the joint portion is preferably realized in a form of a slanted face or a concave.
With the described structure, the area adjacent to the joint portion between the front plate and the side plate of the front lid which constitutes the lid member and the area adjacent to the joint portion between the top plate and the side plate of the upper lid are made thinner in thickness than the other areas. Therefore, when the resin is set on occasion of the injection molding, the areas adjacent to the joint portions will be hardened earlier than the other areas. As a result, the side plates will not be pulled inwardly to be inclined as in the conventional case. Moreover, the sink marks which are likely to occur in the areas adjacent to the joint portions will be avoided, and thus the degradation of the strength and the outer appearance will be eliminated.
REFERENCES:
patent: 4893766 (1990-01-01), Yamashina et al.
patent: 5654855 (1997-08-01), Iwano et al.
patent: 4-011271 (1992-03-01), None
Kaneda Hiroshi
Momoi Akio
Okamura Masatoshi
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
TDK Corporation
Tupper Robert S.
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