Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
2002-09-20
2003-04-29
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record medium
In container
C264S446000
Reexamination Certificate
active
06556379
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic tape cassette characterized by a window frame structure of a magnetic tape cassette having a window member for confirming the winding amount of the magnetic tape, a window member, and a resin product.
Generally, in audio devices and video devices, a magnetic tape cassette is used very much, in which recording and playing operations are performed while a magnetic tape wound onto a pair of tape reels is being held within the cassette case so that it can run.
As shown in
FIG. 6
, for example, a magnetic tape cassette
50
used for DVC (digital video cassette) has a cassette case which is constituted by upper and lower halves
51
,
52
. Their upper and lower halves
51
,
52
are fitted to each other and tightened by a plurality of screws. And, a pair of tape reels
53
,
53
formed by welding an upper flange and a hub with which a lower flange is integrally formed are rotatably stored in the cassette case in a state where a magnetic tape
52
is wound onto the tape reels.
Tape guides
55
,
55
are provided on both sides of an opening portion
56
on a front-end side in the lower half
52
. Each tape guide
55
guides the magnetic tape
57
that is fed out from one tape reel
53
and wound onto the other tape reel
53
, and causes the magnetic tape
57
to pass through the predetermined position in the opening portion
56
.
Further, on a rear end side of the lower half
52
, a tape reel lock member
58
having a tape reel fixing arm
58
a
is incorporated. The tape reel lock member
58
is energized by a compressive coil spring
59
, whereby the tape reel fixing arm
58
a
is fitted to fitting teeth
53
a
formed on the periphery of the lower flange of each tape reel
53
thereby to prevent unexpected rotation of each tape reel
53
. Hereby, looseness of winding of the magnetic tape
57
is prevented.
Further, a reel energizing plate spring
63
is attached to a top plate
51
a
of the upper half
51
in relation to each tape reel
53
. Each reel energizing plate spring
63
is overhung by the upper half
51
and energizes the corresponding tape reel
53
on the lower half
52
side.
Further, an outer lid
60
, a top lid
61
and an inner lid
62
which cover a front surface and a rear surface of the magnetic tape
57
laid between a pair of the tape guides
55
in the lower half
52
are openably and closeably attached on the front end side of the upper half
51
in order to obtain dustproof ability with which the tape cassette is fit for outdoor use.
On one side (on right side in the figure) in the longitudinal direction of the top plate
51
a
of the upper half
51
in this magnetic tape cassette
50
, a window opening
65
which extends in the short direction of the top plate
51
a
is formed so that the winding amount of the magnetic tape
57
(residual amount) onto the tape reel
53
can be confirmed. And, a transparent window member
64
is attached so as to close the window opening
65
.
As shown in
FIG. 7
, the window member
64
formed substantially in the shape of a hexagon has a plurality of welded ribs
66
on a fixed surface
64
a formed at the periphery of the window member. On the other hand, at the periphery of the window opening
65
formed in the top plate
51
a
of the upper half
51
, a fixing surface
65
a
for fixing the window member
64
thereto is formed. The thickness of the portion where its fixing surface
65
a
is formed is made thinner than that of the top plate
51
a
. The fixing surface
65
a
continues to the surface of the top plate
51
a
through a slant
67
. Further, at a portion surrounding the fixing surface
65
a
, positioning ribs
68
are formed on each side of the window opening
65
. Further, since a corner portion B that is a part of the portion surrounding the fixing surface
65
a
is located immediately below the overhung end portion of the reel energizing plate sprint
63
, it is a flat surface that continues to the surface of the top plate
51
a
but not the slant.
In order to attach this window member
64
onto the upper half
51
, the window opening
65
is firstly covered with the window member
64
while the window member
64
is being guided by the positioning ribs
68
, and the welded ribs
66
of the window member
64
are placed onto the fixing surface
65
a
of the peripheral portion of the window opening
65
. Then, in a state where the window member
64
is pressed against the fixing surface
65
a
of the peripheral portion of the window opening
65
, the welded ribs
66
of the window member
64
are welded onto the fixing surface
65
a
by ultrasonic vibration or the like, as shown in FIG.
8
.
On the other hand, the fixing surface
65
a
onto which the window member
64
of the upper half
51
is welded has a difference-in-level in relation to the surface (inner surface or outer surface) of the top plate
51
a
. In case that the thickness changes suddenly at the portion of this difference-in-level, crape transfer defect is produced due to a reason why time for which the pressure is applied is different at the injection molding time or other reasons, so that there is fear that the appearance of the surface of the upper half
51
will be damaged. Such crape transfer defect means that a crape surface is not formed on a portion of the external surface on the cassette or the product.
Therefore, in the upper half
51
, as described above, the fixing surface
65
a
continues to the surface of the top plate
51
a
through the slant
67
, whereby the sudden change of the pressure at the injection molding time is avoided and the bad appearance of the upper half is prevented.
However, in the cassette case adopting the window frame structure like this, when an external force is applied onto the window member
64
, it acts concentratedly on a corner portion C on the opening portion side through which the magnetic tape in the cassette case passes, whereby the window member
64
frequently peels off from the fixing surface
65
a
of the periphery of the window opening
65
, and particularly from the vicinity of the corner portion C onto which the concentrated load acts. This is a problem.
On the other hand, in the above conventional magnetic tape cassette
50
, the window member
64
is formed by resin injection molding. At this time, as shown in
FIG. 9
, a fine line like a hair line that is formed at a portion where more than two streams of the molten resin join, that is, a weld line W is produced in the window member
64
.
The conventional window member
64
has adopted such a constitution that a gate position is set to a position shown by reference numeral
69
, and that a valve gate is divided into three before a portion leading to a gate outlet and their divided valve gates are joined before the gate outlet. Accordingly, the weld line produced in the junction before the gate outlet flows intactly together with the melted resin, and as shown in
FIG. 6
, the weld line W is frequently produced between the welded ribs
66
,
66
that are comparatively near the gate position
69
.
In case that the window member
64
in this state is going to be welded onto the fixing surface
65
a
formed on the periphery of the window opening
65
of the upper half
51
by the ultrasonic vibration, there is an occasion that a crack starts from the weld line W. This is a problem.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the aforementioned problem.
A first object of the invention is to reliably weld the window member to the upper half.
A second object of the invention is to provide a magnetic tape cassette that prevents the window member from peeling off without damaging the appearance and with the simple structure.
A third object of the invention is to provide a resin product having no fear of the crack even in case that the resin product is firmly attached to some product by welding.
The object of the invention can be achieved by a magnetic tape cassette comprising a cassette case having upper and lower halves, a tape reel which winds th
Heinz A. J.
Sughrue & Mion, PLLC
LandOfFree
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