Magnetic tape cassette

Details Magnetic tape cassette Magnetic tape cassette

2000-06-09

2001-09-11

Nguyen, John Q. (Department: 3653)

Winding, tensioning, or guiding

Unwinding and rewinding a machine convertible information...

Cartridge system

C360S132000

Reexamination Certificate

active

06286776

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a magnetic tape cassette which is utilized in a magnetic recording and replaying apparatus, such as a video tape recorder, and other various kinds of information processing apparatuses.
In addition, the present invention specifically relates to a type of magnetic tape cassette wherein a closing lid unit which covers an opening at a front part of the cassette main body so as to be opened and closed freely consists of three lids.
Further, the present invention also relates to a magnetic tape cassette which is preferably utilized in such as a video tape cassette, wherein a lid lock spring that applies force to a lid lock which locks a lid that covers and uncovers an opening at a front end of a cassette case and an attaching structure thereof are improved.
With further increase in magnetic recording density in recent years, magnetic tape cassettes and video tape recorders (hereinafter referred to as VTRs) have become more compact. As the result, VTRs are used outdoors more frequently in such a case as videotaping scenery and figures. Therefore, the magnetic tape cassettes also specially consider outdoor use and a closing lid unit which consists of two or three lids for covering the front and rear sides of the tape has been utilized as a dust-preventive countermeasure.
FIGS. 1 through 3
show a conventional magnetic tape cassette wherein three lids constitute a closing lid unit for covering an opening at a front part of a cassette main body so as to be opened and closed freely.
This magnetic tape cassette
1
comprises a cassette main body
4
which comprises an opening
2
at a front part for insertion of a tape picking element on the side of such an apparatus as a VTR, a magnetic tape
5
which is suspended over the opening by a tape guide provided at the front part of such cassette
4
and a closing lid unit
7
which is attached to a front side of the cassette main body
4
so that the magnetic tape
5
suspended over the opening
2
will be covered for such an occasion as portable use.
The cassette main body
4
consists of an upper cassette half
4
a
and a lower cassette half
4
b
. The closing lid unit
7
consists of three lids, an outer lid (front lid)
9
, a top lid (upper lid)
10
and an inner lid (rear lid)
11
.
The outer lid
9
comprises an outer lid plate
9
a
which covers a front side of the magnetic tape
5
suspended over the opening
2
and side plate portions
9
b
which extend from both sides of this outer lid plate
9
a
. Supporting axle-pins
9
c
are provided so as to protrude from the inner wall surfaces of the side plate portions
9
b
, and such supporting axle-pins
9
c
are fitted in and supported by pin holding holes on both lateral side portions of the upper cassette half
4
a
at positions close to the front thereof so as to revolve freely. Therefore, the outer lid
9
revolves freely with the supporting axle-pins
9
c
as revolving centers.
The top lid
10
comprises a top lid plate
10
a
which covers an area above the magnetic tape
5
which is suspended over the opening
2
, outer lid linking portions
10
a
that link both ends of this top lid plate
10
a
at the front edge side thereof to a top edge of the outer lid plate
9
a
so as to revolve freely and top lid slide pins
10
d
that protrude from arm portions
10
c
which extend from the rear end edge of the top lid plate
10
a
and that engage with top lid guide grooves
13
which are formed on both the lateral side portions of the upper cassette half
4
a
so as to slide freely.
As shown in
FIG. 3
, when the outer lid
9
is opened, this top lid
10
moves to the rear end side of the cassette main body
4
to be approximately parallel to the upper surface of the cassette main body
4
while the top lid slide pins
10
d
move along the top lid guide grooves
13
according to a revolutionary transfer movement around the supporting axle-pins
9
c
of the outer lid linking portions
10
b
. The outer lid linking portions
10
b
are pins which fit in engagement holes
9
d
(not shown) that are provided in both top edge end portions of the outer lid plate
9
a.
The inner lid
11
, which comprises an inner lid plate
11
a
that covers a rear side of the magnetic tape
5
which is suspended over the opening
2
, top lid linking portions
11
b
that link a top edge of this inner lid plate
11
a
to the top lid plate
10
a
so as to revolve freely and inner lid slide pins
11
c
that protrude from both ends of a bottom edge of the inner lid plate
11
a
and that engage with inner lid guide grooves
15
which are formed on inner lateral side portions of the cassette main body
4
so as to slide freely. In this embodiment, as shown in
FIG. 2
, the top lid linking portions
11
b
are pins which fit in supporting holes
10
f
(not shown) that are provided in supporting pieces
10
e
which protrude from the top lid plate
10
a.
To describe the inner lid
11
, when the outer lid
9
is opened, while the top lid linking portions
11
b
follow the movement of the top lid
10
, the inner lid slide pins
11
c
move along the inner lid guide grooves
15
according to a transfer movement of such top lid linking portions
11
b
. As shown in
FIG. 3
, the inner lid
11
follows the opening action of the top lid
10
and retreats to the area above the opening
2
.
When the magnetic tape cassette
1
, such as described above, is mounted on a VTR apparatus, the side plate portions
9
b
of the outer lid
9
are pushed upward by a lid opening pin (not shown) which is provided on the apparatus side and, corresponding to the opening action of the outer lid
9
, the top lid
10
and the inner lid
11
are opened. When the magnetic tape cassette
1
is removed from the VTR apparatus, the lids are closed in a manner reverse to that of mounting.
To assemble such magnetic tape cassette
1
as having a three-plate closing lid unit
7
, the outer lid
9
, the top lid
10
and the inner lid
11
are assembled temporarily in advance and then, while the top lid slide pins
10
d
of the top lid
10
are being fitted in the top lid guide grooves
13
which has been provided in the upper cassette half
4
a
, the three lids
9
,
10
and
11
are attached to the upper cassette half
4
a
to be followed by attaching of the upper cassette half
4
a
and the lower cassette-half
4
b.
In the assembling procedures as above, however, the lower cassette half
4
b
which houses a large number of components and the upper cassette half are attached last, such operations as positioning of the large number of components housed in the lower cassette half
4
b
must be carried out at the same time as the operation to fit the inner lid slide pins
11
c
into the inner lid guide grooves
15
of the lower cassette half
4
b
; the assembling operation is thus an elaborate process and has obstructed increase in the productivity. This is a first problem in the prior art.
In the above-described magnetic tape cassette
10
, a motion locus of the top lid
10
is defined by the top lid guide grooves
13
and, between the sliding surfaces
13
a
and
13
b
of such top lid guide grooves
13
and the top lid slide pins
10
d
of the top lid
10
, frictional force that work as a sliding resistance is generated.
Some dimensions and configurations of these sliding surfaces
13
a
and
13
b
and the top lid slide pins
10
d
may hinder the top lid slide pins
10
d
from sliding smoothly when the outer lid
9
is opened and closed, resulting with difficulty in opening of the closing lid unit
7
. For example, a force of pressure angle &thgr;, which is a force working in a specific direction, acts from the outer lid linking part
10
b
via such top lid slide pin
10
d
against the sliding surface
13
a
that the top lid sliding pin
10
d
is in sliding contact with and, if such pressure angle &thgr; is larger than a certain range of values, the smooth sliding of the top lid slide pin
10
d
is hindered to result with difficulty in opening of the closing lid unit
7
. This is a second problem in the

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