Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
1992-10-26
2002-07-16
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Record medium
In container
Reexamination Certificate
active
06421203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a magnetic tape cassette for use with a digital audio tape recorder (DAT) or the like and, more particularly, is directed to a magnetic tape cassette in which a slider can be reliably engaged with a lower cassette part at a predetermined position.
2. Description of the Prior Art
Conventional tape recorders such as a digital audio tape recorder (DAT) or the like employ a magnetic tape cassette which is generally depicted by reference numeral
11
in
FIGS. 1
to
3
, for example.
As illustrated, in the case of the magnetic tape cassette for the DAT, a magnetic tape T is protected not only by upper and lower cassette parts
2
,
3
but also by a lid
7
, a slider
8
or the like in order to prevent a drop-out from occurring in a reproduced signal when the surface of the magnetic tape T is smudged by fingermarks, oily components, dust or the like.
A pair of reel hubs
5
a,
5
b
around which the magnetic tape T is wound is accommodated within a cassette housing
4
that is composed of the upper cassette shell or part
2
and the lower cassette shell or part
3
which are fastened together by some suitable means such as screws or the like. A transparent window
2
a
is formed on the upper cassette part
2
so that the user can visually confirm the remaining amount of the magnetic tape T wrapped around the reel hubs
5
a
and
5
b
. Also, in order to prevent the magnetic tape T from being exposed through a mouth portion
6
of the cassette housing
4
when the magnetic tape cassette
11
is not in use or when the magnetic tape cassette
11
is preserved, a lid
7
is pivotally attached to the front portion of the cassette housing
4
such that the lid
7
becomes freely rotatable in the upper direction. The lid
7
is constantly spring-biased by a spring (not shown) in the direction in which the lid closes the mouth portion
6
.
The slider
8
is provided on the lower cassette part
3
so that it slides along the lower cassette part
3
back and forth (in the directions shown by arrows a and b in
FIGS. 2A
,
2
B) to thereby open and close the mouth portion
6
. The slider
8
has bored therethrough a pair of reel shaft insertion apertures
8
b
,
8
b
that communicate with a pair of reel shaft insertion apertures
3
b
,
3
b
bored through the lower cassette part
3
at the opening position of the mouth portion
6
. The slider
8
is constantly spring-biased by a slider spring S in the forward direction (in the arrow a direction (see
FIG. 2A
) in which the slider
8
closes the mouth portion
6
) relative to the lower cassette part
3
.
When the magnetic tape cassette
11
thus arranged is not in use, as shown in
FIG. 2A
, the lid
7
closes the front portion of the mouth portion
6
and the slider
8
closes the lower portion of the mouth portion
6
, whereby the magnetic tape T extended within the mouth portion
6
is isolated from the outside. The reel shaft insertion apertures
3
b
of the lower cassette part
3
and the reel shaft insertion apertures
8
b
of the slider
8
are not coincident with one another and the slider
8
closes the reel shaft insertion apertures
3
b
of the lower cassette part
3
, thereby preventing the inside of the cassette housing
4
from being smudged by dust or the like.
When the magnetic tape cassette
11
is loaded onto a recording and reproducing apparatus such as the DAT or the like, as shown in
FIG. 2B
, the slider
8
is slid rearward of the cassette housing
4
(in the arrow b direction) and then held. Also, the lid
7
is rotated upwardly to open the front portion and the lower surface of the mouth portion
6
.
Under this condition, a tape loading guide member (not shown) on the recording and reproducing apparatus side can be inserted into the mouth portion
6
of the cassette housing
4
. Also, the reel shaft insertion apertures
8
b
,
8
b
of the slider
8
become coincident with the reel shaft insertion apertures
3
b
,
3
b
of the lower cassette half
3
, whereby reel shafts (not shown) of the recording and reproducing apparatus can be inserted into the reel shaft insertion apertures
3
b
,
8
b.
When the magnetic tape cassette
11
is not in use, the slider
8
is moved forwardly and held at the position at which the slider closes the mouth portion
6
. When the magnetic tape cassette
11
is loaded onto the recording and reproducing apparatus, the slider
8
is moved backwardly and then held at the position at which the slider opens the mouth portion
6
. In order to hold the slider
8
at the respective predetermined positions, two pairs of engagement apertures
8
c
,
8
c
and
8
d
,
8
d
are bored through the slider
8
at two positions in the arrow b direction in
FIG. 2B and a
pair of slider lock portions
3
c
,
3
c
of pin-configuration that can be engaged with the engagement apertures
8
c
,
8
c
and
8
d
,
8
d
are formed on the lower cassette part
3
.
As shown in
FIGS. 1 and 3
, the slider lock portions
3
c
,
3
c
are formed by cutting one portion of the lower cassette part
3
. These slider lock portions
3
c
,
3
c
have a spring-biasing property so that the respective engagement protrusions
3
d
,
3
d
formed on the tops thereof are constantly spring-biased so as to return to the direction in which the engagement protrusions
3
d
,
3
d
are engaged with the engagement apertures
8
c
or
8
d
of the slider
8
. In order to prevent the returning force of the slider lock portions
3
c
,
3
c
from being reduced when the lower cassette part
3
is deformed by the deterioration of the material forming the lower cassette part
3
, it is proposed that compression coil springs (hereinafter referred to as slider lock springs)
9
,
9
be respectively interposed between the engagement protrusions
3
d
,
3
d
of the slider lock portions
3
c
,
3
c
and the upper cassette part
2
.
FIG. 3
of the accompanying drawings shows an example of the slider lock spring
9
that the assignee of the present application has previously proposed (see Japanese Patent Application No. 3-48741). As shown in
FIG. 3
, the slider lock spring
9
comprises a spring body portion
9
a
formed of a coil spring whose inner diameter is progressively increased upwardly and an elongated portion
9
b
that is linearly elongated from the upper end edge of the spring body portion
9
a
. The coil spring is doubly wound around only the upper and lower end portions tightly.
In the slider lock springs
9
,
9
thus arranged, the spring body portions
9
a
,
9
a
are wound around a pair of pins
2
b
,
2
b
protruded from the inner side surface of the upper cassette part
2
in response to the inner surface sides of the tops of the engagement protrusions
3
d
,
3
d
of the slider lock portions
3
c
,
3
c
. The elongated portion
9
b
is welded (fixed by a caulking process) to a recess
2
d
of a fixed portion
2
c
of the upper cassette part
2
. Therefore, the slider lock springs
9
,
9
can be prevented from disenging from the upper cassette part
2
and come in contact with the inner end faces of the engagement protrusions
3
d
,
3
d
of the slider lock portions
3
c
,
3
c
to downwardly press the engagement protrusions
3
d
,
3
d
, thereby reinforcing the spring-biasing force of the slider lock portions
3
c
,
3
c.
The above conventional magnetic tape cassette
11
, however, suffers from the following disadvantages:
That is, if the spring-biasing force of the slider lock spring
9
is increased, although the returning force of the slider lock portion
3
c
is reinforced more effectively, a force (opening force) that is required to open the slider
8
must be increased because the top end faces of the respective engagement protrusions
3
d
are brought in parallel contact with the respective engagement apertures
8
c
when the engagement protrusions
3
d
of the slider lock portions
3
c
are disengaged from the engagement apertures
8
c
of the slider
8
.
There is then the antinomy that, while the spring-biasing force of the slider lock
Davis David
Maioli Jay H.
Sony Corporation
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