Magnetic tape cassette

Details Magnetic tape cassette Magnetic tape cassette

2001-09-27

2003-08-19

Rivera, William A. (Department: 3654)

Winding, tensioning, or guiding

Unwinding and rewinding a machine convertible information...

Cartridge system

C242S345000, C242S346000, C242S347000, C360S132000

Reexamination Certificate

active

06607155

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic tape cassette for used in an apparatus having a light source and a pair of light sensors to detect a tape end of the magnetic tape cassette in which a cassette housing is combined with transparent or semi-transparent upper half and lower half.
2. Description of the Related Art
The assignee of the present invention disclosed a magnetic tape cassette (hereinafter referred to as “tape cassette”) for preventing an erroneous detection of a tape end irrelevant to material of a cassette housing and for being capable of mass production, and for having a color of higher transparency which color the manufacturer intends for such the tape cassette. The tape cassette in accordance with the related art is described as follows with reference to
FIGS. 9 through 12
.
FIG. 9
is a plan view of a lower half of a tape cassette for having a light-shielding member for preventing an erroneous detection of the tape end caused by receiving too much light at a light sensor incorporated in an apparatus such as VCR.
In
FIG. 9
, a tape cassette
1
is composed of a lower half
1
a
and an upper half
1
b
(not shown), and includes a room
20
for containing a take-up (TU) reel
23
on which a magnetic tape is winded up, another room
21
for containing a supply (SP) reel
24
on which a magnetic tape is supplied to the TU reel
23
, a light hole
3
for inserting a light source incorporated in an apparatus not shown, a pair of light sensors
5
a
and
5
b
incorporated in the apparatus which receive light emitted from the light source through a pair of light paths
4
a
and
4
b
respectively, a light exits
701
and
702
for passing the light emitted from the light source, ribs
801
and
802
formed together with the lower half
1
a,
a light shielding member
2
a
and
2
b
for limiting an irregular reflection caused by the light emitted from the light source from coming into the light sources
5
a
and
5
b.
The portion A and B in
FIG. 9
show the position where the light shielding members
2
a
and
2
b
are placed in the tape cassette
1
.
In
FIG. 9
, the light emitted from the light source inserted in the light hole
3
reaches the light sensors
5
a
and
5
b
through the light paths
4
a
and
4
b
respectively. On the other hand, the both ends of the magnetic tape (not shown) are connected to the SP reel
24
and TU reel
23
respectively through an intermediary leader tape (not shown). The magnetic tape forms a tape travel path (not shown) to connect to the SP reel
24
and the TU reel
23
, wherein the tape travel path crosses the light paths
4
a
and
4
b.
Generally, in the tape cassette made by low light transmittance material (such as black colored material), the light emitted from the light source reaches to the light sensor
5
a
and
5
b
incorporated in the VCR through the light paths
4
a
and
4
b
respectively. As the leader tape is not having a magnetic powder, the light emitted from the light source can reach to the light sensors
5
a
and
5
b
through the leader tape. To the contrary, the magnetic tape blocks the light emitted from the light source. As a result, the tape end can be detected by the difference of amount of light received at the light sensors
5
a
and
5
b
when the leader tape passes the light emitted from the light source to the light sensors
5
a
and
5
b.
FIG. 10
is a cross-sectional view of the tape cassette
1
having an upper half
1
b
and a lower half
1
a
with a thickness T, made of a transparent or a semi-transparent material without having the light shielding member
2
a
between the light hole
3
and the light sensor
5
a,
wherein the light source LS is inserted in the light hole
3
.
In
FIG. 10
, the light emitted from the light source LS will be reflected irregularly inside the tape cassette
1
as an irregular light
6
. As the light shielding member
2
a
is not placed between the room
20
for the TU reel
23
and the light sensor
5
a,
the irregular light
6
will also reach to the light sensor
5
a.
In case that the tape cassette
1
consists of an upper half
1
b
and a lower half
1
a
made of a transparent or semi-transparent material, the light sensors
5
a
and
5
b
may receive the irregular light
6
even when the magnetic tape crosses the light paths
4
a
and
4
b
that the apparatus may erroneously determine that the tape end has been detected.
Accordingly, the assignee of the present invention discloses a tape cassette shown in
FIG. 11
having a light shielding member
2
a
placed at the rib
801
of the tape cassette
1
.
FIG. 11
is a cross-sectional view of the tape cassette
1
shown in
FIG. 10
for having the light shielding member
2
a
between the light hole
3
and the light sensor
5
a.
As shown in
FIG. 11
, the irregular light
6
is blocked by the light shielding member
2
a
and will not reach to the light sensor
5
a.
FIGS. 10 and 11
show the relation between the room
20
for the TU reel
23
and the light sensor
5
a,
but of course, the relation of the room
20
and the light sensor
5
a
can be applied to the relation of the other room
21
for the SP reel
24
and the light sensor
5
b
as well.
FIG. 12
is a perspective view of the portion A shown in
FIG. 9
for explaining the light shielding member
2
a.
In
FIG. 12
, the light shielding member
2
a
has a light window
11
to pass only the light emitted from the light source through the light path
4
a,
and blocks the irregular light
6
. The light shielding member
2
a
is fixed at the rib
801
by an adhesive.
As described above, the irregular light
6
reflected diffusely inside the upper half
1
b
and the lower half
1
a
can be blocked by placing the light shielding member
2
a
and
2
b
on the light paths
4
a
and
4
b
at the ribs
801
and
802
of the tape cassette an a be prevented from reaching to the light sensors
5
a
and
5
b.
However, as the upper half
1
b
and the lower half
1
a
are being made of a transparent or semi-transparent material, the light emitted from the light source LS may pass through the material itself as an irregular light
6
b
and radiated from the edge of the upper and lower half (the edge
100
), and eventually reaches the light sensor
5
a.
This irregular light
6
b
is difficult to be blocked by only the light shielding member
2
a.
Such the irregular light
6
b
radiated from the edge
100
may reach to the light sensor
5
a
and the VCR may erroneously detect the tape end. In order to prevent the VCR from this malfunction to erroneously detecting the tape end, the irregular light
6
b
should be blocked. This may happen to the portion B in
FIG. 9
that such the irregular light
6
b
may reach to the light sensor
5
b,
which also should be blocked.
SUMMARY OF THE INVENTION
Accordingly, in consideration of the above-mentioned problems of the related art, an object of the present invention is to provide a magnetic tape cassette used in an apparatus having a light source (LS) and a light sensor (
5
a,
5
b
) for detecting a tape end of a magnetic tape being loaded therein, the magnetic tape cassette including, a cassette housing being formed by combining an upper half (
1
b
) and a lower half (
1
a
) made of transparent or semi-transparent member, wherein the cassette housing is equipped with a reel being connected to the magnetic tape through an intermediary leader tape having higher light transmittance for winding up the magnetic tape, a light exit (
7
A,
7
A
1
,
7
A
2
) being opposed to the light sensor (
5
a,
5
b
) when the magnetic tape cassette is loaded to a predetermined position in the apparatus, for passing light from the light source (LS) to the light sensor (
5
a,
5
b
) through the light exit (
7
A,
7
A
1
,
7
A
2
), wherein a light path (
4
a,
4
b
) of the light emitted from the light source (LS) crosses a travel path of the magnetic tape, and a rib (
8
) being formed in the upper half (
1
b
) and the lower half (
1
a
) wherein a plurality of triangular shaped prism (
8
a
)

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