Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
2002-02-13
2003-12-02
Nguyen, John Q. (Department: 3654)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
C360S132000
Reexamination Certificate
active
06655625
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a magnetic tape cartridge having a lid that can open and closes an opening portion for drawing out a magnetic tape.
The present application is based on Japanese Patent Applications Nos. Hei. 10-36170, 10-79455 and 10-350136, the contents of which are incorporated herein by reference.
BACKGROUND ART
A magnetic tape cartridge has been used as recording medium for computers etc. As an example of such the magnetic tape cartridge, there has been known a magnetic tape cartridge which comprises: a reel; a magnetic tape wound around the reel; and a cartridge case including an upper cartridge and a lower cartridge, wherein the reel is accommodated in the cartridge case so as to be able to rotate. A lid is pivotably attached to the cartridge case so as to be able to open and close an opening portion formed in the cartridge case. When the magnetic tape cartridge is used, the opening portion is opened by the lid so that the magnetic tape may be drawn out of an opening portion.
When the magnetic tape cartridge is not used, the opening portion is closed by the lid. At this stage, a leader tape attached to a tape end is locked at an end surface of the cartridge case in such a state that the magnetic tape is fully wound up onto the reel while the reel is locked by such a lock component as a reel lock so as to prevent unexpected rotations of the reel. Incidentally, the leader tape is an engagement mechanism for such an apparatus as a computer to introduce the magnetic tape into a tape path.
The lid and the locking structure thereof will be described. In the cartridge case described above, the magnetic tape is wound around the reel rotatably mounted, and the leader tape is positioned at the opening portion when the lid closes the opening portion. The reel is comprised of a set of upper and lower reels, in which a gear portion is formed on the outer circumferential portion of the upper reel.
FIG. 1
shows a basic attachment structure of a lid
60
. As shown in
FIG. 1
, the lid
60
is mounted on an upper cartridge
2
a
through a supporting shaft
14
. The lid
60
is urged by a lid spring
65
in a closing direction as indicated by an arrow A. The lid spring
65
is attached to the supporting shaft
14
through a coil portion
65
c
thereof, and one leg portion
65
b
is supported by the frame
2
d
of the upper cartridge
2
a
while the other leg portion
65
a
is supported by a recessed portion
67
formed in the lid
60
.
The lid
60
has a hole
61
into which a lid lock member
70
for locking the opening or closing actions of the lid
60
is inserted. The lid lock member
70
can vertically slide in the hole
61
in a cartridge thickness direction. The lid lock member
70
is located adjacent to the supporting shaft
14
when the lid
60
is mounted on the upper cartridge
2
a
. As shown in
FIG. 1
, the lid lock member
70
is urged by an upward force of a lid lock spring
16
in a direction indicated by an arrow U, to lock the lid
60
so as not to open by the upper end thereof being engaged with a recessed portion formed in the lower cartridge (not shown) when the magnetic tape cartridge is not used.
To ensure high accuracy and flame resistance, the lid
60
and the cartridge case are respectively made of a composite material of polycarbonate and glass fiber. The lid lock member
70
is made of a material excellent in sliding effect, such as POM, in order to reduce friction. The supporting shaft
14
is molded as a part of the upper cartridge
2
a
for the reasons of accuracy and costs. A shaft hole
63
through which the supporting shaft
14
is passed is molded as a part of the lid
60
for the reasons of accuracy and costs.
FIG. 2
shows positional and kinetic relationship between the lid
60
and the lid spring
65
in a static state where the lid is opened while a certain torque is being loaded on the lid spring
65
. As for the kinetic relationship while the lid
60
is opened, a torque Ts
1
of the lid spring
65
is applied to the spring bearing portion
68
of the lid
60
to generate a spring force F
6
. An opening force F
5
is applied to the lid
60
through a release lever (not shown) for opening the lid
60
. A load F
7
is applied on the supporting shaft
14
. The load F
7
is a difference between the forces F
6
and F
5
. In this magnetic tape cartridge, the Ts
1
is set as 140 gfcm in view of parameters of a lid spring which is generally utilized in this magnetic tape cartridge. A radius r of the supporting shaft
14
is 0.2 cm. A distance d
1
from the center of the supporting shaft
14
to a point of action of the force F
6
is 0.3 cm. A distance d
2
from the center of the supporting shaft
14
to a point of action of the force F
5
is 1.1 cm.
A relationship among T (torque), F (force), and d (distance) is defined as follows:
T
(torque)=
F
(force)×
d
(distance)
In view of the above, the specific values of F
6
and F
5
are defined as follows:
F
6
=
Ts
1
/
d
1
=467
gf
F
5
=
Ts
1
/
d
2
=127
gf
Further, the specific value of F
7
is defined based on balance of the forces as follows:
F
7
=
F
6
−
F
5
=340
gf
Accordingly, if a static friction coefficient &mgr; of the resin is set as 0.52, a friction torque Tf
1
of the supporting shaft
14
is defined as follows:
Tf
1
=
F
7
×&mgr;×
r
=35
gfcm
FIG. 3
shows positional and kinetic relationship between the lid
60
and the lid spring
65
in a static state where the lid
60
is closed. As for the kinetic relationship while the lid
60
is closed, a torque Ts
2
of the lid spring
65
is applied to the spring bearing portion
68
of the lid
60
to generate a spring force F
2
. A counter force Fe is applied from the leader tape
21
to the lid
60
. A load F
3
applied to the supporting shaft
14
is a sum of F
2
and Fl. Incidentally, in this magnetic tape cartridge, the Ts
2
is 60 gfcm and the force Fl is 8 gf while the distance d
3
from the center of the supporting shaft
14
to a point of action of the force Fl is 4.5 cm.
In view of the above, the specific value of F
2
is defined as follows:
F
2
=
Ts
2
/
d
1
=200
gf
Therefore, the specific value of F
3
is defined based on balance of the forces as follows:
F
3
=
F
2
+
Fl
=208
gf
Accordingly, a friction torque Tf
2
of the supporting shaft
14
is defined as follows:
Tf
2
=
F
3
×&mgr;×
r
=22
gfcm
As a result, a spare torque Tt of the lid spring
65
in the close state of the lid
60
is defined as follows:
Tt=Ts
2
−(
Tf
2
+
T
1
)=2
gfcm
(wherein T
1
=8×4.5=36 gfcm)
That is, the closing action of the lid
60
is maintained by the above torque Tt.
As described above, the material, represented by such as polycarbonate which can ensure the high accuracy and the flame resistance, has a large friction coefficient as a synthetic resin (friction coefficient &mgr;=0.4 to 0.6). Therefore, the lid
60
may be stopped in the middle of the pivotal action due to the rotational resistance between the supporting shaft
14
and the shaft hole
63
. Further, there is a possibility in that the load is increased on the drive of an apparatus, such as a computer, when the lid
60
is pivoted.
Additionally, when the lid
60
is opened, since the lid lock member
70
moves while the lid lock member
70
is being pushed toward the upper cartridge
2
a
by the door releasing lever of the drive, thrust friction between the lid
60
and the upper cartridge
2
a
increases, and therefore the opening operation may require more force and friction powder may be generated. On the other hand, when the lid
60
is closed, since the lid lock member
70
pushes the lower cartridge, the friction occurs between the lid lock member
70
and the lower cartridge, and further, the thrust friction is caused between the lid
60
and the upper cartridge
2
a
by a counter force applied to the lid
60
by the lid lock member
70
. Since the lid
60
an
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