Head carriage

Details Head carriage Head carriage

2000-06-05

2004-02-17

Watko, Julie Anne (Department: 2652)

Dynamic magnetic information storage or retrieval

Head mounting

Disk record

C360S266200

Reexamination Certificate

active

06693772

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a head carriage device of a floppy disc drive used as an external memory device and the like of a computer.
2. Description of the Related Art
FIG.
9
and
FIG. 10
are a plan view and a side view, respectively, of a head carriage device
1
.
FIG. 11
is a front view, in a direction E, of the head carriage device
1
shown in FIG.
9
.
As shown in
FIGS. 9 and 10
, the head carriage device
1
includes a carriage
2
, which is held movably in a radial direction of a floppy disc
9
(in a direction R in the drawings) and which is provided with a magnetic head
5
. The head carriage device
1
also includes a head arm
3
having a magnetic head
6
opposing the magnetic head
5
, a flat spring
4
extending from an end
3
b
of the head arm
3
, and a fixing member
11
connecting the flat spring
4
to the carriage
2
. The fixing member
11
overlaps a free end of the flat spring
4
. The head carriage device
1
further includes a torsion spring
7
resiliently urging the magnetic head
6
toward the magnetic head
5
at an anchoring point
3
c
provided at the central part in the width direction (in a direction shown by arrows W in
FIG. 9
) of the head arm
3
, and a finger
3
a
supported by a lifting mechanism
8
and protruding toward the outside from one of the sides along the direction R of the head arm
3
, for pivoting the head arm
3
in direction increasing the spacing between the magnetic head
6
and the magnetic head
5
(direction A in FIG.
10
).
The head carriage device
1
operates as follows. When a cartridge
10
holding a floppy disc
9
is inserted in a floppy disc drive (not shown), as shown in
FIG. 11
, the lifting mechanism
8
is applied to the finger
3
a
. The magnetic head
6
moves in the direction A (unloading direction) while being supported through the finger
3
a
, as shown in FIG.
10
. The lifting mechanism
8
forces the distance between the magnetic head
6
and the magnetic head
5
to increase, against the resilient force of the torsion spring
7
.
When the cartridge
10
is completely inserted in the floppy disc drive, the lifting mechanism
8
releases the unloaded state of the head arm
3
. The head arm
3
then moves in a direction B (loading direction), as shown in
FIG. 10
, in which the magnetic head
6
approaches the magnetic head
5
, and the magnetic heads
5
and
6
clamp the floppy disc
9
with a predetermined pressing force. The pressing force is determined by the torsion spring
7
. The floppy disc
6
is subsequently driven by a spindle motor (not shown) and reading/writing of information is performed by the magnetic heads
5
and
6
.
However, in the head carriage device
1
, in which the head arm
3
turns while being supported at one side of the head arm
3
, it is possible for the magnetic head
6
to interfere with the cartridge
10
at an end
6
a
of the magnetic head
6
when inserting the cartridge
10
in the floppy disc drive. This interference occurs due to the structure of the head carriage device
1
. Because the head arm
3
is fixed to the carriage
2
through the fixing member
11
at the free end of the flat spring
4
extending from the end
3
b
of the head arm
3
, when the head arm
3
turns along the direction A shown in
FIG. 10
, the head arm
3
is inclined from a horizontal line H shown in FIG.
11
. Thus, the distance between the magnetic head
6
mounted on the head arm
3
and the magnetic head
5
is larger at an end
6
b
of the magnetic head
6
at the side of the finger
3
a
than the distance at the opposing end
6
a
of the magnetic head
6
. A torque D, shown in
FIG. 11
, causes the inclination of the head arm
3
. The torque D is produced because an anchoring point C of the finger
3
a
, to which the lifting mechanism
8
is applied, is disposed at a distance from the anchoring point
3
c
of the head arm
3
to which a pressing force F of the torsion spring
7
is applied.
Another head carriage device
20
, shown in
FIGS. 12 and 13
, is disclosed in Japanese Unexamined Patent Application Publication No. 2-11541. This head carriage device
20
prevents the inclination described above. FIG.
12
and
FIG. 13
are a plan view and a side view of the head carriage device
20
, respectively.
The head carriage device
20
shown in
FIGS. 12 and 13
includes a carriage
21
, a head arm
22
, a magnetic head
23
mounted on the head arm
22
at an end thereof, and a magnetic head
31
mounted on the carriage
21
. A flat spring
24
, a fixing member
25
, and a torsion spring
27
are disposed opposing the magnetic head
23
. Components that have the same function as that of the components of the head carriage device
1
shown in
FIGS. 9
,
10
, and
11
are referred to with the same reference numerals in
FIGS. 12 and 13
.
In the head carriage device
20
, a first protrusion
22
b
protrudes over the upper face of the flat spring
24
from an end of one of the lateral sides of the head arm
22
along a direction R of the head arm
22
, and a second protrusion
25
a
protrudes over the upper face of the flat spring
24
from the fixing member
25
at the other lateral side, provided with a finger
22
a
, of the head arm
22
. The first and second protrusions
22
b
and
25
a
oppose each other in the width direction of the head arm
22
.
With this arrangement, as shown in
FIG. 12
, when the head arm
22
moves in a direction A shown in
FIG. 13
while being supported by the lifting mechanism
26
at the finger
22
a
, the flat spring
24
twists along a line
28
extending between joining parts M and N in a flexible part of the flat spring
24
. The line
28
forms an angle &thgr; with a line
30
along the width of the head arm
22
, because the joining part M disposed in the vicinity of the first protrusion
22
b
formed on the head arm
22
is closer to the fixing member
25
than the joining part N disposed in the vicinity of the second protrusion
25
a
formed on the fixing member
25
.
When the torsion spring
27
shown in
FIG. 12
is eliminated, the head arm
22
is inclined from the horizontal line H by an angle &agr;, as shown in
FIG. 14A
, in a manner such that a lateral side
22
-
2
of the head arm
22
is disposed higher than a lateral side
22
-
1
thereof which opposes the lateral side
22
-
2
and which is provided with the finger
22
a.
The head arm
22
provided with the torsion spring
27
at a central part P of the head arm
22
, as shown in
FIG. 14B
, which is the position of the anchoring point
22
c
, is kept horizontal by the torque D shown in FIG.
11
. The torque D is produced by the pressing force of the torsion spring
27
and offsets the inclination in which the lateral side
22
-
2
is higher than the lateral side
22
-
1
by angle &agr;.
However, with this arrangement, a problem exists in that the head arm
22
cannot be maintained in a stable horizontal position perpetually. The pressing force of the torsion spring
27
and the lifting force of the flat spring
24
lifting the lateral side
22
-
2
of the head arm
22
to form angle &agr; are not always balanced due to variations in the angle &agr; and the pressing force F (shown in FIG.
11
). These variations are caused by variations in the thickness of the flat spring
24
, which is within the manufacturing tolerances, and variations in pressing force of the torsion spring
27
.
As shown in
FIG. 14A
, the flexible part of the flat spring
24
comes into contact with the first protrusion
22
b
having a width L
5
and the second protrusion
25
a
having a width L
6
at the joining parts M and N, respectively. Another problem of the head carriage device
20
is that the width L
5
and the width L
6
are small and large stresses are concentrated thereto when the head arm
22
turns. This reduces the durability of the flat spring
24
. The flat spring
24
is plastically deformed and eventually breaks at the joining parts M and N due to the repeated pivoting motion of the head arm
22
. This reduces the durabili

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