Magnetic head device

Details Magnetic head device Magnetic head device

1998-10-06

2001-04-03

Ometz, David L. (Department: 2652)

Dynamic magnetic information storage or retrieval

Head mounting

Disk record

C360S244200

Reexamination Certificate

active

06212044

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a magnetic head device for applying a magnetic field to an information recording medium in a recording device for optomagnetic disks such as mini disks (referred to below as “MD”s) or optomagnetic data filing systems.
BACKGROUND OF THE INVENTION
In conventional optomagnetic recording/reproducing devices, an optical head device opposes one side of an optomagnetic disk, which serves as an information recording medium that is rotated by a driving mechanism. The optical head device emits a light beam for irradiating an optomagnetic recording layer of the optomagnetic disk. A magnetic head device opposes the other side of the optomagnetic disk and applies an external magnetic field to the optomagnetic recording layer.
The optomagnetic recording/reproducing device applies a magnetic field to the optomagnetic recording layer of the rotating optomagnetic disk by letting the magnetic head device modulate the direction of the magnetic field in accordance with the information signal to be recorded, while the optical head emits a light beam that is focused on the optomagnetic recording layer.
This light beam heats a portion of the optomagnetic recording layer to a temperature above the curie temperature, so that this portion loses its coercive force. After this portion has been magnetized in the direction of the magnetic field applied by the magnetic head device, the optomagnetic disk is moved by rotation relative to the light beam, so that the temperature of this portion drops below the curie temperature and the magnetization direction is fixed. Thus, an information signal is recorded in the optomagnetic recording layer.
Since there is a possibility that the optomagnetic disk sways during the rotation, recent optomagnetic recording/reproducing devices comprise sliding magnetic head devices. A sliding magnetic head device records the information signal while sliding on the MD. Such a conventional magnetic head device is disclosed, for example, in Publication of Unexamined Japanese Patent Application No. Hei 8-147914.
The following is a more detailed explanation of a conventional magnetic head device, with reference to
FIGS. 9-14
.
FIG. 9
is a perspective view of an example of a conventional magnetic head device.
FIG. 10
is a perspective view of the magnetic head device shown in
FIG. 9
, taken from the other side. The elastic members
2
are punched from an electrically conductive thin metal sheet of, for example, phosphor bronze or BeCu. The fastening member
3
, illustrated in
FIGS. 9 and 10
, connects the magnetic head device
1
to an optical head device
91
(illustrated in FIG.
13
). The fastening member
3
is molded in one piece using a synthetic resin. A slider
5
is molded in one piece from synthetic resin and attached to the front end portion of the pair of elastic members
2
. A head-supporting member
6
is molded around the pair of elastic members
2
in one piece using synthetic resin.
FIG. 12
is a side elevation of a system for applying a magnetic field, which is arranged in the slider
5
of
FIGS. 9
to
11
. A magnetic pole core
32
is E-shaped and formed from magnetic material such as a ferrite. A coil
4
is wound around the central magnetic pole
32
a
of the magnetic pole core
32
. The coil
4
and the magnetic pole core
32
apply a magnetic field, and are fixed to the slider
5
. A sliding portion
52
protrudes more towards the optomagnetic disk than the central magnetic pole
32
a
of the magnetic pole core
32
, and slides on the optomagnetic disk.
The sliding portion
52
protrudes from the front end side of the slider
5
opposing the base end side of the elastic members
2
. The slider
5
has a second elastically deformable portion
8
of the elastic members
2
in its center. As will be explained further below, when the slider
5
and the head-supporting member
6
are rotated away from the optomagnetic disk
100
, the slider
5
abuts a rotation orientation control arm
84
. A contacting portion
53
is formed on the front end side of the slider
5
and controls the rotational orientation of the slider
5
relative to the head-supporting member
6
. When the slider
5
abuts the rotation orientation control arm
84
, it rotates around the second elastically deformable portion
8
.
The portion of the pair of elastic members
2
between the fastening member
3
and the head-supporting member
6
is a first elastically deformable portion
7
. There is no synthetic resin molded around the first elastically deformable portion
7
, so that the elastic members
2
in this portion are exposed. The first elastically deformable portion
7
is the rotation center when the head-supporting member
6
and the slider
5
are rotated forward or away from the optomagnetic disk
100
.
Moreover, the portion of the elastic members
2
between the slider
5
and the head-supporting member
6
is the second elastically deformable portion
8
. There is no synthetic resin molded around the second elastically deformable portion
8
, so that the elastic members
2
in this portion are exposed. The system for applying a magnetic field is attached to the slider
5
. The slider
5
follows the swaying of the rotating optomagnetic disk
100
, so that the second elastically deformable portion
8
moves elastically back and forth.
The resilience of the first elastically deformable portion
7
and the second elastically deformable portion
8
forces the slider
5
against the optomagnetic disk
100
. Thus, the slider
5
slides on the rotating optomagnetic disk
100
with a certain sliding pressure. For the resilient force, a force is sufficient if it causes the slider
5
to glide on the optomagnetic disk
100
with a certain sliding pressure and without separating too much from the surface of the optomagnetic disk
100
. When the resilient force is too large, the sliding friction between the slider
5
and the optomagnetic disk
100
increases, and may result in considerable wear of the slider
5
and the optomagnetic disk
100
.
Therefore, the resilience and the mechanical strength of the first and the second elastically deformable portions
7
and
8
should be restricted to relative small values. For this reason, the first and the second elastically deformable portions
7
and
8
are formed as plate springs of thin phosphor bronze, for example.
In such a magnetic head device, however, the cantilevered head-supporting member
6
is formed of a thin plate spring with insufficient mechanic strength. Thus, when a shock is applied to the magnetic head device, the load on the cantilevered head-supporting member
6
can easily surpass the elastic limit, so that the head-supporting member
6
is deformed. Especially, when a shock is applied to the head-supporting member
6
, the load concentrates on the base end, and the first elastically deformable portion
7
may deform considerably.
This danger of easy deformation as a result of a shock is the same even when the magnetic head device is built into an optomagnetic recording/reproducing device. In this case, if a shock is applied to the optomagnetic recording/reproducing device, the shock is transmitted to the magnetic head device, and the first elastically deformable portion
7
may be deformed easily.
To withstand such shocks, the head-supporting member
6
is provided with a connecting arm
76
, as shown in
FIGS. 9-11
,
13
and
14
. This connecting arm
76
is provided at one side of the base end of the head-supporting member
6
near the fastening member
3
and extends in the longitudinal direction of the head-supporting member
6
. The connecting arm
76
is provided with a weight
77
on its end.
The weight
77
relocates the center of gravity of the head-supporting member
6
, which is supported by the fastening member
3
via the first elastically deformable portion
7
, to a spot nearer the first elastically deformable portion
7
. In other words, the connection arm
76
extends the head-supporting member
6
beyond the first elastically deformable portion
7

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