Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Reexamination Certificate
2000-02-22
2004-05-25
Hudspeth, David (Department: 2651)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
C369S275200, C360S125020, C360S246200, C360S246000, C360S234700, C360S234800, C360S240000
Reexamination Certificate
active
06741526
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head device set in sliding contact with a surface of a disk such as a magnetic disk or a magneto-optical disk that is used as a recording medium. The present invention also relates to a recording/reproducing apparatus, which uses this magnetic head device.
Hitherto known is a recording/reproducing apparatus which uses, as a recording medium, a magneto-optical disk that comprises a substrate transparent to light and a magneto-optical recording layer formed on the substrate and composed of a perpendicular magnetizing film. The recording/reproducing apparatus comprises a disk drive mechanism, a magnetic head device, and an optical pickup device. The disk drive mechanism rotates the magneto-optical disk. The magnetic head device is arranged at one side of the magneto-optical disk to apply an external magnetic field to the magneto-optical recording layer of the disk. The optical pickup device applies a light beam to the magneto-optical recording layer provided on that side of the magneto-optical disk. In the recording/reproducing apparatus, the magnetic head device applies a magnetic field to the magneto-optical recording layer of the magneto-optical disk being rotated. The magnetic field thus applied has a direction modulated in accordance with the data signal to be recorded on the magneto-optical disk. In addition, the light beam emitted from the optical pickup device is converged and applied to the magneto-optical recording layer. Applied with the light beam, the magneto-optical recording layer is heated to Curie point. Those parts of the layer which have lost coersive force, are magnetized in the direction of the magnetic field applied from the magnetic head device. Thereafter, the temperature of the magneto-optical recording layer falls below Curie point as the light beam moves relative to the magneto-optical disk that keeps rotating. The direction of the magnetic field is fixed in the layer, whereby the data signal is recorded on the magneto-optical disk.
The magnetic head device for applying a magnetic field to the magneto-optical recording layer of the magneto-optical disk has a head section
101
as shown in FIG.
1
. The head section
101
comprises a magnetic field generating section
105
and a slider
106
. The slider
106
holds the magnetic field generating section
105
. The section
105
is composed of a magnetic core
102
, a coil
103
, and a bobbin
104
. The coil
103
is wound around the bobbin
104
.
The magnetic core
102
, which is one component of the magnetic field generating section
105
, comprises a center pole core
102
a
and a pair of side pole cores
102
b
, and a coupling section
102
c
. The side pole cores
102
b
are arranged on one side of the center pole core
102
a
and the other side thereof, respectively. The coupling section
102
c
connects the center pole core
102
a
and the side pole cores
102
b
at their proximal ends. The magnetic core
102
is shaped like letter E, as a whole. The bobbin
104
has an upper flange section
104
a
and a lower flange section
104
b
. Both flange sections
104
a
and
104
b
have a through hole, through which the center pole core
102
a
of the magnetic core
102
extends. The center pole core
102
a
of the magnetic core
102
passes through the holes of the flange sections and the coil
103
is wound around the center pole core
102
a
and made integral therewith. The magnetic field generating section
105
is thereby formed.
The slider
106
, which holds the magnetic field generating section
105
, is made of synthetic resin by means of injection molding. The slider
106
has a holder section
107
at its proximal end, for holding the magnetic field generating section
105
. The slider
106
has a sliding-contact section
108
extending from the distal end of the holder section
107
. The sliding-contact section
108
may be set into sliding contact with a magneto-optical disk. The holder section
107
has a recess, in which the magnetic field generating section
105
is fitted. Thus, the section
105
is connected to the holder section
107
.
In the head section
101
of the magnetic head device, a gap of about 0.1 mm is formed between the magnetic field generating section
105
and the holder section
107
. This is inevitable because the section
105
is fitted in the holder section
107
of the slider
106
. As a consequence, very little heat generated by the magnetic core
102
is radiated through the slider
106
.
In the head section
101
, the drive current and the record/transfer speed may be increased so that the magnetic field generating section
105
generates a more intense magnetic field. If so, the copper loss or iron loss of the coil
103
will increase, resulting in a further increase in the heat generated by the magnetic core
102
or the coil
103
. When the temperature of the magnetic core
102
or coil
103
rises to a value near Curie point, the magnetic permeability inevitably decreases, reducing the intensity of the magnetic field generated. Moreover, inter-layer short-circuiting occurs in the coil
103
when the temperature of the magnetic core
102
or coil
103
rises further, possibly resulting in burning. It is therefore impossible in the head section
101
to intensity the magnetic field or raise the record/transfer speed.
Furthermore, the head section
101
cannot increase the minimum intensity guaranteed for the magnetic field. This is inevitable because the tolerances of the components are limited since the magnetic field generating section
105
must be fitted in the slider
106
.
BRIEF SUMMARY OF THE INVENTION
Accordingly it is the object of the present invention to provide a magnetic head device in which heat can be efficiently radiated from the head section and the minimum intensity guaranteed for the magnetic field can be increased, and also a recording/reproducing apparatus which uses this magnetic head device.
A magnetic head device according to the present invention comprises a head section for applying a magnetic field to a disk. The head section includes a magnetic field generating section and a slider supporting the magnetic field generating section and is designed to be set in sliding contact with the disk. The magnetic field generating section has a magnetic core and a coil wound around the magnetic core. The magnetic field generating section generates the magnetic field and is embedded in and formed integral with the slider.
The head section has been formed by placing the magnetic field generating section at a prescribed position in a metal mold and then filling the metal mold with the material of the slider. The metal mold has a positioning projection. The projection is to abut on a distal end of the magnetic core, which opposes the disk, thereby to position the magnetic field generating section in a direction substantially perpendicular to the disk. A coil is wound around a bobbin that is mounted on the magnetic core. The bobbin has positioning projections to abut on sides of a metal mold for forming the head section, thereby to position the magnetic field generating section in a direction substantially parallel to the disk. Thus, the magnetic field generating section is arranged at the prescribed position in the metal mold.
A recording/reproducing apparatus according to the present invention comprises a magnetic head device. The magnetic disk device comprises a disk driving mechanism and a magnetic head mechanism. The disk driving mechanism rotates a disk. The magnetic head mechanism is provided on one side of the disk and comprises a head section for applying a magnetic field to a disk. The head section includes a magnetic field generating section and a slider supporting the magnetic field generating section and is designed to be set in sliding contact with the disk. The magnetic field generating section has a magnetic core and a coil wound around the magnetic core, for generating the magnetic field. The magnetic field generating section is embedded in and formed integral with t
Fujiie Kazuhiko
Koda Tomohiro
Netsu Naohiro
LandOfFree
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