Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Reexamination Certificate
2002-12-18
2004-11-30
Letscher, George J. (Department: 2652)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
Reexamination Certificate
active
06826130
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a structure for adjusting the position of the magnetic heads of optomagnetic disk devices for recording signals on or reproducing signals from optomagnetic disks, and to a method of adjusting the position.
BACKGROUND ART
As shown in
FIG. 13
, optomagnetic disk devices for minidisks comprise a head support unit
20
having a magnetic head
16
and an objective lens
10
which are opposed to each other as arranged on opposite sides of an optomagnetic disk
102
serving as a recording medium, with the lens
10
provided on a pickup
12
. Signals are recorded on or reproduced from the disk
102
while moving the head support unit
20
radially of the disk
102
.
The pickup
12
has a laser light source incorporated therein for projecting a laser beam as converged by an objective lens on the optomagnetic disk
102
. With the recording layer on the disk heated to a Curie temperature with the projected laser beam, alternating current is passed through the core of the magnetic head
16
to set up a magnetic field on the head
16
, whereby the recording layer is magnetized for signal recording. Signals are reproduced from the recording layer when the pickup
12
receives the laser beam projected on the layer and reflected therefrom.
To effectively apply the magnetic field of the magnetic head to the optomagnetic disk, there is a need to align the center of the head with that of the objective lens by position adjustment.
Accordingly, the position of the magnetic head is adjusted relative to the pickup by moving the head radially and tangentially of the disk.
A head support unit
20
adapted to adjust the position of the magnetic head
16
will be described with reference to
FIGS. 13 and 14
, and
FIG. 1
of the invention.
The pickup
12
is in engagement with a drive screw rod
54
mounted on an optomagnetic disk device
44
(see FIG.
1
), and is reciprocatingly movable radially of the disk (in the directions of arrows in
FIG. 1
) by the screw thrust of the drive screw rod
54
. Formed in one end of the pickup
12
are screw holes
22
for use in attaching a head arm
14
.
The head arm
14
comprises a support piece
62
attached to a bottom wall of the pickup
12
and adjustable in position, and a head lever
64
carrying the magnetic head
16
at its forward end, mounted on the support piece
62
and adjustable in position.
The support piece
62
has slits
24
parallel to a tangential direction of the disk and positioned in corresponding relation with the screw holes
22
in the pickup
12
. The pickup
12
and the support pieces
62
are held in engagement by screws
100
slidably fitting in the slits
24
and screwed in the screw holes
22
, respectively. With the screws
100
loosened, the support piece
62
is slidable tangentially of the disk relative to the pickup
12
. When the screws
100
are tightened up after the magnetic head
16
has been positioned in place tangentially of the disk, the heads of the screws press the support piece
62
against the pickup
12
to fix the support piece
62
to the pickup
12
. A screw locking agent is applied to the screw heads for preventing the screws
100
from loosening after the screws
100
have been tightened up.
The support piece
62
is bent upward at one end thereof, and the bent portion is provided at its upper end with a bracket
68
. The head lever
64
is supported by an adjusting screw
76
on the bracket
68
slidably radially of the disk and adjustably in position. The screw
76
is in screw-thread engagement with the bracket
68
. A compression spring (not shown) fitted around the adjusting screw
76
for biasing the head lever
64
radially of the disk is provided between two brackets of the support piece
62
and the head lever
64
. The head lever
64
is moved radially of the disk by turning the adjusting screw
76
, whereby the position of the magnetic head
16
is adjusted radially of the disk. The screw locking agent is applied to the portion of the screw
76
screwed in the bracket
68
to prevent the screw
76
from rotating.
For use with conventional minidisks, the magnetic head has a relatively large core size of about 700 &mgr;m×700 &mgr;m, so that the position of the magnetic head is adjustable satisfactorily under a microscope if accuracy is attained to some extent. Further even if the head is somewhat shifted when the fixing screws
100
are tightened up after the position adjustment of the head, the shift is considered permissible.
Low power consumption and a high magnetic field efficiency are required of the magnetic disk device, Advanced Strage MO (trademark: AS-MO), having a superhigh resolution and proposed in recent years. Accordingly, the core size of the magnetic head of this device is as small as up to about 400 &mgr;m radially of the disk and about 150 &mgr;m tangentially thereof, such that satisfactory performance is no longer available if the head is positioned in place under a microscope. Especially, some magnetic heads have a core size of about 100 &mgr;m tangentially of the disk, and the adjustment of the position of such a head in the disk tangential direction is of extreme importance.
However, the head support unit is so constructed that the support piece of the head arm is fastened to the pickup with the screws
100
after the position of the magnetic head has been adjusted tangentially of the disk as described above, so that the support piece
62
is likely to bend when fastened to the pickup as seen in
FIG. 15
(as indicated at P in the drawing). A residual stress is then likely to remain in the support piece
62
, possibly shifting the magnetic head during or after fastening. Further since the pickup
12
and head arm
14
are generally made from a metal plate by blanking, these components are each likely have a strain, with the result that the magnetic head as accurately adjusted in position will be shifted when subsequently fastened.
An object of the present invention is to provide an optomagnetic disk device having a magnetic head which can be positioned accurately especially tangentially of the magnetic disk, and a method of adjusting the position of the magnetic head.
DISCLOSURE OF THE INVENTION
The present invention provides an optomagnetic disk device
44
wherein a head support unit
20
comprises a pickup
12
having an objective lens
10
mounted thereon for converging a laser beam, and a head arm
14
connected to the pickup
12
, the head arm
14
having one end attached to the pickup
12
and a free end provided with a magnetic head
16
, the head arm
14
being adjustable in position relative to the pickup
12
so that the magnetic head
16
is opposed to the objective lens
10
on the pickup
12
, the head support unit
20
being movable radially of an optomagnetic disk,
the pickup
12
having at least one screw hole
22
for attaching the head arm
14
thereto,
the head arm
14
having a slit
24
opposed to the screw hole
22
of the pickup
12
and in parallel to a tangential direction of the disk,
a screw
26
being slidably fitted in the slit
24
of the head arm
14
and having a distal end screwed in the screw hole
22
of the pickup
12
,
an elastic member
30
being provided between the screw
26
and the head arm
14
for pressing the head arm
14
against the pickup
12
.
For use in the optomagnetic disk device
44
, the present invention provides a method of adjusting the position of the magnetic head
16
which method comprises moving the head arm
14
relative to the pickup
12
tangentially of the disk, with the head arm
14
pressed against the pickup
12
by the elastic member
30
, to adjust the position of the magnetic head
16
relative to the objective lens
10
on the pickup
12
and thereafter fixing the head arm
14
to the pickup
12
.
The head arm
14
as adjusted in position can be fixed to the pickup
12
by applying a screw locking agent.
Since the head arm
14
is attached to the pickup
12
, as pressed against the pickup
12
by the elastic member
30
, the head arm
14
can be mov
Letscher George J.
Sanyo Electric Co,. Ltd.
Westerman Hattori Daniels & Adrian LLP
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