Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Reexamination Certificate
2001-06-15
2003-05-06
Psitos, Aristotelis M. (Department: 2651)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
C369S013040, C369S300000, C369S247100
Reexamination Certificate
active
06560169
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magneto-optical recording and reproduction device usable in a magneto-optical disk apparatus such as, for example, a mini disk apparatus.
2. Description of the Related Art
FIG. 12
shows a conventional magneto-optical recording and reproduction device
400
used in a magneto-optical disk apparatus such as a mini disk (hereinafter, referred to as an MD) apparatus or the like. A magneto-optical disk
12
includes a magneto-optical recording medium
12
a
and a transparent substrate
12
b.
The magneto-optical recording and reproduction device
400
includes an optical pickup housing
7
accommodating an optical pickup
17
for emitting a laser beam
4
, a magnetic head
16
used for magnetic field modulation recording, a slidable member
3
(magnetic head slider), and a suspension
8
for pressing the slidable member
3
against the magneto-optical disk
12
with a constant load.
The optical pickup
17
includes an objective lens
5
for focusing the laser beam
4
which optically reproduces information from the magneto-optical disk
12
and which is used to raise the temperature of the magneto-optical recording medium
12
a
of the magneto-optical disk
12
when recording information to or erasing information from the magneto-optical disk
12
, or when performing recording and erasing at the same time. The optical pickup
17
also includes a photodetector
6
, and an actuator
18
for driving the objective lens
5
in a focusing direction or a radial direction of the magneto-optical disk
12
to adjust the position of the objective lens
5
.
The magnetic head
16
includes a magnetic core
1
formed of a magnetic material such as Mn—Zn ferrite or the like, and a coil
2
. The magnetic head
16
applies a magnetic field to a portion of the magneto-optical recording medium
12
a
which has had its temperature raised as described above by the laser beam
4
.
The magneto-optical recording and reproduction device
400
further includes a magnetic head connection arm
9
for connecting the suspension
8
and the optical pickup housing
7
to each other, a guide shaft
10
which is a moving mechanism for moving the optical pickup housing
7
in a radial direction of the magneto-optical disk
12
, and a subguide
11
for supporting the optical pickup housing
7
. The magneto-optical recording and reproduction device
400
is incorporated into a chassis
14
.
During an information recording or reproduction operation of the magneto-optical recording and reproduction device
400
, a recording media surface of the magneto-optical disk
12
moves up and down in accompaniment with rotations of the magneto-optical disk
12
. The magneto-optical recording and reproduction device
400
is structured to, during the information recording or reproduction operation, cause the actuator
18
to move the objective lens
5
up and down so as to follow the up-and-down movement of the recording media surface, so that the laser beam
4
is continuously focused on the recording media surface in a satisfactory manner.
During the information recording operation, the magnetic head
16
is on the recording media surface of the magneto-optical disk
12
. For starting the information reproduction operation, the magnetic head
16
is lifted up from the recording media surface of the magneto-optical disk
12
. Such an up-and-down movement of the magnetic head
16
is performed in order to extend the life of the magneto-optical disk
12
and the magnetic head
16
and reduce power consumption at a spindle (not shown) for rotating the magneto-optical disk
12
. The magnetic head
16
is lifted up and lowered by, for example, a rotation mechanism
13
, which is a hinge mechanism attached to the magnetic head connection arm
9
, using a lifting plate (not shown) or the like. Currently, this structure is commonly used in magneto-optical recording and reproduction devices using a magnetic head.
In recent years, the size and weight of a magneto-optical disk apparatus have been reduced. For example, a disk used in an MD apparatus has a diameter which is as small as 64 mm. Techniques for reducing the size and the thickness of a magneto-optical recording and reproduction device have been actively developed to fit the device to the size of the disk. Furthermore, the magnetic field generation region in the magnetic head
16
for magneto-optical recording has been reduced due to the improvement in the recording density and data transmission rate. Therefore, extremely high level positioning and servo techniques of the optical pickup
17
are required.
When the size and the thickness of a magneto-optical disk apparatus are reduced, the weight of a device for driving the magneto-optical disk apparatus is also reduced, thus increasing the magnitude of vibration transmitted to a disk mounted on the magneto-optical disk apparatus. For example, referring to
FIG. 12
, the actuator
18
moves the objective lens
5
so as to follow the up-and-down movement of the magneto-optical disk
12
. As a result, the actuator
18
vibrates, and the vibration of the actuator
18
is conveyed to the magnetic head connection arm
9
. Since the vibration of the magnetic head connection arm
9
is transmitted to the magneto-optical disk
12
, the magneto-optical disk
12
vibrates strongly. This causes a disturbance or a focus error in a focus servo system. The disturbance generated in the focus servo system can cause an adverse influence on the recording and reproducing characteristic of the magneto-optical recording and reproduction device. In the worst case, a recording and reproduction operation becomes impossible because the servo mechanism cannot provide sufficient control of the optical pickup
17
and the objective lens
5
.
The data transmission rate during the recording and reproduction operation is required to be as high as possible. In order to obtain a higher speed than conventionally possible, inductance of the magnetic head
16
should be reduced. Such a reduction in inductance decreases the size of a magnetic pole of the magnetic head
16
, which reduces the magnetic field generation region. Therefore, the position of the magnetic pole with respect to a laser spot on the magneto-optical disk
12
irradiated with the laser beam
4
is required to be more precise.
When reproducing the information stored on the magneto-optical disk
12
or taking out the magneto-optical disk
12
from the magneto-optical apparatus
400
, the magnetic head
16
generally has to be significantly lifted up from the recording media surface of the magneto-optical disk
12
. As shown in
FIG. 12
, the rotation mechanism
13
, such as a hinge mechanism or the like, is used to lift up the magnetic head
16
from the recording media surface of the magneto-optical disk
12
. Naturally, the hinge mechanism has some play. Therefore, the position of the magnetic pole with respect to the laser spot moves by a magnitude of this play. When this movement of the position is excessively large, the laser spot and the position of the magnetic pole are displaced from each other, resulting in the recording operation being impossible in the worst case.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a magneto-optical recording and reproduction device includes an optical pickup for irradiating a magneto-optical disk with a laser beam for performing at least one of information recording to a magneto-optical disk, information reproduction from the magneto-optical disk, and information erasure from the magneto-optical disk; a magnetic head for providing a magnetic field to a position of the magneto-optical disk irradiated with the laser beam for performing at least one of the information recording and the information erasure, the magnetic head being located opposite to the optical pickup with respect to the magneto-optical disk where the magneto-optical disk is mounted on the magneto-optical recording and reproduction device; a housing for accommodating the optical pickup; a
Miyake Tomoyuki
Nagatome Seiichi
Tanaka Toshiyuki
Conlin David C.
Edwards & Angell LLP
Jensen Steven M.
Psitos Aristotelis M.
Sharp Kabushiki Kaisha
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