Magneto-optical head and method of making coil for the same

Details Magneto-optical head and method of making coil for the same Magneto-optical head and method of making coil for the same

2001-02-27

2003-09-09

Klimowicz, William (Department: 2652)

Dynamic information storage or retrieval

Storage or retrieval by simultaneous application of diverse...

Magnetic field and light beam

C369S013330

Reexamination Certificate

active

06618330

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magneto-optical head used for writing data to or reading data from a magneto-optical data storage medium. The invention also relates to a method of making a coil used for such an MO head.
2. Description of the Related Art
As is known, a magneto-optical disk stores data magnetically, like a hard disk. Writing to an MO disk is first done by heating a portion of the disk with a laser beam. When the disk medium reaches a certain temperature (known as Curie temperature) it loses its magnetic coercivity. Then, with the use of an MO read/write head, a magnetic field is applied to the heated portion, thereby reorienting the magnetic field of the appropriate domains. This means that the data is stored.
The recorded data is read from the disk using a polarized laser beam. When the polarized light hits the magnetic domains on the disk, the direction of polarization is altered, in accordance with the direction of the magnetic field of the domain. In this way, the differences in the magnetic orientation of the domains are detected, whereby the data can be read.
A conventional MO head is disclosed in JP-A-2000-76724 for example. As shown in
FIG. 11
of the accompanying drawings, the conventional MO head includes an objective
90
and a transparent plate
91
which are carried by a nonillustrated slider. The plate
91
is provided with a downward, transparent projection
92
aligned with the optical axis Ca of the lens
90
. The projection
92
has substantially the same refractive index as the plate
91
. Around the projection
92
is provided a coil
93
consisting of two conductive patterns
93
a
for generating a required magnetic field. The coil
93
is covered by a transparent insulating layer
97
.
In operation, as shown in
FIG. 12A
, a laser beam passes through the lens
90
and the projection
92
, and reaches the MO disk D, to form a small laser spot Ls. In the figure, the distance between the lower surface of the plate
91
and the upper surface of the disk D is designated by h. The diameter of the laser beam passing from the plate
91
to the projection
92
is designated by D
1
.
Due to the projection
92
, the diameter of the laser beam passing through the plate
91
can be made smaller than when no such projection is provided. Specifically, without the projection
92
, the laser beam is refracted to a certain degree upon leaving the plate
91
into the air, as shown in FIG.
12
B. To compensate for the refraction and form an appropriately small laser spot on the disk D, the diameter D
2
of the laser beam needs to be larger than the diameter D
1
of
FIG. 12A
(here the distance between the plate
91
and the disk D is supposed to be the same for the two cases shown in
FIGS. 12A and 12B
)
With the projection
92
, however, the laser beam is allowed to travel straight upon leaving the plate
91
, as shown in
FIG. 12A
, whereby the diameter D
1
is relatively small. Accordingly, the inner diameter of the coil
93
is reduced, which is advantageous to generating a required magnetic field with a smaller amount of current.
Though having such an advantageous feature, the conventional MO head has a downside as well. First, it takes an extra time to form the projection
92
on the plate
91
. Second, it may be difficult to form the projection
92
with accuracy. Third, the inner diameter of the coil
93
cannot be made smaller than the diameter of the projection
92
.
Another example of conventional MO head is disclosed in JP-A-10(1998)-320863. As shown in
FIG. 13
of the accompanying drawings, the MO head includes an objective lens
90
formed integral with a projection
92
, and a coil
93
arranged around the projection
92
. Clearly, this conventional MO head also suffers the same problems as the MO head of FIG.
11
.
SUMMARY OF THE INVENTION
The present invention has been proposed under the circumstances described above. Therefore, an object of the present invention is to provide an MO head capable of applying a desired magnetic field to the heated portion of the disk more efficiently than is conventionally possible. Another object of the present invention is to provide a method of making a coil used for an MO head.
According to a first aspect of the present invention, there is provided a magneto-optical head including: a slider held in facing relation to a storage medium; an objective lens supported by the slider for concentrating light rays; a coil provided with a center through which the light rays pass, the coil including a first conductive pattern and a second conductive pattern which is closer to the storage medium than the first conductive pattern is; and a transparent insulating layer enclosing the coil. The second conductive pattern is smaller in inner diameter than the first conductive pattern. The insulating layer is arranged to fill the center of the coil.
In accordance with a preferred embodiment, the MO head may further include a transparent substrate disposed between the objective lens and the storage medium, and the coil may be provided on this substrate.
Preferably, the substrate and the insulating layer may have substantially the same refractive indexes.
Preferably, the transparent substrate may be provided with via-holes connected to the first and the second conductive patterns.
For reducing the overall size of the MO head, the first conductive pattern may be embedded in the transparent substrate.
In accordance with another preferred embodiment, the coil may be directly provided on the objective lens.
Preferably, each of the first and the second conductive patterns may be provided with a plurality of turns.
Preferably, the turns of the first conductive pattern may be offset radially of the coil from the turns of the second conductive pattern.
Preferably, the coil may include a connecting piece for connecting an inner turn of the first conductive pattern to an inner turn of the second conductive pattern.
Preferably, the coil may further include a first outgoing line connected to an outer turn of the first conductive pattern, and a second outgoing line connected to an outer turn of the second conductive pattern.
In addition to the first and the second conductive patterns, the coil may include third and fourth conductive patterns arranged between the first and the second patterns, wherein the third and the fourth conductive patterns are smaller in inner diameter than the first conductive pattern but greater in inner diameter than the second conductive pattern.
When the four conductive patterns are used, the coil may be provided with three auxiliary connecting pieces: a first connecting piece for connecting an inner end of the first conductive pattern to an inner end of the third conductive pattern, a second connecting piece for connecting an outer end of the third conductive pattern to an outer end of the fourth conductive pattern, and a third connecting piece for connecting an inner end of the fourth conductive pattern to an inner end of the second conductive pattern.
According to a second aspect of the present invention, there is provided a method of making a coil for a magneto-optical head. The method may include the steps of: forming a first conductive pattern on a transparent substrate; forming a first transparent insulating layer filling a center of the first conductive pattern; forming a second conductive pattern on the first insulating layer, the second conductive pattern being smaller in inner diameter than the first conductive pattern; and forming a second transparent insulating layer filling a center of the second conductive pattern.
Preferably, the method may further include the step of flattening a surface of the first insulating layer before the second conductive pattern is formed.
In accordance with a preferred embodiment, the method may further include the step of forming a first recess in the substrate for accommodating the first conductive pattern in the substrate.
In accordance with another preferred embodiment, the step of forming the second conductiv

Affiliated with

Also associated with

Rating

Magneto-optical head and method of making coil for the same does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Magneto-optical head and method of making coil for the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magneto-optical head and method of making coil for the same will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3085433