JPH03260936A - Magneto-optical disk device for magnetic field modulated overwrite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding a magneto-optical disk device for information recording that performs overwriting by magnetic field modulation, a magnetic head that approaches a focal point on the surface of a magneto-optical recording medium and obtains a required magnetic field strength is provided. A light beam is irradiated through an objective lens onto a magneto-optical disk medium, which consists of a magnetic path layer, a magneto-optical recording medium, and a transparent protective film, which are laminated in this order on at least one side of a disk substrate. A magnetic field modulation overwrite magneto-optical disk device comprising: an optical head for recording/reproducing data; and a magnetic head for generating a magnetic field necessary for the recording; It is composed of an annular coil wound around a central pillar of a core, and a tapered light passage hole is provided in the central pillar in a non-contact manner along the outer edge of the condensed light beam of the objective lens for calibration. .

[Industrial application field]

The present invention relates to a magneto-optical disk device for recording information that performs overwriting by magnetic field modulation, and more particularly to the structure of a magnetic head attached to an optical head.

Magneto-optical recording and reproducing devices are a field in which the market is rapidly expanding from recording and reproducing image information to those capable of recording codes for computers due to their large capacity, interchangeability, and high reliability.

[Conventional technology]

FIG. 4 shows a sectional view of a main part of a conventional magneto-optical recording head. This conventional example is published in Japanese Patent Application Laid-Open No. 60-29904. In the figure, 1 indicates an actuator that controls the focus and tracking of the objective lens 2, and 3
A winding frame a is fixed to a movable part of the actuator 1 including the objective lens 2, and is made of a soft magnetic material in the shape of a bot core.

An annular coil 4 is wound around the center column of the pot-shaped portion, a light passage hole is provided in the center column, and the magnetic head 3 is configured together with the winding frame 3a. 5 to 8 indicate the structure and layers of the magneto-optical disk medium, where 5 is a transparent protective film, 6 is a magneto-optical recording medium, and 7 is a magnetic path layer (also called a turn bus layer, made of ferrite or permalloy). The magnetic thin film is formed by sputtering or the like to a thickness of several to several tens of micrometers),
8 is a disk substrate. A double-sided magneto-optical disk medium in which disks are stacked symmetrically around the disk substrate 8 is also known.

9 is an objective lens 20) optical axis; 10 is an optical head;
10a is a frame of the optical head 10 that holds the fixed part of the actuator 1. When a necessary current is passed through the annular coil 4, a magnetic path shown by a broken line is formed, and a magnetic field necessary for recording is generated at a spot focused on the magneto-optical recording medium by the objective lens 2.

Figures 5 to 8 show the combination of the annular coil (bias coil) and winding frame (core) that constitute the magnetic head.
Types 1 to 4) (a) shape diagram shown on the left and (b) magnetic field strength characteristics on the recording layer corresponding to the shapes shown on the right; these characteristics are the same. Coil dimensions of the number of turns When a constant drive current is passed under predetermined conditions of the core dimensions and the distance to the magneto-optical recording medium facing the magneto-optical recording medium, the optical axis position on the surface of the magneto-optical recording medium is set to zero, and the radial distance unit mm is It is a characteristic diagram which measured the distribution of magnetic field strength (unit: Oe).

First, in type 1 shown in Fig. 5, when the annular coil 4 is an air-core coil, the magnetic field strength shows a maximum value of 1250e up to about 3 mm from the optical axis position on the plane of the magneto-optical recording medium. is weak.

In the case of type 20) in FIG. 6, which has a dish-shaped core 15, the maximum value is only slightly increased compared to that in FIG.

In the type 3 hollow cylindrical core 16 shown in FIG. 7, the intensity at the optical axis position on the magneto-optical recording medium surface is slightly reduced compared to that in FIG.
On the contrary, a peak value of 15 (10e) is shown at a position 6fflI11 radius away (position facing the core).

In the type 4 bottomed double cylindrical core 17 shown in FIG.
Compared to FIG. 5, the intensity at the optical axis position on the surface of the magneto-optical recording medium further decreases slightly, and conversely shows a peak value of 18 (10e) at a position 6 radius apart (position facing the core).

Since magneto-optical disk devices require a magnetic field of a predetermined intensity at the focal point on the surface of the magneto-optical recording medium during recording, -
It can be seen from the comparison results described in Section 3 that types (1) and (2) are advantageous. Further, since the coil used for this requires a high transfer rate, that is, a high magnetic field reversal frequency, there is a restriction that the inductance cannot be increased.

[Problem to be solved by the invention]

In the structure of the conventional magnetic hand 3, types 1 to 2 are advantageous for the focal position on the surface of the magneto-optical recording medium, but they have the disadvantage that a strong magnetic field strength cannot be obtained if the number of windings of the coil is constant. In addition, in types 3 and 4, the magnetic field strength at the focal point on the magneto-optical recording medium surface decreases, and a strong magnetic field strength is obtained in a ring shape at the position where the core faces the magneto-optical recording medium surface, deviating from the focal position. Therefore, it has some undesirable drawbacks.

The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a magnetic head that can obtain a required magnetic field strength close to the focal point on the surface of a magneto-optical recording medium.

[Means to solve the problem]

FIG. 1 shows an embodiment of the invention. At least one side of the disk substrate 8 has a magnetic path layer 7. For a magneto-optical disk medium formed by laminating a magneto-optical recording medium 6 and a transparent protective film 5 in this order,
Record data by irradiating a light beam through objective lens 2.
In a magnetic field modulation O/N write magneto-optical disk device comprising an optical throat 10 that performs reproduction and a magnetic head 20 that generates the magnetic field necessary for recording, the magnetic throat 20 is pot-shaped. It is composed of a core 11 and an annular coil 4 wound around a central pillar 11a of the pot-shaped core, and is perforated in the central pillar 11a in a non-contact manner along the outer edge of the condensed light beam of the objective lens 20). It is configured by providing a tapered light passage hole 11b.

[For production]

In FIG. 1, the tip of the central column 11a on the pore side of the tapered light passing hole 11b is different from that of the conventional example in FIG.
Since it is closer to the focusing optical axis than the tip of the core 15 shown in FIG. I can do it. This allows a desired magnetic field strength to be obtained with a low-inductance coil, and furthermore, by fixing the pot-shaped core 11 to the frame 10a of the optical head, the mass of the movable part of the actuator 1 can be reduced.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Note that, in order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and repeated explanation thereof will be omitted.

FIG. 1 shows a sectional view of a main part of an embodiment of the present invention.

In the figure, a magnetic head 20 generates a magnetic field necessary for recording.
is composed of a pot-shaped core 11 made of a highly magnetic material and formed into a bottomed double cylindrical shape, and an annular coil 4 wound around a central column 11a of the pot-shaped core 11.
Objective lens 20) a has a tapered light passage hole 11b that is formed in a non-contact manner along the outer edge of the condensed light beam.

As shown in the figure, the shape of the core extends along the outer edge of the condensed light beam from the objective lens 20) to near the focal point connected to the magneto-optical recording medium 6, so that a magnetic path is generated between the core and the magnetic path layer 7. is formed as shown by the broken line, and compared to the magnetic field strength distribution diagram in FIG. 8(b), the peak of the magnetic field strength is
, the necessary magnetic field can be easily obtained by concentrating near the focal position (in the direction in which the radial position approaches zero).

Although this magnetic head 20 can be fixed to the winding frame 3a as in the conventional example, it is fixed to the frame 10a of the optical head in order to reduce the weight of the movable part of the actuator 1 and facilitate minute control. The structure is more effective.

FIG. 2 shows an embodiment of the floating slider-mounted type of the present invention, in which FIG. 2(a) is a front sectional view, and FIG. show. In each figure,
Reference numeral 12 is equivalent to a flying slider used in magnetic disk drives, etc., and is made of a non-magnetic material, and is swingably attached to the frame of an optical head (not shown). Reference numeral 12a denotes a pair of normal floating rails, and a pot-shaped core 11 is mounted so as to be buried therein as shown in the figure on the center line 1 0 - sandwiching the floating rails.

After the light beam passes through the objective lens 2 located above the floating slider 120), a tapered beam iJ! ! Overhole 1
1b, and further passes through a tapered light passing hole 12b formed in the bottom plate of the floating slider 120 on an extension of the tapered light passing hole 11b, and is irradiated onto the magneto-optical recording medium 6.

Since a magnetic path is formed by a gear corresponding to the slider flying height, by passing a predetermined current through the annular coil 4, a magnetic path generated between it and the magnetic path layer 7 is formed as shown by the broken line.
As in the case of FIG. 1, the necessary magnetic field can be easily obtained by concentrating near the focal point of the light beam.

Since the medium surface of the magneto-optical recording medium 6 is provided with a transparent protective film 5 having a thickness of 2 (10 - or less), damage caused by contact with the slider can be avoided.Of course, magneto-optical disk media may be formed on both sides. Since the magnetic path layer 7 is provided on the magneto-optical disk medium, a magnetic path is formed at a close distance, and as a result, the number of turns of the annular coil 4 can be reduced, and the excitation current can be reduced.

The diameter of the annular coil 4 is preferably 1 mm or less, and the slider flying height is suitably 10 mm or less.

In addition, the light passing hole 12 on the bottom surface of the floating slider 120)
If the opening b is closed with a transparent plate 13 made of a transparent material so as to be flush with the bottom surface thereof, it is effective to prevent the occurrence of turbulence and to stably float the floating slider 12.

FIG. 3 shows a modified embodiment of the present invention, in which a floating slider 12 shown in FIG. 2 is provided with an annular coil 4, an objective lens 2, and an actuator 14 for tracking control of the objective lens 2. It's at the bottom. in this case,
Since the depth of focus of the objective lens 20) is about ±0.5 degrees, it is preferable that the flying height of the flying slider 120) is set to about 2 subs. In this example, the flying height of the flying slider I20) follows the surface runout of the magneto-optical disk medium and is maintained approximately constant, and the focus of the light beam is automatically maintained, so the objective lens 20) Control functions can be omitted.

Therefore, the actuator 14 only needs to have a tracking control function, and the weight can be reduced.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the required magnetic field strength can be obtained close to the focal point on the surface of the magneto-optical recording medium, and the number of turns of the annular coil can be reduced, thereby improving the magnetic field reversal speed. It has the effect of

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 2 shows an embodiment of a flying slider-mounted type of the invention. FIG. 3 shows a modified embodiment of the invention. FIG. 4 shows a cross section of a main part of a conventional magneto-optical recording head. Figure 5 shows the magnetic field strength characteristics of bias coil/type (1), Figure 6 shows the magnetic field strength characteristics of bias coil/type (2), Figure 7 shows the magnetic field strength characteristics of bias coil/type (3), FIG. 8 shows the magnetic field strength characteristics of bias coil/type (4). 1 to 3, 2 is an objective lens, 4 is a circular coil, 5 is a transparent protective film, 6 is a magneto-optical recording medium, 7 is a magnetic path layer, 8 is a disk substrate, 10 is an optical head, and 10a is a In the frame of the optical head, 11 is a pot-shaped core, 11a is a center column, 11b is a light passage hole, 12 is a floating slider, 13 is a transparent plate, 14 is an actuator, and 20 is a magnetic head. 3-4

Claims (5)

[Claims] (1) At least one side of the disk substrate (8) has a magnetic path layer (
7) Record/reproduce data by irradiating a light beam through an objective lens (2) onto a magneto-optical disk medium formed by laminating a magneto-optical recording medium (6) and a transparent protective film (5) in this order. In the magnetic field modulation overwrite magneto-optical disk device, the magnetic head (20) is equipped with a pot-shaped core. (11), and an annular coil (4) wound around the central pillar (11a) of the pot-shaped core, and the central pillar (11a) has an outer edge of the condensed light beam of the objective lens (2). 1. A magnetic field modulation overwrite magneto-optical disk device, characterized in that a tapered light passage hole (11b) is provided in a non-contact manner. (2) The magnetic field modulation overwrite magneto-optical disk device according to claim 1, wherein the pot-shaped core (11) is fixed to the bottom of the frame (10a) of the optical head. (3) The magnetic head (20) is connected to the objective lens (2).
) and the transparent protective film (5).
2. The magnetic field modulation overwrite magneto-optical disk device according to claim 1, wherein the magnetic field modulation overwrite magneto-optical disk device is installed in a floating slider (12) that is swingably provided with respect to the magnetic field modulation overwrite magneto-optical disk device. (4) The opening of the light passage hole (11b) on the bottom surface of the floating slider (12) is connected to a transparent plate (
13. The magnetic field modulation overwrite magneto-optical disk device according to claim 1, wherein the magnetic field modulation overwrite magneto-optical disk device is closed in the same plane. (5) The annular coil (4) is attached to the floating slider (12).
), the objective lens (2), and the objective lens (2)
5. The magnetic field modulation overwrite magneto-optical disk device according to claim 3, further comprising an actuator (14) for tracking control.