JPS6353701A - Generating device for high frequency modulated magnetic field - Google Patents

Abstract

PURPOSE:To attain magnetic field generation to be suitably impressed on a magneto-optical recording medium, by providing a yoke part linked magnetically with a magnetic pole on the other end of a main magnetic pole, and arranged so as to enclose the main magnetic pole, and forming one end of the main magnetic pole in a convergent shape. CONSTITUTION:The titled device is constituted so that the main magnetic pole 2 being confronted with the magneto-optical recording medium on one end, and to generate a recording, or an erasing magnetic field, a winding 3 wound about the main magnetic pole, and to drive the main magnetic pole 2, and the yoke part 4 linked magnetically with the main magnetic pole 2, and arranged so as to enclose the main magnetic pole on the other end, are provided, and the tip part that is one end of the main magnetic pole, is formed in the convergent shape by forming a tapered part 6. And by setting the angle theta of the tapered part 6 of the main magnetic pole 2, for example, <=50 deg., more preferably, <=45 deg., it is possible to generate a more intensified magnetic field efficiently, and also, by setting the width (q) of a plane 7 at a range of 0.1-3mm, more preferably, 0.1-1mm, it is possible to generate the magnetic field suitable for magneto-optical recording with high density, etc., by suppressing the spread of a magnetic flux. In this way, the magnetic field to be impressed suitably on the magneto-optical recording medium can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a high frequency modulated magnetic field generator for applying a modulated magnetic field to a magneto-optical recording medium, and in particular to a high frequency modulated magnetic field generating device for applying a modulated magnetic field to a magneto-optical recording medium, and particularly for superimposing recording signals in a high frequency region in real time. The present invention relates to a high frequency modulated magnetic field generating device that enables writing (override).

B0 Summary of the Invention The present invention provides a high-frequency modulated magnetic field generator for applying a modulated magnetic field to a magneto-optical recording medium, in which one end of a main pole having a yoke portion at the other end and having a wire wound thereon is tapered. This shape improves the characteristics of magnetic field generation.

C9 Prior Art In magneto-optical recording and reproduction, one method of making override possible in real time is to perform recording using a magnetic field modulation method.

Here, the method of recording and erasing information signals using the magnetic field modulation method will be briefly explained with reference to FIG.
First, a laser device 101 for heating the magneto-optical recording medium 100 with a laser beam through a lens 102;
Recording and erasing are performed by a magnetic field generating device 103 that generates a magnetic field that is modulated according to an input signal. That is, the portion of the magneto-optical recording medium 100 to be recorded is heated by the laser device 101, and by applying a magnetic field to the heated portion by the magnetic field generator 103, it is magnetized in a predetermined direction, and this magnetization causes recording to be performed.・An abduction takes place.

D0 Problems to be Solved by the Invention The magnetic field generating device 103 described above can perform high-density recording by following the track defined on the magneto-optical recording medium 100 with high precision and moving at a constant pinch. Since this makes it possible to use a servo mechanism, a servo mechanism is used. Since it is necessary to operate the servo mechanism with high precision, it is desirable that the mounted magnetic field generating device be small and lightweight, and if it is small, power consumption can be reduced.

However, even if the magnetic field generator 103 is made smaller, a sufficient magnetic field strength (for example, on the order of several hundred (Oe)) is required to achieve a reliable override operation on the magneto-optical recording medium 100. is required, and real-time override cannot be achieved without sufficient magnetic field strength.

On the other hand, by increasing the signal current supplied to the magnetic field generating device 103, a magnetic field strength sufficient to cause magnetization reversal on the magneto-optical recording medium 100 can be obtained. However, in this case, heat generation occurs and the characteristics of the magnetic poles deteriorate, and when the temperature reaches the Curie point or higher, areas other than those that should be heated are also heated.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a high frequency modulated magnetic field generating device that achieves a reliable override operation on a magneto-optical recording medium with sufficient magnetic field strength without causing any adverse effects such as heat generation.

E8 Means for Solving Problems The present invention has a main magnetic pole that faces a magneto-optical recording medium at one end and generates a magnetic field for recording or erasing, and a main magnetic pole that is wound around the main magnetic pole to excite the main magnetic pole. A high frequency modulation device comprising a winding and a yoke portion magnetically coupled to the main magnetic pole at the other end of the main magnetic pole and arranged to surround the main magnetic pole, one end of the main magnetic pole having a tapered shape. A magnetic field generator solves the above problems.

F0 Effect In the high frequency modulated magnetic field generating device of the present invention, one end of the main magnetic pole is tapered, and therefore a strong magnetic field can be efficiently obtained on the central axis of the main magnetic pole. In addition, the yoke portions are coupled, suppressing the spread of the generated magnetic field and providing a magnetic field suitable for application to the magneto-optical recording medium.

Here, the tapered shape is a shape in which the diameter of the tip, which is one end of the main pole, is smaller than the diameter of the main pole part where the winding is applied. The fact that a strong magnetic field can be obtained can be explained from the following experimental example.

First, a high-frequency modulated magnetic field generator having a cross-sectional shape as shown in FIGS. 6 to 9 was manufactured, and the strength of the magnetic field generated when electricity was applied was determined. The main pole and yoke of the high-frequency modulated magnetic field generator shown in FIGS. 6 to 9 are made of nickel-zinc ferrite, and the diameter d of the tip, which is one end of the main pole, is a constant value (1 , 5φ), the height h of the main magnetic pole (indicated by h in Fig. 6) is 6.5 fins, and the width W of the yoke part (indicated by W in Fig. 6) is 6.5 fins, yoke The gap g between the magnetic pole and the main magnetic pole (indicated by g in FIG. 6).

) is 0.25 mm, and in the high-frequency modulated magnetic field generators shown in FIGS. 6 to 9, the diameters of the main magnetic pole portions to which windings are applied are 2.0φ, 1°5φ, and 1.0mm, respectively. 0φ
, 0.5φ.

The coil current for each of these high-frequency modulated magnetic field generators was assumed to be 10CA-T), and the results of staining by the floor element method are shown in Table 1.

(Below, blank space) Table 1 (The sample number corresponds to each figure number, and each data indicates the magnetic field strength of the high-frequency modulated magnetic field generator shown in each figure. Also, the unit of magnetic field strength is is Oe (Oersted).

) As is clear from Table 1, in the high frequency modulated magnetic field generator in which one end of the main pole is tapered as shown in Figure 6, the magnetic flux is focused at the tip of the main pole, It can be seen that a stronger magnetic field is generated. In addition, by forming the tapered shape, it is possible to suppress the spread of the magnetic field in the area facing the magneto-optical recording medium, and it is possible to perform high-density magneto-optical recording by applying a local magnetic field.

In Experimental Example 2, a high-frequency modulated magnetic field generating device having a cross-sectional shape as shown in FIGS. 10 to 13 was manufactured, and the intensity of the magnetic field generated when energized was similarly determined. In addition, in the high-frequency modulated magnetic field generator shown in FIGS. 10 to 13, the diameter d of the tip, which is one end of the main magnetic pole, is 1.5φ, 1.0φ, and 0.5, respectively.
φ, 0.3φ, the diameter of the main magnetic pole portion formed by the winding is 1.5φ, and the materials and other parts are the same as in the first experimental example.

The coil current for each of these high-frequency modulated magnetic field generators was set to 10 (A-T), and the results of simulation using the finite element method are shown in Table 2.

(The following is a margin) Table 2 (The numbers in the sample number correspond to each figure number, and each data indicates the strength of the magnetic field of the high-frequency modulated magnetic field generator shown in each figure. Also, the unit of magnetic field strength is is Oe (Oersted),
) As is clear from Table 2, the smaller the diameter d of the tip, the stronger the magnetic field generated, and by placing a high frequency modulated magnetic field generator having such a main pole facing the magneto-optical recording medium, Reliable recording and erasure is performed.

As explained above in Experimental Example 1 and Experimental Example 2,
By making the main magnetic pole tapered, a strong magnetic field can be efficiently generated.

G. Example Preferred embodiments of the present invention will be described with reference to the drawings.

The high frequency modulated magnetic field generating device of the present invention realizes real-time override in magneto-optical recording, and is a device that efficiently generates a strong magnetic field. The present invention will be explained below using specific examples. It goes without saying that the present invention is not limited to these Examples.

First, as shown in FIG. 1, the high-frequency modulated magnetic field generating device 1 of the first embodiment has a main body that faces a magneto-optical recording medium at one end and generates a magnetic field for recording or erasing. magnetic pole 2;
A winding 3 that is wound around the main magnetic pole 2 to excite the main magnetic pole 2; and a yoke that is magnetically coupled to the supranuclear magnetic pole 2 at the other end of the main magnetic pole 2 and is arranged to surround the main magnetic pole 2. A tapered portion 6 is formed at the tip, which is one end of the main pole, to form a tapered shape.

The main magnetic pole 2 is made of a sintered N1-Zn ferrite having a saturation magnetic flux density of 3500 G and an initial permeability of 3000 e, for example, and has a substantially cylindrical shape at the portion where the winding 3 is applied. A tapered portion 6 formed by cutting a cylindrical shape is formed at the tip of the main pole 2 facing the magneto-optical recording medium.

Here, to give an example of the specific dimensions of the main magnetic pole 2, the diameter of the main magnetic pole 2 to which the winding 3 is applied is 1.5
The height 2 of the φ1 cylindrical part is 4. Qmm, the axial height p of the tapered portion 6 is 0.8, and the top surface 7 facing the magneto-optical recording medium
are cut to each dimension with a width q of 0.70. A disk-shaped flange portion 8 is formed at the other end of the main pole 2 and functions as a part of the yoke portion 4, and its dimensions are equal to the width W.
is 6°5, and the thickness t is 1.2n.

In this way, the main magnetic pole 2 has a tapered shape, and as is clear from Comparative Experiment Example 1, which will be described later, the main magnetic pole 2 has a tapered shape.
The magnetic flux excited by the winding 3 is focused at the tip, and the high frequency modulated magnetic field generating device of this embodiment can generate a magnetic field suitable for magneto-optical recording. The angle θ of the tapered portion 6 of the main magnetic pole 2 (referring to the angle between the side surface of the tapered portion 6 and the axis of the main magnetic pole 2) is, for example, 50° or less, and more preferably 45° or less. By setting the width q of the top surface 7 to be in the range of 0.1 to 31 m, more preferably in the range of 0°1 to 1 m, the spread of the magnetic flux can be improved. This results in generation of a magnetic field suitable for high-density magneto-optical recording.

The winding 3 consists of approximately 10 thin conductive wires on the circumference of the main pole 2.
It is a wound wire, and a Litz wire or the like may be used.

The yoke portion 4 is formed using Ni--Zn ferrite, which is the same as the main magnetic pole 2 and has a saturation magnetic flux density of 3500 G and an initial magnetic permeability of 3000 e, and is used to form a magnetic path, so-called return path. Furthermore, even when the magneto-optical recording medium is placed close to each other, the spread of magnetic flux can be suppressed, and the yoke portion 4 is effective. The yoke portion 4 has a cylindrical shape, and the side of the yoke 4 facing the magneto-optical recording medium protrudes in the axial direction, and has a circular cutout in the center so that the main magnetic pole 2 faces. The diameter of the notched portion 11 is approximately 2.4 mm, and the length of the yoke portion 4 in the direction of the rotational symmetry axis is approximately 4 mm. Further, the outer diameter of this yoke 4 portion is approximately 4.7 fins, and the inner diameter is approximately 3.1 fins.

The high frequency modulated magnetic field generating device 1 of this embodiment can be used for a magneto-optical recording medium as shown in FIG.

That is, in FIG. 2, a magneto-optical recording medium 21 has a magneto-optical recording layer 23 formed on a substrate 22 made of a material such as polycarbonate resin, methacrylic resin, glass, etc., and a protective film 24 formed thereon.

The magneto-optical recording layer 23 is, for example, a Tb-Fe-Co film and has a thickness of approximately 1000 mm. Further, the retainer ff1bf is made of silicon nitride, silicon oxide, synthetic resin, or the like, and has a thickness of approximately 1 μm.

The high frequency modulated magnetic field generating device 1 of this embodiment is used for such a magneto-optical recording medium 21. The high-frequency modulated magnetic field generating device 1 generates the magneto-optical recording material J using a laser beam.
A laser device 25 for heating the W23 to a temperature higher than the Curie point is disposed opposite to the magneto-optical recording medium 21.

Here, the high frequency modulated magnetic field generating bag r! The distance C between L1 and the magneto-optical recording medium 21 may be about 0.05 to 3 fl, and more preferably about 0.1 to l mx.

Note that the shape of the yoke portion 4 is not limited to one extending in the direction of the main magnetic pole 2, and may be simply cylindrical or the like as long as it forms a magnetic path.

Furthermore, the material of the main pole 2 may be a low-loss soft magnetic material, and is not limited to Ni-Zn ferrite.

Regarding the magnetic field suitable for magneto-optical recording generated by the high-frequency modulated magnetic field generating device l as described above, in comparison with a device having a main magnetic pole that is not tapered before processing, with reference to FIG. explain.

Here, a device having a main magnetic pole that is not tapered before processing is a high-frequency modulated magnetic field generating device that has a main magnetic pole that is approximately cylindrical before the cutting portion 9 shown by the dotted chain line in Fig. 1 is cut out. It is a device.

In a comparative experiment, as shown in Fig. 3, the strength of the generated magnetic field was determined by varying the head distance between a device having a main magnetic pole without a tapered shape before processing and a high-frequency modulated magnetic field generating device 1 with a tapered shape after processing. Measurements were taken while changing the current applied to the winding 3 when C was 0.1 mm, 0.3 mm, and 0.5 m.

As is clear from FIG. 3, the head distance is 0. I
In any case of N, 0.3 Tsuru, or 0.5 Tsuru, and at any current value of 0 to 3 A, the intensity of the generated magnetic field is tapered. High-frequency modulated magnetic field generator 1 after processing
is larger, indicating that it is possible to supply a sufficient magnetic field for magneto-optical recording.

】”” Otsu Lti1. - Gai The high-frequency modulated magnetic field generator of the second embodiment is obtained by further cutting the tapered main pole, as shown in FIG.
It is a device that is miniaturized as a whole with a substantially conical tip.

As shown in FIG. 4, in the high frequency modulated magnetic field generating device 41 of the second embodiment, one end of the main magnetic pole 42 facing the magneto-optical recording medium is formed into a substantially conical portion 46, and the winding 43 and The yoke portion 44 is provided to have the functions of excitation and formation of a return path, as in the first embodiment. These materials, etc. are the same as those of the high frequency modulated magnetic field generator 1 of the first embodiment described above, but the specific dimensions of the main magnetic pole 42 are the diameter of the main magnetic pole 42 on which the winding 43 is applied. It is cut to have dimensions of 1°0 m1, the height l of the cylindrical portion 3.3 mm, and the axial height p of the conical portion 46 0.5 mm.

Note that a disk-shaped flange portion 4 is provided at the other end of this main pole 42.
8 is formed and functions as a part of the yoke portion 44, and its width W is 3.4n.

To explain the conical portion 46 here, the diameter of the conical portion 46 does not necessarily increase (decrease) at a constant rate along the axial direction.
It is not limited to a triangular cross-section, for example, it may be a conical portion with a bell-shaped cross-section.

In this way, the main magnetic pole 42 has a tapered shape, and as is clear from Comparative Experiment Example 2, which will be described later, the magnetic flux excited by the winding 43 of the main magnetic pole 42 is focused at the tip, and the present embodiment The high frequency modulated magnetic field generating device of this example can generate a magnetic field suitable for magneto-optical recording. Note that, similarly to the first embodiment, the angle θ of the conical portion 46 of the main magnetic pole 42 (refers to the angle between the side surface of the conical portion 46 and the axis of the main magnetic pole 42).

) is, for example, 50° or less, more preferably 45°
By doing the following, a strong magnetic field can be efficiently generated. In addition, in the case of tapering, the diameter of the tip (
This corresponds to the width q of the top surface 7 of the first embodiment. ) may be optimized by the distance C between the magneto-optical recording medium and the high-frequency modulated magnetic field generator.

Note that the high frequency modulated magnetic field generating device 41 of this second embodiment
can be used, for example, by the method shown in FIG. 2, similarly to the high frequency modulated magnetic field generating device 1 of the first embodiment.

A magnetic field suitable for magneto-optical recording generated by the high-frequency modulated magnetic field generating device 41 as described above will be described with reference to FIG. 5 in a comparison of the generated magnetic fields before and after processing.

Here, the main magnetic pole before processing is a high-frequency modulated magnetic field generator having a substantially cylindrical main magnetic pole before the cutting portion 49 shown by the dotted chain line in FIG. 4 is cut. , 5th
As shown in the figure, the strength of the magnetic field generated by a device having a main magnetic pole that is not tapered before machining and a high frequency modulated magnetic field generator 41 that has a tapered shape after machining is determined when the head distance C is 0°111. In each case of 0.3u, winding 43
Measurements were taken while changing the applied current.

As is clear from Fig. 5, the head distance C is
, 1 mm, Q, and 3 mm, and at any current value of 0 to 3 A, the strength of the generated magnetic field is tapered.
is larger, indicating that it is possible to supply a sufficient magnetic field for magneto-optical recording.

H. Effects of the Invention In the high-frequency modulated magnetic field generating device of the present invention, one end of the main magnetic pole is tapered, and therefore a stronger magnetic field is generated on the central axis of the main magnetic pole than when the main magnetic pole is simply cylindrical. can be obtained, and this magnetic field strength is sufficient for magneto-optical recording,
Furthermore, there is no need to supply more current than necessary, and heat generation can be suppressed. In addition, the yoke part is combined,
This suppresses the spread of the generated magnetic field and provides a suitable magnetic field to be applied to the magneto-optical recording medium.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a high-frequency modulated magnetic field generator according to the present invention, and FIG. 2 is a schematic diagram for explaining its usage.
FIG. 3 is a characteristic diagram of the relationship between the generated magnetic field and the winding applied current showing the results of Comparative Experiment Example 1, and FIG. 4 is a partially broken diagram of the high frequency modulated magnetic field generator according to the second embodiment of the present invention. The perspective view shown in FIG. 5 is a characteristic diagram of the relationship between the generated magnetic field and the winding applied current, showing the results of Comparative Experiment Example 2. 6 to 9 are cross-sectional views of the high-frequency modulated magnetic field generator used in Experimental Example 1, and FIG. 6 is sample number No. 6. FIG. 7 shows sample number No. 7. FIG. 8 shows sample number No. 8. FIG. 9 is a cross-sectional view of sample No. 9, and FIGS. 10 to 13 are cross-sectional views of the high-frequency modulated magnetic field generator used in Experimental Example 2.
Figure 0 is the sample number No. 10, and Figure 11 is the sample number No. 11 and 12 are cross-sectional views of sample numbers NO and 12, and FIG. 13 are cross-sectional views of sample numbers NO and 13, respectively. Further, FIG. 14 is a schematic diagram for explaining the principle of the magnetic field modulation method. 1.41... High frequency modulated magnetic field generator 2.42...
Main magnetic pole 3.43...Winding 4.44...Yoke part 6...Tapered part 46...Cone part Patent Applicant Sony Corporation agent Patent attorney Handmade Mima Sakae Tamura - Figure 3 Figure 4

Claims (1)

[Claims] A main magnetic pole that faces a magneto-optical recording medium at one end and generates a magnetic field for recording or erasing; a winding wound around the main magnetic pole to excite the main magnetic pole; A high frequency modulated magnetic field generating device comprising: a yoke portion magnetically coupled to the main magnetic pole at the other end and disposed so as to surround the main magnetic pole, one end of the main magnetic pole having a tapered shape.