JPS62172504A - Generator for high frequency modulation magnetic field - Google Patents

Abstract

PURPOSE:To realize sure over-write to a recording medium by winding a sheath wire comprising parallel connection insulated core wires onto a main magnetic pole of a low loss magnetic material whose one end is opposed to an optomagnetic recording layer so as to generate a high frequency modulation magnetic field preventing heat. CONSTITUTION:The sheath wires 3 wound on the main magnetic pole 2 are set of plural number of parallel connection insulated raw wires 5, the skin effect where much current flows to the surface only is prevented to suppress the heat from the wires 3. As the material of the magnetic pole 2, a low loss magnetic material is used, the magnetic field generation is conducted efficiently at the high frequency and by using the wires 3 made of the raw wires 5 and the disadvantage of heating is eliminated. Thus, stable recording and low power consumption are attained and over-write onto the optomagnetic recording medium is realized.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is an innovative method for magneto-optical recording and reproducing devices. 1! Regarding high-frequency modulation magnetic field generators for applying magnetic fields, especially high-frequency modulation that enables overwriting (so-called override) of recorded signals in real time in the high-frequency region! This invention relates to an li magnetic field generator.

[Summary of the invention]

The present invention provides a high-frequency modulated magnetic field generator for applying a modulated magnetic field used in a magneto-optical recording/reproducing device, in which a main pole made of a low-loss soft magnetic material is coated with a plurality of insulated wires connected in parallel to each other. By winding the conductive wire, adverse effects such as heat generation are prevented and high frequency characteristics are improved.

[Conventional technology]

Magneto-optical recording is a recording method in which information signals are written on a magneto-optical recording medium such as a magneto-optical disk using light and magnetism.

One of the characteristics of this magneto-optical recording is that it is possible to write an information signal incorrectly, so-called override. That is, in the magneto-optical recording method, new data can be written in an area on a magneto-optical recording medium where a recording pattern has already been written.

Such override is accomplished by reversing the biasing magnetic field. In order to make the bias magnetic field a strong magnetic field of a certain value or more, there are devices in which excitation is performed using a permanent magnet. This is a method of reversing the direction of the magnetic field by moving a permanent magnet mechanically, and the recording and erasing processes are performed separately. For example, after the -th erasing, the magnet is mechanically reversed and recording is performed in the area on the medium where the erasing was performed.

Another method is to separate the override operation and use an erasing device and a recording device independently.

That is, this is a method in which erasing and recording are performed at different locations on the magneto-optical recording medium.

[Problem that the invention seeks to solve]

However, with the above method, it is difficult to record in real time.

That is, in the method of mechanically reversing the permanent 61 stones W1, there is a limit to the operating speed, and high-speed operation is not easy.

In addition, in methods that use independent erasing and recording devices, they are placed at spatially separate locations, so especially in magneto-optical recording where recording is done at a high density, completely continuous recording cannot be achieved. .

On the other hand, overriding in real time is possible by recording using a magnetic field modulation method as shown in FIG. This includes a laser device 91 for heating the magneto-optical recording medium 90 with a laser beam via a lens 93, and a magnetic field generating device 92 for generating a magnetic field modulated in accordance with an input signal.

However, due to the demands for improved recording density and high-speed operation,
If a high frequency of, for example, several M Ilz is supplied to the magnetic field generating device 92, the desired magnetic field strength cannot be obtained, and the problem of heat generation occurs.

That is, in the magnetic field modulation method, in order to reverse the direction of magnetization of the magneto-optical recording medium 90, it is necessary to apply a constant strong magnetic field. However, when a high frequency signal is supplied, it becomes difficult to obtain a desired strong magnetic field due to the frequency characteristics of the core material of the magnetic field generator 92. On the other hand, by increasing the signal current supplied to the magnetic field generator 90, it is possible to obtain a magnetic field sufficient to reverse the magnetization. However, in this case, problems arise if heat generation occurs and the core characteristics deteriorate, or if the temperature reaches a temperature higher than the key point. As a result, the necessary strong magnetic field in the high frequency band cannot be obtained, and the heat from the magnetic field generator 90 affects the heating operation of the laser beam, making stable recording operations impossible.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention aims to provide a high-frequency modulated magnetic field generating device that prevents heat generation, generates a high-frequency variable Y41 field, and realizes a reliable override operation on a magneto-optical recording medium. .

[Means for solving problems]

The present invention has a main magnetic pole whose one end faces a magneto-optical recording layer and is made of a low-loss soft magnetic material, and a coated conductive wire consisting of a plurality of insulated wires connected in parallel to each other is wound around the main magnetic pole. The above-mentioned problems are solved by the high-frequency modulated magnetic field generator.

Here, the low one-membered soft magnetic material forming the main pole may be a material with low hysteresis and low eddy current loss, that is, a material with low resistivity and low coercive force.

For example, Ni-Zn ferrite can be used as an example of a low-loss magnetic material.

In addition, the multiple insulated wires that are wound around the main pole and connected in parallel to form the coated copper wire are thin enough that the skin effect does not become a problem at the frequency used, and the skin depth at the frequency used is small. The diameter may be approximately twice as large.

[Effect]

The coated conductor wire wound around the main pole is a collection of a plurality of insulated wires connected in parallel to each other.

For this reason? It is possible to prevent a skin effect in which a large amount of fl flow flows to the peripheral area, and therefore heat generation from the covered conductor can be suppressed. Furthermore, a low-loss magnetic material is used as the material for the main pole. Therefore, when used in combination with the rtI conducting wire made of the above-mentioned insulated wire, a magnetic field can be efficiently generated in a high frequency band, and there is no problem such as heat generation.

〔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 overwriting of data in real time in magneto-optical recording,
This device does not cause any adverse effects such as heat generation and has excellent high frequency characteristics.

First Embodiment First, as shown in FIG. 1, the high-frequency modulated magnetic field generating device l of the first embodiment has a main pole 2 whose one end faces the magneto-optical recording layer and is made of a low-loss soft magnetic material; It has a covered conducting wire 3 which is made up of a plurality of insulated wires 5 connected in parallel and is wound around the main magnetic pole 2. Further, a yoke 4 is attached in consideration of the case where a magneto-optical recording medium is placed close to each other, and a tapered portion 6 is formed in the main magnetic pole 2. The bottom portion 8 of the main magnetic pole 2 has a disc-like shape and protrudes in a direction perpendicular to the direction of the rotational symmetry axis of the main magnetic pole 2 in order to attach the yoke 4 thereto. In addition, a base 9 is provided to fix these members.
is attached under the bottom part 8 of the main magnetic pole 2, and the base 9
A sunrise line IO for wiring, etc. is formed in the area.

The main magnetic pole 2 has a substantially cylindrical shape made of a sintered body of Ni-Zn ferrite, which is a low demagnetizing material and has a saturation magnetic flux density of 3700 G and a coercive force of 0.550 e. is wound.

The tip 7 of this main pole 2 on the side facing the magneto-optical recording medium
is a circular plane, and the tip 7 and the main magnetic pole 2 are connected to each other.
A tapered portion 6, which is an inclined surface at an angle of 45″ with respect to the rotational symmetry axis of the main magnetic pole 2, is formed between the circumferential surface of Efficiently generates a magnetic field when magneto-optical recording media are brought close together,
This is effective when applying a magnetic field to a medium. The diameter of the cylindrical portion of the main pole 2 excluding the bottom 8 is approximately 3 tsuru, and the height is approximately 5 tsuru. Also, the diameter of the tip 7 is approximately l.
It is am.

The coated conductor 3 wound around the circumferential surface of the main magnetic pole 2 has a diameter of approximately 0.1 mm and is connected in parallel with an insulated wire 5 made of a low resistance material such as copper. , approximately'2
It is made up of three pieces tied together. Since the coated conductor 3 is made of an insulated wire 5, the effective resistance does not increase due to the skin effect in a high frequency band of several Mflz.
The main magnetic pole 2 can be excited while suppressing heat generation.

The number of turns of the covered conductor 3 wound around the circumferential surface of the main magnetic pole 2 for this excitation is 13 turns in this embodiment, and the covered conductor 3 is fixed to the main magnetic pole 2 with adhesive. has been done.

The yoke 4 is made of the same low-loss magnetic material as the main pole 2 and functions as a magnetic path, so-called return path. In addition, when the magneto-optical recording medium is brought close to each other, the tapered portion 6
is equally valid. The shape of the yoke 4 is cylindrical,
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. This cutout part 1
The diameter of the yoke 1 is approximately 4 mm, and the length of the yoke 4 in the direction of the axis of rotational symmetry is approximately 5 am. Further, the outer diameter of the yoke 4 is approximately 7 mm, and the inner diameter is approximately 6 mm.

Incidentally, a groove portion 12 for taking out the covered conductor wire 3 is provided at the joint portion of the yoke 4 to the bottom portion 8 of the main magnetic pole 2.

The high-frequency modulated magnetic field generating device 1 of this embodiment has a cross section as shown in FIG. 2.

The high frequency modulated magnetic field generator l of the first embodiment as described above
can be used for a magneto-optical recording medium as shown in FIG.

That is, in FIG. 6, a magneto-optical recording medium 61 has a magneto-optical recording layer 63 formed on a substrate 62 made of a material such as polycarbonate resin, methacrylic resin, glass, etc., and a protective film 64 formed thereon.

The magneto-optical recording layer 63 is, for example, a Tb-Fe-Co film and has a thickness of approximately 1000 mm. Further, the protective film 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 61. The high-frequency modulated magnetic field generator l uses a laser beam to perform the above-mentioned magneto-optical recording [
Laser device 6 for heating 63 to one point or more
5 and are arranged opposite to each other with the magneto-optical recording medium 61 interposed therebetween.

When the input signal is a high-frequency signal, this high-frequency modulated magnetic field generating device 1 has high-frequency characteristics as described below, so it can reverse the output magnetic field according to the signal, and therefore can easily override. It can be carried out.

Experimental Example 1 Experimental results regarding a prototype example of the high frequency modulated magnetic field generating device 1 of this example will be shown. First, in an experiment, a high frequency current of IMllz was applied to the above-described high frequency modulated magnetic field generator 1, and the current waveform and the generated magnetic field waveform were measured.

FIG. 7 is a waveform diagram of the measured current waveform, which is a sine wave with a peak value of 2A (ampere). A current probe and a synchroscope are used to measure this current. Moreover, the waveform shown in FIG. 8 is the generated magnetic field waveform, and shows the magnetic field waveform at a point 0.7 fi away from the main magnetic pole surface. The peak value of this magnetic field waveform is 300
It can be seen that a high frequency magnetic field is generated in accordance with the high frequency current. Note that this measurement is based on a diameter of 3 mm.

The output voltage of a calibrated integrator was measured using a synchroscope using a one-turn pickup coil.

Furthermore, although the energization time during this experiment was approximately 30 minutes, the temperature rise of the high frequency variable 1il magnetic field generator 1 was approximately 20 minutes.
The value is kept below ℃.

Experimental Example 2 A 1:T experiment was also conducted regarding the relationship between the size of the high-frequency modulated magnetic field generator l of the first embodiment, self-inductance, and magnetomotive force. First, in an experiment, three high-frequency modulated magnetic field generators were made using the same material as the high-frequency modulated magnetic field generating bag 'lt, 1 of the first embodiment, each having a core portion of similar shape and different size. The cross-sectional areas of these main magnetic poles are 121-2, 36-2, and 7-2, respectively. Then, the self-inductance coefficient and magnetomotive force were determined for each of these from the relationship of the number of turns. The results are shown in Table 1.

Table 1 (d = distance from the main pole surface! Il) The conclusion from the experimental results shown in Table 1 is that the smaller the area of the main pole, the better the magnetomotive force required to obtain the required magnetic field (2000e). (AT i ampere turns) is small. Therefore, by making the entire high frequency modulated magnetic field generator small, it is possible to efficiently generate a magnetic field.

Comparative Example 1 For comparison, the coated conducting wire 3 consisting of a plurality of insulated wires 5 connected in parallel in the high frequency modulated magnetic field generating device 1 was replaced with a single winding (copper wire), and the wire was energized. The single winding was o, zssm in diameter and had 13 turns. The energization is
A sine wave (maximum current value 2 A) of Iz was used.

As a result, the temperature increased by approximately 100°C or more within 10 minutes. This means that the skin depth of copper in IMIIz is 100μ.
This is because the single winding has an insufficient effective cross-sectional area for the current. Therefore, when the insulated wire 5 is used, the generation of heat can be more reliably suppressed than when a single winding is used.

Second Embodiment In the high frequency modulated magnetic field generating device of the present invention, for example, the tapered portion 6 of the high frequency modulated magnetic field generating device l of the first embodiment may have a different shape.

As shown in the cross-sectional shape of FIG. 3, the high-frequency modulated magnetic field generating device 31 of the second embodiment has no tapered portion, and the tip portion 37 and the circumferential surface 36 of the main magnetic pole 32 are at a right angle. It is formed. The material of the main magnetic pole 32 is N1-2n ferrite, and the winding wound around the main magnetic pole 32 is a coated conductor vA33 consisting of a plurality of insulated wires connected in parallel to each other.
It has become.

A yoke 34 forming a magnetic path is also attached. These dimensions, materials, etc. are the same as those of the high frequency modulated magnetic field generating device 1 of the first embodiment described above.

Although it is possible to form the main pole 22 with no tapered portion at all, the shape of the tapered portion may be optimized based on the spatial intensity distribution of the exciting magnetic field.

Third Embodiment High frequency variation 1 of the third embodiment! The magnetic field generator 41 is a fourth
As shown in the figure, the yoke 4 is removed from the high frequency modulated magnetic field generating device 1 of the first embodiment. The yoke 4 is made of the same low-loss magnetic material as the main pole and functions as a magnetic path, but depending on the distance between the magneto-optical recording medium and the tip of the main pole, the yoke may not be present as described later. Sometimes it works more effectively.

The material of the main magnetic pole 42 and the main magnetic pole 42. The dimensions of the tapered portion 46 and the tip portion 47 and the structure of the covered conductor 43 are the same as those of the high frequency modulated magnetic field generating bag N1 of the first embodiment.

Fourth Embodiment As shown in FIG. 5, a high frequency modulated magnetic field generator 51 according to the fourth embodiment has the yoke 4 removed from the high frequency modulated magnetic field generator ff1l according to the first embodiment, and the tapered portion 6. It has a shape that does not form. That is, as the cross-sectional shape is shown in FIG. 5, there is no yoke, no tapered portion is provided, and the tip portion 57 and the circumferential surface 56 of the main pole 52 are formed at a right angle.

Note that the material of the main magnetic pole 52 and the main magnetic pole 52. The dimensions of the tip 57 and the structure of the covered conductor 53 are the same as those of the high frequency modulated magnetic field generator 1 of the first embodiment.

Comparison of high-frequency modulated magnetic field generators of the first to fourth embodiments High-frequency modulated magnetic field generators of the first to fourth embodiments 1
．． No. 31, No. 31, No. 31, No. 31, No. 31, and No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, and No. 31, No. 31, No. 31, No. 31, No. 31, and No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, and No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, No. 31, and No. 31, No. 31 and No. 31, No. 31 and No. 31. A Gaussmeter was used for measurement.

As a result, a relationship as shown in FIG. 9 is obtained. In Figure 9, the horizontal axis represents the distance from the main magnetic pole surface (dragon), and the vertical axis represents the strength of the magnetic field (Os/A). In Figure 9, ○ indicates the high frequency modulation of the first embodiment. The magnetic field generating device 1, ■ is the high frequency modulated magnetic field generating device 31 of the second embodiment, * is the high frequency modulating magnetic field generating device 41 of the third embodiment, and the opening is the high frequency modulating magnetic field generating device 51 of the fourth embodiment. This is a point that shows the characteristics of each.

From the results shown in Fig. 9, when the distance between the main magnetic pole surface and the magneto-optical recording medium to be magnetized is short, a magnetic field can be generated efficiently by providing a yoke or by providing a tapered part on the main magnetic pole. will be possible.

〔Effect of the invention〕

In the high-frequency modulated magnetic field generating device of the present invention, a coated conducting wire, which is a collection of a plurality of insulated wires connected in parallel, is wound around the main magnetic pole. Therefore, it is possible to prevent the skin effect in which a large amount of current flows to the periphery, thereby suppressing heat generation from the covered conductor, and achieving stable recording and reducing power consumption.

Furthermore, a low-loss magnetic material is used as the material for the main pole.

Therefore, when used in combination with the above-mentioned insulated strand wire, a constant strong magnetic field that reverses in the high frequency band can be efficiently generated, and there is no problem such as heat generation. Therefore, it can be used as a bias coil in the magnetic field modulation method. Useful and fully capable of being overridden in real time.

Further, if necessary, a tapered portion can be provided at the tip of the yoke or main pole that forms the magnetic path, which is particularly effective when magneto-optical recording media are arranged close to each other.

[Brief explanation of drawings]

1 is an exploded perspective view of a high frequency modulated magnetic field generator according to the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is a sectional view of a high frequency modulated magnetic field generator according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view of a high-frequency modulated magnetic field generator according to a third embodiment of the present invention, FIG. 5 is a cross-sectional view of a high-frequency modulated magnetic field generator according to a fourth embodiment of the present invention, and FIG. is a side view for explaining the usage state of the high frequency modulated magnetic field generator of the present invention, FIG. 7 is a current waveform diagram when current is applied to IMllz, FIG. 8 is a magnetic field waveform diagram in that case, and FIG. 9 1A is a characteristic diagram showing the characteristics of the high-frequency modulated magnetic field generator of the first to fourth embodiments, and FIG. 1O is a schematic diagram for explaining the principle of the magnetic field modulation method. 1.31, 41.51...High frequency variation 1! Magnetic field generator 2.32, 42.52... Main magnetic pole 3.33, 43.53... Covered conductor wire 4.34... Yoke 5... Insulated wire 6.46... Taper part Patent Applicant Sony Corporation Agent Patent Attorney Kowa Miwami Tamura Sakae - 1ri Fig. 4 Fig. 5 used &'Asahi/1 example Fig. 6 Fig. 7 Fig. 8 Fig. distance 1ill (mm) Ea world Turning t1 Distance cutting from the turret surface A relation Figure 9 Isokai Mugi Sounoshiki

Claims (1)

[Claims] A high-frequency modulated magnetic field having a main magnetic pole made of a low-loss soft magnetic material with one end facing the magneto-optical recording layer, and a coated conductor made of a plurality of insulated wires connected in parallel to each other is wound around the main magnetic pole. Generator.