JPH05314404A - High frequency-modulated magnetic field generator - Google Patents

Abstract

PURPOSE:To prevent a magnetic flux saturation in a core of a high frequency- modulated magnetic field generator and to improve magnetic field characteristics by setting a height of a main pole to a width or less of the pole. CONSTITUTION:A height h1 of a main pole 21 is set to a width r1 or less of the pole 21. Thus, a magnetic flux saturation in a core can be prevented, and power consumption is reduced. When the height of the pole 21 is set equivalently or more to a height of a coil 10, a necessary magnetic field range can be assured with certainty.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency modulation magnetic field generator for applying a modulation magnetic field to a magneto-optical recording medium, and particularly to a high frequency for enabling overwriting of a recording signal in a high frequency region in real time. The present invention relates to a modulation magnetic field generator.

[0002]

2. Description of the Related Art A recording method for performing thermomagnetic recording of information on a magneto-optical recording medium for reading out information bits (magnetic domains) by magneto-optical interaction is, for example, a magnetic thin film formed by a perpendicular magnetization film. The magneto-optical recording medium having the above is subjected to so-called initialization in which the direction of its magnetization is preliminarily aligned in one direction perpendicular to the film surface. Information is recorded as binarized information bits by forming a magnetic domain having perpendicular magnetization in the direction opposite to this magnetization direction by local heating such as laser light irradiation.

In this recording method, prior to the rewriting of information recording, the process of erasing the recorded information (the magnetic field direction is the same as the initialization), that is, the time for erasing is used, and the high transfer rate is used. Can not be recorded in. On the other hand, the time for such an independent erase process is unnecessary,
A recording method using a so-called magnetic field modulation overwrite method has been proposed.

The magnetic field modulation overwrite method will be briefly described with reference to FIG. The magnetic thin film 43 in the magneto-optical recording medium 42 is irradiated with laser light through the lens 41.
The magnetic thin film 43 in the portion of the magneto-optical recording medium 42 to be recorded is heated by the laser device 44 for heating the magnetic thin film. Then, by applying a magnetic field by the high-frequency modulation magnetic field generator 45 that generates a magnetic field modulated according to the input signal, the time for the independent erasing process becomes unnecessary and recording is performed.

FIG. 14 shows a conventional example, for example, the one described in Japanese Patent Laid-Open No. 63-53701. In the high frequency modulation magnetic field generator shown in FIG. 14, one end of the main magnetic pole 47 is a tapered taper portion 48, and a yoke portion 49 is connected to the main magnetic pole 47 to suppress the spread of the generated magnetic field. Reference numeral 50 is
A flange portion of the main magnetic pole 47, reference numeral 51, is a winding wire applied to the main magnetic pole 47.

In the case of Japanese Patent Application Laid-Open No. 63-53701 shown in FIG. 14, since the portion of the main magnetic pole around which the coil is wound is thick, the coil inductance becomes large and the coil inductance becomes 5M.
In a high frequency modulation magnetic field generator that needs to modulate a magnetic field with a high frequency of about Hz, when the coil inductance is large, it becomes difficult for a current to flow in the coil, and the rise of the magnetic field cannot be obtained. For this reason, it can be used continuously. If the main magnetic pole is made thin, the coil inductance will surely decrease, and it is considered that the main magnetic pole can be used as a high-frequency modulated magnetic field generator that needs to modulate the magnetic field at a high frequency of about 5 MHz.

However, when the main magnetic pole is high, the magnetic flux is saturated in the main magnetic pole, so that a considerable amount of power is consumed to obtain the required magnetic field.
It cannot be used.

Further, if the tip end of the main magnetic pole is formed into a sloped surface such as a taper shape, the number of processing steps is increased, and if the structure is such that the yoke portion is divided into two bodies, bonding is required. Become. For this reason, it is necessary to reduce the magnetic resistance of the bonded portion of the yoke portion, and it is necessary to raise the surface accuracy of the bonded portion of the yoke portion to make them adhere to each other. It is not generally adopted because it costs money.

[0009]

As described above, when the main magnetic pole is made thin, the coil inductance surely decreases, and it is used as a high frequency modulation magnetic field generator which needs to modulate the magnetic field at a high frequency of about 5 MHz. It seems possible. However, if the main magnetic pole has a height, the magnetic flux is saturated in the main magnetic pole, so that a phenomenon in which power consumption is considerably required to obtain a required magnetic field occurs, so that the main magnetic pole cannot be used.

Therefore, an object of the present invention is to prevent magnetic flux saturation inside the core in the high frequency modulation magnetic field generator.
Another object is to ensure a necessary magnetic field range in a high frequency modulation magnetic field generator.

[0011]

According to a first aspect of the present invention, there is provided a high frequency modulation magnetic field generating device, which is provided along a diameter direction of a magneto-optical recording medium, and a main magnetic pole for applying a magnetic field to the magneto-optical recording medium. A first coil which is wound around a main magnetic pole and which excites the main magnetic pole at a high frequency by passing a current according to a recording signal.
And a second coil for bias-exciting the main magnetic pole are arranged, and the high-frequency modulated magnetic field generator comprises a back core magnetically coupled to the main magnetic pole. It is characterized in that it is less than the width of the magnetic pole.

According to a second aspect of the present invention, there is provided the high frequency modulation magnetic field generator according to the first aspect, wherein the height of the main magnetic pole is equal to the height of the coil, or the height of the main magnetic pole is the height of the coil. It is characterized by being higher than Sa.

[0013]

[Operation] Flux saturation is likely to occur mainly on the side of the main pole opposite to the magneto-optical recording medium. If, for example, ferrite is used as the material of the high-frequency modulation magnetic field generator, the magnetic field characteristics at high frequencies will be significantly deteriorated (see FIG. 2), and the magnetic field characteristics at high frequencies will also be significantly deteriorated by the heat generated by the coil or the like.

However, from the relationship between the width and height of the main magnetic pole, 1 (width): 1 (height) or less, that is, the height of the main magnetic pole is equal to or less than the width of the main magnetic pole, so that the magnetic flux is saturated at a high frequency. Can be solved. This can be explained from the results of the magnetic field simulation described below.

The result of the magnetic field simulation is shown in FIG.
As shown in Fig. 4, this is the B-H curve of the core material assuming the maximum internal magnetic flux on the vertical axis and the width-height ratio of the main magnetic pole (ratio of the main magnetic poles) on the horizontal axis. 20 measurement points
Match the magnetomotive force so that it becomes 0 Oe (Oersted),
The maximum magnetic flux inside the core was calculated.

When the height of the main magnetic pole, which is the ratio of the main magnetic poles, is increased, the maximum internal magnetic flux increases, but the increase decreases at a certain point. This is a phenomenon that occurs because the core material is saturated with magnetic flux.

When the magnetic flux is saturated inside the core, the efficiency of the generated magnetic field with respect to the magnetomotive force applied to the coil is lowered, and the magnetomotive force for obtaining the same generated magnetic field is increased. At this time, the ratio of the main magnetic poles that the magnetic flux does not saturate inside the core was (width: height) = 1: 1 or less.

The dimensions of the core portion used in the magnetic field simulation are as shown in FIG. 1B, and the main magnetic pole width (r1) is 0.
The value z of the height (h1) was made variable with respect to 5 mm.
The reason why the internal magnetic flux is set to 200 Oe is that the magnetic field required for recording on the magneto-optical recording medium is about 200 Oe.

In the magnetic field simulation,
A part other than the main magnetic pole of the core part of the high frequency modulation magnetic field generator,
In other words, the back core part escapes the magnetic flux of the main pole, dissipates heat,
The width is made equal to or larger than the outer diameter of the coil due to the necessity of supporting the coil. Also,
The height of the back core portion is required to be 0.3 mm or more for the escape of the magnetic flux of the main magnetic pole and the heat radiation. In the simulation, the width of the back core part is 0.5 mm.

[0020]

3 to 8 relate to a first embodiment of the present invention, FIG. 3 is an explanatory view relating to dimensions of a high frequency modulation magnetic field generator, FIG. 4 is an exploded perspective view of a coil portion and a core portion, and FIG. 6 is an assembly and cross-sectional view of the coil portion and the core portion, FIG. 6 is a cross-sectional view showing a part of the coil portion, FIG. 7 is an explanatory diagram relating to measurement of magnetic field simulation, and FIG. 8 is a graph showing results of magnetic field simulation.

As a first embodiment, FIGS. 4 and 5 show the shape of a high frequency modulation magnetic field generator. A main magnetic pole 21 for generating a magnetic field for recording or erasing that faces the magneto-optical recording medium at one end, and a back core 22 magnetically coupled to the main magnetic pole 21 at the other end of the main magnetic pole 21, The magnetic pole 21 and the back core 22 are collectively referred to as a core portion 20. Core part 2
The material of 0 is, for example, Ni-Zn ferrite or M
n-Zn ferrite is used.

The coil portion 10 wound around the main magnetic pole 21 for exciting the main magnetic pole 21 excites the main magnetic pole 21 at a high frequency, and a high frequency exciting coil 11 as a first coil, and biases the main magnetic pole. It is composed of a bias exciting coil 12 as a second coil. The wire used for the high frequency excitation coil 11 has a diameter larger than that of the bias excitation coil 12.

FIG. 4 shows an exploded perspective view of the core portion and the coil portion. The core portion 20 has a shape in which the center of the main magnetic pole 21 is the center of rotation, and the main magnetic pole 21 and the back core 22 are cylindrical. In the coil portion 10, two terminals are output from one coil. This is made by integrally forming a high frequency exciting coil 11 for exciting the main magnetic pole to a high frequency and a bias exciting coil 12 for biasing the main magnetic pole 21. Because it was done. FIG. 6 shows a cross section of the coil portion 10. The frequency exciting coil 11 and the bias exciting coil 12 are arranged in order from the inside.
And are wound alternately. The inner diameter of the coil portion 10 is
Since it varies in manufacturing, if it is manufactured to have the same diameter as the outer diameter of the main magnetic pole 21, it cannot be assembled and the slump is deteriorated. Therefore, the inner diameter of the coil portion 10 is formed larger than the outer diameter of the main magnetic pole 21.

FIG. 5A shows the assembly view of FIG. FIG. 6 shows a cross-sectional shape around the center of rotation of the core portion 20. At this time, the size of each part of the coil part 10 and the core part 20 is 0.3 to 0.6 mm in the width of the main magnetic pole 21. The height of the main magnetic pole 21 is equal to or less than the width of the main magnetic pole 21, and is 0.3 mm or more, which is higher than 10 heights of the coil. The width of the back core 22 is equal to or larger than the outer shape of the coil 10. A magnetic field simulation was performed under the condition that the height of the back core 22 was 0.3 mm or more, and the dimensions of each part at this time are summarized in Table 1.

[0025]

[Table 1] The relationship between the reference numerals and the dimensions is as shown in FIGS. 3A and 3B, where h1 is the height of the main magnetic pole, r1 is the width of the main magnetic pole, h2 is the height of the back core, and r2 is the back core. Is the width of. Also,
h3 is the height of the first and second coils. In addition, this first
In the embodiment, the coil is formed as one body, but in FIG. 3B, it is shown as a separate body.
As shown in Table 1, in the magnetic field simulation, the ratio of the width r1 of the main magnetic pole to the height h1 of the main magnetic pole is 1: 1.

The core portion 2 of the high frequency modulation magnetic field generator
The material of No. 0 was a ferrite most suitable for high frequency excitation among the ferrites. The result of the magnetic field simulation when the magnetomotive force is set to 5 AT is shown in FIG. In the measurement, as shown in FIG. 7, the tip of the main magnetic pole 21 and the center of the cylinder are set to zero, and the distance y from the zero point is used as a parameter in the upward direction of the central axis. The horizontal distance from the central axis is x, and this point is the measurement point. That is,
From the parameters y1, y2, y3, ..., Yn, points at a distance x are measurement points.

In FIG. 8, the horizontal axis represents the distance (x) from the central axis of the cylinder of the main magnetic pole 21, and the vertical axis represents the magnetic field generated from the main magnetic pole 21. The parameter y is the distance from the tip of the main magnetic pole 21, and represents the distance from the main magnetic pole 21 to the recording layer of the magneto-optical recording medium. By the way, it is considered preferable that the distance from the main magnetic pole 21 to the recording layer of the magneto-optical recording medium is about 0.1 mm.

From the results of the magnetic field simulation when the magnetomotive force was set to 5 AT, the fluctuation of the magnetic field due to the change in the distance from the main magnetic pole 21 to the recording layer of the magneto-optical recording medium was small, and the position control of the high frequency modulation magnetic field generator was performed. You can see that it can be rough. The magnetic field in the recording layer of the magneto-optical recording medium may be up to about 410 Oe, and the core portion 2 at this time can be used.
The maximum magnetic flux density within 0 is about 2500 G in the vicinity of the joint between the main magnetic pole 21 and the back core 22, which is extremely small.

The coil inductance is about 2 μH when the number of coil turns is 30 turns. The maximum magnetic flux density of 2500 G at a high frequency of 5 MHz can be considered to be within the allowable value. Further, the coil inductance of the coil at a high frequency of 2 μH has no electrical problem, and the coil can be driven. The required magnetic field range is 0.3 mm or more, but even if the distance to the recording layer of the magneto-optical recording medium is 0.15 mm, the magnetic field range is 0.4 mm.
Can be secured. The coil inductance and magnetic field range could be confirmed by experiments.

The core portion 20 of this embodiment has a main magnetic pole 21,
The back core 22 is also cylindrical, but is not limited to this shape.

By the way, the conventional high frequency modulation magnetic field generator has the following drawbacks. (1) coil inductance, (2) required magnetic field range,
(3) magnetomotive force, (4) magnetic flux saturation, (5) processing and assembly man-hours, (6) small power consumption, (7) heat generation.

Therefore, the following measures were taken. First, considering the reduction in the number of processing and assembling steps, the core part of the high-frequency modulation magnetic field generator has a linear central cross-sectional shape,
And a simple shape is desirable.

The width of the main magnetic pole can be estimated from the required magnetic field range and the coil inductance. The required magnetic field range is preferably dimensioned so that the magnetic field range of the high frequency modulation magnetic field generator and the optical pickup can be easily aligned with the optical spot.
The optical pickup is attached to the mechanical frame so as to be movable in the seek direction, and the high frequency modulation magnetic field generator is attached to the loading mechanism so as to be movable in the seek direction. The mechanical frame to which the optical pickup is attached and the loading mechanism portion to which the high frequency modulation magnetic field generator is attached are fixed by attaching screws. At this time, the mounting error between the optical pickup and the mechanical frame to which the optical pickup is mounted, the mounting error between the high-frequency modulation magnetic field generator and the loading mechanism unit to which the high-frequency modulation magnetic field generator is mounted, the mechanical frame and the loading The error at the three points of the mounting error with the mechanism part should be within 0.3 mm in total, and the required magnetic field range should be 0.3 mm or more.
If the width of the main magnetic pole is not less than 0.6 mm from the coil inductance, the coil inductance of about 5 MHz becomes large and it cannot be used as a high frequency modulation magnetic field generator.

One drawback to obtaining the required magnetic field range is that when the back core is up to the height of the main pole, the magnetic field is high in the vicinity of the main pole surface, but fluctuations in the magnetic field due to changes in the distance from the main pole. growing. Further, unless the height of the main magnetic pole is higher than that of the coil, the required magnetic field range cannot be reliably ensured. Therefore, in order to ensure the required magnetic field range, the height of the main pole needs to be higher than the height of the coil.

In the present embodiment, the height h1 of the main magnetic pole 21 can be made higher than the height h3 of the coil portion 10 to ensure the required magnetic field range.

Further, in this embodiment, the height h of the main magnetic pole 21 is
By setting the width 1 to be less than the width r1, it is possible to prevent magnetic flux saturation at high frequencies.

In the present embodiment, inexpensive ferrite is used as the material, the coil inductance is made small, the magnetic flux saturation inside the core is prevented, and the magnetic field range of the high frequency modulation magnetic field generator and the optical pickup and the optical spot. It is possible to secure a necessary magnetic field range that facilitates alignment, secure the magnetomotive force of the high frequency modulation magnetic field generator, and reduce the number of processing and assembly steps and power consumption. 9 to 12 relate to a second embodiment of the present invention, FIG. 9 is an exploded perspective view of a coil portion and a core portion, FIG. 10 is an assembly view and a sectional view of the coil portion and the core portion, and FIG. 11 is a magnetic field. It is a graph which shows the result of a simulation.

As a second embodiment, FIGS. 9 and 10 show the shape of a high frequency modulation magnetic field generator. The main magnetic pole 21 has one end facing the magneto-optical recording medium and generates a magnetic field for recording or erasing, and the other end of the main magnetic pole 21 includes a back core 22 magnetically coupled to the main magnetic pole 21. Magnetic pole 2
1 and the back core 22 are collectively referred to as a core portion 20.

The coil portion 10A wound around the main magnetic pole 21 for exciting the main magnetic pole 21 is a high frequency exciting coil 11A as a first coil for exciting the main magnetic pole 21 at a high frequency.
And a bias exciting coil 12A as a second coil for bias exciting the main magnetic pole.

FIG. 9 shows an exploded perspective view of the core portion and the coil portion. The core portion 20 has a shape in which the center of the main magnetic pole 21 is the center of rotation, and the main magnetic pole 21 and the back core 22 are cylindrical. The coil portion 10A includes a high frequency excitation coil 11A for exciting the main magnetic pole 21 to a high frequency and a bias excitation coil 12A for main magnetic pole bias excitation. The bias excitation coil 12A is arranged on the outer peripheral side of the high frequency excitation coil 11A. ing.

FIG. 10A shows the assembly view of FIG.
FIG. 10B shows the coil portion 1 centered on the central axis of the core portion 20.
The cross-sectional shape in which 0A is arranged is shown. Coil part 1 at this time
0A and the size of each part of the core part 20 are 0.
3 to 0.6 mm. The height of the main pole 21 is
The width is equal to or less than the width, and is 0.3 mm or more to be higher than the height of the coil 10A.

The width of the back core 22 is equal to or larger than the outer shape of the coil 10A. The magnetic field simulation was performed under the condition that the height of the back core 22 was 0.3 mm or more. The dimensions of each part at this time are summarized in Table 2. The reference numerals in the table are the same as those in FIG. 3, and the measurement points are also the same as in the first embodiment and are as shown in FIG.

[0043]

[Table 2] The material of the core portion 20 of the high frequency modulation magnetic field generation device was ferrite most suitable for high frequency excitation among ferrites. FIG. 11 shows the result of the magnetic field simulation when the magnetomotive force was set to 5 AT assuming that the high frequency excitation coil 11A was excited in the main magnetic pole 21. In FIG. 11, the horizontal axis represents the distance (x) from the center of rotation of the main magnetic pole 21, and the vertical axis represents the magnetic field generated from the main magnetic pole 21. Parameter y is the main pole 21
Represents the distance from the main pole 21 to the recording layer of the magneto-optical recording medium. It is considered preferable that the distance from the main pole 21 to the recording layer of the magneto-optical recording medium is about 0.1 mm.

This high frequency excitation coil 11A is the main magnetic pole 2
Assuming that the magnetomotive force is set to 5 AT, the magnetic field simulation results when the magnetomotive force is set to 5 AT show that the variation of the magnetic field due to the change of the distance from the main magnetic pole 21 to the recording layer of the magneto-optical recording medium is small, and the high frequency modulation magnetic field is generated. It can be seen that the position control of the device may be coarse. The magnetic field in the recording layer of the magneto-optical recording medium may be up to about 410 Oe, and the maximum magnetic flux density in the core portion 20 at this time is about 2700 G near the coupling portion between the main magnetic pole 21 and the back core 22. It has become very small.

The coil inductance is about 2 μH when the number of coil turns is 30 turns. The maximum magnetic flux density of 2700 G at a high frequency of 5 MHz can be considered to be within the allowable value. Further, the coil inductance of the coil at a high frequency of 2 μH has no electrical problem and the coil can be driven. Required magnetic field range is 0.3m
As long as the distance to the recording layer of the magneto-optical recording medium is 0.15 mm, the range of the magnetic field is 0.
5mm can be secured.

The power consumption can be reduced depending on the shape of the high frequency modulation magnetic field generating device, but the power consumption can be reduced depending on the arrangement of the coils. As a coil for exciting the main magnetic pole, a first coil for exciting the main magnetic pole at a high frequency is wound around the main magnetic pole, and a second coil for generating a bias magnetic field is arranged outside the first coil. Therefore, power consumption becomes possible. That is, with the configuration of this embodiment, small power consumption is possible. Other configurations and effects are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 12 shows a first embodiment having a coil 10 in which a high frequency exciting coil for exciting the main magnetic pole to a high frequency and a bias exciting coil for bias exciting the main magnetic pole are integrally formed, and the main magnetic pole 21 to a high frequency. In the second embodiment in which there are a high frequency excitation coil 11A for excitation and a bias excitation coil 12A for bias excitation of the main magnetic pole, and the bias excitation coil 12A is arranged on the outer peripheral side of the high frequency excitation coil 11A, A comparison is shown when a magnetomotive force of 5 AT is applied to the coil.

In FIG. 12, the horizontal axis represents the distance (x) from the central axis of the main magnetic pole 21, the vertical axis represents the magnetic field generated from the main magnetic pole 21, and the parameter is the distance from the tip of the main magnetic pole 21.
The distance from the main pole 21 to the recording layer of the magneto-optical recording medium is shown.

The first embodiment has a coil 10A in which a high-frequency exciting coil for exciting the main magnetic pole to a high frequency and a bias exciting coil for bias-exciting the main magnetic pole are integrally formed. There are a high frequency excitation coil 11A for exciting the main magnetic pole 21 to a high frequency and a bias excitation coil 12A for biasing the main magnetic pole.
In the second embodiment in which the bias exciting coil 12A is arranged on the outer peripheral side of the high frequency exciting coil 11A, the symbol COS is attached.

According to FIG. 12, there are a high-frequency exciting coil 11A for exciting the main magnetic pole 21 to a high frequency and a bias exciting coil for bias-exciting the main magnetic pole, and the bias exciting coil is provided on the outer peripheral side of the high-frequency exciting coil 11A. 12
It can be seen that the arrangement of A is more efficient than the coil 10 in which the high frequency excitation coil for exciting the main magnetic pole to a high frequency and the bias excitation coil for biasing the main magnetic pole are integrally formed. Since the efficiency is high, the power consumption can be reduced.

As can be seen from the above comparison, the magnetic field generated under the same conditions is larger in the second embodiment than in the first embodiment. This is because the coil that is closer to the main magnetic pole 21, which is the center, is more efficient than the coil that is far away.

The core portion 20 of the above embodiment is the main magnetic pole 2
Although both 1 and the back core 22 have a cylindrical shape, they are not limited to this shape.

[0053]

According to the first aspect of the present invention, there are provided a main magnetic pole which is provided along the diameter direction of the magneto-optical recording medium, for applying a magnetic field to the magneto-optical recording medium, and a first coil which excites the main magnetic pole at a high frequency. A second coil that is wound around the main pole and that generates a bias magnetic field is disposed outside the first coil, and includes a back core that is magnetically coupled to the main pole. The height of the main magnetic pole is equal to or less than the width of the coil, or the height of the main magnetic pole is higher than the height of the coil, preventing magnetic flux saturation inside the core and reducing power consumption. There is an effect that you can.

Further, according to claim 2, the height of the main magnetic pole is equal to the height of the coil, or the height of the main magnetic pole is made higher than the height of the coil, so that the required magnetic field range is surely secured. There is an effect that you can.

[Brief description of drawings]

FIG. 1 is a graph for explaining a result of magnetic field simulation.

FIG. 2 is a conceptual diagram of a BH curve.

FIG. 3 is an explanatory diagram related to dimensions of the high frequency modulation magnetic field generator according to the first embodiment.

FIG. 4 is an exploded perspective view of a coil portion and a core portion.

FIG. 5 is an assembly and sectional view of a coil portion and a core portion.

FIG. 6 is a cross-sectional view showing a part of a coil portion.

FIG. 7 is an explanatory diagram related to measurement of magnetic field simulation.

FIG. 8 is a graph showing the results of magnetic field simulation.

FIG. 9 is an exploded perspective view of a coil portion and a core portion according to the second embodiment.

FIG. 10 is an assembly view and a cross-sectional view of a coil part and a core part.

FIG. 11 is a graph showing the results of magnetic field simulation.

FIG. 12 is a graph for comparing and explaining the first embodiment and the second embodiment.

FIG. 13 is an explanatory diagram relating to a magnetic field modulation overwrite method.

FIG. 14 is a perspective view of a conventional high frequency modulation magnetic field generator.

[Explanation of Codes] 10 ... Coil part 11 ... High frequency excitation coil 12 ... Bias excitation coil 20 ... Core part 21 ... Main magnetic pole 22 ... Back core h1, r1 ... Main magnetic pole height, width h2, r2 ... Back core Height, width h3… height of coil

Claims (2)

[Claims] 1. A main magnetic pole, which is provided along the diametrical direction of the magneto-optical recording medium and applies a magnetic field to the magneto-optical recording medium, is wound around the main magnetic pole, and a current corresponding to a recording signal flows. Thus, in the high frequency modulation magnetic field generation device including the first coil for exciting the main magnetic pole at high frequency and the second coil for exciting the main magnetic pole by bias, and including the back core magnetically coupled to the main magnetic pole. A high frequency modulation magnetic field generation device, wherein the height of the main magnetic pole is equal to or less than the width of the main magnetic pole. 2. The high frequency modulation magnetic field generator according to claim 1, wherein the height of the main pole is equal to the height of the coil, or the height of the main pole is higher than the height of the coil.