JPH04325950A - Magnetic head for magneto-optical recording - Google Patents

Abstract

PURPOSE:To improve the recording efficiency of a magnetic head and to improve the intensity of magnetic field generated from a main magnetic pole formed in this magnetic head. CONSTITUTION:A main magnetic pole 31 to impress the magnetic field, yoke parts 32a-32h magnetically coupled to this main magnetic pole and divided the part facing to the magneto-optical recording disk into plural pieces and a coil 33 wound around these yoke parts 32a-32h are provided in counter to the magneto-optical disk. Then, the main magnetic pole 31 and the respective yoke parts 32a-32h are adjacently arranged so as to base the coil 33 in between.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head for magneto-optical recording that applies a modulated magnetic field to a magneto-optical recording medium to enable overwriting of recording signals.

0002

[Prior Art and its Problems] A magnetic field modulation method as shown in FIG. 7 is known as one of the overwrite techniques for simultaneously erasing and recording information on a magneto-optical recording medium such as a magneto-optical disk. . This is magneto-optical disk 1
A constant laser beam irradiated from a semiconductor laser 18 is applied to the perpendicularly magnetized film 14 of No. 6 through a lens 17 through a disk substrate 15.
The temperature of the perpendicularly magnetized film 14 is raised above the Curie point of this magnetized film 14, and the magnetic head 11
Information is recorded by modulating the magnetic field from the magnetic field via a magnetic field modulation circuit 13 in accordance with a recording signal and leaving a magnetic pattern in the magnetized film 14 in accordance with changes in the magnetic field.

When recording information using the magnetic field modulation method described above, the magnetic field required to reverse the magnetization of the perpendicularly magnetized film 14 depends on the film characteristics, but generally a magnetic field of several hundred Oe or more is required. . Moreover, in order to take advantage of the non-contact advantage of magneto-optical recording, the magnetic head 11 must be connected to the magneto-optical disk.
Therefore, the magnetic head 11 is required to have a large magnetomotive force of several tens of ampere turns or more. In addition, in order to achieve high density recording,
It is also necessary to make the rise time of the head-generated magnetic field sufficiently fast.

As a magnetic head for such magnetic field modulation recording, a main pole excitation type magnetic head having a shape as shown in FIG. 8 is generally used because it is necessary to apply a magnetic field perpendicularly to the magneto-optical disk. A coil 23 having a number of turns N for exciting the main magnetic pole is wound around the main magnetic pole 21, and the main magnetic pole 21 has an opposite magneto-optical disk 16 at its end.
A magnetic field is applied to the The base of the main magnetic pole 21 is magnetically coupled to the main magnetic pole 21 and connected to a yoke portion 22 formed to surround the coil 23 .

When an excitation current I that changes according to a recording signal is passed through this coil 23, a magnetic field corresponding to the recording signal is generated from the main magnetic pole 21 facing the magneto-optical disk 16, and the perpendicular magnetization of the magneto-optical disk 16 is generated. The film can be magnetized.

In the main pole excitation type magnetic head shown in FIG. 8, by increasing the number of turns N of the coil 23 and increasing the excitation current I, a magnetic field strength sufficient to reverse the magnetization on the magneto-optical disk 16 can be obtained. Can be done. However, in this case, the loss in the main pole 21 and the yoke part 22 and the loss in the coil 23
As a result, the magnetic head generates heat, causing problems such as deterioration of the characteristics of the magnetic material of the head and thermal destruction of the insulating coating of the coil. Therefore, a magnetic head has been proposed that increases the recording efficiency of the head and increases the amount of magnetic flux generated at the main pole relative to the magnetomotive force NI applied to the head.

[0007] Japanese Unexamined Patent Publication No. 63-53703 discloses FIG.
Magnetic heads as shown in (a) and (b) have been disclosed. In this magnetic head, a yoke portion 22 is formed to surround a main magnetic pole 21 around which a coil 23 is wound, and this yoke portion 22 extends toward the main magnetic pole 21 on the side of the magneto-optical recording medium. The required gap g is formed. In this way, the magnetic resistance of the magnetic circuit surrounding the coil 23 is reduced, and the constant magnetomotive force N exerted by the coil 23 is reduced.
The amount of magnetic flux per I is increased.

In the magnetic head having such a structure, in order to reduce the magnetic resistance of the magnetic circuit, the cross-sectional area of the coil 23 is made small to shorten the length of the path along which the yoke part 22 surrounds the main magnetic pole 21. It is also desirable to increase the thickness of the yoke portion 22. However, the cross-sectional area of the coil 23 needs to be larger than a certain degree, considering the number of turns to obtain the necessary magnetomotive force and the increase in copper loss due to the increase in resistance at high frequencies in the coil. Since the thickness is determined by the overall size of the magnetic head, there is a limit to the improvement in recording efficiency.

Furthermore, Japanese Patent Laid-Open No. 64-66807 discloses a magnetic head as shown in FIGS. 10(a) and 10(b). This magnetic head has a configuration in which the yoke portion 22 is formed into a plurality of elongated rod-like bodies, and a coil 23 is wound around each of the plurality of rod-like bodies so that the magnetic field generated from the tip thereof is concentrated at one point P on the magneto-optical recording medium. has been done.

[0010] According to this structure, the magnetic field can be concentrated at one point on the magneto-optical recording medium from each thin rod-shaped core, so that the convergence efficiency of the recording magnetic field can be improved. In addition, the core diameter of each thin rod-shaped core is made sufficiently small, and since the magnetic field generation from these cores is performed by coils connected in parallel, the inductance of the entire magnetic head can be reduced, and the excitation current can be maintained even at high frequencies. Makes it easy to flush.

However, in a magnetic head having such a structure, due to the arrangement of the yoke portion 22, the magnetic circuit formed around the coil of one thin rod-like core is difficult to form due to the long thin rod-like core and the possibility of core breakage. Since the area is small and the space through which the magnetic flux passes is large, the magnetic resistance becomes large, and the magnetic field that can be generated per yoke core becomes small. This tendency for the magnetic field to decrease is more pronounced as the core is farther away from the main magnetic pole 21. Therefore, many thin rod-shaped cores are required to obtain the required recording magnetic field. Therefore, in order to obtain the required recording magnetic field, there is a problem that the head shape becomes complicated and the size increases, and even in this example, there is a limit to the improvement of recording efficiency.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a magnetic head for magneto-optical recording that increases the recording efficiency of the magnetic head and improves the strength of the magnetic field generated from the main pole. It is said that

[0013]

[Means for Solving the Problems] In order to solve the above problems, the magnetic head for magneto-optical recording of the present invention has a main magnetic pole that faces a magneto-optical recording medium and applies a magnetic field, and a main magnetic pole that is connected to the main magnetic pole at one end. It has a yoke part that is magnetically coupled and whose other end is divided into a plurality of parts and faces the magneto-optical recording medium, and a coil wound around the divided yoke part, and the main magnetic pole and the yoke part are connected to each other. , are arranged close to each other so as to sandwich the coil.

[0014]

[Operation] The yoke part is divided into a plurality of parts, a coil is wound around these yoke parts, and the magnetic flux generated in the yoke part around which the coil is wound is concentrated on the main magnetic pole. In addition, the coil is divided and wound around the yoke to reduce the volume occupied by the coil and bring the main pole and yoke closer together.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. (First example)

1, 2 and 3 show a first embodiment of a magnetic head for magneto-optical recording (hereinafter referred to as a magnetic head) according to the present invention, with FIG. 1 being a perspective view and FIG. 2 being a perspective view. FIG. 2 is a cross-sectional view of the magnetic head in FIG. 1 taken along line II-II.

A cylindrical main pole 31 protrudes from the center of the upper surface of the disc-shaped holding portion 30 . Further, n (in this embodiment, eight) yoke parts 32a to 32h of the same shape radially protrude from the upper surface of the holding part 30 so as to surround the main pole 31. The main pole, yoke portion, and holding portion are made of a material with excellent magnetic properties at high frequencies, such as a soft magnetic material such as ferrite, sendust alloy, and amorphous alloy. That is,
The yoke portions 32a to 32h are formed by dividing the annular region of the cylindrical block of soft magnetic material on the side facing the magneto-optical disk 16 into eight pieces. Further, these yoke portions are magnetically coupled to the main magnetic pole 31 on the side not facing the magneto-optical disk 16 (the holding portion 30 side). An excitation coil 33 is wound around each yoke portion, and the yoke portions 32a to 32h and the main magnetic pole 31 are arranged close to each other so as to sandwich the coil 33 therebetween. Further, each yoke portion 32a to 32h and the main magnetic pole 31 are
The leading end surfaces thereof are formed on the same plane with a predetermined distance from the medium surface of the magneto-optical disk 16.

Here, when an excitation current is passed through each coil 33 in the same direction, the magnetic flux generated at each yoke portion 32a to 32h flows through a magnetic circuit formed around each coil 33,
Magnetic flux from each yoke portion concentrates on the main magnetic pole 31 . At this time, assuming that the cross-sectional area through which the magnetic flux passes through each of the n-divided yoke portions (n = 8 in this embodiment) is equal to or greater than the cross-sectional area through which the magnetic flux of the main magnetic pole 31 passes, the main magnetic pole In order to obtain a magnetic field equivalent to the main pole magnetic field generated by the applied magnetomotive force NI when winding a coil only around 31, each coil should have NI/
It is sufficient to generate a magnetomotive force of n.

That is, since the number of turns and excitation current of each coil 33 can be reduced, the cross-sectional area occupied by each coil 33 is significantly reduced compared to the case where the coil is wound only around the main pole 31, and the main pole It becomes possible to bring the yoke portion and the yoke portion closer to each other. In this case, if the volume occupied by the coil wound around the main pole is small and there is no problem in winding other yoke portion coils, the coil may be wound around the main pole 31.

As a result, the main magnetic pole 31 and the yoke portions 32a~
The magnetic resistance of the magnetic circuit around the coil 33 consisting of the space near the magneto-optical disk 16 decreases because the magnetic path becomes shorter. Therefore, the amount of magnetic flux flowing through the magnetic circuit increases, and the magnetic field at the main magnetic pole 31 also increases. In this way, in the magnetic head of this example, compared to the conventional magnetic head in which the main pole and the yoke part are far apart, the main pole and the yoke part can be brought closer together, so the external shape of the magnetic head can be reduced. The strength of the magnetic field generated by the main pole can be easily increased without increasing it, and recording efficiency can be improved.

Furthermore, in order to drive each coil 33, a recording excitation current may be applied to each coil individually;
As shown in FIG. 3, some or all of the coils may be connected in parallel to flow the recording excitation current. In this way, if the inductance of each coil is L, the inductance of the entire connected coils will ideally be L/n, and the impedance of the magnetic head will be small even with high frequency excitation, reducing the burden on the excitation circuit and reducing the High recording density recording is possible with low power consumption. (Second Embodiment) FIG. 4 shows a second embodiment of the magnetic head according to the present invention.
FIG. 2 is a perspective view showing an embodiment of the invention.

A prismatic main pole 31 protrudes from the center of the upper surface of the rectangular holding portion 30. Moreover, eight rectangular parallelepiped-shaped yoke parts 32a to 32h protrude from the upper surface of the holding part 30 so as to surround the main pole 31. These main magnetic poles 31 and yoke parts 32a to 3
2h can be formed by cutting two parallel grooves in the vertical and horizontal directions of a rectangular parallelepiped block made of a soft magnetic material such as ferrite so as to cross each other. These yoke parts 32a to 32h are the holding part 3
0, it is magnetically coupled to the main magnetic pole 31. Also,
Four yoke parts 32b, 32d close to the main pole 31,
An excitation coil 33 is wound around each of 32f and 32h.

Here, when an excitation current is passed through each coil 33 in the same direction, the magnetic flux generated at each yoke portion is
The magnetic flux from each yoke portion flows through a magnetic circuit formed around the main magnetic pole 31 and concentrates on the main magnetic pole 31. In this embodiment, as in the first embodiment, the number of turns and excitation current of each coil 33 can be reduced, so the cross-sectional area occupied by each coil 33 can be reduced compared to the case where the coil is wound only around the main pole 31. can be significantly reduced. Furthermore, in this embodiment, the coil is wound around the yoke portion closest to the main magnetic pole 31, but in order to further increase recording efficiency, the coil is wound around the main magnetic pole and all eight surrounding yoke portions. It's okay.

This embodiment basically has the same structure as the first embodiment, but the main pole and yoke portion can be easily formed by simply grooving a rectangular parallelepiped magnetic block. is now possible. In this way, by creating a shape suitable for mass production that can be manufactured by simple processing, a magnetic head with high recording efficiency can be easily obtained at low cost. (Third example)

FIG. 5 is a perspective view showing a third embodiment of the magnetic head according to the present invention. In this embodiment, the second
Since the external appearance is the same as that of the embodiment, a detailed explanation will be omitted and structurally different parts will be explained.

In this magnetic head, the yoke portions 32a, 32c, 32e, and 32g shown in the second embodiment, that is, the yoke portions where no coil is wound, are formed of a permanent magnet 51. These permanent magnets 51 are magnetized upward or downward in a direction perpendicular to the magneto-optical disk, and are attached to the other yoke parts 32b, 32d.
, 32f, and 32h, they are magnetically coupled to the main magnetic pole 31. Therefore, as shown in FIG. 6, the magnetic field at the main pole 31 is composed of a high frequency magnetic field HAC corresponding to the recording signal generated at the yoke portions 32b, 32d, 32f, and 32h, and a permanent magnet 5.
The constant magnetic field HDC in the writing direction or the erasing direction generated by No. 1 is superimposed.

That is, a leakage magnetic field from an actuator for driving a condensing lens of an optical pickup that faces a magnetic head via a magneto-optical disk or an actuator for moving a magnetic head is applied to a magneto-optical disk or a magnetic head. However, by adjusting the amount of magnetization of the permanent magnet, it can be canceled out on the magneto-optical disk. Note that instead of this permanent magnet, a yoke portion 32a is used as in the second embodiment.
, 32c, 32e, and 32g, a coil may be wound around each yoke portion, and a constant magnetic field may be applied by passing a direct current. Therefore, by using the magnetic head of this embodiment, even if there is a leakage magnetic field from other devices near the magnetic head, the influence of the leakage magnetic field is eliminated and stable recording is possible.

Although the embodiments of the present invention have been explained above, the present invention is not limited to the above embodiments. For example, various modifications can be made to the position of the yoke around which the coil is wound, the shape of the yoke facing the magneto-optical disk, the method of wiring the coil, etc. Also,
Of course, the present invention can be used not only for magneto-optical disks but also for any device using a magnetic recording medium.

[0029]

[Effects of the Invention] As explained above, in the magnetic head for magneto-optical recording of the present invention, the yoke portion is divided into a plurality of parts, a coil is wound around these yokes, and the magnetic flux generated in the yoke portion is concentrated on the main magnetic pole. I'm letting you do it. Therefore, the strength of the magnetic field generated from the main pole can be improved. In addition, by dividing the coil, the volume occupied by the coil is reduced and the main magnetic pole and yoke are brought closer together, so even if the external size of the magnetic head is small, the magnetic resistance of the magnetic circuit formed around the coil can be reduced. As a result, the magnetic field generated by the main pole per applied magnetomotive force becomes larger, and the recording efficiency of the magnetic head improves. Therefore, by using the magnetic head of the present invention, only a small amount of excitation current is required to flow through the coil, and losses in the magnetic head and the excitation circuit of the head due to an increase in current can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of a magnetic head for magneto-optical recording according to the present invention.

[Fig. 2] II-I of the magnetic head for magneto-optical recording shown in Fig. 1
FIG. 3 is a cross-sectional view taken along line I.

3 is a diagram showing an example of a coil connection diagram of the magneto-optical recording magnetic head shown in FIG. 1; FIG.

FIG. 4 is a perspective view showing a second embodiment of the magnetic head for magneto-optical recording according to the present invention.

FIG. 5 is a perspective view showing a third embodiment of the magneto-optical recording magnetic head according to the present invention.

6 is a diagram showing the magnetic field at the main pole of the magneto-optical recording magnetic head shown in FIG. 5. FIG.

FIG. 7 is a diagram showing the concept of a magneto-optical recording device.

FIG. 8 is a sectional view showing a conventional magnetic head for magneto-optical recording.

FIG. 9(a) is a perspective view showing another conventional magneto-optical recording magnetic head, and FIG. 9(b) is a sectional view thereof.

FIG. 10(a) is a perspective view showing another conventional magnetic head for magneto-optical recording, and FIG. 10(b) is a sectional view thereof.

[Explanation of symbols]

16... Magneto-optical disk (magneto-optical recording medium), 31... Main magnetic pole, 32a to 32h... Yoke portion, 33... Coil.

Claims (2)

[Claims] 1. A main magnetic pole that faces a magneto-optical recording medium and applies a magnetic field, and a main magnetic pole that is magnetically coupled to the main magnetic pole at one end,
The other end has a yoke part that is divided into a plurality of parts and faces the magneto-optical recording medium, and a coil wound around the divided yoke part, and the main magnetic pole and the yoke part sandwich the coil. What is claimed is: 1. A magnetic head for magneto-optical recording, characterized in that the magnetic head is disposed in close proximity to the magneto-optical recording head. 2. A plurality of yoke portions formed by dividing a surface of a magnetic material having a flat surface facing the magneto-optical recording medium; 1. A magnetic head for magneto-optical recording, comprising: a coil wound around the yoke portion and through which an excitation current can flow so as to apply a magnetic field to a recording medium.