JPH04102202A - Magnetic field generator for magneto-optical recording - Google Patents

Abstract

PURPOSE:To suppress temperature rise in the neighborhood of a main pole by forming at least part of the main pole with a metallic material with high heat conductivity, and connecting a radiating member to the metallic material part. CONSTITUTION:A main pole cover 4 consisting of the metallic material with high heat conductivity is provided at a main pole 1 main body, or the whole main pole 1 is formed with the metallic material with high heat conductivity. The extension part 4a of the metallic material is connected to a radiating fin 3a in terms of heat, and developmental heat in the neighborhood of the main pole 1 is radiated in the air via the radiating fin 3a. Also, the radiating fin 3a is provided in and in the neighborhood of a magnetic field generator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic field generator for magneto-optical recording for applying a modulated magnetic field to a magneto-optical recording medium.

[Conventional technology]

Various types of magnetic field ordering devices for magneto-optical recording have been proposed so far. Among them, there is a magnetic field generating device for magneto-optical recording which uses a rewritable magneto-optical disk as a magneto-optical recording medium. When recording information on a magneto-optical disk, this is done as shown in FIG. This method is
This is a magnetic field modulation method that allows so-called overwriting, in which the perpendicular magnetization film 31a of the magneto-optical disk 31 is irradiated with laser light from the optical pink-up 32 to raise the temperature of the perpendicular magnetization film 31a above the Curie point. Leave it behind.
Information is recorded by modulating the magnetic field from the magnetic field generator 33 with a recording signal from the magnetic field modulation circuit 34 and leaving a magnetic pattern corresponding to the pattern of magnetic field changes on the perpendicularly magnetized film 31a.

In such a magnetic field modulation method, there are the following configurations for applying a magnetic field to a magneto-optical disk. First of all,
Control so that the magnetic field generator is located at a distant position (e.g., at a distance of 0.1 to 1.0 mm) so that it does not come into contact with movement in the direction of the magneto-optical disk or rotation of the magneto-optical disk. There is a configuration in which a magnetic field is applied to the magneto-optical disk in a state where the magnetic field is Next, the magnetic field generating device, which is urged in the direction of the magneto-optical disk by a plate blade or the like, is opposed to the magneto-optical disk coated with a lubricating protective film, and the entire magnetic field generating device is moved by the flowing air pressure generated by the rotation of the magneto-optical disk. There is a configuration in which when the magneto-optical disk is levitated, a magnetic field is applied to the magneto-optical disk with the distance between the magnetic field generating device and the magneto-optical disk being approximately 5 to 101 JflI by adjusting the biasing force and the floating blade.

In the former configuration, since the magnetic field generating device is located at a position optically separated from the magneto-optical disk surface, it is possible to prevent the two from coming into contact with each other, thereby improving the durability of both. On the other hand, this configuration requires a large magnetomotive force from the magnetic field generator. For example, a magnetic field 150e (
Ørsted) In order to generate more than 10 AT
(Ampere Tan) or more is required.

In the latter configuration, since the magnetic field generating device is sufficiently close to the magneto-optical disk, the magnetomotive force can be small, but there is a risk that the two may come into contact with each other, which poses a problem in the durability of both.

By the way, among the conventional examples, Japanese Unexamined Patent Publication No. 1-152002 discloses that a magnetic shield is attached to the outer periphery of the core tip of an electromagnetic coil for magneto-optical recording. However, this magnetic shield is intended to reduce the size of the core exposed portion to increase recording density and recording capacity, and is not configured to release heat generated in the core.

Further, Japanese Patent Application Laid-Open No. 63-53701 discloses that one end of the main pole of a high-frequency modulated magnetic field generator is tapered to improve the characteristics of magnetic field generation.

If the shape of the main magnetic pole is formed in this way, an elongated magnetic field can be obtained without supplying more current than necessary, so heat generation etc. can be suppressed. When applied to a device configured to be disposed at a certain position, a certain amount of heat will be generated. However, this conventional example does not disclose a configuration for dissipating the generated heat.

[Problem to be solved by the invention]

Among the conventional techniques described above, a case in which the magnetic field generating device is disposed at a position sufficiently distant from the magneto-optical recording medium will be further described. In order to perform high-density recording on a magneto-optical recording medium with this configuration, a magnetomotive force of several tens of AT or more must be applied to increase the excitation frequency to IMHz or more. Then, heat is generated mainly in the main magnetic pole due to core loss and coil loss in the main magnetic pole where magnetic flux is concentrated, causing a temperature rise of 30° or more.

When such a temperature rise occurs around the main pole, the recording magnetic field decreases due to the decrease in magnetization of the main pole part, the insulation film of the winding deteriorates thermally, and the main pole approaches the magneto-optical recording medium. This causes the temperature of the magneto-optical recording medium to rise,
Problems such as changes in the recorded magnetization pattern and variations in the reproduction output occur.

The present invention is proposed to solve the above-mentioned problems.
In a configuration in which the magnetic field generator is located sufficiently far from the magneto-optical recording medium, the temperature rise of the main magnetic pole is suppressed,
The object of the present invention is to provide a magnetic field generation device for magneto-optical recording that can perform high-density recording on a magneto-optical recording medium.

[Means and effects for solving the problem] In order to achieve the above object, the present invention has a main magnetic pole whose one end faces the magneto-optical recording medium, and an excitation device that is wound around the outer circumference of the cough main magnetic pole to excite the main magnetic pole. A magnetic field generating device for magneto-optical recording having a winding, in which at least a part of the main pole is formed of a metal material with high thermal conductivity, and a heat dissipation member is connected to this metal material part. It is.

In this way, since the radiation fins are connected to the metal material part,
The heat generated around the main magnetic pole can be released into the air from the metal material portion via the heat radiating member, making it possible to suppress the temperature rise in the vicinity of the main magnetic pole.

〔Example〕 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining the present invention in detail. A main pole cover 4 made of a metal material with high thermal conductivity is provided on the main pole body 1a, or, although not shown, the main pole 1
The entire structure is made of a metal material with high thermal conductivity. Then, the extending portion 4a of the metal material is thermally connected to the radiation fin 3a,
The main heat generated in the vicinity of the main magnetic pole 1 is released into the air via the radiation fins 3a. In addition, the radiation fin 3a
are provided in and around the magnetic field generator.

FIG. 2A shows a first embodiment of the present invention, and is an overall perspective view, and FIG. 2B is a longitudinal sectional view.

A large-diameter cylindrical body core 2 with a small-diameter cylindrical main pole body 1a protruding from the center of the upper surface is placed and fixed on a rectangular trapezoidal heat sink 3 made of a metal material with high thermal conductivity. .

The upper end portion of the main pole body 1a is a portion facing the magneto-optical recording medium, and the body core 2 is a portion that magnetically couples the main pole body 1a and the magneto-optical recording medium. The main pole body 1a and the body core 2 are made of Mn-Zn polycrystalline ferrite material.

A cylindrical main pole cover 4 is provided on the outer periphery of the main pole body 1a so as to be in close contact with the main pole body 1a except for the vicinity of the upper end. This main pole cover 4 has leg-shaped extension portions 4 extending along the surface of the body core 2 and further along the upper surface of the heat sink 3.
It has a. The main pole cover 4 is made of a metal material with high thermal conductivity, and forms the main pole 1 of the magnetic field generator together with the main pole body 1a.

An excitation winding 5 is wound around the outer periphery of the main pole cover 4. When a magnetic field-modulated high-frequency recording signal is sent to the excitation winding 5, a magnetic field corresponding to the recording signal in the perpendicular direction is generated from the main pole 1 to the magneto-optical recording medium. Magnetic field modulation recording will be performed.

The main pole cover 4 and the heat sink 3 need to be made of a material with high thermal conductivity. Therefore, aluminum (~230W/m・"C) and copper (~400W/m
・It is possible to use materials such as "C), but since these are non-magnetic materials, if they are used for the main pole cover 4, the magnetic coupling between the excitation winding 5 and the main pole body 1a will be poor, This may lead to a decrease in recording efficiency.Therefore, at least the main pole body 1a should be made of an amorphous alloy, sendust alloy, permalloy alloy, etc., which are metallic magnetic materials with good thermal conductivity and workability (and excellent magnetic properties). It's better to be there.

Since this embodiment is configured as described above, the heat generated centering on the main pole 1 is transferred to the main pole cover 4 and the extension portion 4a.
From there, heat is efficiently transferred to the heat sink 3 and the heat is radiated. For example, in order to perform high-density recording on a magneto-optical recording medium, I
When a magnetomotive force of 30 AT or more is applied to the excitation winding 5 at a high frequency of MH2 or more, the main pole body 1a and the body core 2
The excitation winding 5 generates heat due to iron loss, and the excitation winding 5 generates heat due to copper loss. In particular, near the main pole 1 where magnetic flux is concentrated, a large amount of heat is generated, resulting in a temperature rise of 30° C. or more on the surface of the main pole body 18. In this case, the thermal conductivity of the main pole cover 4 is equal to that of the main pole body 1.
Thermal conductivity of the polycrystalline ferrite material forming a (4 to 6 W
/m・°C) sufficiently large value 50 to 300H
/m・°C, the heat generated in the main pole body 1a is transmitted through the main pole cover 4 and the extension portion 4a, and is further efficiently radiated into the air from the heat sink 3, which has high thermal conductivity. I will continue to do so.

In this way, this magnetic field generating device can keep the temperature rise of the main magnetic pole piece 20"C lower than the ambient temperature even during high-density recording. Therefore, the operating environment temperature of the magneto-optical recording device can be lowered by 20"C. Even if the temperature is about 60''C, the magnetic field generated by the main pole will not be reduced due to the reduction in magnetization near the Curie point (120 to 200°C) of the ferrite material. Furthermore, a temperature rise in the magneto-optical recording medium adjacent to the main pole 1 does not cause a decrease or fluctuation in the reproduction output due to a change in the recorded magnetization pattern. Furthermore, the insulating resin used to cover the excitation winding 5 has a heat resistant temperature (1
There is no thermal change in the vicinity of 20 to 200°C.

Note that a large air flow is generated around the heat sink 3 due to the rotation of the magneto-optical recording medium, so if the heat sink area of the heat sink 3 is made wide, cooling of the vicinity of the main magnetic pole 1 can be made more efficient. This means that it can be implemented.

FIG. 3 is a sectional view according to a second embodiment of the invention. The same reference numerals are given to parts corresponding to those in the first embodiment. In this embodiment, a recess for arranging the main magnetic pole 1 and the excitation winding 5 is formed in the center of the plane of the body core 3 which is placed and fixed on the heat sink 3, and the main magnetic pole is placed in the center of the recess. The magnetic pole l is fixed so that its bottom is in contact with the heat sink 3 and its lower outer periphery is in close contact with the body core 2. Further, an excitation winding 5 is wound around the upper outer periphery of the main pole 1 .

The main pole 1 is entirely made of a metallic magnetic material with high thermal conductivity, and the body core 2 is made of a ferrite polycrystalline material. The bottom portions where these are joined to the heat sink 3 are surface-polished so that they come into close contact with the heat sink 3. In this embodiment, since the main magnetic pole l has a simpler shape than in the first embodiment,
It has the advantage of good workability and a wide selection range of magnetic materials.

With this structure, the heat generated in the main magnetic pole 1 is directly transmitted to the heat sink 3 and radiated into the air. The entire structure may be made of a magnetic metal material such as an amorphous alloy or sendust alloy with high thermal conductivity, but these materials are more difficult to process than ferrite materials and are disadvantageous in terms of material cost.Therefore, this embodiment The main magnetic pole 1 is made of a metal magnetic material lot material (0.2~0.5
It is advantageous in terms of workability and cost to form the body core 2 from a ferrite polycrystalline material.

FIG. 4 is a longitudinal sectional view according to a third embodiment of the present invention.

In this embodiment, the main pole main body 1a and the body core 2 are integrally formed and mounted and fixed on a heat sink 3, as in the first embodiment. A recessed portion for arranging the excitation winding 5 similar to that of the second embodiment is formed around the main pole body 1a.

Further, on the outer periphery of the main pole body 1a made of ferrite material,
A cylindrical main pole cover 4 made of a highly thermally conductive metal material is provided in close contact with the main pole cover 4, leaving only the upper end. This main pole cover 4 is the excitation winding! 5, the surface of the body core 2, and the heat sink 3.
It has a leg-shaped extension part 4a extending along the upper surface of. The main pole cover 4 is made of a metal material with high thermal conductivity, and forms the main pole l of the magnetic field generator together with the main pole body 1a.

An excitation winding 5 is wound around the outer periphery of the main pole cover 4. Furthermore, the excitation drive circuit 6 of the magnetic field generator is provided on the opposite side of the heat sink 3 to the side where the main magnetic pole 1 etc. are provided, and the heat sink 3 is designed to also serve as a stand for the excitation drive circuit 60 board. ing. A shield case 7 is provided outside the excitation drive circuit 6 and fixed to the heat sink 3.

Since the present embodiment is configured in this way, the heat sink 3 and the shield case 7 each have a large heat radiation area, and the heat generated from the magnetic field generator and the excitation drive circuit 6 can be efficiently released into the air. becomes. Furthermore, since the magnetic field generator and the excitation drive circuit 6 are installed very close to each other, even when high-frequency excitation is used for high-density recording, loss in the excitation current transmission line can be reduced, and electromagnetic noise can be reduced. can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, part or all of the main pole is made of a highly thermally conductive metal material, and is connected to a heat sink provided in a magnetic field generator or the like so that heat can be transferred.
Heat generated due to core loss and winding loss occurring around the main pole can be efficiently radiated into the air.

Therefore, it is possible to prevent the main pole generated magnetic field from decreasing due to a decrease in the magnetization of the main pole magnetic body due to a temperature rise around the main pole.

Further, it is possible to prevent a decrease or fluctuation in the reproduction output due to a change in the recorded magnetization pattern. Further, thermal changes in the insulating resin of the excitation winding can be prevented. In this way, it has become possible to appropriately perform high-density recording on a magneto-optical recording medium.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view for explaining the present invention in detail; FIGS. 2A and B are perspective views showing the first embodiment of the present invention;
3 is a vertical sectional view showing the second embodiment of the present invention, FIG. 4 is a longitudinal sectional view showing the third embodiment of the present invention, and FIG. 5 is a longitudinal sectional view showing the conventional FIG. 2 is a diagram explaining the principle of a magnetic field modulation method. 1... Main magnetic pole 3... Heat sink 4... Main magnetic pole cover 5... Excitation winding

Claims (1)

[Claims] 1. In a magnetic recording magnetic field generator having a main magnetic pole with one end facing the magneto-optical recording medium, and an excitation winding wound around the outer periphery of the main magnetic pole to excite the main magnetic pole, the main magnetic pole 1. A magnetic field generating device for magneto-optical recording, characterized in that at least a portion of the magnetic field generator is made of a metal material having high thermal conductivity, and a heat dissipation member is connected to the metal material portion.