JP2612566B2 - Magnetic head for magneto-optical recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magneto-optical recording device, and particularly to a magnetic head thereof.

"Prior art and its problems" As is well known, a magneto-optical recording apparatus uses a laser beam to heat a magnetic recording medium to lower the coercive force, and in this state, performs recording with a magnetic head, thereby achieving perpendicular magnetic recording with a small magnetic flux. This enables magnetic recording. FIG. 3 is a schematic diagram showing the conventional example. The magnetic recording medium 11 has a perpendicular magnetic film 13 on a light-transmitting substrate 12, and the perpendicular magnetic film 13 is covered with a protective film 14. The laser beam L condensed by the condensing lens 15 is irradiated on the perpendicular magnetization film 13, and the irradiated part is heated. The magnetic head 16 performs perpendicular magnetic recording on the heated perpendicular magnetization film 13, and various types are known.In the present invention, a coil 18 is provided around a rod-shaped magnetic core 17. It is intended for rolled types. In the magnetic head 16, a magnetic flux generated by flowing a recording current through the coil 18 reaches the perpendicular magnetization film 13 from the tip of the magnetic core 17, and the magnetization film 13 is perpendicularly magnetized to perform magnetic recording.

The magneto-optical recording device based on the above-described principle, the intensity of the recording magnetic field due to the magnetic flux emitted from the tip of the magnetic core
Is theoretically preferred to be the strongest. However, since the magnetic recording medium 11 is generally formed from a soft material, it is necessary to provide a distance between the magnetic recording medium 11 and the magnetic head 16 in order to prevent the magnetic recording medium 11 from contacting the magnetic head 16 due to surface deflection. Since the end face on the side of the magnetic recording medium 11 is conventionally flat, the recording magnetic field decreases as the distance from the end face of the magnetic core 17 increases. For this reason, the fact that the advantage of the magneto-optical recording device, which allows recording with a small magnetic field, has not been fully exploited has been a reality.

"Object of the Invention" Based on the discovery of such a problem, the present invention sets the point at which the recording magnetic field due to the magnetic flux generated from the rod-shaped vapor core end face becomes strongest at a position away from the magnetic core end face. It is an object of the present invention to obtain a magnetic head for a magneto-optical recording device that can be used.

"Summary of the Invention" The present invention has been made by various studies on the shape of a rod-shaped magnetic core,
Focusing on the principle that the magnetic field generated from a curved surface concentrates at the focal point of the curved surface, and that the intensity of the recording magnetic field generated from a magnetic core having a curved concave end surface is maximized at a position away from the end surface. It was done.
That is, the present invention relates to a magnetic head for a magneto-optical recording apparatus having a magnetic head formed by winding a coil around a rod-shaped magnetic core made of a magnetic material, wherein the end face of the magnetic core on the magnetic recording medium side is not curved. The curved concave surface is provided with a slit or a non-magnetic portion for reducing the surface area of the curved concave surface.

The distance from the end face of the magnetic core to the maximum intensity of the recording magnetic field depends on the diameter of the magnetic core, the curvature of the curved concave surface, and the like. Therefore, if these factors are determined in consideration of the set clearance between the magnetic core and the magnetic recording medium, it is possible to generate a recording magnetic field having the maximum intensity in the perpendicular magnetization film portion of the magnetic recording medium.

Further, by providing a slit or a non-magnetic portion on the curved concave surface, the strength can be reduced for the demagnetizing field and the efficiency can be improved. This effect can be obtained by appropriately setting the area ratio of these slits or non-magnetic portions to the magnetic portions, which appears on the surface of the curved concave surface, regardless of the depth of the slits or non-magnetic portions. Therefore, the non-magnetic portion may be formed by, for example, forming a rod-shaped magnetic core into a laminated structure of a magnetic material and a non-magnetic material. Further, a thin rod-shaped magnetic material may be bundled, and some of them may be connected to each other with a spacer made of a non-magnetic material interposed therebetween to form an end face of the rod-shaped magnetic core with a curved concave surface.

"Examples of the Invention" The present invention will be described below with reference to illustrated examples. FIG. 1 shows an example of the shape of a magnetic head for a magneto-optical recording device according to the present invention, together with a comparative example. First, FIG.
This is a comparative example in which a curved concave surface 21 is formed on the end surface of the rod-shaped magnetic core 20 at the center of the magnetic head 16 on the magnetic recording medium 11 side. The curved concave surface 21 can be formed, for example, from a part of a spherical surface. Since the magnetic field generated from the curved concave surface 21 is concentrated at the focal point of the curved surface, by setting the shape of the curved concave surface 21, the strength of the magnetic field due to the magnetic flux coming out of the curved concave surface 21 is set at a position away from the curved concave surface 21, that is, It can be maximized in the perpendicular magnetization film 13 of the magnetic recording medium 11. The strength of the recording magnetic field depends on the recording current flowing through the coil 18 and the diameter of the curved concave surface 21, that is, the diameter of the magnetic core 20, as described above.

However, if the diameter of the magnetic core 20 is too large, the demagnetizing field increases, and it becomes difficult to generate a magnetic flux in the axial direction of the magnetic core 20. The first solution to this problem is
It is an example of a figure (B), (C), and (D). FIG. 1B shows an embodiment in which a slit 22 is formed in a curved concave surface 21. The slit 22 is effective for reducing the demagnetizing field, although the rate of decrease in the surface area of the curved concave surface 21 is small. Since this effect is not affected by the depth of the slit 22, the function of the slit 22 can be given by the through groove. The curved concave surface 21 may be filled with a non-magnetic material.

Next, the embodiment of FIG. 3C is an embodiment in which the magnetic core 20 has a laminated structure of a magnetic material 23 and a non-magnetic material 24. Further, FIG. 3D shows an embodiment in which a thin rod-shaped magnetic body 26 is bundled, and a spacer 27 made of a non-magnetic material is filled between the magnetic bodies 26 to form the magnetic core 20. In each embodiment,
A curved concave surface 21 is provided on the end surface of the magnetic core 20 on the side of the magnetic recording medium 11.
Are formed.

Next, effects of the present invention will be described based on experimental results. FIG. 2 shows a magnetic core 20 having the dimensions shown in FIG. 1A as a comparative example of FIG. 1A, an embodiment of the present invention of FIG. 1B, and FIG. In the comparative example in which the tip of the magnetic core 20 is sharpened, the distance (spacing) 1 from the end face of the magnetic core 20, the recording magnetic field and the strength Hy
It is the result of having investigated. In the type of FIGS. 1A and 1B, the spacing 1 means the distance from the peripheral edge of the curved concave surface of the magnetic core.

From this graph, it can be seen that in the comparative example ((E) type) in which the tip of the magnetic core 20 is sharp, the recording magnetic field monotonously decreases as the spacing l increases, whereas in the type (B) according to the present invention, the magnetic field decreases. It is understood that the strongest recording magnetic field is generated at a specific position away from the end face of the core 20, and that the change in the recording magnetic field with respect to 1 is small. Further, in the magnetic core of the comparative example (A) in which the tip is simply a curved concave surface, the strongest recording magnetic field is obtained when the spacing 1 is around 300 μm, and the spacing 1 is 100
A recording magnetic field of 10,000 e or more is obtained in the range of up to 600 μm, but when the spacing 1 is 200 μm or less, the recording magnetic field sharply decreases. On the other hand, the type (B) according to the present invention in which the slit is formed in the curved concave surface is about 200 to 600
The recording magnetic field intensity at the spacing of μm is lower than that of the comparative example (A), but the change of the recording density due to the change of the spacing is small.
Stronger recording magnetic field. Given the variation in spacing,
It can be seen that the type (B) according to the present invention is excellent.
Therefore, the position where a strong recording magnetic field is generated and the position of the magnetic recording medium 11
If the position of the perpendicular magnetization film 13 is matched, magnetic recording can be performed more efficiently. FIG. 1 (A),
In the type (B), the recording magnetic field is maximum near the spacing 1 of about 350 μm, which means that the magnetic field generated by the curved concave surface 21 is located at the focal point of the curved surface (the center of curvature of the curved concave surface). It shows that you concentrate.

[Effects of the Invention] As described above, according to the present invention, in a magneto-optical recording device, a recording magnetic field having the maximum intensity can be generated at a position separated by a certain distance from the end face of a magnetic head. Therefore, in this type of magneto-optical recording apparatus in which the magnetic head and the recording medium must be set apart from each other, recording can be performed with less power, efficiency can be improved, and the strength of the demagnetizing field can be reduced. Efficiency can be improved.

In addition, a stable recording operation can be performed for a magneto-optical recording apparatus in which the spacing fluctuation due to surface deflection is severe.

[Brief description of the drawings]

FIG. 1 is a perspective view showing examples (B), (C) and (D) of the magnetic head according to the present invention together with comparative examples (A) and (E), and FIG. 2 is a view showing FIGS. Graphs showing changes in the strength of the recording magnetic field of the magnetic heads of types B) and (E);
FIG. 3 is a sectional view showing the concept of a magneto-optical device recording device. 11 ... magnetic recording medium, 12 ... substrate, 13 ... perpendicular magnetization film,
14 ... Protective film, 15 ... Condenser lens, 16 ... Magnetic head,
20 ... magnetic core, 18 ... coil, 21 ... curved concave surface, 23 ...
... magnetic material, 24 ... non-magnetic material, 26 ... magnetic material, 27 ... spacer.

Claims (1)

(57) [Claims] An apparatus for irradiating a magnetic recording medium with a laser beam to heat the magnetic recording medium, and performing magnetic recording on the magnetic recording medium with the magnetic head under heating, wherein the magnetic head is a rod-shaped magnetic material made of a magnetic material. In a magnetic head for a magneto-optical recording device configured by winding a coil around a core, a magnetic recording medium side end surface of the magnetic core is formed as a curved concave surface, and a slit is formed in the curved concave surface to reduce a surface area of the curved concave surface. Alternatively, a magnetic head for a magneto-optical recording device, comprising a non-magnetic portion.