JPS5940305A - Magnetizing method of magnetic material - Google Patents

Abstract

PURPOSE:To form magnetic poles with a small space to a ferromagnetic material of high coercive force, by shifting in steps and intermittently a magnetic head device to a magnetic material with each magnetic pole array pitch (p) in a single direction of a magnetic pole pattern and reversing the current polarity for each shift of the magnetic head device by the pitch (p) for magnetization. CONSTITUTION:When the magnetic pole array pitch (p) of a magnetized pattern is set at about 400mum, for example, it is sufficient to set (a) and (g) at about 150mum and 250mum with the depth (d) set at about <=500mum respectively. A magnetic head device 10 is successively shifted in steps in a fixed direction (arrow A) with each magnetic pole array space (p) to a ferromagnetic material 1, and at the same time the direction of magnetizing current is reversed for a magnetic coil 15 for each step shift of the device 10. Then the polarities of magnetic poles energing at arm parts 13 and 14 of magnetic cores are successively reversed, and the magnetic poles of same polarity are formed at the same part of the material 1. For a magnetized pattern recorded to the material 1, the poles N and S are distributed alternately along a fixed direction A with a fixed length (p) defined as the array pitch. Therefore each magnetic pole is magnetized with equal polarity for each intermittent shift of the device 10. In this way, the magnetization is never attenuated but increased for the magnetized magnetic poles. Thus, the efficiency of magnetization is improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for magnetizing a magnetic material to form a magnetic pole on a magnetic material to be magnetized, and particularly relates to a method for magnetizing a magnetic material to form a magnetic pole on a magnetic material to be magnetized. The present invention relates to a method of magnetizing a magnetic body for sufficient magnetic recording with a narrow magnetic pole spacing.

[Background technology and its problems]

For example, as shown in Fig. 1, a magnet in which N and S poles are alternately magnetized at a constant magnetic pole array pitch p is used in a magnetic erasing head of a magnetic recording/reproducing device such as a tape recorder. There are many. Such a magnet is obtained by magnetizing the surface of the ferromagnetic material 1 so that N and S poles are arranged alternately along one direction (direction of arrow A). In order to magnetize and form a pattern, a magnetizer 2 as shown in FIG. 2, for example, is used.

The magnetizer 2 shown in FIG. 2 is constructed by attaching a conducting wire 4 serving as a current path in a meandering manner to a magnetizing yoke 3 having a comb-shaped cross section. Then, the ferromagnetic material 1 before magnetization, which will become the magnetized material, is brought close to the tip of each protrusion 3a of the comb-shaped magnetized yoke 3,
When a current is passed through the conducting wire 4, for example in the direction of arrow B, a magnetic field due to magnetic flux as shown by the arrow in FIG. 3 appears. The strength of this magnetic field becomes stronger as the current increases, and in reality, a strong magnetic field is generated by instantaneously passing a large current, and the ferromagnetic material 1 is magnetized.

However, with the magnetization method using such a magnetizer 2, it is extremely difficult to sufficiently magnetize and record, for example, a ferromagnetic material having a high coercive force of several thousand Oersteds or more with a narrow magnetic pole spacing of less than 1 tom. be.

In other words, as the spacing between the magnetic poles to be magnetized becomes narrower, the spacing between the valleys 3b of the comb-shaped magnetizing yoke 3 becomes narrower, so that the void that does not penetrate the ferromagnetic material 1 as shown by the dashed arrow in FIG. Even if the magnetic flux increases and the current is increased in order to increase the effective magnetic flux, the root portion of each protrusion 3a of the comb-shaped magnetizing yoke 3 is magnetically saturated and the effective magnetic flux cannot be sufficiently increased. Can not. Furthermore, since the conducting wires 4 are disposed in the valleys 3b of the comb-shaped magnetizing yoke 3, if the interval between the valleys 3b becomes narrow, it becomes impossible to dispose thick conductive wires, which prevents a sufficient magnetizing current from flowing. Therefore, a large magnetic field cannot be obtained.

Furthermore, when manufacturing a magnetic erase head by forming a magnetization pattern on a ferromagnetic material, a pattern is created in which the magnetic field strength of multiple magnetic poles arranged overflowing the magnetic tape running direction of the erase head gradually decreases. Although it is desirable to form a magnetic field, it is difficult to magnetize and form such a gradually decreasing magnetic field pattern using the magnetizer 2 described above.

[Purpose of the invention]

In view of the above-mentioned points, the present invention makes it possible to magnetize and form a magnetic pole pattern with a magnetic pole spacing of 1 inch or less on a ferromagnetic material with a high coercive force of several thousand oersteds or more, and further enables the magnetization and formation of a gradually decreasing magnetic field pattern. The purpose of the present invention is to provide a method of magnetizing a magnetic material that enables the magnetization of a magnetic material.

[Summary of the invention]

In other words, the feature of the method for magnetizing a magnetic material according to the present invention is that a pair of magnetic core arms are dipped in one direction on the surface of a magnetic material to be magnetized to create a magnetic pole pattern in which the polarity is alternately reversed. The magnetic head device is sequentially and intermittently step-fed by the magnetic pole arrangement pinch p in the one direction of the magnetic pole pattern toward the magnetic body, and each time the magnetic head device is fed by the pitch p, the magnetic head device is This is to reverse the polarity of the magnetizing current to the head device and magnetize it.

Therefore, it is possible to form magnetic poles at narrow intervals on a ferromagnetic material with high coercive force, and by changing the above-mentioned magnetizing current, it is also possible to easily form a magnetized pattern in which the magnetic field strength changes depending on the position. can.

〔Example〕

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a perspective view showing an example of a magnetic head device for magnetization used in an embodiment of the method for magnetizing a magnetic material according to the present invention, FIG. 5 is a front view of the magnetic head device, and FIG. is an enlarged front view of the main part.

4 to 6, it has a pair of arm portions 13 and 14 that are connected to the magnetic field, and is located at a predetermined position in the magnetic circuit loop consisting of the magnetic core 11 and the magnetic gap 12, for example, the base 11a of the magnetic core 11. A magnetic coil 15 for generating a magnetizing magnetic field is wound around.

The unmagnetized ferromagnetic material 1, which is the magnetized material, is disposed close to the tip side of each magnetic core arm 13, 14, and the contact between the ferromagnetic material 1 and the ferromagnetic material 1 in these magnetic core arms 13, 14 is The opposing portion includes effective magnetization surfaces 13a and 14 parallel to the surface of the ferromagnetic material 10.
a are formed respectively. Here, as shown in FIG. 7, on the surface of the ferromagnetic material 1 facing the magnetic head device 11, N
.

When a magnetic pole pattern in which S poles are arranged alternately is formed, the effective magnetization surface 13a of at least one of the magnetic core arm portions 13 and 14 is in the above-mentioned one direction (direction of arrow A). The sum a+g of the length a of the magnetic gap 12 and the spacing g in the same direction of the magnetic gap 12 is set to be equal to the arrangement pitch p of the magnetic poles (a+g=p). In this embodiment, the effective magnetization surface 14 of the other magnetic core arm 14 is
The length of a in one direction (direction of arrow A) is also assumed to be a,
As will be described later, the structure is such that it is also possible to magnetize a ferromagnetic material made of a rare earth magnetic material (rare earth cobalt magnet material) such as samarium cobalt.

Furthermore, the shape of the vicinity of the tip of each magnetic core arm portion 13, 14 is as follows:
The depth dl of b and 14b, that is, the length d in the direction perpendicular to the surface of the ferromagnetic material 10, is made as short as possible, and the distance between the arms 13 and 14 increases rapidly as the distance from the magnetic gap 12 increases. The magnetic core arm portions 13 and 14 are formed so as to spread out to minimize the above-mentioned invalid magnetic flux (magnetic flux that does not contribute to the magnetization of the magnetic material).In addition, the cross-sectional area of each magnetic core arm portion 13.14 is It is formed so as to become smaller as it approaches the magnetic gap 12, forming a part of a so-called tapered shape. prevents magnetic saturation.

Here, if the magnetic pole arrangement pitch p of the magnetization pattern is about 400 μm, then a should be about 150 μm, g should be about 250 μm, and the depth d should be about 50 μm.
The thickness is preferably 0 μm or less. In addition, the length of each part as g, depending on the required magnetic pole arrangement pitch p,
d may be selected appropriately, and in this case, it is preferable to set d to approximately the same length as a 10 g.

FIG. 7 is a diagram for explaining a magnetization recording process using such a magnetic head device 10.

In FIG. 7, it is assumed that the magnetic head device 10 is not moved to the right in the figure (in the direction of arrow A) before magnetizing the ferromagnetic body 1, which is the body to be magnetized. In this case, it goes without saying that the magnetic head device 10 may be fixed and the ferromagnetic body 1 may be moved to the left in the figure (in the opposite direction to arrow A).

First, the magnetic head device 10 is placed at the position indicated by the solid line in FIG. 7 with respect to the ferromagnetic material 1, and the magnetic coil 15 is
A current is passed in a predetermined direction so that, for example, an N pole appears on the magnetic core arm 13 side and an S pole appears on the arm 14 side. At this time, the direction of the magnetic lines of force is as shown by the solid arrow in FIG.
The portion 1b KN pole facing the effective magnetization surface 14a of No. 4 is formed by magnetization.

Next, move the magnetic head device 10 toward the ferromagnetic material 1 by arrow A.
The magnetic coil 15 is moved by a length equal to the magnetic pole array pitch p in the direction and placed at the position of the imaginary line in FIG. The S pole is on the magnetic core arm 13 side, and the arm 14 is
Make sure that the N poles are exposed on each side. In this case, in the ferromagnetic material 1, the portion 1b that previously faced the effective magnetization surface 14a of the arm portion 14 is now the effective magnetization surface 1 of the arm portion 13.
3a, but since the direction of the current in the magnetic coil 15 is reversed, the magnetic pole appearing on the core arm side is the same S pole, and the portion 1b of the ferromagnetic body 1 is on the N pole side as before. Become magnetized. Further, at this time, in the ferromagnetic body 1, the portion 1C of the magnetic core arm portion 14 facing the effective magnetization surface 14a is magnetized to the south pole side.

Similarly, the magnetic head device 10 is sequentially fed step by step in the fixed direction (arrow A direction) with respect to the ferromagnetic material 1 by the magnetic pole array interval p, and the direction of the magnetizing current of the magnetic coil 150 is changed every time it is fed one step. By reversing, the polarities of the magnetic poles appearing on each of the magnetic core arm portions 13 and 14 are sequentially reversed, so that the same portion of the ferromagnetic body 1 is magnetized with magnetic poles of the same polarity.

The magnetization pattern magnetized and recorded on the ferromagnetic material 1 in this way is one in which N and S poles are arranged alternately along a certain direction A K with a certain length p as an arrangement pinch, and the magnetic pole The arrangement pitch p is 1 of the so-called magnetic recording wavelength λ.
/2 (p-λ/2).

By the way, during such magnetized recording, the magnetic head device 1
In the magnetic field formed between the magnetic core arm parts 13 and 14 of 0, the corner 13C where the surfaces 13a and 13b intersect and the corner 14C where the surfaces 14a and 14b intersect become a kind of singular point, and the magnetic flux is are concentrated, and the ferromagnetic material 1 is
The portion facing C and 14C is particularly strongly magnetized. Further, among the portions of the magnetic core arm portions 13 and 14 that face the ferromagnetic body 1, inclined surfaces 13e are continuous from the effective magnetization surfaces 13a and 14a toward the core body, respectively.

As for 14e, since it is far from the surface of the ferromagnetic material 10, the ferromagnetic material 1 is hardly magnetized by these inclined surfaces 13e and 14e.

In addition, each magnetization effective surface 13a, 14a and each inclined surface 13e.

The respective boundaries 13d and 14d with 14e are preferably curved so that no concentrated magnetic flux is generated in these areas.

Therefore, magnetization is performed using a magnetic head device 10 in which the magnetic core arm portions 13 and 14 are approximately tapered, and the length a of the effective magnetization surfaces 13a and 14a and the depth d of the magnetic gap 12 are respectively formed to be small. Therefore, a concentrated magnetic flux can be obtained near the gap between the tips of the arms 13 and 14, and a large magnetizing current can be taken, without causing magnetic saturation as in the conventional case. A ferromagnetic material with a high coercive force can be sufficiently strongly magnetized to form a magnetization pattern with a magnetic pole spacing (magnetic pole arrangement pitch) of tmm or less. In addition, the effective magnetization surface 13a of each magnetic core arm portion 13, 14
, 14a are both equal in length a, and the sum of the magnetic gap interval g and this length a, a-1-g, is set equal to the magnetic pole arrangement pitch p, so that the magnetic head device 10 is moved relative to the ferromagnetic material 1, which is the material to be magnetized, intermittently (in steps) by the above-mentioned pitch p, and then the polarity of the magnetizing current is reversed and switched. A part that is magnetized with a magnetic polarity (for example, N pole) will be magnetized with the same magnetic polarity (for example, N pole) during the next magnetization.
It is magnetized by For this reason, each of the magnetic poles is sequentially magnetized with the same magnetic polarity each time the intermittent movement is performed, and the magnetization of the already magnetized magnetic poles is not attenuated (in fact, it is strengthened, so that efficient magnetization can be achieved). .

By the way, in rare earth magnetic materials such as samarium cobalt magnetic materials, the hysteresis characteristic due to a weak magnetic field becomes a point-symmetric characteristic curve centered on the origin, similar to that of general ferromagnetic materials, as shown in Figure 8. It is expressed as,
After receiving a strong magnetic field, it exhibits asymmetric hysteresis characteristics with respect to positive and negative magnetic fields, as shown in FIG. 9, for example. Even when magnetizing such a special magnetic material, according to the magnetization method using the magnetic head device having the above-described structure, the polarity that is first magnetized in the unmagnetized portion of the magnetized object can be changed. Since the next magnetization is performed with the same polarity, the 9th
Effective magnetization is possible without the influence of the hysteresis characteristics shown in the figure.

Next, with respect to the ferromagnetic material 1 serving as the magnetized material, a magnetization pattern is created in which the strength of the magnetic field of the magnetic poles arranged in one direction (arrow A direction) changes depending on the position, for example, gradually decreases. When it is desired to magnetize and form a magnet, it is sufficient to change the amount of current flowing while switching inversion every intermittent relative movement (step feed) of the pitch p. However, when magnetizing and forming the above-mentioned gradually decreasing magnetic field pattern, taking into consideration that the previously magnetized part will be magnetized with the same magnetic polarity and strengthened, start from the magnetic pole with the weaker magnetic field. It is more rational to sequentially magnetize toward the stronger magnetic pole, and it is possible to obtain a magnetization pattern in which the magnetic field decays smoothly.

Next, FIG. 10 shows a magnetizing magnetic head device 20 used in another embodiment of the present invention. A magnetic core 21 of this magnetic head device 20 has a pair of arm portions 2 disposed opposite to each other in one direction (direction of arrow A) with a magnetic gap 22 interposed therebetween.
3 and 24, and one magnetic core arm 23 has a ferromagnetic body 10 that becomes a magnetized body, similar to the above-described magnetic core arm 13.
The sum of the length a of the effective magnetizing surface 23a facing parallel to the surface and the distance g of the magnetic gap 22 is formed so that the sum a0g is equal to the magnetic pole arrangement pitch p, while the other magnetic The length of the magnetizing effective surface 24a of the core arm portion 24 is longer than the above-mentioned length a. In addition, the base 2 of the magnetic core 21
A magnetizing magnetic coil 25 is wound around 1a.

Using such a magnetic head 20, the ferromagnetic material 1 can also be magnetized by step-feeding in the direction of the arrow A by pitch p and then switching the magnetizing current.
It is possible to form a magnetization pattern in which N and S poles are alternately arranged at a pitch p in the direction of arrow A, and it is easy to increase the current and increase the magnetization magnetic field strength.
A ferromagnetic material with high coercive force can be sufficiently magnetized with a narrow magnetic pole spacing.

In this case, if the length of the wide effective magnetizing surface 24a of the magnetic core arm 24 is equal to or greater than the above-mentioned magnetic pole array pinch 9, the unmagnetized ferromagnetic material 1 is magnetized for the first time by the effective magnetizing surface 24a. Although there will be a portion that is finally magnetized with a polarity different from that at the time, the effective magnetization surface 24 of the magnetic core arm portion 24
Among a, the strong magnetizing magnetic field appears in the magnetic cap 2.
5, and the magnetizing magnetic field in the remaining part is very weak, so the effective magnetizing surface 24 in the ferromagnetic material
Even if the area is magnetized at point a, the step feeding will eventually result in a narrow effective magnetization surface 23a of the magnetic core arm 23.
A strong (polarity) magnetic pole is formed at .

For this reason, the magnetic head device 20 has the magnetic core arm 2
4 is forward and the arm 23 is backward, in other words, at least the downstream side (or the ferromagnetic material It is necessary to set the length a in the feeding direction of the effective magnetizing surface 23a of the magnetic core arm portion 23 on the side from which the magnetic core arm 23 comes out) so that the above-mentioned a+g=p.

However, if the magnetized material is a rare earth magnetic material such as samarium cobalt, it is necessary to use the above-described magnetic head device 10 in which the length of the effective magnetization surface of both arms is set to a above.

Note that the present invention is not limited to the above-mentioned embodiments; for example, in the above-mentioned embodiments, the ferromagnetic material and the magnetizing magnetic head device are intermittently (stepwise) moved relative to each other, and each movement However, the ferromagnetic material and the magnetizing magnetic head device are continuously moved, and the pulsed current is reversed and switched every time the ferromagnetic material and the magnetizing magnetic head device are moved by pitch p, or A sinusoidal current synchronized with the movement of the magnetic recording wavelength λ (-2p) may be applied.

〔Effect of the invention〕

As is clear from the above explanation, according to the method of magnetizing a magnetic material according to the present invention, even when magnetic materials with high coercive force are magnetized at narrow intervals, they can be efficiently and strongly magnetized, and the magnetizing current By changing the magnetic field, it is possible to form a magnetization pattern in which the strength of the magnetic poles differs partially.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a magnetization pattern of a ferromagnetic material;
FIGS. 2 and 3 are a perspective view and a cross-sectional view for explaining a conventional magnetizer and magnetizing method. 9 to 9 are enlarged front views illustrating an embodiment of the present invention, FIG. 1 is a schematic diagram showing an example of a magnetization method, and FIG.
9 and 9 are graphs showing hysteresis loops. FIG. 10 is a front view schematically showing a magnetizing magnetic head device used in another embodiment of the present invention. 1... Ferromagnetic material 10... Magnetic head device for magnetization 11... Magnetic core 12... Magnetic gap 13.14... Magnetic core arm portion, 13a, 14a... Magnetizing effective surface 15...Magnetic coil for magnetization Patent applicant Mi Koike, patent attorney representing Sony Corporation

Claims (1)

[Claims] Using a magnetic head device having a magnetic core arm that magnetizes a magnetic pole pattern in which the polarity is alternately reversed along one direction on the surface of a magnetic material to be magnetized, this magnetic head device is attached to the magnetic material. On the other hand, the magnetic pole pattern is sequentially and intermittently step fed by the magnetic pole arrangement pitch p in one direction, and every time the magnetic pole pattern is fed by the pitch p, the polarity of the magnetizing current to the magnetic head device is reversed and magnetized. A method of magnetizing a magnetic material characterized by the following.