JPS62157310A - Recording and/or reproducing electromagnetic transducer - Google Patents

Abstract

PURPOSE:To obtain a recording and reproducing electromagnetic transducer with a stable magnetic characteristic, which can be easily produced at a moderate cost by giving the prescribed shape to a high magnetic permeability material layer installed on a magnetic gap part and tilting the boundary between the material layer and a core main body with respect to a magnetic gap. CONSTITUTION:Grooves 5a and 5b which become the deepest in the center of the magnetic gap and the shallowest on the side edge part are installed on the gap part of the core main bodies 1a and 1b. 'Sendust(R)' being a high magnetic permeability material is filled to form 'Sendust(R)' layers 2a and 2b, and a magnetic gap 3 is formed. The boundaries 4a-1 and 4b-1 between the core main bodies 1a and 1b and the 'Sendust(R)' layers 2a and 2b tilt at an angle theta1 with respect to the magnetic gap 3, while the boundaries 4a-2 and 4b-2 tilt at an angle theta2 with respect to the magnetic gap 3. theta1 and theta2 satisfy an equation theta2=180 deg.-theta1. Thus noise is reduced. theta1 is preferably within a range of 4-60 deg., and 15 deg. is the most preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an electromagnetic transducer for recording and/or reproducing, such as a magnetic head.

A conventional magnetic head has a core made of a soft magnetic material with a magnetic gear, and current flowing through a coil wound around the core forms a leakage magnetic field from the magnetic gap. Recording is performed on the medium in accordance with the current flowing through the coil, or reproduction is performed by the reverse method.

In recent years, a Talarad type magnetic head has been proposed in which a layer made of a high magnetic permeability material such as sendust is provided on the magnetic gap forming surface of a ferrite core body to improve magnetic properties.

FIG. 7 shows an example of this, in which an X-shaped layer 12 of high magnetic permeability material (for example, sendust) is formed on a core body 11 made of Mn-Zn ferrite, and a magnetic gap 13 is formed in the center line. . 1 on both sides of the magnetic gear knob 13
9 is reinforcing glass.

In this magnetic head, when polishing the surface of the magnetic gap during the manufacturing process, the sendust layer 12a at the center of the magnetic gap is polished.
It is difficult to make the thickness of the magnetic gear knob 13 accurately constant, which tends to cause variations in magnetic properties.Furthermore, the width of the magnetic gear knob 13 is the track width TW, and the track width tends to change. In addition, if the above-mentioned polishing becomes excessive, the ferrite core body 11 is sometimes exposed on the magnetic gear sop surface, and a magnetic gap is formed between ferrites or between sendust and ferrite, causing distortion in the leakage magnetic field. This results in deterioration of magnetic properties.

The magnetic head of FIG. 8 is provided with a sendust layer 22 on the core body 21 that slopes and intersects the magnetic gap 23.
This is an example in which a space having a right triangular cross section on both sides of the magnetic gap is filled with reinforcing glass 29.

In this magnetic head, the trunk width TW is determined only by the dimension of the inclined cross section (magnetic gap 23) of the sendust layer 22, so the thickness t (number + μ
m) must be accurate, and its control requires extremely high precision. If this thickness is different from t, it is extremely difficult to correct it.

C.8 Purpose of the Invention The present invention solves the problems of the conventional Tararad type recording and/or reproduction electromagnetic transducer as described above,
It is an object of the present invention to provide an electromagnetic transducer for recording and/or reproduction that is easy to manufacture, has low manufacturing costs, and has stable magnetic characteristics.

21. Constitution of the Invention The present invention is characterized in that a high magnetic permeability material layer is provided in the magnetic gap portion of the core body, and on the facing surface of the magnetic recording medium, the high magnetic permeability material layer is provided in the middle portion of the magnetic gap. The boundary between the core body and the high magnetic permeability material layer is inclined with respect to the magnetic gap so that the core body and the high magnetic permeability material layer are thick and thin from the intermediate portion to both edge portions in the width direction of the contact surface. Pertains to electromagnetic transducers for recording and/or reproduction.

E. EXAMPLE An example in which the present invention is applied to a magnetic head will be described below.

Figure 1 is a plan view of the magnetic head, and Figure 2 is a perspective view of the magnetic head.

On the surface facing a magnetic recording medium (not shown) (for example, a magnetic tape or magnetic disk), grooves 5a and 5b are provided in the core bodies Ia and 1b, respectively, so that the depth is deepest on the center line (not shown) and the depth is shallowest at both side edges. , 5b is a high permeability material Fe-3t-A1 alloy (5 to 11% by weight S
i, 3 to 8% by weight A1, balance essentially consisting of Fe, in this example 9.6% by weight Si, 5.4% by weight A
ffi) filled with a sendust layer 2a having a pentagonal cross section,
2b are formed respectively, sendas) Ji2a, 2b
A magnetic gap 3 is formed perpendicularly to the longitudinal direction on the facing surfaces of the two.

The length of the magnetic gap 3, ie, the width of the core bodies 1a and 1b, is the track width TW.

As the material for the core bodies 1a and 1b, a metal oxide (ferrite) is preferable from the viewpoint of output, and Mn-Zn single crystal ferrite is particularly preferable, and Ni-Zn single crystal ferrite or sintered ferrite (μ.) is preferable. is 35100, maximum permeability (μ, ) is 116500, magnetic hysteresis loss (W
h s ) is 28 erg/cffl/cycle, coercive force (He) is 0.0220e, and specific resistance (ρ) is 8.
It has extremely excellent magnetic properties of 1 μΩ-G, and by forming a magnetic gap between layers 2a and 2b made of such a material, a magnetic head exhibiting excellent magnetic properties can be obtained.

As shown in an enlarged view in FIG. 3, the boundaries 4a-1, 4b-1 between the core bodies 1a, 1b and the sendust layers 2a, 2b are inclined at an angle θ1 with respect to the magnetic gap 3, and the core bodies 1a, Boundary 4a between lb and sendust layers 2a and 2b
-2, 4b-2 is inclined at an angle θ2 with respect to the magnetic gap 3.

The relationship between θ and θ2 is θ2=180°−θ1.

Making the boundary inclined with respect to the magnetic gap has the effect of reducing noise due to a pseudo gap (an undesirable leakage magnetic field generated at the boundary between different materials). This undesirable leakage magnetic field output is reduced by
It is expressed by the following formula.

πTWtanθ λ where TW is the track width, λ is the recording wavelength, and θ is the above-mentioned inclination angle.

Therefore, the larger θ1 is, the more the undesirable noise due to the pseudo gap is reduced. If θ1 is less than 4 degrees, the above effect will not be noticeable, and if it exceeds 60 degrees, the adhesive force between the sendust layer and the core body will be insufficient, and the change in the thickness of the sendust layer will be too large, which will adversely affect the magnetic properties. Therefore, it is preferable that θ1 be an angle in the range of 4 to 60". A particularly preferable angle of θ1 is in the range of 10 to 456. In this example, θ1 is set to 15". 15″
This is the most preferable angle of θ1 from the viewpoint of both the adhesive strength between the core body and the sendust layer and the uniformity of the thickness of the sendust layer.

Next, the manufacturing process of the magnetic helad core shown in FIGS. 1 and 2 will be explained.

FIG. 4(a) shows the material of the core bodies 1a and lb.

First, as shown in FIG. 4B, V-shaped grooves 5a and 5b are cut into the surfaces of the core bodies 1a and 1b, reaching one end surface. In this example, the depths of the V grooves 5a and 5b are the core body 1a,
Although it is set to about 1/10 of the total length of 1b, it may be provided until it reaches both end faces, that is, over the entire length.

Next, as shown in FIG. 2C, sendust is sputtered to form sendust layers 2a and 2b having a thickness of 10 μm. This level of layer thickness is preferable from the viewpoints of both adhesion strength and layer thickness uniformity, and therefore provides high magnetic permeability and provides a high output magnetic head.

Next, V? The surfaces are polished to a flat surface as shown in FIG. 4D so that only the sendust layers on 145a and 5b are left and the core bodies 1a and 1b are exposed. Next, the core bodies 1a, 1
A thin film of, for example, 5 iOz for forming a magnetic gear is formed on the surface of one of the parts b to a thickness of 0.3 μm by sputtering or the like.

Next, as shown in FIG. 6(e), a groove 6a for forming a winding hole is formed.
, 6b are deleted. Note that the winding hole can be formed even if only one of the grooves 6a and 6b is provided.

Next, as shown in FIG. 3(f), the core bodies 1a and 1b are bonded together so that the sendust layers 2a and 2b are aligned. This bonding may be accomplished by glass fusion, which is generally employed in the manufacture of magnetic heads.

The core bodies 1a and Ib are cut along the a-a line and the a''-a'' line that contact both ends of the sendust layers 2a and 2b.

Next, the end surfaces where the sendust layers 2a and 2b are exposed are finished by lapping into curved surfaces to obtain the magnetic head shown in FIG. This magnetic head has grooves 6 shown in FIG. 4(e).
A winding hole 6 is formed by a and 6b. In addition, the first
The magnetic gap 3 shown in FIGS. 2 and 2 is formed.

In the cutting process, if the cutting is performed at a position away from the grooves 5a and 5b, a part of the boundary between the sendust layer and the core body becomes parallel to the magnetic gap, and the noise caused by the above-mentioned pseudo gap cannot be eliminated. Such things should be avoided.

The layer thickness t (see FIG. 3) of the sendust layers 2a and 2b is t=-TW tanθ1. On the other hand, in the conventional magnetic head shown in FIG.
The layer thickness t is t=TWsinθ1. Therefore, θ1
When is 60'' or less, the magnetic head based on the present invention is more economical because the sendust layer thickness t is smaller, the material cost is lower, and the surface treatment time for layer formation is shorter.

Furthermore, making the sendust layer thinner has the following advantages in terms of magnetic properties.

(1) When forming Sendus F by sputtering or other vacuum evaporation, the generation of internal stress can be suppressed to a small level, and generation of magnetostriction and decrease in magnetic permeability can be prevented.

(2) By reducing the occurrence of the internal stress mentioned above, a decrease in adhesive strength with the core body is prevented, and as a result, defects such as deprinting can be prevented, and processing such as grinding and polishing becomes easier. .

(3) The altered layer (intermediate N) formed at the boundary with the core body, which is thought to be caused by the internal stress, is thinned (suppressed), so there is less leakage magnetic field in the pseudo gap and less noise.

Note that the magnetic gap 3 may be inclined with respect to the direction perpendicular to the direction of movement of the magnetic recording medium to form a magnetic head for azimuth recording. To do this, cutting is performed by making the cutting directions a-a line and a'-a' line shown in FIG. 4(f) oblique with respect to the direction perpendicular to the bonding surface.

2 times ■ 1 This example is an example in which the present invention is applied to a multi-head.

FIG. 5 is a perspective view of the multi-head, in which the same parts as the single head of the first embodiment are denoted by the same reference numerals.

In this magnetic head, a groove 7 is provided perpendicularly to the magnetic gap 3 so that a winding hole 6 is exposed between the magnetic gaps 3, and two head portions 8a and 8b are formed by the grooves 7.

As shown in FIG. 6, this magnetic head has a core body 1a.
, lb (state of Fig. 4(f)), Sendust N
A groove 7 is cut deep enough to expose the winding hole between the c-c line and the c'-c' line that touch the ends of the sendust layers 2a and 2b. d touching the other end of
The multi-head shown in FIG. 5 is obtained by cutting along the -d line and the d'-d' line, and lapping the end face where the magnetic gap 3 is formed into a curved surface.

Note that the width of the head portions 8a and 8b is 60 μm, and the width of the groove 7 is 4.
It is 0 μm.

The other steps are the same as in the first embodiment.

In the present invention, since the core width and the track width are the same, it is easy to manufacture such a multi-head.

Although this example is a two-head example, it goes without saying that a multi-track head with three or more heads can be manufactured in the same manner.

In both Examples 1 and 2 above, sendust is used as the high magnetic permeability material, but permalloy (Fe-Ni alloy)
etc. can also be used. Furthermore, although the core body is made of ferrite, it may also be made of permalloy, alperm (Fe-A7! alloy), or other soft magnetic alloys.

In addition, a layer of a high magnetic permeability material such as Sendust is exposed on the surface facing the magnetic recording medium, and the core body surface has a wear-resistant surface layer (which may also be a layer of non-magnetic material such as ceramics). can also be formed to improve durability.

As described in detail in Section 1, the present invention has the following effects.

(1) Since a high magnetic permeability material layer is provided in the magnetic gap, the magnetic properties are excellent.

(2) The boundary between the high magnetic permeability material layer and the core body is inclined with respect to the magnetic gap so that the high magnetic permeability material layer is thick at the middle part of the magnetic gap and thinner at both edges in the width direction. This reduces the negative effects of undesired leakage magnetic fields caused by pseudo gaps, and also reduces the thickness of the high permeability material layer, which reduces the internal stress generated when forming the high permeability material. , excellent magnetic properties,
Both material costs and processing costs can be reduced.

[Brief explanation of drawings]

1 to 6 show embodiments of the present invention, in which FIG. 1 is a plan view of a magnetic head, FIG. 2 is a perspective view of a magnetic head, and FIG. 3 is a view similar to that shown in FIG. Partially enlarged view of Figure 4 (a), (b), (c), (d), (e) and C
f) is a perspective view for explaining the manufacturing process of the magnetic head, FIG. 5 is a perspective view of another magnetic head, and FIG. 6 is a perspective view showing one step of manufacturing the magnetic head of FIG. 7 and 8 are plan views of conventional magnetic heads, respectively. In addition, in the reference numerals shown in the drawings, 1 a, 1 b-----core body 2a, 2 b----- Sendust layer (High magnetic permeability material layer) 3-・-・----m-magnetic gap 4a-1, 4a-2, 4b-1, 4b-2・---1-
−・−・・−・Boundary 5a between the sendust layer and the core body,
5b------V groove 6--Winding hole 6a, 6b-------Winding hole forming groove 7-
・ · ・ ・ ・ ・ ・ Mplod 8a, 8b ・ − · · · · · · · · · · · · · · ·
3. θ2−−・・・・Inclination angle t・−・−・・
・・・−・Sendust layer thickness T W −−−−1・・−
−1−−−・Track width. Agent Patent Attorney Hiroshi Aisaka 4 Figure 5 Figure 6 d'c'cd Figure 8 Meeting

Claims (1)

[Claims] 1. A high magnetic permeability material layer is provided in the magnetic gap part of the core body, and on the facing surface of the magnetic recording medium, the high magnetic permeability material layer is thick in the middle part of the magnetic gap, and from this middle part to the A recording and/or reproducing electromagnetic device in which a boundary between the core body and the high magnetic permeability material layer is inclined with respect to the magnetic gap so that the thickness becomes thinner at both edges in the width direction of the opposing surface. conversion device.