JPH03212804A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve the initial magnetic permeability and reproducing sensitivity of the magnetic head by using single crystal ferrite materials having a high recording power in a magnetic gap part and using single crystal ferrites of a small magnetorestriction in the greater part of a magnetic path. CONSTITUTION:The magnetic path near the magnetic gap 3 is constituted as the magnetic path forming surface of the {100} face of the MNZn single crystal ferrites 7b, 8b having a compsn. consisting of 60 to 65mol% Fe2O3, 22 to 24mol% MnO and 10 to 14mol% ZnO. The magnetic path exclusive of the magnetic path nar the magnetic gap 3 is constituted by using the MNZn single crystal ferrites 7a, 8a having a compsn. consisting of 52 to 55mol% Fe2O3, 25 to 35mol% MnO and 16 to 20mol% ZnO in such a manner that the {110} face thereof constitutes the magnetic path forming surface and the butt surfaces of the gap are the {111} face. The recording power is enhanced in this way and the magnetic paths in the state of obviating the degradation in the initial magnetic permeability are obtd. The reproducing efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to magnetic heads, particularly video tape recorders (
The present invention relates to a magnetic head using single-crystal ferrite as a core material for use in VTRs (hereinafter referred to as VTRs).

(Prior Art) It is well known that one of the ways to realize high-density recording in consumer VTRs is to improve the characteristics of magnetic tape by increasing its sensitivity and reducing noise. . Regarding magnetic tapes using highly reliable iron oxide magnetic powder, the coercive force Hc and residual magnetic flux density Br have significantly improved in recent years due to improvements in the magnetic properties of iron oxide magnetic powder and improvements in manufacturing technology. For example, magnetic tapes with greatly improved coercive force He, such as 950 oersteds compared to the conventional 700 oersteds, have come into practical use.

Incidentally, in order to sufficiently magnetize a magnetic tape having a high coercive force Hc as described above, a magnetic head used for recording must have a large saturation magnetic flux density Bs.

As the magnetic head, both a so-called metal head and a ferrite head can be considered, but a ferrite head is used because it has various advantages such as excellent wear resistance, high frequency characteristics, and low cost. As,
When constructing a magnetic head using single-crystal ferrite as a core material, instead of the conventional core material made of single-crystal ferrite with a saturation magnetic flux density Bs of 4800 Gauss, a core material made of single-crystal ferrite with a saturation magnetic flux density Bs of 6000 Gauss is used. It has been considered to obtain and use a magnetic head with improved recording performance using a core material.

FIG. 11 is a perspective view of a conventional magnetic head constructed using single crystal ferrite as the core material.

In the figure, 1.2 is a core made of MnZn single crystal ferrite material, 3 is a magnetic gap, 4 is a winding hole, and 5 and 6 are glass molds for regulating the track width of the magnetic gap. Department.

In the magnetic head shown in FIG. 11, each core half 1, 2
As a core material constituting the core material, Fe2O3 is 52 to 55 mol% and MnO is 25 to 35 mol%.

When using MnZn single crystal ferrite with a composition of 16 to 20 mol% ZnO and a saturation magnetic flux density Bs of 4800 Gauss, the above-mentioned MnZn single crystal ferrite has a thermal expansion coefficient of 110 to 20%. 120×10-'/”
C, and the magnetostriction λ1110 is 11~3X10-'
, λ44, is 4 to 6X10-', and the initial magnetic permeability is 100 at I MHz when the magnetic path plane is (110) for a ring with an outer diameter of 5 mm, an inner diameter of 3 mm, and a thickness of 1.5 mm.
500-1000.10M for 0-2000.5MHz
In Hz, it is 450-700.

In addition, in the magnetic head shown in FIG. 11 described above, Fe2O3
is 60 to 65 mol%, MnO is 22 to 24 mol%,
When using MnZn single crystal ferrite with a composition of 10 to 14 mol% ZnO and a saturation magnetic flux density Bs of 6000 Gauss, the above-mentioned MnZn single crystal ferrite has a thermal expansion coefficient of 130 to 140X10-'/'C, and magnetostriction λ,. .

is -5~-8X 10-', λ1□, is 30~33X1
0-', and the initial permeability is 5 mm in outer diameter and 3 mm in inner diameter.
mm, the magnetic path surface is (100
), IMHz is 1200.5 MHz and 1050.10 MHz is 650.

By the way, the initial magnetic permeability at each frequency of the above-mentioned M n Z n single crystal ferrite with a saturation magnetic flux density Bs of 4800 Gauss, and the M n Z n single crystal ferrite with a saturation magnetic flux density Bs of 6000 Gauss.
The initial magnetic permeability at each frequency of Zn single-crystal ferrite differs depending on the crystal plane of the magnetic path plane, as illustrated in FIG. 12.

And M n with a saturation magnetic flux density Bs of 6000 Gauss
It is clear from Figure 12 that when Zn single crystal ferrite is used as the constituent material of the core half-hole, the magnetic flux efficiency will be better if the magnetic path forming plane is (100), so the saturation magnetic flux density Bs is When MnZn single-crystal ferrite of 6000 Gauss is used as the core material, the recording performance has been improved by making the magnetic path forming plane (100).

(Problem to be Solved by the Invention) Now, in order to sufficiently magnetize a magnetic tape having a high coercive force He, a magnetic head constructed using a single crystal ferrite having a large saturation magnetic flux density Bs as a core material has been developed. When a core material made of single crystal ferrite with a saturation magnetic flux density Bs of 6000 Gauss is used instead of the conventional core material made of single crystal ferrite with a magnetic flux density Bs of 4800 Gauss, recording ability of I MHz in the low frequency band is achieved. However, compared to the case where a core material made of single crystal ferrite with a saturation magnetic flux density Bs of 4800 Gauss is used, the reproduction output characteristics are improved by about 2 dB as illustrated in FIG. Compared to the case where a core material made of Gaussian single crystal ferrite is used, when a core material made of single crystal ferrite with a saturation magnetic flux density Bs of 6000 Gauss is used, the magnetic flux density is 3 dB to 5 dB as illustrated in Fig. 10. descend.

When using a core material made of single-crystal ferrite with a saturation magnetic flux density Bs of 6000 Gauss, the reason why the reproduction output characteristics decrease as described above is because the magnetostriction increases as the content of iron oxide increases. The initial magnetic permeability is reduced during the manufacturing process of the head, and the initial magnetic permeability of the magnetic head is also reduced during sliding contact with the magnetic tape, resulting in a reduction in the reproduction sensitivity of the magnetic head.

(Means for Solving the Problems) The present invention is characterized in that Fe2O3 is 60 to 65 mol% and MnO is 22% by mole.
(100) in MnZn single crystal ferrite with a composition of ~24 mol% and ZnO of 10-14 mol%
A magnetic path near the magnetic gap including the magnetic gap is configured such that the surface is a magnetic path forming surface, and a magnetic path other than the magnetic path near the magnetic gap including the magnetic gap described above is F.
e2O3 is 52-55 mol%, MnO is 25-35
mol%, M having a composition of 16 to 20 mol% ZnO
Using n Z n single crystal ferrite, its (110
) A magnetic path forming surface is provided, and a gap abutting surface is a (111) surface.

(Function) Fe, 03 is 60-65 mol%, MnO is 22-2
M having a composition of 4 mol% and ZnO of 10 to 14 mol%
The (100) plane of the nZn single crystal ferrite is made into a magnetic path forming surface to form a magnetic path near the magnetic gap including the magnetic gap, and the magnetic path near the magnetic gap including the above-mentioned magnetic gap is formed. Other magnetic paths include Fe, 52 to 55 mol% of ○□, 25 to 35 mol% of MnO, and ZnO.
A MnZn single crystal ferrite having a composition of 16 to 20 mol% is used, and its (110) plane is the magnetic path forming plane, and the gap abutting plane is the (111) plane. By configuring the magnetic head with
Single-crystal ferrite material with high recording performance is used in the magnetic gap, resulting in high recording performance, and most of the magnetic path is made of single-crystal ferrite with low magnetostriction, so there is no drop in initial magnetic permeability. The magnetic head has a magnetic path with a constant state and has good reproduction efficiency.

(Example) Hereinafter, specific contents of the magnetic head of the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a magnetic head according to an embodiment of the present invention, FIG. 2(a) is a plan view of the magnetic head shown in FIG. ,
), Figure 3 is a longitudinal cross-sectional side view at the x-X line position in Figure 2.
FIG. 4 to FIG. 7 are perspective views for explaining the outline of the manufacturing process of the magnetic head shown in FIG. 1, and FIG. FIG. 3 is a vertical sectional side view of a magnetic gap portion in a magnetic head according to another embodiment of the present invention.

In FIG. 1 showing an embodiment of the magnetic head of the present invention,
Reference numerals 7 and 8 each indicate a half core, 3 a magnetic gap, 4 a winding hole, and 5 and 6 glass mold parts for controlling the track width of the magnetic gap 3, respectively.

Each of the core halves 7 and 8 described above has two types of M n
It is constructed using Zn single crystal ferrite material. That is, the part 7b with subscripts in the figure,
8b contains 60 to 65 mol% of Fe2O3 and 22% of MnO.
The magnetic gap 3 is formed such that the (100) plane in the MnZn single crystal ferrite having a composition of ~24 mol% and 10 to 14 mol% ZnO and a saturation magnetic flux density of 6000 Gauss is the magnetic path forming surface. It is a part that constitutes a magnetic path near the magnetic gap that contains it, and is also indicated by the subscript a in the figure.
The portions 7a and 8a marked with are Fe2O3 from 52 to
55 mol%, MnO is 25-35 mol%, ZnO is 16-20 mol%, and the saturation magnetic flux density is 480.
In M n Z n single crystal ferrite of 0 Gauss (
This is a part that forms a magnetic path in which the (110) plane is the magnetic path forming surface and the gap abutting surface is the (111) plane.

The detailed structure of the vicinity of the magnetic gap 3 in the magnetic head shown in FIG. 1 is shown in FIG. As clearly shown in FIG. 3, which shows a partially enlarged vertical cross-sectional side view of the x-X line position in FIG. 2(b) and FIG. 2(a), Fs, ○, is 60-65 mol%, M
Mn having a composition of 22 to 24 mol% nO and 10 to 14 mol% ZnO and a saturation magnetic flux density of 6000 Gauss
The portions 7b and 8b, which constitute the magnetic path near the magnetic gap including the magnetic gap 3, are made of Zn single crystal ferrite so that its (100) plane is the magnetic path forming surface. within a predetermined depth Ω and for example 45
It exists only in the part shown as the angle θ, which is preferably less than 7 degrees, and in other parts 7a.
, 8a is Fe, ○.

is 52 to 55 mol%, MnO is 25 to 35 mol% Z
Using MnZn single crystal ferrite with a composition of 16 to 20 mol% n○ and a saturation magnetic flux density of 4800 Gauss, its (110) plane is used as the magnetic path forming surface, and the gap abutting surface constitutes a magnetic path with (111 planes).

Note that the angle θ described above is preferably set within the range of O<θ≦45t'.

As mentioned above, M n Z n having a composition of 60 to 65 mol % of Fe and 03, 22 to 24 mol % of MnO, and 10 to 14 mol % of ZnO and a saturation magnetic flux density of 6000 Gauss.
Single-crystal ferrite has large magnetostriction, but if it is used in a small amount near the magnetic gap 3, it will have a large initial permeability and a large saturation magnetic flux near the magnetic gap 3. Since a magnetic path having a high density can be constructed, a magnetic head that can obtain large recording performance and high reproduction efficiency can be constructed.6 In other words, in the magnetic head shown in the first diagram, Fe2O3 is 60 to 60%.
65 mol%, MnO 22-24 mol%, ZnO 10
A M n Z n single crystal ferrite with a saturation magnetic flux density of 6000 Gauss having a composition of ~14 mol % is found in its (1
00) surface is the magnetic path forming surface to form the magnetic air 11.
Portions 7b and 8 constituting a magnetic path near the magnetic gap including 13
As is clear from FIG. 12, the magnetic flux efficiency of the magnetic air gap 3 is made good by using the parts 7b and 8b.
a is Fe2O, 52 to 55 mol%, M n O is 25
Using MnZn single crystal ferrite having a composition of ~35 mol% and 16 to 20 mol% ZnO and a saturation magnetic flux density of 4800 Gauss, its (110) plane is made a magnetic path forming plane, The gap butting surface is (111
) plane, and the sliding surface with the magnetic tape is a (112) plane.
It has a crystal plane structure in which each crystal axis [1101 draws an arrowhead pattern approaching upward in the direction toward the sliding surface.

In the magnetic head shown in the first diagram, the crystal axes [112] and [110]
] is 55 degrees.

Next, with reference to FIGS. 4 to 7, an outline of the manufacturing process of the magnetic head shown in FIG. 1 will be explained. In Fig. 4, A contains 52 to 55 mol% of Fe2O3 and 25 to 55 mol% of MnO.
It is a block material of MnZn single crystal ferrite having a saturation magnetic flux density of 4800 Gauss and having a composition of 35 mol% and 16 to 20 mol% of ZnO, and B has a composition of 60 to 65 mol% of Fe2O3 and 22-22 mol% of MnO. z24 mol%, Zn
The saturation magnetic flux density is 6 with a composition of 10 to 14 mol% O.
000 Gauss M n Z n single crystal ferrite block material, and the two types of M n Z n with different compositions described above.
Zn single-crystal ferrite blocks A and B are bonded by known bonding means 5, such as glass welding, thermocompression bonding, or other bonding methods, in such a state that the crystal planes and crystal axis orientations are as shown in the figure. By applying the means, an integrated block of material as shown in the fourth figure is formed.

A half-core block material CF as shown in FIGS. 6 and 7 is cut out from the block of material illustrated in FIG. 4 in a predetermined manner as shown by CF in FIG. 5.

In order to manufacture a magnetic head as shown in FIG. 1 using the blocks CF and CF of each core half-closed shown in FIGS. 6 and 7, it is necessary to After cutting grooves corresponding to the wire holes and joining the gap-forming surfaces of the two core halves so that a predetermined magnetic gap size is formed between them, the core material for two individual magnetic heads is made. Then, a glass mold part is formed to regulate the track width of the magnetic gap so that a predetermined track width is obtained in the magnetic gap 3.
The magnetic head may be manufactured in accordance with a well-known manufacturing process for magnetic heads.

Next, in the magnetic head shown in FIG. 8, 7 and 8 are core half holes, 3 is a magnetic gap, and 4 is a winding hole.

Each of the core halves 7 and 8 described above has two types of M n
It is constructed using Zn single crystal ferrite material, and the parts 7b and 8b with subscripts in the figure
contains 60 to 65 mol% of Fe2O, and 22% of MnO.
The magnetic gap 3 is formed such that the (100) plane in the MnZn single crystal ferrite having a composition of ~24 mol% and 10 to 14 mol% ZnO and a saturation magnetic flux density of 6000 Gauss is the magnetic path forming surface. It is a part that constitutes a magnetic path near the magnetic gap that contains it, and is also indicated by the subscript a in the figure.
The portions 7a and 8a marked with have FatO3 of 52~
55 mol%, MnO is 25-35 mol%, ZnO is 16-20 mol%, and the saturation magnetic flux density is 480.
In M n Z n single crystal ferrite of 0 Gauss (
This is a part that forms a magnetic path in which the (110) plane is the magnetic path forming surface and the gap abutting surface is the (111) plane.

The magnetic head shown in FIG. 8 is easier to manufacture than the previously described magnetic head shown in FIG.

(Effects of the Invention) As is clear from the above detailed explanation, the magnetic head of the present invention contains 60 to 65 mol% of Fe2O3 and Mn.
(
100) A magnetic path in the vicinity of the magnetic gap including the magnetic gap is configured such that the surface is a magnetic path forming surface, and as a magnetic path other than the magnetic path in the vicinity of the magnetic gap including the above-mentioned magnetic gap,
Fa, O.

is 52 to 55 mol%, MnO is 25 to 35 mol%,
A MnZn single-crystal ferrite having a composition of 16 to 20 mol% ZnO is used, and its (110) plane is the magnetic path forming plane, and the gap abutting plane is the (111) plane. By configuring the head,
Single-crystal ferrite material with high recording performance is used in the magnetic gap, resulting in high recording performance, and most of the magnetic path is made of single-crystal ferrite with low magnetostriction, so there is no drop in initial magnetic permeability. This makes it possible to create a magnetic head with a good magnetic path and good reproduction efficiency.

According to the present invention, the above-mentioned conventional problems can be satisfactorily solved, and a VTR capable of recording and reproducing color images of good image quality can be easily provided.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic head according to an embodiment of the present invention, (,) in FIG. 2 is a plan view of the magnetic head shown in FIG. 1, and (b) in FIG. Fig. 3 is a longitudinal cross-sectional side view taken along the line X-X in a);
4 to 7 are perspective views for explaining the outline of the manufacturing process of the magnetic head shown in FIG. 1, and FIG. 8 is a partially enlarged longitudinal sectional side view at position m. 9 and 1 are longitudinal cross-sectional side views of the magnetic gap portion in the head.
0 and 12 are characteristic side views for explanation, and FIG. 11 is a perspective view of a conventional magnetic head. 1.2... Core half-hole made of MnZn single crystal ferrite material, 3... Magnetic gap, 4... Winding hole,
5゜6... Glass mold part for regulating the track width of the magnetic gap, 7, 8... Two types of M n Z n
A half-core core constructed using single crystal ferrite material,
A, B... Block material of MnZn single crystal ferrite with two different compositions, CF... Block with half-core core, A80 Fu110 Akika

Claims (1)

[Claims] Fe_2O_3 is 60-65 mol%, MnO is 22-2
M having a composition of 4 mol% and ZnO of 10 to 14 mol%
The {100} plane in the nZn single crystal ferrite is used as a magnetic path forming surface to configure a magnetic path near the magnetic gap including the magnetic gap, and to form a magnetic path other than the magnetic path near the magnetic gap including the magnetic gap described above. As a magnetic path, Fe_2O
_3 is 52 to 55 mol%, MnO is 25 to 35 mol%,
A MnZn single crystal ferrite having a composition of 16 to 20 mol% of ZnO is used, and its {110} plane is the magnetic path forming plane, and the gap abutting plane is the {111} plane. magnetic head made by