JPH0668415A - Magnetic head for vtr - Google Patents

Abstract

PURPOSE:To provide the magnetic head for VTRs which can deal with the miniaturization of the VTRs, long-time recording and making higher image quality of televisions and has good recording and reproducing characteristics in a high-frequency band. CONSTITUTION:This magnetic head for the VTRs is constituted by having a pair of core pieces 11, 12 constituted of the nonmagnetic Mn-Zn single crystal ferrite of the compsn. within the range enclosed by A-B-C-D-E-F connecting the respective points, by molar %, A (25 Fe2O3, 30 MnO, 45 ZnO), B (25 Fe2O3, 40 MnO, 35 ZnO) D (58 Fe2O3, 12 MnO, 30 ZnO) E (58 Fe2O3, 4 MnO, 38 ZnO), F (51 Fe2O3, 4 MnO, 45 ZnO), magnetic metallic films 14 formed on the butt surfaces of at least one magnetic gap 15 of a pair of these core pieces 11, 12 and the magnetic gap 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is particularly suitable for high-quality VTRs such as small-sized, long-time recording VTRs, S-VHSs and Hi8mm VTRs.
The present invention relates to a magnetic head used in TR and further in HDTV.

[0002]

2. Description of the Related Art In recent years, with the downsizing of VTRs, recording for a long time, and large screens and high image quality of televisions, high image quality of home VTRs has been demanded, and high density recording, short wavelength recording, frequency Broadband is being promoted. Corresponding to this, VTR
The tape for use has a coercive force of 1 by using a metal tape in which the particle size of a ferromagnetic metal powder such as Fe is made fine or a tape in which a Co-Ni magnetic material is directly vacuum-deposited on a base film. 000 to 1,500 (Oe) tends to have a high coercive force. For such a high coercive force VTR tape, Mn-Zn having a conventional saturation magnetic flux density of about 5000 G is used.
In a magnetic head using a single crystal ferrite as a core, the problem that the ferrite core causes magnetic saturation and sufficient recording / reproduction cannot be performed becomes remarkable. Also, Mn-Z
The n single crystal ferrite has a sufficient reproduction output in the frequency band of about 5 MHz, but has a large decrease in the reproduction output in the high frequency band of 7 to 8 MHz or more.
Therefore, a magnetic head using a metal magnetic film having good soft magnetic characteristics such as sendust and amorphous and having a saturation magnetic flux density of about 10,000 G has become mainstream. FIG. 8 shows an example of the MIG type magnetic head. In the figure, 10 'denotes a magnetic head, which has a high magnetic permeability Mn-.
Zn single crystal ferrite is used as the core pieces 11 'and 12', and a metal magnetic film 14 'having a high saturation magnetic flux density such as sendust or amorphous is formed on the surfaces facing the magnetic gap by sputtering or the like to form a pair of core pieces 11', 12 'is joined by a non-magnetic film 15' which serves as a magnetic gap, glass 13 'reinforces the joint, and the track width is regulated. FIG. 9 is a view showing a laminated type magnetic head 20 'which has recently been put into practical use. The magnetic head 20 'has a laminated film 24' formed by alternately laminating a metal magnetic film such as sendust or amorphous and a nonmagnetic film such as SiO _{2 on} the side surface of a nonmagnetic substrate 21a 'such as ceramics by sputtering or the like. Formed,
The laminated film and the non-magnetic substrate 21b 'are joined with glass or the like to produce a core half. Next, the laminated film produced in the same manner as this core half body is abutted with the core half body sandwiched by the non-magnetic substrates 22a 'and 22b', joined by the non-magnetic film 25 'which becomes the magnetic gap, and the glass 23' is used. The joint width is reinforced and the track width is regulated.

[0003]

The magnetic Mn- shown in FIG.
MI using a metal magnetic film on a Zn single crystal ferrite core piece
The G type magnetic head is a magnetic head which has good workability of single crystal ferrite and excellent wear characteristics with respect to the tape. However, since single crystal ferrite has a large magnetostriction constant,
There is a drawback that the noise caused by sliding on the VTR tape is large, and the large inductance causes a reduction in reproduction output in a high frequency band and noise is easily generated. Further, the metallic magnetic film and the ferro-core react to generate a pseudo gap at the boundary, which interferes with the magnetic gap and causes undulations in the frequency of the reproduction output, which causes fluctuations in the reproduced image of high quality. Easy to deteriorate. On the other hand, FIG.
The laminated magnetic head sandwiching the laminated film of the core and the metallic magnetic film on the non-magnetic substrate shown in Fig. 3 has a small inductance and a small magnetostriction constant, and it is easy to narrow the track due to its structure, so that high density and short wavelength recording is possible. It is a magnetic head suitable for. However, since the ceramics forming the non-magnetic substrate has a polycrystalline structure, cracks and chippings are easily generated and the material has a problem in workability. In addition, the sliding property with the tape is not so good that uneven wear is caused, a step is formed between the laminated film and the non-magnetic core, and surface roughness due to suspicious attachment with the tape is likely to occur. There are drawbacks.

The inventors of the present invention previously disclosed in Japanese Patent Laid-Open No. 3-12666.
No. 2 discloses a non-magnetic Mn-Zn ferrite for a magnetic head, and Japanese Patent Application Laid-Open No. 3-127315 proposes a composite floating magnetic head in which a slider is formed of a non-magnetic Mn-Zn ferrite. However, the invention disclosed above is mainly composed of CaO, MgO,
It is a non-magnetic Mn-Zn ferrite in which an additive such as ZrO ₂ is indispensable, and it was effective in a polycrystal, but a single crystal of good quality could not be formed and could not be put to practical use. . The inventors of the present invention are able to grow a high-quality non-magnetic Mn-Zn single crystal ferrite by further examining the growth conditions of the single crystal and further limiting the composition range without adding CaO or the like. And Further, by using the non-magnetic Mn-Zn single crystal ferrite for the substrate, the workability is good, the sliding noise is small, the head characteristics in the high frequency band are good, and the magnetic head for a VTR has a long life. Could be provided.

[0005]

The magnetic head of the present invention has a mol% of A (Fe ₂ O ₃ : 25, MnO: 30, ZnO: 4).
5), B (Fe ₂ O ₃ : 25, MnO: 40, ZnO: 35),
C (Fe ₂ O ₃ : 30, MnO: 40, ZnO: 30), D (F
e ₂ O ₃ : 58, MnO: 12, ZnO: 30), E (Fe ₂ O)
_{3: 58, MnO: 4,} ZnO: 38), F (Fe 2 O 3: 5
1, MnO: 4, ZnO: 45) are connected to each other.
Non-magnetic Mn having a composition within the range surrounded by C-D-E-F
A magnetic head for a VTR using -Zn single crystal ferrite. One of them is that a pair of core pieces is made of non-magnetic Mn-Zn.
MI which is composed of single crystal ferrite and has a metal magnetic film formed on the magnetic gap facing surface of at least one of the core pieces.
This is a G-type VTR magnetic head. The metal magnetic film may be formed on only one core piece, or may be formed on both core pieces. The other one is that a substrate is made of non-magnetic Mn-Zn single crystal ferrite, and a pair of core pieces sandwiching a laminated film of a metal magnetic film and a non-magnetic film on the substrate, and abutting surfaces of the core pieces. It is a laminated type VTR magnetic head in which a magnetic gap is formed.

[0006]

The magnetic head for a VTR according to the present invention is a non-magnetic Mn-
Since the core piece is composed of Zn single crystal ferrite and the metal magnetic film is used, the sliding noise is small, the inductance is small, and the noise in the high frequency band is small.
It has good head characteristics. Furthermore, since a metal magnetic film having a high saturation magnetic flux density is used, high density recording can be supported. On the other hand, the non-magnetic Mn-Zn single crystal ferrite is non-magnetic, thermal expansion coefficient (82~98) × 10- ⁷ / ℃
In, except that slightly smaller than the front and rear 110 × 10- ⁷ / ℃ of magnetic ferrite, Vickers - scan hardness 600
The magnetic head has an appropriate hardness of 700 kg / mm ² , little wear due to sliding with the tape, good workability, and a long-life magnetic head can be obtained.

[0007]

【Example】

(Example) in _{mole% (Fe 2 O 3: 45} , MnO: 17,
ZnO: 38) and _{(Fe 2 O 3: 30,} MnO: 35, Z
(nO: 35) was mixed with two materials in a dry mixer and then calcined at 1200 ° C. for 3 hours. Then, it was put into a platinum crucible and grown in an oxygen atmosphere at a temperature of 1650 ° C., and then switched to a nitrogen atmosphere, the crucible was lowered, and gradually cooled from the tip to manufacture a non-magnetic single crystal ferrite. A magnetic head was manufactured using this non-magnetic Mn-Zn single crystal ferrite and the characteristics were compared. (Example 1) in _{mole% (Fe 2 O 3: 45} , MnO: 1
7, ZnO: 38) non-magnetic Mn-Zn single crystal ferrite was used to fabricate the MIG type magnetic head shown in FIG. In FIG. 1, 10 is a magnetic head, 11 and 12 are non-magnetic Mn-Zn single crystal ferrite core pieces, 13 is reinforced glass, and 14 is Fe-A formed by sputtering.
It is a 1-Si based metal magnetic film. Mol% for comparison
And (Fe ₂ O ₃ : 54, MnO: 30, ZnO: 16)
A similar magnetic head was manufactured using the magnetic Mn-Zn single crystal ferrite of No. 1 and the reproduction output characteristics of self-recording and reproducing were compared. The main configuration and conditions of the head are shown below. Metal magnetic film: Fe-Al-Si system Magnetic film thickness: 2 μm Laminated film thickness: 10 μm Track width: 20 μm Gap length: 0.35 μm Gap depth: 25 μm Tape: Metal tape Relative speed: 5 .6 m / sec FIG. 6 is a diagram showing the measurement results. Magnetic Mn of Comparative Example
In the magnetic head using -Zn single crystal ferrite, a waviness phenomenon is observed due to the influence of the pseudo gap and sliding noise, and the reproduction output is remarkably reduced on the high frequency band side. On the other hand, the magnetic head using the non-magnetic Mn-Zn single crystal ferrite of the present invention does not cause a waviness phenomenon, has a small decrease in reproduction output in a high frequency band, and is excellent in magnetic head characteristics.

Example 2 (Fe ₂ O ₃ : 3 in mol%)
0, MnO: 35, ZnO: 35) non-magnetic Mn-Zn
A laminated magnetic head shown in FIG. 2 was manufactured using single crystal ferrite. In FIG. 2, 20 is a magnetic head, and 21
Reference numerals a, 21b, 22a and 22b are non-magnetic substrates, 23 is a reinforcing glass, 24 is a laminated film, and 25 is a magnetic gap. With this laminated head and the mol% used in Example 1, (Fe ₂
O ₃ : 54, MnO: 30, ZnO: 16) magnetic Mn
The C / N frequency characteristics of the MIG type magnetic head in which the core piece was composed of -Zn single crystal ferrite were compared. The main configuration and conditions of the head are shown below. Metal magnetic film: Fe-Al-Si system Laminated film: 5 μm × 4 layers Non-magnetic film: 100 nm Track width: 20 μm Gap length: 0.35 μm Gap depth: 25 μm Tape: Metal tape Relative speed: 5.6 m / Sec The result is shown in FIG. Unused SV not recorded
The sliding noise was compared using an HS tape. MI
In the G type magnetic head, sliding noise with the tape occurs and C
Although / N is decreased, the magnetic head of the present invention hardly generates noise, and the noise reduction effect is particularly large in a high frequency band. Next, the sliding wear characteristics of the magnetic head of the present invention used in Examples 1 and 2 and the magnetic head using MnO—NiO ceramics were compared. It was confirmed that the magnetic head of the present invention was appropriately worn, had no uneven wear with the metal magnetic thin film, and had no surface roughness, and had good sliding characteristics. The parallel MIG type and the laminated type have been described above as an example, but the present invention can be applied to the trapezoidal type shown in FIG. 4 and the inclined type shown in FIG. .

[0009]

The high-quality magnetic head for a VTR of the present invention enables a magnetic head having high image quality with little noise even in a high frequency band and having a long life.

[Brief description of drawings]

FIG. 1 is a perspective view of a magnetic head for a VTR showing an example of the present invention.

FIG. 2 is a perspective view of a magnetic head for a VTR showing an example of the present invention.

FIG. 3 is a diagram showing a composition range of a non-magnetic Mn—Zn single crystal ferrite core of the present invention.

FIG. 4 is a perspective view of a VTR magnetic head according to another embodiment of the present invention.

FIG. 5 is a perspective view of a VTR magnetic head according to another embodiment of the present invention.

FIG. 6 is a diagram showing reproduction output characteristics of self-recording / reproduction of magnetic heads of the present invention and a comparative example.

FIG. 7 is a diagram showing C / N frequency characteristics of magnetic heads of the present invention and a comparative example.

FIG. 8 is a perspective view showing the basic configuration of a conventional VTR magnetic head.

FIG. 9 is a perspective view showing the basic structure of a conventional VTR magnetic head.

[Explanation of symbols]

 10 magnetic head for VTR 11 non-magnetic Mn-Zn single crystal ferrite core piece 12 non-magnetic Mn-Zn single crystal ferrite core piece 13 bonding glass 14 metal magnetic film 15 magnetic gap 20 VTR magnetic head 21 non-magnetic Mn-Zn single crystal Ferrite core piece 22 Non-magnetic Mn-Zn single crystal ferrite core piece 23 Bonding glass 24 Laminated film 25 Magnetic gap

Claims (2)

[Claims] 1. A mol% of A (Fe ₂ O ₃ : 25, MnO: 30, ZnO: 45), B (Fe ₂ O ₃ : 25, MnO: 40, ZnO: 35), C (Fe ₂ O). _{3: 30, MnO: 40,} ZnO: 30), D (Fe 2 O 3: 58, MnO: 12, ZnO: 30), E (Fe 2 O 3: 58, MnO: 4, ZnO: 38), F (Fe ₂ O ₃ : 51, MnO: 4, ZnO: 45) A non-magnetic Mn-Zn single crystal ferrite with a composition within a range surrounded by ABCDECF connecting points. And a magnetic gap formed between the pair of core pieces, a metal magnetic film formed on the magnetic gap facing surface of at least one core piece of the pair of core pieces, and a magnetic gap.
Type magnetic head for VTR. 2. A mol% of A (Fe ₂ O ₃ : 25, MnO: 30, ZnO: 45), B (Fe ₂ O ₃ : 25, MnO: 40, ZnO: 35), C (Fe ₂ O). _{3: 30, MnO: 40,} ZnO: 30), D (Fe 2 O 3: 58, MnO: 12, ZnO: 30), E (Fe 2 O 3: 58, MnO: 4, ZnO: 38), F (Fe ₂ O ₃ : 51, MnO: 4, ZnO: 45) A non-magnetic Mn-Zn single crystal ferrite with a composition within a range surrounded by ABCDECF connecting points. A pair of core pieces composed of a laminated film of a metal magnetic film and a non-magnetic film, and a magnetic gap formed on the abutting surface of the core pieces sandwiched by a substrate composed of A laminated type magnetic head for a VTR.