JPH0253213A - Joined ferrite magnetic head - Google Patents

Abstract

PURPOSE:To make a recording characteristic and reproducing characteristic compatible and to obtain excellent electromagnetic conversion characteristics by constituting the front gap part and back gap part of head core half bodies of single crystal ferrites and interposing a polycrystalline ferrite between the single crystal ferrites. CONSTITUTION:The front gap part FG and back gap part BG of both the head core half bodies (I), (II) are constituted of the single crystal ferrite parts 1-4. The polycrystalline ferrite parts 5, 6 are respectively interposed and laminated between the single crystal ferrite parts 1-4 by which a closed magnetic path is constituted. The recording characteristic and the reproducing characteristic are made compatible in this way and the good electromagnetic conversion characteristics are attained. The single crystal ferrite is used in the back gap part BG to lower the ratio at which the polycrystalline ferrite occupies and, therefore, the coercive force in a magnetic circuit part is lowered and the magnetization of the head is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bonded ferrite magnetic head formed by bonding a single crystal ferrite and a polycrystalline ferrite.

[Summary of the invention]

The present invention provides a magnetic head in which a pair of head core halves are butted against each other at the front gap and back gap, using single crystal ferrite in the front gap and back gap of the head core halves, and between these single crystal ferrite By interposing polycrystalline ferrite, magnetization of the magnetic head is prevented and a magnetic head with excellent IIT magnetic conversion characteristics is realized.

[Conventional technology]

In recent years, with the demand for smaller size and longer recording times for devices such as video tape recorders (VTRs) and the emergence of so-called digital video tape recorders, higher density recording and shorter wavelength recording have been promoted. Correspondingly, high coercivity magnetic recording media are being used.

Therefore, it is difficult to achieve both recording and reproduction characteristics with the single ferrite head that has been widely used in the past. For example, a single crystal ferrite with a high saturation magnetic flux density is used in the front gap that contacts the magnetic recording medium, and a high permeability is used in the back gap. A so-called junction ferrite type magnetic head using polycrystalline ferrite having magnetic properties has been proposed.

This bonded ferrite magnetic head was proposed from the viewpoint that magnetic heads must have high saturation magnetic flux density during recording and high magnetic permeability during playback, and are designed to achieve both recording and playback characteristics. It is something that According to this, although it has a simple structure similar to a single ferrite head, high-density recording is possible, and it is even better! It has magnetic conversion properties.

The wire is easily magnetized (which may lower the S/N ratio,
Tape noise and distortion of the playback output signal increase. especially,
When the above-mentioned bonded ferrite magnetic head is used in a VTR, a mesh-like striped pattern (moiré) of various sizes appears on the playback screen, which may significantly deteriorate the image quality.

Therefore, the present invention has been proposed in view of the conventional situation, and it suppresses magnetization of the magnetic head, thereby improving the S/N ratio, preventing the occurrence of tape noise and distortion of the reproduced output signal, The object is to provide a magnetic head with excellent electromagnetic conversion characteristics.

[Problems to be Solved by the Invention] By the way, in the above-mentioned junction ferrite magnetic head,
Most of the material that makes up the magnetic circuit, except for the front gap, has high magnetic permeability.

That is, it is composed of polycrystalline ferrite, and this polycrystalline ferrite has a large coercive force of, for example, 0.10 e (Oersted) or more. In order to achieve the above object, the head is a magnetic head in which a pair of head core halves are butted against each other at a front gap portion and a back gap portion, in which the front gap portion and the back gap portion of the head core halves are made of single crystal ferrite. In addition, polycrystalline ferrite is interposed between these single-crystal ferrites to form a closed magnetic path.

[Effect]

Since the front gap portion of the head core half is made of single crystal ferrite, a high saturation magnetic flux density can be obtained during recording. In addition, since polycrystalline ferrite is interposed between the front gap and the back gap, the average magnetic permeability of the head is high (and a high reproduction output can be obtained during reproduction. Therefore, it is possible to achieve both recording and reproduction characteristics. , extremely good electromagnetic conversion characteristics are achieved.

Furthermore, since single-crystal ferrite is used in the back gap section and the proportion occupied by polycrystal ferrite is suppressed, the coercive force in the magnetic circuit section can be kept low, thereby suppressing magnetization of the head.

〔Example〕

Hereinafter, a specific embodiment of the present invention will be described with reference to the drawings.

A bonded ferrite magnetic head to which the present invention is applied has a pair of head core halves (one
), (n) are abutted against each other at the front gap portion FC and the back gap portion BG and are joined and integrated, and a closed magnetic circuit is formed by these head core halves (1) and (n).

In each of the head core halves (1) and (If), the front gap part FG and the back gap part BG are single crystal ferrite parts (1), (2) # and (3),
(4), these single crystal ferrite parts (1)
, (2), (3), and (4), polycrystalline ferrite parts (5) and (6) are interposed between them, respectively, to form a stacked structure.

The single crystal ferrite part of the front gap part FC (
1) and (3) are both made of single-crystal ferrite having a high saturation magnetic flux density, and form a magnetic recording medium sliding contact surface (7) that comes into sliding contact with the magnetic recording medium, and also constitute a magnetic gap g. Therefore, since the magnetic gap g has a high saturation magnetic flux density, the entire magnetic head exhibits a saturation value equivalent to a head made of a high saturation magnetic flux density material, and is capable of recording sufficient data even on high coercive magnetic recording media. is realized.

In addition, as the above-mentioned single crystal ferrite, for example, F eg
os52. Omo1%, MnO2B, Omo1%.

Examples include those having a composition of 20% ZnO and 1% Omo.

Further, the length Ll of the single crystal ferrite parts (1) and (3) in the depth direction is preferably made to match the depth length of the magnetic gap g. ) is more preferably kept to 100 μm or less in order to prevent tape noise from occurring.

In addition, in the vicinity of the magnetic gear g on the abutting surfaces of the magnetic core halves (1) and (II), there are track width regulating grooves (8) and (8) for regulating the track width, respectively.
) and (9), (9) are cut out.

And these abutted track width regulating grooves (8)
, (9) and (8), and (9) are filled with non-magnetic materials (10) and (11) made of high melting point glass or the like to ensure contact characteristics against the magnetic recording medium.

On the other hand, the polycrystalline ferrite parts (5) and (6) are
It is made of polycrystalline ferrite having high magnetic permeability, and as a result, the average magnetic permeability of the head increases during reproduction, resulting in high reproduction output. The single crystal ferrite parts (5) and (6) have winding grooves (12) and (1) for winding coils (not shown), respectively.
3) are formed respectively.

In addition, as the above-mentioned polycrystalline ferrite, for example, Fexo
, 52.0 mo1%, Mn0 2B, Omo1%Z
Examples include compositions of nO20 and Omo1%. Further, the length of the polycrystalline ferrite parts (5) and (6) in the depth direction is at least the length of the winding grooves (12) and (13) from the zero depth position of the previous magnetic gap g.
It may be any length as long as it reaches the back gap portion BG, which is the end.

A major feature of the present invention is that the same single crystal ferrite as the single crystal ferrite used for the front gap part FG, that is, the single crystal ferrite having a high saturation magnetic flux density, is used for the back gap part BG.

In other words, in the case of a magnetic head in which the portion other than the front gap portion FC is made of polycrystalline ferrite, the coercive force in the polycrystalline ferrite portion becomes large and the quality is magnetized, whereas in this embodiment, By forming crystalline ferrite only in the winding grooves (12) and (13), the proportion occupied by the polycrystalline ferrite is suppressed.
The coercive force in the magnetic circuit portion can be kept low, thereby suppressing magnetization of the head.

Therefore, the signal-to-noise ratio is improved, and there is no generation of tape noise or distortion of the reproduced output signal, resulting in a magnetic head with excellent electromagnetic conversion characteristics.Also, when this magnetic head is used in a video tape recorder, etc. , the risk of moiré appearing on the playback screen is eliminated, and a significant improvement in playback image quality can be expected.

As a result of experiments, the amount of moiré was -30 dB in the conventional cemented ferrite magnetic head, but it became -35 dB in the cemented ferrite magnetic head of this embodiment, further improving the reproduced image quality.

Here, in order to manufacture the magnetic head of this example, first,
As shown in Figure 3, a single crystal ferrite block (14
) and a polycrystalline ferrite block (15), and after mirror-finishing their joint surfaces, a single-crystalline ferrite block (14) and a polycrystalline ferrite block (15) are cut out.
They are alternately laminated in this order to form a bonded body. Then, a bonded ferrite block (16) as shown in FIG. 4 is formed.

Then, the bonded ferrite block (16) is processed with winding grooves, track width regulating grooves, etc., and the magnetic head of this embodiment is completed by going through the steps of manufacturing a normal magnetic head.

In addition, as another method for manufacturing the above-mentioned magnetic head, for example, as shown in FIG.
8), and after mirror-finishing their joint surfaces, the single-crystal ferrite block (17) and polycrystalline ferrite block (18) are joined together to form a single-crystal ferrite block (17) and a polycrystalline ferrite block (18). 18) Produce a pair of ferrite blocks (19).

And these joined ferrite blocks (19)
After mirror-finishing the polycrystalline ferrite block (18) and single-crystal ferrite block (17) surfaces, the polycrystalline ferrite block (18) and single-crystal ferrite block (17) are sequentially bonded so that they face each other. The ferrite blocks (19) thus obtained are joined together to form a joined ferrite block (16) shown in FIG. 4. Thereafter, the magnetic head of this embodiment is completed through the steps described above.

As described above, in the bonded ferrite magnetic head of this embodiment, the magnetic core halves made only of ferrite are formed by bonding them together. However, in the present invention, a high saturation magnetic flux density exists at the abutting surfaces of the magnetic core halves. Moreover, it may be applied to a so-called metal-in-gap type magnetic head in which a ferromagnetic metal material with excellent soft magnetic properties is interposed. According to this, better electromagnetic conversion characteristics can be obtained, and Sufficient recording and reproduction can be performed even on high coercive force magnetic recording media.

〔Effect of the invention〕

As is clear from the above description, the bonded ferrite magnetic head of the present invention has a bonded structure of single crystal ferrite having a high saturation magnetic flux density during recording and polycrystalline ferrite having high magnetic permeability during playback. Moreover, the ratio of polycrystalline ferrite is suppressed by using single-crystal ferrite, so it is possible to achieve both recording and reproduction characteristics, and to keep the coercive force in the magnetic circuit section low. This makes it possible to suppress magnetization of the head.

Therefore, it is possible to improve the signal-to-noise ratio, eliminate the occurrence of tape noise and distortion of the playback output signal, and thereby achieve an excellent t
m conversion characteristics are obtained. Therefore, sufficient recording and reproduction can be performed even on a high coercive force magnetic recording medium.

Furthermore, if the above-described bonded ferrite magnetic head is used in a video tape recorder or the like, occurrence of moiré and the like can be suppressed, and a significant improvement in reproduced image quality can be expected.

5.6...Polycrystalline ferrite part FG...Front gap section BG...Back gap part

[Brief explanation of the drawing]

FIG. 1 is an external perspective view showing an example of a magnetic head to which the present invention is applied, and FIG. 2 is a sectional view taken along line A--A in FIG. 1. 3 and 4 are perspective views showing the manufacturing method of the magnetic head according to the present invention in the order of steps, and FIG. The figure shows the joining process of these blocks. FIG. 5 is a perspective view showing a manufacturing method of a magnetic head according to still another example, and shows the manufacturing process of a ferrite block consisting of a pair of a single-crystal ferrite block and a polycrystalline ferrite block. Patent applicant Sony Corporation agent Patent attorney Akira Koike (and two others) 1, n...
・Head core half body 1.2.3.4 ... Single crystal ferrite part Z

Claims (1)

[Scope of Claims] A magnetic head in which a pair of head core halves are butted against each other at a front gap portion and a back gap portion, wherein the front gap portion and the back gap portion of the head core halves are made of single crystal ferrite, and A bonded ferrite magnetic head characterized in that polycrystalline ferrite is interposed between these single-crystal ferrites to form a closed magnetic path.