JPH05234022A - Magnetic head - Google Patents

Abstract

PURPOSE:To provide the MIG head having high recording characteristics even in a long wavelength region for a high-coercive force medium by constituting magnetic alloy films having high saturation magnetic flux densities to adequate film thicknesses and transmitting sufficient magnetic fluxes to a gap surface at the time of recording. CONSTITUTION:Magnetic core half bodies consisting of soft magnetic ferrite which has the saturation magnetic flux density Bsf and has the surface parallel with a magnetic gap and an alloy magnetic material which has the saturation magnetic flux density Bsm and is deposited thereon are butted against each other via a gap material. The side wall film thicknesses a1, a2 and side wall taper angles theta1, theta2 of the magnetic alloy films on at least the succeeding side of tape traveling and the magnetic alloy film thickness b on the parallel surfaces of the gap and the length c in the track width direction on the parallel surfaces of the gap are limited to >=0.6alpha of the track width Tw.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in a VTR or the like and having particularly excellent recording characteristics.

[0002]

2. Description of the Related Art In a magnetic recording / reproducing apparatus such as a VTR,
High coercive force media have come to be used to improve recording density. With respect to this high coercive force medium, magnetic saturation of the head core material becomes a problem, and so-called metal in-gap heads (hereinafter referred to as MIG heads) in which a magnetic alloy material having a high saturation magnetic flux density is arranged in the vicinity of the head gap have been proposed. This type of MIG head is disclosed in JP-A-62-145.
As described in Japanese Unexamined Patent Application Publication No. 510 and JP-A-2-254608, a pseudo gap is formed at the interface between a ferrite magnetic core and an alloy magnetic material, and an unnecessary signal is reproduced to improve the S / N of the signal. It is known to deteriorate. As a method for reducing this unnecessary signal, a method has been known in which the interface between the ferrite and the alloy magnetic film is formed so as not to be parallel to the magnetic gap, and the unnecessary signal due to the pseudo gap is reduced by the azimuth effect. However, the method of forming the interface between the ferrite and the alloy magnetic film so as to be non-parallel to the magnetic gap has a problem that the processing procedure is long and complicated because the alloy magnetic film is formed on the slope portion.
This is pointed out in the cited publication. Therefore, in the above invention, a film for preventing the diffusion of the ferrite and the alloy magnetic film is formed between them, and the pseudo gap formed at the interface is minimized,
The generation of unnecessary signals is suppressed. This eliminates the need for processing the surface on which the alloy magnetic film is formed to be non-parallel to the gap, and simplifies the processing procedure.

[0003]

However, in the above-mentioned prior art, no consideration is given to the characteristics at the time of recording, and when used for a high coercive force medium, sufficient recording cannot be performed especially in the long wavelength region. Alternatively, the phenomenon that the optimum recording current becomes large occurs. Further, this tendency tends to become stronger as the track width becomes larger, which has been a practical problem.

An object of the present invention is that the magnetic gap surface and the interface of the ferrite alloy magnetic film are parallel to each other and the processing procedure is simple.
To provide a magnetic head shape having sufficient recording characteristics in the head.

[0005]

The above object is achieved by securing a magnetic flux that reaches the gap surface during recording and obtaining a sufficient recording magnetic field strength.

[0006]

Since the alloy magnetic film having a high saturation magnetic flux density is formed to have an appropriate thickness, a sufficient magnetic flux can be transmitted to the gap surface during recording. Therefore, for high coercivity media,
It is possible to realize an MIG head having high recording characteristics even in the long wavelength region.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment using the present invention is shown in FIGS. A diffusion prevention film (2) is formed on a trapezoidal soft magnetic ferrite (1), and an alloy magnetic film (3) is formed on the diffusion prevention film (2) to form a magnetic core half body. A groove (4) for the winding coil is formed in at least one half of the magnetic core. The pair of magnetic core halves are bonded via the magnetic gap material (5) to form a magnetic circuit to form a magnetic head. The thickness of the side wall of the formed alloy magnetic film in the track width direction is a1 and a2, and the taper angles of the side wall are θ1 and θ2.
Let c be the length of the parallel portion of the trapezoidal ferrite with the magnetic gap, and b be the alloy magnetic film thickness formed thereon. The present inventors have found that a FeTaC-based alloy having a saturation magnetic flux density of 1.5 T on a Mn-Zn ferrite having a saturation magnetic flux density of 0.5 T, 1.
The recording and reproducing characteristics of the MIG head prototyped using 1T CoTaZr-based alloy and 0.9T CoNbZr-based alloy having different saturation magnetic flux densities were measured using a metal tape at a recording wavelength of 8 μm of a chroma signal of 5 μm. As a result of investigating the wavelength, it was found that the characteristics can be well explained by arranging it using α shown in Formula 1. As shown in the results in FIG. 3, although it was found that the maximum value of the reproduction output obtained depends on the saturation magnetic flux density of the alloy magnetic material, it decreases similarly with the decrease of α regardless of which alloy material is used. If α is 0.6 or more, decrease in output level is 1
It can be suppressed within dB.

As shown in FIGS. 4 and 5, the total amount of magnetic flux reaching the magnetic gap is the magnetic flux φ from the alloy slope.
1, φ2, the magnetic flux φ3 from the ferrite magnetic gap parallel portion, and φ4 flowing from the winding window side in the sliding surface direction.
Is. As for φ4, only φ5 leaks to the other magnetic core half by the time it reaches the sliding surface, and φ4-for recording.
Only φ5 is involved. φ4-φ5 is the gap depth G
Since d decreases as d increases, in order to realize excellent recording characteristics in a large Gd region, φ1, φ2, and φ
It is necessary for 3 to form the main part of the recording magnetic flux. φ1, φ
2 and φ3 are expressed as follows.

[0009]

(2) φi = ai * cos (θi) * Gd * Bsm
(I = 1, 2)

[0010]

## EQU00003 ## .phi.3 = c * Gd * Bsf The maximum recording magnetic field strength is when the gap surface of the alloy magnetic film is magnetically saturated.
given that

[0011]

## EQU4 ## φmax = Tw * Gd * Bsm.

When the ratio of φ1 + φ2 + φ3 to φmax is α, the following equation 1 is derived. The result of Fig. 3 shows that this ratio α
By configuring the MIG head to be 0.6 or more, the MIG head can realize the excellent recording characteristics by effectively utilizing the high saturation magnetic flux density of the alloy magnetic film.

The present invention is not limited to the above-described embodiments, and is similarly effective for MIG heads using various alloy magnetic films and MIG heads having no diffusion prevention layer. It is needless to say that the MIG head that effectively utilizes the high saturation magnetic flux density of 1 to realize excellent recording characteristics.

[0014]

According to the present invention, since a recording magnetic flux that generates a sufficient recording magnetic field strength can be obtained in an MIG head using a high saturation magnetic flux density alloy, even when applied to a high coercive force medium, It is possible to obtain a satisfactory reproduction output with sufficient recording ability.

[Brief description of drawings]

FIG. 1 is a plan view showing a sliding surface shape of the present invention.

FIG. 2 is a perspective view showing the external appearance of the head of the present invention.

FIG. 3 is a diagram showing characteristics of a prototype MIG head.

FIG. 4 is a schematic diagram illustrating a magnetic flux on a sliding surface during recording.

FIG. 5 is a schematic diagram illustrating a flow of recording magnetic flux in the vicinity of a gap.

[Explanation of symbols]

1 ... Soft magnetic ferrite, 2 ... Diffusion prevention layer, 3 ... Alloy magnetic film, 4 ... Winding window, 5 ... Magnetic gap material, φ1, φ2,
φ3, φ4, φ5 ... Magnetic flux.

Claims (1)

[Claims] A soft magnetic ferrite having a saturation magnetic flux density Bsf having a plane parallel to a magnetic gap and magnetic core halves made of an alloy magnetic material having a saturation magnetic flux density Bsm deposited on the soft magnetic ferrite are provided with a gap material. In the magnetic head that abuts via the above, at least the side wall film thicknesses a1 and a2, the side wall taper angles θ1 and θ2 of the alloy magnetic film on the trailing side of the tape, the alloy magnetic film thickness b on the parallel surface of the gap, The length c in the track width direction on the plane parallel to the gap is calculated by the following equation with respect to the track width Tw
A magnetic head characterized in that α defined by is set to 0.6 or more. [Equation 1] α = {(a1 * cos (θ1) + a2 * cos (θ2)) * Bsm + c * Bsf} / (Tw * Bsm)