JPH05101328A - Magnetic head - Google Patents

Abstract

PURPOSE:To empirically obtain the combination of crystal bearings of a main magnetic path constituting surface and a gap forming surface in the case of using of a single crystal ferrite core material in order to solve the problem of a pseudo gap of a parallel type MIG head and to improve recording and reproducing outputs. CONSTITUTION:This magnetic head is constituted by forming ferromagnetic metallic thin films 3a, 3b on the gap forming surface 101 of at least one magnetic core half body of a pair of the magnetic core half bodies 1a, 1b consisting of the single crystal ferrite and butting this ferromagnetic metallic thin film and the other magnetic core half body via a nonmagnetic material which is a magnetic gap 4. The crystal face of the main magnetic path constituting surface 103 of the magnetic core half body formed with the above-mentioned ferromagnetic metallic thin film is formed of about {211}. The angle of constituted by the vector A of the direction which is parallel with the <110> crystal axis within the material path constituting surface and is further from the gap forming surface and the vector B of the direction which is parallel with the intersected line of the main magnetic path constituting surface and the gap forming surface and is near the recording medium-facing surface is specified to a 0 to 60 deg. or 150 to 18 deg. range.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a VTR, DAT, HDD
The present invention relates to a magnetic head used in a magnetic recording / reproducing apparatus such as the above.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording / reproducing apparatus such as a VTR, temporal recording density is improved (frequency band is increased).
And improvement of spatial recording density (narrower track, shorter wavelength)
Is being promoted. Focusing on the point of short-wavelength recording, it is desirable to use a magnetic medium having a high coercive force in order to perform the short-wavelength magnetic recording. In addition to the high frequency characteristics and wear resistance of the magnetic core required for the head, characteristics that magnetic proximity is less likely to saturate near the gap of the magnetic core where magnetic flux concentrates during recording are required.

As a magnetic head satisfying such requirements, as shown in FIG. 3, most of the magnetic cores 1a, 1b are made of a ferromagnetic oxide having excellent high frequency characteristics, and the gaps of the cores 1a, 1b are butted. There is known a magnetic head having a MIG (Metal In Gap) structure in which ferromagnetic metal thin films 3a and 3b having a high saturation magnetic flux density are arranged in a portion.

In the so-called parallel type MIG head in which the boundary surface between the ferromagnetic oxides 1a and 1b and the ferromagnetic metal thin films 3a and 3b shown in FIG. 3 is parallel to the gap surface 4, the boundary surface is pseudo. However, there is a problem in that undulation appears in the frequency characteristic curve of the recording / reproducing output as shown in FIG.
No. 3204 (G11B 5/127) is a means for solving the pseudo-gap problem, in which the perfect crystal plane is exposed on the gap forming surface of the ferromagnetic oxide core after the treatment such as mirror polishing, phosphoric acid etching and reverse sputtering. It is disclosed that the ferromagnetic metal thin films 3a and 3b are formed through the heat resistant thin films 2a and 2b having a thickness of 1 nm or more and 1/10 or less of the gap length.

Further, in JP-A-1-133204, when single crystal ferrite is used as the ferromagnetic oxide core material, the effect of the means for solving the problem of the pseudo gap depends on the crystal orientation of the ferrite core. Compared with the case where the formation surface is the {111} crystal plane of the ferrite single crystal,
It is described that the {100} crystal plane is more advantageous, but various combinations of crystal orientations of the gap forming surface and the main magnetic path forming surface are conceivable, and the parallel MI
It is not easy to predict how the effect of the recording / reproducing output of the G head and the solution to the pseudo gap problem will depend on the crystal orientation of the ferrite part, and there are few experimentally reported cases. ..

[0006]

SUMMARY OF THE INVENTION The present invention aims at solving the pseudo-gap problem and improving the recording / reproducing output in the above parallel type MIG head, and particularly uses single crystal ferrite as a ferromagnetic oxide core material of a magnetic head. On the assumption that that is the case, a more preferable crystal orientation of the single crystal ferrite core portion is clarified as compared with the combination of the main magnetic path constituting surface {110} and the gap forming surface {100} recommended in the above-mentioned publication. The purpose is to

[0007]

According to the present invention, a ferromagnetic metal thin film is formed on a gap forming surface of at least one magnetic core half of a pair of magnetic core halves made of single crystal ferrite, In a magnetic head comprising a magnetic metal thin film and the other magnetic core half body butted against each other via a non-magnetic material forming a magnetic gap, a crystal of a main magnetic path constituting surface of the magnetic core half body on which the ferromagnetic metal thin film is formed. The surface is approximately {211}
And a vector A in a direction parallel to the <110> crystal axis in the main magnetic path forming surface and away from the gap forming surface, and parallel to a line of intersection between the main magnetic path forming surface and the gap forming surface on the recording medium facing surface. The angle θ formed by the approaching vector B is 0 ° to 6
The present invention provides a magnetic head characterized by being configured as 0 ° or a range of 150 ° to 180 °.

[0008]

The inventor of the present invention has at least the purpose of solving the pseudo gap problem and improving the recording / reproducing output in the parallel type MIG head having the single crystal ferrite core in the magnetic head having the above-mentioned structure. It was experimentally found that the same or more effective effects are exhibited as compared with the parallel type MIG head having the main magnetic path constituting surface {110} / gap forming surface {100} recommended in.

[0009]

EXAMPLE An example of the present invention will be described in detail below with reference to the background of the experiment leading to the present invention. The inventor of the present application has found that the ferromagnetic MIG head is composed of single crystal ferrites having various crystal orientations as shown in Table 1, and has the external shape and cross-sectional shape as shown in FIG. Was prototyped according to the specifications shown in Table 2, and the undulation of the frequency characteristic curve (hereinafter referred to as F special undulation) and the recording / reproducing output caused by the pseudo gap problem are shown in Table 3
The measurement results shown in are obtained.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

Treatment conditions for the gap forming surface in Table 2
The conditions for forming the heat-resistant thin film are described in JP-A-1-13320.
This is in accordance with the solution to the pseudo gap problem disclosed in No. 4.

The meanings of the main magnetic path forming surface, the gap forming surface, and the recording medium facing surface in Table 1 follow the convention of those skilled in the art, and the surfaces 103, 101 and 10 shown in FIG.
2 corresponds to 2 respectively, but in more detail, the gap forming surface 101 and the ferromagnetic metal thin films 3a and 3b in the MIG head to which the present invention is applied are butted against the other magnetic core half body via a non-magnetic material. The main magnetic path forming surface 103 means a surface including the shortest magnetic path that goes around the winding hole of the head and is perpendicular to the gap forming surface 101. The facing surface 102 means a surface perpendicular to the gap forming surface 101 and perpendicular to the main magnetic path forming surface 103.

Since the main magnetic path forming surface 103, the gap forming surface 101, and the recording medium facing surface 102 are surfaces orthogonal to each other, the crystal orientation of the other one surface is determined by determining the crystal orientation of any two surfaces. Inevitably decided.

Table 1 shows the above-mentioned JP-A-1-133.
The crystal orientation recommended in No. 204 is a comparative example with the present invention.

Table 1 shows the main magnetic path forming surface {11 which is often used in the VCR single crystal ferrite head.
0}, gap forming surface {111}, recording medium facing surface {2
11} is a direction in which the main magnetic path forming surface and the recording medium facing surface are exchanged with reference to the crystal orientation of 11}. In Table 1
Is an orientation in which the main magnetic path forming surface is fixed and the gap forming surface and the recording medium facing surface are changed to other main crystal surfaces, that is, crystal surfaces having a surface index as small as possible.

Here, the main magnetic path forming surface, the gap forming surface, and the recording medium facing surface in and of Table 1 are expressed by the same surface index, but the magnetic paths are asymmetric in the main magnetic path forming surface. As is clear from the consideration of the asymmetry and the asymmetry of various crystal axes in the {211} plane, they are not equivalent. In order to distinguish them, as a means for expressing the crystal orientation, a vector A that is parallel to the <110> crystal axis in the {211} crystal plane that constitutes the main magnetic path constituting plane and is away from the gap forming plane, Assuming a vector B in a direction parallel to the line of intersection of the main magnetic path forming surface and the gap forming surface and approaching the recording medium facing surface, an angle θ formed by both vectors (see FIG. 1)
The value of is used.

The F waviness and the recording / reproducing output in Table 3 were measured under the condition that an iron oxide tape having a coercive force of 9000e was used as a recording medium and the relative running speed of the tape to the head was 5.8 m / s. Further, in the measurement of the F waviness, the frequency sweep signal of 0.1 to 10 MHz is recorded, and the peak in the vicinity of 3 to 7 MHz of the frequency characteristic curve as shown in FIG. 4 obtained by detecting the reproduction output with the spectrum analyzer The output ratio of the valley was calculated. In the measurement of the recording / reproducing output, a 5 MHz sine wave was recorded without bias, the maximum reproducing output value in the reproducing output-recording current curve was obtained, and standardized with the value of the comparative example.

The data in Table 3 are interpreted as follows.

Regarding the F-specific waviness, the F-specific wavinesses of ~ are smaller than those of ~, but are larger than those of the comparative examples. However, general common sense of those skilled in the art regarding F-specific waviness (MI for digital magnetic recording / reproducing devices such as DAT and HDD)
The permissible upper limit of F waviness in the G head is about 2 dB, and MI for analog magnetic recording / reproducing devices such as home VTRs.
According to the permissible upper limit value of the F characteristic waviness in the G head is about 1 dB), if the F characteristic waviness is about to, there is no practical problem.

Regarding the recording / reproducing output, the outputs of to and are obviously higher than those of the comparative example, and particularly, the output is high.

From the above experimental results, the inventor of the present application said, "A ferromagnetic metal thin film is formed on the gap forming surface of at least one of the pair of magnetic core halves made of single crystal ferrite, and In a magnetic head comprising a magnetic metal thin film and the other magnetic core half body butted against each other via a non-magnetic material forming a magnetic gap, the crystal orientation of the magnetic core half body on which the ferromagnetic metal thin film is formed is By setting either of them, an excellent effect can be obtained in terms of solving the pseudo gap problem and recording / reproducing output, as compared with the case of setting the above as recommended in JP-A-1-133204. The gist of the present invention has been derived.

Further, the inventor of the present application has made it
Based on FIG. 2 in which the values of the special waviness and the recording / reproducing output are plotted with respect to the value of θ, the continuity of the physical quantity is also taken into consideration.
It was estimated that "if θ is set in the range of 0 ° to 60 ° or 150 ° to 180 °, the characteristics equal to or higher than the above-mentioned are obtained as a comprehensive evaluation of the F waviness and the recording / reproducing output."

The above-described effect peculiar to the present invention does not reflect the synergistic effect due to the fact that the crystal orientations of the single-crystal ferrites constituting the core halves on both sides are the same, but one core half on each side. Since it is considered that it is due to the superposition of the action effects in each body, the present invention is applied to at least one core half even if the single crystal ferrites forming the core half on both sides have different crystal orientations. Then, the effect obtained by superimposing the action and effect peculiar to the present invention on the core half body and the characteristic of the other core half body should be obtained.

The MIG head to which the present invention is applied is shown in FIG.
The present invention is not limited to the head having the external shape as described above, but includes a head having a recording medium facing surface structure as shown in FIG. 5, for example. FIG. 5 (a) is an MIG head in which a ferromagnetic metal thin film 3a is formed only on one core half 1a, and FIG. 5 (b) is a film of the ferromagnetic metal thin films 3a, 3b on both side core halves 1a, 1b. MIG heads having different thicknesses, FIG. 5C shows the ferrite core portions of the core halves 1a and 1b and the ferromagnetic metal thin film 3.
This shows a MIG head in which the boundary surface between a and 3b is not completely parallel to the abutting surface of the gap 4.

[0027]

As described above, the magnetic head according to the present invention has at least the object of solving the pseudo-gap problem and improving the recording / reproducing output in the parallel type MIG head having the single crystal ferrite core portion. Compared with the parallel type MIG head having the main magnetic path constituting surface {110} / gap forming surface {100} recommended by the technology, the same or more effective effects are exhibited.

[Brief description of drawings]

FIG. 1 is a diagram showing a crystal orientation of a main magnetic path constituting surface of a magnetic head of the present invention.

FIG. 2 is an experimental result diagram for explaining the F characteristic waviness and the crystal orientation dependence of the recording / reproducing output.

FIG. 3 is an external perspective view of a magnetic head for explaining a conventional example and an example of the present invention.

FIG. 4 is an F characteristic waviness diagram for explaining a conventional problem.

FIG. 5 is a plan view for explaining another embodiment of the recording medium facing surface of the magnetic head of the present invention.

[Explanation of symbols]

 1a, 1b Magnetic core half body 101 Gap forming surface 103 Main magnetic path forming surface 3a, 3b Ferromagnetic metal thin film 4 Magnetic gap

Claims (1)

[Claims] 1. A ferromagnetic metal thin film is formed on the gap forming surface of at least one magnetic core half of a pair of magnetic core halves made of single crystal ferrite, and the ferromagnetic metal thin film and the other magnetic core are formed. In a magnetic head formed by abutting a half body with a non-magnetic material forming a magnetic gap, the crystal plane of the main magnetic path forming surface of the magnetic core half body on which the ferromagnetic metal thin film is formed is approximately {211}, A vector A in a direction parallel to the <110> crystal axis in the main magnetic path constituting surface and away from the gap forming surface, and a direction parallel to a line of intersection between the main magnetic path constituting surface and the gap forming surface and approaching the recording medium facing surface. Angle θ formed by vector B of 0 ° to 60 ° or 150 ° to 1
A magnetic head characterized by being configured as a range of 80 °.