JPH0589427A - Combined magnetic head - Google Patents

Abstract

PURPOSE:To enhance the reproducing sensitivity of a combined magnetic head and to reduce noise. CONSTITUTION:Head chip half-bodies 31a, 31b each having a joined face 16 formed by joining a soft magnetic metal layer 13 to a magnetic core 12 are butted with a gap 15 in-between to obtain a combined magnetic head 30. The joined face 16 consists of a first straight line part 20 perpendicular to a gap line G, a second straight line part 21 extending from the first part 20 and perpendicular to the gap line G and a third straight line part 22 extending from the second part 21 and having >=20 deg. angle to the gap line G.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic head, and more particularly to a composite magnetic head for PCM audio having a high magnetic recording / reproducing efficiency used in a VHS (registered trademark) VTR.

[0002]

2. Description of the Related Art In recent years, the start of satellite broadcasting, CD and DA
With the market introduction of T and the like, digital audio technology has become more widely used. In order to cope with such a trend of the times, development of an S-VHS digital audio system is in progress.

In order to maintain compatibility with the S-VHS system, this system does not change the video and audio formats, and the magnetic head has an azimuth angle of ± 30 as in the conventional case.
It uses a rotary head dedicated to voice. The recording method is as follows:
PSK (Quadrature Phase Shift Keting) modulated digital audio signal and 1.3MHz, 1.7MHz
The FM audio signal is put on a 12 MHz bias signal for multiple recording, and the video signal is overwritten on the surface layer.

FIG. 5A shows the frequency allocation of the video signal recorded on the surface layer of the magnetic tape.
FIG. 3B is a diagram showing frequency allocation of a voice signal recorded in the deep layer.

[0005] Further, a wider band and higher sensitivity are required for an audio magnetic head for recording / reproducing an audio signal, and a composite type magnetic head is used.

FIG. 6 is a perspective view of a conventional example of a head chip 11 of a composite type magnetic head 10, which is composed of a pair of magnetic cores 12 made of a ferrite single crystal excellent in wear resistance and high frequency characteristics of magnetic permeability. The metal soft magnetic layer 13 made of sendust or amorphous having a high saturation magnetic flux density and formed on the abutting surfaces of the pair of magnetic cores 12 and the filled glass 14.

The composite magnetic head 10 in which the head chip 11 is wound has excellent recording performance even in a narrow gap width specification, and is particularly advantageous for wide band magnetic recording / reproduction in deep recording of a magnetic tape. Is.

[0008]

However, as a phenomenon peculiar to the conventional composite type magnetic head 10 for audio, recording in the surface layer portion of the magnetic tape in the reproduction spectrum of the audio signal recorded in the deep layer portion of the magnetic tape. High-frequency crosstalk of the generated color signal appears, which causes 3 ± 1
There is a problem that the C / N ratio of the digital audio signal of the QPSK (Quadrature Phase Shift Keting) modulated signal of MHz deteriorates, and as a result, the block error rate increases.

This problem will be described in detail.

FIG. 7 shows a spectrum of a reproduction signal when a magnetic tape on which a video signal is recorded on the surface layer is reproduced by the conventional composite magnetic head 10.

The video signal recorded on the magnetic tape is recorded under the following conditions in order to emphasize crosstalk to some extent.

(1) Luminance signal of 6.5 MHz sine wave (set to optimum recording level) (2) Color signal of 629 KHz sine wave (setting to normal 6 dB up recording level) According to FIG. 7, 629 KHz Large color signal crosstalk, and crosstalk of more than the second harmonic (harmonics)
Is appearing. Crosstalk above these 2nd harmonic is 3
It affects digital audio signals present at ± 1 MHz.

The cause of the crosstalk of two or more harmonics is that the pseudo gap on the tape sliding surface of the composite magnetic head 10 reproduces the video signal of the track recorded on the surface layer of the magnetic tape. Thought to be a thing.

FIG. 8 is an enlarged plan view of an essential part of a tape sliding surface of a conventional composite magnetic head 10, and FIG. 9 shows the composite magnetic head 10 recording on a magnetic tape at a track pitch of 19.3 μm. The signal track that has been
FIG. 6 is a diagram illustrating a phenomenon that is reproduced.

As shown in the figure, the composite magnetic head 10 is shown.
Causes a magnetically deteriorated layer due to a thermal diffusion reaction at the interface between the metal soft magnetic layer 13 and the magnetic core 12, so that the interface acts as the pseudo gap 16. Therefore, the transmission system through which the reproduction signal passes is the gap 15 and the pseudo gap 16, and the azimuth angle ± 6 ° of the track 17 of the video signal already recorded on the magnetic tape and the pseudo of the composite magnetic head 10 described above. There is a problem that the video signal of the track 17 is reproduced at the portion 18 where the azimuth angle of the gap 16 is almost the same to cause crosstalk.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a head chip half body having a joint surface in which a magnetic core and a metal soft magnetic material layer are joined is provided with a gap. And a joint surface of the head chip half, the first straight line portion being perpendicular to the gap line and the first straight line portion extending to the gap line. A composite type comprising a second straight line portion perpendicular to the second straight line portion and a third straight line portion extending to the second straight line portion and having an angle θ of 20 ° or more with respect to the gap line. It is intended to provide a magnetic head.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has been made to solve the problem caused by the pseudo gap 16 of the composite magnetic head 10 described above.

FIG. 1 is a diagram showing the calculation result of the azimuth loss. The track width W of the signal recorded on the magnetic tape is 19.
When it is set to 3 μm (EP mode), the change of the azimuth loss Lθ with respect to the azimuth angle θ of the gap is calculated by measuring the fundamental wave component of crosstalk (fs = 629 KHz)
s) Results obtained by calculating the third harmonic (3fs).
It can be seen from the figure that the maximum loss occurs when the pseudo gap angle with respect to the azimuth angle of the magnetic head is 25 °, 44 °, 55 °, ....

However, the number of tracks reproduced in the pseudo gap is not necessarily an integer, and the actual color signal is ± 5.
It is thought that it is difficult to select a precise angle due to the fact that it has a band of 00 KHz, but if the angle θ is 20 ° or more with respect to the gap line, at least a loss effect of 17 dB can be expected in the fundamental wave component. Be done.

The composite magnetic head 30 of the present invention is made based on the above calculation results.

FIG. 2 is an enlarged plan view of an essential part of the tape sliding surface of the composite magnetic head 30 of the present invention. The same components as those of FIG. 8 described above are designated by the same reference numerals. ..

Like the conventional composite magnetic head 10, the composite magnetic head 30 of the present invention has a pair of magnetic cores 12 made of a ferrite single crystal having high wear resistance and magnetic permeability and excellent in high frequency characteristics. A metal soft magnetic thin film 13 such as an amorphous alloy or sendust, which can realize a high saturation magnetic flux density, is formed on the abutting surfaces of the pair of magnetic cores 12.
The head chip 31, which is composed of the glass 14 and the filled glass 14, is wound.

The joining surface of the magnetic core 12 and the metal soft magnetic material layer 13 on the tape sliding surface of the head chip 31 has a first straight line portion perpendicular to the gap line G and a first straight line portion. From a second straight portion extending and perpendicular to the gap line G, and a third straight portion extending to the second straight portion and forming an angle of 20 ° or more with the gap line G. A pair of head chip halves 31a, 31
a is formed to be antisymmetric with respect to the gap line G via the gap 15.

Therefore, there is no portion where the azimuth angle ± 6 ° of the track of the video signal already recorded on the magnetic tape and the azimuth angle θ of the pseudo gap 16 of the composite magnetic head 10 of the present invention are substantially the same. It is possible to solve the bad phenomenon that the track of the video signal is reproduced.

FIG. 3 is a perspective view showing an embodiment of a method of manufacturing the composite type magnetic head 30 of the present invention. Hereinafter, description will be given with reference to FIG.

A pair of ferrite core halves (hereinafter, simply referred to as core halves) 32a, 32b having track width regulating grooves 33a, 33b for forming a track portion are provided on the abutting surfaces 34a, 34b of, for example, amorphous, A metal soft magnetic material layer 13 of 3 to 5 μm, such as sendust,
The gap layer 35 made of 0.175 μm such as Al ₂ O ₃ or SiO ₂ is formed and laminated by a sputtering method or the like. Butt face 3 of a pair of core halves 32a, 32b in which the metal soft magnetic layer 13 and the gap layer 35 are laminated.
4a and 34b are butted against each other, the glass 14 is melted and both core halves 32a and 32b are fused and integrated,
The magnetic head block 36 is obtained by allowing the glass 14 to flow into the track width regulating grooves 33a and 33b at regular intervals. The tape sliding surface 37 of the joined magnetic head block 36
Is subjected to R surface processing, and the magnetic head block 36 is sliced along the dotted line shown in the drawing in an oblique direction to provide an azimuth angle of 30 ° to obtain a head chip 31. Further, the coil 38 is wound around the winding window 37 of the head chip 31 to complete the composite magnetic head 30.

A reproduction spectrum using the above-described composite magnetic head 30 of the present invention is shown below.

FIG. 4 shows a spectrum when a magnetic tape on which a video signal is recorded is reproduced by the composite magnetic head 30 of the present invention. The magnetic tape on which this video signal is recorded is the same as that used for measuring the reproduction spectrum of the conventional composite type magnetic head 10.

Comparing this FIG. 4 with FIG. 7, crosstalk of the second harmonic wave or more of the color signal of 629 KHz affecting the digital audio signal existing at 3 ± 1 MHz existing in the spectrum of FIG. You can see that it is decreasing.

From these results, the conventional composite magnetic head 1
The problem of the pseudo gap, which was a problem at 0, was solved, and high-frequency crosstalk more than the second harmonic of the color signal existing in the spectrum of the reproduced audio signal was 12 dB.
Could be reduced.

[0031]

As described above, the composite magnetic head is obtained by abutting the head chip halves having the joint surface in which the magnetic core and the metal soft magnetic layer are joined to each other through a gap. The joint surface of the body has a first straight line section perpendicular to the gap line, a second straight line section extending to the first straight line section and perpendicular to the gap line, and the second straight line section. By forming a composite type magnetic head comprising a third linear portion extending to the gap portion and having an angle of 20 ° or more with respect to the gap line, parallel to the azimuth angle of the track of the video signal overwritten on the tape. There is no pseudo-gap. Therefore, as shown in FIG. 3, the high frequency crosstalk of the color signal in the spectrum of the signal reproduced using the composite magnetic head of the present invention could be reduced by at least 12 dB.

[Brief description of drawings]

FIG. 1 is a diagram showing calculation results of azimuth loss.

FIG. 2 is an enlarged plan view of an essential part of a tape sliding surface of the composite magnetic head of the present invention.

FIG. 3 is a perspective view showing an embodiment of the method for manufacturing the composite magnetic head of the present invention.

FIG. 4 is a video signal reproduction spectrum of the composite magnetic head of the present invention.

5A is a diagram showing frequency allocation of a video signal recorded in a surface layer portion, and FIG. 5B is a diagram showing a frequency allocation of an audio signal recorded in a deep layer portion.

FIG. 6 is a perspective view of a conventional example of a head chip of a composite magnetic head.

FIG. 7 is a video signal reproduction spectrum of a conventional composite magnetic head.

FIG. 8 is an enlarged plan view of an essential part of a tape sliding surface of a conventional composite magnetic head.

FIG. 9 is a diagram illustrating a phenomenon in which a pseudo gap of a composite magnetic head reproduces a video track.

[Explanation of symbols]

 10 Conventional composite type magnetic head 12 Magnetic core 13 Metal soft magnetic thin film 14 Glass 15 Gap 16 Pseudo gap (formation surface) 20 First straight line portion 21 Second straight line portion 22 Third straight line portion 30 Composite type of the present invention Magnetic head G Gap line

Claims (1)

[Claims] 1. Head chip halves 31a, 3 having a joint surface 16 in which a magnetic core 12 and a metal soft magnetic layer 13 are joined.
1b is a composite magnetic head 30 formed by abutting the gaps 1b with each other through a gap 15, and the joint surface 16 of the head chip halves 31a and 31b is joined.
Is a first straight portion 20 perpendicular to the gap line G.
And a second straight line portion 21 extending to the first straight line portion 20 and perpendicular to the gap line G, and 20 ° to the gap line G extending to the second straight line portion 21. A composite magnetic head 30 comprising a third straight line portion 22 having the above angle θ.