JP2762795B2 - Composite magnetic head - Google Patents

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 good magnetic recording and reproduction efficiency used for a VHS (registered trademark) type VTR.

[0002]

2. Description of the Related Art In recent years, the start of satellite broadcasting, CD and DA
With the introduction of markets such as T, 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 has been advanced.

In this system, in order to maintain compatibility with the S-VHS system, the format of video and audio is not changed, and the magnetic head has an azimuth angle of ± 30 as in the prior art.
The use of a rotating head dedicated to ° voice. The recording method is as follows.
Digital audio signal modulated by PSK (Quadrature Phase Shift Keting), 1.3MHz, 1.7MHz
Is multiplexed and recorded on a 12 MHz bias signal, and a video signal is overwritten on the surface layer.

FIG. 5A shows the frequency allocation of a video signal recorded on the surface layer of a magnetic tape.
(B) is a diagram showing frequency allocation of an audio signal recorded in a deep part.

Further, a magnetic head for recording and reproducing an audio signal is required to have a wider band and higher sensitivity, and a composite 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 includes a pair of magnetic cores 12 made of a ferrite single crystal excellent in wear resistance and high-frequency characteristics of magnetic permeability. A soft magnetic layer 13 made of sendust, amorphous or the like having a high saturation magnetic flux density formed on the butted surfaces of the pair of magnetic cores 12 and a filled glass 14.

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

[0008]

However, as a peculiar phenomenon of the conventional composite type magnetic head 10 for audio, there is a phenomenon in which a signal is recorded on a surface layer of a magnetic tape during a reproduction spectrum of an audio signal recorded on a deep layer of the magnetic tape. High frequency crosstalk of the resulting color signal, which results in 3 ± 1
There has been 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 is a spectrum of a reproduced signal when a magnetic tape on which a video signal is recorded on a surface layer is reproduced by a conventional composite magnetic head 10.

The video signal recorded on the magnetic tape is recorded under the following conditions in order to slightly enhance crosstalk.

(1) Sine wave of 6.5 MHz for luminance signal (set to optimum recording level) (2) Sine wave of 629 KHz (set to normal 6 dB up recording level) According to FIG. Large crosstalk of color signal and crosstalk (harmonic) of its second harmonic or more
Is appearing. The crosstalk of these second harmonics or more is 3
This affects digital audio signals existing at ± 1 MHz.

The cause of the crosstalk of the second harmonic or higher occurs because a pseudo gap on the tape sliding surface of the composite magnetic head 10 reproduces a video signal of a track recorded on the surface layer of the magnetic tape. It is considered something.

FIG. 8 is an enlarged plan view of a main part of a tape sliding surface of the conventional composite magnetic head 10, and FIG. 9 shows that the composite magnetic head 10 records data on a magnetic tape at a track pitch of 19.3 μm. The resulting signal tracks are transferred to the pseudo gap 16.
FIG. 6 is a diagram for explaining a phenomenon in which the image is reproduced.

As shown in FIG.
Since a magnetically degraded layer is formed at the interface between the metal soft magnetic layer 13 and the magnetic core 12 due to a thermal diffusion reaction, the interface acts as a pseudo gap 16. For this reason, the transmission system through which the reproduction signal passes is a gap 15 and a pseudo gap 16, and the azimuth angle of the track 17 of the video signal already recorded on the magnetic tape is ± 6 ° and the pseudo-gap of the composite magnetic head 10 described above. At the portion 18 where the azimuth angles of the gap 16 are substantially the same, there is a problem that the video signal of the track 17 is reproduced to cause crosstalk.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is a composite type magnetic head comprising a head chip half having a joining surface in which a magnetic core and a metal soft magnetic layer are joined, butted through a gap. A head, wherein the joining surface of the head chip half includes a first linear portion perpendicular to a gap line, and a second linear portion extending to the first linear portion and perpendicular to the gap line. And the second part
A third linear portion extending to the linear portion and having an angle θ of 20 ° or more with respect to the gap line, and a surface sliced to provide an azimuth angle in the gap at the time of manufacturing the head, It is an object of the present invention to provide a composite magnetic head, wherein a triangular shape is formed with three sides including a second linear portion, the third linear portion, and the sliced surface.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 a calculation result of azimuth loss, wherein the track width W of a signal recorded on a magnetic tape is set to 19.
When the gap is set to 3 μm (EP mode), the change in the azimuth loss Lθ with respect to the azimuth angle θ of the gap is expressed by the fundamental component of the crosstalk (fs = 629 KHz) and the second harmonic (2f
s) Calculation results for the third harmonic (3 fs).
It can be seen from the figure that the loss becomes maximum when the angle of the pseudo gap with respect to the azimuth angle of the magnetic head is 25 °, 44 °, 55 °,....

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

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

FIG. 2 is an enlarged plan view of a main part of the tape sliding surface of the composite magnetic head 30 according to the present invention, and the same components as those in FIG. .

The composite magnetic head 30 of the present invention comprises a pair of magnetic cores 12 made of a ferrite single crystal having high abrasion resistance and magnetic permeability and excellent in high frequency characteristics, similarly to the conventional composite magnetic head 10. A metal soft magnetic thin film 13 made of an amorphous alloy, sendust or the like that can realize a high saturation magnetic flux density and is formed on the butted surfaces of the pair of magnetic cores 12.
And a head chip 31 composed of the filled glass 14 and a winding.

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

Therefore, there is no portion where the azimuth angle .theta. Of the pseudo gap 16 of the composite magnetic head 10 of the present invention is substantially the same as the azimuth angle. ± .6 degrees of the track of the video signal already recorded on the magnetic tape. It is possible to solve the bad phenomenon of reproducing the track of the video signal.

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

A pair of ferrite core halves (hereinafter, simply referred to as core halves) 32a and 32b having track width regulating grooves 33a and 33b for forming a track portion are provided on mating surfaces 34a and 34b, for example, by an amorphous material. A soft metal layer 13 of 3 to 5 μm, such as Sendust,
A gap layer 35 of 0.175 μm of Al203, Si02 or the like is formed and laminated by using a sputtering method or the like. The mating surface 3 of a pair of core halves 32a and 32b in which the metal soft magnetic layer 13 and the gap layer 35 are laminated.
At the same time, the glass 14 is melted and the two core halves 32a and 32b are fused and integrated.
The magnetic head block 36 is obtained by flowing the glass 14 into the track width regulating grooves 33a, 33b at regular intervals. The tape sliding surface 37 of the combined magnetic head block 36
And the magnetic head block 36 is sliced obliquely along the illustrated dotted line to provide an azimuth angle of 30 ° to obtain a head chip 31. Thus, FIG.
As is apparent from the above, the second straight portion 21 and the third straight portion 22
And the sliced surface is triangular with three sides. Further, the coil 38 is wound around the winding window 37 of the head chip 31 to complete the composite 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 magnetic head 10.

Comparing FIG. 4 with FIG. 7, the crosstalk of the second harmonic of the 629 KHz color signal which affects the digital audio signal existing at 3 ± 1 MHz in the spectrum of FIG. It can be seen that it has been reduced.

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

[0031]

As described above, there is provided a composite magnetic head in which a head chip half having a joining surface in which a magnetic core and a metal soft magnetic material layer are joined is abutted via a gap. The joining surface of the body includes a first straight section perpendicular to the gap line, a second straight section extending to the first straight section and perpendicular to the gap line; A third straight portion extending to the straight portion and having an angle θ of 20 ° or more with respect to the gap line;
A triangular shape formed by slicing a surface to provide an azimuth angle in the gap at the time of manufacturing the head, wherein the second linear portion, the third linear portion, and the sliced surface are three sides; With the composite magnetic head characterized by the above, there is no pseudo gap parallel to the azimuth angle of the track of the video signal overwritten on the tape. 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 is at least one.
2 dB could be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram of a calculation result of azimuth loss.

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

FIG. 3 is a perspective view showing one embodiment of a method of manufacturing a composite magnetic head according to the present invention.

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

5A is a diagram illustrating a frequency allocation of a video signal recorded in a surface portion, and FIG. 5B is a diagram illustrating a frequency allocation of an audio signal recorded in a deep 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 a main part of a tape sliding surface of a conventional composite magnetic head.

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

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-303613 (JP, A) JP-A-2-53214 (JP, A) JP-A-1-109807 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) G11B 5/23 G11B 5/187

Claims (1)

(57) [Claims] 1. A head chip half (31a, 3) having a joining surface (16) joining a magnetic core (12) and a metal soft magnetic layer (13).
A composite magnetic head 30 formed by abutting the head chips 1b via a gap 15, wherein the bonding surface 16 of the head chip halves 31a and 31b is
Is a first linear portion 20 perpendicular to the gap line G.
A second linear portion 21 extending to the first linear portion 20 and perpendicular to the gap line G; and a second linear portion 21 extending to the second linear portion 21 and extending 20 ° to the gap line G. The third linear portion 22 having the above angle θ and the head
To provide an azimuth angle in the gap 15 during manufacturing
The second straight portion 21 and the front surface
The third straight line portion 22 and the sliced surface are three sides.
A composite type magnetic head 30 characterized by forming a triangular shape by using the same.