JPH05101340A - Combined type magnetic head - Google Patents

Abstract

(57) [Abstract] [Purpose] To suppress the baseline amplitude fluctuation of the reproduction output of the composite type magnetic head and reduce the peak shift caused thereby. The magnetic permeability of the magnetic pole 20 of the inductive recording head is set to 1/50 or less of the magnetic permeability of the upper shield film 21 and the lower shield film 24 of the MR reproducing head. [Effect] Since the amplitude fluctuation of the baseline of the composite magnetic head can be suppressed, there is an effect of reducing the peak shift caused thereby.

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.

[0002]

2. Description of the Related Art A composite magnetic head has a high degree of freedom in design because recording / reproducing is separated. Particularly, when an MR type is used for reproducing, a high reproducing sensitivity can be obtained. A combined head of a recording head and an MR reproducing head is used. However, since the magnetic pole of the recording head has a high magnetic permeability and is installed close to the shield film of the MR reproducing head, the baseline of the output waveform of the MR reproducing head undergoes amplitude fluctuation, which increases the peak shift. There are drawbacks.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the baseline amplitude fluctuation of the output waveform of the MR reproducing head.

[0004]

In order to suppress the amplitude fluctuation of the output waveform baseline, the magnetic permeability of the recording head magnetic pole is set to M.
The magnetic permeability may be lower than the magnetic permeability of the R read head shield film.

[0005]

In order to know the ratio between the magnetic permeability of the recording head magnetic pole and the magnetic permeability of the MR reproducing type head shield film, the magnetic permeability of the MR reproducing type head shield film is fixed at 1000 and the magnetic permeability of the recording head magnetic pole is changed. Type magnetic head was prototyped and examined. The magnetic permeability is adjusted by adjusting the composition of Fe and Ni to 100
0,300,50,20,10 were obtained. Observation of the MR reproduction output waveform shows that if the magnetic permeability is 20 or less, the amplitude of the baseline of the output waveform is not affected, and the ratio of the magnetic permeability of the recording head magnetic pole to the magnetic permeability of the MR reproduction type head shield film is set to 1. It was found that it should be set to / 50 or less.

[0006]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a cross-sectional view of the composite head used in the examples. On the slider substrate 25, the lower shield film 24, the Nb shunt film 23, Fe
The Ni-MR film 22 and the upper shield film 21 were laminated to form an MR head, and further the coil 26 and the recording magnetic pole 20 were laminated to form a recording head to finally form a composite head. A sputtering method was used for fabrication. The thickness of the shield film is 1.5 μm for both the upper and lower parts, the Nb shunt film 23,
The FeNi-MR film 22 has a thickness of 50 nm (nanometers) and 20 nm, respectively, and the interlayer insulating film is an alumina film. The recording magnetic pole 20 is made of FeNi material and has a film thickness of 2.3.
μm.

FIG. 2 is a diagram used for measuring a reproduction output waveform and an operation margin when a composite head is used.
3 is a connection diagram of a 5-inch magnetic disk device 1 and a control device 2. FIG. Recording / reproduction was performed by combining a Co type sputter medium 3 having a saturation magnetization of 9000 G (Gauss), a magnetic film thickness of 30 nm and a coercive force of 2000 Oe (Oersted) with the composite magnetic head 4 shown in FIG. 2 at a flying height of 0.15 μm. The recording frequency is 9 MHz (megahertz). First, the recording / playback switching amplifier 6 is instructed by the control device 2.
Data recording is performed on the Co-based sputter medium 3 via the recording head via. At the time of reproduction, after the reproduction head output is waveform-shaped by the recording / reproduction switching amplifier 6 and the equalizer 7, the limiter 8, the pulse conversion circuit 9, the step removal circuit 10, the discrimination circuit 1
The data is demodulated by 1 and sent to the control device 2.

The reproduction output waveform was observed at the input of the equalizer 7, and the operation margin was measured at the controller 2.

FIG. 3 shows a reproduction output waveform when the bit length is 2.5 μm, and the waveform of the magnetic permeability of the magnetic pole of the recording head is 20 according to this embodiment. In the case of not implementing the present invention, the waveform of a normal magnetic permeability of 1000 is subject to amplitude fluctuations in the baseline due to the influence of the magnetic pole of the recording head.

FIG. 4 shows the result of measuring the operation margin in this embodiment, where there is no displacement. Discrimination window width is 27
ns (nanosecond) with operating margin of 30
%Met. In contrast, FIG. 5 shows the case where the magnetic permeability is 1000 when the present invention is not carried out. The effect of the amplitude fluctuation of the baseline appears as an increase in peak shift, and the working margin of the present invention is higher by 15%.

As described above, this embodiment can suppress the amplitude fluctuation of the baseline, reduce the peak shift caused thereby, and expand the operation margin.

[0012]

According to the present invention, the amplitude fluctuation of the baseline of the composite magnetic head can be suppressed, so that the peak shift caused thereby can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a composite head used in an example of the present invention.

FIG. 2 is a block diagram of an apparatus for measuring the effect of the embodiment of the present invention.

FIG. 3 is a reproduction output waveform diagram obtained when the present invention is implemented and when it is not implemented.

FIG. 4 is an explanatory diagram showing an operation margin measurement result when the present invention is implemented.

FIG. 5 is an explanatory diagram showing an operation margin measurement result when the present invention is not implemented.

[Explanation of symbols]

24 ... Lower shield film, 22 ... FeNi-MR film, 21
... Upper shield film, 20 ... Recording head magnetic pole.

Claims (2)

[Claims] 1. In a magnetic head in which an inductive recording head and an MR reproducing head are combined, the magnetic permeability of the shield film of the MR head is 1/50 of the magnetic permeability of the magnetic pole film of the inductive head.
A composite magnetic head characterized by the following. 2. A magnetic recording device equipped with the composite magnetic head according to claim 1.