JP2000306222A - Magnetoresistance effect element reproduction evaluation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to accurately and speedily measure a track width and sensitivity distribution of a magnetic reproducing head before being assembled into a magnetic head, by providing this device with a magnetic field applying means for applying a magnetic field perpendicular to a magneto-resistance effect element, a means for obtaining a reproduction sensitivity distribution function from the magneto-resistance effect element, and a means for obtaining a reproduction track width from the reproduction sensitivity distribution function. SOLUTION: A magnetic field generating device 1 having a narrow gap d and a coil 10 is arranged to be vertical and orthogonal to a magneto-resistance effect element 2. An arbitrary signal generating device 6 inputs a rectangular waveform signal to a coil 10, and generates a magnetic field in the part of the gap d. And, when the magneto-resistance effect element 2 through which a constant current is made to flow is moved in the direction of Z, from an electrode 3a to an electrode 3d, a mean value of the peaks of reproduced output waveforms is measured with respect to the moved distance, and thus, a reproducing sensitivity distribution function of the magneto-resistance effect element 2 is obtained. It is possible to obtain an effective reproduction width of the magneto-resistance effect element 2 from the reproducing sensitivity distribution function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for evaluating and reproducing a magnetoresistance effect element. More specifically, the present invention relates to a recording / reproducing evaluation apparatus for evaluating characteristics of a thin-film magnetic head, a magnetoresistive head, a spin-valve head, and a head utilizing a giant magnetoresistive effect, which constitute a high-sensitivity magnetic recording / reproducing head. It is.

[0002]

2. Description of the Related Art In recent years, with the progress of narrower tracks accompanying the increase in density of magnetic disk devices, it has become important for a recording / reproducing evaluation device to measure the reproducing track width of a head and its sensitivity distribution.

A conventional recording / reproducing evaluation device has a magnetic recording head and a magnetic reproducing head, and a signal source and a reproducing amplifier for amplifying the signal source are connected to the recording head, and further, an input signal is observed. An oscilloscope is connected, a reproducing amplifier for amplifying the reproduced signal, a digital oscilloscope and a spectrum analyzer for viewing the reproduced signal are connected to the magnetic reproducing head, and a personal computer for processing data is connected to the digital oscilloscope. Have been.

In this personal computer, a sensitivity distribution function is predicted, an off-track characteristic is estimated by integration, and the result is compared with measured data. If the error at this time is equal to or less than a certain value, the track width is estimated from the predicted sensitivity distribution function, and if the error is large, a new sensitivity distribution function is predicted and the calculation is repeated.

However, in this configuration, since the sensitivity distribution function is re-estimated, it takes a long time to perform the calculation. Further, the calculated value of the track width for estimating the sensitivity distribution function was not accurate.

Further, another conventional recording / reproducing evaluation device has a magnetic medium, a drive system and a signal system for driving the magnetic medium,
A signal is recorded on a recording medium by a magnetic recording head connected to a signal source, and an off-track profile is obtained from a reproduction output (off-track reproduction data) when the magnetic reproduction head connected to a reproduction amplifier is moved in the width direction. The width of the left and right inclined parts is used as the track width of the reproducing head, the off-track profile is differentiated, and the obtained waveform is divided into two parts on the border of the on-track position, left-right inversion, up-down inversion, and position adjustment After adding, the sensitivity distribution function is obtained to obtain the track width of the reproducing head.

However, in this configuration, the state after the magnetic recording head and the magnetic reproducing head are integrated (HGA)
State), and the off-track reproduction data changes depending on the magnetic recording medium and the magnetic head. Therefore, when the track density becomes higher and the track becomes narrower, an accurate sensitivity distribution function and reproduction of the magnetic reproduction head are obtained. Track width cannot be measured.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned prior art, and is intended to reduce the track width and the sensitivity distribution of a magnetic reproducing head having a narrower track due to a higher density.
It is an object of the present invention to provide an apparatus for evaluating and reproducing a magnetoresistive element, which can measure accurately and at high speed before an HGA state is assembled as a magnetic head.

[0009]

In order to achieve the above object, the present invention provides a magnetic field applying means for applying a magnetic field perpendicularly to a magnetoresistive element before being incorporated into a magnetic reproducing head; An apparatus for evaluating reproduction of a magnetoresistive element, comprising: means for obtaining a reproduction sensitivity distribution function from an effect element; and means for obtaining a reproduction track width from the reproduction sensitivity distribution function.

According to this configuration, before assembling and integrating as a magnetic head, a magnetic field is applied to the magnetoresistive effect element to obtain a reproduction sensitivity distribution function, and the reproduction sensitivity distribution function is calculated accurately and by calculation from the reproduction sensitivity distribution function. The reproduction track width can be obtained at high speed.

In a preferred configuration example, the magnetic field applying means applies a magnetic field having a width narrow enough to obtain the reproduction sensitivity distribution function to the magnetoresistive element.

According to this configuration, by applying a magnetic field having a sufficiently narrow width to the magnetoresistive element, a clear reproduction sensitivity distribution function that can be processed can be obtained, and thereby an accurate track width can be obtained. it can.

In a further preferred embodiment, the magnetic field applying means comprises a coil disposed perpendicularly and perpendicular to the magnetoresistive element, and a signal applying means for applying a signal to the coil. .

According to this structure, the coil having a sufficiently narrow width is arranged perpendicularly to the orthogonal direction and a predetermined signal is applied to the magnetoresistive element as described above, whereby the magnetoresistive element is applied to the magnetoresistive element. A vertical magnetic field is generated, based on which a reproduction sensitivity distribution function is obtained.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main part configuration diagram of an embodiment of the present invention. In the present embodiment, a narrow magnetic field generating device 1 having a very narrow gap d and having a coil 10 of one or more turns is opposed to the magnetoresistive effect element 2.
It is installed so as to be perpendicular and orthogonal to the magnetoresistive element 2. The gap d is formed to be sufficiently small to enable the calculation processing of the reproduction sensitivity distribution function described later. The distance between the magnetic field generator 1 and the magnetoresistive element 2 is so small that the magnetic field generated from the magnetic field generator can sufficiently enter the magnetoresistive element 2.

The magnetic field generator 1 has a coil 10 of one or more turns, and an arbitrary signal generator 6 is connected to the coil 10. Electrodes 3a and 3b are connected to the left and right ends of the magnetoresistive element 2, respectively. An intermediate shield 4 is provided on the upper surface of the magnetoresistive element 2, and a lower shield 5 is provided on the lower surface. For example, a rectangular signal as shown in FIG. 2 is input to the coil 10 by the arbitrary signal generator 6. As a result, a magnetic field as shown in FIG. 3 is generated in the gap d. The rectangular wave of FIG. 2 is input to the magnetic field generator 1 that continuously generates such a narrow magnetic field,
In a state where a constant current is applied to the magnetoresistive element 2, the magnetoresistive element 2 is moved from one electrode 3a connected to the magnetoresistive element 2 in the width direction X to the other end 3b. When moving in the direction, the average value between the peaks of the reproduced output waveform in FIG. 3 is measured with respect to the moving distance. The result obtained in this way is as shown in FIG. 4, and the reproduction sensitivity distribution function of the magnetoresistive element 2 is obtained.

The rising and falling slopes of the reproduction sensitivity distribution function of the magnetoresistive element 2 indicate when the magnetic field generator 1 starts to be applied to the magnetoresistive element 2 or starts moving away. Therefore, the effective reproduction width of the magnetoresistive element can be obtained by calculating the width of the output of the obtained reproduction sensitivity distribution function by 50% with respect to the maximum output of the reproduction sensitivity distribution function.

FIG. 5 shows a state in which the magnetoresistive element is measured in the state of the rod-shaped row bar 9 before being assembled as a magnetic head. In the figure, each of the chips 11 is continuously measured by the magnetic field generator 1 while running in the longitudinal direction (the Z direction in FIG. 1) in the state of the row bar 9 in which three chips 11 are connected in a bar shape. Each chip 11 includes an upper core 8 and a recording coil 7 around the upper core 8, and the terminals 3a and 3b for connecting the above-described magnetoresistive element 2 are drawn out. These terminals 3
a and 3b are connected to a computer (not shown) for obtaining the above-mentioned reproduction sensitivity distribution function and analyzing the same to obtain a reproduction track width.

In this state, the electrodes 3a to 3b
A reproduction sensitivity distribution function can be obtained from a change in the reproduction output obtained when the row bar 9 is moved in the vertical direction with a current flowing through the reproduction bar, and a width of 50% of the maximum output of the reproduction sensitivity distribution function. Is calculated, the effective reproduction width can be obtained before the HGA.

FIGS. 6A and 6B show a state where the row bar 9 shown in FIG. 5 is cut for each chip and assembled as a slider of a magnetic head. FIG. 6A is a bottom view, FIG. 6B is a side view, and FIG. It is an enlarged view of the C section of A). FIG. 7 is a perspective view of a used state after being assembled as a magnetic head.

As shown in FIG. 7, the slider 20 incorporating the above-described magnetoresistive element 2 is
To form the magnetic head 24. Slider 2
Numeral 0 denotes a sliding surface (ABS surface) 21 on the side of the upper core 8 facing the recording / reproducing track surface of a magnetic recording medium 22 such as a magnetic disk.
And travels while floating on the disk surface to record and reproduce information.

[0022]

As described above, according to the present invention, before assembling and integrating as a magnetic head, a magnetic field is applied to the magnetoresistive element to obtain a reproduction sensitivity distribution function. Thus, the reproduction track width can be obtained accurately and at high speed by calculation.

That is, a magnetic field is applied perpendicularly to the magnetoresistive element by a narrow magnetic field generator having a sufficiently narrow gap with respect to the magnetoresistive recording element, and the magnetic field is applied to both ends of the magnetoresistive element while moving in the width direction. By measuring the voltage, the characteristics of a magnetic head having a magnetoresistive element can be measured and inspected without using a magnetic recording medium before forming the magnetic head, and the magnetic head manufacturing process can be performed efficiently. And increase productivity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a magnetoresistance effect element reproduction evaluation device according to the present invention.

FIG. 2 is a signal waveform diagram applied to the device of FIG.

FIG. 3 is a graph of a magnetic field generated by the signal of FIG.

FIG. 4 is a graph of a sensitivity distribution function obtained by the apparatus of FIG.

FIG. 5 is a perspective view of a reproduction evaluation device according to the present invention in a used state.

FIG. 6 is a structural explanatory view of a slider incorporating the magnetoresistive element of the present invention.

FIG. 7 is a perspective view of a magnetic head using the slider of FIG. 6;

[Explanation of symbols]

1: magnetic field generator, 2: magnetoresistance effect element, 3a, 3
b: Electrode, 4: Middle shield, 5: Lower shield, 6:
Arbitrary signal generator, 7: recording coil, 8: upper shield, 9: row bar, 10: coil, 11: chip, 2
0: slider, 21: sliding surface, 22: magnetic recording medium,
23: suspension, 24: magnetic head.

Claims (3)

[Claims] A magnetic field applying means for applying a magnetic field perpendicularly to the magnetoresistive element before being incorporated in the magnetic reproducing head; a means for obtaining a reproduction sensitivity distribution function from the magnetoresistive element; Means for calculating a reproduction track width from a distribution function. 2. The magnetoresistive effect according to claim 1, wherein said magnetic field applying means applies a magnetic field having a width narrow enough to obtain said reproduction sensitivity distribution function to said magnetoresistive effect element. Element reproduction evaluation device. 3. The apparatus according to claim 1, wherein said magnetic field applying means comprises a coil disposed perpendicularly and orthogonally to said magnetoresistive element and a signal applying means for applying a signal to said coil. An apparatus for evaluating reproduction of a magnetoresistive element according to any one of the preceding claims.