JPS6295711A - Composite thin film magnetic head and its reproducing drive method - Google Patents

Abstract

PURPOSE:To obtain a reproduced output while noise is suppressed and to reduce number of terminals by connecting a thin film coil clipped by upper and lower soft magnetic layers and whose resistance for forming the composite thin film magnetic head is nearly equal and the magneto-resistance element as required and amplifying the output of the both differentially. CONSTITUTION:The upper/lower soft magnetic layers 6, 7, a thin film coil 8 clipped by the layers 6, 7 and the magneto-resistance element 9 whose electric resistance is nearly equal to that of the coil 8 constitute the composite thin film magnetic head having a gap 13. Each end of the element 9 and the coil 8 is connected respectively and connected to ground as a common terminal, a reproduced output is subject to differential amplifier processing via each other end of the element 9 and the coil 8 to cancel the noise component. Thus, number of terminals is reduced into 3 and the reproduced output is obtained while noise is suppressed.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is a composite thin-film magnetic head with a thin-film inductive head and a magnetoresistive head with a small number of terminals, which can obtain a high reproduction output voltage with low noise. It is related to the head.

(Prior Art) Magnetoresistive heads (hereinafter referred to as MR heads) have been in the spotlight in order to increase the density and reduce the size of magnetic file devices. An MR head uses an MR element whose resistance value changes depending on the angle formed between the direction of current and the direction of magnetization, and extracts changes in a signal magnetic field as changes in resistance. Therefore,
The reproduction output voltage, which is the product of the sense current and the resistance change, does not depend on the relative speed of the medium and head, and if the bias level is set appropriately, it is possible to obtain a large reproduction output voltage proportional to the sense current. can.

Since the MR head is a read-only head, a composite thin-film magnetic head that uses an inductive thin-film head for recording and integrates a recording and reproducing head is being studied. Conventionally, all recording and reproducing functions were shared between the dual-type head and the MR head. In other words, the inductive head is used only for recording, and the KFiM head is used only for recording.
Only the output from the R head was being produced.

(Problems to be Solved by the Invention) It is desirable for the MR head to have a three-terminal configuration in order to reduce various noises. This is because, in order to prevent resistance changes due to temperature changes in the MR element from being superimposed on the reproduced output as noise, K is divided into two equal parts and biased so that the reproduced outputs of opposite phases are obtained from each of the MR elements. It is necessary to set all levels and fully differentially amplify the two playback outputs.

In addition, in the MR head, it is necessary to supply the entire sense current, which generates a DC voltage across the MR element, and with two terminals, it is difficult to extract the reproduced output using balanced signal lines, which eliminates the influence of external noise. For this reason, it is necessary to use a three-terminal configuration and output 10 reproduction outputs using balanced signal lines.

However, when the MR head has a three-terminal configuration, the number of terminals including the recording inductive tip head becomes four terminals even if one terminal is fully integrated. As the number of terminals increases in this way, the number of cables and contacts that connect the magnetic head and the electrical circuit increases, which may cause a decrease in reliability.Especially in the case of a multi-track thin-film magnetic head, the number of cables increases. This increase is a serious problem in implementation.

An object of the present invention is to reduce the number of terminals to three and provide a structure of an FC composite thin film magnetic head and a method for driving the same.

(Friendly Means for Solving Problems) The gist of the present invention is that a spiral thin film coil each having two terminals and an MR element are sandwiched between upper and lower soft magnetic layers, and the MR element is sandwiched between upper and lower soft magnetic layers. This is a composite thin-film magnetic head with a structure in which a gap is formed between the upper and lower soft magnetic layers of the thin-film coil and the MR element. This is a composite thin-film magnetic head that has approximately the same values.

As a method of driving this composite thin-film magnetic head during reproduction, the common terminal of the thin-film coil and the MR element is grounded, and an equal constant current is supplied from the other terminal of each.
A method of differentially amplifying the voltage generated between two terminals to which a constant current is applied.The common terminal of the thin film coil and the M'R element is grounded, and a constant voltage is supplied through a resistor equal to the other terminal. At the same time, there is a method for differentially amplifying the voltage generated between the terminals connected to the resistor, and a method for grounding the common terminal of the thin film coil and the MR element so that the thin film coil and the MR element each serve as an emitter load. There is a method of differentially amplifying the voltage generated between the collectors of a common-base transistor amplifier.

(Function) Since the actance of the thin film coil is very small, the impedance when looking from the common terminal of the thin film coil and the MR element to the other terminal is only a resistor.

Since the resistances of the thin film coil and the MR element are equal, the impedances of the two terminals for outputting the reproduced output with respect to the ground terminal are also equal, and it is possible to use a signal line of the balance type. Therefore, the influence of external noise can be reduced.

Furthermore, in a composite thin film head, the thin film coil and the MR element are arranged very close to each other using fine pattern fabrication technology. Therefore, since both are kept at almost the same temperature, only the difference in temperature coefficient of resistance becomes noise, but the noise due to changes in temperature jF is significantly lower than when using a two-terminal MR element alone. can be reduced.

In this way, the number of terminals is at least three, and M
Not only can you obtain the same function as the R element, but also the M element.
It is also possible to obtain a thicker output by adding the reproduction outputs of the R element and the thin film inductive head.

FIGS. 2(a) and 2(b) respectively show the reproduction output waveforms of the thin film inductance head and the MR head for the magnetization pattern recorded on the medium, and the corresponding recording medium. 3 is the recording magnetization, 3 is the magnetic flux detected by the MR head, 4 is the magnetic flux detected by the thin film inductive head, and 5 is the differential waveform of the magnetic flux 4 detected by the thin film inductive head. In FIG. 2, the MR head operates as a shielded MR head, and detects perpendicular magnetic flux 3 from the medium 1 on the transition region of the recorded magnetization 2 of the medium 1. The MR head is a magnetic flux detection type head, and the reproduced output waveform has the same phase as the detected magnetic flux 3 in the perpendicular direction.

On the other hand, the thin film inductor tape head detects an in-plane magnetic flux 4 which becomes O at the maximum transition region at the center of the recorded magnetization 2 of the medium 1. The thin film inductive head is a magnetic flux differential type head, and the reproduced output waveform is a differential waveform 5 of the detected magnetic flux 4 in the in-plane direction. Therefore, in Figure 2,
The reproduction output waveform of the MR head is similar to the vertical magnetic flux 3, and the reproduction output waveform of the thin film inductive head is similar to the differential waveform 5 of the in-plane magnetic flux 4.
The peaks of the reproduction output waveforms of the head and the thin-film inductive head coincide, and it is possible to obtain a larger reproduction output than when each is used alone.

Here, it is not necessary to make the absolute value of the reproduction output voltage of the thin film inductor and the MR head coincide.

By combining the reproduction outputs of the thin-film inductive head and the MR head, the purpose is to suppress noise caused by temperature changes and external noise, and the reproduction outputs of each are simply added together. be. In the case of Fig. 2, the polarity of the reproduced output waveform of the MR head and the polarity of the reproduced output waveform of the thin film inductive head are opposite to each other.
By biasing the R head and performing differential amplification, only noise is suppressed, and a reproduced output with a good signal-to-noise ratio can be obtained.

(Example) FIGS. 1(a) and 1(b) are a plan view and a cross-sectional view of a composite thin-film magnetic head according to the present invention, and 6! 'i upper soft magnetic layer, 7 lower soft magnetic layer, 8 thin film coil, 9 M
R element, IO is Ml (terminal of the element, 11 is a terminal of the thin film coil, 12 is a common terminal, 13 is a gap.

The manufacturing procedure of the composite thin film magnetic head shown in FIG. 1 will be described.

First, a 10 μm thick Al2O underlayer was placed on the Cerahac substrate.
Sputtered and precision polished. Next, a permalloy film that is similar to the lower magnetic layer 7 is sputtered to a thickness of 3 μm, and patterned using photolithography as shown in FIG.
In order to flatten the step caused by the lower soft magnetic layer 7, the photosensitive organic film is patterned and annealed, and then an MR film 400 made of permalloy and a shunt film 2 made of X1Ti are formed.
00 large, soft film zsoit made from permalloy
- Films were formed by sequential vapor deposition, and an MR element 9 was manufactured using photophosphorography technology. A 2tlnL film was formed using a thin film coil 8t made of Cu using a frame plating method, and at the same time, lead wires for the MR element 9 were also fabricated. After flattening the step caused by the thin film coil 8 using a photosensitive organic film, a 3 μm thick upper soft magnetic layer 6 made of permalloy was formed by sputtering and patterned using photolithography technology.

In order to define the gap 13, a 0.2 μm AltOs film was sputtered before and after producing the MR element 9.

Finally, each terminal 1 of the MR element 9 and thin film coil 8
0.11 and the common terminal 12 by electroplating.
25 μm plating with Al and O as protective layers.

was sputtered to a thickness of 20 μm to complete a trans-G-Sara. The manufactured transducer was cut, polished, and formed into a floating head.

In this head manufacturing procedure, the upper and lower soft magnetic layers 6
In addition to permalloy, the materials of 7 are permalloy, Sendas),
Any soft magnetic material with high saturation magnetization and magnetic permeability, such as a CoZrNb amorphous film, can be used, and manufacturing methods include sputtering, plating, and vapor deposition. Further, in this embodiment, as the MR element 9, a shunt film and a soft film are laminated on the MR film, and a bias magnetic field generated by magnetizing the soft film gives a bias to the MR element 9. It is also possible to use a shunt bias in which only a shunt film is laminated on the film, or a barber pole bias in which Au stripes are diagonally arranged on the MR film.

In the composite thin film magnetic head having the structure shown in FIG.
When the track width is 15 μm and the number of turns of the thin film coil is 8 turns, the resistance value of the MR element 9 and the thin film coil 8 is approximately 15.
It was equal to Ω. If the track width differs and the resistance value of the MR element 9 changes, the resistance values of both can be made equal by adjusting the thickness of the thin film coil 8.

FIG. 3 is a block diagram showing an example of a method for driving the composite thin film magnetic head of the present invention during reproduction. MR element 9
A common terminal of the thin film coil 8 and the thin film coil 8 was grounded, and current sources 14 and 15 were connected to the other terminal, respectively. When a current is supplied from the current source 14 to the MR element 9, a rightward bias magnetic field is applied to the MR element 9 in FIG. 1(b). Therefore, for the magnetic flux flowing in the direction from the medium to the MR element 9,
The resistance value of MR element 9 decreased. On the other hand, the lower soft magnetic layer 7 t-17-ding side with respect to the traveling direction of the medium,
If the upper soft magnetic layer 6 is on the trailing side, the MR element 9
The direction of the magnetic flux passing through the upper and lower soft magnetic layers 6 and 7 before and after the magnetic flux from the medium flows in is from counterclockwise to clockwise in FIG. 1(b).

Therefore, an AC positive voltage was induced between the terminals 11 and 12. Since a constant current is supplied to the MR element 9,
Due to the decrease in resistance, a negative AC voltage is induced between terminals 10 and 12, and when the voltage between terminals 10 and 11 is differentially amplified, the outputs of the MR head and the thin film inductive head can be added. did it. At this time, since the resistance values of the MR element 9 and the thin film coil 8 are almost equal, the terminal 10-1
The DC voltage between the terminals 2 and 11 and the DC voltage between the terminals 11 and 12 were approximately equal, and even if the amplifier 16 was directly connected, the output of the amplifier 16 did not become saturated. In addition, noise caused by temperature changes in the MR element 9 and the thin film coil 8 and external noise are added in the same phase, and can be significantly suppressed.

FIG. 4 is a block diagram showing another example of driving the composite thin film magnetic head of the present invention during full reproduction.

A common terminal of the MR element 9 and the thin film coil 8 was grounded, and a constant positive voltage was supplied to the other terminal through resistors 17 and 18i, respectively. The current flowing through the MR element 9 biases the MR element 9 in the same direction as in the embodiment shown in FIG. With respect to the magnetic flux flowing into the MR element 9 from the medium, the resistance value of the MR element 9 decreases and the current flowing through the resistor 17 increases, so that the terminal 10-1 in FIG. 1(b)
A negative AC voltage was induced between the two. On the other hand, a positive AC voltage is induced between terminals 11 and 12, similar to the Tomomi flow side shown in FIG. I was able to get the play output money.

FIG. 5 is a block diagram showing another example of driving the composite thin film magnetic head of the present invention during reproduction.

The MR element 9 and thin film coil 8 are each connected as an emitter load of a common base transistor amplifier, and the MR element 9 and the thin film coil 8 are connected as emitter loads of a common base transistor amplifier.
A negative voltage is applied to the common terminal of the thin-film coil 8 and a positive voltage is applied to the collector of the transistor through a resistor 20 and 21. The base of the transistor was grounded. The emitter current of the transistor biases the KMR element 9 in the same direction as the Tomomi flow side shown in FIG. 3, fc. MR element 9 from the medium! /c For the magnetic flux in the direction of inflow, MR
The resistance value of element 9 decreased, the emitter current of the transistor increased, and the voltage drop across resistor 20 increased. On the other hand, a negative AC voltage was induced between the terminals of the thin film coil, the emitter current of the transistor decreased, and the voltage drop across the resistor 21 decreased. Therefore, by performing differential amplification in the amplifier 16, the signal components are added and a reproduced output with suppressed noise components can be produced.

It goes without saying that during recording, by passing a recording current through the thin film coil 8, the magnetic field generated from the gap 13 can perform the recording operation in the same way as a normal magnetic head.

(Effects of the Invention) As described above, by using the composite thin film magnetic head of the present invention and its driving method, it is possible to not only obtain a composite thin film magnetic head with a small number of terminals, but also to add signals and reduce noise. Since it is possible to bring out the suppressed playback output,
A highly reliable high-density magnetic dual device can be obtained by utilizing the floating head alone as a floppy disk head or a floating tape device head.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a plan view and a sectional view showing an example of a composite thin film magnetic head according to the present invention, and FIG.
). (b) is a diagram showing reproduction output waveforms of a thin film inductive head and an MR head and a magnetic medium with respect to a magnetization pattern recorded on the medium, FIGS. 3 and 4; FIG. FIG. 5 is a block diagram showing a method for driving a composite thin film magnetic head according to the present invention, in which 1...medium, 2...recording magnetization, 3...magnetic flux detected by the MR head, 4... Magnetic flux detected by the thin film inductive head, 5... 4 differential waveform, 6... Upper soft magnetic layer, 7... Lower soft magnetic layer, 8... Thin film coil, 9... MR element, 10...
・Terminal of MR element, 11...Terminal of thin film coil, 12
...Common terminal, 13...Gap, 14.15...
・Current source, 16...Amplifier, 17, 18, 20.21
...Resistance, 19... Voltage source. Representative Patent Attorney 1 Susumu Hara 71-1 Figure 2 Figure 1. Medium 2, recording magnetization 3, magnetic flux 4 detected by the MR bed, magnetic flux 5 detected by the thin film inductive head, differential waveform of magnetic flux 4 Fig. 3 71-4

Claims (4)

[Claims] (1) A spiral thin-film coil and a magnetoresistive element each having two terminals are sandwiched between upper and lower soft magnetic layers, and an interval between the upper and lower soft magnetic layers sandwiching the magnetoresistive element. In a composite thin film magnetic head having a structure in which a gap is formed with respect to a recording medium, one terminal of the thin film coil and one terminal of the magnetoresistive element are common, and the resistance of the thin film coil and the magnetoresistive element are in common. A composite thin-film magnetic head characterized in that the resistance of the effect elements is almost equal. (2) A spiral thin film coil and a magnetoresistive element each having two terminals are sandwiched between upper and lower soft magnetic layers, and an interval between the upper and lower soft magnetic layers sandwiching the magnetoresistive element. In a composite thin film magnetic head having a structure in which a gap is formed with respect to a recording medium, one terminal of the thin film coil and one terminal of the magnetoresistive element are common, and the resistance of the thin film coil and the magnetoresistive element are in common. The resistances of the effect elements are approximately equal. A reproduction driving method for a composite thin film magnetic head, wherein the common terminal is grounded during reproduction, and an equal amount of constant is applied from the other terminal of each of the thin film coil and the magnetoresistive element. A reproduction driving method for a composite thin-film magnetic head, characterized in that a current is supplied and a voltage generated between two terminals to which a constant current is applied is differentially amplified. (3) A spiral thin film coil and a magnetoresistive element each having two terminals are sandwiched between upper and lower soft magnetic layers, and an interval between the upper and lower soft magnetic layers sandwiching the magnetoresistive element. In a composite thin film magnetic head having a structure in which a gap is formed with respect to a recording medium, one terminal of the thin film coil and one terminal of the magnetoresistive element are common, and the resistance of the thin film coil and the magnetoresistive element are in common. A reproduction driving method for a composite thin film magnetic head characterized in that the resistances of the effect elements are approximately equal, wherein the common terminal is grounded during reproduction, and the other terminal of each of the thin film coil and the magnetoresistive element is grounded. A composite thin film magnetic head reproducing method characterized in that a constant voltage is supplied through resistors of equal size and a voltage generated between terminals connected to the resistors is differentially amplified. (4) A spiral thin-film coil and a magnetoresistive element each having two terminals are sandwiched between upper and lower soft magnetic layers, and an interval between the upper and lower soft magnetic layers sandwiching the magnetoresistive element. In a composite thin film magnetic head having a structure in which a gap is formed with respect to a recording medium, one terminal of the thin film coil and one terminal of the magnetoresistive element are common, and the resistance of the thin film coil and the magnetoresistive element are in common. A reproduction driving method for a composite thin film magnetic head characterized in that the resistances of the effect elements are approximately equal, wherein the common terminal is grounded during reproduction, and the thin film coil and the magnetoresistive element are connected to a common base transistor amplifier. A composite thin film magnetic head reproducing method characterized in that the composite thin film magnetic head is connected to each of the two amplifiers so as to serve as an emitter load, and the voltage generated between the collectors of the amplifiers is differentially amplified.