JPS592089B2 - Tasoshijiki head - Google Patents

Description

Detailed Description of the Invention The present invention provides a bias line in a multi-element magnetic head having a plurality of magnetoresistive elements by coating a ferromagnetic thin plate or thin film such as permalloy on a ferrite or other ferromagnetic substrate. Alternatively, the present invention relates to a structure that prevents a magnetoresistive element from having a step and being easily disconnected when a common electrode is added.

Conventionally, the basic structure of a magnetic head that utilizes the magnetoresistive effect, in which the electrical resistance value changes when a magnetic field is applied to a ferromagnetic material, is as shown in FIG. In FIG. 1, recording medium 1
A magnetoresistive element 2 made of a ferromagnetic thin plate is brought into contact perpendicularly (in the y direction) to the recording medium 1 so as to be able to slide on the recording medium 1. Electrodes 3 and 4 are provided at both ends of the magnetoresistive element 2 in the longitudinal direction (two directions).
A constant current is passed between the electrodes 3 and 4, and a change in resistance value in the z direction is detected by a change in voltage between the electrodes 3 and 4 using a signal magnetic field in the y direction from the recording medium 1. When a multi-element magnetic head is constructed using this method, the structure shown in FIG. 2 is obtained. A ferromagnetic conductive film having anisotropy such as permalloy is formed on a non-magnetic insulating substrate 5 such as glass so that the axis of easy magnetization is in the direction of arrow a. Electrodes 3 and 4 are provided at both ends of the magnetoresistive element 2, and the voltage between the electrodes 3 and 4 is detected. The recording medium contacts and slides on the sliding surface 6 of the substrate 5. In this method, the signal magnetic field strength from the recording medium 1 decreases exponentially, and especially in the region where the recording wavelength on the recording medium is short, the attenuation of the signal magnetic field in the width direction of the magnetoresistive element 2 is extremely large. becomes. In addition, in this head configuration, if the width W corresponding to the head track width is made extremely small, the output voltage will decrease, and it is also possible to reduce the width U of the element 2 and increase the current density to increase the output voltage. However, as the track pitch becomes denser, there are many problems in manufacturing, and the wear resistance is also poor, making it difficult in practice. In view of the above-mentioned conventional example, the present invention has been developed in a multi-element magnetic head by guiding magnetic flux to the magnetoresistive element using a magnetic flux convergence core so as to prevent the magnetoresistive element (hereinafter referred to as MR element) from sliding in direct contact with the recording medium. In addition to increasing the efficiency of the resistance effect element and improving its wear characteristics, by providing grooves in the ferromagnetic substrate, it is possible to configure the magnetoresistive effect element perpendicular to the recording medium, which is more effective than conventional methods. In addition to making it possible to obtain a dense head pitch, a coil for generating a bias magnetic field is buried in a groove provided in the ferromagnetic substrate, and a bias magnetic field is applied to all elements in common to obtain a reproduction output without distortion. MR who seduces Mizogami
This prevents the occurrence of disconnection of the MR element by preventing a step from forming in the element.

FIG. 3 shows a plan view of a multi-element magnetic head according to the present invention, FIG. 4 shows a sectional view taken along line AN, and FIG. 5 shows a sectional view taken along line B'.

A groove 8 is provided in the ferromagnetic substrate 7, and a non-magnetic conductive layer 9 of relatively high melting point, such as copper or gold, is formed in the groove 8 using a method such as vapor deposition, or a wire-like conductive layer 9 is formed using a method such as vapor deposition. A non-magnetic conductor 9 is buried in the groove 8 and filled with a non-magnetic insulating material 10 such as glass. In this case, the non-magnetic insulating material 10 is formed in a U-shape, and as shown in FIG. 5, exposed portions for the non-magnetic conductor 9 to be connected to an external circuit are provided at both ends of the U-shape.
Although the shape of the groove 8 is shown as a circular arc in FIG. 4, it may have any other shape as long as it can be constructed so that no ferromagnetic material directly opposes the magnetoresistive element. The surface of the substrate 7 having the grooves 8 is polished so that there are no irregularities at the interface between the non-magnetic insulating material 10 and the substrate 7. When the ferromagnetic substrate 7 is made of ceramic such as ferrite, it has a relatively high resistance.
There is no problem even if a conductor such as aluminum or permalloy is directly formed on the substrate 7 by means such as vapor deposition. Further, it is not possible to directly provide a conductive layer on the substrate 7 using a conductive ferromagnetic material such as Perlloy, and electrical insulation is required on the surfaces of the substrate 7 and the non-magnetic insulating material 10. The electrical insulating film is S
IO or SlO2 can be formed using means such as vapor deposition. Next, a signal detection coil 13 is deposited on each element perpendicularly to the groove, and a film of a conductive material such as aluminum or copper is deposited in parallel to each MR element using a method such as vapor deposition. Using photo-etching, electron beam processing technology, etc., it is formed into a shape that encompasses the MR element, as shown in FIG. Contact surface 1 of this coil 13 with the recording medium
An electrical insulating layer 14 of SiO, SiO2 or the like is provided on the parts other than the part closest to coil 6 and the parts of coils 9 and 13 farthest from the contact point using vapor deposition or sputtering technology. Next, a ferromagnetic film is provided on this insulating layer 14 using vapor deposition or sputtering technology, so that the axis of easy magnetization is aligned in the width direction of the MR element 11, that is, in a direction parallel to the groove 8. Form it so that it becomes. It is effective that the length of the MR element 11 spans the entire width S of the groove 8. At the same time as the MR element 11, magnetic flux converging cores 12 with high magnetic permeability are provided between the groove 8 and the abutting surface 16 of the recording medium, and in the direction away from the recording medium with respect to the groove 8. The magnetic flux converging core 12 forms a gap with the substrate 7 on the side of the recording medium abutting surface 16 of the substrate 7. Magnetic flux convergence core 12
A portion far from the contact surface 16 with the recording medium is electrically connected to a common electrode 15 provided commonly to all elements. For the common electrode 15, a new conductive layer of aluminum, copper, etc. is provided, or the shape of the magnetic flux converging core 12 itself is formed so as to have a common electrode. The magnetic head according to the present invention is a multi-channel head made especially for reproducing recorded signals, and operates by detecting the voltage induced across the MR element 11.

The signal magnetic field generated from the recording medium is guided through the magnetic gap 13 between the ferromagnetic substrate 7 and the magnetic flux convergence core 12, and is applied to both ends of the MR element near the contact surface 16 with the recording medium. , a magnetic potential is applied.On the other hand, the MR element 11 is passed through the coil 13 provided for each element,
A constant current is passed between the common electrodes 15 that are in electrical contact with the convergent core 12, and the difference in level between the coil 13 and the electrodes 15 is taken out as a signal.When the signal magnetic field changes, the MR
The magnetic potentials induced at both ends of the element change, the resistance value of the MR element changes, the potential difference generated between the coil 13 and the electrode 15 changes, and the recorded signal can be read out. Figure 6 shows the characteristics of resistivity change △ρ/ρ with respect to the magnetic field H of permalloy, and the input signal magnetic field 111
1 and an output voltage 1010 when the resulting resistance change is extracted as a voltage.

The magnetoresistive effect of permalloy becomes noticeable near the magnetic field where rotating magnetization begins to appear, and when the rotation of magnetization is completed and saturation is reached, the rate of change in resistance also becomes saturated. When a signal magnetic field 11 is applied to this magnetoresistive element with no bias, the output voltage 10 becomes frequency doubled, as can be easily understood from the fact that the curve of the magnetoresistive effect becomes symmetrical with respect to the vertical axis. Also, since the characteristics of the nonlinear part are used, the distortion of the output waveform is large. On the other hand, if a bias is applied to the magnetoresistive element by the bias coil 9 according to the present invention, and the bias is moved from point B to point C in an unbiased state, and a signal magnetic field 11 is applied, the magnetoresistive effect curve has good linearity. The output waveform has the same frequency as the input signal and has less distortion, allowing good reproduction. Since this coil is provided in a magnetic circuit having a gap, it can also be used as a demagnetizing coil. As described above, the magnetic head of the present invention is designed so that the plane on which the MR element 11 is formed is smooth.

That is, the film thickness of the MR element 11 is generally considered to be about 500 angstroms to 2 microns, the film thickness of the bias coil 9 is about 1 micron, and the film thickness of the MR element 11 and the bias coil 9 is about 1 micron. If a step occurs, the MR element is easily disconnected. That is, when a bias filter is formed on a substrate, disconnection of the MR element always becomes a major manufacturing problem. Therefore, as in this embodiment, the current supply coil 13 is uniformly formed on the flush substrate 7 in which the bias coil 9 is embedded by means such as vapor deposition, and the MR element 11 and the magnetic flux convergence core are If photoetching is carried out to a shape that encompasses the MR element 12 to a greater extent, there will be no step difference at the MR element 11 and no disconnection will occur. In addition, the multi-element magnetic head according to the present invention has the following effects.

In other words, by providing an MR element perpendicular to the groove on a substrate having grooves common to all elements and parallel to the recording medium, the conventional problem, that is, the track width of the MR element, can be solved. This improves the problem that it was difficult to increase the density of the element and increase the recording density because the width W cannot be made extremely small. Also,
By arranging the MR elements perpendicular to the contact sliding surface, it is possible to configure a common electrode, and the electrode required for each element in the conventional example can be reduced to one for each element, making it possible to create a more densely packed structure. The elements can be placed in the
In addition, in order to induce magnetic flux by a magnetic flux convergence core, MR
MR due to wear and tear due to the element not sliding in direct contact with the recording medium
There was no longer any deterioration in characteristics. Additionally, a bias coil common to all elements applies a bias magnetic field, making it possible to obtain an output signal with less distortion.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a magnetic head using a conventional magnetoresistive element, Fig. 2 is a block diagram of a multi-element magnetic head constructed using the principle magnetic head of Fig. 1, and Fig. 3 is a diagram of the present invention. A plan view of one embodiment of the magnetic head according to the invention, FIG. 4 is a sectional view taken along the line A-N in FIG. 3, FIG.
The figure is an explanatory diagram of the magnetoresistive effect and the bias effect. 7...Ferromagnetic substrate, 8-...Groove, 9-
......Nonmagnetic conductor layer, 10...Nonmagnetic insulating material, 11...MR element, 12...
・Magnetic flux convergence core, 13... Coil 14...
...Insulator layer, 15...Common electrode, 16...
...Abutment surface.

Claims (1)

[Claims] 1 On one side of the ferromagnetic substrate perpendicular to the recording medium contact surface,
A groove is provided parallel to the recording medium contact surface, a nonmagnetic conductive layer for a bias coil is disposed in the groove, the groove is filled with a nonmagnetic insulating material to flatten it, and the groove is bridged. a plurality of magnetoresistive elements are disposed in the magnetoresistive element, a magnetic flux convergence core having a gap with the ferromagnetic substrate is provided at least at one end of the magnetoresistive element on the recording medium contacting surface side, and the non-magnetic A multi-element magnetic head characterized in that a conductive layer is common to a plurality of magnetoresistive elements.