JPS58182125A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To apply optimum bias magnetic fields to plural magneto-resistance effect element independently, by adjusting a current for applying the bias magnetic fields at the inside of a head. CONSTITUTION:The magneto-resistance effect element 14 is arranged on a conductor layer 12 as a path for the bias magnetic field current with an insulator layer 13 between. Signal lead-out parts 15 are formed at both ends of the magneto-resistance effect element 14. The serial structures of plural resistors 17 are formed at both ends of the conductor layer 12 for applying the bias magnetic field to the magneto-resistance effect element 14, and plural lead terminal parts 18 are provided between the resistors 17 to constitute lead parts 16, respectively. Consequently, lead lines are connected selectively to one of lead terminal parts 18 to vary the current value of the current for the bias magnetic field stepwise, and even when individual magneto-resistance effect elements 14 have variance in characteristics, an optimum bias point is selected inside of the head.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film magnetic head, particularly a multi-channel magnetic head equipped with a large number of magnetoresistive elements. The present invention relates to a structure for applying a bias magnetic field to a magnetoresistive element of each channel in a four-film magnetic head.

A magnetoresistive element is an element that utilizes a phenomenon in which the resistance value of a magnetic material changes in response to a signal magnetic field, and the rate of change is constant in a constant magnetic field. Therefore, a constant bias magnetic field is generally applied to the signal magnetic field in order to obtain a linear change in resistance value with respect to the 1-magnitude magnetic field. Methods for applying this bias include applying a magnetic field to the magnetoresistive element from the outside using a solid magnet, applying a magnetic field by shunting current to a conductive layer connected in parallel with the magnetoresistive element, and is independent of the magnetoresistive element and the conductor adjacent to the magnetoresistive element.
There is a method in which a turtle layer is provided and a magnetic field caused by a current flowing through the turtle layer is applied to the magnetoresistive element.

The basic configurations of these methods are shown in FIG. 1, FIG. 2, and FIG. 3, respectively. That is, FIG. 1 shows the basic configuration of a method for applying a bias magnetic field to a magnetoresistive element from the outside using a ml magnet.

As shown in the figure, a magnetoresistive confectionery 10 made of a high magnetic permeability magnetic material is provided with lead parts 2 at both ends for signal extraction, and a permanent magnet 2 for applying a bias magnetic field at the rear. It is placed. Figure 2 shows the basic configuration of a method of applying a magnetic field by branching a current to a conductive film arranged in parallel with a magnetoresistive element, in which a conductive layer 4 and a magnetoresistive element 5 are superimposed and Lead portions 6 are provided at both ends of the conductive layer 4 to take out signals, furthermore, to shunt current to the conductor layer 4 and generate a magnetic field. 5
Figure g3 shows the basic structure of a method in which a conductor j- is provided independently of and adjacent to the magnetoresistive element, and a magnetic field caused by a current flowing through it is applied to the magnetoresistive element.

As shown in the figure, the magnetoresistive element 9 is placed on the conductor No. 7 through an insulator 7*8', and lead portions 10 are placed at both ends of the magnetoresistive element 9 for outputting the signal J451. The lead portion 11 is connected to the conductor 7 for applying a bias magnetic field to the effect element 9.
It's not set up.

ヰHere, in the former case, a fixed magnetic field is basically applied to each of the many magnetoresistive elements by the magnetoresistive element configuration, whereas in the latter case, the bias magnetic field is applied to each of the four magnetoresistive elements. The bias magnetic field can be adjusted independently by providing a bias magnetic field corresponding to the magnetic field and adjusting the value of the current flowing therethrough. Therefore, in the independent bias type thin-film magnetoresistive magnetic head, even if there are variations in the magnetic properties of the magnetoresistive element, by optimally selecting the bias point 'ff, the properties can be maximized.

However, an independent bias type magnetic head with such advantages can also be compatible with a large number of magnetic recording and reproducing devices if its bias magnetic field current is adjusted by an external circuit connected to the magnetic head, that is, the magnetic head can be replaced. The disadvantage is that compatibility is compromised.

The present invention solves the above-mentioned problem, and is a model having a structure in which the current flowing through a dedicated unit for applying a bias magnetic field to a plurality of resistance effect elements can be adjusted inside the head. The purpose is to provide an elegant head. This thin-film magnetic head is compatible and can independently apply an optimal bias magnetic field to each magnetoresistive element, which contributes to the characteristics and further improves the magnetic field of each magnetoresistive element. Since it is possible to absorb variations in characteristics, it has the advantage of improving the characteristic yield during manufacturing.

Next, embodiments of the thin film magnetic head of the present invention will be described in terms of mA with reference to the drawings.

FIG. 4 is a perspective view of essential parts of one embodiment, and shows the bias o
(ii) In a thin film magnetic head in which a magnetic material layer serving as a magnetoresistive effect cable is provided by insulating the insulation layer on a conductive layer serving as a path for a field current, the lead portion of the conductive material layer has a plurality of resistors. The current value for the bias magnetic field can be varied step by step by providing a plurality of lead terminals between the resistors and selectively connecting the IJ-door a to the terminals. This is what I did. As shown in the figure, the magnetoresistive effect element 1 is placed on the conductor layer 12 through the intervening body 71113'i.
4 is arranged, and lead portions 15 for signal extraction are provided at both ends of the magnetoresistive element 14. The dedicated layer 12 for applying a bias magnetic field to the magnetoresistive element 14 has f″Lgi at both ends thereof, several resistors 17 are connected in series, and a plurality of leads are connected between the resistors 17. A lead portion 16 provided with a terminal portion 18 is arranged.

In the head having such a configuration, by selectively connecting the lead a (not shown) to one of the plurality of lead terminal portions 18, the bias magnetic field current lIl! 'r: Can be varied in stages, and even if there are variations in the characteristics of individual magnetoresistive cables 14, the structure can be configured so that the characteristics can be maximized by tracing the bias point optimally. , can be done inside the head.

The resistor 17 may be a thin film made of the same material as the conductive layer 12. For example, if titanium is used as this material, its specific resistance is 660c.
m, and can also serve as a suitable resistor. In this case, there is no need to provide an independent process for completely vapor-depositing the resistor, so the process can be simplified.

Next, a thin film magnetic head according to a second embodiment of the present invention will be described with reference to FIG. This implementation row is the resistor of the lead part! - The child part is made of the same material as the material constituting the conductor layer for bias magnetic field, and the lead part is a small width part that becomes a resistor and a large part that becomes a terminal. A magnetoresistive element 21 is formed through the magnetoresistive element 21, and lead portions 22 for taking out the Gogo are provided at both ends of the magnetoresistive element 21, respectively.

Furthermore, the conductor layer 19 for supporting the entire bias magnetic field in the magnetoresistive element 21 has a small width portion 23 that will serve as a plurality of resistors and a large width portion 24 that will serve as a plurality of lead terminal portions. It consists of

By selectively connecting the lead wire to one of the lead terminal portions 24, ff1u of the bias 08 field current flowing through the conductor layer 19 can be varied stepwise. Therefore, even if there are variations in the characteristics of the individual magnetoresistive elements 21, the bias point can be optimally selected for each magnetoresistive element 21, and by adjusting the bias point, the maximum characteristics can be brought out inside the head. Since the resistor and the terminal part can be made of the same material as the material constituting the bias magnetic field four-electric node, the manufacturing process can be greatly simplified.

Titanium or molybdenum is suitable as the material for the conductor for applying a bias magnetic field to the magnetoresistive element. It is desirable that the bias magnetic field forming conductive layer be as thin as possible in order to be able to record and reproduce short wavelength signals. However, if the film thickness becomes too thin, the adjacent film materials will diffuse due to the thermal history received during the manufacturing process, and the resistance will tend to increase. In this respect, titanium or molybdenum is less susceptible to diffusion. In addition, this conductive layer may be configured to contact the recording medium and the flower stand together with a magnetic material having a magnetoresistive effect.
Titanium or molybdenum is also used as a material for the V-coat and conductor layers due to its corrosion resistance.

As described above, the thin-film magnetic head of the present invention has a structure for regulating the subcurrent flowing through the conductor for providing the magnetoresistive element VC bias magnetic field, which is present in many magnetoresistive magnetic heads, inside the head. Because of this, compatibility is unclear when replacing the magnetic heads of many magnetic recording and reproducing devices. Since the optimum bias magnetic field can be applied independently to each magnetoresistive element, the characteristics can be warmed up, and the variation in the magnetic % curvature of each magnetoresistive element can be fully absorbed, so the time It has a good one-year yield.

[Brief explanation of the drawing]

5N, 1, 2 and 3 are respectively perspective views of thin film elements of a conventional thin film magnetic head, and FIGS. FIG. 2 is a perspective view of a thin film element. 12...Conductor layer, 13...Insulator layer,
14... Magnetoresistive element, 16... Lead portion,... Resistor, 24... Lead terminal portion. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2? Figure 2 Figure 3 Figure 4 Figure 6

Claims (4)

[Claims] (1) A magnetoresistive element and a conductor layer for forming a bias magnetic field to be applied to the magnetoresistive element,
The lead part of the conductor has a series structure of multiple e1d resistors, and a plurality of lead terminal parts metal fittings are provided between the resistors, and the lead part has a plurality of lead terminal parts. The electrical conductor, 1
- A thin film magnetic head characterized in that the directivity of the current to be supplied to the magnetic head is made variable in stages. (2) A thin-film magnetic head according to claim 1, wherein the resistor is a thin-film body made of the same material as the conductor layer. (3) The resistor of the lead part and the terminal part are thin film bodies made of the same material as the material in which the conductive layer is formed, and the lead part is a thin film body made of the same material as the material in which the resistor and the terminal part are formed. 2. The thin film magnetic head according to claim 1, wherein the thin film magnetic head is comprised of a portion having a large size and width. (4) Claim 1, 2 or 3, characterized in that the conductive layer is made of titanium or molybdenum.
The thin film magnetic head described in Section 1.