JPH0418778A - Magnetoresistive device - Google Patents

Abstract

PURPOSE:To obtain a magnetoresistive device where a midpoint potential hardly deviates in operation by a method wherein an external resistor is so adjusted as to make an average voltage between an output terminal and an intermediate terminal nearly half as high as a prescribed voltage. CONSTITUTION:Magnetoresistance elements 3 and 4 are formed on an alumina board 2 through evaporation, and a wiring pattern 5, external resistors 6 and 7, an intermediate terminal 8, and output terminals 9 and 10 are printed. In this case, the elements 3 and 4 are so disposed as to enable current flow paths 3a and 4a to extend crossing each other at right angles and connected in series. An intermediate terminal 8 is provided to a connection point 11 of the elements 3 and 4. Furthermore, the resistors 6 and 7 are connected to the elements 3 and 4 in series, and output terminals 9 and 10 are provided to the ends of the resistors 6 and 7 opposite to their ends connected to the elements 3 and 4. Furthermore, the magnetoresistance elements 3 and 4 are covered with a phenolic resin 50.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a ferromagnetic magnetoresistive element (hereinafter referred to as a magnetoresistive element as necessary), and is suitable for use as a position sensor, for example. The present invention relates to a magnetic resistance device.

[Summary of the Invention] The present invention provides a magnetoresistive device used, for example, as a position sensor. An intermediate terminal formed at the connection point of the element, an external resistor connected in series and/or parallel to each magnetoresistive element, and an output terminal formed on the opposite side of the intermediate terminal side of each external resistor. With a predetermined voltage applied between both output terminals, each magnetoresistive element is oriented in a direction substantially perpendicular to the magnetic field and in a direction substantially parallel to the magnetic field in a magnetic field of approximately saturation magnetization or higher. The average voltage between the output terminal and the intermediate terminal before and after changing the arrangement and changing the direction is approximately 1/1/1 of the predetermined voltage.
By adjusting the external resistance so that the voltage becomes 2, the midpoint potential of the magnetoresistive element can be set correctly.

[Prior Art 1] As a magnetoresistive device having a ferromagnetic magnetoresistive element, for example, there is a technology disclosed in Japanese Patent Laid-Open No. 62-293683. This technology integrates a magnetoresistive element block and a printed resistance block, and trims the printed resistance of the printed resistance block to match the magnetoresistive element.
The deviation of the output voltage from the midpoint potential in the child direction and in one direction is made equal.

[Problem to be Solved by the Invention 1] However, in the conventional magnetoresistive device described above, as shown in FIG. If a magnetic field is actually applied to the trimmed magnetoresistive device,
There was a problem that the midpoint potential was off.

In view of this, an object of the present invention is to provide a magnetoresistive device in which the midpoint potential does not shift during actual use.

[Means for Solving the Problems] The magnetoresistive device of the present invention has the following features, for example, as shown in FIGS. Magnetoresistive elements (3), (4) are arranged in such a way that the directions of current paths (3a), (4a) are substantially orthogonal to each other and are connected in series;
) intermediate terminal (8) formed at the connection point (11) of
, external resistors (6), (7) connected in series and/or parallel to the respective magnetoresistive elements (3), (4), and intermediate terminals of the respective external resistors (6), (7) ( 8)
It has output terminals (9) and (10) formed on the opposite side of the side, and when a predetermined voltage is applied between the output terminals (9) and (10), and each magnetoresistive element (3 ), (4
) is placed in a magnetic field at approximately saturation magnetization or higher, with its orientation changed in a direction approximately perpendicular to the magnetic field and a direction approximately parallel to the magnetic field,
The average voltage between the output terminal (9) and the intermediate terminal (8) (or the average voltage between the output terminal (10) and the intermediate terminal (8)) before and after changing the direction is the predetermined voltage /2. The external resistors (6) and (7
) is adjusted.

[Function] Therefore, according to the present invention, the output terminals (9), (10)
With a predetermined voltage applied between the magnetoresistive elements (3) and (4), the respective magnetoresistive elements (3) and (4) are placed in a magnetic field of approximately saturation magnetization or higher, and their orientations are changed in a direction perpendicular to the magnetic field and in a direction parallel to the magnetic field. the output terminals (9) before and after changing the orientation.
) and the intermediate terminal (8) (or the average voltage between the output terminal (10) and the intermediate terminal (8)) is approximately 1/2 of the predetermined voltage. , (7), the average combined resistance value when looking at the magnetoresistive element (3) side from the output terminal (9) and intermediate terminal (8) before and after changing the direction, and the average combined resistance value before and after changing the direction. Output terminal (10) and intermediate terminal (8) at
and the average combined resistance value when looking at the magnetoresistive element (4) side can be made approximately equal to each other.

[Embodiment] Hereinafter, an embodiment of the magnetoresistive device according to the present invention will be described with reference to FIGS. 1 to 7.

In FIG. 1 and FIG. 2, (1) shows the magnetoresistive device in this example, and this magnetoresistive device (1) includes an alumina substrate (2), and on the alumina substrate (2),
Magnetoresistive elements (3), (4) are formed by vapor deposition technology, and wiring patterns (5), external resistors (6), (
7) (hereinafter referred to as a resistor as necessary), intermediate terminal (
8) and output terminals (9) and (10) are formed by printing technology. In this case, the magnetoresistive elements (3), (4
) are arranged so that the directions of the current paths (3a) and (4a), whose directions are shown by solid lines, are substantially perpendicular to each other, and are electrically connected in series. In addition, the connection point (11) between the magnetoresistive elements (3) and (4)
An intermediate terminal (8) is formed at. Sara δko,
The resistance (6L (7) is a magnetoresistive element (3),
(4) in series, and the resistors (6) and (7) have an output terminal (9) on the opposite side of the intermediate terminal (8), respectively.
), (10) are formed. In addition, the magnetoresistive element 7-
(3) and (4) are covered with phenolic resin (50).

FIG. 3 shows the structure of the midpoint potential adjustment jig (12) of the magnetoresistive device (1), and FIG. 4 shows a perspective view taken along the line IV--IV. In Figures 3 and 4,
The midpoint potential adjustment jig (12) includes a jig base (13), and on the jig base (13), a recess (1
4), (15) is formed, and a magnetized magnet (1) is formed as shown in the figure.
7) and (18) are embedded. This magnet (
17), (1B), a substantially uniform magnetic field is generated near the cavity (16) in the direction indicated by the arrow. Note that this uniform magnetic field A is applied to the magnet (
17) and (18) are selected.

Fig. 5 shows the fitting jig (19) of the above-mentioned magnetoresistive device (1) (see Fig. 1).
The four parts (14) of the cavity 16) are attached to the sides of the cavity 19).
), (15) are formed, and a hole (22) for fitting the magnetic resistance bag W(1) is formed.

Next, the operation of the above embodiment will be explained.

First, the hole (2) of the fitting jig (19) shown in FIG.
2), fit the magnetic resistance device (1) shown in Figure 1 into the fitting jig (19) into which the magnetic resistance device (1) is fitted.
) are formed in the cavity (16) of the jig base (13) shown in FIG.
), (15), and magnetoresistive device (1
) is inserted into the cavity (16) (see Fig. 6).

Next, in the state shown in FIG. 6, as shown in FIG. ,(2
4) is bridge-connected and a predetermined voltage V is applied.

A battery (25) is connected between both terminals of the resistors (23) and (24). Here, a voltage measurement terminal (not shown) constituting a laser trimming device (not shown) is connected between the intermediate terminal (26) of the resistors (23) and (24) and the intermediate terminal (8) of the magnetoresistive device (1). ) and measure the voltage between them, V=V. In this case, as understood from FIGS. 6 and 7, the current path (3a) of the magnetoresistive element (3) and the uniform magnetic field A are orthogonal to each other, and the current path (4a) and the uniform magnetic field A becomes parallel.

Next, as shown in the 8th episode, with the fitting jig (19) fitted into the magnetoresistive device (1) rotated approximately 90 degrees clockwise from the direction shown in FIG. Measure. In this case, as understood from FIGS. 7 and 8, the current path (3a) of the magnetoresistive element (3) and the uniform magnetic field A are in a parallel state, and the current path (4a) and the uniform magnetic field A becomes orthogonal.

In this state, the voltage 1 v, l'-I
By trimming the resistor (6) or resistor (7) (so-called function trimming) so that V2 ), that is, the voltage between the output terminal (9) and the intermediate terminal (8) (or the voltage between the output terminal (10) and the intermediate terminal (8)) in the state of FIG. The average voltage between the output terminal (9) and the intermediate terminal (8) (or the voltage between the output terminal (10) and the intermediate terminal (8)) in the state of is the predetermined voltage (2). The voltage will be approximately 1/2 of that.

Therefore, after L-rimming, from the output terminal (9) and the intermediate terminal (8) before (Fig. 6) and after (Fig. 8) the orientation of the magnetoresistive elements (3) and (4) is changed. The average combined resistance value when looking at the magnetoresistive element (3) side, and the magnetoresistive element from the output terminal (10) and intermediate terminal (8) before (Fig. 6) and after (Fig. 8) the direction has been changed. (4) The average combined resistance values when looking at the side are approximately equal to each other.

Note that measuring the voltage between the intermediate terminal (26) and the intermediate terminal (8) without directly measuring the voltage between the output terminal (9) and the intermediate terminal (8), etc. is the measurement before and after changing the direction. This is to increase the rate of change in voltage and reduce the influence of measurement errors.

As mentioned above, according to this embodiment, the magnetoresistive device (1
) The intermediate terminal (26) and the intermediate terminal (8) before and after applying a magnetic field higher than saturation magnetization to the magnetoresistive elements (3) and (4) constituting the magnetic resistance elements (3) and (4) and changing the direction of the magnetic field by 90 degrees.
Connect resistors (6) and (7) so that the voltage between
) is trimmed, it is possible to eliminate a shift in the midpoint potential caused by magnetic hysteresis. Therefore, there is also an advantage that the yield when manufacturing the magnetoresistive element (1) is improved. especially,
Even when the magnetoresistive device is used as a high-precision position sensor, there is no need to select in advance a magnetoresistive element with a small magnetic hysteresis range, and there is an advantage that manufacturing costs are reduced.

FIGS. 9 and 10 show the structure and electrical circuit diagram of another embodiment of the present invention.

In FIGS. 9 and 10, the same components as those shown in FIGS. 1 and 2 are given the same reference numerals.

The magnetoresistive device (101) shown in FIG. 9 replaces the resistors (6) and (7) of the magnetoresistive element (1) shown in FIG. 1 with resistors (106) and (107). ), (4)
are connected in parallel. Therefore, in this embodiment as well, the external circuit is connected in the same way as in FIG. 7, and the resistor (106) and (
107), it is possible to remove the shift in the midpoint potential caused by magnetic hysteresis.

In addition, in the embodiment described in L, the magnetoresistive device (1),
(101) is configured to be rotated by 90 degrees, but the present invention is not limited to this, and magnets 1-(17) and (18) may be rotated by 90 degrees. Furthermore, an electromagnet may be used in place of a pre-magnetized magnetometer (17), (18), that is, a permanent magnet. In addition, by arranging four electromagnets or air-core coils on each side of a square, and arranging current to flow alternately between the electromagnets or air-core coils placed on two opposing sides, the direction of the magnetic field can be automatically adjusted. It may also be rotated 90 degrees.

[Effects of the Invention] According to the present invention, when adjusting the external resistance for adjustment constituting the magnetoresistive device, the adjustment is performed while applying a magnetic field higher than the saturation magnetization to the magnetoresistive element constituting the magnetoresistive device. , the shift in the midpoint potential caused by magnetic hysteresis can be effectively eliminated, and therefore, a magnetoresistive device can be obtained in which the midpoint potential does not shift in actual use.

Note that the present invention is not limited to the above-described embodiments, and it is clear that various changes can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of an embodiment of a magnetoresistive device according to the present invention, FIG. 2 is a circuit diagram of the magnetoresistive device shown in FIG. 1, and FIG. 3 is a plan view of a jig for adjusting the midpoint potential. , Fig. 4 is a perspective view of the jig for adjusting the mid-point potential shown in Fig. 3, showing the cross-section of the cross-section of the cotton, Fig. 5 is a perspective view of the jig for fitting the magnetoresistive device, and Fig. 6 is equivalent to the magnetoresistive device. A plan view showing the state in which a magnetic field is applied, Fig. 7 is a circuit diagram when trimming the external resistor that constitutes the magnetoresistive device, and Fig. 8 shows the magnetoresistive device at 90 degrees with respect to the state shown in Fig. 6. FIG. 9 is a plan view showing a state in which uniform magnetic fields in different directions are applied; FIG. 9 is a perspective view showing the configuration of another embodiment of the magnetoresistive device according to the present invention;
0 is a circuit diagram of the magnetoresistive device shown in FIG. 9, and FIG. 11 is a diagram for explaining the shift in midpoint potential caused by magnetic hysteresis in the prior art. (1) is a magnetoresistive device, (3) and (4) are magnetoresistive elements, (3a) and (4a) are current paths, (6) and (7) are external resistors, (8) is an intermediate terminal, ( 9) and (10) are output terminals.

Claims (1)

[Scope of Claims] Magnetoresistive elements whose current paths are arranged substantially perpendicular to each other and connected in series, an intermediate terminal formed at a connection point between the magnetoresistive elements, and each magnetic resistance element. It has an external resistor connected in series and/or parallel to the element, and an output terminal formed on the opposite side of the intermediate terminal side of each external resistor, and when a predetermined voltage is applied between the two output terminals. , and each magnetoresistive element is placed in a magnetic field of approximately saturation magnetization or higher with its orientation changed in a direction approximately perpendicular to the magnetic field and in a direction approximately parallel to the magnetic field, and between the output terminal and the intermediate terminal before and after changing the orientation. The average voltage at is approximately 1/2 of the predetermined voltage.
A magnetoresistive device characterized in that the external resistor is adjusted so that the voltage becomes .