JPH04369278A - Ferromagnetic magnetoresistance element with full bridge structure - Google Patents

Abstract

PURPOSE:To obtain a ferromagnetic magnetoresistance element of a full bridge structure in which a large output voltage is obtained, and a high accuracy detection is performed without necessity of special temperature characteristic correcting means. CONSTITUTION:First to fourth magnetoresistance units MR1-MR4 are formed of ferromagnetic magnetoresistance materials, and connected in series to form a full bridge. The opposed first and third units MR1 and MR3 have equal resistance value change in the case of a magnetic flux variation. The opposed second and fourth units MR2 and MR4 have equal resistance value change in the case of a magnetic flux variation. Further, the adjacent first (third unit MR3) and second (fourth unit MR4 units MR2) have reverse change of the resistance value change in the case of the magnetic flux variation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic magnetoresistive element having a full bridge structure made of a magnetoresistive material made of a ferromagnetic magnetoresistive material.

0002

2. Description of the Related Art FIG. 8 is a circuit diagram schematically showing a conventional full-bridge structure ferromagnetic magnetoresistive element. The conventional ferromagnetic magnetoresistive element 1 has first and second magnetoresistive elements MR1 and MR2 made of a ferromagnetic magnetoresistive material and thick film resistors R1 and R2 made of a resistance material connected in series. are connected to form a full bridge. Here, the connection point between the first magnetoresistive element MR1 and the thick film resistor R1 is
The input terminal T1 is the connection point between the second magnetoresistive element MR2 and the thick film resistor R2, and the connection point between the first magnetoresistive element MR1 and the second magnetoresistive element MR2 is the first output terminal. A terminal T3 is defined as a second output terminal T4, and a connection point between the thick film resistor R1 and the thick film resistor R2 is defined as a second output terminal T4. Also, the first and second
The magnetoresistive elements MR1 and MR2 are arranged so that their respective magnetoresistive patterns are orthogonal to each other, and exhibit resistance changes that are opposite to each other with respect to changes in magnetic flux that cross the ferromagnetic magnetoresistive elements.

Next, the operation of the conventional ferromagnetic magnetoresistive element will be explained based on FIGS. 9 and 10(a) and (b). As shown in FIG. 9, for example, a magnet 2 is placed near the conventional ferromagnetic magnetoresistive element 1, and as the magnet 2 rotates in the direction of arrow A, the direction of magnetic flux crossing the ferromagnetic magnetoresistive element 1 changes. First, the first input terminal T1 is set to Vcc,
When the second input terminal T2 is connected to GND and a desired voltage is input to the full bridge, the voltage value divided by the resistance between the first magnetoresistive element MR1 and the second magnetoresistive element MR2 is displayed at the first output terminal T3. is output, and a voltage value resistance-divided by the thick film resistor R1 and the thick film resistor R2 is output to the second output terminal T4.

[0004] Next, when the direction of the magnetic flux crossing the ferromagnetic magnetoresistive element 1 changes as the magnet 2 rotates, the first magnetoresistive element MR1 and the second magnetoresistive element MR2 exhibit opposite resistance changes. Therefore, a sinusoidal voltage waveform as shown by B in FIG. 10(a) is output to the first output terminal T3, and the thick film resistors R1,
Since R2 does not show a change in resistance value with respect to a change in magnetic flux, a voltage waveform having a constant value as shown by B in FIG. 10(a) is output to the second output terminal T4. Here, if we take the difference between the first output terminal T3 and the second output terminal T4, we can see that FIG.
As shown in (b) of FIG. 10, an output waveform having the same amplitude and the same period as the voltage waveform B in FIG. 10(a) is obtained, and the rotation angle of the magnet 2 is detected from this output voltage value.

[0005]

[Problems to be Solved by the Invention] As described above, the conventional ferromagnetic magnetoresistive element has the first and second magnetoresistive elements MR1.
, MR2 and the thick film resistors R1 and R2 constitute a full bridge, so there was a problem that the amplitude of the output voltage was small. In addition, the first and second magnetoresistive elements MR1, M
Since the temperature characteristics of the resistance values of R2 and the thick film resistors R1 and R2 are different, the output voltage includes the influence of the environmental temperature.
There is also the problem that the rotation angle of the magnet 2 cannot be accurately detected, and in order to improve the detection accuracy, a temperature characteristic correction means is required.

The present invention was made in order to solve the above-mentioned problems, and provides a ferromagnetic magnetoresistive element that can provide a large output voltage and can detect with high precision without the need for special correction means for temperature characteristics. The purpose is to obtain.

[0007]

[Means for Solving the Problems] A ferromagnetic magnetoresistive element according to the present invention connects four magnetoresistive bodies made of ferromagnetic magnetoresistive material in series, and connects a pair of diagonally opposing connection points to input terminals. Then, a full bridge is formed with the other pair of diagonally facing connection points as output terminals, and the change in resistance value with respect to the change in magnetic flux between the opposing magnetoresistive elements is the same, and the change in resistance value between the opposing magnetoresistive elements is the same. The change in resistance value with respect to the change in magnetic flux is the opposite change in resistance value.

[0008]

[Operation] In the invention configured as described above, since the four magnetoresistive elements constituting the full bridge are made of ferromagnetic magnetoresistive material, these magnetoresistive elements are subject to changes in resistance value due to environmental temperature. In other words, the temperature characteristics are the same, and by taking the difference between the pair of output terminals, an output voltage from which the influence of the temperature characteristics has been removed can be obtained.

[0009]Furthermore, since the changes in resistance value due to changes in magnetic flux between adjacent magnetoresistive elements show opposite changes in resistance value, and the changes in resistance value due to changes in magnetic flux between opposing magnetoresistive elements show the same change in resistance value, Output waveforms with opposite phases are obtained from each of the pair of output terminals, and by taking the difference between these output terminals, an output waveform with twice the amplitude is obtained.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. Example 1. FIG. 1 is a circuit diagram schematically showing a first embodiment of the present invention. In the ferromagnetic magnetoresistive element 3 of Example 1, the four first to fourth magnetoresistive elements MR1, MR2, MR3, and MR4 made of ferromagnetic magnetoresistive material are connected in series to form a full bridge. There is. Here, the opposing first magnetoresistive element MR1 and the third magnetoresistive element MR3 show the same change in resistance value with respect to a change in magnetic flux, and the opposing second magnetic resistance element MR2 and the fourth magnetic resistance element MR4 exhibit the same change in resistance value with respect to a change in magnetic flux. shows the same change in resistance value with respect to a change in magnetic flux, and the adjacent first magnetoresistive element MR1 (third magnetoresistive element MR3) and second magnetoresistive element MR2 (fourth magnetoresistive element MR4) It is configured to show a change in resistance value that is opposite to the change in resistance value.

Next, the operation of the first embodiment will be explained based on FIG. 2 and FIGS. 3(a) to 3(c). As shown in FIG. 2, for example, a magnet 2 is placed near a ferromagnetic magnetoresistive element 3, and the direction of magnetic flux crossing the ferromagnetic magnetoresistive element 3 changes as the magnet 2 rotates in the direction of arrow A. First, when the first input terminal T1 is connected to Vcc and the second input terminal T2 is connected to GND, and a desired voltage is input to the full bridge, the first output terminal T3 is connected to the first magnetoresistive element MR1 and the second magnetoresistive element MR1. A voltage value resistance-divided by the resistor MR2 is output, and a voltage value resistance-divided by the third magnetoresistive element MR3 and the fourth magnetoresistive element MR4 is outputted to the second output terminal T4.

Next, when the direction of the magnetic flux crossing the ferromagnetic magnetoresistive element 3 changes as the magnet 2 rotates, the first magnetoresistive element MR1 and the second magnetoresistive element MR2 exhibit opposite resistance changes. Therefore, a sinusoidal voltage waveform is outputted to the first output terminal T3 as shown in FIG. 3(a). Further, the third magnetoresistive element MR3 and the fourth magnetoresistive element MR4 exhibit opposite resistance changes, and the third magnetoresistive element MR3 and the first magnetoresistive element MR1 exhibit the same resistance value change, and Fourth magnetoresistive element MR
4 and the second magnetoresistive element MR2 are arranged so as to exhibit the same change in resistance value, so that the second output terminal T4 has the same resistance value as shown in FIG.
As shown in (b), an output waveform having an opposite phase to the output waveform from the first output terminal T3 is output. Here, if we take the difference between the first output terminal T3 and the second output terminal T4, we can see (c) in FIG.
An output waveform as shown in is obtained, and the rotation angle of the magnet 1 is detected from this output voltage value. This output waveform is shown in Figure 1.
The amplitude twice that of the output waveform of the conventional ferromagnetic magnetoresistive element 1 shown in FIG. 0(b) is obtained. Also, the first to fourth
Since the magnetoresistive elements MR1 to MR4 are made of ferromagnetic magnetoresistive material, they each exhibit the same resistance value change with respect to environmental temperature changes, and the output can be determined by taking the difference between the outputs of the output terminals T2 and T4. The influence of environmental temperature can be removed from the voltage, and the rotation angle of the magnet 2 can be detected with high precision without the need for special temperature characteristic correction means.

Example 2. FIG. 4 is a side view showing a second embodiment of the present invention, and FIGS. 5(a) and 5(b) are plan views showing the configuration of the ferromagnetic magnetoresistive element 3 in the second embodiment, respectively. This Example 2 specifically shows the ferromagnetic magnetoresistive element 3 according to the present invention, and includes a ferromagnetic magnetoresistive element 3a having first and second magnetoresistive elements MR1 and MR2, and a third and fourth magnetoresistive element 3a. The ferromagnetic magnetoresistive element 3 is laminated with the ferromagnetic magnetoresistive element 3b having the magnetoresistive elements MR3 and MR4.
It consists of

A ferromagnetic magnetoresistive material, for example, Ni--Fe, is deposited on a glass substrate 5a to form first and second magnetoresistive elements MR1 and MR2 in comb-like patterns perpendicular to each other. 2 magnetoresistive elements MR1, MR2 are provided with Au wiring 6 at both ends, and lead terminals 4a, 4 are attached to each wiring 6.
b and 4c are disposed and further molded with insulating resin to form the ferromagnetic magnetoresistive element 3a. Similarly, Ni-Fe
is deposited on the glass substrate 5b to form third and fourth magnetoresistive elements MR3 and MR4 in comb-like patterns perpendicular to each other, and Au wiring is provided at both ends of the third and fourth magnetoresistive elements MR3 and MR4. 6, and connect each wiring 6 with a lead terminal 4b,
4c and 4d are arranged and further molded with insulating resin,
A ferromagnetic magnetoresistive element 3b is formed.

Next, the first magnetoresistive element MR1 and the third magnetoresistive element MR3 are arranged in the same direction, and the second magnetoresistive element MR2 and the fourth magnetoresistive element MR4 are arranged in the same direction. The ferromagnetic magnetoresistive elements 3 are mounted on the circuit board 7 by stacking the ferromagnetic magnetoresistive elements 3a and 3b and soldering the respective lead terminals 4a to 4d to the wiring pattern on the circuit board 7. Here, depending on the wiring pattern of the circuit board 7, the lead terminals 4a to 4 of the ferromagnetic magnetoresistive elements 3a and 3b are
The same terminals of d are electrically connected to each other to form the ferromagnetic magnetoresistive element 3 shown in FIG.

Therefore, in the second embodiment, the patterns of the first magnetoresistive element MR1 and the second magnetoresistive element MR2 are orthogonal to each other, and the patterns of the third magnetoresistive element MR3 and the fourth magnetoresistive element M
Each of the magnetoresistive elements MR1 to MR4 is formed such that the patterns with R4 are orthogonal to each other, and the first magnetoresistive element MR1
The ferromagnetic magnetoresistive elements 3a, 3b are arranged so that the patterns of the second magnetoresistive member MR2 and the fourth magnetoresistive member MR4 are in the same direction, and the patterns of the second magnetoresistive member MR2 and the fourth magnetoresistive member MR4 are arranged in the same direction. Since the first magnetoresistive element MR1 is laminated, the first magnetoresistive element MR1
and the third magnetoresistive element MR3 have the same resistance value change with respect to the magnetic flux change, the second magnetoresistive element MR2 and the fourth magnetoresistive element MR4 have the same resistance value change with respect to the magnetic flux change, and the first magnetoresistive element MR3 has the same resistance value change with respect to the magnetic flux change. body MR1 (third magnetoresistive body MR3
) and the second magnetoresistive element MR2 (fourth magnetoresistive element MR4), the resistance value change with respect to the magnetic flux change is an opposite resistance value change.

In this way, the above embodiment 2 is similar to the above embodiment 1.
This is an example specifically showing the above, and the same effect can be achieved.

Example 3. FIG. 6 is a side view showing a third embodiment of the present invention, and FIGS. 7(a) and 7(b) are a top view and a bottom view, respectively, showing the configuration of the ferromagnetic magnetoresistive element 3 in the third embodiment of the present invention. . In the second embodiment, the ferromagnetic magnetoresistive element 3 is constructed by laminating the ferromagnetic magnetoresistive elements 3a and 3b.
, as shown in (b), the first and second magnetoresistive elements MR1 and MR2 are arranged in comb-shaped patterns perpendicular to each other on one surface of the glass substrate 5, and comb-shaped patterns perpendicular to each other are arranged on the other surface of the glass substrate 5. Third and fourth magnetoresistive elements MR3 and MR4 of the pattern
A wiring 6 is formed at each terminal of the first to fourth magnetoresistive elements MR1 to MR4, and each lead terminal 4a to 4a is connected to each wiring 6.
After connecting 4d, it is molded with insulating resin, and the same effect is achieved.

[0019]

[Effects of the Invention] As explained above, according to the present invention,
Using four magnetoresistive bodies made of ferromagnetic magnetoresistive material, the resistance value change with respect to magnetic flux change between opposing magnetoresistive bodies is the same resistance value change, and the resistance value with respect to magnetic flux change between adjacent magnetoresistive bodies. Since the full-bridge structure is constructed with the resistance value changing in the opposite direction, a ferromagnetic magnetoresistive element with a full-bridge structure can be obtained that can obtain a large output voltage and can detect with high precision without the need for special compensation means for temperature characteristics. It has the effect of being

[Brief explanation of drawings]

FIG. 1 is a circuit diagram schematically showing a first embodiment of the present invention.

FIG. 2 is a plan view for explaining the operation of the first embodiment of the present invention.

[Fig. 3] (a) to (c) are respectively Embodiment 1 of the present invention.
FIG. 3 is an output voltage waveform diagram showing the relationship between the rotation angle of the magnet and the output voltage in FIG.

FIG. 4 is a side view showing a second embodiment of the invention.

[Fig. 5] (a) and (b) are respectively Embodiment 2 of the present invention.
FIG. 2 is a plan view illustrating the structure of a ferromagnetic magnetoresistive element in FIG.

FIG. 6 is a side view showing a third embodiment of the invention.

[Fig. 7] (a) and (b) are respectively Embodiment 3 of the present invention.
FIG. 2 is a top view and a bottom view illustrating the structure of a ferromagnetic magnetoresistive element in FIG.

FIG. 8 is a circuit diagram schematically showing an example of a conventional full-bridge structure ferromagnetic magnetoresistive element.

FIG. 9 is a plan view for explaining the operation of a conventional full-bridge structure ferromagnetic magnetoresistive element.

10(a) and 10(b) are output voltage waveform diagrams showing the relationship between the rotation angle of the magnet and the output voltage in the conventional ferromagnetic magnetoresistive element shown in FIG. 8, respectively.

[Explanation of symbols]

3 Ferromagnetic magnetoresistive element 3a, 3b Ferromagnetic magnetoresistive element MR1 First magnetoresistive element MR2 Second magnetoresistive element MR3 Third magnetoresistive element MR4 4th magnetoresistive element T1 1st input terminal T2 2nd input terminal T3 1st output terminal T4 2nd output terminal

Claims (1)

[Claims] 1. Four magnetoresistive bodies made of a ferromagnetic magnetoresistive material are connected in series to form a bridge, and the resistance value change with respect to the magnetic flux change between the opposing magnetoresistive bodies is the same resistance value change, A change in resistance value due to a change in magnetic flux between adjacent magnetoresistive elements is treated as an opposite change in resistance value, a pair of diagonally facing connection points are used as input terminals, and another pair of diagonally facing connection points are used as output terminals. A ferromagnetic magnetoresistive element with a full bridge structure.