JPS5841448Y2 - magnetically sensitive element - Google Patents

Description

[Detailed description of the invention] This invention is a magnetically sensitive element that can be used as a position detection device, etc.
In particular, the present invention relates to improvements in magnetically sensitive elements that are sensitive to the magnitude of magnetic fields using ferromagnetic metal magnetoresistive elements.

As shown in FIG. 1, two first and second current paths 1.2 are formed from a ferromagnetic material having a magnetoresistance anisotropy effect,
Magnetization is saturated in ferromagnetic metal magnetoresistive elements arranged so as to be orthogonal to each other, connected in series at their midpoint terminal b (voltage terminal), and configured to supply power to terminals a and c (current terminals). It is known that if a sufficient magnetic field is applied in the plane of the element and the direction of the field changes, the voltage across the midpoint terminal will change.

Conventional position detection devices that utilize this principle, such as origin detectors for magnetic scales, are configured to apply a bias magnetic field in the same direction to both members, and when the magnetoresistive element rotates within the origin magnetic field. However, there is a drawback that the output voltage fluctuates based on the above-mentioned magnetism principle, resulting in zero drift.

In order to eliminate the drawbacks of the conventional device mentioned above, the inventor of the present invention aims to reduce the output drift caused by changes in the magnetic field angle near zero output, and also to provide a new analog type sensor.
A magnetic sensor (Patent Application No. 53, 1983) constructed in such a way that a bias magnetic field in opposite directions is applied to each of the ferromagnetic members arranged in the same direction, so that it is sensitive to the strength of the magnetic field and exhibits magnetic flux responsive characteristics. -34096).

Figure 2 shows the above magnetic sensor, and in the figure 3
and 4 are first and second current paths which are connected to a magnetoresistive thin film member made of a ferromagnetic alloy similar to the ferromagnetic member shown in FIG. 1, and both paths are arranged in the same direction. It differs from FIG. 1 in that it is

Then, resistors R1 and R2 are connected to each member,
and voltage V.

is applied, and bias magnetic fields Ha and Hs in opposite directions are applied.

With this configuration, it is possible to obtain a magnetic sensor that responds to the magnitude of a signal magnetic field and generates an output voltage similar to that of a conventional analog sensor such as a differential transformer.

On the other hand, the magnetoresistive element shown in FIG. 1 is connected to resistors RA and R8 as shown in FIG.

is applied and a bias magnetic field HB is applied in a direction that is 45 degrees to the magnetic sensing direction, it is perpendicular to H8 or 45
In response to the signal magnetic field H3 in the ° direction, the output voltage exhibits characteristics as shown in FIGS. 4a and 4b.

When the bias magnetic field HB related to each ferromagnetic member 1 and 2 is decomposed in the above-mentioned state of applying a bias magnetic field in the 45° direction to the magnetoresistive element, it becomes as shown in FIG. 5a. When one ferromagnetic member, for example member 2, is rotated by ±90° with respect to member 1 while keeping the angle between its current direction and bias magnetic field direction constant at 45°, that is, both members are arranged in parallel. fifth in relationship
The magnetic sensitivity characteristics of the cases shown in FIG. 8C and FIG.

The present invention has been made with attention to this point, and the first and second current paths, which are made of ferromagnetic members arranged in series and in the same direction as each other, are arranged at an angle of about 45° with respect to the direction of the paths. The present invention is characterized in that it is configured to apply bias magnetic fields that are perpendicular to each other and that are perpendicular to each other, and will be further described below with reference to the embodiments shown in FIGS. 6 and 8.

First, Figure 6 a-1 to a-3, b-1 to b-3 and C1 to
c-3 is a signal magnetic field Hs in a direction of approximately 90° with respect to the bias magnetic field HB in the embodiments shown in a, l) and C of the same figure, respectively.
It shows the current direction of the ferromagnetic members 3 and 4 and the direction of the composite magnetic field H''HB+H3 when applying .

As is well known, when only the bias magnetic field HB is applied to each ferromagnetic member of the ferromagnetic magnetoresistive element in the 45° direction,
Alternatively, when the composite magnetic field H of the bias magnetic field HB and the signal magnetic field H8 is applied to both members in a 45° direction, each member 3
, 4 resistance r1. r2 is r1=r2 and the output voltage is ■
=O.

Now, as shown in Figure 6 a-1 to a-3, when the signal magnetic field H8 is applied and its magnitude is changed, the resultant magnetic field HB
+H5=H changes its magnitude and direction as shown.

That is, in FIG. 6a-1, the resistance r1 of the ferromagnetic member 3 increases, and the resistance r2 of the ferromagnetic member 4 remains unchanged.

Therefore, it can be seen that the output voltage V gradually increases in the negative direction.

In FIG. 6a-2, the resistance r1 of the ferromagnetic member 3 is the maximum, and the resistance r2 of the ferromagnetic member 4 remains unchanged, so the output voltage ■ reaches a negative extreme value.

Further, as shown in FIG. 6a-3, when the signal magnetic field H8 is increased, the resistance r1 starts to decrease and the resistance r2 remains unchanged, so the output voltage (2) gradually increases toward zero.

When the signal magnetic field H5 is infinite, each ferromagnetic member exhibits a direction of 45° with respect to the composite magnetic field H, and therefore the output voltage (2) approaches zero.

Next, when the signal magnetic field H8 is applied in a direction opposite to that in the illustrated example, it is clear that the output voltage (2) increases and decreases in the positive direction and reaches a positive extreme value at HB-H5.

Figure 6 shows that the magnetic sensitivity characteristics in the case of Figure 6A are symmetrical compared to the case in Figure 6A, and the magnetic sensitivity characteristics in the case of Figure C show almost the same tendency as Figure 6A. C1~c-3 and C-1~
It can be easily estimated by referring to each figure of c-2.

Thus, the magnetic sensitivity characteristics of each of the ferromagnetic members shown in FIGS. 6a to 6C are displayed as shown in FIG. 7.

Further, when the signal magnetic field H5 is applied in the current direction of the ferromagnetic member as shown in FIGS.

First, in FIG. 8 II, the resistance r of the ferromagnetic member 3 increases, and the resistance r2 of the ferromagnetic member 4 decreases.

Furthermore, in FIG. 8 III, as the signal magnetic field Hs increases, the resistance r1 further increases, and the resistance r2 becomes minimum.

In Fig. 8 IV, the resistance r1 has further increased, but the resistance r2 has also started to increase, and the signal magnetic field H5 is shown in Fig. 8 IV.
continues to increase and reaches infinity, rl-=r2 (maximum value)
It can be seen that it reaches .

Therefore, the output voltage V becomes as shown in FIG.

As is clear from the above explanation, the magnetically sensitive element of the present invention is sensitive to the strength of an applied magnetic field and exhibits magnetic flux responsive characteristics in the same way as the conventional electric shock transducer element, and is equipped with a magnet generating body that generates the above-mentioned signal magnetic field. In this case, a desired position detector or the like can be easily obtained, and in that case, the output fluctuation due to rotation is relatively small, and it can be widely used as an analog measurement sensor.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a conventional ferromagnetic magnetoresistive element, Figure 2
Figures 1 and 1i are schematic diagrams of other conventional ferromagnetic magnetoresistive elements and their bridge circuit diagrams, Figures 3a and l) are bridge circuit diagrams of the element in Figure 1, and Figures 4a and l) respectively. 5 is an output characteristic diagram, FIGS. 5 a to 5 c are explanatory diagrams of the basic principle of the present invention, FIGS. 6 a, 1), c, and 8 I are route maps showing each embodiment of the present invention, respectively. Figure 6 a-1 to a-3, Figure 6 C-
1 to b-3, Figure 6 C-1 to c-3, and Figure 8 II to ■
are vector diagrams for explaining the operation of the above embodiments, FIG. 7 is an output characteristic diagram of each embodiment of FIG. 6, and FIG. 9 is an output characteristic diagram of the embodiment of FIG. 8. 1 to 4: ferromagnetic member, 3: ferromagnetic magnetoresistive element, RA
, RB: resistance, HB: bias magnetic field, H5: signal magnetic field.

Claims (1)

[Claims for Utility Model Registration] First and second current paths each made of a ferromagnetic material having an anisotropic magnetoresistance effect are connected in series, and the first and second current paths are connected in the same direction, respectively. an output terminal is provided at the connection point of the first and second current paths, a current supply terminal is provided at the other end of the first and second current paths, and A magnetically sensitive device characterized in that a bias magnetic field is applied to the first and second current paths, respectively, in a direction approximately 45 degrees from the first and second current path directions and perpendicular to each other. element.