JPH0777163B2 - Potentiometer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a potentiometer, and more particularly to a non-contact potentiometer.

[Conventional technology]

The magnetic circuit of a non-contact potentiometer is conventionally configured as a closed magnetic circuit together with a bottomed cylindrical core, a rotating magnetic body and a permanent magnet, and InSb, which is a magnetoresistive element, is placed in a gap formed at the tip of the rotating magnetic body. , The output is generated according to the rotation of the rotating magnetic body, and by changing the size of the gap at the tip of the rotating magnetic body, in other words, the tip of the rotating magnetic body is processed by a predetermined function. As a result, a predetermined function output is obtained from InSb.

[Problems to be solved by the invention]

However, in the above-mentioned non-contact potentiometer shown in the prior art, it is very difficult to process the tip of the rotating magnetic body so as to have a predetermined function shape, and if the gap has a narrow portion and a wide portion, the magnetic flux The magnetic flux density is not uniform because it concentrates on a narrow area. For this reason, the linearity of the output of InSb, which is a magnetoresistive element, varies, and the manufacturing yield of the non-contact potentiometer was very low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a non-contact potentiometer having a good output linearity and a relatively high manufacturing yield.

[Means for solving problems]

In order to achieve the above object, the potentiometer of the present invention comprises a ferromagnetic magnetoresistive element and magnetic field generating means arranged at a predetermined interval from the ferromagnetic magnetoresistive element, and the magnetic field generating means is The absolute value of the strength of the magnetic field applied to the ferromagnetic magnetoresistive element is equal to or higher than the saturation magnetic field strength of the ferromagnetic magnetoresistive element, and the ferromagnetic magnetoresistive element and the magnetic field generating means are relatively aligned along a fixed line. The feature is that they are moved automatically.

[Action]

Then, according to the above means, the magnetic field generating means is relatively moved along a fixed linearity by utilizing the fact that the resistance value of the ferromagnetic magnetoresistive element changes (decreases) when it receives a magnetic field. Causes the resistance value of the ferromagnetic magnetoresistive element to change continuously, and the change is output as, for example, a voltage change, so that the output exhibits linearity, and the absolute value of the magnetic field strength is the saturation magnetic field strength of the ferromagnetic magnetoresistive element. With the above, the change in the resistance value of the ferromagnetic magnetoresistive element is not changed due to some variation in the magnetic field strength and is substantially constant.

〔Example〕

The present invention will be described below with reference to the embodiments shown in the drawings. First
An embodiment of the present invention is shown in the figure, a top view thereof is shown in the same figure (a), and a cross-sectional view taken along line AA in the same figure is shown in the same figure (b). In the figure, the structure is a circular or polygonal shape (the former is the figure) with an opening on the insulating substrate 1, and Ni-Fe, N
Forming a ferromagnetic magnetoresistive element 2 composed of a thin film of i-Co,
Electrically connecting one end of the opening to a power supply voltage V _cc ,
The other terminal is grounded (GND). Further, the output terminal V _out is taken _out from within the ferromagnetic magnetoresistive element 2 (in the present embodiment, at the midpoint of the ferromagnetic magnetoresistive element 2). And
A fan-shaped permanent magnet 3 is attached at a predetermined distance from the ferromagnetic magnetoresistive element 2 on the side of the ferromagnetic magnetoresistive element 2 of the insulating substrate 1 (upper side in the figure (b)) or the opposite side (lower side in the figure (b)). Has been. (The figure shows the former). The permanent magnet 3 rotates in the circumferential direction of the ferromagnetic magnetoresistive element 2 with the center of the ferromagnetic magnetoresistive element 2 as the center of the rotation axis. The absolute value of the strength of the generated magnetic field is equal to or higher than the saturation magnetic field strength of the ferromagnetic magnetoresistive element 2. In addition, the magnetic field of the ferromagnetic magnetoresistive element 2
Is applied in the direction perpendicular to the circumferential direction (longitudinal direction in the present invention), that is, in the radial direction.

Next, the operation of the potentiometer having the above structure will be described.
The resistance value of the ferromagnetic magnetoresistive element 2 decreases when the permanent magnet 3 receives a magnetic field from a direction perpendicular to the current direction. Then, as the permanent magnet 3 rotates in the circumferential direction of the ferromagnetic magnetoresistive element 2, the portion where the resistance value decreases in the ferromagnetic magnetoresistive element 2 also continuously rotates. Therefore, the output as a divided voltage value of the power supply voltage _Vcc determined by the ratio of the resistance value between the GND terminal and the output _Vout terminal and the resistance value between the output _Vout terminal and the power supply voltage _Vcc terminal. The value of V _out has linearity as shown in FIG. In addition, in FIG. 2, the rotation angle 0 deg means that the straight side 3a of the permanent magnet 3 in FIG. 1 is perpendicular to the line AA in the figure, and the permanent magnet 3 is arranged on the left side in the figure. It's time. Further, FIG. 2 shows the characteristic of rotating rightward from that position in FIG. 1,
Either direction of rotation may be used. The ferromagnetic magnetoresistive element 2 has a magnetic field strength (absolute value) equal to or higher than the saturation magnetic field (one-dot chain line in the figure) as shown in the characteristic (solid line in the figure) of the graph of FIG.
When receiving, the decrease of the resistance value becomes constant (the resistance value becomes almost constant), so that the value of the output V _out may depend on the mounting error of the permanent magnet 3 and some fluctuation of the magnetizing strength. Disappear. In addition, in FIG. 6, the characteristics of InSb are simultaneously shown by the dotted line, but it can be seen that the resistance value of InSb increases as the magnetic field strength increases.

Therefore, according to the present embodiment, it is possible to provide a non-contact potentiometer having a good output linearity and a relatively high manufacturing yield, without strict selection of magnets and strict control of mounting.

The present invention is not limited to the above embodiment, and various modifications can be made as shown below, for example, without departing from the spirit of the invention.

(1) Although the ferromagnetic magnetoresistive element 2 has a circular or polygonal shape in the above embodiment, it may be a strip-shaped ferromagnetic magnetoresistive element 4 as in the other embodiments shown in FIG. Therefore, the permanent magnet 5 can also be a linear non-contact potentiometer with a rectangular shape. In the case of this embodiment, the permanent magnet 5 translates in the longitudinal direction of the ferromagnetic magnetoresistive element 4 to change the resistance value of the ferromagnetic magnetoresistive element 4. Then, accordingly, the output V _out becomes linear as shown in FIG.

(2) The position of the terminal V _out for taking _out the output from the ferromagnetic magnetoresistive elements 2 and 4 may be anywhere within the ferromagnetic magnetoresistive elements 2 and 4. In the embodiment shown in FIG. 1, the position of the terminal V _out is the midpoint of the ferromagnetic magnetoresistive element 2, and the shape of the permanent magnet 3 is a semicircular sector, that is, the magnetic field generated from the permanent magnet 3 is strong. The output V _out is sensitively applied to the rotation of the permanent magnet 3 so that it is applied to half of the magnetic magnetoresistive element 2. For example, the permanent magnet 3 is a quarter. If it is a circular sector, the output V will start while the rotation starts from 0deg and the angle moves 90deg.
This is because there is no change in the _out value, so it is avoided. Therefore, when considering such a thing, the output terminal V _out
It may be desirable to change the shape of the permanent magnet 3 depending on the number of the magnets and the position within the ferromagnetic magnetoresistive element 2.

(3) In the above embodiment, the permanent magnet 3,
Although 5 is used, other means for generating a magnetic field, such as an electromagnet, may be used.

(4) For example, as for the embodiment shown in FIG. 1, another ferromagnetic magnetoresistive element 20 is formed at a predetermined position on the insulating substrate 1 as shown in the application shown in FIG. It is also possible to electrically connect a resistor 21 to and take _{out the} output V _out ′ from a point between them. According to this embodiment, the permanent magnet 3 starts to rotate from the rotation angle 0 deg and the angle is
In the vicinity of 90 deg, the signal of the output V _out ′ changes, and the position of the permanent magnet 3 can be easily detected. Needless to say, the present invention may include only the ferromagnetic magnetoresistive element 20 or the structure without the ferromagnetic magnetoresistive element 2.

〔The invention's effect〕

As described above, according to the present invention, a potentiometer having a linear output is realized by utilizing the fact that the resistance value of a ferromagnetic magnetoresistive element changes (decreases) when it receives a magnetic field. When the element receives a magnetic field strength higher than the saturation magnetic field, the change in its resistance value becomes almost constant regardless of some variations in the magnetic field strength, machine differences, etc. There is an effect that a non-contact potentiometer having a relatively high yield can be provided.

[Brief description of drawings]

FIG. 1 shows an embodiment of the potentiometer of the present invention,
A top view thereof is shown in FIG. 9A and a cross-sectional view taken along the line AA is shown in FIG. 2 is a graph showing the output characteristics of the embodiment shown in FIG. 1, FIG. 3 is a configuration diagram of another embodiment of the potentiometer of the present invention, and FIG. 4 is a graph showing the output characteristics of the embodiment shown in FIG. FIG. 5 is a top view of the embodiment as an application of the embodiment in FIG. 1, and FIG. 6 is a graph showing the characteristics of the ferromagnetic magnetoresistive element. 1 ... Insulating substrate, 2, 4, 20 ... Ferromagnetic magnetoresistive element, 3, 5 ...
…permanent magnet.

Claims (3)

[Claims] 1. A ferromagnetic magnetoresistive element, and magnetic field generating means arranged at a predetermined distance from the ferromagnetic magnetoresistive element. The magnetic field generating means applies magnetic field to the ferromagnetic magnetoresistive element. The absolute value of the intensity is equal to or higher than the saturation magnetic field intensity of the ferromagnetic magnetoresistive element, and the ferromagnetic magnetoresistive element and the magnetic field generating means are relatively moved along a constant linear shape. . 2. The potentiometer according to claim 1, wherein the magnetic field generated by the magnetic field generating means is applied in a direction perpendicular to the longitudinal direction of the ferromagnetic magnetoresistive element. 3. The potentiometer according to claim 1 or 2, wherein the moving direction of the magnetic field generating means is the longitudinal direction of the ferromagnetic magnetoresistive element.