JPS6336585A - Non-contact potentiometer - Google Patents

Abstract

PURPOSE:To obtain a potentiometer characterized by a simple constitution and a large resistance value, by forming two ferromagnetic magnetoresistance elements on an insulating substrate with one central position as a reference in a spiral shape, and providing a freely rotating magnetic-field generating means with a specified interval being provided from the magnetoresistive element. CONSTITUTION:First and second ferromagnetic magnetoresistance elements 12a and 12b are provided in a spiral shape on the plane of an insulating substrate, with the same central position as a reference. A magnetic field generating means 16, which is set for free rotation, is provided with a specified interval being provided from the first and second ferromagnetic magnetoresistance elements 12a and 12b. A magnetic field, which is in parallel with the surface of the insulating substrate 11, is made to act on the first and second ferromagnetic magnetoresistance elements 12a and 12b. For example, the ferromagnetic magnetoresistance elements 12a and 12b are formed so that they have the angular difference of 90 degrees with respect to the spiral center. A square magnet 16 is provided thereon at a specified interval. The direction H of the magnetic field, which is applied on the ferromagnetic magnetoresistance elements 12a and 12b from the square magnet 16, is rotated on the horizontal plane when a rotary shaft 17 is rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a non-contact potentiometer used, for example, for detecting a rotation angle.

[Prior Art] For example, potentiometers used to detect rotation angles are mainly sliding contact types that use conductive plastic resistors, and especially integrally molded potentiometers. Excellent in terms of sliding life, rotational torque, etc. However, with the spread of mechatronics in recent years, demands for noiselessness, long life, high followability, etc. have further increased, and in order to meet these demands, for example, I
Non-contact potentiometers using semiconductor magnetoresistive elements such as nSb have been developed.

The resistance of this type of magnetoresistive element changes in proportion to the strength of the magnetic field, but because the element is mounted on a very small substrate, the length of the element is limited and the resistance value is small. There is a tendency. Therefore, there have been cases where the potentiometer does not match the circuit to be combined with the potentiometer or the required output characteristics.

[What the invention is trying to solve] This invention was made in view of the above points, and has a simple structure and a large resistance value. It is intended to provide a contact potentiometer.

゛[Means for solving the problem] That is, in the non-contact potentiometer according to the present invention, two ferromagnetic magnetoresistive elements are independently spirally formed on an insulating substrate with one center position as a reference. The magnetic field generating means is formed at a predetermined distance from these two ferromagnetic magnetoresistive elements and rotates about the reference position.

[In other words, in a non-contact potentiometer using the above means, the resistance values of the two ferromagnetic magnetoresistive elements are relatively changed as the magnetic field generating means rotates. , by configuring these two ferromagnetic magnetoresistive elements as two sides of a half-bridge circuit, for example,
It becomes possible to obtain rotation angle detection characteristics. Also,
Even if the substrate is as small as, for example, 4 mm square, the length of the element portion that acts as a resistance value can be increased because it is formed in a spiral shape. Therefore, by changing the shape of this spiral, an arbitrary relatively large resistance value can be obtained.

[Example] The present invention will be described in detail below with reference to the drawings. FIG. 1 shows the principle structure of a non-contact potentiometer according to an embodiment of the present invention. As shown in FIG. First and second ferromagnetic magnetoresistive elements L2a and 12b are formed.

These ferromagnetic magnetoresistive elements 12a and 12b are each formed in a spiral shape outward from the center of the insulating substrate 11, and an electrode 13 is formed in the center. In this case, the starting end of the ferromagnetic magnetoresistive element 12b, which is the center of the spiral, is connected to the electrode 13 in a state 90 degrees ahead of the starting end of the ferromagnetic magnetoresistive element 12a. is the ferromagnetic magnetoresistive element 1
This is used as a common electrode for 2a and 12b.

Further, a ferromagnetic magnetoresistive element 12a formed in a spiral shape,
Electrodes 14.15 are formed at the terminal ends of each of the electrodes 12b, and these electrodes 14.15 are also set to differ by 90 degrees. That is, the first and second ferromagnetic magnetoresistive elements 12a and L2b are set at different angles of 90 degrees with respect to the spiral center.

Here, the electrode 13 is used as an output terminal Vouts, the electrode 14 is used as a power supply terminal VCc-, and the electrode 15 is used as a ground terminal VSS, and the two sides of the bridge circuit are the ferromagnetic magnetoresistive elements 12a and L2b. I am trying to configure it.

Ferromagnetic magnetoresistive element 12a formed on insulating substrate 11
, 12b, a rectangular magnet 16 is set at a predetermined distance from each other, as shown in FIG. 1(B). That is, a magnetic field is applied horizontally to the plane of the substrate on which the ferromagnetic magnetoresistive elements L2a and 12b are formed (the direction of the magnetic field is indicated by an arrow H).

A rotating shaft 17 is fixed at the center of the square magnet 1B, and a ferromagnetic magnetoresistive element L2 is connected to the square magnet 1B.
The direction of the magnetic field applied to a and 12b rotates on the horizontal plane in which the ferromagnetic magnetoresistive elements 12a and 112b are formed as the rotating shaft 17 rotates. still,
The magnet may be a disc-shaped magnet.

FIG. 2 shows a specific configuration example of a non-contact potentiometer having the above-described structure.
is provided. For magnet mounting of the rotating shaft 17, a rectangular magnet 16 is fixed to the part 17a with, for example, adhesive.
As the rotating shaft 17 rotates, the square magnet 1B rotates. As explained in FIG.
Ferromagnetic magnetoresistive elements 12a and 12b are formed on the insulating substrate IL, and the bottom 2 of the case 20
It is designed to be set on a wiring board 22 provided on 0a.

Incidentally, the elements 12a and 12b cannot be shown in FIG. 2 because they are extremely thin. Further, lla is a solder connection portion that connects the substrate 11 and the wiring board 22.

As the direction of the magnetic field applied to the ferromagnetic magnetoresistive elements 12a, 12b approaches perpendicular to the direction of the current flowing through the ferromagnetic magnetoresistive elements 12a, 12b, the resistance value of that portion is reduced. , the resistance decreasing portions of the ferromagnetic magnetoresistive elements 12a, 12b are continuously moved.

Therefore, the resistance value of each ferromagnetic magnetoresistive element 12a, 12b changes as the square magnet 16 rotates as shown in FIG. Therefore, if the two ferromagnetic magnetoresistive elements 12a and 12b, whose resistance values are varied in this way, are used as two sides of a half-bridge circuit to obtain an output, it is possible to obtain an output according to the rotation angle. Become. (This point is similar to the earlier application, Japanese Patent Application No. 61-72201.) The rotation angle detection range can be effectively expanded.

The resistance value of the ferromagnetic magnetoresistive elements 12a, 12b decreases as the applied magnetic field strength increases, but when a magnetic field greater than the saturation magnetic field is applied, the resistance value does not decrease any further and remains at a constant value. There is a characteristic that becomes

Therefore, the square magnet 16 and the ferromagnetic magnetoresistive element 12a
, 12b, considering tolerances and variations in the magnetization strength of the rectangular magnets 16, even if these variations and tolerances exist, a magnetic field greater than the saturation magnetic field strength is applied to the ferromagnetic magnetoresistive elements 12a and 12b. If designed in such a way, it is possible to obtain stable output regardless of variations or differences in tolerance.

Moreover, the center electrode 13 is placed on the opposite side of the insulating substrate 11, that is, on the opposite side of the square magnet 1G so as not to hinder the rotation of the square magnet 1G.
It may be arranged by a through hole or the like on the side where B is not located.

In the above embodiment, the ferromagnetic magnetoresistive element 12a112
ferromagnetic magnetoresistive elements 12a are formed on the same plane of the insulating substrate L1, as shown in FIG.
Even if the resistors 12b and 12b are formed on the front and back sides of the insulating substrate 11, the resistance characteristics shown in FIG. 3 can be obtained.

Further, as shown in FIG. 5, the same effect can be obtained even if the ferromagnetic magnetoresistive elements 12a and 12b are formed on the front and back sides of the insulating substrate 11 in the same manner.

If formed in this manner, the required area of the insulating substrate 11 can be further reduced.

However, in this case, as shown in FIG.
It is necessary to connect 0b to configure a complete bridge circuit and take out the intermediate point outputs Voutl and Vo(7B).

[Effects of the Invention] As described above, according to the present invention, even when a small substrate is used, the length of the ferromagnetic magnetoresistive element can be made long and can be made arbitrarily, so that a relatively large resistance value can be achieved. This makes it possible to optimize the output characteristics of this type of extremely small sensor, which would otherwise have a too small resistance value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the principle structure of a non-contact potentiometer according to an eleventh embodiment of the present invention, FIG. 2 is a diagram showing a specific example of the structure of the non-contact potentiometer shown in FIG. 1, and FIG. The figure shows how the resistance value of the non-contact potentiometer shown in Fig. 1 changes, Fig. 4 shows the second embodiment of the invention, and Fig. 5 shows the third embodiment of the invention. FIG. 6, which is a diagram for explaining an embodiment, is a diagram showing a bridge circuit for obtaining an output from the non-contact potentiometer shown in FIG. 11... Insulating substrate, 12a, 12b... Ferromagnetic magnetoresistive element, 13.14.15... Electrode, [6...
Square magnet, 17... Rotating shaft, 20... Case, 2[
...Assistance. Applicant's agent Patent attorney Takehiko Suzue Figure 6

Claims (4)

[Claims] (1) First and second ferromagnetic magnetoresistive elements spirally formed on the plane of an insulating substrate with the same center position as a reference, and the first and second ferromagnetic magnetoresistive elements magnetic field generating means rotatably set at a predetermined distance from the first and second ferromagnetic magnetoresistive elements so as to apply a magnetic field parallel to the surface of the insulating substrate; A non-contact potentiometer featuring: (2) The first and second ferromagnetic magnetoresistive elements are formed on the same plane of the insulating substrate so as to be connected to a common electrode at one center reference position, and the first and second ferromagnetic magnetoresistive elements are The non-contact potentiometer according to claim 1, wherein an angular difference of 90 degrees is set between the ferromagnetic magnetoresistive elements. (3) The non-contact potentiometer according to claim 1, wherein the first ferromagnetic magnetoresistive element and the second ferromagnetic magnetoresistive element are respectively formed on different surfaces of the insulating substrate. . (4) A patent claim in which the magnetic field intensity applied from the magnetic field generating means to the first and second ferromagnetic magnetoresistive elements is greater than or equal to the saturation magnetic field of the first and second ferromagnetic magnetoresistive elements. The non-contact potentiometer according to item 1.