JPH0777165B2 - Non-contact type potentiometer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-contact potentiometer for rotating a rotor, and particularly to a non-contact potentiometer using a ferromagnetic magnetoresistive element whose resistance value is reduced by a magnetic field. .

[Prior Art] A magnetic circuit of a non-contact potentiometer has conventionally been configured as a closed magnetic circuit together with a bottomed cylindrical core, a rotating magnetic body and a permanent magnet, and a magnetoresistive element is provided in a gap formed at the tip of the rotating magnetic body. InSb is arranged to generate an output according to the rotation of the rotating magnetic body.In other words, by changing the size of the gap formed at the tip of the rotating magnetic body, in other words, the tip of the rotating magnetic body. Is processed by a predetermined function to obtain a predetermined function output from the InSb magnetoresistive element as described above.

[Problems to be Solved by the Invention] In this case, it is considered that the permanent magnet as the magnetic field generating means is magnetized so that the magnetic poles are oriented in the radial direction as in the previously proposed Japanese Patent Application No. 61-72201. However, it is not easy to magnetize the arc-shaped permanent magnet in this way, and it is difficult to magnetize it.

This invention was made to eliminate this problem.
Even if the magnetic field generating means has any shape such as an arc shape or a non-linear shape, it suffices to magnetize in a direction orthogonal to the above-mentioned radial direction, which is excellent in that it can be easily magnetized. An object is to provide a non-contact potentiometer having an effect.

[Means for Solving the Problems] According to the present invention, a housing, a movable portion rotatably provided in the housing, and a movable portion arranged concentrically with the movable portion with a predetermined distance from the movable portion. A planar insulating substrate having a pair of ferromagnetic magnetoresistive elements that are provided in an annular shape as a whole, and a magnetic pole on the movable portion side that is directed in the rotation axis direction of the movable portion, and the ferromagnetic magnetoresistive element. Magnetic field generating means mounted so as to face a part of the insulating substrate located on one side surface of the element, and the magnetic flux from the magnetic field generating means is directed in the radial direction of the annular ferromagnetic magnetoresistive element. The configuration employs a feature that a closed magnetic circuit is formed by directing.

[Operation] According to the present invention configured as described above, even when the magnetic field generating means has an arc shape as an example, the magnetization direction of the magnetic field generating means is not the radial direction but the direction perpendicular to the radial direction, that is, the plane of the insulating substrate. Since it is only necessary to make a perpendicular direction, it becomes easy to magnetize the magnetic field generating means.

[Effects of the Invention] According to the present invention configured as described above, even if the magnetic field generating means has a non-linear shape such as any shape regardless of the arc shape or the angular shape, the magnetization direction of the magnetic field generation means is the axis of the rotor. It is possible to provide a non-contact potentiometer which has an excellent effect that the magnetic field generating means can be easily magnetized because the magnetic field generating means can be easily magnetized. Further, since the shape of the magnetic field generating means is arbitrary, the characteristics can be set freely.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. First, FIGS. 1A and 1B show a first embodiment of the present invention. In FIG. 1, ferromagnetic magnetoresistive elements 2a and 2b made of thin films of circular or polygonal shape Ni-Fe, Ni-Co or the like having an opening portion are formed on an insulating substrate 1, and both terminal portions, and The electrodes 3, 4, and 5 are formed at the midpoints. (So-called half bridge formation). The output terminal Vout is derived from the midpoint 5 with the electrode terminal 3 of the ferromagnetic magnetoresistive elements 2a and 2b as the ground GND and the electrode terminal 4 as the power supply terminal Vcc. A bearing 8 formed of a ball bearing on the upper lid 9a is provided at the center of the printed pattern of the ferromagnetic magnetoresistive elements 2a and 2b. Bearing 8
A rotary shaft 6 made of a non-magnetic material and vertically oriented is rotatably supported around the shaft as a movable portion. A semi-circular arc-shaped permanent magnet 7 is attached as magnetic field generating means to one side of the rotary shaft 6 via a plate-shaped attachment member 9 made of a magnetic material. The permanent magnet 7 is magnetized along the axial direction of the rotary shaft 6, that is, in the direction orthogonal to the radial direction of the permanent magnet 7. The permanent magnet 7 is arranged so as to face the one ferromagnetic magnetoresistive element 2a in the vertical direction on the side surface of the outer circumference thereof. In addition, 10 is a housing and 11 is a wire harness.

The following facts are theoretically known in the ferromagnetic magnetoresistive elements 2a and 2b. That is, a ferromagnetic magnetoresistive element has a characteristic that when a magnetic field is applied from a direction perpendicular to the direction of current flow, the resistance value of that portion decreases.
Further, when receiving a magnetic field equal to or higher than the saturation magnetic field, the decrease in the resistance value becomes constant, and unlike the semiconductor type magnetoresistive element and the Hall element, it has a characteristic that a stable output can be obtained.

Next, a ferromagnetic magnetoresistive element that directly faces the permanent magnet 7.
As shown by an arrow H in FIG. 1 (b), a magnetic field is applied to 2a in the vertical direction along the axial direction of the rotary shaft 6, and this magnetic field is applied to the ferromagnetic magnetoresistive element 2a as shown in FIG. ) Acts in the radial direction as indicated by the arrow i, and its resistance value decreases. With the rotation of the rotating shaft 6, the resistance value of the ferromagnetic magnetoresistive element 2a becomes the second value.
As shown in the figure, it changes continuously and the output of the potentiometer becomes almost linear. In the case of FIG. 2, the vertical axis represents the output (Vcc) and the horizontal axis represents the rotation angle (degree) of the rotary shaft 6.

In this way, while forming the permanent magnet 7 in a semi-circular shape,
Since the magnetizing direction of the permanent magnet 7 is not the radial direction but the direction orthogonal to the radial direction, the magnetizing is facilitated, and the magnetic field generating means is easily manufactured, which is advantageous in cost.

Further, when a semiconductor magnetoresistive element or a Hall element is used, variations in magnetic field strength greatly affect the characteristics, but when a ferromagnetic magnetoresistive element is used as shown in this embodiment, a magnetic field above the saturation magnetic field is used. If is applied in advance, a stable output of the potentiometer can be obtained in the embodiment.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b).
Will be described with reference to. The second embodiment is different from the first embodiment in that the mounting member 9 is attached to the rotary shaft 6 in the second embodiment.
That is, the circular magnetism collecting member 15 is attached directly to the lower end of the, and the circular magnetism collecting member 15 is attached to the center of the ferromagnetic magnetoresistance element. One end of an attachment member 9 made of a magnetic material is attached to the lower end of the rotary shaft 6, and a permanent magnet 7 is attached to the other end of the attachment member 9 with an adhesive or the like. The permanent magnet 7 is located on the outer peripheral surface of the ferromagnetic magnetoresistive element.

5 (a) and 5 (b) show a third embodiment of the present invention.

In the third embodiment, the rotor 12 is attached to the lower end of the rotary shaft 6, and the magnetic flux collecting member 13 made of a magnetic material and having a U-shaped cross section is attached to the lower surface of the rotor 12. Then, one end of the magnetism collecting member 13 is positioned at the center of the ferromagnetic magnetoresistive elements 2a and 2b,
The other end is located on the outer periphery of the ferromagnetic magnetoresistive element 2a and has a permanent magnet 7 attached thereto. You may comprise in this way.

6 (a) and 6 (b) show a fourth embodiment of the present invention.
In the fourth embodiment, in the state of the second embodiment, the permanent magnet 14 is attached to the lower end of the rotary shaft 6 with an adhesive or the like. The permanent magnet 14 and the permanent magnet 7 have the same direction of the magnetic poles and are set to have different polarities.
With this structure, a closed circuit is generated between the permanent magnet 7 and the permanent magnet 14 as indicated by i in FIG. 6B, but at this time, the magnetic flux passing through the ferromagnetic magnetoresistive element 2a increases. Therefore, the characteristics shown in FIG. 7 are obtained. In FIG. 7, the vertical axis represents output (Vout) and the horizontal axis represents rotation angle (degrees). According to this, it is understood that the rising is large and a large output is obtained as compared with the first embodiment.

Although the ferromagnetic magnetoresistive elements 2a and 2b have a circular or polygonal shape in the above embodiment, the shape is not limited to this and may be, for example, a strip shape.

When the ferromagnetic magnetoresistive element is formed in a linear shape, the magnetic field generating means may also be formed in a linear shape so as to extract the linear displacement. Further, the rotor may have both linear movement and rotational displacement.

Furthermore, in each of the above-described embodiments, the permanent magnet is configured to be rotationally displaced with respect to the ferromagnetic magnetoresistive element, but conversely, the ferromagnetic magnetoresistive element may be displaced with respect to the permanent magnet. However, such a structure requires a structure in which a terminal led out to the outside is slidable so as to be electrically conductive, which is a disadvantage that the entire structure is complicated. For this reason, in this embodiment, the above configuration was not adopted.

In addition, in concrete implementation, various modifications can be made without departing from the gist of the invention.

[Brief description of drawings]

FIG. 1 shows an embodiment of the potentiometer of the present invention. FIG. 1 (a) is a top view thereof and FIG. 1 (b) is a sectional view taken along line AA. FIG. 2 is an output characteristic graph showing the relationship between the rotation angle and the output, FIG. 3 is a graph showing the characteristic of the strong magnetic magnetoresistive element, and FIGS. 4 (a) and 4 (b) are top views of the second embodiment. And a sectional view, FIGS. 5 (a) and 5 (b) are a top view and a sectional view of the third embodiment, and FIGS. 6 (a) and 6 (b) are a fourth embodiment of the present invention.
FIG. 7 is a top view and a sectional view showing an embodiment, and FIG. 7 is a graph showing characteristics showing a fourth embodiment of the present invention. In the figure, 1 ... Insulating substrate (circuit board), 2a, 2b ... Ferromagnetic magnetoresistive element, 3 ... Permanent magnet (magnetic field generating means), 6 ...
… Rotary shaft (movable part), 10 …… Housing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Ariga 1-1, Showa-cho, Kariya, Aichi Nihon Denso Co., Ltd. (72) Inventor Toshikazu Matsushita 1-1, Showa-cho, Kariya, Aichi Nihon Denso Within the corporation

Claims (3)

[Claims] 1. A housing, a movable part rotatably provided in the housing, a concentric part provided to the movable part at a predetermined distance from the movable part, and an annular shape as a whole. A planar insulating substrate having a pair of ferromagnetic magnetoresistive elements, the magnetic pole being directed to the movable portion side in the rotation axis direction of the movable portion and being located on one side surface of the ferromagnetic magnetoresistive element A part of the insulating substrate, and a magnetic field generating means mounted so as to face each other, and a magnetic flux from the magnetic field generating means is directed in a radial direction of the annular ferromagnetic magnetoresistive element to form a closed magnetic path. A non-contact type potentiometer characterized in that 2. The magnetic field generating means is arranged in the vicinity of the inside or outside of the ferromagnetic magnetoresistive element, and the movable part is provided with a magnetic collecting member made of a magnetic material for collecting the magnetic field generating means. 2. The non-contact potentiometer according to claim 1, wherein the ferromagnetic magnetoresistive element is provided at a position sandwiching the ferromagnetic magnetoresistive element in the radial direction of the ferromagnetic magnetoresistive element together with the magnetic field generating means. 3. The non-contact potentiometer according to claim 1 or 2, wherein the magnetic field generating means comprises a permanent magnet.