JP2001041768A - Magnetic potentiometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize with high accuracy an output signal corresponding to a rotational angle amount or a linear movement amount by constituting a magnetic member of a permanent magnet magnetized in a single pole style in a direction opposite to a magnetic detection element, and regularly changing an area of the magnetic member opposite to the magnetic detection element along a relative movement direction. SOLUTION: In the case of a rotary potentiometer, the shape of a magnetic member 1a is formed in a substantially spiral style such that it is formed on a substrate 2a of a disk shape along a circle corresponding to locii 3a of relative movement of a magnetic detection element 5 so that each distance (h) between opposite ends on the circle may be equal and changed linearly 3a of relative movement of a magnetic detection element 5. The substrate 2a with such a substantially spiral magnetic member 1a is supported so as to be rotatable with a shaft 4 fixed at an axis thereof, and the magnetic detection element 5 is positioned at a specified interval from the substrate 2a in opposition to the member 1a. The rotary potentiometer is constructed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic potentiometer for detecting a rotation angle amount and a linear movement amount of a measuring instrument, an electric device, an electric machine or the like.

[0002]

2. Description of the Related Art A contact-type potentiometer generally used is a method in which a carbon-based resistive paste is printed on an insulating substrate such as an epoxy resin and then fired and solidified. And a moving contact terminal. In the case of this contact potentiometer, an appropriate lubricant is supplied between the carbon resistor and the contact terminal to reduce the contact resistance, thereby reducing the damage of the carbon resistor surface by the contact terminal.

On the other hand, as a non-contact type potentiometer utilizing a magnetic signal, there is a potentiometer in which a multi-polarized permanent magnet is disposed so as to be relatively movable, facing a magnetic detecting element. In this magnetic potentiometer, the magnetic flux applied to the magnetoresistive element changes due to the rotation or linear movement of the multipolar magnetized permanent magnet, and a sine waveform output is obtained by the change in the magnetic flux. However, in order to perform multi-pole magnetization, it is necessary to alternate the current of the coil in synchronization with the moving magnetic member and alternately magnetize a large number of N poles and S poles, which is extremely troublesome and inefficient. there were.

As a typical example of such a magnetic potentiometer, there is a potentiometer LP-18S commercially available from, for example, Electroacoustics. This LP-18S
Has a multi-pole magnetized permanent magnet at the tip of a non-magnetic shaft, and two magneto-resistive elements are installed at a predetermined angle facing the permanent magnet. An opposing yoke is provided on the back surface of the magnetoresistive element, and a balanced magnetic field is generated by the opposing yoke and the permanent magnet. However, in addition to the need for multipolar magnetization, the shape of the magnetoresistive element has a donut shape and a complex shape with a large number of cuts on the inner and outer sides to ensure high impedance. The processing and installation were extremely complicated.

Further, when a simple Hall element is used as the magnetic detecting element, the Hall element is arranged so as to be sandwiched between the permanent magnet and the yoke in order to obtain a stable sine waveform.
It has been proposed to devise the shape of the yoke, or to arrange the permanent magnet at an angle to the Hall element as described in JP-B-60-41476 and JP-B-60-41477. However, in order to complicate the shape of the yoke or to relatively incline the permanent magnet and the Hall element, complicated component processing is required, and high precision is required for the attachment.

[0006]

As described above, in the contact type potentiometer, since the contact terminals are in contact with the resistor substrate, even if a lubricant or the like is supplied during the contact terminals, the surface of the carbon resistor by the contact terminals is reduced. Is inevitable. For this reason, the surface of the resistor causes electric noise, and the contact potentiometer has a short life.

On the other hand, in the case of a non-contact magnetic potentiometer, troublesome and inefficient multipolar magnetization is required, and
In order to obtain a stable output with high impedance, it was necessary to use a magnetic detecting element having a special shape as described above, or to add special measures to the shape and arrangement of the yoke. However, since the processing accuracy and attachment accuracy of these components greatly affect the accuracy of the output signal, the component processing and assembly processes are complicated to ensure these accuracy, and the complicated multi-pole magnetization process and cost It was a major cause of up.

The present invention has been made in view of such a conventional situation,
There is no need to perform inefficient multipolar magnetization, one magnetization in one direction is sufficient, and a simple magnetic detection element can be used, and output signals corresponding to the rotation angle and linear momentum can be obtained. It is an object of the present invention to provide a magnetic potentiometer that can be stably obtained with high accuracy at a low cost.

[0009]

To achieve the above object, a magnetic potentiometer provided by the present invention comprises: a magnetic detecting element for detecting magnetism generated from a magnetic pole of a magnetic member;
In a magnetic potentiometer including a substrate relatively moving to face the magnetic detection element and a magnetic member provided on the substrate, the magnetic member is unipolarly magnetized in a direction facing the magnetic detection element. Wherein the area of the magnetic member facing the magnetic sensing element changes regularly along the direction of relative movement.

[0010] The magnetic potentiometer of the present invention is
When the object to be detected performs a rotary motion, the substrate and the magnetic detection element are rotated relative to each other. When the object to be detected performs a linear motion, the substrate and the magnetic detection element are moved relative to each other. It can be configured as a linear potentiometer that moves linearly.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic potentiometer according to the present invention is disclosed in an earlier application filed by the same applicant, as disclosed in Japanese Patent Application Laid-Open No.
As in the case of the linear magnetic domain described in Japanese Patent Application Laid-Open No. 3 (1993) -1991, a magnetic member unipolarly magnetized in one direction is used. That is, the magnetic member may be unipolarly magnetized in the direction facing the magnetic detection element. For example, the magnetic member is oriented such that the substrate surface side facing the magnetic detection element has an N pole and the opposite side (substrate back side) has an S pole. It can be magnetized.

Further, the magnetic potentiometer of the present invention is characterized in that the shape of the magnetic member is not constant, and the area facing the magnetic detecting element changes regularly along the direction of relative movement. The shape of the magnetic member whose area opposed to the magnetic detection element changes regularly is such that the distance from the center of the trajectory to both ends of the magnetic member is linear along the trajectory of the relatively moving magnetic detection element. Preferably, it is formed to increase or decrease.

As a specific shape of the magnetic member, in the case of a rotary potentiometer, for example, as shown in FIG. 1, a circle corresponding to a locus 3a of relative movement of a magnetic detecting element is formed on a disk-shaped substrate 2a. (Indicated by the dashed line)
A magnetic member 1a having a shape in which the distance h from the circumference to both ends is equal and changes linearly (hereinafter referred to as a substantially spiral shape) is formed. As shown in FIG. 2, a substrate 2a provided with such a substantially helical magnetic member 1a is rotatably supported by a shaft 4 fixed to the center of the shaft, and a magnetic detection element 5 is disposed opposite the magnetic member 1a. By installing the rotary potentiometer at a predetermined interval from 2a, a rotary potentiometer can be configured.

In the case of a linear potentiometer, for example, as shown in FIG. 3, a straight line (indicated by a one-dot chain line) corresponding to a locus 3b of relative movement of the magnetic detecting element is formed on an elongated plate-like substrate 2b. Along the length, the magnetic member 1b has a shape in which the distance h from the straight line to both ends is equal and linearly changes (hereinafter, referred to as an isosceles triangle). The substrate 2b provided with the isosceles triangular magnetic member 1b is
As shown in FIG. 4, it is supported so as to be linearly movable along its longitudinal direction, and is opposed to the magnetic member 1b.
Is disposed at a predetermined interval from the substrate 2b,
A linear potentiometer is configured.

As a result, in the magnetic potentiometer of the present invention, the facing area of the magnetic members 1a and 1b facing the magnetic detecting element 5 changes with the rotation or linear movement of the substrates 2a and 2b. The magnetic flux density detected by the element 5 also changes continuously. By regularly changing the area of the magnetic members 1a and 1b facing the magnetic detection element 5 so that the change of the magnetic flux density becomes linear, a linear output signal corresponding to the rotation angle amount or the linear movement amount is stabilized. Can be obtained.

As the magnetic detecting element, a known Hall element, a magneto-resistive element, or the like can be used. Moreover, the shape of the magnetic member is formed, for example, in a substantially spiral or isosceles triangular shape as described above, and the change in magnetic flux density detected by the magnetic detection element along with the movement of the magnetic member is also linear, which is complicated. It is not necessary to use a magnetic detecting element having a shape, and accurate detection can be performed using an inexpensive Hall element such as an InSb-based or GaAs-based commercially available element.

The magnetic member provided on the substrate may be formed by embedding a permanent magnet having a predetermined shape in the substrate, since the magnetic member may be formed by monopolar magnetization. However, the magnetic member may be formed into a predetermined shape using a paste-like magnet composition. Bonded magnets are preferred. For example,
The magnet composition is filled in a concave portion having a predetermined shape formed in advance on the substrate, or the magnet composition is printed on the substrate in a predetermined pattern, and then heated and solidified. The magnetic member of a predetermined shape formed on the substrate in this manner is then monopolar magnetized only in the direction facing the magnetic sensing element. For example, the surface of the substrate facing the magnetic sensing element is an N pole and the opposite side is S pole. It only needs to be magnetized to be a pole.

The bond magnet is obtained by binding magnetic powder with a binder resin.
Ordinary magnetic powders such as dFeB, SmFeN, and ferrite can be used alone or in combination of two or more. In particular, by using a bond magnet containing a rare earth element such as an SmCo-based, NdFeB-based, or SmFeN-based, a more accurate potentiometer can be provided. Further, as the substrate, not only a non-magnetic material but also a paramagnetic material other than a ferromagnetic material can be used as in the related art.

[0019]

【Example】Example 1  Polyisobutylene having a molecular weight of 1,000,000 as a binder resin
(Storage modulus G 'value at 20 ° C .: 3 × 10⁶dyne /
cm²) 100 parts by weight of SmCo₅800 magnetic powder
And 1000 parts by weight of toluene.
The mixture was uniformly stirred and mixed using a mixer. The resulting paste-like
The magnet composition was fixed to the shaft 4 as shown in FIG.
Epoxy with outer diameter 40mm x inner diameter 20mm x thickness 1mm
A substantially spiral mark is formed on a disk-shaped substrate 2a made of silicone resin.
After printing and coating, dry and cure at 120 ° C for 3 hours
Was.

Next, the substantially spiral magnetic member 1a is monopolarly magnetized in the axial direction by using a pulse magnetizer, and the substrate front side becomes an N pole and the rear side becomes an S pole in one magnetization operation. Disc-shaped substrate 2 having magnetized substantially spiral magnetic member 1a
a was produced. In addition, the obtained substantially spiral magnetic member 1a
Is on the circumference corresponding to the locus 3a of relative movement of the magnetic sensing element, the distance h from the circumference to both ends changes linearly, and the width 2h is 1 mm at the maximum at one end. The length along the circumference from one end to the other end (the point where the width 2h is zero) is 50 mm.

As shown in FIG. 2, facing the magnetic member 1a of the substrate 2a,
A Hall element (HW-108E manufactured by Asahi Kasei Denshi) with a square mm was arranged so that the distance from the substrate 2a was 0.1 mm, and a magnetic rotary potentiometer was manufactured.

In the obtained magnetic rotary potentiometer, the magnetic detection element 5 composed of a Hall element was driven at a rated voltage and the shaft 4 was rotated.
As shown in the figure, it has been confirmed that the output voltage of the magnetic detection element 5 changes linearly according to the rotation angle.

[0023]Example 2  Same as Example 1 except that NdFeB-based magnetic powder was used
With magnetic powder and binder resin polyisobutylene
A magnet composition comprising toluene as a solvent was prepared. this
As shown in FIG. 3, the magnet composition was 5 mm wide × 30 mm long.
mm x 1 mm thick plate made of epoxy resin
After printing and applying in the form of an isosceles triangle on 2b, 120 ° C
For 3 hours.

Next, the isosceles triangular magnetic member 1b
Is unipolarly magnetized in the axial direction using a pulse magnetizer,
By a single magnetizing operation, a plate-like substrate 2b having an isosceles triangular magnetic member 1b with the substrate front side magnetized to the N pole and the back side magnetized to the S pole was obtained. The obtained isosceles triangular magnetic member 1b is on a straight line corresponding to the locus 3b of the relative movement of the magnetic sensing element, and the distance h from the straight line to both ends changes linearly. , Its width 2h is 1mm at the maximum at one end
And the length along a straight line from one end to the other end (the point where the width 2h is zero) is 30 mm.

As shown in FIG. 4, facing the magnetic member 1b of the substrate 2b, a
A Hall element (HW-108E manufactured by Asahi Kasei Electronics) with a square mm was arranged so that the distance from the substrate 2a was 0.1 mm, to produce a magnetic linear potentiometer.

A magnetic detecting element 5 comprising a Hall element of this magnetic linear potentiometer is driven at a rated voltage,
When the substrate 2b was moved in a linear direction, as shown in FIG. 5, it was confirmed that the output voltage of the magnetic sensing element 5 changed linearly according to the movement distance.

[0027]

According to the present invention, it is not necessary to perform troublesome and inefficient multipolar magnetization, and it is sufficient to perform unipolar magnetization in one direction by one magnetization process, and furthermore, the magnetic detecting element is used. Thus, a magnetic potentiometer that can obtain a linear output signal corresponding to the rotation angle amount and the linear movement amount with high accuracy and stability can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a substrate provided with a substantially spiral magnetic member of the present invention.

FIG. 2 is a schematic side view showing a main part of the rotary potentiometer of the present invention.

FIG. 3 is a schematic plan view showing a substrate provided with an isosceles triangular magnetic member of the present invention.

FIG. 4 is a schematic side view showing a main part of the linear potentiometer of the present invention.

FIG. 5 is a graph showing a relationship between a rotation angle or a moving distance and an output voltage in the potentiometer of the present invention.

[Explanation of symbols]

 1a, 1b Magnetic member 2a, 2b Substrate 3a, 3b Locus of relative movement of magnetic detecting element 4 Shaft 5 Magnetic detecting element

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Claims (5)

[Claims] 1. A magnetic potentiometer comprising: a magnetic detecting element for detecting magnetism generated from a magnetic pole of a magnetic member; a substrate relatively moving to face the magnetic detecting element; and a magnetic member provided on the substrate. In the above, the magnetic member is a permanent magnet that is unipolarly magnetized in a direction facing the magnetic detection element, and an area of the magnetic member facing the magnetic detection element changes regularly along a relative movement direction. A magnetic potentiometer characterized in that: 2. The magnetic potentiometer according to claim 1, wherein said magnetic detecting element is a Hall element. 3. The magnetic potentiometer according to claim 1, wherein the magnetic member is a bonded magnet containing a rare earth element. 4. The magnetic potentiometer according to claim 1, wherein said substrate and said magnetic detecting element are rotary potentiometers which relatively rotate and move. 5. The magnetic potentiometer according to claim 1, wherein the substrate and the magnetic detection element are linear potentiometers that relatively linearly move.