JPH01219611A - Leakage magnetic field type potentiometer - Google Patents

Abstract

PURPOSE:To obtain a meter requiring no electrical adjustment element and excellent in adaptability and preferable for miniaturization, by altering the distribution of the leakage magnetic field within a relative moving range of a closed magnetic path and a magnetic field detection means. CONSTITUTION:Permanent magnets 4, 5 having equal magnetic force are connected to both ends of a pair of plate-shaped magnetic bodies 2, 3 to form a closed magnetic field. Support members 6, 7 are bonded to the permanent magnets 4, 5 in a freely revolvable manner so as to be movable up and down by caps 8, 9. A leakage magnetic field detection unit 11 having a predetermined bridge structure is fixed to the leading end of the reciprocating rod 10 in a support cylinder 1. In this constitution, since the caps 8, 9 are operated while the leakage magnetic field detection unit 11 is held to the reference point at the center of the support cylinder 1 at the time of assembling and adjustment to move the permanent magnets 4, 5 up and down to adjust a zero point, an electrical adjustment element is made unnecessary and physical quantity can be accurately detected.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a potentiometer using a permanent magnet and a magnetic field strength detector, and in particular, to a potentiometer that uses a permanent magnet and a magnetic field strength detector. This invention relates to a leakage magnetic field type potentiometer to be used.

(Prior Art) Potentiometers that utilize the radiated magnetic field of a permanent magnet have been introduced for some time, but due to the large attenuation of the radiated magnetic field, their detection range is extremely small and their applications are limited.

In order to solve this kind of problem, the present applicant et al.
Invented a leakage magnetic field type potentiometer that combines a permanent magnet with a closed magnetic path and utilizes the leakage magnetic field of the closed magnetic path, and filed an application earlier.
(Japanese Patent Application Laid-Open No. 62-63811).

To specifically explain one example of the disclosed content, a closed magnetic path is constructed by coupling permanent magnets with equal magnetic force to both ends of a pair of parallel flat magnetic bodies, and a movable magnetic field is formed inside the closed magnetic path. This is a potentiometer equipped with a detection element. Each flat magnetic body effectively propagates the magnetism of the permanent magnet in the direction in which it extends, and a leakage magnetic field is generated between them.

In other words, by utilizing this leakage magnetic field, the detectable range of the magnetic detection element has been dramatically expanded, and the practicality of the magnetic potentiometer has been improved.

(Problem to be Solved by the Invention) By the way, since a potentiometer detects physical quantities such as position, distance, and angle as electrical signals, this leakage magnetic field type potentiometer also has a detection range standard and electrical It is preferable that the standards match.

For example, in the above-mentioned prior application, two sets of magnetic detection elements with different polarities are configured as a bridge, and the midpoint potential of each is differentially amplified. In the distance series going forward, the output gradually attenuates to zero, and as it goes further, the polarity is reversed and gradually increases, but in order to increase its versatility as a potentiometer, this output should be set to zero. The point and physically set standards,
For example, it is important that the midpoint of the detection range coincides with the center point of the detection range.

However, it is difficult to strictly pursue the balance and uniformity of each permanent magnet and each magnetic body, and it is not immediately possible to match the electrical standard with the physical standard.

Therefore, in the above-mentioned prior application, an attempt was made to match each standard by finely adjusting the reference potential in differential amplification using a variable resistor. Although a sufficient effect was obtained by this, a new problem arose when integrating the magnetic detection element and the differential amplifier.

In other words, in order to shift the electrical standard to match the physical standard, it is necessary to make adjustments while monitoring the physical quantity, and for this reason, a signal line for WR adjustment is added, and a variable resistor, Alternatively, it became necessary to separately provide this type of IIA means.

This is a major disadvantage when considering the potentiometer simply as a means for detecting physical quantities such as position, distance, and angle.

In other words, the provision of signal lines and adjustment elements unrelated to the detection of a desired physical quantity imposes restrictions on the application or miniaturization of potentiometers.

SUMMARY OF THE INVENTION An object of the present invention is to provide a leakage magnetic field type potentiometer that does not require an electrical adjustment element, has excellent regression properties, and is advantageous for miniaturization.

(Structure of the Invention) (Means for Solving Problem 11) In order to achieve the above object, in the present invention, a closed magnetic path made of a permanent magnet and a magnetic body and a magnetic field strength detection means are relatively movable. ; In a leakage magnetic field type potentiometer that supports and detects the magnetic field strength of the leakage magnetic field of the closed magnetic circuit,
The structure includes an adjusting means for changing the distribution of the leakage magnetic field within a relative movement range between the closed magnetic path and the magnetic field strength detecting means.

(Function) A change in the distribution of the leakage magnetic field within the relative movement range of the closed magnetic path and the magnetic field strength detection means means a change in the detection conditions of the magnetic field strength detection means, and as a result, the output of the magnetic field strength detection means changes. Certain electrical signals can be shifted. This change in the distribution of the leakage magnetic field is brought about by physical processing such as changing the connection position between the permanent magnet and the magnetic body or the support position of the magnetic field strength detection means, so that no electrical adjustment element is required.

In other words, there are no signal lines or adjustment elements that are unrelated to the detection of physical quantities such as position, distance, or angle, resulting in a leakage field type potentiometer that has excellent regression properties and is advantageous for miniaturization.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

(Example) FIG. 1 is a longitudinal cross-sectional view of a direct-acting leakage field type potentiometer that embodies the present invention as an example.

In FIG. 1, reference numeral 1 denotes a support cylinder made of a non-magnetic material, and inside thereof a pair of flat magnetic plates 2 and 3 are supported in parallel. Perforated rectangular permanent magnets 4 and 5 having approximately equal magnetic force are magnetically coupled to both ends of the flat magnetic plates 2 and 3, respectively.

A hollow support member 6 or 7 is rotatably engaged in the hole of each permanent magnet, and these support members are connected to the support cylinder 1.
It is fixed to caps 8 or 9 screwed onto the upper and lower ends of the. That is, the permanent magnet 4 moves up and down as the cap 8 moves up and down as it rotates, and the permanent magnet 5 moves up and down as the cap 9 moves up and down as it rotates.

The cap 8 is ring-shaped, and a reciprocating rod 10 made of a non-magnetic pipe passes through it.

The reciprocating iron 10 further extends inwardly through the support member 6, and has a leakage magnetic field detection unit 11 fixed to its tip.

The leakage magnetic field detection unit 11 includes a magnetoresistive bridge 12, a differential amplifier 13, and a filter 14, as shown in FIG.
It becomes more. The magnetoresistive bridge 12 includes four bridge-connected magnetoresistive elements 12a.

12b, 12c and 12d, the magnetoresistive element 12
The connection point between a and 12c is at the reference potential Vc, and the connection point between 12b and 12c is at the reference potential Vc.
The connection point with d is connected to ground GND. Although each magnetoresistive element is arranged in the same horizontal plane, the direction of action of the leakage magnetic field is opposite between the magnetoresistive elements 12a and 12b and 12c and 12d. In other words, the magnetoresistive element 1
The potential difference between the connection point between 2a and 12b and the connection point between 12c and 12d is twice the amount of change in each pair.

After this potential difference is amplified by the differential amplifier 13, minute fluctuations are removed by the filter 14 at the next stage and output as the detected potential signal VP.

These magnetoresistive bridge 12, differential amplifier 13, and filter 14 are made into a hybrid IC and molded with resin. There are three signal lines, one for constant voltage Vc, one for GND, and one for detected potential signal VP, which pass through the reciprocating condo 10 and exit to the outside.

The reference point of this potentiometer is the midpoint of the support cylinder 1. When the detected potential signal Vp at this reference point does not become zero in the assembled state, the permanent magnets 4 and 5 are screwed in or unscrewed while keeping the detection position of the leakage magnetic field detection unit 11 at the reference point. Move it up and down to adjust the zero point. As a result, the gaps a1 and a2 between each cap 8, 9 and the supporting cylinder 1. That is, permanent magnet 4
The distance b1 from the permanent magnet 5 to the reference point is not necessarily equal to the distance b2 from the permanent magnet 5 to the reference point.

After the zero point adjustment is completed, the gaps between the caps 8 and 9 and the support cylinder 1 are fixed with resin, and a magnetic sheath for magnetic shielding is applied to the outside.

Next, a second embodiment will be explained.

FIG. 2a is a longitudinal cross-sectional view of the rotary leakage magnetic field type potentiometer, and FIG. 2b is a partial view of the cross-section taken along the line IIB-IIB.

This potentiometer detects the rotation angle of the rotation shaft 20.

The rotating shaft 20 is made of a non-magnetic material and is rotatably engaged with a magnetic housing 21 . A non-magnetic bracket 22 is fixed inside the housing 21, and the bracket 22 supports a permanent magnet 23 and a magnetic ring 24. The permanent magnet 23 and the magnetic ring 24 constitute a ring concentric with the rotating shaft 20. These are fixed to the bracket 22 by being sandwiched between fixing members 25, which are also made of non-magnetic material.

A magnetic disc 26 for improving the magnetic field is screwed onto the tip of the shaft 20.

The leakage magnetic field detection unit 27, as shown in FIG.
Consists of 4. An insulating substrate 28 to which this unit 27 is fixed
is screwed onto a magnetic cap 29 rotatably engaged with the housing 21. A round hole is bored in the cap 29, and three signal lines connected to the leakage magnetic field detection unit 27' exit from the hole.

By the way, the rotation of the rotation shaft 20 is controlled by the bracket 22.
In this embodiment, the center of this rotation range is used as the reference of this potentiometer. Due to the non-uniformity of the body ring 24, the leakage magnetic field detection unit 2
7 does not necessarily detect the zero point. In that case, while keeping the shaft 20 as a reference, the leakage magnetic field detection unit 27,
The insulating substrate 28 and the cap 29 are rotated together to adjust the zero point. As a result, the leakage magnetic field detection unit 27 rotates by an arbitrary angle c1 or c2 from the reference.

After completing the zero point adjustment, the end of the housing 21 is caulked to fix the cap 29. In addition, the housing 21
And the cap 29 constitutes a magnetic shield.

〔Effect of the invention〕

As explained above, in the present invention, the detection conditions of the magnetic field strength detecting means are physically changed by means of changing the distribution of the leakage magnetic field within the relative movement range of the closed magnetic path and the magnetic field strength detecting means, Since the output electrical signal is shifted, electrical adjustment elements are not required. As a result, as shown in the explanation of the embodiment, there is no need for signal lines or adjustment elements unrelated to the detection of physical quantities such as position, distance, or angle, and it is possible to obtain a leakage magnetic field type potentiometer that has excellent decrementability and is advantageous for miniaturization. .

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a direct-acting leakage magnetic field type potentiometer of the first embodiment -0 Fig. 2a is a longitudinal cross-sectional view of a rotary leakage magnetic field type potentiometer of the second embodiment, and Fig. 2b is It is a partial view of the cross section taken along the line ■B-■B. FIG. 3 is a block diagram showing the configuration of a leakage magnetic field detection unit common to the first and second embodiments. 1: Support cylinder 2, 3: Flat magnetic plate 4.5
: Permanent magnet 6, 7: Support member 8.9: Cap 10: Reciprocating rod 11: Leakage magnetic field detection unit 12: 12: Magnetic resistance bridge 13: Differential amplification amount 14: Filter 20: Rotating shaft 21: Housing 22 nib bracket
23: Permanent magnet 24: Magnetic ring 25: Fixed member 26: Magnetic disk for improving magnetic field 27: Leakage magnetic field detection unit 28: Insulating substrate 29: Cap 4.5, 23
: (Permanent magnet) 2, 3, 24 : (Magnetic material) 11.27: (Magnetic field strength detection means) 1.8, 10.21, 22, 25.2 &, 29 : (
Supporting means) 8.9.21, 28, 29: (Adjusting means) Figure 2a Figure 2b

Claims (1)

[Scope of Claims] A permanent magnet; A magnetic body that is magnetically connected to the permanent magnet and forms a closed magnetic path; A magnetic field intensity detection means that is provided within the leakage magnetic field of the closed magnetic path and detects the magnetic field intensity of the leakage magnetic field; Supporting means for supporting the closed magnetic path and the magnetic field strength detection means in a relatively movable manner; and changing the distribution of the leakage magnetic field within a relative movement range of the closed magnetic path and the magnetic field strength detection means. A leakage magnetic field type potentiometer comprising adjustment means;