JP3186258B2 - Non-contact potentiometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a potentiometer for obtaining an electrical output signal corresponding to, for example, a rotation angle, and more particularly to a non-contact type potentiometer using a ferromagnetic resistance element and a magnet. About.

[0002]

2. Description of the Related Art Generally, a potentiometer has a slider contacting a resistor pattern having a DC power supply connected to both ends thereof.
It is configured as a sliding resistance type that outputs a voltage signal corresponding to the contact position of the slider. However, such a sliding resistance type potentiometer has a structure in which the slider is always in contact with the resistor pattern and is moved.
The resistor is damaged by wear due to contact with the slider, and has a problem in reliability.

In order to solve such a problem of the sliding contact type, a non-contact type potentiometer using a magnetoresistive element has been considered as disclosed in, for example, Japanese Patent Publication No. 63-56713. In this non-contact potentiometer, a permanent magnet is opposed to a resistor pattern formed of a ferromagnetic material at small intervals, and the resistance value of the resistor pattern at a position opposed to the permanent magnet is changed. ,
An electrical output corresponding to the position of the permanent magnet is obtained.

[0004] It utilizes the property that the resistance value of a magnetic resistor changes in proportion to the applied magnetic field strength. Therefore, in order to stabilize the output as a potentiometer, this property is used together with the magnetic field strength of a permanent magnet. It is necessary to strictly control the mounting position of the permanent magnet. For this reason, there is a significant factor in cost increase that complicates the assembly process management.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been sufficiently developed even in the case where a resistor pattern formed of a ferromagnetic thin film and a permanent magnet are used. It is an object of the present invention to provide a highly reliable non-contact potentiometer which has a structure which can be easily constructed and can be easily assembled, and which can surely improve output stability and production yield. .

[0006]

SUMMARY OF THE INVENTION A non-contact potentiometer according to the present invention has a resistor pattern formed of a strip-shaped magnetoresistive thin film having a width which sequentially changes from one end to the other end. Is formed on an insulating substrate, and the width of the resistor pattern is formed on a holder holding member made of a non-magnetic material which is moved in accordance with the operation amount of the measured object along the longitudinal direction of the resistor pattern. A permanent magnet magnetized in the direction is held, and this permanent magnet is opposed to the resistor pattern at a small interval.

In addition, two resistor patterns are arranged side by side so that the direction of change in width is reversed, and one arm of a bridge circuit is constituted by the two resistor patterns. It also includes doing.

[0008]

In the non-contact potentiometer constructed as described above, the permanent magnet is moved along the resistor pattern in accordance with the operation of the object to be measured, and the magnetic field generated by the permanent magnet acts to reduce the resistance. The position of the resistor pattern where the value changes moves. Here, the width of the resistor pattern changes depending on its position. Therefore, the resistance value between both ends of the resistor pattern is variably set in accordance with the position of the permanent magnet, that is, the operating position of the device under test. The operating position of the device under test is recognized by the voltage signal corresponding to the resistance value. Also, if the resistor pattern is 2
If a pair is set and one arm of the bridge circuit is constituted by the resistance elements of the two sets of resistor patterns, a voltage output corresponding to the position of the permanent magnet can be obtained at the output of the bridge circuit.

In such a potentiometer, the resistance value at a specified position of the resistor pattern is changed by a magnetic field generated by a permanent magnet, and a change in resistance value according to the operating position of the magnetic field is obtained. . in this case,
The permanent magnet is set to face the resistor pattern at a small interval, and it is sufficient that the magnetic field strength equal to or higher than the saturation magnetic field is applied to the resistor pattern by the permanent magnet. There is no need to strictly manage the relationship, and a highly reliable potentiometer can be obtained.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a non-contact potentiometer, in which a ferromagnetic resistive material is deposited on the surface of an insulating substrate 11 to form a ferromagnetic thin film, and the ferromagnetic thin film is etched using a predetermined mask or the like. By doing so, the resistor pattern 12 is formed. The resistor pattern 12 is formed in a strip shape substantially along an arc, and the width of the resistor pattern gradually increases from one end to the other end. ing. Then, electrodes 13 and 14 are formed at both ends of the resistor pattern 12, respectively.

A rotary shaft 15 made of a non-magnetic material is set at a portion corresponding to the center of the substantially arc-shaped resistor pattern 12. Although not shown in detail, the rotating shaft 15 is coupled to the object to be measured, and is rotated in accordance with the operation of the object to be measured. Provided holding body 16 is provided. The holder 16 is set at a small interval to face the surface of the substrate 11 on which the resistor pattern 12 is formed, and a rectangular parallelepiped permanent magnet 17 is attached to the holder 16 by bonding or the like.

In this case, the magnetic poles of the permanent magnet are set so that a magnetic field is set in a direction crossing the resistor pattern 12 in the width direction thereof.
The resistance value of the portion facing 17 is set to a low value. Here, the width of the resistor pattern 12 is different depending on the portion, and the width gradually changes from one side to the other side, and therefore, corresponds to the width of the portion where the resistance value is reduced by the permanent magnet 17. Then, the resistance value between the electrodes 13 and 14 changes, and a correlation is set between the resistance value and the position of the permanent magnet 17, that is, the operating position of the measured object.

FIG. 2 shows a state where such a potentiometer is actually assembled. A bearing 22 constituted by a ball bearing is formed in a portion corresponding to a case 21. The holder 16 is rotatably held in the case 21 by passing through the case 21. Wiring board is attached to the bottom plate 211 of this case 21
23 are set, and the electrodes 13 and 14 on the substrate 11 are connected to the lead wires 24 led out of the case 21 through the circuit on the wiring board 23.
To be connected to

In this manner, the insulating substrate 11 having the resistor pattern 12 formed on the surface of the wiring board 23 is held and set. The surface of the substrate 11 and the holder 16 are opposed at a small interval. Is set. The permanent magnet 17 is fitted into a recess formed on the surface of the holding body 16 facing the substrate 11, and is fixed and held using an adhesive or the like.

In the non-contact potentiometer constructed as described above, when the permanent magnet 17 moves along the resistor pattern 12 with the rotation of the rotating shaft 15, the resistor pattern 12
The resistance value of the portion opposed to the permanent magnet 17 is reduced. In this case, since the width of the resistor pattern 12 is different depending on the part, the resistance value between the electrodes 13 and 14 of the resistor pattern 12 changes according to the rotation angle of the rotating shaft 15, and the resistance value changes. A corresponding electrical signal is detected.

FIG. 3 shows the rotation angle of the rotating shaft 15 and the electrodes 13 and 14.
A predetermined constant current is passed between the electrodes 13 and 14, and the potential difference between the electrodes 13 and 14 is measured to determine the rotation angle of the rotating shaft 15. That is, the movement amount of the measured object can be measured.

In this embodiment, the resistor pattern
Although 12 is formed in the shape of an arc centered on the rotation shaft 15, it may be formed in a polygonal shape by a combination of straight lines set corresponding to this arc. Also,
The resistor pattern can also be formed by a linear strip-like pattern whose width changes sequentially from one end to the other end. In this case, the permanent magnet held by the holder is It is configured to be moved linearly along the body pattern.

FIG. 4 shows a second embodiment, in which first and second resistor patterns 121 and 122 of an arc-shaped ferromagnetic thin film as shown in FIG.
Is formed.

The first and second resistor patterns 121
And 122 are formed concentrically about the rotation axis 15, and one end of the first resistor pattern 121 is connected to the electrode 25, and the width thereof is sequentially increased from the electrode 25. Connected to the electrode 26. The electrode 26 is connected in common to the end of a second resistor pattern 122 which is set concentrically. The width of the second resistor pattern 122 gradually increases from the connection portion of the electrode 26. And is connected to an electrode 27 formed at the other end side by side with the electrode 25.

That is, the first and second resistor patterns 121 and 122 are connected in series by the electrode 26, and the permanent magnet 17 attached to the holding body 16 integrated with the rotating shaft 15 is in a parallel state. The magnetic field generated by the permanent magnet 17 is set so as to commonly straddle the first and second resistor patterns 121 and 122 to be set.
Are set in a direction intersecting the resistor patterns 121 and 122 of FIG.

Here, the first and second resistor patterns
Reference numerals 121 and 122 are set so as to constitute one arm of the bridge circuit.
And 122 are connected in parallel with the other two series circuits of fixed resistors, a DC power supply is connected between the electrodes 15 and 27, and an output signal is taken from the electrode 26. Specifically, the electrode 25 is connected to the constant voltage power supply Vcc, the electrode 27 is grounded (GND), and the output Vout
Is taken out.

In the potentiometer thus configured, the position of the permanent magnet 17 changes on the resistor patterns 121 and 122 with the rotation of the rotating shaft 15, and the position of the permanent magnet 17 The resistance value between both terminals changes continuously. In this case, the first and second
In each of the resistor patterns 121 and 122, the direction of change in the width of the pattern is opposite to the direction of movement of the permanent magnet 17, so that the first and The resistance values of the second resistor patterns 121 and 122 change at opposite slopes.

The resistor patterns 121 and 122 constitute one arm of a bridge circuit, and the resistance values between Vcc and GND of the bridge circuit and the output Vout change in directions opposite to each other. Therefore, the output voltage Vout from the bridge circuit changes linearly as shown in FIG. 5 in accordance with the change in the rotation angle of the rotary shaft 16.

In the embodiment shown in FIGS. 1 and 4,
The resistance value of each of the resistor patterns 12, 121, 122 decreases with an increase in the magnetic field intensity applied by the permanent magnet 17. However, in such a decrease in resistance value change,
When a magnetic field equal to or higher than the saturation magnetic field is applied to the resistor pattern, the resistance value of the resistor pattern does not decrease more than when the saturation magnetic field is applied, and becomes a constant value thereafter.

Therefore, considering the mounting tolerance between the rectangular parallelepiped permanent magnet 17 and the magnetoresistive patterns 12 and 121 and 122 and the variation in the magnetizing strength of the permanent magnet 17, these mounting tolerances and the variation in the magnetizing strength are considered. Even if it is present, a stable output can always be obtained if the mounting mode of the permanent magnet 17 is designed so that a magnetic field of a saturation magnetic field strength or more is applied to the resistor patterns 12, 121, 122.

[0026]

As described above, according to the non-contact type potentiometer according to the present invention, the resistor pattern constituting the magnetoresistive element made of the ferromagnetic material and the permanent magnet moved corresponding to the operation of the measured object As a result, a stable and reliable output can be obtained irrespective of the mounting tolerance and the like, and a highly reliable non-contact potentiometer with sufficient stability and improved yield can be obtained.

[Brief description of the drawings]

FIG. 1A is a diagram showing a configuration of a non-contact potentiometer according to one embodiment of the present invention viewed from a plane, and FIG. 1B is a cross-sectional view taken along line bb of FIG. 1A.

FIG. 2 is a sectional view showing an assembling configuration of the potentiometer.

FIG. 3 is a diagram showing a state of a resistance value change of the potentiometer.

FIG. 4A is a diagram showing a configuration of a non-contact potentiometer according to another embodiment of the present invention viewed from a plane, and FIG.
FIG. 3 is a sectional view taken along line bb of FIG.

FIG. 5 is a diagram showing output characteristics of the potentiometer.

[Explanation of symbols]

11 ... insulating substrate, 12, 121, 122 ... resistor pattern, 13,
14, 25 to 27: Electrode, 15: Rotary shaft, 16: Holder, 17: Permanent magnet.

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 43/02 G01B 7/30 101 H01C 10/00 JICST file (JOIS)

Claims (3)

(57) [Claims] A resistive element pattern formed on an insulating substrate, the resistive element pattern comprising a magnetoresistive thin film formed in a strip-like pattern having a width that sequentially changes from one end to the other end; A holder made of a non-magnetic material that is moved along the longitudinal direction of the resistor pattern in accordance with the amount of movement of the body, and attached to the holder so as to face the resistor pattern at a small interval. A permanent magnet magnetized in the width direction of the resistor pattern, wherein the permanent magnet is magnetized so that a saturation magnetic field can be applied to the resistor pattern. Contact potentiometer. And a first resistor pattern formed on the insulating substrate, the first resistor pattern comprising a magnetoresistive thin film formed in a strip-like pattern having a width which is sequentially different from one end to the other end. The first resistor pattern is formed in parallel with the first resistor pattern.
A second resistor pattern composed of a magnetoresistive thin film formed in a strip-like pattern having a width sequentially different in a direction opposite to that of the resistor pattern, and a movement amount of the object to be measured. A holding member made of a non-magnetic material moved along the longitudinal direction of the resistor pattern; and the two resistor patterns straddling the holding member in common with the first and second resistor patterns. And a permanent magnet that is attached so as to be opposed to each other at a small interval in the width direction of the two resistor patterns, and is magnetized with a magnetization strength such that a saturation magnetic field is applied to the resistor patterns. A non-contact potentiometer, wherein one arm of a bridge circuit is constituted by the first and second resistor patterns. 3. The resistive element pattern is formed so as to correspond to an arc corresponding to one center, and a rotation axis that is rotated in accordance with an operation amount of the object to be measured is set at the one center. 3. The non-conductive device according to claim 1, wherein the holding member is rotated with the rotation of the rotation shaft, and the permanent magnet is moved along the resistor pattern in a contacted manner. Contact potentiometer.