JP2000221084A - Distortion detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distortion detection device not allowing fluctuation of an output caused by the ambient temperature change to have a stable characteristic. SOLUTION: This distortion detection device is provided with at least two first element parts 24 on a surface of an insulation substrate 22, while the first element part 24 comprises both a first distortion resistance element 25 and a temperature characteristic adjustment resistor 26 connected in series with the first distortion resistance element 25, having a resistance temperature coefficient different from the first distortion resistance element 25. By adjusting a resistance value of the temperature characteristic adjustment resistor 26 in the first element part 24, temperature characteristics of two outputs in a bridge circuit are almost equalized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain detector for detecting a strain generated by a weight, a force, an acceleration, and a minute displacement used in an automobile or various industrial machines.

[0002]

2. Description of the Related Art As a conventional distortion detecting apparatus of this type, one disclosed in Japanese Patent Application Laid-Open No. 8-29273 is known.

Hereinafter, a conventional distortion detecting device will be described with reference to the drawings.

FIG. 7 is a perspective view of a conventional distortion detecting device, and FIG. 8 is a circuit diagram of the distortion detecting device.

In FIGS. 7 and 8, reference numeral 1 denotes a fixed base.
An insulating substrate 2 has one end fixed to the fixed base 1. Reference numeral 3 denotes a weight member, and the weight member 3 is fixed to the other end of the insulating substrate 2. Reference numeral 4 denotes a strain resistance element. The strain resistance element 4 is provided on the surface of the insulating substrate 2 and has one end electrically connected to a power supply terminal 5. Reference numeral 6 denotes a first bias resistor. The first bias resistor 6 is provided on the surface of the insulating substrate 2.
One end is connected to the other end of the strain resistance element 4 and the first output terminal 7.
And the other end is electrically connected to the GND terminal 8. Reference numeral 9 denotes a second bias resistor. The second bias resistor 9 has one end electrically connected to the power supply terminal 5 and the other end electrically connected to the second output terminal 10. Reference numeral 11 denotes a third bias resistor. The third bias resistor 11 has one end electrically connected to the second output terminal 10 and the other end electrically connected to the GND terminal 8. Then, the strain resistance element 4, the first
, The second bias resistor 9 and the third bias resistor 11 constitute a bridge circuit.

Next, the operation of the conventional distortion detecting device having the above-described configuration will be described.

When an external force acts on the weight member 3 due to, for example, acceleration, the insulating substrate 2 is deformed by the external force.
In this case, the strain resistance element 4 is provided on the surface of the insulating substrate 2, and the resistance value of the strain resistance element 4 changes in proportion to the deformation amount of the insulating substrate 2. And the strain resistance element 4,
Since the first bias resistor 6, the second bias resistor 9, and the third bias resistor 11 form a bridge circuit, the first output terminal 7 and the second output terminal 10
The external force applied to the weight member 3 is detected based on the voltage difference.

Here, considering the case where the temperature around the conventional strain detecting device changes, the output change rate A due to the temperature change of the first output terminal 7 in the conventional strain detecting device is expressed by the following equation.

[0009]

(Equation 1)

## EQU1 ## Also, the second output terminal 10
Output change rate B due to temperature change is

[0011]

(Equation 2)

## EQU1 ##

In order to prevent the output of the conventional strain detecting device from fluctuating due to a change in ambient temperature, the output change rate A due to a change in the temperature of the first output terminal 7 is determined by the temperature of the second output terminal 10. It was necessary to make the output change rate B substantially equal to the change.

[0014]

However, in the above-described conventional configuration, in order to prevent the output from fluctuating due to a change in ambient temperature, the output change rate A due to a change in the temperature of the first output terminal 7 must be set to the first value. It is necessary to make the output change rate B substantially equal to the output change rate B due to the temperature change of the output terminal 10
In this case, the strain resistance element 4, the first bias resistor 6, the second
Although the resistance value and the temperature coefficient value of the bias resistor 9 and the third bias resistor 11 must be accurately manufactured, the strain resistance element 4, the first bias resistor 6, the second bias resistor 9, and the third It is difficult to manufacture the resistance value and the temperature coefficient value of the bias resistor 11 with high accuracy, and it is difficult to provide a distortion detecting device whose output does not fluctuate due to a change in ambient temperature. Was.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a distortion detecting device having stable characteristics without an output fluctuating due to a change in ambient temperature.

[0016]

In order to achieve the above object, a strain detecting apparatus according to the present invention comprises an insulating substrate made of an elastic material, a first strain resistance element provided on the surface of the insulating substrate, and a first strain resistance element. At least two first element portions connected in series to the first strain resistance element and having a temperature characteristic adjustment resistor having a temperature coefficient of resistance different from that of the first strain resistance element; and a surface of the insulating substrate. And at most two second element sections each including a second strain resistance element connected in series to the first element section.
By forming a bridge circuit composed of four element sections by one first element section and at most two second element sections, and adjusting a resistance value of a temperature characteristic adjusting resistor in the first element section, 2 in the bridge circuit
The temperature characteristics of the two outputs are made approximately equal.
According to this configuration, the output does not fluctuate due to a change in ambient temperature, and a distortion detecting device with stable characteristics can be provided.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an insulating substrate made of an elastic material, a first strain resistance element provided on the surface of the insulating substrate, and a first strain resistance element. At least two first element portions connected in series to the element and including a temperature characteristic adjustment resistor having a temperature coefficient of resistance different from the temperature coefficient of resistance of the first strain resistance element, and provided on the surface of the insulating substrate; At least two second element sections each including a second strain resistance element connected in series to the first element section, and the at least two first element sections and at most two second element sections. A bridge circuit composed of four element sections is constituted by the element sections, and the temperature characteristics of the two outputs in the bridge circuit are made substantially equal by adjusting the resistance value of the temperature characteristic adjusting resistor in the first element section. West According to this configuration, on the surface of the insulating substrate, a first distortion resistance element and a resistance temperature coefficient connected in series with the first distortion resistance element are equal to the resistance temperature coefficient of the first distortion resistance element. Providing at least two first element portions each having a different temperature characteristic resistance;
Since the temperature characteristics of the two outputs in the bridge circuit are made substantially equal by adjusting the resistance value of the temperature characteristic adjusting resistor in the element portion of the above, even if there is a change in the ambient temperature, the two outputs in the bridge circuit are not changed. This has the effect that the output change rates due to the temperature change of the output terminals can be easily made substantially equal to each other.

According to a second aspect of the present invention, the resistance value of the first strain resistance element in the first element portion according to the first aspect is set to be at least ten times the resistance value of the temperature characteristic adjusting resistor, The absolute value of the temperature coefficient of resistance of the first strain resistance element is set to be equal to or less than 0.1 times the absolute value of the temperature coefficient of resistance of the temperature characteristic adjustment resistor. , The resistance value of the first strain resistance element is set to 10 times or more the resistance value of the temperature characteristic adjustment resistance, and the absolute value of the resistance temperature coefficient of the first strain resistance element is set to the resistance temperature of the temperature characteristic adjustment resistance. Since the absolute value of the coefficient is set to 0.1 times or less, even if the resistance value of the temperature characteristic adjusting resistor is adjusted, the combined resistance of the first element portion is hard to change, thereby, One out Even if the output change rates due to the temperature change of the terminals become substantially equal to each other, the combined resistance of the first element portion hardly changes, so that the output does not fluctuate due to a change in the ambient temperature and the external force to be measured is not changed. Is zero and the output voltages of the two output terminals at the initial temperature can be made substantially equal to each other.

According to a third aspect of the present invention, there is provided an insulating substrate made of an elastic material, provided on a surface of the insulating substrate, connected to the first strain resistance element and connected in parallel to the first strain resistance element. A temperature coefficient adjusting resistor having a temperature coefficient different from a temperature coefficient of resistance of the first strain resistance element, at least two first element sections provided on a surface of the insulating substrate, and a first element section; At least two second element sections comprising a second strain resistance element connected in series, wherein at least two first element sections and at most two second element sections are provided.
By forming a bridge circuit composed of four element sections by the element section, and adjusting the resistance value of the temperature characteristic adjusting resistor in the first element section, the temperature characteristics of two outputs in the bridge circuit become substantially equal. According to this configuration, the first surface is provided on the surface of the insulating substrate.
And at least two first element sections, which are connected in parallel with the first distortion resistance element and have a temperature characteristic adjustment resistance different from the resistance temperature coefficient of the first distortion resistance element. In addition, since the temperature characteristics of the two outputs in the bridge circuit are made substantially equal by adjusting the resistance value of the temperature characteristic adjusting resistor in the first element portion, even if there is a change in the ambient temperature, This has the effect that the output change rates due to the temperature change of the two output terminals in the bridge circuit can be easily made substantially equal to each other.

Hereinafter, a distortion detecting apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a distortion detecting device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of the distortion detecting device.

In FIGS. 1 and 2, reference numeral 21 denotes a pair of fixing bases made of resin or metal. Reference numeral 22 denotes an insulating substrate made of an elastic material.
1 are fixed to both ends of the back surface. Also, this insulating substrate 2
Numeral 2 is constituted by providing an insulating glass layer (not shown) on the upper surface of a base material (not shown) such as stainless steel. Reference numeral 23 denotes a weight member, which is provided so as to protrude outward from substantially the center of the back surface of the insulating substrate 22. Reference numeral 24 denotes a pair of first element parts, each of which is provided on the surface of the insulating substrate 22 and has a first strain resistance element 25.
Connected to the first strain resistance element 25 in series by the circuit pattern 22a and having a temperature coefficient of resistance of the first strain resistance element 2
5 and a temperature characteristic adjusting resistor 26 which is different from that of FIG. One end of the temperature characteristic adjusting resistor 26 in the first element section 24 is electrically connected to a power terminal 27. The first strain resistance element 25 in the first element section 24 has one end electrically connected to the other end of the temperature characteristic adjustment resistor 26 and the other end electrically connected to a pair of output terminals 28. Connected to Further, the resistance value of the first strain resistance element 25 in the first element section 24 is set to be 10 times or more the resistance value of the temperature characteristic adjustment resistance 26, and the resistance temperature coefficient of the first strain resistance element 25 is reduced. The absolute value is set to be equal to or less than 0.1 times the absolute value of the temperature coefficient of resistance of the temperature characteristic adjusting resistor 26. Reference numeral 29 denotes a pair of second element sections. The pair of second element sections 29 are provided on the surface of the insulating substrate 22, respectively, and the other of the first strain resistance elements 25 in the first element section 24. The second distortion resistance element 30 has one end electrically connected to the pair of output terminals 28 and the other end connected to GN.
It is electrically connected to the D terminal 31. And the first
The element section 24 and the second element section 29 constitute a bridge circuit composed of four element sections.

Next, a method of assembling the distortion detecting apparatus according to the embodiment of the present invention configured as described above will be described.

First, after printing a glass paste (not shown) on a metal base material (not shown) prepared in advance,
Baking is performed at about 850 ° C. for about 45 minutes to form the insulating substrate 22.

Next, a metal glaze-based carbon paste is printed on the surface of the insulating
After baking at 50 ° C. for about 45 minutes, a first strain resistance element 25 and a temperature characteristic adjustment resistance 26 are formed on the insulating substrate 22.
Is formed, and a second element section 29 including the second strain resistance element 30 is formed.

Next, a silver paste is printed on the surface of the insulating substrate 22 and baked at about 850 ° C. for about 45 minutes.
The resistance element 25 and the temperature characteristic adjustment resistance 26
The power supply terminal 2 is connected to the insulating substrate 22 so as to be electrically connected to the second strain resistance element 30 in the element portion 29 of FIG.
7. A pair of output terminals 28, a GND terminal 31, and a circuit pattern 22a are formed.

Next, after fixing a pair of fixing bases 21 to both ends of the back surface of the insulating substrate 22, a weight member 23 is fixed so as to protrude outward from substantially the center of the back surface of the insulating substrate 22.

Finally, the power supply terminal 27 is connected to a power supply (not shown) to apply a voltage,
The temperature characteristic adjusting resistor 26 is trimmed so that the ambient temperature of the insulating substrate 22 is varied and the output change rates due to the temperature change of the pair of output terminals 28 are substantially equal to each other.

Next, the operation of the distortion detecting apparatus having the above-described configuration according to the embodiment of the present invention will be described.

When an external force acts on the weight member 23 due to, for example, acceleration or the like, the external force deforms the insulating substrate 22. In this case, since a pair of first strain resistance elements 25 and a pair of second strain resistance elements 30 are provided on the surface of the insulating substrate 22, the pair of first strain resistance elements 25 and the pair of second strain resistance elements 30 are proportional to the amount of deformation of the insulating substrate 22. The resistance values of one strain resistance element 25 and a pair of second strain resistance elements 30 change. Since a bridge circuit is formed by the pair of first strain resistance elements 25 and the pair of second strain resistance elements 30, an external force applied to the weight member 23 is generated by a voltage difference between the pair of output terminals 28. It is to detect.

Here, considering the case where the temperature around the distortion detecting device in one embodiment of the present invention deteriorates, the temperature of one output terminal 28 of the pair of output terminals 28 in the distortion detecting device is considered. The output change rate A of the output voltage due to the change is

[0032]

(Equation 3)

## EQU2 ## Further, the output change rate B of the output voltage due to the temperature change of the other output terminal 28 of the pair of output terminals 28 in the distortion detecting device is expressed by the following equation.

[0034]

(Equation 4)

## EQU2 ##

In order to prevent the output of the distortion detecting device according to the embodiment of the present invention from fluctuating due to a change in ambient temperature, a pair of output terminals 2 in the distortion detecting device are used.
8, the output change rate A of the output voltage due to the temperature change of one output terminal 28 is determined by the output change rate B of the output voltage due to the temperature change of the other output terminal 28 of the pair of output terminals 28 in the strain detecting device. Needs to be approximately equal to Here, the output change rate A of the output voltage due to the temperature change of one output terminal 28 of the pair of output terminals 28 in the strain detection device is determined by the resistance value of one temperature characteristic adjustment resistor 26 in the pair of temperature characteristic adjustment resistors 26. Differentiating with Re,
Next formula

[0037]

(Equation 5)

## EQU2 ##

Further, the output change rate B of the output voltage due to the temperature change of the other output terminal 28 of the pair of output terminals 28 in the distortion detecting device is determined by comparing the other temperature characteristic adjustment resistor 26 with the pair of temperature characteristic adjustment resistors 26. Differentiation by the resistance value Rf gives the following equation:

[0040]

(Equation 6)

## EQU4 ## That is, according to (Equation 5) and (Equation 6), by changing the resistance values Re and Rf of one and the other temperature characteristic adjustment resistors 26 in the pair of temperature characteristic adjustment resistors 26, the output change rate A and the output change rate are obtained. B can be easily changed. As described above, in one embodiment of the present invention, on the surface of the insulating substrate 22, the first strain resistance element 25 is connected in series with the first strain resistance element 25, and the temperature coefficient of resistance thereof is set to And a temperature characteristic adjusting resistor 26 having a resistance temperature coefficient different from that of the first element portion 24, and adjusting the resistance value of the temperature characteristic adjusting resistor 26 in the first element portion 24 to form a bridge circuit. , The temperature characteristics of the two outputs are made substantially equal, so that even if there is a change in the ambient temperature, the output change rates due to the temperature change of the pair of output terminals 28 in the bridge circuit are made substantially equal to each other. It can be easily done.

Here, while changing the resistance value of the temperature characteristic adjusting resistor 26 in the first element section 24 by 50%,
Considering the case where the resistance value of the first distortion resistance element 25 is changed, the first distortion resistance element 25 and the temperature characteristic adjustment resistance 2 in the distortion detection device according to the embodiment of the present invention.
As shown in FIG. 3, the amount of change in the output of the output terminal 28 when the resistance value of the resistor 6 is changed is represented by the resistance values Rb and Rd of the first strain resistance element 25 and the resistance values Re and R
By setting it to be at least 10 times f, the rate of change of the output voltage at the output terminal 28 can be made 1% or less. Further, normally, the variation due to the variation in the temperature coefficient of resistance of each of the first strain resistance element 25 and the second strain resistance element 30 in the bridge circuit is 10% at the maximum,
In other words, since it is necessary to adjust the temperature characteristic at the output terminal 28 by at least 10%, the absolute value β of the temperature coefficient of resistance of the first strain resistance element 25, as shown in FIG.
is set to be 0.1 times or less of the absolute value of the temperature coefficient of resistance ε, δ in the temperature characteristic adjusting resistor 26. That is, the first strain resistance element 25 in the first element section 24
Of the resistance of the temperature characteristic adjusting resistor 26 to 10
And the first strain resistance element 25
By setting the absolute value of the temperature coefficient of resistance of the temperature characteristic adjusting resistor 26 to 0.1 times or less of the absolute value of the temperature coefficient of resistance of the temperature characteristic adjusting resistor 26, even if the resistance value of the temperature characteristic adjusting resistor 26 is adjusted, This makes it difficult for the combined resistance of the first element unit 24 to change even when the output change rates due to temperature changes of the pair of output terminals 28 in the bridge circuit are substantially equal to each other. Since the output does not change, the output does not fluctuate due to a change in ambient temperature, and the external force to be measured is zero, and the output voltages of the pair of output terminals 28 at the initial temperature can be made substantially equal to each other.

In the distortion detecting device according to the embodiment of the present invention, the temperature characteristic adjusting resistor 26 is connected in series to the first distortion resistance element 25, as shown in FIGS. 5 and 6. As described above, the temperature characteristic adjusting resistor 26a is connected to the first
Even when connected in parallel to the distortion resistance element 25a, the same operation and effect as in the embodiment of the present invention can be obtained.

[0044]

As described above, the strain detecting apparatus according to the present invention comprises an insulating substrate made of an elastic material, a first strain resistance element provided on the surface of the insulating substrate, and a first strain resistance element. At least two first element portions connected in series and having a temperature characteristic adjustment resistor having a temperature coefficient of resistance different from the temperature coefficient of resistance of the first strain resistance element, and provided on a surface of the insulating substrate; The second element connected in series to the first element section
And at most two second element sections composed of the above-described strain resistance elements, and the at least two first element sections and at most two second element sections constitute a bridge circuit composed of four element sections. In addition, the temperature characteristics of the two outputs in the bridge circuit are made substantially equal by adjusting the resistance value of the temperature characteristic adjusting resistor in the first element portion. According to this configuration, the insulating substrate On the surface, at least two first resistance elements each including a first distortion resistance element and a temperature characteristic adjusting resistor connected in series with the first distortion resistance element and having a temperature coefficient of resistance different from that of the first distortion resistance element. By providing one element unit and adjusting the resistance value of the temperature characteristic adjusting resistor in the first element unit, the temperature characteristics of the two outputs in the bridge circuit become substantially equal. Therefore, even if there is a change in the ambient temperature, it is easy to make the output change rates due to the temperature change of the two output terminals in the bridge circuit substantially equal to each other, and as a result, the characteristics are stable. This has an excellent effect that a distortion detecting device can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a distortion detection device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of the distortion detector.

FIG. 3 is a diagram showing a change rate of an output voltage of the distortion detection device.

FIG. 4 is a diagram showing a resistance temperature coefficient adjustment amount of the strain detection device.

FIG. 5 is a perspective view of a distortion detection device according to another embodiment of the present invention.

FIG. 6 is a circuit diagram of the distortion detector.

FIG. 7 is a perspective view of a conventional strain detection device.

FIG. 8 is a circuit diagram of the distortion detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 22 Insulating substrate 24 1st element part 25, 25a 1st distortion resistance element 26, 26a Temperature characteristic adjustment resistance 29 2nd element part 30 2nd distortion resistance element

Claims (3)

[Claims] An insulating substrate made of an elastic material; a first strain-resisting element provided on a surface of the insulating substrate and connected in series to the first strain-resisting element; At least two first element sections each including a temperature characteristic adjustment resistor different from the resistance temperature coefficient of the strain resistance element, and a second element section provided on the surface of the insulating substrate and connected in series to the first element section; And at most two second element sections composed of the above-described strain resistance elements, and the at least two first element sections and at most two second element sections constitute a bridge circuit composed of four element sections. In addition, a distortion detection device in which the temperature characteristics of two outputs in the bridge circuit are made substantially equal by adjusting a resistance value of a temperature characteristic adjustment resistor in the first element portion. 2. The resistance value of the first strain resistance element in the first element portion is set to be 10 times or more the resistance value of the temperature characteristic adjustment resistance, and the absolute temperature coefficient of the resistance of the first strain resistance element is absolute. 2. The strain detecting device according to claim 1, wherein the value is set to be equal to or less than 0.1 times an absolute value of a resistance temperature coefficient of the temperature characteristic adjusting resistor. 3. An insulating substrate made of an elastic material, provided on a surface of the insulating substrate, and connected to a first strain resistance element and the first strain resistance element in parallel with each other. At least two first element sections each including a temperature characteristic adjustment resistor different from the resistance temperature coefficient of the strain resistance element, and a second element section provided on the surface of the insulating substrate and connected in series to the first element section; And at most two second element sections composed of the above-described strain resistance elements, and the at least two first element sections and at most two second element sections constitute a bridge circuit composed of four element sections. In addition, a distortion detection device in which the temperature characteristics of two outputs in the bridge circuit are made substantially equal by adjusting a resistance value of a temperature characteristic adjustment resistor in the first element portion.