JPH02218903A - Wiring method for resistor type sensor - Google Patents

Abstract

PURPOSE:To decrease the total number of connecting lines by leading out a first connecting line from one end of each of a plurality of resistor type sensors which are arranged in close proximity, shorting the other ends, and leading out the second and third connecting lines from the shorted parts. CONSTITUTION:When the resistance change in a strain gage 1a is measured with a measuring device 5a, a second end Ta2 of the gage 1a is connected to the measuring device 5a by a three-line method. The second end Ta2 is used as one output terminal of a Wheatstone bridge 7. The resistance change of the gage 1a is converted into the output voltage through the bridge 7. The output voltage is amplified in an amplifier 10 and measured. When the resistance change in a platinum temperature measuring resistor 1b is measured with a measuring device 5b, the second end Tb2 of the resistor 1b is connected to the second end Ta2 of the gage 1a which is in turn connected to the measuring device 5b by the three-line method. The second end Tb2 is used as one output terminal of the bridge 7. The resistance change of the resistor 1b is measured by the same way. Thus, the total number of the connecting lines can be de creased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is a method for using a resistance sensor such as a strain gauge or a resistance temperature detector when measuring a resistance change according to a physical quantity of the resistance sensor using a measuring instrument. The present invention relates to a method of connecting to the measuring device.

(Prior Art) When measuring the resistance change of such a resistance type sensor, normally three resistors are provided in a measuring device a, b2, . Connect resistance type sensor C to b3 with code d,,
d, the resistive sensor C and the resistors b+, bz, and bz together form a Wheatstone bridge e, and an input signal from the power source f is connected between a pair of diagonal input terminals of the bridge e. A voltage is applied, and the output voltage corresponding to the resistance change of the resistive sensor C between the other pair of diagonal output terminals of the bridge e is amplified and measured by the amplifier g.

At this time, if the above output terminal is set in the measuring device a, if there is a temperature change in the resistance value of the connection cords d+ and dz, the resistance change of the resistance type sensor C will not be measured accurately.
In order to perform this temperature compensation, a resistance type sensor C is usually connected to a measuring device a using a three-wire method as shown in FIG.

In this three-wire method, one of the above output terminals is used as one end of the resistive sensor C, and a connection code d, separate from the connection codes d+ and dz, is derived from the one end and connected directly to the input side of the amplifier g,
In this method, one of the output signals from the pair of output terminals of the Wheatstone bridge e is directly taken out from one end of the resistive sensor C. That is, in the three-wire method, three connection cords dl+dz and dz are derived from the resistance sensor C and connected to the measuring device a.

By the way, when measuring physical quantities such as strain and temperature using resistive sensors, it is often the case that the resistance changes of multiple resistive sensors attached to the object to be measured are measured in close proximity to each other. In such cases, when connecting each resistive sensor to a measuring device using the three-wire method described above, conventionally, three connection cords were derived for each resistive sensor and connected to the measuring device as described above. was.

However, because three connection cords are derived for each resistance sensor in this way, the number of connection cords increases, making it easy to make incorrect connections to the measuring instrument, and making the connection work time-consuming. was.

Furthermore, especially when the object to be measured and the measuring device are located far apart, many long connection cords must be used, increasing measurement costs.

(Problem to be Solved) The present invention solves this inconvenience, and connects each of a plurality of resistance type sensors close to each other to a measuring instrument via a connecting wire such as a connecting cord using a three-wire method. It is an object of the present invention to provide a wiring connection method that can reduce the number of connection lines from the plurality of resistance sensors to the measuring device when measuring a change in resistance of a sensor.

(Means for Solving the Problems) In order to achieve the above object, the method for connecting a resistive sensor of the present invention includes a Wheatstone bridge configured by connecting resistive sensors, and the bridge connects the physical quantity of the resistive sensor. In a measuring instrument that converts and measures a corresponding resistance change into an output signal, a method of connecting each of a plurality of resistance sensors close to each other as the resistance sensor using a three-wire method, A first connecting wire is led out from one end, and the other ends are short-circuited at positions close to each other, and second and third connecting wires are led out from the short-circuited point, and the resistance change of each resistive sensor is sequentially measured. In this case, the first connection line and the second and third connection lines of the resistance type sensor for measuring the resistance change are connected to the measuring device using a three-wire method.

In addition, it is equipped with a Wheatstone bridge configured by connecting resistive sensors, and the bridge converts the resistance change according to the physical quantity of the resistive sensor into an output signal, and the output signal is amplified by a high input impedance amplifier. A method of connecting each of a plurality of resistive sensors close to each other as the resistive sensors using a three-wire method, in which a first connecting line is led out from one end of each resistive sensor. In addition, the other ends of the resistive sensor are short-circuited at positions close to each other, and a second connection line is led out from the short-circuited point, and the resistive sensor measures the resistance change when successively measuring the resistance change of each resistive sensor. The first connection line, the second connection line, and the first connection line of another resistance type sensor different from the resistance type sensor that measures the resistance change are at least the first connection line of the other resistance type sensor. The measuring device is characterized in that a connecting line is connected to the measuring device using a three-wire method in which the connecting line is connected to the input end of the amplifier.

(Function) According to this means, when the resistance change of each of the resistive sensors is sequentially measured by the measuring device, the other end of each resistive sensor at the short circuit point is connected to one output end of the Wheatstone bridge. and the second and third connecting wires led out from the short circuit point and the first connecting wire led out from one end of the resistive sensor that measures the resistance change are connected to the measuring device in a three-wire method. be done. At this time, the second and third connection lines are commonly used to measure the resistance change of each resistance type sensor, and the total number of connection lines is the number of resistance type sensors plus two.

Further, a first connecting wire is led out from one end of each of the resistive sensors, and the other ends are short-circuited at a position close to each other, and a second connecting wire is led out from the short-circuited point. When sequentially measuring a resistance change, the first connection line of the resistance sensor that measures the resistance change, the second connection line, and the first connection line of another resistance sensor that is different from the resistance change that measures the resistance change. When the first connecting wire of the other resistive sensor is connected to the measuring device using a three-wire method in which at least the first connecting wire of the other resistive sensor is connected to the input side of the amplifier, the resistance change of each resistive sensor is sequentially measured. During measurement, a first connection line led out from one end of a resistive sensor that measures resistance change and a second connection line led out from the short circuit point are connected to the Wheatstone bridge, and the short circuit point The other end of the resistive sensor is set as one output end of the Wheatstone bridge and connected to the input side of the amplifier via the first connecting wire of the other resistive sensor, and these connections allow each resistive sensor to A sensor is wired to the measuring device in a three-wire method. Therefore, the second connection line is commonly used for measuring the resistance change of each resistance type sensor, and the first connection line of each resistance type sensor and the first connection line of other resistance type sensors are used. The total number of connection wires is the number of resistive sensors plus one. At this time, the other end, which is the two output ends, is connected to the amplifier via the other resistive sensor, but since the amplifier has high human power impedance, the resistance of the other resistive sensor is You can safely ignore the value.

(Example) The first example of the wiring method for the resistance type sensor of the present invention is shown in Fig. 1 (
This will be explained according to a) and (b). Figure 1(a), (
b) is a connection diagram between a resistance type sensor and a measuring device.

In Figures 1(a) and (b), la and lb are strain gauges and platinum resistance temperature detectors, respectively, 2a and 2b are connection cords that are first connection wires, and 3 and 4 are second and third connections, respectively. Connection cords 5a and 5b are measuring instruments for measuring the resistance change of the strain gauge 1a and the resistance change of the platinum resistance temperature detector 1b, respectively. The strain gauge 1a and the platinum resistance temperature sensor 1b are resistance sensors whose resistance values change depending on the strain and temperature of an object to be measured (not shown) to which they are attached.

The connection cords 2a and 2b are led out from the first ends Ta, Tb of the strain gauge la and the platinum resistance temperature detector 1b, respectively, and are led out from the second end Ta of the strain gauge 1a and the platinum resistance temperature detector 1b.
z and 'rb2 are short-circuited by a short connecting cord 6 at positions close to each other. The connection cord 3.4 is led out from the second end Ta of the strain gauge 1a.

Measuring devices 5a and 5b have the same configuration as the measuring device a shown in FIG. , 8c, a power supply 9 for applying an input voltage to the bridge 7, and an amplifier 10 for amplifying the output voltage of the bridge 7, similarly to the measuring instrument a. However, the resistance values of the resistors 8a, 8b, 8c of the measuring instrument 5a are the same as those of the strain gauge 1a, and the resistance values of the resistors 8a, 8b+80 of the measuring instrument 5b are the same as that of the platinum resistance temperature detector 1b. has been done.

When measuring the resistance change of the strain gauge 1a with such a measuring device 5a, the second end Ta of the strain gauge 1a is used as one output end of the Wheatstone bridge 7 and three wires are connected as shown in FIG. The measuring device 5a is connected according to the method. That is,
A connection cord 2a led out from the first end Ta of the strain gauge 1a and a connection cord 3 led out from the second end Ta are connected to the resistors 8a and 8c of the measuring device 5a to form a Wheatstone bridge 7. Furthermore, together with the connection cord 3, a connection cord 4 led out from the second end Taz is connected to the input side of the amplifier 10. Through these connections, the change in resistance of the strain gauge 1a is converted into an output signal by the Wheatstone bridge 7, and the output signal is amplified by the amplifier 10 and measured.

On the other hand, when measuring the resistance change of the platinum resistance temperature detector 1b using the measuring device 5b, the strain gauge 1 is used as shown in FIG. 1(b).
The second end Tb of the platinum resistance thermometer 1b, which is short-circuited to the second end Ta of the terminal a through the connecting cord 6, is connected to the measuring instrument 5b using the three-wire method as one output end of the Wheatstone bridge 7. . That is, the first end Tb of the platinum resistance temperature sensor 1b,
The connection cord 2b derived from the above and the connection cord 3 are connected to the resistors 8a and 8c of the measuring instrument 5b to form a Wheatstone bridge 7, and the connection cord 4 is connected to the input side of the amplifier 10. Ru. By connecting these wires, the change in resistance of the platinum resistance temperature detector 1b is measured in the same manner as described above.

Therefore, in any of the above measurements, the strain gauge 1a
And the short-circuited point by the connection cord 6 of the platinum resistance temperature detector 1b becomes one output end of the Wheatstone bridge 7, and the connection cords 3 and 4 are used in common, and the strain gauge 1a and the platinum resistance temperature detector 1b are connected to the measuring instrument. The total number of connection cords for connecting to 5a and 5b using the three-wire method is four.

Further, by using this wiring method, it is also possible to automatically measure the resistance change of the strain gauge 1a and the platinum resistance temperature detector 1b using the measuring device 5c shown in the second figure.

This measuring device 5c has the respective Wheatstone bridges 7.7 in the measuring devices 5a, 5b connected to a power source 9 and an amplifier 10 via switch groups Sa, Sb which are automatically turned on and off in sequence. As shown in the figure, the connection cords 2a, 2b.

3.4 is connected to the measuring device 5C. At this time, when the switch groups Sa and Sb are sequentially turned on, the Wheatstone bridges 7.7 are sequentially activated in response to this, resulting in the connections shown isometrically in FIGS. 1(a) and 1(b), respectively. Similarly to the above, the resistance change of the strain gauge 1a and the platinum resistance temperature sensor 1b is measured by the three-wire method.

In the first example above, the strain gauge 1a is used as a resistance sensor.
and a platinum resistance temperature sensor 1b, but even if a large number of resistance sensors such as strain gauges and resistance temperature sensors are used, it is possible to In the same way as above, connect each resistive sensor to a measuring instrument using the 3-wire method by deriving the connecting cord, shorting the other ends at positions close to each other, and deriving the two connecting cords from the shorted point. It goes without saying that the total number of connection cords is the number of resistive sensors plus two.

Next, a second example of the method of connecting a resistive sensor according to the present invention will be explained with reference to FIGS. 3(a) and 3(t)). Figure 3 (a
).

(b) is a wiring diagram of the strain gauge 1a, the platinum resistance temperature detector 1b, and the measuring instruments 5a and 5b.

In this connection method, the strain gauge 1a and the platinum resistance temperature sensor 1b are short-circuited by the connection cord 6 in the same manner as described above, and the first end Ta of the strain gauge 1a is short-circuited by the connection cord 6.

Connection cords 2a and 2b are led out from the first end Tb of the platinum resistance temperature detector 1b, respectively, and
Only the connection cord 3 is led out from the second end Taz of the strain gauge 1a, which is short-circuited to. When measuring the resistance change of the strain gauge 1a and the platinum resistance temperature detector 1b, the wires are connected to the measuring devices 5a and 5b, respectively, as follows.

When measuring the resistance change of the strain gauge 1a with the measuring device 5a, as shown in FIG.
A connection cord is connected to constitute the Wheatstone bridge 7, and the second end Tat of the strain gauge 1a is used as one output end of the Wheatstone bridge 7, and the connection cord is led out from the second end Taz via the platinum resistance temperature detector 1b. 2b is connected to the input side of the amplifier 10, and these connections connect the strain gauge la to the measuring device 5a using the three-wire method. In the measurement at this time, the output signal from the second end Taz of the strain gauge 1a is sent to the amplifier 10 via the platinum resistance thermometer 1b.
However, the input impedance of the amplifier 10 is set to be a sufficiently higher impedance than the resistance value of the strain gauge 1a and the platinum resistance temperature detector 1b, and the resistance value of the platinum resistance temperature detector 1b is the same as that of the Wheatstone bridge 7. has almost no effect on the output voltage.

On the other hand, when measuring the resistance change of the platinum resistance temperature detector 1b with the measuring instrument 5b, as shown in FIG. 3(b), the connecting cord 2b and the connecting cord 3 are 8
c to form the Wheatstone bridge 7, and the second end Tbz of the platinum resistance thermometer 1b is short-circuited to the second end Ta2 of the strain gauge 1a via the connection cord 6.
As one output end of the Wheatstone bridge 7, the connection cord 2a led out from the second end Tb2 via the connection cord 6 and the strain gauge 1a is connected to the input side of the amplifier 10, and these connections connect the platinum temperature measuring resistor to the input side of the amplifier 10. The body 1b is connected to the measuring device 5b using a three-wire method. And at this time, amplifier 1
0 is considered to be a high input impedance, and the resistance change of the platinum resistance temperature detector 1b can be measured without any problem.

Therefore, in any of the above measurements, the connection cord 3
are commonly used, and when either one of the connection cord 2a including the strain gauge 1a and the connection cord 2b including the platinum resistance temperature detector 1b is used in connection to the amplifier 10, the strain gauge 1a is connected to the amplifier 10. and platinum resistance temperature detector 1b was measured R15a.

The total number of connection cords to connect to 5b using the 3-wire method is 3.
It becomes a book.

Also, like the measuring device 5C, there is a switch group Sa.

By connecting the connection cords 2a, 2b, and 3 as shown in the fourth figure to the measuring instrument 5C for automatic measurement shown in the fourth figure, which is equipped with a It is possible to automatically measure the resistance change of the gauge 1a and the platinum resistance temperature detector 1b.

In addition, in the second example, the strain gauge 1a is used as a resistance type sensor.
and platinum resistance temperature sensor 1b, but even if a large number of resistance sensors such as small gauges and resistance temperature sensors are used, the same steps can be taken from one end of each resistance sensor as above. Connect each resistive sensor to the measuring instrument using the three-wire method in the same manner as above by deriving the connection cord, shorting the other ends at a position close to each other, and deriving the connection cord from the shorted point. Of course, the total number of connection cords is the number of resistive sensors plus one.

(Effects) As is clear from the above description, according to the resistive sensor wiring method of the present invention, the first connection line is led out from one end of each of a plurality of resistive sensors that are close to each other, and
By shorting the other ends and leading the second and third connecting wires from the shorted point, the second and third connecting wires can be used in common when measuring the resistance change of each resistive sensor in sequence. Each resistive sensor can be sequentially connected to the measuring device using the 3-wire method, reducing the total number of connection wires and preventing incorrect wiring of each resistive sensor to the measuring device. .

In addition, when the first connecting wire is led out from one end of each of a plurality of resistive sensors, and the other ends are short-circuited and only the second connecting wire is led out from the shorted point, the resistance change of each resistive sensor is When performing sequential measurements, the second connection line is used in common, and the first connection line derived from another resistance type sensor different from the resistance type sensor that measures the resistance change is connected to the high input impedance of the measuring instrument. By connecting to the input side of the amplifier, each resistive sensor can be successively connected to the measuring instrument in a three-wire method, further reducing the total number of connecting wires.

[Brief explanation of the drawing]

FIGS. 1(a), (b) and 2 are wiring diagrams for explaining a first example of the wiring method for a resistive sensor of the present invention, and FIGS. 3(a), (b) and 4. The figure is a wiring diagram for explaining the second example, and FIG. 5 is a wiring diagram for explaining the conventional wiring method. la, lb...Resistive sensor 2a, 2b...First connection line 3...Second connection line 4...Third connection line 5a,
5b, 5c, 5c' - Measuring device 7 Wheatstone bridge 10 Amplifier FIG, 1 (0) FIG, 1 (b) FI G, 3 (a) FIG, 3 (b) h

Claims (1)

[Claims] 1. A measuring instrument that includes a Wheatstone bridge configured by connecting a resistive sensor, and that measures a change in resistance according to a physical quantity of the resistive sensor by converting it into an output signal by the bridge, A method of connecting each of a plurality of resistive sensors close to each other as the resistive sensor using a three-wire method, in which a first connecting line is led out from one end of each resistive sensor, and the other ends are connected to each other. is short-circuited at a position close to the short circuit, and second and third connecting wires are led out from the short-circuited point, and when the resistance change of each resistance type sensor is sequentially measured, the first connection line of the resistance type sensor that measures the resistance change is A method for connecting a resistive sensor, characterized in that a connecting line and the second and third connecting lines are connected to the measuring device using a three-wire method. 2. Equipped with a Wheatstone bridge configured by connecting resistive sensors, the bridge converts the resistance change according to the physical quantity of the resistive sensor into an output signal, and the output signal is amplified by a high input impedance amplifier. A method of connecting each of a plurality of resistive sensors close to each other as the resistive sensors using a three-wire method, in which a first connecting line is led out from one end of each resistive sensor. In addition, the other ends of the resistive sensor are short-circuited at positions close to each other, and a second connection line is led out from the short-circuited point, and the resistive sensor measures the resistance change when successively measuring the resistance change of each resistive sensor. the first connection line, and the second connection line.
The connection line and the first connection line of another resistance type sensor different from the resistance type sensor that measures the resistance change, at least the first connection line of the other resistance type sensor is connected to the input side of the amplifier. A method for connecting a resistive sensor, characterized in that the resistive sensor is connected to the measuring device using a three-wire method.