JPH11211587A - Strain gauge type converter and measurement module therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strain gauge type converter, which can eliminate measuring accuracy detectioration resulting from the length of a connecting cable, and, in addition, can make a preparatory work and measured data processing easy at the time of measuring physical quantities, and a measurement module for the converter. SOLUTION: The strain gauge type converter is constituted so that a strain starting body carrying a strain gauge 3 stuck to it, and a Wheatstone bridge circuit 4 which is constituted of the strain gauge 3 and outputs the strain measuring signal corresponding to the strained amount of the strain starting body, are packaged in an integrally formed case. In the case, a constant-voltage circuit 20 which supplies a constant voltage to the Whetstone bridge circuit 4, an A/D converter 22 which converts the strain measuring signal into digital data, and a data transmitting and processing means 30 which transmits the digital data to an external measured data processor as the measured result data as they are or after performing prescribed processing on the data, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting physical quantities such as load, displacement, and pressure into mechanical strain of a flexure element, and converting the mechanical strain into an electric signal by a strain gauge attached to the flexure element. The present invention relates to a strain gauge transducer to be extracted.

[0002]

2. Description of the Related Art Strain gauge type transducers are designed for load, displacement,
A physical element such as pressure, acceleration, or torque is extracted as an electric signal, and a strain-generating body to which a strain gauge is attached,
A Wheatstone bridge circuit formed by a strain gauge is disposed in an integrated housing, and operation power is supplied to the Wheatstone bridge circuit from the outside, and the output voltage of the Wheatstone bridge circuit is output to the outside.

When a physical quantity is applied to the strain body of the strain gauge type transducer, a stress corresponding to the physical quantity is generated inside the strain body, and a mechanical strain proportional to the stress is generated in the strain body. Then, since the resistance value of the strain gauge attached to the strain body changes according to the amount of strain generated in the strain body, the level of the output voltage (hereinafter referred to as a strain measurement signal) from the Wheatstone bridge circuit is reduced. fluctuate. That is, the level of the strain measurement signal changes according to the magnitude of the physical quantity applied to the strain body.

When a physical quantity is measured by a strain gauge type transducer, the strain gauge type transducer is connected to a measurement data processing device such as a data logger via a connection cable, so that the measurement data Operating power is supplied to the gauge transducer, and a strain measurement signal output from the strain gauge transducer is input to the measurement data processing device. The measurement data processor measures the magnitude of the physical quantity applied to the strain gauge transducer by calculating and processing the strain measurement signal obtained in this way and converting the level of the strain measurement signal into the magnitude of the physical quantity. I do.

[0005] However, since the level of the strain measurement signal is very small, when the strain gauge type transducer and the measurement data processing device are installed at a relatively distant place to measure a physical quantity, the connection cable becomes long. On the other hand, during transmission from the strain gauge type transducer to the measurement data processing device, the level of the strain measurement signal is attenuated or easily affected by external noise, so that there is a disadvantage that a measurement error is likely to occur.

In particular, in multi-point measurement of a structure or the like, the number of measurement points may be hundreds, or even thousands, and in such a case, the level of the above-described strain measurement signal is reduced to the magnitude of a physical quantity. In order to perform the conversion processing and the correction of the distortion measurement signal, the measurement data processing apparatus must perform the calculation processing for the distortion measurement signal for each measurement point.
The burden on the measurement data processing device was heavy.

In some cases, correction according to the temperature characteristics of the strain gauge or the strain element at each measurement point or correction of the non-linearity of the strain measurement signal may be required. The data processor must correct the distortion measurement signal for each measurement point, which imposes a heavy burden on the measurement data processor.

When measuring stress at a number of measurement points, the strain gauge transducers installed at each measurement point are selected by using a measurement data processing device or a strain measurement signal from each strain gauge transducer. Wiring work for connecting to a switch box that outputs to a measurement data processing device requires a great deal of labor.

Further, in a case where the strain measurement signals from the plurality of strain gauge type transducer data processing devices are selected in a time division manner via the switch box and input to one measurement data processing device, In particular, when the number of measurement points is large, a relatively large time difference occurs between the measurement times of the respective measurement points, so that it was not possible to measure the physical quantities at many measurement points at the same time in a strict sense.

[0010]

SUMMARY OF THE INVENTION In view of the above background, the present invention prevents a decrease in measurement accuracy due to the length of a connection cable, and facilitates preparation work and measurement data processing for measuring physical quantities. It is an object of the present invention to provide a strain gage applied transducer and a measurement module for the strain gage applied transducer.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a strain-generating body having a strain gauge attached thereto, and a strain gauge constituted by the strain gauge and corresponding to a strain amount of the strain-generating body. The present invention relates to an improvement of a strain gage applied transducer (hereinafter, referred to as a conventional strain gage applied transducer) in which a Wheatstone bridge circuit for outputting a measurement signal to the outside is disposed in an integrated housing.

Further, the present invention relates to a measuring module for a strain gauge type transducer which achieves the above object by connecting to a conventional strain gauge type transducer.

A conventional strain gauge type transducer is used by being connected to a measurement data processing device such as a data logger via a connection cable, and is operated from the measurement data processing device to the Wheatstone bridge circuit via the connection cable. While the power is supplied, the strain measurement signal output from the Wheatstone bridge circuit is input to the measurement data processing device via the connection cable.

Therefore, the conventional strain gauge type transducer and the measurement data processing device are installed at a relatively remote place,
If the connection cable connecting the two is long, there is a disadvantage that the distortion signal, which is a minute signal, is attenuated or easily affected by external noise.

Therefore, in order to prevent such inconvenience from occurring, the strain gauge type transducer of the present invention includes an A / D for converting the strain measurement signal into digital data in a housing of the conventional strain gauge type transducer. A converter is provided, and data communication processing means for transmitting the digital data as it is or performing predetermined processing as measurement result data to an external measurement data processing device is provided.

Further, the measuring module for a strain gauge type transducer of the present invention can be connected close to the conventional strain gauge type transducer, and the strain measurement output from the conventional strain gauge type transducer is provided. An A / D converter for converting a signal into digital data, and data communication processing means for transmitting the digital data as it is or performing predetermined processing as measurement result data to an external measurement data processing device, in an integrated housing. It is characterized by having been provided.

According to the strain gauge type converter of the present invention, since the Wheatstone bridge circuit and the A / D converter are provided close to each other, the strain measurement signal output from the Wheatstone bridge circuit is attenuated. And can be converted to digital data while avoiding the influence of noise.

Further, by connecting the measuring module for a strain gauge type transducer of the present invention in close proximity to the conventional strain gauge type transducer, the Wheatstone bridge provided in the conventional strain gauge type transducer is provided. Circuit and
The A / D converter provided in the measurement module for the strain gauge type converter is connected by a short connection line, and the strain measurement signal output from the Wheatstone bridge circuit is digitalized while avoiding the effects of attenuation and noise. Can be converted to data.

Then, the digital data of the distortion measurement signal converted by the A / D converter is transmitted to the data communication processing means by the data communication processing means. Therefore, compared to the case where the minute measurement result data is transmitted to the data communication processing means as it is, even when the connection distance with the measurement data processing device is long, the influence of external noise can be reduced. it can.

Further, when processing such as conversion of digital data of the strain measurement signal into physical quantity and correction of the digital data of the strain measurement signal is required, the data communication processing means performs these processes, and By transmitting the subsequent digital data as the measurement result data to the measurement data processing device, there is no need for the measurement data processing device to perform an operation on the measurement result data. Therefore, the load on the measurement data processing device can be reduced.

Next, when a physical quantity is measured using a strain gauge transducer, the temperature characteristics of the strain gauge, the temperature characteristics of the strain body,
Alternatively, it may be necessary to perform temperature correction in consideration of the thermal strain of the strain body.

Therefore, in order to perform such a temperature correction,
The strain gauge type converter of the present invention includes a temperature sensor for detecting a temperature of the strain body, and the A / D converter has a function of converting a temperature detected by the temperature sensor into digital data. The data communication processing means has a function of transmitting digital data of a temperature detected by the temperature sensor generated by the A / D converter to the measurement data processing device as temperature detection data.

According to the present invention, the temperature detection data of the strain body required for the temperature correction can be transmitted to the measurement data processing means together with the measurement result data.

Further, the strain gauge type transducer of the present invention
A temperature sensor for detecting a temperature of the flexure element;
The / D converter has a function of converting a temperature detection signal output from the temperature sensor into digital data, and the data communication processing means performs the temperature processing by the A / D converter in the predetermined process. The digital data of the distortion measurement signal is corrected based on the digital data of the detection signal.

According to the present invention, it is not necessary to perform the temperature correction processing on the measurement data processing device side, and processing of the measurement result data by the measurement data processing device becomes easy.

Further, the data communication processing means provided in the strain gauge type transducer of the present invention and the measuring module for the strain gauge type transducer of the present invention, in the predetermined processing, the data processing means according to the strain amount of the strain generating element. The correction of the nonlinearity of the output level of the distortion measurement signal is performed.

According to the present invention, it is not necessary to correct the non-linearity on the measurement data processing device side, and the measurement data processing by the measurement data processing device becomes easy.

Next, when measuring physical quantities at a number of locations using a conventional strain gauge transducer, a strain gauge transducer is installed at each measurement point, and each strain gauge transducer is connected to the measured data processing. The device must be connected one-to-one with a connection cable, and wiring work requires a great deal of labor.

Therefore, in order to facilitate such a wiring work, the data communication processing means provided in the strain gauge type transducer of the present invention is unique to the strain gauge provided with the data communication processing means. Has a function of receiving output instruction data corresponding to the identification code transmitted from the measurement data processing device, and having the function of receiving the measurement result data in response to the reception of the output instruction data. Is transmitted to the measurement data processing device.

Further, the data communication processing means provided in the measuring module for a strain gauge type transducer of the present invention comprises:
Having an identification code uniquely set according to the measurement module for the strain gauge transducer provided with the data communication processing means, transmitted from the measurement data processing device,
It has a function of receiving output instruction data corresponding to the identification code, and transmits the measurement result data to the measurement data processing device in response to receiving the output instruction data.

According to the present invention, one measurement data processing device and a plurality of strain gauge transducers of the present invention or measurement modules for the strain cage transducer of the present invention are connected via one common cable. And the measurement data processing device can receive the measurement result data from each data communication processing unit in a time-division manner.

That is, the measurement data processing device is uniquely provided for a plurality of strain gage-type converters of the present invention or measurement modules for the strain gage-type converter of the present invention connected to the measurement data processing device. When the output instruction data according to the set identification code is sequentially transmitted, the output instruction data is received, and the strain gauge transducer of the present invention having the identification code or the measurement module for the strain gauge transducer of the present invention having the identification code Transmitting the measurement result data to the measurement data processing device according to the output instruction data.
Therefore, it is not necessary to wire the measurement data processing device and each of the plurality of strain gage applied transducers of the present invention or the measurement modules for the strain gage applied transducer of the present invention in a one-to-one manner, thereby facilitating the wiring process.

Next, as described above, one measurement data processing device and a plurality of strain gauge transducers of the present invention or modules for the strain gauge transducer of the present invention are connected via one system common cable. When connecting and collecting measurement data of physical quantities at each measurement point in a time-sharing manner, it is not possible to measure the physical quantities at each measurement point at the same time in a strict sense.

Therefore, the data communication processing means provided in the strain gauge type transducer of the present invention and the measurement module for the strain gauge type transducer of the present invention comprises storage means for holding the measurement result data, A function of receiving the measurement start instruction data transmitted from the processing device, wherein the A / D
The measurement result data based on the output of the converter is stored in the storage unit, and the stored measurement result data is transmitted to the measurement data processing device in response to receiving the output instruction data.

According to the present invention, a plurality of strain gauge transducers of the present invention or a plurality of measurement modules for the strain gauge transducer of the present invention are provided for one measurement data processing means in the same manner as described above. When the measurement start data is output from the measurement data processing means to the common signal path when connected via one common signal path, each of the strain gauge transducers of the present invention or the strain gauge of the present invention The data communication processing means provided in the measurement module for the expression converter receives the measurement start data at the same time, and holds the measurement result data at the time of the reception in the storage means.

Then, the measurement data processing device sequentially transmits the output instruction data corresponding to the identification code to each of the plurality of strain gauge transducers of the present invention or the measurement module for the strain gauge transducer of the present invention. By doing so, from the respective data communication processing means provided in the strain gauge transducer of the present invention or the measurement module for the strain gauge transducer of the present invention, it was measured at the time of receiving the measurement start data, and held in the storage means. The measurement result data can be received in a time-division manner.

Thus, the measurement data processing device can
The measurement result data at the same time can be acquired in a time-division manner from each of the strain gage applied transducers and the measurement module for the strain gage applied transducer of the present invention.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram in a case where pressure is measured at a large number of measurement points using the strain gauge transducer of the present invention. FIG. 2 is a circuit configuration diagram of the strain gauge transducer shown in FIG.

Referring to FIG. 1, a strain gauge type transducer 1 of the present invention includes four strain gauges 3 adhered to a flexure element 2 and a Wheatstone bridge circuit 4 constituted by the strain gauges 3. The measurement unit 5 is connected to the measurement data processing device 10 via a common cable 8 and a connector 9 connected to the connector 7.

The pressure P is applied to the strain gauge type transducer 1 from outside.
Is applied, a stress σ corresponding to the pressure P is generated inside the strain element 2.
Occurs. Then, a strain proportional to the stress σ is generated in the flexure element 2, and the resistance value of the strain gauge 3 attached to the flexure element 2 changes.

Referring to FIG. 2, a constant voltage V is applied from a measuring unit 5 to a Wheatstone bridge circuit 4 composed of a strain gauge 3, so that the output Δe from the Wheatstone bridge circuit 4 is a resistance of the strain gauge. It fluctuates as the value changes. Thereby, the magnitude of the pressure P applied to the strain gauge type transducer 1 becomes Δe (hereinafter, referred to as “Δe”).
The signal is converted to a level of an electric signal called a strain measurement signal) and output to the measurement unit 5.

Referring to FIG. 2, measuring unit 5 is a miniaturized required circuit using a one-chip microcomputer or the like, and is connected to Wheatstone bridge circuit 4 and its vicinity.

The measuring unit 5 includes a constant voltage circuit 20 for supplying a constant voltage V to the Wheatstone bridge circuit 4, an amplifier 21 for receiving and amplifying the distortion measurement signal Δe output from the Wheatstone bridge circuit 4, and an amplifier 21.
A / D converter 22 for converting the output of the digital camera into digital data
A control circuit (CPU) 23 that performs predetermined processing such as overall operation control of the measurement unit 5 and various correction processing for digital data of the distortion measurement signal Δe input from the A / D converter 22; A storage circuit 24 for storing the operation program and various data, an interface circuit 25 for transmitting and receiving data to and from the measurement data processing device 10 shown in FIG.
The main power supply circuit 26 generates a predetermined voltage to be supplied to a circuit unit such as the control circuit 23 from the operating power supplied from 0.

The control circuit 23 constitutes the data communication processing means 30 of the present invention together with the storage circuit 24 and the interface circuit 25.

The storage circuit 24 includes a ROM in which an operation program of the control circuit 23 is stored in advance, a RAM in which measurement result data generated by the control circuit 23 is stored, and an A / D converter. EEPRO for storing and holding parameter data and the like used for predetermined processing on digital data of the strain measurement signal input from the converter 23
M. Further, an identification code (ID) unique to each strain gauge type transducer 1 is stored in advance in the EEPROM.
Code) is stored.

The measurement data processing device 10 shown in FIG. 1 is configured using a microcomputer, and supplies the operating power to the measurement unit 5 of each strain gage applied transducer 1 via a common cable 8. At the same time, various instruction data are transmitted. Further, measurement result data and the like transmitted from each strain gauge type transducer 1 are received via the common cable 8, and the received data is processed, stored and displayed (display on a display (not shown) or printing display by a printer). Etc.).

Next, referring to FIG. 1 and FIG. 2, each strain gage applied transducer 1 in a case where a plurality of strain gage applied transducers 1 are used to measure the pressure applied to a plurality of measurement points. The operation of will be described.

Referring to FIG. 1, when simultaneously measuring the pressure applied to a plurality of points of an object such as a building or a machine, the strain gauge type transducers 1 are installed at the pressure measuring points, respectively, and each strain gauge type conversion is performed. The device 1 is connected to the measurement data processing device 10 via a common cable 8 of one system.

By connecting in this way, a power supply for operation is supplied to each strain gauge transducer 1 from the measurement data processing device 10 via the common cable 8. Referring to FIG. 2, when power for operation is supplied to measuring section 5 from connector 7 connected to common cable 8, predetermined voltage generated by main power supply circuit 26 is applied to circuit sections such as control circuit 23. Then, the control circuit 23 and the like start operating.

When "measurement start instruction data" for instructing the start of pressure measurement is transmitted from the measurement data processing device 10, each of the strain gauge transducers 1
And simultaneously receives the "measurement start instruction data" via the.
When receiving the “measurement start data”, the control circuit 23 starts applying a voltage from the constant voltage circuit 20 to the Wheatstone bridge circuit 4.

Here, the constant voltage circuit 20 generates a constant voltage from the operating power supply supplied from the measurement data processing device 10, and the Wheatstone bridge circuit 4 operates even if the operating power supply voltage fluctuates. The voltage applied to is kept constant.

As described above, the Wheatstone bridge circuit 4
, A strain measurement signal Δe corresponding to the pressure P applied to the strain element 2 is output from the Wheatstone bridge circuit 4, and the strain measurement signal Δe is amplified by the amplifier 21 and A / D The data is converted into digital data by the converter 22.

Then, the control circuit 23 of the strain gauge type converter fetches the digital data of the strain measurement signal output from the A / D converter and stores it in the RAM of the storage circuit 24. Since the above-described processing is simultaneously executed in each strain gage applied transducer 1, the measurement result data at the same time (“measurement start instruction data” reception time) is held in the storage circuit 24 of each strain gage applied transducer 1. Is done.

Next, the measurement data processing device 10 selects the identification codes (ID codes) uniquely set for the respective strain gage applied transducers 1 (for example, in order) and selects the identification codes. "Output instruction data" including the identified identification code is transmitted. This “output instruction data” is simultaneously received by each strain gauge type transducer 1 via the common cable 8.

Control circuit 23 of each strain gauge transducer 1
Captures the “output instruction data” via the interface circuit 25, extracts the identification code included in the “output instruction data”, and stores the extracted identification code in the storage circuit 2.
4 to determine whether or not it matches its own identification code held in the EEPROM.

When the identification code extracted from the "output instruction data" matches the identification code of its own, the control circuit 23 of each strain gage applied transducer 1 determines that
The measurement result data held in the RAM No. 4 is transmitted via the interface circuit 25, and when they do not match, the measurement result data is not transmitted.

Thus, every time the “output instruction data” is transmitted from the measurement data processing device 10, one of the strain gauge transducers having the identification code included in the “output instruction data” The measurement result data is sequentially transmitted, and the measurement result data transmitted from each strain gauge transducer 1 does not conflict on the common cable 8.

Therefore, the measurement data processing device 10
The measurement result data at the same time (“measurement start instruction data” reception time) can be received in a time-division manner via a single common cable 8.

Then, the measurement data processing device 10 displays the measurement result data received and collected at each measurement point as it is, or converts the measurement result data into a magnitude of pressure on a display (not shown), or a recording device. To finish the pressure measurement at a number of measurement points.

According to the strain gauge type transducer 1 of this embodiment, the Wheatstone bridge circuit 4 constituted by the strain gauge 3 is connected to the measuring unit 5 in the vicinity thereof. Therefore, the connection lines 31, 32, 3
3 and 34 need only be extremely short. Therefore, the voltage applied from the constant voltage circuit 20 drops due to the resistance of the connection lines 31 and 32, and the strain measurement signal Δe output from the Wheatstone bridge circuit 4 is connected to the connection line 33. , 34 before being input to the amplifier 21, there is almost no influence of external noise.

Since the communication between the strain gauge transducer 1 and the measurement data processing device 10 is performed by digital data, even if the length of the common cable 8 becomes longer, the resistance of the common cable 8 increases, and the disturbance is increased. Less susceptible to noise.

Therefore, it is possible to prevent the connection line from adversely affecting the measurement accuracy and the measurement stability, to accurately measure the pressure P at each measurement point, and to stably perform the measurement. .

Further, since each strain gauge type transducer 1 and the measurement data processing device 10 need only be connected via one common cable 8, these wiring processes can be easily performed.

Further, in the control circuit 23, the digital data of the strain measurement signal Δe input from the A / D converter 22 is converted into the distortion amount ε of the strain element 2 by the following equations (1) and (2). The converted digital data may be converted into the stress σ generated in the strain body corresponding to the strain amount ε, and the converted digital data may be transmitted to the measurement data processing device 10 as the measurement result data. Processing of the measurement data on the measurement data processing device side is facilitated.

Ε = (4Δe) / (KV) (1) σ = Eε (2) where K is the gauge factor of the strain gauge 3 and E is the Young of the strain element 2. These data are the EE of the storage circuit 24.
It is stored in the PROM in advance.

Next, a second embodiment of the present invention will be described.
This will be described with reference to FIGS. The strain gauge transducer of the second embodiment is different from the strain gauge transducer 1 shown in FIG. 1 only in that a temperature sensor for detecting the temperature of the strain generating element 2 is provided. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

FIG. 3 is an overall configuration diagram in the case where a multipoint stress is measured using the strain gauge type transducer of the present invention in the second embodiment. FIG. 4 is a circuit configuration diagram of the strain gauge transducer shown in FIG.

Referring to FIG. 3, strain gauge type transducer 5
0, a temperature sensor 5 for detecting the temperature of the flexure element 2
1 (for example, a thermocouple) is provided, and the temperature sensor 51 is connected to the measurement unit 5.

In this case, referring to FIG. 4, the measuring unit 5 has the circuit configuration shown in FIG.
0, an amplifier 21, an A / D converter 22, a control circuit 23, a storage circuit 24, an interface circuit 25, and a main power supply circuit 26, and a switch 52. A signal obtained by amplifying the strain measurement signal Δe output from the Wheatstone bridge circuit 4 by the amplifier 21 and a detection signal (hereinafter, referred to as a temperature detection signal) of the temperature sensor 51 are input to the switching circuit 52, and these are controlled. Under the control of the circuit 23, the data is selectively switched and output to the A / D converter 22, where it is converted into digital data.

Next, referring to FIG. 3, the operation of the strain gage applied transducer 50 when a plurality of strain gage applied transducers 50 are used to measure the pressure P applied to a plurality of measurement points will be described. .

When the “measurement start instruction data” described in the first embodiment is transmitted from the measurement data processing device 10 to the strain gauge type converter 50 in FIG. 3, each strain gauge type converter 50 The following processing is performed.

That is, referring to FIG. 4, when control circuit 23 of measurement unit 5 receives “measurement start instruction data” through interface circuit 25, switch 52 switches to the side of Wheatstone bridge circuit 4 and temperature sensor 51. Side, and the A / D converter 22 sequentially converts the strain measurement signal Δe and the temperature detection signal into digital data, and fetches the digital data.

Then, the control circuit 23 obtains the strain amount ε of the flexure element 2 from the above equation (1). Here, for example, under measurement environment conditions in which the temperature of the flexure element 2 greatly changes, the strain amount ε obtained from the data of the strain measurement signal Δe includes not only the pressure P acting on the flexure element 2 but also A component due to thermal strain of the strain body 2 or the strain gauge 3 itself is included. The measurement sensitivity also changes due to the temperature characteristics of the strain gauge 3 and the like.

Therefore, in the second embodiment, the control circuit 23 of each strain gauge transducer 50
By performing the correction operation of the following expression (3) using the temperature t indicated by the digital data of the temperature detection signal of No. 1, the pressure P
To determine the true strain amount εx.

Εx = (ε−apparent strain at temperature t) · k (t) (3) Here, the apparent strain in (3) is the true strain due to the pressure P in the strain element 2. This is the amount of strain that can be grasped from a strain measurement signal Δe that appears due to factors other than the pressure P, such as the thermal strain of the strain body 2 and the thermal strain of the strain gauge 1 itself, in a state where it does not occur. The value at the temperature t is calculated based on the temperature detection signal of the temperature sensor 51 by using, for example, a data table or an arithmetic expression previously stored in the EEPROM of the storage circuit 24 for each strain gauge type transducer 50. Ask from. Further, k (t) in equation (3) is a coefficient (a function of temperature t) for correcting the measurement sensitivity, and the value of this correction coefficient k (t) is also stored for each strain gauge type transducer 50. The temperature is obtained from the temperature t based on the temperature detection signal of the temperature sensor 51 using a data table, an arithmetic expression, or the like previously stored in the EEPROM of the circuit 24.

The contents stored in the EEPROM are as follows:
It may be rewritten at any time according to the purpose or necessity.

Then, the control circuit 23 of each strain gauge type transducer 50 determines the true strain amount ε obtained as described above.
x (digital data) is stored and held in the RAM of the storage circuit 24 as measurement result data, and the stored measurement result data is transmitted from the measurement data processing device 10 to each strain gauge as in the first embodiment. Equation converter 50
When the “output instruction data” including the identification code for each is given, it is transmitted to the measurement data processing device 10 via the common cable 8.

As a result, on the measurement data processing device 10 side, data indicating the true strain amount εx of the flexure element 2 at each measurement point is obtained.

According to the strain gage applied transducer 50 of the second embodiment, the same operation and effect as those of the strain gage applied transducer 1 of the first embodiment can be obtained. In the gauge type converter 50, the correction processing according to the temperature t of the strain body 2 is performed, so that the measurement data processing apparatus 10 does not need to perform the correction according to the temperature for each measurement point, and the post-processing is performed. It becomes very easy. Moreover, since the correction processing according to the temperature of the strain generating element 2 for each measurement is performed independently and in parallel in each of the strain gauge transducers 50, the correction processing can be performed efficiently.

In the second embodiment, each strain gauge type transducer 50 performs a correction process in accordance with the temperature t of the strain element 2.
From 0, the digital data of the temperature detection signal is transmitted to the measurement data processing device 10 together with the digital data of the strain measurement signal Δe or the data of the strain amount ε based thereon, and the measurement data processing device 10 performs the above-described temperature correction. Processing may be performed.

Even in such a case, since the data transmitted from each of the strain gauge type transducers 50 to the measurement data processing device 10 is digital data, the influence of the resistance of the common cable 8, the external noise, and the like. , And accurate measurement can be stably performed.

Further, the magnitude of the pressure P applied to the strain generating element 2 and the strain ε of the strain generating element 2 when the pressure P is applied are not completely proportional to each other. May have a non-linearity of about several percent. Therefore, when the measurement accuracy is particularly problematic, in the first and second embodiments, the above-described non-linearity is stored in the EEPROM of the storage circuit 24 of the measurement unit 5 provided in each of the strain gauge transducers 1 and 50. The correction data is stored and held in advance,
When the “measurement start instruction data” is received, the A / D
For the digital data of the strain measurement signal output from the converter 22 or the digital data obtained by performing temperature correction on the digital data, the data obtained by performing the non-linearity correction on the basis of the non-linearity correction data is measured. It is effective to use the result data.

In the strain gauge type transducer 1 according to the first embodiment and the strain gauge type transducer 50 according to the second embodiment, the measuring unit 5 is integrally formed and disposed in the housing 6. However, the measuring unit 5 may be divided into appropriate blocks and arranged in the housing 6.

Next, a third embodiment of the present invention will be described with reference to FIG. Referring to FIG. 5, a measurement module 60 for a strain gauge type transducer of the present invention includes four strain gauges 3 adhered to strain body 2 and strain gauges 3.
Is connected to a strain gauge type transducer 61 (hereinafter, referred to as a conventional strain gauge type transducer) provided with a Wheatstone bridge circuit 4 formed in the integrated housing 6.

The conventional strain gauge transducer 61 and the strain gauge transducer measuring module 60 are connected via the connector 7, the module connection cable 62 and the connector 63. A constant voltage V is supplied to the Wheatstone bridge circuit 4 of the gauge type converter 61.

When the constant voltage V is applied, the Wheatstone bridge circuit 4 outputs a strain measurement signal Δe corresponding to the pressure P applied to the strain gauge transducer 61, and outputs the strain measurement signal Δe. Δe is input to the measurement module 60 for the strain gauge type transducer via the module connection cable 62.

Measurement module 6 for strain gauge transducer
The configuration of the measurement unit 5 is the same as that of the measurement unit 5 of the first embodiment shown in FIG. 2, and the circuit configuration of the measurement unit 5 is configured in an integrated small casing.

Therefore, the measuring module 60 for the strain gauge type transducer can be arranged near the conventional strain gauge type transducer 61. Thereby, the measuring module 60 for the strain gauge type transducer and the conventional strain gauge type transducer 61 can be connected with the short module connecting cable 62, and the measuring module 60 for the strain gauge type transducer is connected via the module connecting cable 62 via the module connecting cable 62. Thus, it is possible to prevent the voltage applied to the Wheatstone bridge circuit 4 of the strain gauge type transducer 61 from being reduced due to the resistance of the module connection cable.

While the strain measurement signal Δe output from the Wheatstone bridge circuit 4 of the strain gauge type transducer 61 is input to the strain gauge type transducer measuring module 60 via the module connection cable 62,
Since the influence of external noise is prevented, the measurement module 60 for the strain gauge type transducer can stably input the strain measurement signal Δe.

By connecting the measuring module 60 for the strain gauge type transducer to the conventional strain gauge type transducer 61, the same operation and effect as those of the strain gauge type transducer 1 in the first embodiment can be obtained. Can be.

Therefore, according to the measuring module 60 for the strain gauge transducer of the third embodiment, the strain gauge transducer of the first embodiment can be used without any modification of the conventional strain gauge transducer 61. The same operation and effect as the container 1 can be obtained.

In the first to third embodiments, the operating power of the measuring unit 5 and the measuring module 60 for the strain gauge type transducer is measured by the measured data processing device 10.
However, a battery may be built in the strain gauge type transducers 1 and 50 and the measurement module 60 for the strain gauge type transducer as a power source of the operating power. In this case, the strain gauge type transducer 1, 50
In addition, digital data communication between the measurement module 60 for the strain gauge type transducer and the measurement data processing device 10 may be performed wirelessly.

In the first to third embodiments, the strain gauge type transducer for detecting pressure has been described.
A strain gauge type transducer for detecting another physical quantity, for example, a load or a displacement may be used.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram for multipoint measurement according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of the strain gauge transducer shown in FIG.

FIG. 3 is an overall configuration diagram for multipoint measurement according to a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of the strain gauge transducer shown in FIG.

FIG. 5 is a connection diagram of a measurement module for a strain gauge type transducer according to a third embodiment of the present invention.

[Explanation of symbols]

1, 50: strain gauge transducer, 2: strain generator, 3: strain gauge, 4: Wheatstone bridge circuit, 5: measuring unit, 6: housing, 7: connector, 8: common cable, 9: connector, 10 ... measured data processing device, 20 ...
Constant voltage circuit, 21 ... amplifier, 22 ... A / D converter, 23
... Control circuit, 24 ... Storage circuit, 25 ... Interface circuit, 26 ... Main power supply circuit, 51 ... Temperature sensor, 52 ... Switcher, 60 ... Measurement module for strain gauge type transducer,
61 ... (conventional) strain gauge transducer, 62 ... module connection cable, 63, 64 ... connector

Claims (10)

[Claims] 1. An integrated housing comprising a strain body to which a strain gauge is adhered, and a Wheatstone bridge circuit constituted by the strain gauge and outputting a strain measurement signal corresponding to a strain amount of the strain body to the outside. An A / D for converting the strain measurement signal into digital data in a strain gauge type transducer arranged in a body.
A transducer and a data communication processing means for subjecting the digital data as it is or performing a predetermined process, and transmitting the digital data as measurement result data to an external measurement data processing device, wherein the strain gauge type is provided in the housing. converter. 2. A temperature sensor for detecting a temperature of the flexure element, wherein the A / D converter has a function of converting a temperature detection signal output from the temperature sensor into digital data,
The data communication processing means has a function of transmitting digital data of the temperature detection signal generated by the A / D converter to the measurement data processing device as temperature detection data. Strain gauge transducer. 3. A temperature sensor for detecting a temperature of the strain body, wherein the A / D converter has a function of converting a temperature detection signal output from the temperature sensor into digital data,
The data communication processing means corrects digital data of the strain measurement signal based on digital data of the temperature detection signal generated by the A / D converter in the predetermined processing. Item 7. A strain gauge transducer according to item 1. 4. The data communication processing means according to claim 1, wherein the predetermined processing corrects a non-linearity of an output level of the distortion measurement signal in accordance with an amount of distortion of the flexure element. The strain gauge transducer according to any one of claims 1 to 3. 5. The data communication processing means has an identification code uniquely set according to the strain gage applied transducer provided with the data communication processing means, and is transmitted from the measurement data processing device. And a function of receiving output instruction data corresponding to the identification code, and transmitting the measurement result data to the measurement data processing device in response to receiving the output instruction data.
The strain gauge type transducer according to any one of the above. 6. The data communication processing means includes storage means for holding the measurement result data, and has a function of receiving measurement start instruction data transmitted from the measurement data processing device. A when the data is received
The measurement result data based on the output of the / D converter is stored in the storage unit, and the stored measurement result data is transmitted to the measurement data processing device in response to receiving the output instruction data. The strain gauge transducer according to claim 5, wherein 7. A strain generating body to which a strain gauge is adhered, and comprising a strain gauge, externally supplied with operating power and outputting a strain measurement signal corresponding to a strain amount of the strain generating body to the outside. And a Wheatstone bridge circuit, which can be connected in close proximity to a strain gauge type transducer arranged in an integral housing, and converts the strain measurement signal output from the strain gauge type transducer into digital data. A strain gauge comprising: a D converter; and a data communication processing means for transmitting the digital data as it is or by performing a predetermined process as measurement result data to an external measurement data processing device. Measurement module for type converter. 8. The data communication processing means according to claim 7, wherein the predetermined processing corrects a nonlinearity of an output level of the distortion measurement signal in accordance with an amount of distortion of the flexure element. The measurement module for a strain gauge type transducer according to the above. 9. The data communication processing means has an identification code uniquely set according to the strain gage transducer measuring module provided with the data communication processing means, and transmits the data from the measurement data processing device. 8. A function of receiving output instruction data corresponding to the identification code to be performed, and transmitting the measurement result data to the measurement data processing device in response to receiving the output instruction data. 9. The measurement module for a strain gauge transducer according to 8. 10. The data communication processing means includes a storage means for holding the measurement result data, and has a function of receiving measurement start instruction data transmitted from the measurement data processing device. The measurement result data based on the output of the A / D converter when data is received is stored in the storage unit, and the held measurement result data is stored in the measurement data processing device in response to receiving the output instruction data. The measurement module for a strain gauge type transducer according to claim 9, wherein the measurement module is transmitted to the measuring module.