Temperature measurement device and correction method

Abstract

To provide a temperature measurement device and a correction method capable of correctly measuring resistance of a resistor which is a reference in correction of a temperature measurement device.SOLUTION: The invention is configured so that, in a state of connecting first wiring 101, second wiring 102 and third wiring 103 to an inspection resistor 150, a first constant current having a current value I is supplied to the first wiring 101, a second constant current is not supplied to the second wiring 102, a first inspection voltage which is generated between the first wiring 101 and the third wiring 103, and a second inspection voltage which is generated between the second wiring 102 and the third wiring 103, are measured, then the second constant current having a current value I is supplied to the second wiring 102, then, a third inspection voltage which is generated between the first wiring 101 and the third wiring 103 and a fourth inspection voltage which is generated between the second wiring 102 and the third wiring 103 are measured without supplying the first constant current to the first wiring 101.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a temperature measuring device and a correction method. [Background technology]

[0002] A commonly used configuration for temperature measurement devices in factories, buildings, etc. is to use Pt as a resistance temperature detector, and to connect the sensor unit using the resistance temperature detector and the temperature measurement device with three wires. A first wire is connected to one end of the resistance temperature detector, and a second wire and a third wire are connected to the other end of the resistance temperature detector, and a specific calculation is performed to correct and cancel the wiring resistance component, thereby achieving a highly accurate temperature measurement function (Patent Document 1).

[0003] In the resistance measurement for compensating for the wiring resistance component, the temperature measuring device is connected to an inspection device equipped with a digital resistor that outputs an accurate resistance value, and the resistance of the reference digital resistor is measured. In this resistance measurement, a predetermined inspection current I (e.g., 1 mA) is simultaneously passed through the first wiring and the second wiring, and the voltage V1 between the first wiring and the third wiring is measured, and the voltage V2 between the second wiring and the third wiring is measured.

[0004] Here, "V1 = (r1 + r2 + R)I + r2 × 2I" and "V2 = (r1 + r2)I + r2 × 2I." Note that r1 is the resistance value of the internal wiring to the first wiring and second wiring in the temperature measurement device, r2 is the resistance value of the first wiring, second wiring, and third wiring, and R is the resistance value of the resistance thermometer.

[0005] Subtracting V2 from V1 gives (r1+r2+R)I+r2×2I-{(r1+r2)I+r2×2I}=R·I, and R=(V1-V2)÷I gives the resistance measurement result of the digital resistor measured by the temperature measuring device. If this measurement result is 100.5Ω, the resistance value of the digital resistor is 100Ω, so the error is 0.5Ω. Therefore, set the temperature measuring device to add -0.5Ω as a correction value to the measurement value and output it as the measurement result. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-027848 A Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, the measurement of the resistance value of the digital resistor in the device body described above is premised on the premise that the wiring resistances of the first wiring, the second wiring, and the third wiring are all equal. However, for example, when performing a measurement for correction using the above-mentioned digital resistor, the connection resistances when connecting the first wiring, the second wiring, and the third wiring to the inspection device may differ from each other. In particular, when using a contact-type inspection device to perform a quick inspection, a contact resistance difference is likely to occur between the first wiring, the second wiring, and the third wiring. For this reason, the correction of the above-mentioned conventional temperature measuring device has a problem that the resistance of the reference resistor cannot be accurately measured.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to accurately measure the resistance of a resistor that serves as a reference for correcting a temperature measuring device. [Means for solving the problem]

[0009] The temperature measuring device according to the present invention comprises a first wiring connected to one end of a resistance temperature detector, a second wiring and a third wiring connected to the other end of the resistance temperature detector, a first constant current source supplying a first constant current to the first wiring, a second constant current source supplying a second constant current to the second wiring, a termination circuit that terminates and connects the third wiring to a ground potential, a reference voltage circuit connected between the first constant current source and the first wiring and configured to generate a reference voltage whose voltage value changes depending on the current value of the first constant current, and a first differential voltage generated between the first wiring and the second wiring based on the reference voltage. a processing circuit configured to obtain a temperature measuring resistance value of the resistance temperature detector based on a conversion result of the first differential voltage output from the AD converter and to correct the obtained temperature measuring resistance value with the correction value to calculate a detected temperature; and a first measurement circuit configured to measure a first inspection voltage generated between the first wiring and the third wiring and a second inspection voltage generated between the second wiring and the third wiring in a first inspection measurement mode in which a first constant current is supplied to the first wiring and a second constant current is not supplied to the second wiring. a second measurement circuit configured to measure a third inspection voltage generated between the first wiring and the third wiring and a fourth inspection voltage generated between the second wiring and the third wiring in a second inspection measurement mode in which a second constant current is supplied to the second wiring and a first constant current is not supplied to the first wiring; a first calculation circuit configured to obtain a first wiring resistance of the first wiring and a second wiring resistance of the second wiring from the first inspection voltage, the second inspection voltage, the third inspection voltage, and the fourth inspection voltage; The test circuit includes a third measurement circuit configured to measure a fifth test voltage generated between the first wiring and the third wiring and a sixth test voltage generated between the second wiring and the third wiring in a third test measurement mode; a second arithmetic circuit configured to determine a measured resistance value of the test resistor connected to the first wiring, the second wiring, and the third wiring using the first wiring resistance, the second wiring resistance, the fifth test voltage, and the sixth test voltage; and a third arithmetic circuit configured to determine a difference between the measured resistance value and a known resistance value of the test resistor as a correction value and set the correction value in a memory circuit.

[0010] In one configuration example of the above-mentioned temperature measuring device, the first measurement circuit, the second measurement circuit, and the third measurement circuit perform measurements in a state in which the first wiring is connected to one end of the testing resistor, and the second wiring and the third wiring are connected to the other end of the testing resistor.

[0011] A correction method according to the present invention includes a first wiring connected to one end of a resistance temperature sensor, a second wiring and a third wiring connected to the other end of the resistance temperature sensor, a first constant current source supplying a first constant current to the first wiring, a second constant current source supplying a second constant current to the second wiring, a termination circuit connecting the third wiring to a ground potential, a reference voltage circuit connected between the first constant current source and the first wiring and generating a reference voltage whose voltage value changes according to the current value of the first constant current, and an analog-to-digital converter (ADC) for converting a first differential voltage generated between the first wiring and the second wiring based on the reference voltage. A method for correcting a temperature measuring device for measuring a detected temperature of a resistance temperature detector, the temperature measuring device comprising: a D converter; and a processing circuit for calculating a detected temperature by obtaining a temperature measuring resistance value of the resistance temperature detector based on a conversion result of a first differential voltage output from an AD converter, the method comprising the steps of: in a first inspection measurement mode in which a first wiring, a second wiring, and a third wiring are connected to a test resistor having a known resistance value, a first constant current is supplied to the first wiring, and a second constant current is not supplied to the second wiring; a second step of measuring a third inspection voltage generated between the first wiring and the third wiring and a fourth inspection voltage generated between the second wiring and the third wiring in a second inspection measurement mode in which a second constant current is supplied to the second wiring and the first constant current is not supplied to the first wiring while the first wiring, second wiring, and third wiring are connected to the inspection resistor; a third step of determining a first wiring resistance of the first wiring and a second wiring resistance of the second wiring from the first inspection voltage, the second inspection voltage, the third inspection voltage, and the fourth inspection voltage; In a third inspection measurement mode in which a first constant current is supplied to the first wiring and a second constant current is supplied to the second wiring while the line, the second wiring, and the third wiring are connected, the method includes a fourth step of measuring a fifth inspection voltage generated between the first wiring and the third wiring and a sixth inspection voltage generated between the second wiring and the third wiring, a fifth step of determining a measured resistance value of the inspection resistor using the first wiring resistance, the second wiring resistance, the fifth inspection voltage, and the sixth inspection voltage, and a sixth step of determining a difference between the measured resistance value and a known resistance value of the inspection resistor as a correction value.

[0012] In one configuration example of the above correction method, the temperature measuring device includes a memory circuit configured to store a correction value, and the processing circuit determines the temperature measuring resistance value of the resistance temperature detector based on the conversion result of the first differential voltage output from the AD converter, and corrects the determined temperature measuring resistance value with the correction value to calculate the detected temperature. Effect of the Invention

[0013] As described above, according to the present invention, voltage measurements are performed in a first inspection and measurement mode in which a first constant current is supplied to the first wiring and a second constant current is not supplied to the second wiring, and a second inspection and measurement mode in which a second constant current is supplied to the second wiring and a first constant current is not supplied to the first wiring, so that the resistance of the resistor that serves as a reference for correcting the temperature measuring device can be accurately measured. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing the configuration of a temperature measuring device 100 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart illustrating a correction method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A temperature measuring device 100 according to an embodiment of the present invention will be described below with reference to Fig. 1. The temperature measuring device 100 includes a first wiring 101, a second wiring 102, a third wiring 103, a first constant current source 104, a second constant current source 105, a termination circuit 106, a reference voltage circuit 107, an AD converter 108, a memory circuit 109, a processing circuit 110, a first measurement circuit 111, a second measurement circuit 112, a third measurement circuit 113, a first arithmetic circuit 114, a second arithmetic circuit 115, and a third arithmetic circuit 116.

[0016] The first wiring 101 is connected to one end of a resistance temperature detector used for temperature measurement, and the second wiring 102 and the third wiring 103 are connected to the other end of the resistance temperature detector. In an inspection for correcting the temperature measuring device 100, the first measuring circuit 111, the second measuring circuit 112, and the third measuring circuit 113 are configured such that the first wiring 101 is connected to one end of the inspection resistor 150, and the second wiring 102 and the third wiring 103 are connected to the other end of the inspection resistor 150. In this state, the resistance value of the inspection resistor 150 for inspection is measured. The inspection resistor 150 is a resistor that outputs a known resistance value, such as a digital resistor.

[0017] The first constant current source 104 supplies a first constant current to the first wiring 101, and the second constant current source 105 supplies a second constant current to the second wiring 102. The termination circuit 106 terminates and connects the third wiring 103 to a ground potential. The reference voltage circuit 107 is connected between the first constant current source 104 and the first wiring 101, and generates a reference voltage whose voltage value changes according to the current value of the first constant current.

[0018] The AD converter 108 performs AD conversion on a first differential voltage occurring between the first wiring 101 and the second wiring 102 based on the reference voltage. The memory circuit 109 stores the correction value. The processing circuit 110 obtains a temperature measuring resistance value of the resistance temperature detector based on the conversion result of the first differential voltage output from the AD converter 108, and corrects the obtained temperature measuring resistance value with the correction value to calculate the detected temperature.

[0019] In a first inspection measurement mode in which a first constant current I is supplied to the first wiring 101 and a second constant current is not supplied to the second wiring 102, the first measurement circuit 111 measures a first inspection voltage generated between the first wiring 101 and the third wiring 103, and a second inspection voltage generated between the second wiring 102 and the third wiring 103.

[0020] In a second inspection measurement mode in which a second constant current I is supplied to the second wiring 102 and a first constant current is not supplied to the first wiring 101, the second measurement circuit 112 measures a third inspection voltage generated between the first wiring 101 and the third wiring 103, and a fourth inspection voltage generated between the second wiring 102 and the third wiring 103.

[0021] The first arithmetic circuit 114 determines a first wiring resistance r2 of the first wiring 101 and a second wiring resistance r3 of the second wiring 102 from the first inspection voltage, the second inspection voltage, the third inspection voltage, and the fourth inspection voltage.

[0022] In a third inspection measurement mode in which a first constant current is supplied to the first wiring 101 and a second constant current is supplied to the second wiring 102, the third measurement circuit 113 measures a fifth inspection voltage generated between the first wiring 101 and the third wiring 103, and a sixth inspection voltage generated between the second wiring 102 and the third wiring 103.

[0023] The second arithmetic circuit 115 uses the first wiring resistance r2, the second wiring resistance r3, the fifth inspection voltage, and the sixth inspection voltage to determine the measured resistance value R' of the inspection resistor 150 connected to the first wiring 101, the second wiring 102, and the third wiring 103.

[0024] The third arithmetic circuit 116 determines the difference between the measured resistance value R′ and the known resistance value R of the testing resistor 150 as a correction value, and sets the correction value in the memory circuit 109 .

[0025] Next, a correction method according to an embodiment of the present invention will be described with reference to Fig. 2. This correction method is a correction method for temperature measuring device 100.

[0026] First, in a first step S101, with the first wiring 101, the second wiring 102, and the third wiring 103 connected to the inspection resistor 150 whose resistance value is known, a first constant current of current value I is supplied to the first wiring 101 and a second constant current is not supplied to the second wiring 102. In a first inspection measurement mode, the first measurement circuit 111 measures a first inspection voltage V1 generated between the first wiring 101 and the third wiring 103, and a second inspection voltage V2 generated between the second wiring 102 and the third wiring 103.

[0027] Next, in a second step S102, with the first wiring 101, the second wiring 102, and the third wiring 103 connected to the inspection resistor 150, a second constant current of current value I is supplied to the second wiring 102 and the first constant current is not supplied to the first wiring 101 in a second inspection measurement mode, in which the second measurement circuit 112 measures a third inspection voltage V1' generated between the first wiring 101 and the third wiring 103, and a fourth inspection voltage V2' generated between the second wiring 102 and the third wiring 103.

[0028] Next, in a third step S103, the first arithmetic circuit 114 calculates the first wiring resistance r2 of the first wiring 101 and the second wiring resistance r3 of the second wiring 102 from the first inspection voltage V1, the second inspection voltage V2, the third inspection voltage V1', and the fourth inspection voltage V2'.

[0029] Here, "V1 = (r1 + r2 + R + r4) I" and "V2 = r4 × I". Also, "V1' = r4 × I" and "V2' = (r1 + r3 + r4) I". Therefore, "r2 = (V1 - V2) ÷ I - (r1 + R)" and "r3 = (V2' - V1') ÷ I - r1" are obtained, and if the first inspection voltage V1, the second inspection voltage V2, the third inspection voltage V1', and the fourth inspection voltage V2' are measured, the first wiring resistance r2 and the second wiring resistance r3 can be obtained. Note that r1 is the resistance value of the internal wiring to the first wiring 101 and the second wiring 102 inside the temperature measuring device 100, and is known. Also, r4 is the third wiring resistance of the third wiring 103. Also, R is the resistance value of the inspection resistor 150, and is known.

[0030] Next, in a fourth step S104, with the first wiring 101, the second wiring 102, and the third wiring 103 connected to the inspection resistor 150, a first constant current of current value I is supplied to the first wiring 101 and a second constant current of current value I is supplied to the second wiring 102. In a third inspection measurement mode, the third measurement circuit 113 measures a fifth inspection voltage V1" generated between the first wiring 101 and the third wiring 103, and a sixth inspection voltage V2" generated between the second wiring 102 and the third wiring 103.

[0031] Next, in a fifth step S105, the second arithmetic circuit 115 determines the measured resistance value R' of the test resistor 150 using the first wiring resistance r2, the second wiring resistance r3, the fifth test voltage V1'', and the sixth test voltage V2''.

[0032] Here, since "V1" = (r1 + r2 + R') + r4 × 2I" and "V2" = (r1 + r3) × I + r4 × 2I", it follows that "R' = (V1" - V2") ÷ I + (r2 - r3)". If the first wiring resistance r2 and the second wiring resistance r3 have been determined, the measured resistance value R' of the inspection resistor 150 can be determined from the measured fifth inspection voltage V1" and sixth inspection voltage V2".

[0033] Next, in a sixth step S106, the third arithmetic circuit 116 determines the difference between the measured resistance value R' and the known resistance value R of the testing resistor 150 as a correction value. The determined correction value is stored in the memory circuit 109. In actual measurement by the temperature measuring device 100, the processing circuit 110 uses the correction value stored in the memory circuit 109 as described above to determine the temperature measuring resistance of the temperature measuring resistor based on the conversion result of the first differential voltage output from the AD converter 108, and corrects the determined temperature measuring resistance value with the correction value to calculate the detected temperature.

[0034] As described above, according to the embodiment, the first wiring resistance r2 of the first wiring 101 and the second wiring resistance r3 of the second wiring 102 are obtained, so that even if the connection resistances when the first wiring 101, the second wiring 102, and the third wiring 103 are connected to the inspection device are different from one another, it becomes possible to accurately measure the resistance value of the inspection resistor 150.

[0035] As described above, according to the present invention, voltage measurements are performed in each of a first inspection and measurement mode in which a first constant current is supplied to the first wiring and a second constant current is not supplied to the second wiring, and a second inspection and measurement mode in which a second constant current is supplied to the second wiring and a first constant current is not supplied to the first wiring, so that the resistance of the resistor that serves as a reference for correcting the temperature measuring device can be accurately measured.

[0036] It should be noted that the present invention is not limited to the above-described embodiments, and it is apparent that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention. [Explanation of symbols]

[0037] 101...first wiring, 102...second wiring, 103...third wiring, 104...first constant current source, 105...second constant current source, 106...termination circuit, 107...reference voltage circuit, 108...AD converter, 109...memory circuit, 110...processing circuit, 111...first measurement circuit, 112...second measurement circuit, 113...third measurement circuit, 114...first arithmetic circuit, 115...second arithmetic circuit, 116...third arithmetic circuit, 150...test resistor.

Claims

1. A first wire connected to one end of the resistance temperature sensor, and a second wire and a third wire connected to the other end of the resistance temperature sensor; a first constant current source that supplies a first constant current to the first wiring; a second constant current source that supplies a second constant current to the second wiring; a termination circuit that terminates and connects the third wiring to a ground potential; a reference voltage circuit connected between the first constant current source and the first wiring and configured to generate a reference voltage whose voltage value changes according to a current value of the first constant current; an AD converter that performs AD conversion on a first differential voltage generated between the first wiring and the second wiring based on the reference voltage; a storage circuit configured to store the correction value; a processing circuit configured to obtain a temperature measuring resistance value of the temperature measuring resistor based on a conversion result of the first differential voltage output from the AD converter, and to calculate a detection temperature by correcting the obtained temperature measuring resistance value with the correction value; a first measurement circuit configured to measure a first inspection voltage generated between the first wiring and the third wiring and a second inspection voltage generated between the second wiring and the third wiring in a first inspection and measurement mode in which the first constant current is supplied to the first wiring and the second constant current is not supplied to the second wiring; a second measurement circuit configured to measure a third inspection voltage generated between the first wiring and the third wiring and a fourth inspection voltage generated between the second wiring and the third wiring in a second inspection measurement mode in which the second constant current is supplied to the second wiring and the first constant current is not supplied to the first wiring; a first arithmetic circuit configured to calculate a first wiring resistance of the first wiring and a second wiring resistance of the second wiring from the first inspection voltage, the second inspection voltage, the third inspection voltage, and the fourth inspection voltage; a third measurement circuit configured to measure a fifth inspection voltage generated between the first wiring and the third wiring and a sixth inspection voltage generated between the second wiring and the third wiring in a third inspection measurement mode in which the first constant current is supplied to the first wiring and the second constant current is supplied to the second wiring; a second arithmetic circuit configured to determine a measured resistance value of a test resistor connected to the first wiring, the second wiring, and the third wiring, using the first wiring resistance, the second wiring resistance, the fifth test voltage, and the sixth test voltage; a third arithmetic circuit configured to obtain a difference between the measured resistance value and a known resistance value of the resistor under test as the correction value and set the correction value in the memory circuit; A temperature measuring device comprising:

2. 2. The temperature measuring device according to claim 1, The first measurement circuit, the second measurement circuit, and the third measurement circuit are a temperature measuring device that performs measurements in a state in which the first wiring is connected to one end of the testing resistor, and the second wiring and the third wiring are connected to the other end of the testing resistor.

3. A first wire connected to one end of the resistance temperature sensor, and a second wire and a third wire connected to the other end of the resistance temperature sensor; a first constant current source that supplies a first constant current to the first wiring; a second constant current source that supplies a second constant current to the second wiring; a termination circuit that terminates and connects the third wiring to a ground potential; a reference voltage circuit connected between the first constant current source and the first wiring, the reference voltage circuit generating a reference voltage whose voltage value changes in response to a current value of the first constant current; an AD converter that performs AD conversion on a first differential voltage generated between the first wiring and the second wiring based on the reference voltage; a processing circuit for determining a temperature measuring resistance value of the temperature measuring resistor based on a conversion result of the first differential voltage output from the AD converter and calculating a detected temperature; A method for correcting a temperature measuring device for measuring a detected temperature of the resistance temperature detector, comprising: a first step of measuring a first inspection voltage generated between the first wiring and the third wiring and a second inspection voltage generated between the second wiring and the third wiring in a first inspection measurement mode in which the first constant current is supplied to the first wiring and the second constant current is not supplied to the second wiring, with the first wiring, the second wiring, and the third wiring being connected to an inspection resistor having a known resistance value; a second step of measuring a third inspection voltage generated between the first wiring and the third wiring and a fourth inspection voltage generated between the second wiring and the third wiring in a second inspection measurement mode in which the second constant current is supplied to the second wiring and the first constant current is not supplied to the first wiring while the first wiring, the second wiring, and the third wiring are connected to the inspection resistor; a third step of determining a first wiring resistance of the first wiring and a second wiring resistance of the second wiring from the first inspection voltage, the second inspection voltage, the third inspection voltage, and the fourth inspection voltage; a fourth step of measuring a fifth inspection voltage generated between the first wiring and the third wiring and a sixth inspection voltage generated between the second wiring and the third wiring in a third inspection and measurement mode in which the first constant current is supplied to the first wiring and the second constant current is supplied to the second wiring while the first wiring, the second wiring, and the third wiring are connected to the inspection resistor; a fifth step of determining a measured resistance value of the test resistor using the first wiring resistance, the second wiring resistance, the fifth test voltage, and the sixth test voltage; a sixth step of determining a difference between the measured resistance value and a known resistance value of the resistor under test as a correction value; A correction method comprising:

4. 4. The correction method according to claim 3, the temperature measurement device includes a memory circuit configured to store the correction value; A correction method in which the processing circuit calculates the temperature sensing resistance value of the resistance temperature detector based on the conversion result of the first differential voltage output from the AD converter, and corrects the calculated temperature sensing resistance value with the correction value to calculate the detected temperature.

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