Method for calibrating a temperature measuring device, a calibration device for a temperature measuring device, and a temperature measuring device and a current-voltage measuring device.

Abstract

To provide a calibration method for a temperature measuring device that can improve measurement accuracy. [Solution] A method for calibrating a temperature measuring device, comprising: detecting a calibration short-circuit current by short-circuiting a reference contact; detecting a calibration open-circuit voltage by opening the reference contact under the same conditions as in the step of detecting the calibration short-circuit current, where the temperature at the measurement position and the reference temperature are the same; calculating the current-indicated temperature difference between the temperature measuring contact and the reference contact from the calibration short-circuit current using a preset current-temperature conversion formula; calculating the voltage-indicated temperature difference between the temperature measuring contact and the reference contact from the calibration open-circuit voltage using a preset voltage-temperature conversion formula; and calculating a correction coefficient, which is multiplied by the temperature difference derived by the current-temperature conversion formula during normal measurement, as the ratio of the voltage-indicated temperature difference to the current-indicated temperature difference.

Description

Technical Field

[0001] The present invention relates to a temperature measuring device calibration method, a temperature measuring device calibration apparatus, a temperature measuring device, and a current-voltage measuring device.

Background Art

[0002] As an element for detecting temperature, a thermocouple that generates an electromotive force according to the temperature difference between two contacts formed of dissimilar metals is widely used. Generally, the electromotive force generated by the temperature difference is detected as a voltage, but the sensitivity (resolution) may be insufficient in voltage detection. For example, in a heating type AC current-voltage sensor that measures the effective value of current or voltage by converting electric power into heat with a resistor or the like and measuring the temperature change due to the heat, high accuracy may be required for temperature measurement. In order to improve the detection sensitivity, a technique of short-circuiting a thermocouple and detecting a short-circuit current has also been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When detecting the short-circuit current of a thermocouple, Joule heat and Peltier heat are generated by flowing a current, resulting in a measurement error. As a method for compensating for such a measurement error caused by flowing a current, in Patent Document 1, in a state where a temperature difference is generated by heating means between the hot junction and the cold junction of a calibration thermocouple formed of the same thermocouple material as the detection thermocouple in advance, the absolute thermoelectric energy of the calibration thermocouple is measured, and the internal resistance near the measured temperature of the thermocouple is measured, and it is proposed to calculate the measured temperature difference using the absolute thermoelectric energy and the internal resistance. However, accurate measurement of thermoelectric energy is not easy, and a method that can measure temperature with higher accuracy is desired.

[0005] Therefore, the object of the present invention is to provide a temperature measuring device calibration method and a temperature measuring device calibration device that can improve measurement accuracy, as well as a temperature measuring device and a current-voltage measuring device. [Means for solving the problem]

[0006] A method for calibrating a temperature measuring device according to one aspect of the present invention is a method for calibrating a temperature measuring device that uses a thermocouple having a temperature measuring junction placed at a measurement position and a reference junction held at a reference temperature, detects a short-circuit current flowing through the thermocouple when the reference junction is short-circuited, and calculates the temperature of the temperature measuring junction by deriving the temperature difference between the temperature measuring junction and the reference junction using a preset current-temperature conversion formula, comprising the steps of: detecting a calibration short-circuit current when the reference junction is short-circuited; detecting a calibration open-circuit voltage when the reference junction is opened under the same conditions as in the step of detecting the calibration short-circuit current; calculating the current-indicated temperature difference between the temperature measuring junction and the reference junction from the calibration short-circuit current using the current-temperature conversion formula; calculating the voltage-indicated temperature difference between the temperature measuring junction and the reference junction from the calibration open-circuit voltage using a preset voltage-temperature conversion formula; and calculating a correction coefficient multiplied by the temperature difference derived by the current-temperature conversion formula during normal measurement as the ratio of the voltage-indicated temperature difference to the current-indicated temperature difference.

[0007] The above-described method for calibrating a temperature measuring device may further include a step of deriving the temperature of the temperature measuring junction from the current-indicated temperature difference, the reference temperature, and the performance index, which is an intrinsic value of the thermocouple.

[0008] A temperature measuring device calibration device according to another aspect of the present invention is a temperature measuring device calibration device that uses a thermocouple having a temperature measuring junction placed at a measurement position and a reference junction held at a reference temperature, detects a short-circuit current flowing through the thermocouple when the reference junction is short-circuited, and calculates the temperature of the temperature measuring junction by deriving the temperature difference between the temperature measuring junction and the reference junction using a preset current-temperature conversion formula, comprising: a current-indicated temperature difference calculation unit that calculates the current-indicated temperature difference between the temperature measuring junction and the reference junction using the current-temperature conversion formula from the calibration short-circuit current detected by short-circuiting the reference junction; a voltage-indicated temperature difference calculation unit that calculates the voltage-indicated temperature difference between the temperature measuring junction and the reference junction using a preset voltage-temperature conversion formula from the calibration open-circuit voltage detected when the reference junction is opened under the condition that the temperature at the measurement position and the reference temperature are the same as when the calibration short-circuit current is detected; and a correction coefficient calculation unit that calculates a correction coefficient to be multiplied by the temperature difference derived by the current-temperature conversion formula during normal measurement as the ratio of the voltage-indicated temperature difference to the current-indicated temperature difference.

[0009] Another aspect of the present invention provides a temperature measuring device comprising a thermocouple having a temperature measuring junction positioned at a measurement location and a reference junction held at a reference temperature, and a switching circuit that short-circuits or opens the reference junctions, inserting a current detector between the reference junctions when short-circuited and a voltage detector between the reference junctions when open.

[0010] A current-voltage measuring device according to yet another aspect of the present invention comprises a heating circuit that generates heat in response to input power, the above-described temperature measuring device which is positioned at the location into which the heat generated by the heating circuit flows as the measurement position, and a current detector inserted between the reference contacts by the switching circuit.

[0011] In the current-voltage measuring device described above, the current detector may include a coil that generates a magnetic field due to the short-circuit current when the reference contact is short-circuited, and a magnetic field detector that detects the magnetic field generated by the coil. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a temperature measuring device calibration method and a temperature measuring device calibration device that can improve measurement accuracy, as well as a temperature measuring device and a current-voltage measuring device. [Brief explanation of the drawing]

[0013] [Figure 1] This is a circuit diagram showing the configuration of a temperature measuring device according to one embodiment of the present invention. [Figure 2] Figure 1 is a flowchart showing the procedure for calibrating the temperature measuring device. [Figure 3] This is a circuit diagram showing the configuration of a current and voltage measuring device relating to one embodiment of the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings. In the descriptions of embodiments described later, components similar to those described in earlier embodiments will be denoted by the same reference numerals, and redundant explanations will be omitted. Also, the dimensions of various components in the drawings have been adjusted for ease of viewing.

[0015] [Temperature measurement device] Figure 1 is a circuit diagram showing the configuration of a temperature measuring device 1 according to one embodiment of the present invention. The temperature measuring device 1 comprises a thermocouple 10, a switching circuit 20, a current detector 30, a voltage detector 40, and a calculation device 50.

[0016] The thermocouple 10 has a temperature sensing junction 11 placed at the measurement position and a reference junction 12 maintained at a reference temperature, and generates a thermoelectric voltage according to the temperature difference between the temperature sensing junction 11 and the reference junction 12. The thermocouple 10 is formed from two types of metal wires, and the temperature sensing junction 11 and the reference junction 12 are junctions that join the ends of the two types of metal wires. The reference temperature may be strictly maintained by a constant temperature bath such as an ice bath, or it may be a rough temperature that is sufficiently small in variation compared to the temperature at the measurement position, such as room temperature.

[0017] The switching circuit 20 short-circuits or opens the reference contact 12, inserting a current detector 30 between the reference contacts 12 when short-circuited, and inserting a voltage detector 40 between the reference contacts 12 when open. For this reason, the switching circuit 20 may be configured to have a switching switch 21 as shown in the figure, but it may also be configured so that the user can insert the current detector 30 or the voltage detector 40 between the reference contacts 12 by rewiring, for example, using a connector, terminal block, etc. In order to reduce measurement errors, it is preferable that the switching circuit 20 be formed using a material with low electrical resistance and low thermal conductance with the outside, such as thin copper wire, as the wiring material.

[0018] The current detector 30 is inserted between the reference contacts 12 to short-circuit the reference contacts 12 and detects the short-circuit current flowing through the thermocouple 10 when the reference contacts 12 are short-circuited (the short-circuit current during normal measurement and the calibration short-circuit current for calibration). Preferably, the short-circuit current is measured after waiting a few minutes after short-circuiting the reference contacts 12 and allowing the heat generated by the short-circuit current to reach equilibrium. The current detector 30 may use an operational amplifier or the like to amplify the short-circuit current, but preferably it is a magnetic conversion detection type current detector having a coil that generates a magnetic field due to the short-circuit current when the reference contacts 12 are short-circuited, and a magnetic field detector that detects the magnetic field generated by the coil. As the magnetic field detector, for example, a Hall element, a SUQUID magnetic sensor, or an NV diamond magnetic sensor may be used. By using a magnetic conversion detection type current detector with almost no voltage drop, high-resolution, high-precision current detection and, consequently, high-precision temperature measurement become possible.

[0019] The voltage detector 40 is inserted between the reference contacts 12, thereby opening the reference contacts 12, and detects the open-circuit voltage of the thermocouple 10 when the reference contacts 12 are open. The voltage detector can be appropriately selected from well-known types.

[0020] During normal measurement, the arithmetic unit 50 uses a preset current-temperature conversion formula to derive the temperature difference between the temperature measurement contact 11 and the reference contact 12 from the short-circuit current detected by the current detector 30, and multiplies it by a correction factor C set by calibration described later to calculate the temperature of the temperature measurement contact 11 (relative temperature with respect to the reference temperature). The measured temperature calculation unit 51 may further calculate the actual temperature by adding the reference temperature to the relative temperature of the temperature of the temperature measurement contact 11. The arithmetic unit 50 may be realized by a dedicated wiring circuit, a dedicated integrated circuit, etc., or may be realized by a programmable controller, a general-purpose computer device, etc. The arithmetic unit 50 may further have a function of controlling the operation of the changeover switch 21. Also, the arithmetic unit 50 may be integrated with arithmetic units such as the current detector 30 and the voltage detector 40, or may be integrally configured with the control device of the system in which the temperature measurement device 1 is incorporated.

[0021] The measured temperature calculation unit 51 uses as the measured value of the temperature difference between the temperature measurement contact 11 and the reference contact 12 the value obtained by multiplying the temperature difference ΔTs [K] between the temperature measurement contact 11 and the reference contact 12, which is obtained by converting the short-circuit current by the current-temperature conversion formula, by the correction factor C. The current conversion formula is a theoretical formula for the Seebeck effect that does not take into account the effects of Joule heat and Peltier heat. With the internal resistance of the thermocouple 10 being R [Ω], the Seebeck coefficient being S [V / K], and the short-circuit current being Is [A], it is expressed as ΔTs = RIs / S ··· (1).

[0022] The arithmetic unit 50 further functions as a temperature measurement device calibration device for calibrating the temperature measurement device 1, and is interpreted as an embodiment of the temperature measurement device calibration device according to the present invention. The arithmetic unit 50 as the temperature measurement device calibration device includes a current indication temperature difference calculation unit 52, a voltage indication temperature difference calculation unit 53, a correction coefficient calculation unit 54, and a measurement position temperature calculation unit 55, and calculates a correction coefficient C for calibrating the temperature measurement device 1 and the temperature Th [K] of the measurement position. The current indication temperature difference calculation unit 52 converts the value of the calibration short-circuit current detected by short-circuiting the reference contact 12 into the current indication temperature difference ΔTsc [K], which is the temperature difference between the temperature measurement contact 11 and the reference contact 12, by using a current-temperature conversion formula. The voltage indication temperature difference calculation unit 53 converts the value of the calibration open voltage ΔToc detected by opening the reference contact 12 under the condition that the temperature Th of the measurement position and the reference temperature Tc [K] are the same as those at the time of detecting the calibration short-circuit current into the voltage indication temperature difference ΔToc [K], which is the temperature difference between the temperature measurement contact 11 and the reference contact 12, by using a preset voltage-temperature conversion formula. The correction coefficient calculation unit 54 calculates the correction coefficient C, which is multiplied by the current indication temperature difference ΔTsc derived by the current-temperature conversion formula during normal measurement (measurement for detecting the temperature of the measurement position rather than measurement for calibration), as the ratio of the voltage indication temperature difference ΔToc [K] to the current indication temperature difference ΔTsc. The measurement position temperature calculation unit 55 derives the temperature Th of the measurement position from the current indication temperature difference ΔTsc, the reference temperature Tc, and the performance index z, which is a characteristic value of the thermocouple 10. The voltage-temperature conversion formula is a theoretical formula for the Seebeck effect. When the open voltage of the thermocouple 10 is Vo, it is expressed as ΔToc = Vo / S ··· (2). The arithmetic unit 50 may be configured to operate the switching circuit 20 at a predetermined timing, for example, every fixed time, to calculate the correction coefficient C.

[0023] More specifically, the heat flow Q [W] from the measurement position (around the temperature sensing junction 11) to the thermocouple 10 is expressed as Q = K·ΔTo···(3), where K [W / K] is the thermal conductance of the thermocouple 10. When the reference junction 12 is short-circuited, Peltier heat is generated at the temperature sensing junction 11 and the reference junction 12, and Joule heat is generated throughout the thermocouple 10. In a short-circuit state, the amount of heat flowing into the temperature sensing junction 11 is considered to be equal to the amount of heat flowing out from the reference junction 12. Therefore, the heat flow Q [W] when the reference junction 12 is short-circuited can be expressed as Q = [SThIs + 1 / 2·RIs2 + KΔTs]···(4) and Q = [STcIs + 1 / 2·RIs2 + KΔTs]···(5), using the temperature Th [K] of the temperature sensing junction 11 and the temperature Tc [K] of the reference junction 12.

[0024] From equations (1) to (5), the relationship between the temperature difference ΔTo when the temperature sensing junction 11 and the reference junction 12 are open and the temperature difference ΔTs when they are short-circuited can be expressed as ΔToc = ΔTsc[1 + S2 / (RK)(Th + Tc) / 2]···(6). Here, simplifying using the figure of merit (eigenvalue of thermocouple 10) z = S2 / (RK) and the mean temperature T = (Th + Tc) / 2, it can be expressed as ΔToc = ΔTsc[1 + zT]···(7). Therefore, the correction coefficient C to be multiplied by the temperature difference calculated by the current-temperature conversion formula is expressed as C = [1 + zT]···(8).

[0025] Although Joule heating does change with the temperature difference of the thermocouple 10, it flows equally into the measuring junction 11 and the reference junction 12, forming a parabolic temperature distribution. Therefore, within the range where this approximation holds, it can be said to contribute almost nothing to the temperature difference. On the other hand, Peltier heating occurs at the measuring junction 11 and the reference junction 12 of the thermocouple 10, so it contributes significantly to the temperature difference. The temperature difference ΔTo calculated from the open-circuit voltage Vo can be considered a constant multiple of the temperature difference ΔTs calculated from the short-circuit current Is. The correction coefficient C for typical industrial thermocouples is around 1.1 to 1.2, and even for special thermocouples with high sensitivity using semiconductors, the correction coefficient C is around 1.5 to 2.0. When the average temperature of the measuring junction 11 and the reference junction 12 during normal measurement does not change significantly from the average temperature T during calibration, the change in the average temperature T has almost no effect on the value of the correction coefficient C = [1 + zT]. Therefore, the correction coefficient C is determined as C = ΔToc / ΔTsc, using the current-indicated temperature difference ΔTsc and voltage-indicated temperature difference ΔToc, which are calculated from the short-circuit current Is and open-circuit voltage Vo detected under arbitrary conditions where the temperature at the measurement location and the reference temperature are the same. Furthermore, if the temperature sensing junctions 11 of two thermocouples 10 of the same specifications are placed at two different measurement locations, and the reference junction 12 is set to the same reference temperature, the ratio of the temperatures at the two measurement locations calculated from the short-circuit current of each thermocouple 10 will be constant regardless of the effect of self-heating due to the short-circuit current. Therefore, if only the ratio of the temperatures at the two measurement locations is to be known, it is not necessary to calculate the correction coefficient.

[0026] Assuming that the average temperature of the temperature measuring junction 11 and the reference junction 12 during normal measurement does not change significantly from the average temperature T during calibration, the correction coefficient C was treated as a constant. However, strictly speaking, the correction coefficient C also changes depending on Th and Tc. The voltage-indicated temperature difference ΔTo is defined as ΔTo = Th - Tc...(8) using Th and Tc. Substituting (8) into equation (7) and eliminating ΔTo, the temperature Th at the measurement position can be expressed as follows using the current-indicated temperature difference ΔTsc, the figure of performance z, and the reference temperature Tc.

[0027]

number

[0028] Equation (9) holds true even when the correction coefficient C depends on Th and Tc, and can be used as an error evaluation formula for the temperature difference obtained from the correction coefficient C = [1 + zT]. The figure of merit z included in equation (9) can be derived by calculation after determining the Seebeck coefficient, thermal conductivity, and electrical resistivity of the thermocouple, but it can also be derived by the following method. Rearranging equation (7) for the figure of merit z, we obtain z = [(ΔToc / ΔTsc) - 1] / T ... (10). Substituting the relationship T = (ΔTo + 2Tc) / 2 into equation (10) and eliminating T from equation (10), we derive the following equation (11).

[0029]

number

[0030] In other words, if the current-indicated temperature difference ΔTsc, the voltage-indicated temperature difference ΔToc, and the reference temperature Tc are measured in advance, the figure of merit z included in equation (9) can be derived from equation (11).

[0031] As described above, the temperature measuring device 1 detects the short-circuit current flowing through the thermocouple 10 with the reference contact 12 short-circuited by the switching circuit 20, and the calculation device 50 accurately calculates the temperature difference between the temperature measuring contact 11 and the reference contact 12 by multiplying the value of the temperature difference ΔTs derived from the detected value of the short-circuit current by a correction coefficient C using the current-temperature conversion formula.

[0032] Furthermore, the temperature measuring device 1 may also be calibrated using a general thermocouple calibration method to compensate for deviations caused by changes in the physical quantities of the thermocouple 10. In other words, the temperature at the measurement location and the reference temperature may be measured with a separately prepared accurate temperature detector, or the temperature at the measurement location and the reference temperature may be adjusted to predetermined temperatures in a constant temperature device, and the error in measuring the temperature at the measurement location by the temperature measuring device 1 may be checked, and the current-temperature conversion formula and voltage-temperature conversion formula may be modified to eliminate the error.

[0033] The temperature measuring device 1 is itself calibrated by the temperature measuring device configuration method according to the present invention. The calibration method for the temperature measuring device 1 is performed in the procedure shown in Figure 2. This temperature measuring device calibration method comprises a calibration short-circuit current detection step (step S1), a calibration open-circuit voltage detection step (step S2), a current-indicated temperature difference calculation step (step S3), a voltage-indicated temperature difference calculation step (step S4), and a correction coefficient calculation step (step S5). The order of the calibration short-circuit current detection step (step S1) and the calibration open-circuit voltage detection step (step S2), and the order of the current-indicated temperature difference calculation step (step S3) and the voltage-indicated temperature difference calculation step (step S4) can be interchanged.

[0034] In the calibration short-circuit current detection step (step S1), the calibration short-circuit current flowing through the thermocouple 10 is detected with the reference junction 12 short-circuited. This calibration short-circuit current detection step may utilize the last or first measured value of the short-circuit current during normal measurement immediately before or after the calibration open-circuit voltage detection step.

[0035] In the calibration short-circuit voltage detection step (step S2), the calibration open-circuit voltage, which is the voltage between the reference contacts 12 when the reference contacts 12 are opened, is detected under the condition that the temperature at the measurement location and the reference temperature are the same as in the calibration short-circuit current detection step.

[0036] In the process of calculating the current-indicated temperature difference (step S3), the current-indicated temperature difference ΔTsc, which is the theoretical temperature difference between the temperature measuring junction 11 and the reference junction 12, is calculated using the current-temperature conversion formula from the calibration short-circuit current detected in the calibration short-circuit current detection process.

[0037] In the voltage-indicated temperature difference calculation step (step S4), the voltage-indicated temperature difference ΔToc, which is the theoretical temperature difference between the temperature measuring junction 11 and the reference junction 12, is calculated using the voltage-temperature conversion formula from the calibration open-circuit voltage detected in the calibration short-circuit voltage detection step.

[0038] In the correction coefficient calculation step (step S5), the correction coefficient C, which is multiplied by the temperature difference ΔTs derived by the current-temperature conversion formula during normal measurement, is calculated as the ratio of the voltage-indicated temperature difference ΔToc to the current-indicated temperature difference ΔTsc (ΔToc / ΔTsc).

[0039] Furthermore, the temperature measuring device configuration method may include a step of deriving the temperature of the temperature measuring junction 11 from the current-indicated temperature difference ΔTsc, the reference temperature Tc, and the figure of performance z. This compensates for the offset of the measured value of the temperature measuring device 1, enabling more accurate measurements.

[0040] By performing the calibration described above, the temperature measuring device 1 will be able to accurately measure the temperature difference at the measurement location relative to the reference temperature.

[0041] [Current and Voltage Measuring Device] Figure 3 is a circuit diagram showing the configuration of a current-voltage measuring device 100 according to one embodiment of the present invention. The current-voltage measuring device 100 comprises a heating circuit 110 that generates heat in response to the input power, and the above-mentioned temperature measuring device 1 which is positioned at the location into which the heat generated by the heating circuit 110 flows, and has a current detector 30 and a voltage detector 40.

[0042] The heating circuit 110 may have a resistive heating element 111 as shown in Figure 3. Alternatively, the heating circuit 110 may be an electric heat conversion circuit that generates or absorbs heat due to the Thomson effect, which is created by a temperature difference between the upstream and downstream sides of the measurement position. An electric heat conversion circuit that utilizes the Thomson effect may be configured such that one side of the measurement position (upstream or downstream) is immersed in a constant temperature bath maintained at a predetermined high temperature, and the other side is immersed in a constant temperature bath maintained at a predetermined low temperature.

[0043] The current detector 30 preferably includes, as shown in the figure, a coil 31 that generates a magnetic field by the short-circuit current when the reference contact 12 is short-circuited, and a magnetic field detector 32 that detects the magnetic field generated by the coil 31. The magnetic field detector 32 preferably includes an NV diamond element 321 that is positioned to receive the magnetic field generated by the coil 31 so as to detect minute changes in the magnetic field, a microwave application unit 322 that applies frequency-varying microwaves to the NV diamond element 321, an excitation light irradiation unit 323 that irradiates the NV diamond element 321 with excitation light, and a fluorescence detection unit 324 that detects the intensity of fluorescence of the NV diamond element 321.

[0044] The current-voltage measuring device 100 can measure the effective value of the current or voltage applied to the heating circuit 110 by first applying a known current or voltage to the heating circuit 110 and detecting the temperature change of the thermometer junction 11 of the thermocouple 10 due to the heat generated by the heating circuit 110, thereby determining the relationship between the current or voltage applied to the heating circuit 110 and the measurement value of the temperature measuring device 1. The current-voltage measuring device 100 measures the temperature change due to the heating of the heating circuit 110 by measuring with a temperature measuring device 1 that performs measurements using a short-circuit current with high resolution and is calibrated relatively accurately by detecting a calibration short-circuit current and calibration short-circuit voltage, so it can measure the effective value of the current or voltage with high accuracy.

[0045] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications and variations are possible. For example, in the temperature measuring device according to the present invention, the calculation device may be omitted, and the user may calculate the temperature of the temperature measuring junction and the correction coefficient by hand or using a general-purpose calculator. Also, in the temperature measuring device and current-voltage measuring device according to the present invention, the voltage detector may be omitted, and a general-purpose voltage detector such as a tester may be inserted to detect the voltage when the reference junction is open. The temperature measuring device calibration device according to the present invention may be a device independent of the calculation device of the temperature measuring device. Furthermore, in the temperature measuring device calibration device, the measurement position temperature calculation unit is not essential. [Explanation of Symbols]

[0046] 1 Temperature measuring device 10 Thermocouples 11 Temperature sensing junction 12 Reference contacts 20 Switching circuit 21 Changeover switch 30 Current detector 31 coils 32 Magnetic field detectors 40 Voltage detector 50 Arithmetic device (temperature measurement device calibration device) 51 Measured temperature calculation section 52 Current indication temperature difference calculation section 53 Voltage Indication Temperature Difference Calculation Unit 54 Correction coefficient calculation unit 55 Measurement position temperature calculation section 100 Current and Voltage Measuring Device 110 Heating circuit 111 Resistive heating element 321 NV Diamond Element 322 Microwave application section 323 Excitation light irradiation section 324 Fluorescence detection unit

Claims

1. A method for calibrating a temperature measuring device, which uses a thermocouple having a temperature measuring junction placed at a measurement position and a reference junction held at a reference temperature, detects the short-circuit current flowing through the thermocouple when the reference junction is short-circuited, and calculates the temperature of the temperature measuring junction by deriving the temperature difference between the temperature measuring junction and the reference junction using a preset current-temperature conversion formula, A step of detecting a calibration short-circuit current when the reference contact is short-circuited, A step of detecting a calibration open-circuit voltage by opening the reference contact under the condition that the temperature at the measurement position and the reference temperature are the same as in the step of detecting the calibration short-circuit current, A step of calculating the current-indicated temperature difference between the temperature measuring junction and the reference junction from the calibration short-circuit current using the current-temperature conversion formula, A step of calculating the voltage-indicated temperature difference between the temperature measuring junction and the reference junction from the calibration open-circuit voltage using a pre-set voltage-temperature conversion formula, A step of calculating a correction coefficient to be multiplied by the temperature difference derived by the current-temperature conversion formula during normal measurement, as the ratio of the voltage-indicated temperature difference to the current-indicated temperature difference, A method for calibrating a temperature measuring device, comprising the following features.

2. The method for calibrating a temperature measuring device according to claim 1, further comprising the step of deriving the temperature of the temperature measuring junction from the current-indicated temperature difference, the reference temperature, and the performance index which is an intrinsic value of the thermocouple.

3. A temperature measuring device calibration device for calibrating a temperature measuring device, which uses a thermocouple having a temperature measuring junction placed at a measurement position and a reference junction held at a reference temperature, detects the short-circuit current flowing through the thermocouple when the reference junction is short-circuited, and calculates the temperature of the temperature measuring junction by deriving the temperature difference between the temperature measuring junction and the reference junction using a preset current-temperature conversion formula, A current-indicated temperature difference calculation unit calculates the current-indicated temperature difference between the temperature measuring junction and the reference junction using the current-temperature conversion formula, based on the calibration short-circuit current detected by short-circuiting the reference junction. A voltage-indicated temperature difference calculation unit calculates the voltage-indicated temperature difference between the temperature measuring junction and the reference junction using a preset voltage-temperature conversion formula, based on the calibration open-circuit voltage detected by opening the reference junction under the condition that the temperature at the measurement position and the reference temperature are the same as when the calibration short-circuit current is detected. A correction coefficient calculation unit calculates a correction coefficient to be multiplied by the temperature difference derived by the current-temperature conversion formula during normal measurement, as the ratio of the voltage-indicated temperature difference to the current-indicated temperature difference, A temperature measuring device calibration device equipped with the following features.

4. A thermocouple having a temperature sensing junction positioned at the measurement location and a reference junction maintained at a reference temperature, A switching circuit that short-circuits or opens the aforementioned reference contacts, inserts a current detector between the reference contacts when short-circuited, and inserts a voltage detector between the reference contacts when open, A temperature measuring device equipped with the following features.

5. A heating circuit that generates heat in response to the input power, A temperature measuring device according to claim 4, wherein the position into which the heat generated by the heating circuit flows is arranged as the measurement position, The switching circuit inserts a current detector between the reference contacts, A current and voltage measuring device equipped with the following features.

6. The current detector comprises a coil that generates a magnetic field due to a short-circuit current when the reference contact is short-circuited, and a magnetic field detector that detects the magnetic field generated by the coil, as described in claim 5.

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