Displacement measurement system, displacement measurement method, and program

Abstract

To provide a displacement measurement system, a displacement measurement method, and a program that can appropriately measure displacement under a cryogenic environment.SOLUTION: A displacement measurement system includes: a displacement detection section having a coil; a temperature detection section measuring temperature of the coil; an oscillation circuit applying an AC voltage to the displacement detection section; a signal processing section performing displacement calculation processing based on the temperature of the coil measured by the temperature detection section; and an amplitude control section controlling amplitude of the AC voltage that is output by the oscillation circuit based on the temperature of the coil measured by the temperature detection section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a displacement measurement system, a displacement measurement method, and a program. [Background technology]

[0002] Eddy current displacement sensors are known as sensors for detecting displacement. For example, Patent Document 1 discloses a displacement sensor including a detection unit including a coil, an oscillation circuit that supplies an AC signal to the detection unit, an external circuit that is connected to the detection unit, and a displacement detection means that detects displacement based on the amount of phase change in the impedance of the detection unit and the external circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-38849 A Summary of the Invention [Problem to be solved by the invention]

[0004] When such a displacement sensor is used in an extremely low-temperature environment of -196°C or below, the output voltage of the displacement sensor increases in response to the displacement of the measurement object, and when the displacement of the measurement object is large, the output voltage exceeds the measurable range, making it impossible to accurately measure the displacement of the measurement object.In addition, when temperature fluctuations are large, a difference occurs between the temperature of the displacement sensor and the temperature of the temperature sensor that measures that temperature, which causes problems when performing temperature correction of the displacement sensor.

[0005] In view of the above-mentioned problems, the present disclosure aims to provide a displacement measurement system, a displacement measurement method, and a program capable of appropriately measuring displacement in an extremely low temperature environment. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objective, the displacement measurement system of the present disclosure comprises a displacement detection unit having a coil, a temperature detection unit that measures the temperature of the coil, an oscillation circuit that applies an AC voltage to the displacement detection unit, a signal processing unit that executes a displacement calculation process based on the temperature of the coil measured by the temperature detection unit, and an amplitude control unit that controls the amplitude of the AC voltage output by the oscillation circuit based on the temperature of the coil measured by the temperature detection unit.

[0007] In order to solve the above-mentioned problems and achieve the objective, the displacement measurement method of the present disclosure includes the steps of acquiring the temperature of the coil of the displacement detection unit, determining the amplitude of the AC voltage to be output from the oscillator circuit based on the acquired coil temperature, outputting the determined AC voltage to the oscillator circuit, acquiring an output signal of the displacement detection unit, and calculating the displacement based on the coil temperature.

[0008] In order to solve the above-mentioned problems and achieve the objective, the program of the present disclosure causes a computer to execute the steps of acquiring the temperature of the coil of the displacement detection unit, determining the amplitude of the AC voltage to be output to the oscillator circuit based on the acquired coil temperature, outputting the determined AC voltage to the oscillator circuit, acquiring an output signal of the displacement detection unit, and calculating the displacement based on the coil temperature. Effect of the Invention

[0009] According to the present invention, it is possible to provide a displacement measurement system, a displacement measurement method, and a program capable of appropriately measuring displacement in an extremely low temperature environment. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing an example configuration of a displacement measuring system according to the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating an example of a configuration of a sensor unit according to the present disclosure. [Diagram 3]FIG. 3 is a flowchart illustrating a displacement measuring method according to the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating a first example of AC voltage amplitude control according to the present disclosure. [Diagram 5] FIG. 5 is a diagram illustrating a second example of AC voltage amplitude control according to the present disclosure. [Figure 6] FIG. 6 is a diagram illustrating an example of a configuration of a sensor unit according to the present disclosure. [Figure 7] FIG. 7 is a diagram showing an example of changes over time in the displacement detection unit temperature and the temperature detection unit temperature according to the present disclosure. [Figure 8] FIG. 8 is a diagram showing another example of the configuration of the sensor unit according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below.

[0012] Fig. 1 is a block diagram showing an example of the configuration of a displacement measurement system according to the present disclosure. Fig. 2 is a diagram showing an example of the configuration of a sensor unit according to the present disclosure. As shown in Fig. 1, a displacement measurement system 100 according to the present disclosure includes a sensor unit 110, an oscillation circuit 120, an amplitude control unit 130, and a signal processing unit 140. The amplitude control unit 130 and the signal processing unit 140 may be configured as hardware using circuit elements, but may also be configured as software by describing the functions of each circuit using a program that causes a computer to execute the program, and causing an arithmetic processing device such as a CPU (Central Processing Unit) to execute the program.

[0013] The sensor unit 110 is disposed facing the object to be measured, and measures the displacement of the object to be measured by detecting the distance from the object to be measured. As shown in FIG. 2, the sensor unit 110 includes a displacement detection unit 111, a temperature detection unit 112, and an outer cylinder 113.

[0014] The displacement detection unit 111 is disposed facing the object to be measured, and detects the distance (gap) from the object to be measured without contacting the object to be measured. The displacement detection unit 111 includes a coil 131 formed of a conductive material such as metal, and the impedance of which changes depending on the displacement of the object to be measured when an AC voltage is applied. The displacement detection unit 111 has a conductor 132 connected to an end of the coil 131, and is connected to the oscillation circuit 120. The coil 131 may be a solenoid coil formed in a spiral shape. The coil 131 may be an air-core coil. An AC signal (AC voltage) applied by the oscillation circuit 120 is applied to the coil 131.

[0015] A high-frequency current flows through coil 131 in response to the AC voltage applied by oscillator circuit 120, generating a high-frequency magnetic field. When an object to be measured is located within this magnetic field, an eddy current flows around the magnetic flux passing through the surface of the object to be measured due to the electromagnetic induction effect of the magnetic field, causing a change in the impedance of coil 131. Since the impedance of coil 131 changes depending on the distance between coil 131 and the object to be measured, the displacement of the object to be measured can be measured by measuring the change in the output voltage of coil 131 due to the change in impedance of coil 131.

[0016] The temperature detection unit 112 measures the temperature of the coil 131 of the displacement detection unit 111. The temperature detection unit 112 is disposed inside the sensor unit 110. The tip of the temperature detection unit 112 may be in contact with the coil 131. The temperature detection unit 112 is a sensor capable of detecting a temperature in a low temperature range of -196°C or lower. The temperature detection unit 112 may use a thermocouple. The thermocouple may be, for example, a Chromel (registered trademark)-Alumel (registered trademark) thermocouple (symbol K of the type of thermocouple defined in JIS C 1602), a Chromel (registered trademark)-Constantan thermocouple (symbol E of the type of thermocouple defined in JIS C 1602), a Nicrosil-Nisil thermocouple (symbol N of the type of thermocouple defined in JIS C 1602), a copper-Constantan thermocouple (symbol T of the type of thermocouple defined in JIS C 1602), or the like.

[0017] The outer cylinder 113 is a container that houses the displacement detection unit 111 and the temperature detection unit 112. The shape of the outer cylinder 113 may be, for example, a hollow cylindrical shape with one end open and a bottom. The material of the outer cylinder 113 may be, for example, a non-conductive material such as resin or ceramic.

[0018] The oscillator circuit 120 applies an AC voltage to the coil 131 of the displacement detection unit 111. The oscillator circuit 120 outputs an AC voltage at a frequency corresponding to the inductance of the coil 131 of the displacement detection unit 111. The oscillator circuit 120 is configured, for example, by an LC oscillator circuit, which is a high-frequency oscillator circuit. The configuration of the oscillator circuit 120 is not particularly limited. The LC oscillator circuit may be configured by a method such as a Hartley type, a Colpitts type, a collector-tuned type, a base-tuned type, or an emitter-tuned type.

[0019] The amplitude control section 130 controls the amplitude of the AC voltage output by the oscillation circuit 120, that is, the voltage value, based on the temperature of the coil 131 measured by the temperature detection section 112. The amplitude control section 130 controls the amplitude of the AC voltage output by the oscillation circuit 120 by continuously increasing it from the low temperature side to the high temperature side in response to the change in temperature of the coil 131. The amplitude control section 130 may, for example, acquire the temperature characteristics of the displacement detection section 111 in advance, store this, and execute the correction process. Also, conversion may be performed using a regression equation using calibration data measured in advance.

[0020] The signal processing unit 140 executes a displacement calculation process based on the output signal of the displacement detection unit 111 and the temperature of the coil 131 measured by the temperature detection unit. The signal processing unit 140 is an arithmetic processing device having a calculation device such as a CPU and storage devices such as a ROM and a RAM. The signal processing unit 140 stores a program, controls the processing of each unit based on the program, and calculates the distance to the measurement object.

[0021] The signal processing unit 140 determines the amplitude of the AC voltage based on the detection result of the temperature detected by the temperature detection unit 112, and controls the amplitude control unit 130 and the oscillation circuit 120 to input the AC voltage of the determined amplitude to the coil 131, thereby acquiring the signal detected by the displacement detection unit 111. The signal processing unit 140 processes the detected signal based on the condition of the input signal and the detection result of the temperature, and calculates the distance to the detection object. The signal processing unit 140 can detect the displacement based on the change in distance.

[0022] Next, the displacement measuring method will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the displacement measuring method according to the present disclosure. As shown in FIG. 3, the displacement measuring method according to the present disclosure is configured by the following five steps. First, the temperature of the coil 131 of the displacement detection unit 111 is acquired (step S100). Next, based on the acquired temperature of the coil 131, the amplitude of the AC voltage to be outputted from the oscillation circuit 120 is determined (step S110). Next, the AC voltage with the determined amplitude is outputted from the oscillation circuit 120 (step S120). Next, the output signal of the displacement detection unit 111 is acquired (step S130). Next, the displacement is calculated based on the temperature of the coil 131 (step S140).

[0023] As a result, the displacement measurement system 100 detects the temperature of the displacement detection unit 111 and adjusts the amplitude of the AC voltage during measurement based on the detected temperature, making it possible to accurately calculate the displacement of the measurement object even in a temperature range where the sensitivity of the output signal to the displacement of the measurement object is high, such as in an extremely low temperature region.

[0024] FIG. 4 is a diagram showing an example of AC voltage amplitude control according to the present disclosure. In FIG. 4, the horizontal axis is the sensor temperature, that is, the temperature of the displacement detection unit 111. Temperatures T1 and T2 are temperatures in the cryogenic temperature region. Here, the cryogenic temperature region is, for example, a temperature below −196° C. For example, T1 is −253° C. and T2 is −196° C. As shown in FIG. 4, the amplitude control unit 130 controls the AC voltage amplitude so that the temperature of the coil 131 increases continuously from the low temperature side to the high temperature side. As shown in FIG. 4, the displacement detection unit 111 has a higher sensor sensitivity as the temperature of the sensor decreases. In particular, in the cryogenic temperature region, the change in the output voltage of the coil 131 with respect to the displacement of the measurement object increases, and the sensor sensitivity increases. When the temperature of the coil 131 decreases, the resistance of the coil 131 decreases, so that the impedance of the coil 131 decreases, which is considered to be an effect of making it easier for an AC current to flow through the coil 131.

[0025] The amplitude control section 130 according to the present embodiment continuously changes the amplitude with respect to the sensor temperature as shown by the AC voltage amplitude. Specifically, the amplitude control section 130 sets the amplitude of the AC voltage output by the oscillation circuit 120 in the cryogenic temperature region to be smaller than that in the normal temperature region, thereby reducing the amplitude of the output voltage of the coil 131 in the cryogenic temperature region by reducing the AC voltage applied to the coil 131 compared to that in the normal temperature region. That is, the amplitude control section 130 controls the amplitude of the AC voltage output by the oscillation circuit 120 to be smaller on the low temperature side so that the amplitude of the output signal of the displacement detection section 111 is included in the measurable range. Therefore, it is possible to keep the amplitude of the output voltage of the coil 131 in the cryogenic temperature region within the measurable range of the output voltage of the signal processing section 140. Therefore, by the amplitude control section 130 controlling the amplitude of the AC voltage output by the oscillation circuit 120 as described above, it is possible to appropriately measure the displacement of the measurement object even in the cryogenic temperature region. For example, by correcting the output signal based on temperature, it is possible to measure the displacement even when a temperature change occurs that makes it impossible to measure the displacement because the amplitude of the output signal from the displacement detection unit 111 exceeds the measurable range of the output voltage of the signal processing unit 140. In addition, in order to deal with an extremely low temperature range, it is possible to set the sensitivity low and suppress a decrease in the measurement accuracy of the displacement in a temperature range with low sensitivity, for example, at temperatures higher than T2.

[0026] FIG. 5 is a diagram showing another example of AC voltage amplitude control according to the present disclosure. As shown in FIG. 5, the amplitude control unit 130 may divide the temperature of the coil 131 into a plurality of ranges, and set the amplitude of the AC voltage output by the oscillation circuit 120 to a specific amplitude when the temperature of the coil 131 is included in a specific range. In FIG. 5, the temperature range of the sensor temperature from temperature T1 to T2 is divided into two. In this case, the amplitude of the AC voltage is controlled to be smaller in the temperature range of the lower temperature side of the divided temperature range than in the temperature range of the higher temperature side. In addition, the amplitude control unit 130 controls the amplitude of the AC voltage to be larger than in the temperature range of the lower temperature side when the sensor temperature is included in the temperature range of the temperature range of the sensor temperature from temperature T1 to T2 divided into two. Here, it is preferable to set the amplitude of the AC voltage so that the amplitude of the output signal of the displacement detection unit 111 is included in the measurable range. The temperature range in which the amplitude control unit 130 controls the amplitude of the AC voltage by changing it stepwise may be, for example, a temperature range from −253° C. (20 K) to −196° C. (77 K), in which the change in sensor sensitivity is particularly large. The number of divisions into which the temperature of the coil 131 is divided is not limited to two, and may be any other number of divisions.

[0027] This allows the AC voltage output by the oscillator circuit 120 to be controlled at low cost using a simple control method. Therefore, by suppressing the generation of an output signal that exceeds the measurable range of the signal processor 140 even in an extremely low temperature region, it becomes possible to measure the displacement of the measurement target.

[0028] Here, it is preferable that the amplitude control section 130 sets the rate of change of the amplitude at −253° C. relative to the amplitude at 27° C. to be 1.6 times or more the rate of change of the amplitude at −196° C. relative to the amplitude at 27° C. This makes it possible to detect displacement with high sensitivity in the cryogenic temperature region while making it possible to measure displacement in a higher temperature region than in the cryogenic temperature region.

[0029] Fig. 6 is a diagram showing an example of the configuration of a sensor unit according to the present disclosure. A sensor unit 110a of the displacement measurement system shown in Fig. 6 includes a displacement detection unit 111, a temperature detection unit 112, an outer cylinder 113, and a vacuum layer unit 114. The displacement detection unit 111 and the temperature detection unit 112 are the same as the displacement detection unit 111 and the temperature detection unit 112 of the displacement measurement system 100 according to the first embodiment, and therefore a description thereof will be omitted.

[0030] The vacuum layer 114 is provided on the outer cylinder 113 that covers the displacement detection unit 111 or around the displacement detection unit 111 , and suppresses the inflow of heat into the displacement detection unit 111 .

[0031] The vacuum layer 114 is a heat insulating layer in which the internal air pressure is kept extremely low. The degree of vacuum in the vacuum layer 114 is limited to 10°C due to the constraint of the distance from the tip of the outer cylinder 113 to the tip of the coil 131 of the displacement detection unit 111. -2 The lower the degree of vacuum in the vacuum layer 114, the lower the thermal conductivity, which is preferable. However, due to manufacturing constraints, the degree of vacuum is preferably set to 10 -4 The degree of vacuum may be equal to or higher than 1 Pa. This suppresses the inflow of heat into the displacement detection unit 111, thereby reducing temperature fluctuations in the displacement detection unit 111. Therefore, even in an environment with severe temperature fluctuations, such as an extremely low temperature region, the output signal of the displacement detection unit 111 can be stabilized against temperature fluctuations in the surrounding environment.

[0032] FIG. 7 is a diagram showing an example of the change over time of the displacement detection unit temperature and the temperature detection unit temperature. As shown in FIG. 7, in an environment where the temperature change over time is large, such as an extremely low temperature region, it is assumed that a time delay occurs between the temperature change of the displacement detection unit temperature and the temperature detection unit temperature. In this case, a temperature difference such as the temperature difference ΔT1 shown in FIG. 7 occurs between the displacement detection unit temperature and the temperature detection unit temperature. In an extremely low temperature region where the change in sensor sensitivity is rapid, a slight temperature difference may cause a large deviation in the displacement obtained from the output voltage of the displacement detection unit 111. The sensor unit 110a is provided with a vacuum layer portion 114, and by reducing the temperature change of the displacement detection unit 111, the temperature difference between the displacement detection unit 111 and the temperature detection unit 112 can be reduced. Therefore, it is possible to appropriately measure the displacement of the measurement object in an extremely low temperature region.

[0033] Fig. 8 is a diagram showing another example of the configuration of a sensor unit according to the present disclosure. The sensor unit 110b of the displacement measurement system shown in Fig. 8 has a displacement detection unit 111, a temperature detection unit 112, an outer cylinder 113, and a heat transfer unit 115. The displacement detection unit 111 and the temperature detection unit 112 are the same as the displacement detection unit 111 and the temperature detection unit 112 of the sensor unit 110, and therefore a description thereof will be omitted.

[0034] The heat transfer unit 115 is provided between the displacement detection unit 111 and the temperature detection unit 112, and promotes the transfer of heat between the displacement detection unit 111 and the temperature detection unit 112. The heat transfer unit 115 may be configured to circulate a fluid such as liquid hydrogen, liquid helium, or neon between the displacement detection unit 111 and the temperature detection unit 112. This makes it possible to generate forced convection heat transfer between the fluid and the displacement detection unit 111 and the temperature detection unit 112, thereby reducing the temperature difference between the displacement detection unit 111 and the temperature detection unit 112.

[0035] Therefore, in the displacement calculation process in the signal processing unit 140, the temperature measurement value of the temperature detection unit 112 may be regarded as the same as the temperature of the displacement detection unit 111, and it becomes possible to calculate the displacement of the measurement object by accurately reflecting the temperature of the displacement detection unit 111. Therefore, it becomes possible to accurately measure the displacement of the measurement object even in an environment with large temperature fluctuations such as an extremely low temperature region.

[0036] (Composition and Effects) The displacement measurement system 100 according to the present disclosure includes a displacement detection unit 111 having a coil 131, a temperature detection unit 112 that measures the temperature of the coil 131, an oscillation circuit 120 that applies an AC voltage to the displacement detection unit 111, a signal processing unit 140 that executes a displacement calculation process based on the temperature of the coil 131 measured by the temperature detection unit 112, and an amplitude control unit 130 that controls the amplitude of the AC voltage output by the oscillation circuit 120 based on the temperature of the coil 131 measured by the temperature detection unit 112.

[0037] According to this configuration, the influence of temperature-induced resistance changes in coil 131 on the sensor sensitivity of the output signal relative to the displacement of displacement detection unit 111 can be reflected in the amplitude of the AC voltage output by oscillation circuit 120. Therefore, it is possible to calculate the displacement of the measurement object by taking into account the temperature-induced change in the output signal of displacement detection unit 111.

[0038] The signal processing unit 140 of the displacement measuring system 100 according to the present disclosure further executes a displacement calculation process based on the output signal of the displacement detection unit 111 .

[0039] According to this configuration, the influence of temperature-induced resistance changes in coil 131 on the sensor sensitivity of the output signal relative to the displacement of displacement detection unit 111 can be reflected in the amplitude of the AC voltage output by oscillation circuit 120. Therefore, it is possible to calculate the displacement of the measurement object by taking into account the temperature-induced change in the output signal of displacement detection unit 111.

[0040] It is preferable that the amplitude control unit 130 of the displacement measuring system 100 according to the present disclosure controls the amplitude of the AC voltage output by the oscillator circuit 120 by changing it so that it increases continuously from the low temperature side to the high temperature side in response to the change in temperature of the coil 131.

[0041] According to this configuration, even in a temperature range where the sensor sensitivity of the output signal of the displacement detection unit 111 to the displacement of the measurement object becomes high, such as in a cryogenic temperature region, it is possible to prevent the amplitude of the output signal of the displacement detection unit 111 from exceeding the measurable range. Therefore, it is possible to accurately calculate the displacement of the measurement object even in a cryogenic temperature environment.

[0042] It is preferable that the amplitude control unit 130 of the displacement measurement system 100 according to the present disclosure divides the temperature of the coil 131 into a plurality of intervals, and when the temperature of the coil 131 is included in a specific interval, controls the oscillator circuit 120 to output a specific AC voltage amplitude, and controls the amplitude of the AC voltage to be increased stepwise from the low temperature side to the high temperature side.

[0043] According to this configuration, it is possible to control the amplitude of the AC voltage output by the oscillation circuit 120 at low cost using a simple control method. Also, even in a temperature range where the sensitivity of the output signal of the displacement detection unit 111 to the displacement of the measurement object becomes high, such as in a cryogenic temperature region, it is possible to prevent the amplitude of the output signal of the displacement detection unit 111 from exceeding the measurable range. Therefore, it is possible to accurately calculate the displacement of the measurement object even in a cryogenic temperature environment.

[0044] It is preferable to provide an outer cylinder 113 which covers the displacement detection unit 111 , or a vacuum layer 114 which is provided around the displacement detection unit 111 and prevents the inflow of heat into the displacement detection unit 111 .

[0045] According to this configuration, it is possible to suppress temperature fluctuations in the displacement detection unit 111, and therefore to mitigate changes in sensitivity of the output signal to the displacement of the displacement detection unit 111 due to temperature. Therefore, even in a temperature range where the sensitivity of the output signal of the displacement detection unit 111 to the displacement of the measurement object becomes high, such as in an extremely low temperature region, it is possible to accurately calculate the displacement of the measurement object.

[0046] It is preferable to include a heat transfer section 115 provided between the displacement detection section 111 and the temperature detection section 112 to promote the transfer of heat between the displacement detection section 111 and the temperature detection section 112.

[0047] This configuration makes it possible to suppress the temperature difference between the displacement detection unit 111 and the temperature detection unit 112. Therefore, even if there is a large temperature fluctuation over time, such as in displacement measurement in an extremely low temperature region, it becomes possible to accurately calculate the displacement of the measurement object.

[0048] Here, it is preferable that the amplitude control section 130 sets the rate of change of the amplitude at −253° C. relative to the amplitude at 27° C. to be 1.6 times or more the rate of change of the amplitude at −196° C. relative to the amplitude at 27° C. This makes it possible to detect displacement with high sensitivity in the cryogenic temperature region while making it possible to measure displacement in a higher temperature region than in the cryogenic temperature region.

[0049] The displacement measurement method according to the present disclosure includes the steps of acquiring the temperature of the coil 131 in the displacement detection unit 111, determining the amplitude of the AC voltage to be output by the oscillation circuit 120 based on the acquired temperature of the coil 131, causing the oscillation circuit 120 to output the AC voltage with the determined amplitude, acquiring an output signal from the displacement detection unit 111, and calculating the displacement based on the temperature of the coil 131.

[0050] According to this configuration, the influence on the sensor sensitivity of the output signal for the displacement of the displacement detection unit 111 due to the resistance change of the coil 131 caused by temperature can be reflected in the amplitude of the AC voltage output by the oscillation circuit 120. Therefore, it becomes possible to calculate the displacement of the measurement object by taking into account the change in the output signal of the displacement detection unit 111 caused by temperature.

[0051] The program of the present disclosure causes a computer to execute the steps of acquiring the temperature of the coil 131 possessed by the displacement detection unit 111, determining the amplitude of the AC voltage to be output by the oscillation circuit 120 based on the acquired temperature of the coil 131, outputting the AC voltage with the determined amplitude to the oscillation circuit 120, acquiring an output signal from the displacement detection unit 111, and calculating the displacement based on the temperature of the coil 131.

[0052] According to this configuration, the influence on the sensor sensitivity of the output signal for the displacement of the displacement detection unit 111 due to the resistance change of the coil 131 caused by temperature can be reflected in the amplitude of the AC voltage output by the oscillation circuit 120. Therefore, it becomes possible to calculate the displacement of the measurement object by taking into account the change in the output signal of the displacement detection unit 111 caused by temperature.

[0053] Although the embodiment of the present invention has been described above, the embodiment is not limited to the contents of this embodiment. The above-mentioned components include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-mentioned components can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the gist of the above-mentioned embodiment. [Explanation of symbols]

[0054] 100 Displacement measurement system 110, 110a, 110b Sensor section 111 Displacement detection unit 112 Temperature detection unit 113 Outer cylinder 114 Vacuum layer section 115 Heat transfer section 120 Oscillator Circuit 130 Amplitude control section 140 Signal Processing Section

Claims

1. A displacement detection unit having a coil; A temperature detection unit that measures the temperature of the coil; an oscillator circuit that applies an AC voltage having a frequency corresponding to the inductance of the coil to the displacement detection unit; a signal processing unit that executes a displacement calculation process based on the temperature of the coil measured by the temperature detection unit; an amplitude control unit that controls the amplitude of the AC voltage output by the oscillation circuit based on the temperature of the coil measured by the temperature detection unit; The amplitude control section is configured such that a rate of change of the amplitude at −253° C. relative to the amplitude at 27° C. is 1.6 times or more of a rate of change of the amplitude at −196° C. relative to the amplitude at 27° C. Displacement measurement system.

2. The signal processing unit further executes a displacement calculation process based on the output signal of the displacement detection unit. The displacement measurement system according to claim 1 .

3. The amplitude control unit controls the amplitude of the AC voltage output by the oscillation circuit by continuously increasing the amplitude from a low temperature side to a high temperature side in response to the temperature of the coil. The displacement measuring system according to claim 1 or 2.

4. The amplitude control unit divides the temperature of the coil into a plurality of sections, and when the temperature of the coil is included in a specific section, controls the oscillation circuit to output a specific AC voltage amplitude, and controls the amplitude of the AC voltage to be increased stepwise from the low temperature side to the high temperature side. The displacement measuring system according to claim 1 or 2.

5. An outer cylinder covering the displacement detection unit, or a vacuum layer portion provided around the displacement detection unit to prevent heat from flowing into the displacement detection unit. The displacement measuring system according to any one of claims 1 to 4.

6. a heat transfer section provided between the displacement detection section and the temperature detection section, and promoting transfer of heat between the displacement detection section and the temperature detection section. The displacement measuring system according to any one of claims 1 to 5.

7. acquiring a temperature of a coil of a displacement detection unit; determining an amplitude of an AC voltage to be output from the oscillator circuit based on the obtained coil temperature; A step of outputting an AC voltage having a determined amplitude and a frequency corresponding to the inductance of the coil to an oscillator circuit; acquiring an output signal of a displacement detection unit; and calculating the displacement based on the temperature of the coil; In the step of determining the amplitude, a rate of change of the amplitude at −253° C. relative to the amplitude at 27° C. is determined to be 1.6 times or more of a rate of change of the amplitude at −196° C. relative to the amplitude at 27° C. Displacement measurement method.

8. acquiring a temperature of a coil of a displacement detection unit; determining an amplitude of an AC voltage to be output from the oscillator circuit based on the obtained coil temperature; A step of outputting an AC voltage having a determined amplitude and a frequency corresponding to the inductance of the coil to an oscillator circuit; acquiring an output signal of a displacement detection unit; calculating the displacement based on the temperature of the coil; In the step of determining the amplitude, a rate of change of the amplitude at −253° C. relative to the amplitude at 27° C. is determined to be 1.6 times or more of a rate of change of the amplitude at −196° C. relative to the amplitude at 27° C. A program that causes a computer to execute the following.

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