Displacement measurement system and processing method of the displacement measurement system

Abstract

To enable high-precision detection of the position of the second transmission line coupler relative to the first transmission line coupler. [Solution] The displacement measurement system includes a first transmission line coupler to which a first signal including a first frequency component is input, a second transmission line coupler that is movable relative to the first transmission line coupler, a phase difference detection unit that detects the phase difference between the signal of the first frequency component output from the second transmission line coupler and the second signal of the first frequency, and a counting unit that changes the value of an internal counter each time the phase difference rotates 360 degrees.

Description

Technical Field

[0001] The present disclosure relates to a displacement measurement system and a processing method for a displacement measurement system.

Background Art

[0002] In recent years, systems for measuring the displacement of a detector that moves non-contact on a transmission line have been researched and developed. For example, Non-Patent Document 1 discloses a system that generates a standing wave on a transmission line, acquires the amplitude level and phase of the standing wave with a detector, and measures the displacement of the detector on the transmission line.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the system described in Non-Patent Document 1, the amplitude level of the standing wave on the transmission line forms a curve and has different slopes depending on the position of the transmission line, so the detection accuracy is different. In particular, near the peak of the curve, the slope is gentle and the change in the amplitude level is small, so the detection accuracy is rough.

[0005] An object of the present disclosure is to enable highly accurate detection of the position of a second transmission line coupler with respect to a first transmission line coupler.

Means for Solving the Problems

[0006] The displacement measurement system includes a first transmission line coupler to which a first signal containing a first frequency component is input, a second transmission line coupler that is movable relative to the first transmission line coupler, a phase difference detection unit that detects the phase difference between the signal of the first frequency component output from the second transmission line coupler and the second signal of the first frequency, and a counting unit that changes the value of an internal counter each time the phase difference rotates 360 degrees. [Effects of the Invention]

[0007] According to this disclosure, the position of the second transmission line coupler relative to the first transmission line coupler can be detected with high precision. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example configuration of a displacement measurement system according to the first embodiment. [Figure 2] This figure shows examples of the configuration of the phase difference detection unit according to the first and third embodiments. [Figure 3] This figure shows the relationship between the displacement and phase difference of the transmission line coupler according to the first and second embodiments. [Figure 4] This figure shows an example configuration of a displacement measurement system according to the second embodiment. [Figure 5] This figure shows the relationship between transmitted and received data waveforms and time according to the second embodiment. [Figure 6] This figure shows an example configuration of a displacement measurement system according to the third embodiment. [Figure 7] This figure shows the relationship between the displacement and phase difference of the transmission line coupler according to the third embodiment. [Figure 8] This figure shows an example configuration of a displacement measurement system according to the fourth embodiment. [Figure 9] This figure shows the relationship between the displacement and phase difference of the transmission line coupler according to the fourth embodiment. [Figure 10] This figure shows an example configuration of a displacement measurement system according to the fifth embodiment. [Figure 11]It is a diagram showing the relationship between the displacement and the phase difference of the transmission line coupler according to the fifth embodiment.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, this embodiment will be described with reference to the drawings. For the sake of simplicity of explanation, the attenuation amount of the signal is not considered in this specification.

[0010] (First Embodiment) FIG. 1 shows a configuration example of a displacement measurement system 100 according to the first embodiment. The displacement measurement system 100 includes an AC signal source 101, a first cable 102, a second cable 103, a first transmission line coupler 104, a second transmission line coupler 105, a phase difference detection unit 106, a counting unit 107, and a resistor 108. Hereinafter, the processing method of the displacement measurement system 100 will be described.

[0011] The AC signal source 101 outputs a sine wave signal of an arbitrary frequency to the first transmission line coupler 104 via the first cable 102.

[0012] Also, the AC signal source 101 outputs a sine wave signal of an arbitrary frequency to the phase difference detection unit 106 via the second cable 103.

[0013] The first transmission line coupler 104 is a linear transmission line. A sine wave signal from the AC signal source 101 is input from one end of the line, and the other end is terminated in impedance matching with a resistor 108 equal to the characteristic impedance of the transmission line.

[0014] The second transmission line coupler 105 is a linear transmission line, which is shorter than the first transmission line coupler 104 and moves horizontally while maintaining a certain distance from the first transmission line coupler 104.

[0015] The first transmission line coupler 104 and the second transmission line coupler 105 function as a directional coupler. At the end of the second transmission line coupler 105, the side in the direction in which the traveling wave of the first transmission line coupler 105 advances is called the separation end, and the end opposite to the separation end is called the coupling end.

[0016] Here, let the distance from the signal input end of the first transmission line coupler 104 to the coupling end of the second transmission line coupler 105 be distance x, the length of the second transmission line coupler 105 be distance y, and the distance from the coupling end of the second transmission line coupler 105 to an arbitrary position be distance z.

[0017] If the signal S1 input to the signal input end of the first transmission line coupler 104 is expressed by Equation 1, the signal is coupled to the second transmission line coupler 105 from distance x to distance x + y, and the signal S2 at the right end transmitted to the second transmission line coupler 105 is expressed by Equation 2. The coefficient k indicates the coupling degree per unit length. The wavelength λ indicates the wavelength of the sine wave signal generated by the AC signal source 101. Due to the line length difference between the first cable 102 and the second cable 103, a phase difference occurs in the phase of the sine wave signal input to the first transmission line coupler 104 and the phase difference detection unit 106. Let this phase difference be θ0.

[0018]

Equation

[0019] The third term inside the parentheses in Equation 2 indicates the amount of phase change when the traveling wave is transmitted on the first transmission line coupler 104, and the fourth term indicates the amount of phase change when the traveling wave is transmitted on the second transmission line coupler 105. Solving Equation 2, the signal S2 is expressed by Equation 3.

[0020]

Equation

[0021] The phase difference detection unit 106 detects and outputs the phase difference Δθ between the sine wave signal S1 generated by the AC signal source 101 and the signal S2 at the separation end of the second transmission line coupler 105. The phase difference Δθ is expressed by Equation 4.

[0022]

number

[0023] In other words, the phase difference Δθ output by the phase difference detection unit 106 allows for the measurement of the displacement x+y of the second transmission line coupler 105 relative to the first transmission line coupler 104.

[0024] The counting unit 107, with an initial value of 0 for the internal counter and the initial output of the phase difference detection unit 106 as the initial phase difference, subtracts 1 from the internal counter when the second transmission line coupler 105 moves to the signal input end side of the first transmission line coupler 104 and the phase difference rotates 360 degrees back to the initial phase difference. If the second transmission line coupler 105 moves to the resistor termination side of the first transmission line coupler 104 and the phase difference rotates 360 degrees back to the initial phase difference, adds 1 to the internal counter.

[0025] Furthermore, the displacement measurement system 100 inputs the output of the phase difference detection unit 106 and the output of the counting unit 107 to a displacement calculation unit (not shown) that calculates the displacement x+y of the second transmission line coupler 105 relative to the first transmission line coupler 104.

[0026] Figure 2 shows an example of the configuration of the phase difference detection unit 106 according to this embodiment. The phase difference detection unit 106 includes a 90-degree phase shifter 201, multipliers 202 and 203, low-pass filters 204 and 205, and a polar coordinate transformation unit 206. The multiplier 202 multiplies signal S1 and signal S2 and outputs an output signal. The output signal of the multiplier 202 is expressed by Equation 5.

[0027]

number

[0028] When the output signal of the multiplier 202 is input to the low-pass filter 204, only the second term, which is the low-harmonic component of Equation 5, passes through the low-pass filter 204, and the low-pass filter 204 outputs the signal represented by Equation 6.

[0029]

number

[0030] The 90-degree phase shifter 201 delays the phase of signal S1 by 90 degrees and outputs the resulting signal S3. Signal S3 is represented by Equation 7.

[0031]

number

[0032] The multiplier 203 multiplies signal S3 and signal S2 and outputs an output signal. The output signal of the multiplier 203 is expressed by Equation 8.

[0033]

number

[0034] When the output signal of the multiplier 203 is input to the low-pass filter 205, only the second term, which is the low-harmonic component of Equation 8, passes through the low-pass filter 205, and the output signal of the low-pass filter 205 is represented by Equation 9.

[0035]

number

[0036] The polar coordinate conversion unit 206 converts the Cartesian coordinates obtained by equations 6 and 9 into polar coordinates and outputs the phase difference Δθ shown in equation 4. That is, the polar coordinate conversion unit 206 converts the output signals of the low-pass filter 204 and the low-pass filter 205 into polar coordinates and outputs the phase difference Δθ from equation 4 to the counting unit 107.

[0037] Figure 3 shows the relationship between the displacement of the transmission line coupler and the phase difference Δθ according to this embodiment. The horizontal axis represents the position of the second transmission line coupler 105 when the center of the first transmission line coupler 104 is set to 0 mm, and the vertical axis represents the phase difference Δθ output by the phase difference detection unit 106. For example, there are two positions of the second transmission line coupler 105 where the phase difference Δθ = 0, located around -19 mm and +13 mm. However, the output values ​​of the counting unit 107 are -1 and +1, respectively. Even with the same phase difference Δθ, the position of the second transmission line coupler 105 can be identified from the output value of the counting unit 107.

[0038] Here, we have described the signal S2 output at the disconnected end of the second transmission line coupler 105, but the signal S2 output at the disconnected end is based on the premise that the coupled end of the second transmission line coupler 105 is terminated with a termination resistor (not shown).

[0039] On the other hand, even if one end of the second transmission line coupler 105 is not terminated and the signal is detected only by capacitive coupling with the first transmission line coupler 104, a similar signal can be obtained, so the second transmission line coupler 105 may be a capacitively coupled coupler.

[0040] As described above, with this embodiment, the position of the second transmission line coupler 105 relative to the first transmission line coupler 104 can be calculated using the output signal of the phase difference detection unit 106 and the output signal of the counting unit 107.

[0041] Although it is stated that the counting unit 107 updates its internal counter when the phase difference rotates 360 degrees from the initial phase difference detected by the phase difference detection unit 106 and returns to the initial phase difference, the method is not limited to this; for example, the counter may be updated when a predetermined phase difference is reached. Specifically, the counter is updated when it reaches 180 degrees, and the phase difference is rotated 360 degrees. A phase difference obtained by adding -180 degrees to the phase difference output from the phase difference detection unit is detected, and the phase difference is updated when the phase difference becomes 180 degrees again.

[0042] (Second Embodiment) Figure 4 shows an example configuration of a displacement measurement system 400 according to the second embodiment. In addition to the configuration of the displacement measurement system 100 in Figure 1, the displacement measurement system 400 includes a data signal source 401, an adder 402, a third cable 403, a bandpass filter 404, a comparator 405, and a constant voltage source 406.

[0043] The AC signal source 101 outputs a sine wave signal S1 to the adder 402 via the first cable 102.

[0044] The data signal source 401 generates and outputs an arbitrary digital data signal S4. The frequency of the signal S1 output by the AC signal source 101 is set to be sufficiently higher than the frequency of the signal S4 generated by the data signal source 401.

[0045] The adder 402 adds signal S1 and signal S4 generated by data signal source 401 and outputs the result.

[0046] The adder 402 outputs the added signal to the first transmission line coupler 104 via the third cable 403.

[0047] The sum of the lengths of the first cable 102 and the third cable 403 is equal to the length of the second cable 103. The phases of the sinusoidal signal S1 input to the first transmission line coupler 104 and the phase difference detection unit 106 are equal to each other.

[0048] If the signal input to the signal input terminal of the first transmission line coupler 104 is denoted by Equation 1, then this signal is coupled to the second transmission line coupler 105 from distance x to distance x+y, and the leftmost signal S5 transmitted to the second transmission line coupler 105 is represented by Equation 10.

[0049]

number

[0050] The third term in parentheses in Equation 10 represents the phase change when the traveling wave is transmitted over the first transmission line coupler 104, and the fourth term represents the phase change when the traveling wave is transmitted over the second transmission line coupler 105. Solving Equation 10, the signal S5 is expressed in Equation 11.

[0051]

number

[0052] From Equation 11, it can be seen that when the frequency of signal S1 is N / 2y (N: a natural number), the amplitude of signal S5 becomes 0. In other words, by setting the frequency of signal S4 to N / 2y, only the signal transmitted from the data signal source 401 can be acquired at the coupling end of the second transmission line coupler 105.

[0053] The comparator 405 outputs a signal corresponding to a logical value of 1 if the signal transmitted from the coupling terminal of the second transmission line coupler 105 is higher than the voltage level output by the constant voltage source 406, and outputs a signal corresponding to a logical value of 0 if the signal transmitted from the coupling terminal of the second transmission line coupler 105 is lower than the voltage level output by the constant voltage source 406.

[0054] The bandpass filter 404 allows only the frequency component of signal S1 to pass through the signal output from the isolated end of the second transmission line coupler 105.

[0055] The phase difference detection unit 106 receives the signal S1 output by the AC signal source 101 via the second cable 103 and the signal output by the bandpass filter 404, and performs the same processing as in the first embodiment (Figure 2).

[0056] Furthermore, the displacement measurement system 100 inputs the output of the phase difference detection unit 106 and the output of the counting unit 107 to a displacement calculation unit (not shown) that calculates the displacement x+y of the second transmission line coupler 105 relative to the first transmission line coupler 104.

[0057] The relationship between the displacement and phase difference of the transmission line coupler according to this embodiment is the same as in the first embodiment (Figure 3).

[0058] Figure 5 shows the relationship between the transmitted and received data waveforms and time according to this embodiment. In Figure 5(a), the horizontal axis represents time, and the vertical axis represents the output voltage of the data signal source 401. In Figure 5(b), the horizontal axis represents time, and the vertical axis represents the output voltage of the comparator 405. Comparing the two waveforms in Figure 5(a) and Figure 5(b), it can be seen that the output voltage of the data signal source 401 is delayed before being output from the comparator 405.

[0059] As described above, in this embodiment, the position of the second transmission line coupler 105 relative to the first transmission line coupler 104 can be calculated using the output of the phase difference detection unit 106 and the output of the counting unit 107, similar to the first embodiment. Furthermore, the output signal of the data signal source 401 can be output from the comparator 405.

[0060] In the first and second embodiments, a first signal including a first frequency component is input to the first transmission line coupler 104. The second transmission line coupler 105 is movable relative to the first transmission line coupler 104.

[0061] The phase difference detection unit 106 detects the phase difference between the signal of the first frequency component output from the second transmission line coupler 105 and the second signal of the first frequency. The counting unit 107 changes the value of its internal counter each time the phase difference detected by the phase difference detection unit 106 rotates 360 degrees.

[0062] Furthermore, the displacement measurement system may be provided with means for determining the position of the second transmission line coupler 105 relative to the first transmission line coupler 104 from the phase difference detected by the phase difference detection unit 106 and the value of the internal counter in the counting unit 107.

[0063] In Figure 1, the first signal is a signal of the first frequency, and the phase difference detection unit 106 detects the phase difference between the signal output from the second transmission line coupler 105 and the second signal. The AC signal source 101 outputs the first signal and the second signal. The phase difference detection unit 106 detects the phase difference between the signal output from one end of the second transmission line coupler 105 and the second signal, and the other end of the second transmission line coupler 105 is terminated with matching connections. The first signal and the second signal are sinusoidal signals.

[0064] In Figure 4, the bandpass filter 404 outputs the signal of the first frequency component of the signal output from one end of the second transmission line coupler 105. The phase difference detection unit 106 detects the phase difference between the signal output from the bandpass filter 404 and the second signal. The adder 402 adds the second signal and the third signal and outputs the first signal to the first transmission line coupler 104. The frequency of the first signal is higher than the frequency of the third signal. The AC signal source 101 outputs the second signal to the phase difference detection unit 106 and the adder 402. The comparator 405 compares the signal output from the other end of the second transmission line coupler 105 with a threshold. The output signal of the comparator 405 is the third signal with a delay. The third signal is a digital data signal. The second signal is a sine wave signal.

[0065] The first transmission line coupler 104 and the second transmission line coupler 105 are both straight in shape, and the first transmission line coupler 104 is longer than the second transmission line coupler 105. The second transmission line coupler 105 is movable horizontally while maintaining a constant distance from the first transmission line coupler 104.

[0066] The first transmission line coupler 104 has the first signal input at one end and the other end is matched and terminated. The first transmission line coupler 104 and the second transmission line coupler 105 function as a directional coupler. The second transmission line coupler 105 may also be capacitively coupled to the first transmission line coupler 104 and function as a capacitively coupled coupler.

[0067] In Figure 2, the phase difference detection unit 106 detects the phase difference by quadrature demodulating the two input signals S1 and S2 and converting the quadrature demodulated signals into polar coordinates.

[0068] The counting unit 107 stores the initial output value of the phase difference detection unit 106 as the initial phase difference, sets the initial value of the internal counter to 0, subtracts 1 from the internal counter when the second transmission line coupler 105 moves to one end of the first transmission line coupler 104 and the phase difference rotates 360 degrees, and adds 1 to the internal counter when the second transmission line coupler 105 moves to the other end of the first transmission line coupler 104 and the phase difference rotates 360 degrees.

[0069] (Third embodiment) Figure 6 shows an example configuration of a displacement measurement system 600 according to a third embodiment. In addition to the configuration of the displacement measurement system 100 in Figure 1, the displacement measurement system 600 includes a second AC signal source 601, a third cable 602, a fourth cable 603, bandpass filters 604 and 605, a phase difference detection unit 606, and a difference unit 607.

[0070] Note that the counting unit 107 in Figure 1 is unnecessary and has been removed from the configuration. In this embodiment, the AC signal source 101 is referred to as the first AC signal source 101. The frequencies of the sine wave signals generated by the first AC signal source 101 and the second AC signal source 601 are assumed to be different.

[0071] The second AC signal source 601 outputs a sine wave signal to the first transmission line coupler 104 via the third cable 602. The second AC signal source 601 also outputs a sine wave signal to the phase difference detection unit 606 via the fourth cable 603.

[0072] The bandpass filter 604 allows only the frequency components of the sine wave signal generated by the first AC signal source 101 to pass through the signal output from the isolated end of the second transmission line coupler 105.

[0073] The bandpass filter 605 allows only the frequency component of the sine wave signal generated by the second AC signal source 601 to pass through the signal output from the isolated end of the second transmission line coupler 105.

[0074] The phase difference detection unit 106 receives the sinusoidal signal S1 output by the first AC signal source 101 via the second cable 103 and the signal output by the bandpass filter 604, and performs the same processing as in the first embodiment (Figure 2).

[0075] The phase difference detection unit 606 receives the sinusoidal signal output by the second AC signal source 601 via the fourth cable 603 and the signal output by the bandpass filter 605, and performs the same processing as in Figure 2. The phase difference detection unit 606 has the same configuration as the phase difference detection unit 106 in Figure 2.

[0076] The phase difference detection unit 606 detects and outputs the phase difference between the sinusoidal signal generated by the second AC signal source 601 and the signal that has passed through the bandpass filter 605 from the separated end of the second transmission line coupler 104.

[0077] The principle by which the displacement of the second transmission line coupler 105 relative to the first transmission line coupler 104 can be measured using the phase difference Δθ output by the phase difference detection units 106 and 606 is the same as in the first embodiment.

[0078] The difference unit 607 outputs the difference between the phase difference output by the phase difference detection unit 106 and the phase difference output by the phase difference detection unit 606.

[0079] Furthermore, in the displacement measurement system 600, the output of the difference unit 607 is input to a displacement calculation unit (not shown) that calculates the displacement, and the displacement x+y of the second transmission line coupler 105 relative to the first transmission line coupler 104 is calculated.

[0080] Figure 7 shows the relationship between the displacement and phase difference of the transmission line coupler according to this embodiment. In Figure 7(a), the horizontal axis represents the position of the second transmission line coupler 105 when the center of the first transmission line coupler 104 is set to 0 mm, and the vertical axis represents the phase difference output by the phase difference detection units 106 and 606. The frequency of the first AC signal source 101 is 5 GHz, and the frequency of the second AC signal source 601 is 6 GHz.

[0081] Figure 7(b) shows the position of the second transmission line coupler 105 on the horizontal axis, with the center of the first transmission line coupler 104 set to 0 mm, and the difference in the outputs of the two phase difference detection units 106 and 606 on the vertical axis. From Figure 7(b), it can be seen that the difference in the outputs of the two phase difference detection units 106 and 606 becomes an eigenvalue depending on the position of the second transmission line coupler 105.

[0082] As described above, with this embodiment, the absolute position of the second transmission line coupler 105 can be calculated by the difference between the outputs of the two phase difference detection units 106 and 606.

[0083] In this embodiment as well, the second transmission line coupler 105 may be a capacitive coupler, similar to the first embodiment.

[0084] As described above, the first transmission line coupler 104 receives the sine wave signals from the first AC signal source 101 and the second AC signal source 601, both of which have different frequencies. The second transmission line coupler 105 is movable relative to the first transmission line coupler 104.

[0085] The bandpass filter 604 outputs only the frequency component of the sine wave signal of the first AC signal source 101 from the signal output from one end of the second transmission line coupler 105. The other end of the second transmission line coupler 105 is matched termination.

[0086] The phase difference detection unit 106 detects the phase difference between the signal output from the bandpass filter 604 and the sine wave signal from the first AC signal source 101. The phase difference detection unit 606 also detects the phase difference between the signal output from the bandpass filter 605 and the sine wave signal from the second AC signal source 601.

[0087] The difference unit 607 outputs the difference between the phase difference detected by the phase difference detection unit 106 and the phase difference detected by the phase difference detection unit 606.

[0088] The first transmission line coupler 104 has a sine wave signal from the first AC signal source 101 and a sine wave signal from the second AC signal source 601 input to one end, and the other end is matched and terminated. The first transmission line coupler 104 and the second transmission line coupler 105 are both straight in shape, and the first transmission line coupler 104 is longer than the second transmission line coupler 105.

[0089] (Fourth embodiment) Figure 8 shows an example configuration of a displacement measurement system 800 according to the fourth embodiment. The displacement measurement system 800 includes an AC signal source 801, a first cable 802, a second cable 803, a first transmission line coupler 804, a second transmission line coupler 805, a first circular coupler 806, a second circular coupler 807, a third cable 808, a phase difference detection unit 809, a counting unit 810, and a resistor 811.

[0090] The AC signal source 801 outputs a sine wave signal of any frequency to the first transmission line coupler 804 via the first cable 802. The AC signal source 801 also outputs a sine wave signal of any frequency to the line end of the first circular coupler 806 via the second cable 803.

[0091] The first transmission line coupler 804 is a transmission line with a circular shape, into which a signal from an AC signal source 801 is input from one end of the line, and the other end is terminated with a resistor 811 that is equal to the characteristic impedance of the transmission line.

[0092] The second transmission line coupler 805 is an arc-shaped transmission line, with the same center and radius as the first transmission line coupler 804. Furthermore, the length of the second transmission line coupler 805 is shorter than that of the first transmission line coupler 804, and it orbits the circumference while maintaining a constant distance from the first transmission line coupler 804.

[0093] The centers of the first circular coupler 806 and the second circular coupler 807 are the same as the center of the circle of the first transmission line coupler 804. The first circular coupler 806 wirelessly transmits the output signal of the AC signal source 801 to the second circular coupler 807.

[0094] The second circular coupler 807 outputs a signal to the phase difference detection unit 809 via the third cable 808.

[0095] The first transmission line coupler 804 and the second transmission line coupler 805 function as directional couplers. When the traveling wave of the first transmission line coupler 804 couples with the second transmission line coupler 805, there are two coupling paths, path A and path B.

[0096] Path A shows the case where the traveling wave of the first transmission line coupler 804 couples without passing through the coupling terminal of the second transmission line coupler 805. Path B shows the case where the traveling wave of the first transmission line coupler 804 couples via the coupling terminal of the second transmission line coupler 805.

[0097] Here, let θ1 be the angle formed by the line segment from the center of the circle to the signal input terminal of the first transmission line coupler 804 and the line segment from the center of the circle to the disconnect terminal of the second transmission line coupler 805. Let θ2 be the angle formed by the line segment from the center of the circle to the disconnect terminal of the second transmission line coupler 805 and the line segment from the center of the circle to the coupling terminal of the second transmission line coupler 805. Let θ3 be the angle formed by the line segment from the center of the circle to the coupling terminal of the second transmission line coupler 805 and the line segment from the center of the circle to the resistor termination of the first transmission line coupler 804. Also, let r be the radius of the circle.

[0098] The signal input to the signal input terminal of the first transmission line coupler 804 is the same as the signal S1 in the first embodiment.

[0099] First, let's explain path A. The angle formed by the line segment from the center of the circle to the signal input terminal of the first transmission line coupler 804 and the line segment from the center of the circle to an arbitrary position on the second transmission line coupler 805 is θ. A The signal S6 at the disconnected end of the second transmission line coupler 805 is expressed by equation 12.

[0100]

number

[0101] The coefficient k represents the degree of coupling per unit length. The wavelength λ represents the wavelength of the sinusoidal signal generated by the AC signal source 801. Due to the difference in length between the second cable 803 and the third cable 808, the difference in length of the first cable 802, and the wireless transmission between the first circular coupler 806 and the second circular coupler 807, a phase difference occurs between the first transmission line coupler 804 and the sinusoidal signal input to the phase difference detection unit 809, and this phase difference is defined as θ0.

[0102] The third term in parentheses in Equation 12 represents the phase change when the traveling wave is transmitted over the first transmission line coupler 804, and the fourth term represents the phase change when the traveling wave is transmitted over the second transmission line coupler 805. Solving Equation 12, the signal S6 is expressed in Equation 13.

[0103]

number

[0104] Next, let's explain path B. The angle formed by the line segment from the center of the circle to the coupling end of the second transmission line coupler 805 and the line segment from the center of the circle to an arbitrary position on the second transmission line coupler 805 is θ. B The signal S7 at the disconnected end of the second transmission line coupler 805 is expressed by equation 14.

[0105]

number

[0106] The third term in parentheses in Equation 14 represents the phase change when the traveling wave is transmitted over the first transmission line coupler 804, and the fourth term represents the phase change when the traveling wave is transmitted over the second transmission line coupler 805. Solving Equation 14, the signal S7 is expressed in Equation 15.

[0107]

number

[0108] When the radius r is N times the wavelength λ (N: a natural number), or when the frequency of the signal generated by the AC signal source 801 is r / N, equation 15 can be expressed as equation 16.

[0109]

number

[0110] When the signal input terminal and resistor termination of the first transmission line coupler 804, that is, the circumferential notch, and the second transmission line coupler 805 overlap vertically, the signal S8, which is the sum of path A and path B, is output to the disconnected terminal of the second transmission line coupler 805. Signal S8 is represented by Equation 17.

[0111]

number

[0112] Furthermore, if the circumferential notch and the second transmission line coupler 805 do not overlap vertically, only the signal of path A is output to the disconnected end of the second transmission line coupler 805. In both cases, whether the circumferential notch and the second transmission line coupler 805 overlap vertically or not, the phase difference detection unit 809 detects and outputs the phase difference Δθ between the sinusoidal signal S1 generated by the AC signal source 801 and the signal S6 or signal S8 at the disconnected end of the second transmission line coupler 805. The phase difference Δθ is expressed by Equation 18.

[0113]

number

[0114] In other words, the phase difference Δθ output by the phase difference detection unit 809 allows for the measurement of the displacement rθ1 of the second transmission line coupler 805 relative to the first transmission line coupler 804. However, the radius r is N times the wavelength λ (N: a natural number), or the frequency of the signal generated by the AC signal source 801 is r / N.

[0115] The counting unit 810, with an initial value of 0 for the internal counter and the initial output of the phase difference detection unit 809 as the initial phase difference, subtracts 1 from the internal counter when the second transmission line coupler 805 moves to the signal input end side of the first transmission line coupler 804 and the phase difference rotates 360 degrees back to the initial phase difference. Also, the counting unit 810 adds 1 to the internal counter when the second transmission line coupler 805 moves to the resistor termination side of the first transmission line coupler 804 and the phase difference rotates 360 degrees back to the initial phase difference.

[0116] Furthermore, in the displacement measurement system 800, the output of the phase difference detection unit 806 and the output of the counting unit 807 are input to a displacement calculation unit (not shown) that calculates the displacement, and the displacement rθ1 of the second transmission line coupler 805 relative to the first transmission line coupler 804 is calculated.

[0117] Figure 9 shows the relationship between the displacement and phase difference of the transmission line coupler according to this embodiment. The horizontal axis represents the position of the second transmission line coupler 805 when the signal input terminal of the first transmission line coupler 804 is set to 0 mm, and the vertical axis represents the phase difference Δθ output by the phase difference detection unit 809. For example, there are four positions of the second transmission line coupler 805 where the phase difference Δθ = 0, which are around 80 mm, 170 mm, 260 mm, and 350 mm. The output values ​​of the counting unit 810 are 1, 2, 3, and 4, respectively, and even with the same phase difference, the position of the second transmission line coupler 805 can be identified from the output value of the counting unit 810.

[0118] As described above, with this embodiment, the position of the second transmission line coupler 805 relative to the first transmission line coupler 804 can be calculated by the output of the phase difference detection unit 809 and the output of the counting unit 810.

[0119] In this embodiment, the same results can be obtained even if the second transmission line coupler 805 is replaced with a capacitive coupler.

[0120] As described above, the first transmission line coupler 804 has a circular shape. The second transmission line coupler 805 has an arc shape. The centers and radii r of the circles of the first transmission line coupler 804 and the second transmission line coupler 805 are the same. The second transmission line coupler 805 can move around the circumference while maintaining a constant distance from the first transmission line coupler 804.

[0121] The radius r of the circle is a natural number multiple of the wavelength λ of the sinusoidal signal of the AC signal source 801, or the frequency of the sinusoidal signal of the AC signal source 801 is a natural number divisor of the radius r of the circle.

[0122] The AC signal source 801 is connected to the first transmission line coupler 804. The first circular coupler 806 is connected to the AC signal source 801. The second circular coupler 807 faces the first circular coupler 806 and is connected to the phase difference detection unit 809.

[0123] (Fifth embodiment) Figure 10 shows an example configuration of the displacement measurement system 1000 according to the fifth embodiment. In addition to the configuration of the displacement measurement system 800 of the fourth embodiment, the displacement measurement system 1000 includes a second AC signal source 1001, a fourth cable 1002, a fifth cable 1003, a sixth cable 1004, bandpass filters 1005, 1006, 1007, and 1008, a phase difference detection unit 1009, and a difference unit 1010.

[0124] Note that the counting unit 810 in Figure 8 is unnecessary and has been omitted from the configuration. In this embodiment, the AC signal source 801 is referred to as the first AC signal source 801. The frequencies of the sine wave signals generated by the first AC signal source 801 and the second AC signal source 1001 are assumed to be different.

[0125] The second AC signal source 1001 outputs a sine wave signal to the signal input terminal of the first transmission line coupler 804 via the fourth cable 1002. The second AC signal source 1001 also outputs a sine wave signal to the first circular coupler 806 via the fifth cable 1003.

[0126] The second circular coupler 807 outputs a signal to the bandpass filter 1006 via the third cable 808, and also outputs a signal to the bandpass filter 1008 via the sixth cable 1004.

[0127] The bandpass filter 1005 allows only the frequency component of the sine wave signal generated by the first AC signal source 801 to pass through the signal output from the isolated end of the second transmission line coupler 805, and outputs it to the phase difference detection unit 809. The bandpass filter 1006 allows only the frequency component of the sine wave signal generated by the first AC signal source 801 to pass through the signal output from the second circular coupler 807, and outputs it to the phase difference detection unit 809.

[0128] The bandpass filter 1007 allows only the frequency component of the sine wave signal generated by the second AC signal source 1001 to pass through the signal output from the isolated end of the second transmission line coupler 805, and outputs it to the phase difference detection unit 1009. The bandpass filter 1008 allows only the frequency component of the sine wave signal generated by the second AC signal source 1001 to pass through the signal output from the second circular coupler 807, and outputs it to the phase difference detection unit 1009.

[0129] The phase difference detection unit 809 detects and outputs the phase difference between the sinusoidal signal generated by the first AC signal source 801 and the signal that has passed through the bandpass filter 1005 from the separated end of the second transmission line coupler 805.

[0130] The phase difference detection unit 1009 detects and outputs the phase difference between the sinusoidal signal generated by the second AC signal source 1001 and the signal that has passed through the bandpass filter 1007 from the separated end of the second transmission line coupler 805.

[0131] The principle by which the displacement of the second transmission line coupler 805 relative to the first transmission line coupler 804 can be measured using the phase difference Δθ output by the phase difference detection units 809 and 1009 is the same as in the fourth embodiment.

[0132] The difference unit 1010 outputs the difference between the phase difference output by the phase difference detection unit 809 and the phase difference output by the phase difference detection unit 1009.

[0133] Furthermore, the displacement measurement system 1000 inputs the output of the difference unit 1010 to a displacement calculation unit (not shown) and calculates the displacement rθ1 of the second transmission line coupler 805 relative to the first transmission line coupler 804.

[0134] Figure 11 shows the relationship between the displacement and phase difference of the transmission line coupler according to this embodiment. In Figure 11(a), the horizontal axis represents the position of the second transmission line coupler 805 when the signal input terminal of the first transmission line coupler 804 is set to 0 mm, and the vertical axis represents the phase difference output by the phase difference detection units 809 and 1009. The frequency of the first AC signal source 801 is 5.56 GHz, and the frequency of the second AC signal source 1001 is 6.95 GHz.

[0135] Figure 7(b) shows the position of the second transmission line coupler 805 on the horizontal axis, with the signal input terminal of the first transmission line coupler 804 set to 0 mm, and the difference in the outputs of the two phase difference detection units 809 and 1009 on the vertical axis. From Figure 7(b), it can be seen that the difference in the outputs of the two phase difference detection units 809 and 1009 becomes an eigenvalue depending on the position of the second transmission line coupler 805.

[0136] As described above, with this embodiment, the absolute position of the second transmission line coupler 805 can be calculated by the difference between the outputs of the two phase difference detection units 809 and 1009.

[0137] In this embodiment as well, the second transmission line coupler 805 may be replaced with a capacitive coupler.

[0138] As described above, the first transmission line coupler 804 has a circular shape, and the second transmission line coupler 805 has an arc shape. The centers and radii r of the circles of the first transmission line coupler 804 and the second transmission line coupler 805 are the same.

[0139] The first circular coupler 806 receives the sine wave signal from the first AC signal source 801 and the sine wave signal from the second AC signal source 1001. The second circular coupler 807 faces the first circular coupler 806.

[0140] The bandpass filter 1006 outputs only the frequency component of the sine wave signal of the first AC signal source 801 from the signal output from the second circular coupler 807. The bandpass filter 1008 outputs only the frequency component of the sine wave signal of the second AC signal source 1001 from the signal output from the second circular coupler 807.

[0141] The phase difference detection unit 809 receives the output signals from the bandpass filter 1005 and the bandpass filter 1006. The phase difference detection unit 1009 also receives the output signals from the bandpass filter 1007 and the bandpass filter 1008.

[0142] As described above, according to the first to fifth embodiments, the detection accuracy of the position of the second transmission line coupler relative to the first transmission line coupler can be kept constant.

[0143] (Other embodiments) This disclosure can also be implemented by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions.

[0144] Furthermore, the embodiments described above are merely examples illustrating how to implement this disclosure, and they should not be interpreted as limiting the technical scope of this disclosure. In other words, this disclosure can be implemented in various ways without departing from its technical concept or its main features.

[0145] This embodiment includes the following configuration. (Item 1) A first transmission line coupler into which a first signal containing a first frequency component is input, A second transmission line coupler that is movable relative to the first transmission line coupler, A phase difference detection unit detects the phase difference between the signal of the first frequency component output from the second transmission line coupler and the second signal of the first frequency. The counting unit changes the value of an internal counter each time the phase difference rotates 360 degrees. A displacement measurement system characterized by having the following features. (Item 2) The displacement measurement system according to item 1, further comprising means for determining the position of the second transmission line coupler relative to the first transmission line coupler from the phase difference and the value of the internal counter. (Item 3) The first signal is a signal of the first frequency, The displacement measurement system according to item 1 or 2, characterized in that the phase difference detection unit detects the phase difference between the signal output from the second transmission line coupler and the second signal. (Item 4) The displacement measurement system according to item 3, further comprising an AC signal source that outputs the first signal and the second signal. (Item 5) The phase difference detection unit detects the phase difference between the signal output from one end of the second transmission line coupler and the second signal. The displacement measurement system according to any one of items 1 to 4, characterized in that the other end of the second transmission line coupler is terminated in a matched manner. (Item 6) The system further includes a filter that outputs the signal of the first frequency component of the signal output from the second transmission line coupler, The displacement measurement system according to item 1 or 2, characterized in that the phase difference detection unit detects the phase difference between the signal output from the filter and the second signal. (Item 7) The displacement measurement system according to item 6, further comprising an adder that adds the second signal and the third signal and outputs the first signal to the first transmission line coupler. (Item 8) The displacement measurement system according to item 7, characterized in that the first frequency is higher than the frequency of the third signal. (Item 9) The displacement measurement system according to item 7 or 8, further comprising an AC signal source that outputs the second signal to the phase difference detection unit and the adder. (Item 10) The filter outputs the signal of the first frequency component of the signal output from one end of the second transmission line coupler. The displacement measurement system according to item 9, further comprising a comparator that compares a signal output from the other end of the second transmission line coupler with a threshold value. (Item 11) The displacement measurement system according to item 10, characterized in that the output signal of the comparator is a signal in which the third signal has been delayed. (Item 12) The displacement measurement system according to item 10 or 11, characterized in that the third signal is a digital data signal. (Item 13) The displacement measurement system according to item 12, characterized in that the second signal is a sinusoidal signal. (Item 14) The displacement measurement system according to any one of items 1 to 5, characterized in that the first signal and the second signal are sinusoidal signals. (Item 15) The first transmission line coupler and the second transmission line coupler each have a straight shape. The displacement measuring system according to any one of items 1 to 14, characterized in that the first transmission line coupler is longer than the second transmission line coupler. (Item 16) The displacement measuring system according to any one of items 1 to 15, characterized in that the second transmission line coupler is movable horizontally while maintaining a certain distance from the first transmission line coupler. (Item 17) The first transmission line coupler has a circular shape, The second transmission line coupler has an arc shape, The displacement measuring system according to any one of items 1 to 14, characterized in that the centers and radii of the circles of the first transmission line coupler and the second transmission line coupler are the same. (Item 18) The displacement measuring system according to item 17, characterized in that the second transmission line coupler is movable around the circumference while maintaining a constant distance from the first transmission line coupler. (Item 19) The displacement measuring system according to item 17 or 18, characterized in that the radius of the circle is a natural number multiple of the wavelength of the second signal, or the first frequency is a divisor of the radius of the circle by a natural number. (Item 20) An AC signal source connected to the first transmission line coupler, A first circular coupler connected to the AC signal source, The displacement measuring system according to any one of items 17 to 19, further comprising a second circular coupler that faces the first circular coupler and is connected to the phase difference detection unit. (Item 21) The displacement measurement system according to any one of items 1 to 20, characterized in that the first transmission line coupler has the first signal input to one end and the other end is matched and terminated. (Item 22) The displacement measuring system according to any one of items 1 to 21, characterized in that the first transmission line coupler and the second transmission line coupler function as directional couplers. (Item 23) The displacement measuring system according to any one of items 1 to 21, characterized in that the second transmission line coupler is capacitively coupled with the first transmission line coupler and functions as a capacitive coupling coupler. (Item 24) The displacement measurement system according to any one of items 1 to 23, characterized in that the phase difference detection unit orthogonally demodulates two input signals and detects the phase difference by converting the orthogonally demodulated signals into polar coordinates. (Item 25) The displacement measurement system according to item 21, characterized in that the counting unit stores the initial output value of the phase difference detection unit as the initial phase difference, sets the initial value of the internal counter to 0, subtracts 1 from the internal counter when the second transmission line coupler moves toward the one end of the first transmission line coupler and the phase difference rotates by 360 degrees, and adds 1 to the internal counter when the second transmission line coupler moves toward the other end of the first transmission line coupler and the phase difference rotates by 360 degrees. (Item 26) A first transmission line coupler into which a first signal and a second signal with mutually different frequencies are input, A second transmission line coupler that is movable relative to the first transmission line coupler, A first filter that outputs only the frequency component of the first signal from the signal output from the second transmission line coupler, A second filter that outputs only the frequency component of the second signal from the signal output from the second transmission line coupler, A first phase difference detection unit detects the phase difference between the signal output from the first filter and the first signal, A second phase difference detection unit detects the phase difference between the signal output from the second filter and the second signal. A displacement measurement system characterized by having the following features. (Item 27) The displacement measurement system according to item 26, further comprising a difference unit that outputs the difference between the phase difference detected by the first phase difference detection unit and the phase difference detected by the second phase difference detection unit. (Item 28) The first filter outputs only the frequency component of the first signal from the signal output from one end of the second transmission line coupler. The second filter outputs only the frequency component of the second signal from the signal output from one end of the second transmission line coupler. The displacement measurement system according to item 26 or 27, characterized in that the other end of the second transmission line coupler is terminated in a matched manner. (Item 29) The displacement measurement system according to any one of items 26 to 28, characterized in that the first transmission line coupler has the first signal and the second signal input to one end and the other end is matched and terminated. (Item 30) The first transmission line coupler and the second transmission line coupler each have a straight shape. The displacement measuring system according to any one of items 26 to 29, characterized in that the first transmission line coupler is longer than the second transmission line coupler. (Item 31) The first transmission line coupler has a circular shape, The second transmission line coupler has an arc shape, The displacement measuring system according to any one of items 26 to 29, characterized in that the centers and radii of the circles of the first transmission line coupler and the second transmission line coupler are the same. (Item 32) A first circular coupler into which the first signal and the second signal are input, A second circular coupler opposite to the first circular coupler, A third filter that outputs only the frequency component of the first signal from the signal output from the second circular coupler, It has a fourth filter that outputs only the frequency component of the second signal from the signal output from the second circular coupler, The first phase difference detection unit receives the output signal of the first filter and the output signal of the third filter, The displacement measurement system according to item 31, characterized in that the second phase difference detection unit receives the output signal of the second filter and the output signal of the fourth filter. (Item 33) A first transmission line coupler into which a first signal containing a first frequency component is input, A processing method for a displacement measuring system having a second transmission line coupler that is movable relative to the first transmission line coupler, A phase difference detection step for detecting the phase difference between the signal of the first frequency component output from the second transmission line coupler and the second signal of the first frequency, A counting step in which the value of an internal counter is changed each time the phase difference rotates 360 degrees. A processing method for a displacement measurement system, characterized by having the following features. (Item 34) A first transmission line coupler into which a first signal and a second signal with mutually different frequencies are input, A processing method for a displacement measuring system having a second transmission line coupler that is movable relative to the first transmission line coupler, A first filter step that outputs only the frequency component of the first signal from the signal output from the second transmission line coupler, A second filter step that outputs only the frequency component of the second signal from the signal output from the second transmission line coupler, A first phase difference detection step that detects the phase difference between the signal output in the first filtering step and the first signal, A second phase difference detection step that detects the phase difference between the signal output in the second filtering step and the second signal. A processing method for a displacement measurement system, characterized by having the following features. [Explanation of Symbols]

[0146] 100, 800 Displacement Measurement System 101, 801 AC signal source 102, 802 First cable 103, 803 Second cable 104, 804 First transmission line coupler 105, 805 Second transmission line coupler 106, 606, 809, 1009 Phase difference detection unit 107, 810 Counting Unit 201 90 degree phase shifter 202, 203 multiplier 204, 205 Low-pass filters 206 Polar Coordinate Transformation Section 401 Data signal source 402 Adder 403, 602, 808 Third Cable 404, 604, 605, 1005, 1006, 1007, 1008 Bandpass Filters 405 Comparator 406 Constant voltage source 601, 1001 Second AC signal source 603 Fourth Cable 806 First circular coupler 807 Second circular coupler 1002 Fourth Cable 1003 Fifth Cable 1004 The sixth cable

Claims

1. A first transmission line coupler into which a first signal containing a first frequency component is input, A second transmission line coupler that is movable relative to the first transmission line coupler, A phase difference detection unit detects the phase difference between the signal of the first frequency component output from the second transmission line coupler and the second signal of the first frequency. The counting unit changes the value of an internal counter each time the phase difference rotates 360 degrees. A displacement measurement system characterized by having the following features.

2. The displacement measuring system according to claim 1, further comprising means for determining the position of the second transmission line coupler relative to the first transmission line coupler from the phase difference and the value of the internal counter.

3. The first signal is a signal of the first frequency, The displacement measurement system according to claim 1, characterized in that the phase difference detection unit detects the phase difference between the signal output from the second transmission line coupler and the second signal.

4. The displacement measurement system according to claim 3, further comprising an AC signal source that outputs the first signal and the second signal.

5. The phase difference detection unit detects the phase difference between the signal output from one end of the second transmission line coupler and the second signal. The displacement measurement system according to claim 1, characterized in that the other end of the second transmission line coupler is terminated in a matched manner.

6. The system further includes a filter that outputs the signal of the first frequency component of the signal output from the second transmission line coupler, The displacement measurement system according to claim 1, characterized in that the phase difference detection unit detects the phase difference between the signal output from the filter and the second signal.

7. The displacement measurement system according to claim 6, further comprising an adder that adds the second signal and the third signal and outputs the first signal to the first transmission line coupler.

8. The displacement measuring system according to claim 7, characterized in that the first frequency is higher than the frequency of the third signal.

9. The displacement measurement system according to claim 7, further comprising an AC signal source that outputs the second signal to the phase difference detection unit and the adder.

10. The filter outputs the signal of the first frequency component of the signal output from one end of the second transmission line coupler. The displacement measurement system according to claim 9, further comprising a comparator that compares a signal output from the other end of the second transmission line coupler with a threshold value.

11. The displacement measurement system according to claim 10, characterized in that the output signal of the comparator is a signal obtained by delaying the third signal.

12. The displacement measurement system according to claim 10, characterized in that the third signal is a digital data signal.

13. The displacement measurement system according to claim 12, characterized in that the second signal is a sinusoidal signal.

14. The displacement measurement system according to claim 1, characterized in that the first signal and the second signal are sinusoidal signals.

15. The first transmission line coupler and the second transmission line coupler each have a straight shape. The displacement measuring system according to claim 1, characterized in that the first transmission line coupler is longer than the second transmission line coupler.

16. The displacement measuring system according to claim 1, characterized in that the second transmission line coupler is movable horizontally while maintaining a constant distance from the first transmission line coupler.

17. The first transmission line coupler has a circular shape, The second transmission line coupler has an arc shape, The displacement measuring system according to claim 1, characterized in that the centers and radii of the circles of the first transmission line coupler and the second transmission line coupler are the same.

18. The displacement measuring system according to claim 17, characterized in that the second transmission line coupler is movable around the circumference while maintaining a constant distance from the first transmission line coupler.

19. The displacement measurement system according to claim 17, characterized in that the radius of the circle is a natural number multiple of the wavelength of the second signal, or the first frequency is a divisor of the radius of the circle by a natural number.

20. An AC signal source connected to the first transmission line coupler, A first circular coupler connected to the AC signal source, The displacement measuring system according to claim 17, further comprising a second circular coupler that faces the first circular coupler and is connected to the phase difference detection unit.

21. The displacement measurement system according to claim 1, characterized in that the first transmission line coupler has the first signal input to one end and the other end is coupled and terminated.

22. The displacement measuring system according to claim 1, characterized in that the first transmission line coupler and the second transmission line coupler function as directional couplers.

23. The displacement measuring system according to claim 1, characterized in that the second transmission line coupler is capacitively coupled with the first transmission line coupler and functions as a capacitive coupling coupler.

24. The displacement measurement system according to claim 1, characterized in that the phase difference detection unit orthogonally demodulates two input signals and detects the phase difference by converting the orthogonally demodulated signals into polar coordinates.

25. The displacement measurement system according to claim 21, characterized in that the counting unit stores the first output value of the phase difference detection unit as the initial phase difference, sets the initial value of the internal counter to 0, subtracts 1 from the internal counter when the second transmission line coupler moves toward one end of the first transmission line coupler and the phase difference rotates by 360 degrees, and adds 1 to the internal counter when the second transmission line coupler moves toward the other end of the first transmission line coupler and the phase difference rotates by 360 degrees.

26. A first transmission line coupler into which a first signal and a second signal with mutually different frequencies are input, A second transmission line coupler that is movable relative to the first transmission line coupler, A first filter that outputs only the frequency component of the first signal from the signal output from the second transmission line coupler, A second filter that outputs only the frequency component of the second signal from the signal output from the second transmission line coupler, A first phase difference detection unit detects the phase difference between the signal output from the first filter and the first signal, A second phase difference detection unit detects the phase difference between the signal output from the second filter and the second signal. A displacement measurement system characterized by having the following features.

27. The displacement measurement system according to claim 26, further comprising a difference unit that outputs the difference between the phase difference detected by the first phase difference detection unit and the phase difference detected by the second phase difference detection unit.

28. The first filter outputs only the frequency component of the first signal from the signal output from one end of the second transmission line coupler. The second filter outputs only the frequency component of the second signal from the signal output from one end of the second transmission line coupler. The displacement measurement system according to claim 26, characterized in that the other end of the second transmission line coupler is terminated in a matching manner.

29. The displacement measurement system according to claim 26, characterized in that the first transmission line coupler has the first signal and the second signal input to one end and the other end is matched and terminated.

30. The first transmission line coupler and the second transmission line coupler each have a straight shape. The displacement measuring system according to claim 26, characterized in that the first transmission line coupler is longer than the second transmission line coupler.

31. The first transmission line coupler has a circular shape, The second transmission line coupler has an arc shape, The displacement measuring system according to claim 26, characterized in that the centers and radii of the circles of the first transmission line coupler and the second transmission line coupler are the same.

32. A first circular coupler into which the first signal and the second signal are input, A second circular coupler opposite to the first circular coupler, A third filter that outputs only the frequency component of the first signal from the signal output from the second circular coupler, It has a fourth filter that outputs only the frequency component of the second signal from the signal output from the second circular coupler, The first phase difference detection unit receives the output signal of the first filter and the output signal of the third filter, The displacement measurement system according to claim 31, characterized in that the second phase difference detection unit receives the output signal of the second filter and the output signal of the fourth filter.

33. A first transmission line coupler into which a first signal containing a first frequency component is input, A processing method for a displacement measuring system having a second transmission line coupler that is movable relative to the first transmission line coupler, A phase difference detection step for detecting the phase difference between the signal of the first frequency component output from the second transmission line coupler and the second signal of the first frequency, A counting step in which the value of an internal counter is changed each time the phase difference rotates 360 degrees. A processing method for a displacement measurement system, characterized by having the following features.

34. A first transmission line coupler into which a first signal and a second signal with mutually different frequencies are input, A processing method for a displacement measuring system having a second transmission line coupler that is movable relative to the first transmission line coupler, A first filter step that outputs only the frequency component of the first signal from the signal output from the second transmission line coupler, A second filter step that outputs only the frequency component of the second signal from the signal output from the second transmission line coupler, A first phase difference detection step that detects the phase difference between the signal output in the first filtering step and the first signal, A second phase difference detection step that detects the phase difference between the signal output in the second filtering step and the second signal. A processing method for a displacement measurement system, characterized by having the following features.

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