JP2020058019A - Measurement method, transmission line diagnostic device, detection device, and linear sensor device - Google Patents

Abstract

To provide a measurement method enabling a change in a transmission line to be easily detected with simple configuration.SOLUTION: A measurement system 1 comprises: a communication instrument A; a communication instrument B; a pair of differential transmission lines 10 including two transmission lines; a combiner 5; and a measuring instrument C. The communication instrument A and the communication instrument B transmit and receive a positive signal and a negative signal having polarities reverse to each other via the differential transmission lines 10. The combiner 5 combines the positive signal and the negative signal exchanged between the communication instruments A and B as they are (non-inverted) to generate an in-phase signal. The measuring instrument C measures the in-phase signal output from the combiner 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a measurement method, a transmission line diagnosis device, a detection device, and a linear sensor device.

Measurement of a transmission line in a differential transmission line that transmits signals of opposite phases to a pair of signal lines is to measure a combined signal (differential signal) obtained by inverting and combining one of the signals with the other signal. Performed by FIG. 23 is a diagram illustrating a configuration of a measurement system 100 that detects a differential signal. Signals having phases opposite to each other are transmitted to a pair of signal lines (differential transmission cables) 110 connecting between the communication devices A and B. One of the signals taken out by the communication device A is inverted, and the other signal is inverted and synthesized by the synthesizer 101. The combined signal (differential signal) is input to the measuring device C and measured. FIG. 24 is a diagram illustrating a waveform example of a differential signal. The input signal I1 input to the driver D is transmitted through the differential transmission cable 110 as a positive signal and a negative signal, is synthesized by the receiver R, and is output as an output signal OD1. In a normal state, the output signal OD1 has the same waveform as the input signal I1, as shown in FIG. On the other hand, when an abnormality occurs in the transmission line, as shown in FIG.
The output signal OD2 has a different waveform from the input signal I1.

  When measuring the change in the transmission line by measuring the differential signal, the change in the composite signal is extremely small with respect to the change in the transmission line, and it is difficult to detect the change. For this reason, for example, as shown in Patent Literature 1, a device combining various methods has been proposed. Patent Documents 2 to 4 disclose techniques relating to cable diagnosis, Patent Documents 5 to 8 disclose techniques relating to a liquid level sensor, and Patent Documents 9 to 11 disclose techniques relating to a displacement sensor. Patent Documents 12 to 15 disclose technologies relating to a pressure sensor, Patent Documents 16 to 18 disclose technologies relating to an acceleration sensor, and Non-Patent Documents 1 and 2 disclose technologies relating to an optical fiber sensor.

JP-A-2017-92621 JP 2013-185864 A JP-A-2003-244034 JP 2010-276586 A JP-A-2015-4561 JP 2007-240472 A JP 2013-108958 A JP 2012-225788 A JP 2016-1123 A JP 2001-201363 A JP 2011-137748 A JP 2011-137746 A JP 2017-133841 A JP 2013-104797 A JP 2014-182031 A JP 2017-67500A JP 2013-160559 A JP 2011-185828 A

Michio Imai et al., “Structural Monitoring Using Optical Fiber Sensors”, IEICE General Conference 2019, BI-8-1, pp.SS-79-80, Mar. 19-22, 2019 Shu Mizuguchi et al., “Life Cycle Monitoring of Aerospace Composite Structure”, IEICE General Conference 2019, BI-8-2, pp.SS-81, Mar. 19-22, 2019

  According to the technique disclosed in Patent Literature 1, a measurement system for detecting a change in a transmission line becomes complicated.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a measurement method and a transmission line diagnostic device that can easily detect a change in a transmission line with a simple configuration. It is another object of the present invention to provide a compact and highly accurate liquid level detection device.

In order to achieve the above-mentioned object, a measurement method, a transmission line diagnosis device, a detection device, and a linear sensor device according to the present invention are characterized by the following (1) to (16).
(1) A pair of differential transmission lines including a first transmission line transmitting a first signal and a second transmission line transmitting a second signal having a phase opposite to that of the first signal are transmitted through the first transmission line. The first signal and the second signal transmitted through the second transmission line are combined to generate an in-phase signal,
Measuring the generated in-phase signal,
A measuring method characterized in that:
(2) amplifying the generated in-phase signal;
Measuring the amplified in-phase signal;
The measurement method according to the above (1), characterized in that:
(3) measuring the generated in-phase signal after attenuating a signal in a frequency band higher than a target frequency band,
The measuring method according to the above (1) or (2), wherein
(4) The first signal transmitted through the first transmission line and the second signal transmitted through the second transmission line are taken out by a directional coupler and combined.
The measuring method according to any one of the above (1) to (3), wherein
(5) a mounting portion to which a pair of differential transmission lines including a first transmission line transmitting the first signal and a second transmission line transmitting the second signal having a phase opposite to the first signal is mounted;
Via the mounting portion, a first communication unit that transmits the first signal and the first signal to the differential transmission path,
Through the mounting portion, a second communication unit that receives the first signal and the second signal from the differential transmission path,
A signal synthesizer that extracts the first signal and the second signal received by the second communication unit and combines them to generate an in-phase signal,
A detector for detecting the generated in-phase signal;
A determining unit that determines that an error has occurred when the detected magnitude of the in-phase signal is equal to or greater than a threshold,
A diagnostic device comprising:
(6) an amplifier for amplifying the in-phase signal generated by the signal synthesizer;
The detector detects the in-phase signal amplified by the amplifier,
The diagnostic device according to the above (5), wherein:
(7) The determining unit extracts the first signal and the second signal received by the second communication unit, and compares the first signal and the second signal with data of normal characteristics stored in a memory to determine whether the error has occurred. to decide,
The diagnostic device according to the above (5) or (6), wherein
(8) a first line to which a first signal is input;
A second line to which a second signal having a phase opposite to that of the first signal is input;
A combining unit that combines the first signal that has passed through the first line and the second signal that has passed through the second line to generate an in-phase signal,
A detection unit that detects a voltage of the generated common-mode signal,
A calculating unit for calculating a liquid level from the detected voltage,
A detection device comprising:
(9) an amplification unit that amplifies the generated in-phase signal,
The detection unit detects a voltage of the amplified in-phase signal,
The detection device according to the above (8), wherein:
(10) The calculating unit calculates the liquid level with reference to a table indicating a correspondence between the liquid level and the voltage.
The detection device according to the above (8) or (9), wherein
(11) The first line has a first open stub,
The second line has a second open stub,
The combining unit, the first signal that has passed through the first open stub, and the second signal that has passed through the second open stub, and combines the in-phase signal,
The detection device according to any one of the above (8) to (10), wherein
(12) a first sensor to which a first signal is input;
A second sensor to which a second signal having a phase opposite to the first signal is input,
A combining unit that combines the first signal that has passed through the first sensor and the second signal that has passed through the second sensor to generate an in-phase signal,
A detection unit that detects a voltage of the generated common-mode signal,
A calculating unit that calculates a displacement level or a pressure from the detected voltage,
A detection device comprising:
(13) At least one of the first sensor and the second sensor includes a loop coil,
The calculation unit calculates a distance between the loop coil and the measured object as the displacement level,
The detection device according to claim 12, wherein:
(14) Each of the first sensor and the second sensor includes a pair of electrode plates spaced apart from each other,
The calculation unit calculates a distance between the pair of electrode plates that changes due to pressure as the pressure,
The detection device according to claim 12, wherein:
(15) a movable electrode;
First and second fixed electrodes that are arranged apart from the movable electrode and face each other across the movable electrode,
The first signal that has passed between the movable electrode and the first fixed electrode, and the second signal that has passed between the movable electrode and the second fixed electrode, the voltage of the in-phase signal synthesized A detecting unit for detecting,
A calculating unit for calculating an acceleration from the detected voltage,
A detection device comprising:
(16) Two communication devices,
The first and second transmission lines having the same line length are arranged between the two communication devices,
A first signal that has passed through the first transmission path, and a second signal that has passed through the second transmission path, and a combiner that generates an in-phase signal by combining them.
A measuring instrument for measuring the generated in-phase signal,
A linear sensor device comprising:

  According to the measurement method of the above configuration (1), the in-phase signal synthesized without inverting the first signal and the second signal is a difference obtained by synthesizing the first signal and the inverted second signal. Since a difference in amplitude or phase between a pair of transmission lines can be grasped larger than a dynamic signal, a change in the transmission line can be easily detected, and the measurement system can be simplified.

  According to the measuring method having the configuration (2), a minute change in the transmission line can be easily detected by amplifying the in-phase signal.

  According to the measuring method of the above configuration (3), noise superimposed on unnecessary frequency bands can be removed, so that a more sensitive and stable detection output can be obtained.

  According to the measuring method having the configuration (4), when separating and extracting the original signal flowing through the differential transmission line, the loss of the original signal can be minimized. In addition, since it is possible to distinguish where the abnormality has occurred before and after based on the location (signal separation position) of the directional coupler, the function of the sensor of the differential transmission system can be improved.

  According to the diagnostic apparatus having the configuration of the above (5), the in-phase signal synthesized without inverting the first signal and the second signal is a difference obtained by synthesizing the first signal and the inverted second signal. Since a difference between the amplitude and the phase between the pair of transmission lines can be grasped larger than a dynamic signal, a change in the transmission line can be easily detected, and a minute error can be detected. Further, the present invention is not limited to a method using a diagnostic signal as the first signal and the second signal, and can be diagnosed using an actual communication signal, so that the versatility is high. When performing a diagnosis using a communication signal, a communication system using a differential transmission line (cable or the like) to be diagnosed can be used as it is, so that there is no need to separately construct a diagnostic system for inputting and outputting a diagnosis signal. The system can be simplified.

  According to the diagnostic device having the above configuration (6), a minute change in the transmission line can be easily detected by amplifying the in-phase signal.

According to the diagnostic device having the configuration of the above (7), even when a similar error occurs in the first transmission line and the second transmission line and no phase difference occurs between the first signal and the second signal. If there is a difference between the data of the first signal and the second signal and the data of the normal characteristic, it can be detected as an error,
High-precision diagnosis is possible.

  According to the detection device having the configuration (8), the first line is installed in a tank to be measured or the like for liquid level detection, and the second line is used as a reference for correction, so that the liquid level can be reduced. The corresponding difference appears as the level of the in-phase signal. That is, since a phase change, not an amplitude change, of the first signal and the second signal can be detected, the liquid level can be detected with high accuracy. Further, since the sensor is not a conventional capacitance detection type sensor, a linear pattern is sufficient, and a comb-shaped pattern for providing a capacitance to the substrate of the sensing unit is not required, so that the sensor shape can be made slim.

  According to the detection device having the above configuration (9), a minute change in the liquid level can be easily detected by amplifying the in-phase signal.

According to the detection device having the above configuration (10), the liquid level can be easily calculated by referring to the table prepared in advance.
According to the detection device having the configuration (11), the liquid level can be detected only by the open stub, and the element can be made slim.
According to the detection devices of (12) to (15), the displacement, pressure, and acceleration can be detected with high accuracy by using the in-phase signal synthesized without inverting the first signal and the second signal.
According to the linear sensor device of the above (16), it is possible to realize a linear sensor that compensates for the drawbacks of the optical fiber sensor (large conversion loss and low energy efficiency).

  According to the present invention, it is possible to provide a measurement method and a transmission line diagnostic device that can easily detect a change in a transmission line with a simple configuration. Further, a compact and highly accurate detection device can be provided.

  The present invention has been briefly described above. Further, details of the present invention will be further clarified by reading through embodiments for carrying out the invention described below (hereinafter, referred to as “embodiments”) with reference to the accompanying drawings. .

FIG. 1 is a diagram illustrating a configuration of a measurement system that detects an in-phase signal according to the first embodiment. FIG. 2 is a diagram illustrating a difference between a differential signal and a combined signal with respect to a phase shift. FIG. 3 is a diagram illustrating a waveform example of the in-phase signal. FIG. 4 is a diagram illustrating a configuration of a measurement system that detects an in-phase signal according to the second embodiment. FIG. 5 is a diagram illustrating a difference in the in-phase signal level depending on the presence or absence of amplification. FIG. 6 is a diagram illustrating a configuration of a measurement system that detects an in-phase signal according to the third embodiment. FIG. 7 is a diagram showing examples of common waveforms before and after removing unnecessary bands. FIG. 8 is a conceptual diagram of signal extraction using high impedance in the fourth embodiment. FIG. 9 is a conceptual diagram of signal extraction by the directional coupler according to the fourth embodiment. FIG. 10 is a conceptual diagram of signal extraction by the distributor / synthesizer in the fourth embodiment. FIG. 11 is a diagram illustrating a configuration of the cable diagnostic device according to the fifth embodiment. FIG. 12 is a diagram illustrating a modification of the fifth embodiment. FIG. 13 is a diagram illustrating a modification of the fifth embodiment. FIG. 14 is a diagram illustrating a cable diagnostic device according to a sixth embodiment. FIG. 15 is a diagram showing a flow of cable failure diagnosis in the cable diagnostic device of the sixth embodiment. FIG. 16 is a diagram illustrating a modification of the sixth embodiment. FIG. 17 is a diagram illustrating a modification of the sixth embodiment. FIG. 18 is a diagram illustrating a configuration of a liquid level detection device according to the seventh embodiment. FIG. 19 is a diagram illustrating a simulation model of a sensor unit in the liquid level detection device according to the seventh embodiment. FIG. 20 is a diagram showing a simulation result using the model shown in FIG. FIG. 21 is a diagram illustrating a modification of the seventh embodiment. FIG. 22 is a diagram illustrating a modification of the seventh embodiment. FIG. 23 is a diagram illustrating a configuration of a measurement system that detects a differential signal. FIG. 24 is a diagram illustrating a waveform example of a differential signal. FIG. 25 is a diagram illustrating a simulation model of a sensor unit in the liquid level detection device according to the eighth embodiment. FIG. 26 is a diagram illustrating the measurement principle of the liquid level detection device according to the eighth embodiment. FIG. 27 is a diagram showing a frequency characteristic result with respect to a liquid level change by a simulation using the model shown in FIG. FIG. 28 is a diagram showing a simulation result using the model shown in FIG. FIG. 29 is a diagram illustrating a modification of the eighth embodiment. FIG. 30 is a diagram illustrating a modification of the eighth embodiment. FIG. 31 is a diagram illustrating the configuration of the displacement detection device according to the ninth embodiment. FIG. 32 is a diagram illustrating a simulation model of a sensor unit in the displacement detection device according to the ninth embodiment. FIG. 33 is a diagram for explaining the measurement principle of the displacement detection device according to the ninth embodiment. FIG. 34 is a diagram illustrating a change in frequency characteristic according to a change in the distance of the metal block illustrated in FIG. 33. FIG. 35 is a diagram showing a simulation result using the model shown in FIG. FIG. 36 is a diagram showing a modification of the ninth embodiment. FIG. 37 is a diagram illustrating the configuration of the pressure detection device according to the tenth embodiment. FIG. 38 is a diagram illustrating a simulation model of a sensor unit in the pressure detection device according to the tenth embodiment. FIG. 39 is a diagram showing a change in frequency characteristics due to a change in the electrode plate interval (pressure change) shown in FIG. FIG. 40 is a diagram illustrating a simulation model of the sensor unit in the pressure detection device according to the tenth embodiment. FIG. 41 is a diagram illustrating a simulation result using the models illustrated in FIGS. 38 and 40. FIG. 42 is a diagram illustrating a modification of the tenth embodiment. FIG. 43 is a diagram showing a modification of the tenth embodiment. FIG. 44 is a diagram illustrating the configuration of the acceleration detection device according to the eleventh embodiment. FIG. 45 is a diagram illustrating a configuration of a sensor unit in the acceleration detection device according to the eleventh embodiment. FIG. 46 is a diagram showing a simulation model of the sensor unit shown in FIG. FIG. 47 is a diagram showing a simulation result (frequency characteristic change) using the model shown in FIG. FIG. 48 is a diagram showing a simulation result (output voltage change) using the model shown in FIG. FIG. 49 is a diagram illustrating a modification of the eleventh embodiment. FIG. 50 is a diagram illustrating a modification of the eleventh embodiment. FIG. 51 is an image diagram of the optical fiber sensor. FIG. 52 is a diagram illustrating a layout example of the linear sensor according to the twelfth embodiment.

  Specific embodiments of the present invention will be described below with reference to the drawings.

(First embodiment: measurement method)
FIG. 1 is a diagram illustrating a configuration of a measurement system 1 that detects an in-phase signal according to the first embodiment. The measurement system 1 includes a communication device A, a communication device B, a pair of differential transmission lines 10 including two transmission lines, a synthesizer 5, and a measuring device C. The communication device A and the communication device B transmit and receive, via the differential transmission line 10, a positive signal (first signal) and a negative signal (second signal) having opposite polarities to each other. The combiner 5 combines the positive signal and the negative signal exchanged between the communication device A and the communication device B in a non-inverted state to generate an in-phase signal. The measuring device C measures the in-phase signal output from the synthesizer 5. When a change, such as a change in physical shape or a change in material, occurs in a line for transmitting a positive signal or a line for transmitting a negative signal in the differential transmission line 10, the transmission for the transmission signal is performed at a place where the change occurs (an abnormal place). The characteristics change. Positive and negative signals that have passed through an abnormal part of the track are
Differences also occur in amplitude and phase. When an amplitude difference and a phase difference appear between a positive signal and a negative signal transmitted through two transmission lines between the communication device A and the communication device B, the in-phase signal is measured by the measuring device C. , A slight change in the transmission line can be detected.

FIG. 2 is a diagram illustrating a difference between a differential signal and a combined signal with respect to a phase shift. The function F1 is
23 shows a change in a differential signal due to an amplitude shift, and corresponds to a measurement result of a differential signal output from the combiner 101 shown in FIG. This differential signal is a signal obtained by inverting one of the positive signal and the negative signal transmitted by the differential transmission cable 110 and combining them. The function F2 indicates a change in the in-phase signal due to the phase shift, and corresponds to a measurement result of the in-phase signal output from the combiner 5 in FIG. According to FIG. 2, since the slope (change in amplitude) of the function F2 is larger than that of the function F1, the in-phase signal is more suitable for capturing a slight change than the differential signal. Recognize.

FIG. 3 is a diagram illustrating a waveform example of the in-phase signal. FIG. 3A shows an example of a waveform (common waveform) of the in-phase signal in a normal state, that is, when no abnormality occurs in the differential transmission line 10.
The input signal I1 input to the driver D is transmitted through the differential transmission line 10 as a positive signal and a negative signal, is added up by the combiner CB, and is output as an output signal OC1 (in-phase signal). Under normal conditions, there is no difference between the positive signal and the negative signal except that the polarities are opposite, so that when the two signals are added together, they cancel each other out and nothing remains. FIG.
(B) shows an example of the waveform of the in-phase signal when an abnormality occurs in the line for transmitting the negative signal of the differential transmission line 10. The input signal I1 input to the driver D is transmitted through the differential transmission line 10 as a positive signal and a negative signal, and then added by the combiner CB.
It is output as an output signal OC2 (in-phase signal). When there is a difference (difference) between the positive signal and the negative signal, when the two signals are added, an in-phase component (common signal) that cannot be canceled remains. The output signal OC2 is a sum of the common waveform OC21 generated by the amplitude difference, the common waveform OC22 generated by the phase difference, and the common waveform OC23 generated by the rise time difference.

The amount of the common signal (height of amplitude, time length, etc.) depends on (is proportional to) the difference between the positive signal and the negative signal. That is, since the amount of change in the common signal and the amount of change in the transmission line are in a proportional relationship, the change in the transmission line can be observed by observing an increase in the common signal from the normal state. For example, the degree of change can be observed by allocating a common signal amount in a normal state to the unit space of the Mahalanobis Taguchi system and subjecting a change (increase) in the common signal amount to a signal space for discrimination. By observing the transition of the change, it is possible to predict the degree of deterioration progress in the future. By predicting the degree of the degraded signal, the reliability of the communication network system and the services and functions using the same can be improved as follows. When an abnormality or a failure occurs in a device connected to the communication network or a transmission path configuring the communication network, a higher-order service or function that is established using the communication network is lost. Therefore, the measurement system 1 of the present embodiment diagnoses and extracts minute signs of devices and transmission lines related to the communication network, and predicts how long the signs will lead to what problems in the future. I do.
By estimating the degree of progress of deterioration in this way, it is possible to take measures against problems beforehand, and as a result, it is possible to improve the reliability of the communication network system and the services and functions using it.

  As described above, according to the measurement system 1 of the present embodiment, by using the in-phase signal as the measurement signal, it is possible to easily and accurately remove a slight change occurring in the transmission line without complicating the measurement system. Can be detected. Further, the reliability of the communication network system and the like can be improved by predicting the degree of progress of the deterioration of the transmission line using the measurement system 1 of the present embodiment.

(Second embodiment: measurement method)
FIG. 4 is a diagram illustrating a configuration of a measurement system 11 that detects an in-phase signal according to the second embodiment. The measurement system 11 includes a communication board 12, a communication board 13 including a communication chip 13a,
It includes a power adder 15, a low noise amplifier 17, a detector 18, a monitoring device 19, and a pair of differential cables 20 including two transmission lines. The differential cable 20 is connected between the communication board 12 and the communication board 13. The communication board 12 and the communication board 13 transmit and receive, via the differential cable 20, a positive signal and a negative signal whose polarities are opposite to each other. The power adder 15 combines the positive signal and the negative signal exchanged between the communication board 12 and the communication chip 13a in a non-inverted state to generate an in-phase signal. The low noise amplifier 17 amplifies the in-phase signal generated by the power adder 15. The detector 18 converts the amplitude level of the in-phase signal, which is a high-frequency signal, into an analog value and outputs the analog value as a detection voltage.
The monitoring device 19 observes a detection voltage (detection output) output from the detector 18. When an abnormality occurs in the differential cable 20 and an amplitude difference and a phase difference appear between the positive signal and the negative signal transmitted through the differential cable 20, the detection output from the detector 18 is observed by the monitoring device 19. As a result, a slight change in the transmission line can be detected. Since the in-phase signal is amplified by the low-noise amplifier 17, a slight change in the transmission line can be detected with high sensitivity. By amplifying the in-phase signal by, for example, about 30 dB by the low-noise amplifier 17, it is possible to easily confirm the change with a general wideband detector.

FIG. 5 is a diagram illustrating a difference in the in-phase signal level depending on the presence or absence of amplification. The graph shown in FIG. 5 shows the waveform (common waveform) W1 of the in-phase signal in the initial state of the differential cable 20 and the element (non-amplified) when an abnormality occurs in the differential cable 20 (abnormal state). And a common waveform W2 of
5 shows an amplified common waveform W3 when an abnormality occurs in the differential cable 20 (abnormal state). When amplification is not performed, the difference between the maximum values of the common waveforms W1 and W2 between the initial state and the abnormal state is about several tens mV. On the other hand, when amplification is performed, the difference between the maximum values of the common waveforms W1 and W3 between the initial state and the abnormal state is emphasized to several hundred mV. Thus, it can be easily seen from FIG. 5 that the ability to sense the change of the transmission line has been increased.

  In the present embodiment, the amplified signal is converted into a voltage by the detector 18 through effective value detection. This detection voltage is used as the sensor output. In the present embodiment, the detector 18 performs the effective value detection, but another detection method may be applied. Examples of the detection method include logarithmic (Log) detection, linear (linear) detection, a method using an average value, a peak value, an envelope of a diode, and a method of calculating an effective value by calculation using an IC. . Log detection is suitable for detecting a weak signal, and a voltage output corresponding to a high-frequency signal level (dBm) is obtained. Log detection has a wide range but a low resolution (accuracy). On the other hand, although linear detection is not suitable for detecting weak signals, a linear relationship is obtained between input and output. The linear detection has a narrow range but a high resolution (accuracy). The amplification of the in-phase signal in the present embodiment is effective for any detection method.

  As described above, according to the measurement system 11 of the present embodiment, in addition to the effects of the first embodiment, the sensitivity as a sensor can be improved by amplifying the in-phase signal.

(Third embodiment: measurement method)
FIG. 6 is a diagram illustrating a configuration of a measurement system 21 that detects an in-phase signal according to the third embodiment. 6 is obtained by adding a filter 16 to the measurement system 11 of the second embodiment shown in FIG. Hereinafter, the configuration different from the second embodiment will be mainly described.
The filter 16 attenuates a signal in a frequency band (unnecessary band) higher than a target frequency band. The filter 16 is arranged between the power adder 15 and the low noise amplifier 17.

  FIG. 7 is a diagram showing examples of common waveforms before and after removing unnecessary bands. When the in-phase signal of the differential digital transmission is used as a measurement signal, the detection level changes due to the influence of noise entering the wide band of the detector 18 and it is erroneously diagnosed that there is a change even though there is no change in the cable. May be lost. Therefore, the band other than the band necessary for information transmission is cut by the filter 16. FIG. 7A shows a common waveform when the filter 16 is not applied. FIG. 7B shows a common waveform when the filter 16 attenuates a frequency band of, for example, 80 MHz or more. When an effective common waveform appears only at 80 MHz or less, the noise superimposed on an unnecessary band can be removed by attenuating the frequency band of 80 MHz or more with the filter 16, and only the in-phase signal generated by a change in the transmission line can be removed. The used diagnosis can be performed.

表１において、検波出力の幅は、初期伝送路における検波出力電圧値と変化後の伝送路における検波出力電圧値との差である。初期伝送路において、フィルタ１６が無しの場合と有りの場合とで検波出力電圧値に差が見られるのは、本来伝送線路が変化しなければ現れないコモン波形以外に、ノイズが含まれてしまっているためである。変化後の伝送路において、フィルタ１６が無しの場合と有りの場合とで検波出力電圧値に差が見られるのは、伝送路の変化によって増加するコモン信号の周波数帯域に、ノイズの周波数帯域が重なっていることと、伝送路の変化によるコモン波形の変化の度合いがノイズよりも大きいことによる。フィルタ１６無しの場合における検波出力の幅１．０Ｖが、フィルタ１６有りの場合における検波出力の幅１．５Ｖよりも小さいことから、ノイズを除去しない場合は、伝送路の変化がノイズに埋もれてしまい、センサとしての感度が低下していることが分かる。逆に言えば、フィルタ１６によって不要帯域（ノイズ帯域）を除去することが、コモン波形を検波してセンサ出力を得る機能の感度を高めているといえる。 Table 1 shows the difference in the detection output voltage value depending on the presence or absence of the filter 16.

In Table 1, the width of the detection output is the difference between the detection output voltage value on the initial transmission line and the detection output voltage value on the changed transmission line. The difference in the detection output voltage between the case where the filter 16 is not provided and the case where the filter 16 is provided in the initial transmission line is due to the fact that noise is included in addition to the common waveform which does not appear unless the transmission line changes. Because it is. The difference in the detection output voltage between the case where the filter 16 is absent and the case where the filter 16 is present in the transmission line after the change is that the frequency band of the noise increases in the frequency band of the common signal which increases due to the change of the transmission line. This is due to the overlap and the fact that the degree of change of the common waveform due to the change of the transmission path is greater than noise. Since the width of the detection output 1.0 V without the filter 16 is smaller than the width of the detection output 1.5 V with the filter 16, when the noise is not removed, the change in the transmission path is buried in the noise. That is, it can be seen that the sensitivity as a sensor is reduced. Conversely, it can be said that the removal of the unnecessary band (noise band) by the filter 16 enhances the sensitivity of the function of detecting the common waveform and obtaining the sensor output.

  As described above, according to the measurement system 21 of the present embodiment, in addition to the effects of the first and second embodiments, a signal in a frequency band (unnecessary band) higher than a target frequency band is excluded. Thus, a stable detection output with higher sensitivity can be obtained.

(Fourth embodiment: measurement method)
In the present embodiment, a method of extracting an in-phase signal from a positive signal and a negative signal (original signal) to be received at a transmission destination in the measurement systems 1, 11, 21 described in the first to third embodiments. Will be described. In using the in-phase signal, it is important to extract the in-phase signal at a signal level as large as possible while minimizing the influence on the original signal. This is because a transmission standard is involved in an information transmission line, and it is not allowed to inadvertently attenuate or distort an original signal exchanged between communication devices. In the method of equivalently distributing and combining the original signals, the signal level of the original signals may be halved, and the minimum reception level defined by the communication standard may not be obtained. Therefore, as a signal extraction method for minimizing the reduction of the original signal level due to branching, the present inventors have proposed A) high impedance, B) directional coupler, C) coupler, divider, combiner (distribution combiner). The method used was devised. In the following, in FIG. 4, a distribution signal (distribution output) to the power adder 15 from an original signal (differential signal positive and differential signal negative) transmitted on the main transmission line from the differential cable 20 to the communication chip 13a. ) Will be described.

<A) Signal extraction method using high impedance>
FIG. 8 is a conceptual diagram of signal extraction by high impedance. In the method shown in FIG. 8, the line is branched with a high resistance value (a resistance amount that can be regarded as equivalent to open when viewed from the differential transmission line) so as not to affect the signal waveform of the original signal of the transmission line, and the distribution signal is divided. Is taken out.
According to this method, the distribution signal can be taken out very simply and inexpensively. On the other hand, since the signal is distributed by the resistance value, there are disadvantages in that the signal of the main transmission line is attenuated in accordance with the resistance ratio, and the signal is lost by the resistance itself.

<B) Signal extraction method using directional coupler>
FIG. 9 is a conceptual diagram of signal extraction by a directional coupler. The directional coupler is capable of separately extracting the traveling wave and the reflected wave, and is realized using, for example, a ferrite core transformer. Further, the directional coupler is used to obtain a standing wave ratio (VSWR: Voltage Standing Wave Ratio) from a ratio between the transmission power and the reflected power with respect to the load. Here, the signal of “communication board 12 → communication board 13” and the signal of “communication board 13 → communication board 12” in the two-way communication performed between the communication board 12 and the communication board 13 are defined as traveling wave output and reflected wave. It is used to separate output and output. By using the directional coupler, the loss of the original signal can be minimized. The loss of the original signal basically occurs only for the loss of the ferrite core. Further, since sufficient isolation (for example, 20 dB in power ratio) between the input / output terminal and the coupling output terminal can be obtained, the influence on the original signal can be reduced.

<C) Signal extraction method using distribution combiner>
FIGS. 10A and 10B are conceptual diagrams of signal extraction by the divider / combiner. FIG. 10A is a resistance distribution type, FIG. 10B is a transformer distribution type, FIG. 10C is a transformer and resistance hybrid type, and FIG. (D) shows an implementation example of the Wilkinson type. As the name implies, a divider / combiner, such as a coupler, a divider, or a combiner, is used to divide or add signal power. These are mainly for the purpose of distributing the signal power at a relatively close ratio, such as 1: 1 or 1:10, so that the level of the original signal is greatly reduced. In the resistance distribution type shown in FIG. 10A, distribution is performed by impedance matching with a resistance value. In this case, the ratio of the resistance values is the distribution ratio. Advantages of the resistance distribution type include a very simple structure and a wide band from DC to high frequency. On the other hand, since the signal is lost due to the resistance itself, there is a disadvantage that the total power amount after distribution is smaller than that before distribution. Further, since almost no isolation can be obtained between the original signal and the separation (distribution) destination, a reverse flow or inflow of the signal occurs due to a change in load, and the characteristics are not stable. The transformer distribution type shown in FIG. 10B uses a transformer instead of the resistor shown in FIG. Advantages of the transformer distribution type include a simple configuration and a small loss such as resistance distribution. On the other hand, since it is not a wide band and it is difficult to obtain isolation as in the case of the resistance distribution type, the disadvantage is that the characteristics are not stable. The hybrid type shown in FIG. 10C has a structure in which the resistance distribution type and the transformer type are mixed, and the merits include a wide band, low loss, and high isolation. On the other hand, there are disadvantages in that the number of parts increases and the configuration becomes complicated and the cost increases. The Wilkinson type shown in FIG. 10D realizes branching by a structure using a pattern of a microwave transmission line. As an advantage, there is no component other than the resistance for balance and low loss can be cited. On the other hand, because the performance depends on the width and length of the microstrip line, it is a narrow band type specialized for a specific frequency band, and the line length becomes longer depending on the frequency, so the measurement system becomes larger. This has disadvantages.

  As a signal extraction method for minimizing the influence on the original signal, it is desirable to use the directional coupler of B). By using this method, the signal of “communication board 12 → communication board 13” and the signal of “communication board 13 → communication board 12” can be individually taken out, which has advantages other than the original purpose. can get. That is, whether it is an abnormality included in the transmission line on the transmitter side, reflection due to impedance mismatch due to equipment failure on the receiver side, or abnormality of the signal transmitted from the receiver side, etc. The advantage is that it can also be used. That is, in the signal extraction using the directional coupler, it is possible to distinguish where the abnormality has occurred before and after the location of the directional coupler (signal separation position). In addition, by installing this function in a communication device connected to both ends of the differential transmission path, it becomes possible to determine which device is abnormal or the transmission line is abnormal. Therefore, the function as a sensor of the differential transmission system can be improved.

  As described above, by applying the signal extraction method using the directional coupler of the present embodiment to each measurement system of the first to third embodiments, the first embodiment to the third embodiment In addition to the effects described above, the following effects can be obtained. That is, when the original signal flowing through the differential transmission path is separated and taken out, the loss of the original signal can be minimized. In addition, since it is possible to distinguish where the abnormality has occurred before and after based on the arrangement location (signal separation position) of the directional coupler, the function as a sensor of the differential transmission system can be improved.

(Fifth Embodiment: Transmission Line Diagnosis Device)
In the fifth embodiment, a cable diagnostic device to which the measurement system described in the first to fourth embodiments is applied will be described. The cable diagnostic device diagnoses a failure of a pair of differential transmission cables including two transmission lines, such as a twisted pair line.

FIG. 11 is a diagram illustrating a configuration of the cable diagnostic device 50 according to the fifth embodiment. The cable diagnostic device 50 shown in FIG. 11 includes a board 51, a communication chip 52, a connector 53, a board 54, a connector 55, a communication chip 56, a divider 57, an amplifier 58, a detector 59, and an LED 60. , Is provided. The communication chip 52 and the connector 53 are provided on the substrate 51. The connector 55, the communication chip 56, the divider 57, the amplifier 58, the detector 59, and the LED 60 are provided on the substrate 54. Between the connector 53 and the connector 55,
The cable 70 to be inspected is connected. That is, the connector 53 and the connector 55 are attachment portions for attaching the cable 70 to be inspected.

  The communication chip 52 and the communication chip 56 transmit and receive, via the connectors 53 and 55 and the cable 70, a positive signal and a negative signal whose polarities are opposite to each other. The divider 57 combines the positive signal and the negative signal exchanged between the communication chip 52 and the communication chip 56 as they are (non-inverted) to generate an in-phase signal. The amplifier 58 amplifies the in-phase signal generated by the divider 57. The detector 59 measures the in-phase signal amplified by the amplifier 58, and determines that the cable is defective, and turns on the LED 60 when the measured value is larger than a certain value. The LED 60 is turned on when it is determined that the cable is defective. When a change such as a change in the physical shape or a change in the material of the line for transmitting the positive signal or the line for transmitting the negative signal of the cable 70 occurs, the transmission characteristic with respect to the transmission signal changes at the place where the change occurs (abnormal place). I do. A difference occurs in the amplitude and phase between the positive signal and the negative signal passing through the abnormal part of the line. When an amplitude difference and a phase difference appear between a positive signal and a negative signal transmitted through two transmission lines between the communication chip 52 and the communication chip 56, the amplified in-phase signal is measured by the detector 59. As a result, a slight change in the transmission line can be detected. Further, when the change is equal to or more than a certain value, the LED 60 can be turned on.

According to the cable diagnostic apparatus of the present embodiment, the in-phase signal synthesized without inverting the positive signal and the negative signal is one pair more than the differential signal obtained by synthesizing the positive signal and the inverted negative signal. , A large shift in the amplitude and phase between the transmission lines. Therefore, a change in the transmission line can be easily detected, and a minute error can be detected.
Further, the cable diagnostic device of the present embodiment is not limited to a method using a diagnostic signal as a positive signal and a negative signal, and can perform a diagnosis using an actual communication signal, so that it has high versatility.
When performing a diagnosis using a communication signal, a communication system using a differential transmission line (cable or the like) to be diagnosed can be used as it is, so that there is no need to separately construct a diagnostic system for inputting and outputting a diagnosis signal. The system can be simplified.

In the fifth embodiment, the divider 57, the amplifier 58,
Although the detector 59 and the LED 60 are provided, a diagnostic unit may be provided on the other substrate 51 as in the cable diagnostic device 50A shown in FIG. Since the error itself of the cable 70 to be diagnosed attenuates as it is transmitted, the more the detection unit (signal extraction position from the original signal) is closer to the error occurrence position, the more sensitive the diagnosis. Therefore, by providing a diagnostic unit on both substrates 51 and 54, the diagnostic accuracy is improved.

In the fifth embodiment, a twisted pair wire is used as the cable 70 to be diagnosed.
The diagnosis target is not limited to this. For example, as shown in FIG. 13, various transmission lines related to differential transmission, such as a differential line substrate 71, can be diagnosed.

(Sixth embodiment: transmission line diagnostic device)
In the cable diagnostic device 50 of the fifth embodiment shown in FIG. 11, when inspecting the shipment of twisted pair wires, it is usually highly likely that one of the twisted wires is defective (error), and both twisted wires are defective. It is unlikely that the degree of the defect will be exactly the same even if the defect has occurred. However, if the errors generated in the two transmission lines are coincidentally the same, and there is no phase difference, the diagnosis may be erroneous. Even in this case, a cable diagnostic device capable of detecting an error will be described in a sixth embodiment.

  FIG. 14 is a diagram illustrating a cable diagnostic device 80 according to the sixth embodiment. In the cable diagnostic device 80 of the present embodiment and the cable diagnostic device 50 of FIG. 11, the same reference numerals are given to the components that perform the same functions, and the duplicate description will be omitted. The cable diagnostic device 80 includes a common mode detection unit 81 and an amplitude change detection unit 82 provided on the board 54. The common mode detection section 81 includes a divider 57, an amplifier 58, and a detector 59. The amplitude change detection unit 82 includes a memory 83 and a determination unit CPU 84. The memory 83 stores data of cables having normal characteristics in advance. The determination unit CPU 84 detects and monitors the amplitude level itself of the signal being communicated. That is, the determination unit CPU 84 detects the amplitude change level of the differential signal obtained by inverting one of the positive signal and the negative signal transmitted through the cable 70 and synthesizing the inverted signal, and detects the level of the normal characteristic cable stored in the memory 83. Compare with data. If there is a difference between the two values that is equal to or greater than the threshold value (the threshold value for amplitude change), the determination unit CPU 84 determines that an error has occurred. The LED 85 is turned on when one of the detector 59 of the common mode detection unit 81 and the determination unit CPU 84 of the amplitude change detection unit 82 determines an error.

FIG. 15 is a diagram showing a flow of cable failure diagnosis in the cable diagnostic device 80 of the sixth embodiment. When the cable to be inspected is attached to the cable diagnosis device 80 and the cable diagnosis is started, the common mode detection unit 81 and the amplitude change detection unit 82 take out a positive signal and a negative signal (communication signal), respectively (step S1). ), And proceeds to the following processing. The common mode detector 81 determines the level of the in-phase signal detected by the detector 59 (step S2), and determines whether the level of the in-phase signal is equal to or less than the in-phase signal threshold (step S3). In step S3, if the level of the in-phase signal is not equal to or less than the in-phase signal threshold, the common mode detection unit 81 determines that the signal is “defective” and turns on the LED 85 (step S4). If the value is equal to or smaller than the threshold value, it is determined that the product is normal and the inspection is terminated. On the other hand, the amplitude change detection unit 82 determines the amplitude change of the differential signal (step S5), and determines whether the amplitude change of the differential signal is equal to or less than the amplitude change threshold (step S6). In step S6, if the amplitude change of the differential signal is not less than the amplitude change threshold value, the amplitude change detection unit 82 determines that the signal is "defective" and turns on the LED 85 (step S7), and the amplitude change threshold value. If the value is equal to or less than the value, it is determined to be normal and the inspection is terminated. The in-phase signal threshold and amplitude change threshold are
It is determined each time a diagnosis is made for each test object.

According to the cable diagnostic device 80 of the present embodiment, the two detection units, the common mode detection unit 81 and the amplitude change detection unit 82, are provided, and the determination as to whether the cable is defective is performed in parallel.
The following effects are obtained in addition to the effects of the fifth embodiment. That is, even when two transmission lines constituting the differential transmission line have the same level of failure at the same time, an error can be detected as an error by comparing the data with normal characteristic data. Therefore, the accuracy of diagnosis can be improved.

  In the sixth embodiment, the common mode detection unit 81, the amplitude change detection unit 82, and the LED 85, which are diagnostic units, are provided only on one of the substrates 54. However, as shown in FIG. May be provided. Since the error itself of the cable 70 to be diagnosed attenuates as it is transmitted, the more the detection unit (signal extraction position from the original signal) is closer to the error occurrence position, the more sensitive the diagnosis. Therefore, by providing a diagnostic unit on both substrates 51 and 54, the diagnostic accuracy is improved.

In the sixth embodiment, a twisted pair wire is used as the cable 70 to be diagnosed.
The diagnosis target is not limited to this. For example, as shown in FIG. 17, various transmission lines related to differential transmission, such as a differential line board 71, can be diagnosed.

(Seventh embodiment: liquid level detection device)
In the seventh embodiment, a liquid level detection device to which the measurement system described in the first to fourth embodiments is applied will be described.

FIG. 18 is a diagram illustrating a configuration of a liquid level detection device 90 according to the seventh embodiment. The liquid level detection device 90 shown in FIG. 18 includes a sensor unit and a determination unit 91. The sensor unit includes two substrates SU1 and SU2 having the same shape and provided with patterns PA1 and PA2 (first line and second line), respectively, in which a straight path is folded. The substrate SU1 is handled as a substrate for detecting a liquid level (hereinafter, also referred to as a liquid level detection substrate SU1). The substrate SU2 is
Treated as a reference board for correction (hereinafter, also referred to as reference board SU2).
The determination section 91 includes an oscillator 92, a balun 93, a common mode detection section 97 including a divider 94, an amplifier 95, and a detector 96, a CPU 98, and a display 99. The substrate SU1 is installed in the tank T to be measured, and the substrate SU2 is installed outside (near) the tank T.

  The oscillator 92 generates a signal for diagnosis. The balun 93 forms a differential signal from the output of the oscillator 92, that is, a positive signal and a negative signal whose polarities are opposite to each other. The positive signal and the negative signal output from the balun 93 are input to the liquid level detection substrate SU1 and the reference substrate SU2. The positive signal is input from the port 1 to the pattern PA2 on the reference substrate SU2, output from the port 3 and input to the divider 94. The negative signal is input from the port 2 to the pattern PA 1, output from the port 4, and input to the divider 94 on the liquid level detection substrate SU 1. The divider 94 combines the positive signal and the negative signal that have passed through the substrates SU1 and SU2 as they are (non-inverted) to generate an in-phase signal (common mode signal). The level of the in-phase signal corresponds to the liquid level in the tank T as described later. The amplifier 95 amplifies the in-phase signal generated by the divider 94. By amplifying the in-phase signal, a minute change in the liquid level can be easily detected. Detector 96 measures the in-phase signal amplified by amplifier 95. The CPU 98 calculates the liquid level from the measurement result of the in-phase signal. The display 99 displays the calculated liquid level.

FIG. 19 is a diagram illustrating a simulation model of the sensor unit. A three-dimensional electromagnetic field simulation model of the reference substrate SU2 and the liquid level detection substrate SU1 shown in FIG. 19 was created, and the transmission characteristics when the liquid level was changed were analyzed. The sensor unit is a fr4 substrate having a Cu pattern of 1 mm width. A liquid having a dielectric constant of 3 assuming gasoline was set as the liquid to be measured. The transmission characteristics obtained by the electromagnetic field analysis using the simulation model were taken into the sensor characteristics of a circuit simulator model in which only the common mode detection unit 97 was taken out, and the common mode voltage change with respect to the liquid level change was analyzed. The signal for detection is
A differential sine wave of Vp-p100mV at 100 MHz was used. FIG. 20 shows the simulation result.

  FIG. 20 is a diagram showing a simulation result using the model shown in FIG. FIG. 20 shows a change in the common mode voltage when the liquid level is changed to 0, 20, 40, 60, 80, and 100 mm. From FIG. 20, it can be confirmed that the common mode voltage changes linearly with the change in the liquid level. If this simulation result is stored in advance as a table, the CPU 98 can easily calculate the liquid level from the measurement result of the detector 96 by referring to the table.

  According to the liquid level detection device 90 of the present embodiment, the substrate SU1 is set in the tank T to be measured for detecting the liquid level, and the substrate SU2 is used as a reference for correction. The difference according to the plane level appears as the level of the in-phase signal. That is, since a phase change, not an amplitude change of the positive signal and the negative signal, can be detected, the liquid level can be detected with high accuracy. Further, since the sensor is not a conventional capacitance detection type sensor, a linear pattern is sufficient, and a comb-shaped pattern for providing a capacitance to the substrate of the sensor unit is not required, so that the sensor shape can be made slim.

  In the seventh embodiment, the substrates SU1 and SU2 having the patterns PA1 and PA2 obtained by folding the straight path are used as the sensor unit. However, the twisted pair lines shown in FIG. 21A and the strip lines shown in FIG. 21B are used. May be used. Alternatively, any medium that can transmit signals, such as a flat line or an FPC, can be used as the sensor unit.

In the seventh embodiment, the substrates SU1 and SU2 having the same shape are used as the liquid level detection substrate and the reference substrate. However, the reference substrate may be one that can transmit signals at the same speed and the same time as the liquid level detection substrate. I just need. Therefore, even if they are not the same line shape, FIG.
By applying a high-permittivity substrate shown in (a) or a meander line shown in FIG. 22 (b) so that the pattern and the electrical length of the liquid level detection substrate are equal to each other, the reference substrate can be used. Can be downsized.

(Eighth embodiment: liquid level detection device)
In the liquid level detection device 90 of the seventh embodiment shown in FIG. 18, the U-shaped reciprocating path portion of the line of the sensor unit is used for detecting the liquid level (disposed in the liquid). In addition, the width (width) in the short direction is required for the round-trip line, which takes up space. Further, in the liquid level detection device 90 of the seventh embodiment, when the solution to be detected is changed, for example, the dielectric constant is lowered, the change from the reference becomes small, and the common (in-phase signal) output Even if the value decreases and detection becomes difficult, adjustment may be difficult. In the eighth embodiment, a description will be given of a liquid level detecting device capable of solving these problems.

  The liquid level detecting device 90 of the eighth embodiment is different from the liquid level detecting device 90 of the seventh embodiment shown in FIG. 18 in that two substrates SU1A and SU2A having the same shape are provided instead of the substrates SU1 and SU2. As shown in FIG. 25, the substrates SU1A and SU2A are obtained by changing the patterns PA1 and PA2 of the sensor unit to the patterns PA1A and PA2A in the substrates SU1 and SU2, respectively. Other configurations of the liquid level detection device 90 of the eighth embodiment are the same as those described above, and thus redundant description will be omitted.

  FIG. 25 is a diagram illustrating a simulation model of a sensor unit in the liquid level detection device according to the eighth embodiment. In the patterns PA1A and PA2A of the present embodiment, open stubs ST1 and ST2 are provided on the input / output passing lines L1 (lines from port1 to port3) and L2 (lines from port2 to port4) on the substrates SUA1 and SUA2, respectively. It has a shape. In the present embodiment, the input / output passing lines L1 and L2 are not used for sensing the liquid level, but detect the liquid level using the open stubs ST1 and ST2.

  FIG. 26 is a diagram illustrating a measurement principle of the liquid level detecting device according to the eighth embodiment, and illustrates a change in frequency characteristics in the open stubs ST1 and ST2. When a high-frequency signal is transmitted to a line including an open stub, the high-frequency signal is characterized in that it behaves electrically short at a frequency of a wavelength λ whose stub length is λ / 4 (FIG. 26A). At this time, the signal becomes an image flowing in the stub direction, the transmission characteristic (S21 parameter) of the input signal deteriorates, and a valley characteristic is exhibited as shown in FIG. Here, when the stub portion is immersed in the solution for liquid level detection, the stub length becomes electrically long according to the length of the immersion in the solution, so that the frequency at which the transmission characteristics deteriorate is low. It moves to the frequency side (FIG. 26 (b)). That is, a change in the pass characteristic when detecting at a certain specific frequency is synonymous with a change in the signal level and a change in the phase. The surface level can be detected.

  FIG. 27 is a diagram showing a frequency characteristic result with respect to a liquid level change by a simulation using the model shown in FIG. 25, and shows a pass characteristic result when the liquid level is changed in a range of 1 to 100 mm. From FIG. 27, it can be seen that the frequency characteristic shifts to the lower frequency side as the liquid level increases.

  FIG. 28 is a diagram showing a simulation result using the model shown in FIG. 25. The sensor characteristics showing the result of FIG. 27 are inserted into a common mode detection circuit, and the common mode voltage value with respect to the liquid level is plotted in a graph. This is the result. From FIG. 28, it can be seen that the voltage value increases linearly as the liquid level increases, and the liquid level can be detected from the voltage value. The liquid level detection device 90 of the present embodiment has a feature that the sensitivity can be changed by changing the frequency to be sensed. FIG. 28 shows the detection result when a 100 MHz signal is input. From the result shown in FIG. 27, since the change in the frequency characteristic becomes large at 100 MHz or higher, an improvement in the detection sensitivity is assumed. Therefore, sensitivity adjustment can be performed even when the solution whose liquid level is to be detected is changed to one having a different dielectric constant.

  The liquid level detection device 90 of the present embodiment generates a signal difference corresponding to a change in the liquid surface position as an in-phase signal using the open stubs ST1 and ST2 provided on the input / output lines L1 and L2, Detect position. With this configuration, in addition to the effects of the seventh embodiment, compact and highly accurate liquid level measurement can be performed. That is, since the liquid level can be detected only by the open stubs ST1 and ST2 (one line), the sensor element can be made slim. Therefore, it is possible to detect the liquid level of a calorimeter or the like. In addition, the sensitivity of the sensor can be improved by adjusting the frequency for detection for a liquid level detection target such as a solution having a low dielectric constant, which has a small change from the reference and makes it difficult to detect an in-phase signal, The sensor level can be detected.

  In the eighth embodiment, the substrates SU1A and SU2A having the patterns PA2A and PA1A including the open stubs ST1 and ST2 on a straight path are used as the sensor unit, but the single line shown in FIG. 29A or the single line shown in FIG. ) May be used. Alternatively, any medium that can transmit signals, such as a twisted pair wire, a flat wire, and an FPC, can be used as the sensor unit.

  In the eighth embodiment, the substrates SU1A and SU2A having the same shape are used as the liquid level detection substrate and the reference substrate. However, the reference substrate may be one that can transmit signals at the same speed and the same time as the liquid level detection substrate. I just need. Therefore, even if the line shape is not the same, the pattern and the electrical length of the liquid level detection substrate are equal to each other by applying the high dielectric substrate shown in FIG. 30A or the meander line shown in FIG. With such a design, the size of the reference substrate can be reduced.

(Ninth embodiment: displacement detection device)
As a displacement sensor that performs position detection, for example, a sensor that detects an induced voltage due to an eddy current generated in a metal plate of an object to be measured by a receiving coil and outputs position information through a comparison between the induced voltage and information stored in a memory. (See Patent Document 9). In this displacement sensor, variations in measured values due to changes in the surrounding environment such as temperature changes are assumed, and there is a problem in measurement accuracy. Further, in this displacement sensor, the measurement sensitivity may vary depending on the size of the measurement target, the sensor distance, and the like, but it is difficult to adjust the sensitivity. In the ninth embodiment, a non-contact displacement detection device that can solve these problems will be described. The non-contact displacement detection device according to the ninth embodiment is a displacement detection device to which the measurement system described in the first to fourth embodiments is applied.

  FIG. 31 is a diagram illustrating the configuration of the displacement detection device 200 according to the ninth embodiment. The displacement detection device 200 of FIG. 31 is obtained by changing the sensor unit in the liquid level detection device 90 of FIG. The same reference numerals are given to the components that perform the same functions in the displacement detection device 200 in FIG. 31 and the liquid level detection device 90 in FIG. 18, and overlapping descriptions will be omitted. The displacement detection device 200 illustrated in FIG. 31 includes a sensor unit and a determination unit 91. The sensor unit in FIG. 31 includes a reference sensor 201 and a displacement sensor 202 to which a one and a half loop coil 203 formed of a substrate is applied. The CPU 98 calculates the displacement level from the measurement result of the in-phase signal, and the calculated displacement level is displayed on the display 99. That is, in the ninth embodiment, a signal difference according to a position change when a metal block as a device under test (DUT) approaches the displacement sensor 202 is generated as an in-phase signal, and the position is detected without contact. be able to.

  FIG. 32 is a diagram illustrating a simulation model of the sensor unit in the displacement detection device 200 according to the ninth embodiment. FIG. 33 is a diagram illustrating the measurement principle of the displacement detection device according to the ninth embodiment. As shown in FIG. 32A, a one and a half loop coil 203 is used as a sensor model. The frequency characteristic (S21 characteristic) when the metal block 204 is placed close to the displacement sensor 202 at the frequency at which radiation is generated and the distance D between the displacement sensor 202 and the metal block 204 is changed is analyzed. As shown in FIG. 33, a sensor having the same shape is prepared as a simulation model, and one of the sensors is used as a reference sensor 201 and the other is used as a displacement sensor 202. With respect to the reference sensor 201, a difference in coil characteristics occurs according to the distance D between the displacement sensor 202 and the metal block 204. The displacement detection device 200 generates and detects this difference as an in-phase signal. As the metal block 204 approaches the displacement sensor 202, the magnetic field generated from the coil (the one-and-a-half loop coil 203) interlinks, and an eddy current is generated in the metal block 204. This generated magnetic field affects the coil inductance characteristics.

  FIG. 34 is a diagram illustrating a change in frequency characteristics (S21 characteristics) according to a change in the distance of the metal block 204 illustrated in FIG. 33. According to FIG. 34, there is a tendency that the S21 characteristic is improved as the metal block 204 approaches the displacement sensor 202. It is considered that this is because the impedance has changed in the matching direction due to the change in the inductance of the coil. According to FIG. 34, the S21 characteristic linearly changes in accordance with the distance D between the displacement sensor 202 and the metal block 204, indicating that the position can be detected.

  FIG. 35 is a diagram showing a simulation result using the model shown in FIG. 32. The simulation is performed by incorporating the electromagnetic field analysis results shown in FIG. 34 into the sensor units (the reference sensor 201 and the displacement sensor 202) shown in FIG. The result of performing is shown. As a detection signal, a differential sine wave of 900 MHz and Vp-p of 100 mV was used. The detection frequency is set to 900 MHz because the difference in the frequency characteristic with respect to the change in the distance D linearly changes in the result of FIG. As shown in FIG. 35, the common mode voltage when the distance D is made closer by 10 mm increases linearly. The voltage is generated when the distance D is 0 because a voltage that changes depending on the presence or absence of the metal block 204 is generated as compared to the reference sensor 201 where the metal block 204 is not placed.

  According to the displacement detection device 200 of the present embodiment, since the displacement is detected by comparing with the reference, the influence of error factors such as the external environment is reduced, and accurate measurement can be performed. Further, by adjusting the detection frequency, the sensitivity of the sensor can be adjusted without changing the sensor shape. Furthermore, since an object can be detected without contact, a wide range of applications such as a human sensor and a pet sensor can be performed.

  In the ninth embodiment, a one-and-a-half-turn loop coil 203 is used as the sensor unit. However, a solenoid coil may be applied as shown in FIG. By using a solenoid coil, a displacement sensor having high sensitivity in the central axis direction can be realized. Further, as shown in FIG. 36B, by replacing the reference sensor 201 with a chip component such as a capacitor, the sensor can be made slim.

(Tenth embodiment: pressure detector)
As a pressure sensor that detects pressure, for example, there is a pressure sensor that includes a piezoelectric vibrator that is fixed to a diaphragm and generates a stress according to the deflection thereof and an excitation electrode (see Patent Document 12). In this pressure sensor, the oscillation frequency of the piezoelectric vibrator changes due to the stress applied to the diaphragm. Therefore, the pressure sensor derives a pressure value according to the value of this frequency. This pressure sensor has a complicated structure that uses a piezoelectric vibrator and is sandwiched between electrodes.It is difficult to obtain a reasonable result while maintaining sensitivity in consideration of the influence of the use environment and deterioration due to use time. is assumed. In addition, it is difficult to adjust the sensitivity of the pressure sensor to variations in the target of pressure detection, environmental factors and the like easily. In the tenth embodiment, a pressure detection device that can solve these problems will be described. The pressure detection device according to the tenth embodiment is a pressure detection device to which the measurement system described in the first to fourth embodiments is applied.

  FIG. 37 is a diagram illustrating a configuration of the pressure detection device 210 according to the tenth embodiment. The pressure detection device 210 in FIG. 37 is obtained by changing the sensor unit in the liquid level detection device 90 in FIG. Components that perform the same functions in the pressure detecting device 210 in FIG. 37 and the liquid level detecting device 90 in FIG. 18 are denoted by the same reference numerals, and redundant description will be omitted. The pressure detection device 210 illustrated in FIG. 37 includes a sensor unit and a determination unit 91. 37 has a reference sensor 211 and a pressure sensor 212. The CPU 98 calculates levels such as pressure and stress from the measurement result of the in-phase signal, and the calculated levels are displayed on the display 99. That is, in the tenth embodiment, it is possible to detect a pressure change by generating a difference between signals according to a change in pressure applied to the pressure sensor as an in-phase signal.

  FIG. 38 is a diagram illustrating a simulation model of a sensor unit in the pressure detection device 210 according to the tenth embodiment, and also illustrates a change parameter due to pressurization. Here, as an example of the sensor shape, an example of a sensor 213 covered with a diaphragm with electrode plates having a diameter of 20 mm facing each other at an interval of 1 mm will be described. In the simulation, a frequency characteristic (S21 characteristic) in a case where a gap between the electrode plates is reduced by 0.1 mm by applying pressure to the sensor 213 is analyzed.

  FIG. 39 is a diagram showing a change in frequency characteristics due to a change in the electrode plate interval (pressure change) shown in FIG. Since the capacitance increases as the distance between the electrode plates decreases, the cutoff frequency of the passing signal moves to the lower frequency side, and the frequency characteristic of S21 changes. According to FIG. 39, as the distance approaches 0.1 mm, the frequency shifts to a lower frequency at equal intervals in frequency.

  FIG. 40 is a diagram illustrating a simulation model of a sensor unit in the pressure detection device 210 according to the tenth embodiment. A sensor having the same shape is prepared, and one is used as a reference sensor 211 and the other is used as a pressure sensor 212. As compared with the reference sensor 211, the pressure sensor 212 changes the electrode plate interval due to the pressure, and the capacitance changes in accordance with the change, so that the difference in the passage characteristics shown in FIG. 39 occurs. The pressure detector 210 generates and detects this difference as an in-phase signal.

  FIG. 41 is a diagram illustrating a simulation result using the models illustrated in FIGS. 38 and 40. The sensor unit (the reference sensor 211 and the pressure sensor 212) illustrated in FIG. 37 is obtained by the electromagnetic field analysis illustrated in FIG. A result obtained by simulating the obtained S21 characteristic is shown. In this simulation, the change in the common mode voltage with respect to the change in the electrode plate interval of the sensor, which was regarded as the pressure change, was analyzed. As a signal for detection, a differential sine wave of 100 mV at 100 MHz was used. The detection frequency was set to 100 MHz because the difference in the frequency characteristic with respect to the change in the electrode plate interval was clearly visible in the result of FIG. As shown in FIG. 41, the common mode voltage when the electrode plate interval is approached by 0.1 mm increases linearly.

  According to the pressure detection device 210 of the present embodiment, highly sensitive sensing can be performed by the common mode detection method. Further, since the pressure is detected by comparison with the reference, the influence of error factors such as the external environment is reduced, and accurate measurement can be performed. Further, by adjusting the detection frequency, the sensitivity of the sensor can be adjusted without changing the sensor shape. Therefore, it is possible to detect a change in pressure in the tire or the battery pack and a change in stress applied to the seat belt.

  In the tenth embodiment, the sensors 213 are used for the reference sensor 211 and the pressure sensor 212 as the sensor units, but both may be integrated. As shown in FIG. 42, by installing a reference sensor immediately below the pressure sensor and integrating them, it is possible to make the sensor slim. Also, as shown in FIG. 43, by replacing the reference sensor 211 with a chip component such as a capacitor, the sensor can be made slimmer.

(Eleventh embodiment: acceleration detection device)
As an acceleration sensor that detects acceleration, for example, there is a capacitance type acceleration sensor that measures acceleration based on a change in capacitance between a movable electrode and a fixed electrode (see Patent Document 16). In this acceleration sensor, a charge / voltage conversion circuit including a plurality of operational amplifiers, resistors, and capacitors converts charges accumulated between a fixed electrode and a movable electrode into a voltage signal and outputs the voltage signal. This acceleration sensor captures a potential variation difference between a fixed electrode and a movable electrode. However, the acceleration sensor is apt to cause an error that a difference between outputs of two operational amplifiers for detecting capacitance is detected by a next operational amplifier. In addition, this configuration is concerned with real-time sensing and sensitivity. In addition, the sensitivity of this acceleration sensor cannot be adjusted after the detection system is manufactured. In the eleventh embodiment, an acceleration detection device that can solve these problems will be described. The acceleration detection device according to the tenth embodiment is an acceleration detection device to which the measurement system described in the first to fourth embodiments is applied.

  FIG. 44 is a diagram illustrating a configuration of the acceleration detection device 220 according to the eleventh embodiment. FIG. 45 is a diagram illustrating a configuration of the sensor unit 221 in the acceleration detection device 220 according to the eleventh embodiment. The acceleration detection device 220 shown in FIG. 44 is obtained by changing the sensor unit and a part of the determination unit 91 in the liquid level detection device 90 of FIG. Components having the same functions performed by the acceleration detecting device 220 in FIG. 44 and the liquid level detecting device 90 in FIG. 18 are denoted by the same reference numerals, and redundant description will be omitted. The acceleration detection device 220 illustrated in FIG. 44 includes a sensor unit 221 and a determination unit 91A. The determining unit 91A is obtained by removing the divider 94 from the determining unit 91 shown in FIG.

  The sensor unit 221 is a uniaxial acceleration sensor, and includes a movable electrode 222, a pair of fixed electrodes 223, a support 224, and four springs 225, as shown in FIG. The movable electrode 222 has a box shape and is arranged at the center of the support 224. Each of the pair of fixed electrodes 223 has a box shape, and is disposed at both ends of the movable electrode 222 so as to be separated from the movable electrode 222 by a predetermined distance. The support 224 has a bottom plate 224A and a pair of side plates 224B provided upright at both ends of the bottom plate 224A, and has a U-shape in a cross-sectional view along a vertical plane. Each fixed electrode 223 is fixed to each side plate 224B, and two springs 225 having one end fixed to the side plate 224B and the other end connected to the movable electrode 222 are elastically provided below the fixed electrode 223. That is, the movable electrode 222 is supported by the spring 225 fixed to the support 224. When the movable electrode 222 moves along with the acceleration, a change in capacitance between the electrodes (between the fixed electrode 223 and the movable electrode 222) at that time is converted into a movement amount, and the acceleration is further reduced by the spring constant and the mass of the movable electrode. Is calculated.

  In the acceleration detection device 220 shown in FIG. 44, a differential signal (positive signal and negative signal) is generated by the balun 93 from the diagnostic signal generated by the oscillator 92, and is input to the pair of fixed electrodes 223, respectively. Thereafter, the signal passed according to the capacitance between the electrodes is combined through the movable electrode 222, that is, a signal difference corresponding to a change in vibration of the movable electrode 222 is generated as an in-phase signal, and is input to the amplifier 95. Is done. The amplifier 95 amplifies the in-phase signal, that is, amplifies the difference signal generated from the amplitude and phase difference between the two signals passed according to the capacitance between the electrodes. The detector 96 measures the in-phase signal amplified by the amplifier 95 and outputs the signal as an analysis signal. The CPU 98 calculates the acceleration from the measurement result of the in-phase signal. The display 99 displays the calculated acceleration.

  FIG. 46 is a diagram showing a simulation model of the sensor unit 221 shown in FIG. In this model, a pair of fixed electrodes 223 are installed at a distance of 1 mm from the center movable electrode 222. The differential signal from the balun 93 shown in FIG. 44 is input to port 1 and port 2, and the signal from the movable electrode 222 after passing is output from port 3. That is, the positive signal and the negative signal output from the balun 93 are input to the pair of fixed electrodes 223 from port1 and port2, respectively. Then, an in-phase signal (common mode signal) generated by synthesizing both the positive signal and the negative signal that have passed between the electrodes as they are (non-inverted) is output from port3. In this model, the frequency characteristics in a situation where the movable electrode 222 is moved to the port 1 side by 0.1 mm at the time of acceleration are analyzed.

  FIG. 47 is a diagram showing a simulation result (frequency characteristic change) using the model shown in FIG. FIG. 47 shows characteristics picked up when the movable electrode 222 moves to the port 1 side by 0.1 mm and 0.4 mm. There is a tendency that the capacitance increases as the movable electrode 222 (electrode plate) moves closer to the one fixed electrode 223, so that the cutoff frequency of the passing signal moves to the lower frequency side. At this time, since the interval between the fixed electrode 223 and the movable electrode 222 on the opposite side increases, the cutoff frequency of the passing signal moves to the high frequency side. Therefore, it is assumed that the larger the moving distance of the electrode plate is, the larger the output of the combined signal appearing in port 3 is. In FIG. 47, w represents the moving distance of the movable electrode 222 (electrode), for example, w01 indicates that the electrode has moved by 0.1 mm. Looking at the band expanded to the right in FIG. 47, it can be seen that the frequency characteristics change at equal intervals. Looking at the difference between the S31 parameter (w01_s31) and the S32 parameter (w04_S32) between the movement of 0.1 mm and the movement of 0.4 mm, the difference of about 0.4 mm is about three times larger than the case of 0.1 mm. You can see that there is.

  FIG. 48 is a diagram showing a simulation result (output voltage change) using the model shown in FIG. As a signal for detection, a differential sine wave of Vp-p100mV at 1 GHz was used. The detection frequency was set to 1 GHz because, in the results of FIG. 47, the difference in the frequency characteristics with respect to the change in the electrode plate interval was clearly seen as a tendency.

  According to the acceleration detecting device 220 of the present embodiment, since the high-frequency signal is directly applied to the electrode plate and the difference of the phase change as well as the amplitude change is simultaneously taken and output as the common mode voltage, high-accuracy measurement can be performed. The system becomes simple. Further, as shown in the simulation result of FIG. 47, the acceleration detection device 220 exhibits various sensitivities depending on the frequency with respect to the movement of the movable electrode 222 (electrode plate). By adjusting the detection frequency to be performed, it is possible to perform measurement at a frequency with good sensitivity or at multiple frequencies.

  In the eleventh embodiment, the example in which the sensor unit 221 is a uniaxial acceleration sensor has been described. However, as shown in FIG. 49, the movable electrode 222 is interposed in a direction orthogonal to the arrangement direction of the pair of fixed electrodes 223. By providing the pair of fixed electrodes 223A, a two-axis compatible acceleration sensor (acceleration detecting device 220A) can be obtained. Also, as shown in FIG. 50, a signal is input to the movable electrode 222, and the signals from the pair of fixed electrodes 223 are combined by the divider 94C to obtain a difference between the two signals as a common mode signal. The device 220B can also be used. As shown in FIGS. 49 and 50, by synthesizing the waveforms in the sensor units 91B and 91C with the dividers 94A to 94C, it is expected that the accuracy in deriving the signal difference is improved.

(Twelfth embodiment: linear sensor device)
In the field of construction and the field of aircraft materials, it has been proposed to perform deterioration diagnosis using an optical fiber sensor. As shown in FIG. 50, the optical fiber sensor 120 includes, at both ends of an optical fiber 121, an E / O converter 122 that converts an electric signal into an optical signal and an O / E converter 123 that converts an optical signal into an electric signal. Are provided respectively. The optical fiber sensor has features such as small size, light weight, long life, and no power supply to the sensor. In particular, a distributed optical fiber sensor in which the optical fiber itself functions as a sensor can obtain a strain distribution that is positionally continuous along the entire length of the optical fiber. There are several types of scattered light generated in an optical fiber, of which Brillouin scattered light is a scattering phenomenon caused by acoustic waves generated and propagated by incident light, and the incident light undergoes a Doppler shift and varies according to the frequency of the acoustic wave. The wavelength shifts. This scattering occurs everywhere in the optical fiber, and the wavelength of the scattered light depends on the distortion of the generating position. Strain information can be obtained at all positions along the optical fiber. Many applications of the sensing technology using “natural Brillouin scattered light” due to incident light from one end of an optical fiber have been attempted in the field of architecture. On the other hand, sensing technology using “stimulated Brillouin scattered light” by making two lights face each other from both ends of an optical fiber is also actively developed, and its strong light intensity has features such as high spatial resolution.

  However, in the optical fiber sensor, an electric signal is converted into an optical signal (E / O conversion), and the optical signal is converted again into an electric signal (O / E conversion). Therefore, the energy conversion efficiency is low. In addition, O / E conversion devices are expensive and cost reduction is difficult. On the other hand, the optical fiber sensor has a functional merit of a linear sensor that can perform deterioration diagnosis not by dots but by lines. Thus, there has been a need for a linear sensor technology that compensates for the disadvantages of optical fiber sensors.

  In the twelfth embodiment, a linear sensor that compensates for the disadvantage of the optical fiber sensor will be described. The linear sensor device of the twelfth embodiment is an application of the measurement system described in the first to fourth embodiments. That is, in the measurement system 1 shown in FIG. 1, by using a linear sensor for the transmission line between the communication devices A and B (the differential transmission line 10), it is possible to capture a point where an abnormality has occurred by a point. .

  FIG. 52 is a diagram illustrating an example of the arrangement of the linear sensors according to the twelfth embodiment, and illustrates an example of the arrangement as the linear sensors distributed two-dimensionally. The linear sensor 10A shown in FIG. 52A has two lines 10A-1 and 10A-2 having the same line length arranged in parallel. This arrangement is suitable when a difference is expected even if the distance between the two lines is narrow. The linear sensor 10B shown in FIG. 52 (b) is configured such that two lines 10B-1 and 10B-2 having the same line length are arranged in parallel to complement each other. According to this arrangement, the distance between the two lines can be increased, and the difference can be easily recognized. Also, unlike the case of FIG. 52 (c), both can be used as sensors. The linear sensor 10C shown in FIG. 52C has one line 10C-1 of two lines 10C-1 and 10C-2 having the same line length for measurement, and the other line 10C-2 for reference. And According to this arrangement, the difference between the lines is maximized, which is suitable for precision measurement.

  According to the present embodiment, in the measurement system described in the first to fourth embodiments, the differential transmission path 10 is configured as the linear sensors 10A to 10C, so that a line that can be constituted only by an electric signal without using an optical fiber. A shape sensor device can be constructed. According to this linear sensor, although the loss of the transmission line itself is larger than that of the optical fiber, the energy utilization efficiency is high due to the loss reduction during E / O and O / E conversion. Therefore, it is considered that the optical fiber is excellent for long-distance use, and the linear sensor of the present embodiment is excellent for short-distance use. It is assumed that the cost comparison is the same.

Here, the features of the measurement method, the transmission line diagnosis device, the detection device, and the linear sensor device according to the above-described embodiment of the present invention will be briefly summarized and listed below in [1] to [16].
[1] In a pair of differential transmission lines (10) including a first transmission line transmitting a first signal and a second transmission line transmitting a second signal having a phase opposite to the first signal, the first transmission line And the second signal transmitted through the second transmission line are combined to generate an in-phase signal (combiner 5),
Measuring the generated in-phase signal (measuring device C);
A measuring method characterized in that:
[2] amplifying the generated in-phase signal (low noise amplifier 17);
Measuring the amplified in-phase signal;
The measurement method according to the above [1], wherein:
[3] measuring the generated in-phase signal after attenuating a signal in a frequency band higher than a target frequency band (filter 16),
The measuring method according to the above [1] or [2], wherein:
[4] The first signal transmitted through the first transmission line and the second signal transmitted through the second transmission line are extracted by a directional coupler and combined.
The measuring method according to any one of the above [1] to [3], wherein:
[5] A mounting part (a cable 70) to which a pair of differential transmission lines (cable 70) including a first transmission line for transmitting a first signal and a second transmission line for transmitting a second signal having a phase opposite to the first signal is mounted. Connectors 53, 55);
A first communication unit (communication chip 52) that transmits the first signal and the first signal to the differential transmission path via the attachment unit;
A second communication unit (communication chip 53) that receives the first signal and the second signal from the differential transmission path via the attachment unit;
A signal combiner (divider 57) that extracts and combines the first signal and the second signal received by the second communication unit to generate an in-phase signal;
A detector (detector 59) for detecting the generated in-phase signal;
A determination unit (detector 59) that determines that an error has occurred when the detected magnitude of the in-phase signal is equal to or greater than a threshold value;
A diagnostic device comprising:
[6] An amplifier (amplifier 58) for amplifying the in-phase signal generated by the signal synthesizer,
The detector detects the in-phase signal amplified by the amplifier,
The diagnostic device according to the above [5], wherein:
[7] The determination unit extracts the first signal and the second signal received by the second communication unit, and compares the first signal and the second signal with data of normal characteristics stored in a memory to determine whether the error has occurred. to decide,
The diagnostic device according to the above [5] or [6], wherein:
[8] a first line (pattern PA1) to which a first signal is input;
A second line (pattern PA2) to which a second signal having a phase opposite to the first signal is input;
A combining unit (divider 94) that combines the first signal passing through the first line and the second signal passing through the second line to generate an in-phase signal;
A detection unit (detector 96) for detecting the voltage of the generated in-phase signal;
A calculating unit (CPU 98) for calculating a liquid level from the detected voltage;
(Liquid level detector 90).
[9] an amplifying unit (amplifier 95) for amplifying the generated in-phase signal,
The detection unit detects a voltage of the amplified in-phase signal,
The detection device according to the above [8], wherein:
[10] The calculation unit calculates the liquid level with reference to a table indicating a correspondence between the liquid level and the voltage.
The detection device according to the above [8] or [9], wherein:
[11] The first line has a first open stub (ST1),
The second line has a second open stub (ST2),
The combining unit, the first signal that has passed through the first open stub, and the second signal that has passed through the second open stub, and combines the in-phase signal,
The detection device according to any one of [8] to [10], wherein:
[12] a first sensor (reference sensors 201 and 211) to which the first signal is input;
A second sensor (displacement sensor 202, pressure sensor 212) to which a second signal having a phase opposite to the first signal is input;
A combining unit (divider 94) that combines the first signal that has passed through the first sensor and the second signal that has passed through the second sensor to generate an in-phase signal;
A detection unit (detector 96) for detecting the voltage of the generated in-phase signal;
A calculating unit (CPU 98) for calculating a displacement level or pressure from the detected voltage;
(Displacement detection device 200, pressure detection device 210).
[13] At least one of the first sensor and the second sensor includes a loop coil (203),
The calculation unit calculates a distance between the loop coil and the measured object as the displacement level,
The detection device (displacement detection device 200) according to the above [12], wherein:
[14] Each of the first sensor and the second sensor includes a pair of electrode plates spaced apart from each other,
The calculation unit calculates a distance between the pair of electrode plates that changes due to pressure as the pressure,
The detection device (pressure detection device 210) according to the above [12], wherein:
[15] a movable electrode (222);
First and second fixed electrodes (223) that are arranged apart from the movable electrode and face each other across the movable electrode;
The first signal that has passed between the movable electrode and the first fixed electrode, and the second signal that has passed between the movable electrode and the second fixed electrode, the voltage of the in-phase signal synthesized A detection unit (detector 96) for detecting;
A calculating unit (CPU 98) for calculating an acceleration from the detected voltage;
A detection device (acceleration detection device 220), comprising:
[16] Two communication devices (A, B),
First and second transmission lines (10A, 10B, 10C) having the same line length, disposed between the two communication devices;
A combiner (5) that combines the first signal that has passed through the first transmission path and the second signal that has passed through the second transmission path to generate an in-phase signal;
A measuring instrument (C) for measuring the generated in-phase signal,
A linear sensor device comprising:

DESCRIPTION OF SYMBOLS 1 Measurement system 5 Synthesizer 10 Differential transmission path 10A-10C Linear sensor 11 Measurement system 12 Communication board 13 Communication board 13a Communication chip 15 Power adder 16 Filter 17 Low noise amplifier 18 Detector 19 Monitoring device 20 Differential cable 21 Measurement system 50 Cable diagnostic device 50A Cable diagnostic device 51 Board 52 Communication chip 53 Communication chip 53 Connector 54 Board 55 Connector 56 Communication chip 57 Divider 58 Amplifier 59 Detector 60 LED
70 Cable 71 Board 80 Cable Diagnostic Device 81 Common Mode Detector 82 Amplitude Change Detector 83 Memory 84 Judgment Unit CPU
85 LED
90 Liquid Level Detection Device 91 Judgment Unit 92 Oscillator 93 Balun 94 Divider 95 Amplifier 96 Detector 97 Common Mode Detection Unit 98 CPU
99 display 100 measurement system 101 synthesizer 110 differential transmission cable 110 signal line (differential transmission cable)
200 Displacement detection device 201, 211 Reference sensor 202 Displacement sensor 212 Pressure sensor 220 Acceleration detection device 222 Movable electrode 223, 223A Fixed electrode A Communication device B Communication device C Measurement device CB Combiner D Driver R Receiver ST1, ST2 Open stub SU1, SU1A Liquid level detection board SU2, SU2A Reference board T tank

Claims (16)

In a pair of differential transmission lines consisting of a first transmission line transmitting a first signal and a second transmission line transmitting a second signal having a phase opposite to the first signal, the second transmission line transmitted through the first transmission line One signal and the second signal transmitted through the second transmission line are combined to generate an in-phase signal,
Measuring the generated in-phase signal,
A measuring method characterized in that: Amplifying the generated in-phase signal,
Measuring the amplified in-phase signal;
The method according to claim 1, wherein: The generated in-phase signal is measured after attenuating a signal in a frequency band higher than a target frequency band,
The measurement method according to claim 1 or 2, wherein: The first signal transmitted through the first transmission line and the second signal transmitted through the second transmission line are extracted by a directional coupler, and are combined.
The measuring method according to any one of claims 1 to 3, wherein: Attachment part to which a pair of differential transmission lines consisting of a first transmission line transmitting a first signal and a second transmission line transmitting a second signal having a phase opposite to the first signal is attached,
Via the mounting portion, a first communication unit that transmits the first signal and the first signal to the differential transmission path,
Through the mounting portion, a second communication unit that receives the first signal and the second signal from the differential transmission path,
A signal synthesizer that extracts the first signal and the second signal received by the second communication unit and combines them to generate an in-phase signal,
A detector for detecting the generated in-phase signal;
A determining unit that determines that an error has occurred when the detected magnitude of the in-phase signal is equal to or greater than a threshold,
A diagnostic device comprising: An amplifier that amplifies the in-phase signal generated by the signal synthesizer,
The detector detects the in-phase signal amplified by the amplifier,
The diagnostic device according to claim 5, wherein: The determination unit extracts the first signal and the second signal received by the second communication unit,
By comparing with the data of the normal characteristics stored in the memory, it is determined whether or not the error,
The diagnostic device according to claim 5, wherein: A first line to which a first signal is input;
A second line to which a second signal having a phase opposite to that of the first signal is input;
A combining unit that combines the first signal that has passed through the first line and the second signal that has passed through the second line to generate an in-phase signal,
A detection unit that detects a voltage of the generated common-mode signal,
A calculating unit for calculating a liquid level from the detected voltage,
A detection device comprising: An amplification unit that amplifies the generated in-phase signal,
The detection unit detects a voltage of the amplified in-phase signal,
The detection device according to claim 8, wherein: The calculation unit refers to a table indicating a correspondence between the liquid level and the voltage, and calculates the liquid level.
The detection device according to claim 8 or 9, wherein: The first line has a first open stub,
The second line has a second open stub,
The combining unit, the first signal that has passed through the first open stub, and the second signal that has passed through the second open stub, and combines the in-phase signal,
The detection device according to claim 8, wherein: A first sensor to which a first signal is input,
A second sensor to which a second signal having a phase opposite to the first signal is input,
A combining unit that combines the first signal that has passed through the first sensor and the second signal that has passed through the second sensor to generate an in-phase signal,
A detection unit that detects a voltage of the generated common-mode signal,
A calculating unit that calculates a displacement level or a pressure from the detected voltage,
A detection device comprising: At least one of the first sensor and the second sensor includes a loop coil,
The calculation unit calculates a distance between the loop coil and the measured object as the displacement level,
The detection device according to claim 12, wherein: Each of the first sensor and the second sensor includes a pair of electrode plates spaced apart from each other,
The calculation unit calculates a distance between the pair of electrode plates that changes due to pressure as the pressure,
The detection device according to claim 12, wherein: A movable electrode;
First and second fixed electrodes that are arranged apart from the movable electrode and face each other across the movable electrode,
The first signal that has passed between the movable electrode and the first fixed electrode, and the second signal that has passed between the movable electrode and the second fixed electrode, the voltage of the in-phase signal synthesized A detecting unit for detecting,
A calculating unit for calculating an acceleration from the detected voltage,
A detection device comprising: Two communicators,
The first and second transmission lines having the same line length are arranged between the two communication devices,
A first signal that has passed through the first transmission path, and a second signal that has passed through the second transmission path, and a combiner that generates an in-phase signal by combining them.
A measuring instrument for measuring the generated in-phase signal,
A linear sensor device comprising:

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