JP6456224B2 - Non-contact displacement sensor device - Google Patents

Description

  The present invention relates to a non-contact displacement sensor device, and more particularly to a device that stably detects and measures minute displacement, vibration with a small displacement amount, and the like by a microwave Doppler method.

  Conventionally, there are various methods for measuring displacement and vibration, such as a method using a laser displacement meter, a microphone for detecting vibration of air based on the vibration of an object, and a method of attaching an acceleration sensor to the object. . These methods have merits and demerits depending on their characteristics, and the superiority or inferiority is not clear. For example, in the case of a microphone, sound vibration can be easily extracted using air as a medium. However, since air is used as a medium, attenuation increases when the sensor and the object are shielded by a plate or the like. In the case of an acceleration sensor, the vibration of the object can be directly measured, but it is difficult to measure the vibration of a thin plate because it is necessary to make physical contact.

  In addition, in the cardiopulmonary function monitoring device of Patent Document 1 below, a microwave Doppler sensor is used to detect respiration and heartbeat, and the microwave Doppler sensor is an object whose object reflects radio waves. If it is, there exists an advantage that a displacement, a vibration, etc. can be measured non-contactingly.

JP 2002-65677 A

  By the way, since the above-mentioned microwave Doppler sensor generally obtains a Doppler frequency output proportional to the speed of the moving object, by cutting the direct current and low frequency components of this output by a high pass filter or a band pass filter, Only a moving object can be detected without detecting a stationary object.

  Further, when there is a stationary object in front of the microwave Doppler sensor, the transmission frequency and the reception frequency are the same, and only the phase varies depending on the distance between the sensor (transmission / reception unit) and the object. At this time, the Doppler sensor operates as a phase detector, the output is a DC voltage, and the potential is a value corresponding to the phase difference between the transmission wave and the reception wave.

  However, since the phase difference between the transmitted wave and the received wave in this case depends on the distance from the Doppler sensor to the object, the output voltage varies by 1/2 wavelength of the transmitted wave from the sensor to the object. It will change periodically every time. Therefore, when a microwave Doppler sensor is used as a minute displacement sensor, minute vibration sensor, or the like, there is a problem in that stable detection cannot be performed because the amount of displacement and the amount of change in output voltage differ depending on the distance between the sensor and the object. .

  The present invention has been made in view of the above-described problems, and the object thereof is a non-contact type in which the distance between the sensor and the measurement object can be adjusted to the optimum position, and the detection can be performed with high sensitivity and good linearity. The object is to provide a displacement sensor device.

In order to achieve the above object, a non-contact displacement sensor device according to a first aspect of the present invention includes a transmission / reception unit that transmits and receives microwaves and a 90-degree phase difference as a Doppler frequency signal based on a reception signal from the transmission and reception unit. A quadrature mixer that outputs two I and Q signals, and setting one of the I and Q signals output from the quadrature mixer as the optimum distance between the transceiver and the object The other signal of the I and Q signals is used as a signal for detecting an object.
The invention of claim 2 is provided with a position adjusting mechanism (manually or mechanically automatic) that moves either the transmitter / receiver or the object and adjusts the distance between the transmitter / receiver and the object, The distance between the transmission / reception unit and the object is adjusted by the position adjustment mechanism so that the voltage of the adjustment signal is maximized or minimized.
According to a third aspect of the present invention, a DC cut element for removing a direct current component of the position adjustment signal is provided, and the position adjustment mechanism causes the transmission / reception unit to minimize the amplitude of the position adjustment signal that has passed through the DC cut element. The distance between the object and the object is adjusted, and vibration is detected.

  According to the above configuration, an I signal and a Q signal including Doppler frequency information are output from the orthogonal mixer, and for example, the Q signal is a position adjustment signal and the I signal is a signal for detecting an object. Used. Then, the Q signal that is the position adjustment signal is monitored manually or automatically, and the distance between the transmission / reception unit and the object is moved by moving the transmission / reception unit or the object so that the voltage of the position adjustment signal is maximized or minimized. Is positioned at the optimum distance. As a result, the maximum power is obtained in the I signal that is the object detection signal, and the displacement and vibration of the measurement object are measured with high sensitivity from the I signal.

  The phase difference and output amplitude in the I and Q signals are such that the change in output voltage with respect to the phase change (change in distance) is minimum and the phase difference is 0 when the phase difference between the transmitted wave and the reflected wave is near +90 degrees or −90 degrees. Since the change in the output voltage is the maximum and the linearity is good near the angle of 180 degrees or 180 degrees, the Q signal as the position adjustment signal is the detection signal near +90 degrees or −90 degrees as described above. By setting the relationship where the I signal is in the vicinity of 0 degree or 180 degrees, it is possible to measure in a highly linear state with improved sensitivity.

That is, when the phase difference of the I signal is around 0 degrees, the Q signal voltage is, for example, +1 (the maximum value on the positive side), and when the phase difference of the I signal is around 180 degrees, the Q signal voltage is, for example, − 1 (minimum value on the negative side), so if the distance between the transmitter / receiver and the object is adjusted to the position where the Q signal, which is the position adjustment signal, is maximum or minimum, Detection is possible.
In the case of vibration detection, fine vibrations and the like can be detected well by adjusting the distance between the transmission / reception unit and the object so that the amplitude of the position adjustment signal passing through the DC cut element is minimized. it can.

According to the non-contact displacement sensor device of the present invention, the distance between the sensor and the measurement object can be adjusted to the optimum position, and there is an effect that detection and measurement with high sensitivity and good linearity can be performed.
A microwave Doppler sensor uses a microwave band radio wave as a medium, compares the transmitted wave reflected by the object with the transmitted wave and extracts the difference. If it is a reflecting object, it is possible to measure the vibration and displacement without contact. For example, minute displacements and vibrations of structures, vibrations of musical instruments and aluminum foil films, and the like can be measured from remote positions.
Even if there is a dielectric cover or plate between the sensor and the object to be measured, microwaves pass through with little attenuation, and even when light is blocked by smoke, fog, etc. There is an advantage that measurement below is possible.

It is a figure which shows the structure of the non-contact displacement sensor apparatus of 1st Example which concerns on this invention. It is a figure which shows the structure of the non-contact displacement sensor apparatus of 2nd Example. In the embodiment, the phase relationship when the I signal vector is near the phase difference of 0 degree and the Q signal vector is near the phase difference of 90 degrees (FIG. (A)), the relationship between the phase difference and the output voltage [Figure (B) ] And I and Q signal voltages [FIG. (C)]. In the embodiment, the phase relationship [Fig. (A)] when the I signal vector is near the phase difference of 180 degrees and the Q signal vector is around the phase difference of 270 degrees (or -90 degrees) and the phase difference and the output voltage It is a figure showing a relation [figure (B)].

  FIG. 1 shows the configuration of the non-contact displacement sensor device of the first embodiment, and this first embodiment is mainly used as a minute displacement sensor. As shown in FIG. 1, a transmission antenna 11 and a reception antenna 12 as a transmission / reception unit, a microwave oscillator 14, a distributor 15, and a microwave from the oscillator 14 are input to the sensor unit 10 as local signals. Orthogonal mixers 16a and 16b that output IQ signals having different phases by 90 degrees are provided, and amplification circuits 17a and 17b that amplify the Q signal and the I signal output from the orthogonal mixers 16a and 16b are arranged. Further, the sensor unit 10 is attached to a distance adjustment unit (distance adjustment mechanism: drive mechanism using various actuators) 19 for adjusting the distance between the transmission / reception unit and the measurement object 20. The distance adjustment unit 19 can be connected to a drive circuit 22 that performs drive control for distance adjustment in addition to signal processing using a position adjustment signal, for example.

  When the microwave oscillated from the oscillator 14 is output from the transmission antenna 11, a reflected wave reflected from the measurement object is obtained as a reception signal at the reception antenna 12, and the reception signals are obtained from the orthogonal mixers 16 a and 16 b. , The quadrature mixers 16a and 16b output I and Q signals having a phase difference of 90 degrees.

  In the embodiment, the I signal is used for measuring / detecting the displacement / vibration of the object, the Q signal is used as a position adjustment signal, and the Q signal output from the amplifier circuit 17a is supplied to the drive circuit 22 as a position adjustment signal. Is done. In the drive circuit 22, the distance between the sensor unit 10 and the object 20 is adjusted by adjusting the distance adjustment unit 19 so that the voltage of the Q signal (output) that is the position adjustment signal becomes maximum (or minimum). Positioned at the optimum distance. Then, the displacement and vibration of the object 20 are measured by the subsequent I signal. In the distance adjustment, the drive circuit 22 may automatically set the distance between the transmission / reception unit and the object to the optimum distance using the result of signal processing of the position adjustment signal.

  In the I and Q signals, as shown in FIG. 3, when the phase difference of the I signal (the phase difference between the transmission wave and the reception wave) is around 0 degrees, the phase difference of the Q signal is around +90 degrees, Alternatively, as shown in FIG. 4, when the phase difference of the I signal is around 180 degrees, the phase difference of the Q signal is around 270 degrees (or -90 degrees). That is, the phase difference between the I signal and the Q signal output from the quadrature mixers 16a and 16b is always different by 90 degrees. For example, when the phase difference of the I signal is 0 degrees (voltage 0) as shown in FIG. , The output voltage of the Q signal is maximum (voltage +1), and when the phase difference of the I signal is 180 degrees (voltage 0) as shown in FIG. 4, the output voltage of the Q signal is minimum (voltage −1), and its output The voltage change is linear when the I signal having a phase difference of 0 or 180 degrees is maximum, and the Q signal having a phase difference of 90 degrees or 270 degrees is minimum.

  Therefore, in the embodiment, as shown in FIG. 3C, for example, the drive circuit is configured so that the Q signal near the phase difference of 90 degrees is used as the phase adjustment signal, and the output voltage of the Q signal becomes the maximum (+1). 22 is used to adjust the distance between the sensor unit 10 (transmission / reception antennas 11 and 12) and the object 20, and the I signal (output) near the phase difference of 0 degrees after the distance adjustment is measured and analyzed. Thus, the displacement and vibration of the object are detected. That is, the amount of displacement is measured by amplifying the DC component of the I signal output from the sensor unit 10 by the amplifier circuit 17b.

  Also, as shown in FIG. 4, a Q signal near a phase difference of 270 degrees (−90 degrees) is used as a phase adjustment signal, and the output voltage of the Q signal is minimized (−1) between the transmission / reception unit and the object. The displacement and vibration of the object can also be detected by measuring and analyzing the I signal near 180 degrees after the distance adjustment.

  Further, the voltage increase / decrease direction with respect to the displacement direction is different between the phase relationship of FIG. 3 and the phase relationship of FIG. 4, but the voltage increase / decrease direction is indicated by information on the displacement direction (distant from the reference point). Direction or near direction). That is, as shown in FIG. 3, when the distance between the transmission / reception unit and the object is adjusted so that the voltage of the Q signal (around +90 degrees) as the position adjustment signal is maximized, the phase difference between the transmission wave and the reception wave When the voltage changes in the + direction, that is, when the distance between the transmission / reception unit and the object increases, the voltage of the I signal (near 0 degrees) also increases. On the other hand, as shown in FIG. 4, when the distance between the transmitting / receiving unit and the object is adjusted so that the voltage of the Q signal (around +270 degrees) as the position adjustment signal is minimized, the phase difference between the transmission wave and the reception wave When is changed in the + direction, that is, when the distance between the transmission / reception unit and the object is increased, the voltage of the I signal (around 180 degrees) decreases (the slope of the change is also reversed). Therefore, it is possible to grasp whether the object 20 is displaced in the far direction or the near direction according to the direction of increase / decrease of the voltage, and use it as detection information.

  FIG. 2 shows the configuration of the non-contact displacement sensor device of the second embodiment, and this second embodiment is mainly used as a micro vibration sensor. As shown in FIG. 2, DC cut capacitors 24a and 24b are interposed between the sensor unit 10 and the amplifier circuits 17a and 17b in order to reduce noise, remove DC offset, and the like, and the amplifier circuits 17a and 17b. Then, the signal from which the DC component is removed is amplified with a predetermined amplification factor, and only the change due to vibration is extracted. Further, instead of the DC cut capacitor, a high-pass filter, a band-pass filter, or the like may be used to limit the output frequency band and detect only a vibration component in a desired frequency band with high sensitivity.

  In this case, by adjusting the distance between the sensor unit 10 (transmission / reception antennas 11 and 12) and the object 20 so that the amplitude of the Q signal that is the position adjustment signal is minimized during vibration of the object. The vibration of the object 20 is detected from the I signal after the distance adjustment. As shown in the output waveform of FIG. 2, when the amplitude of the Q signal is minimized, the amplitude of the I signal is maximized.

  In the description of each of the above embodiments, the I signal is used as a signal for detecting an object and the Q signal is used as a position adjustment signal. Conversely, the Q signal is used as a signal for detecting an object and the I signal is used as a position signal. Even in the case of the adjustment signal, similarly, by adjusting the distance between the transmission / reception unit (sensor) and the object to the optimum position, it is possible to realize a displacement sensor and a minute vibration sensor with high detection sensitivity and high linearity. .

  It is possible to measure minute displacements and vibrations of structures, machines, instruments, musical instruments, etc., and can be applied to, for example, measurement of shaking of buildings, shaking of walls and windows due to noise, and the like.

10 ... sensor part,
11: Transmitting antenna,
12 ... receiving antenna,
16a, 16b ... orthogonal mixer,
17a, 17b ... amplifier circuit,
19 ... Distance adjustment part (mechanism),
22 ... Drive circuit,
24a, 24b ... DC cut capacitors.

Claims (3)

A transceiver for transmitting and receiving microwaves;
A quadrature mixer that outputs two I and Q signals that are 90 degrees out of phase as a Doppler frequency signal based on the received signal from the transceiver;
One of the I and Q signals output from the quadrature mixer is used as a position adjustment signal for setting the distance between the transmission / reception unit and the object to be an optimum distance, and the other of the I and Q signals is used. A non-contact displacement sensor device using a signal as a signal for detecting an object. A position adjustment mechanism that moves either the transmission / reception unit or the object and adjusts the distance between the transmission / reception unit and the object is provided,
The non-contact displacement sensor device according to claim 1, wherein the distance between the transmission / reception unit and the object is adjusted by the position adjustment mechanism so that the voltage of the position adjustment signal is maximized or minimized. A DC cut element for removing the DC component of the position adjustment signal is provided,
So that the amplitude of the alignment signal through the DC cut element is minimized by the position adjusting mechanism to adjust the distance between the transceiver and the object, according to claim 2, wherein the detecting vibration Non-contact displacement sensor device.

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