JP2007170990A - Minute movement detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect minute movement of objects with higher accuracy. <P>SOLUTION: A minute movement detector comprises a transmission signal generator for generating a transmission signal having wavelength of a micro wave band; a transmission antenna for irradiating a movement detection object, regarding the transmission signal as a transmission wave; a receiving antenna for outputting reception signal, by capturing reflected waves obtained by reflecting the transmission wave on the movement detection object; a local signal generator for generating local signal of a prescribed frequency; a transmission signal frequency convertor for frequency-converting the transmission signal into a low frequency transmission signal by using the local signal; a reception signal frequency convertor for frequency-converting the reception signal into a low-frequency reception signal by using the local signal; a phase detector for detecting the phase difference between the low-frequency transmission signal and the low-frequency reception signal; and a determination means for determining the moving state of the movement detection object, on the basis of a detection signal of the phase detector. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a minute movement detection device that detects minute movement of an object using a microwave.

  In Patent Document 1 below, the maximum amplitude of a standing wave formed by a microwave having a predetermined wavelength (transmitted wave) and a received wave (reflected wave) obtained by reflecting the transmitted wave on a movement detection object is disclosed. A movement distance detection device that detects a minute movement of a movement detection object by detecting the movement is disclosed.

The amplitude of the standing wave changes sinusoidally according to the position between the reception point and the movement detection object, and the movement detection target is the reception point when the reception point and transmission point of the transmission wave are fixed. When moving in a direction approaching or separating from, the amplitude of the standing wave at the reception point changes in a sine wave shape. In the movement distance detection device, the position where the amplitude of the standing wave that changes in a sine wave is maximized is tracked, and the deviation of the position from the reference position is detected as the movement amount of the movement detection object.
JP 2000-046934 A

  However, in a standing wave that changes in a sine wave shape, the amplitude of the standing wave in the vicinity of the maximum amplitude value is slow, and an error is likely to occur in the detection of the maximum amplitude value of the standing wave. The detection error of the maximum amplitude value becomes the detection error of the minute movement amount as it is. Therefore, the conventional technique has a problem that the detection accuracy of the minute movement amount is lowered due to the detection error of the maximum amplitude value of the standing wave.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to detect a minute movement of an object with higher accuracy.

  In order to achieve the above object, in the present invention, as a first solving means, a transmission signal generator that generates a transmission signal having a wavelength in a microwave band, and the movement detection object is irradiated with the transmission signal as a transmission wave. Using a transmission antenna, a reception antenna that captures a reflected wave obtained by reflecting the transmission wave on an object to be detected and outputs a reception signal, a local signal generator that generates a local signal of a predetermined frequency, and a local signal A transmission signal frequency converter that converts a transmission signal into a low frequency transmission signal, a reception signal frequency converter that converts a reception signal into a low frequency reception signal using a local signal, a low frequency transmission signal, and a low frequency reception A phase detector that detects a phase difference from the signal, and a determination unit that determines a movement state of the movement detection object based on the detection signal of the phase detector. Adopted to.

  As a second solving means, in the first means, the phase switching for switching either the low frequency transmission signal or the low frequency reception signal by a predetermined phase difference based on the first control signal inputted from the determination means. And the determination means controls the first signal delay means by using the first control signal when the detection signal of the phase detector exceeds a predetermined range, thereby controlling the low frequency transmission signal or the low frequency reception. A means is adopted in which either one of the signals is switched by a predetermined phase difference, and the movement state of the movement detection object is determined in consideration of the phase difference.

  As a third solution, in the first or second means, the low frequency reception signal is delayed by a predetermined reference movement amount of the movement detection object based on the second control signal input from the determination means. A signal delay means for non-delaying is further provided, and the determination means controls the signal delay means using the second control signal to obtain a movement amount obtained when the low-frequency received signal is delayed by a predetermined movement amount. And a means for determining an abnormal operation based on whether or not the difference between the movement amount obtained when the delay is not delayed by the predetermined movement amount matches the reference movement amount.

  As a fourth solving means, in any one of the first to third means, a means is adopted in which the transmitting antenna and the receiving antenna are circularly polarized antennas.

  According to the present invention, since the movement state of the movement detection object is determined based on the phase difference between the low-frequency transmission signal and the low-frequency reception signal, the movement of the object is smaller than the conventional technique for detecting the maximum amplitude value. Can be detected with high accuracy.

Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]

  FIG. 1 is a block diagram of a minute movement detection apparatus according to the first embodiment. As shown in FIG. 1, the present minute movement detecting device includes a voltage controlled oscillator 1, a coupler 2, a transmission signal power distributor 3, a PLL (Phase Locked Loop) circuit 4, an attenuator 5, and a transmission signal mixer 6. , Transmitting antenna 7, receiving antenna 8, received signal mixer 9, local signal power distributor 10, local oscillator 11, phase detector 12, and one-chip microcomputer 13.

  The voltage controlled oscillator 1 oscillates a microwave band transmission signal based on the control voltage input from the PLL circuit 4. The frequency of this transmission signal is, for example, 10.525 GHz. The coupler 2 is provided in a signal transmission path between the voltage controlled oscillator 1 and the transmission antenna 7, and outputs a part of the transmission signal output from the voltage controlled oscillator 1 to the transmission signal power distributor 3. The transmission signal power distributor 3 distributes the transmission signal inputted from the coupler 2 to the PLL circuit 4 and the attenuator 5. The PLL circuit 4 generates the control voltage based on the transmission signal input from the transmission signal power distributor 3. The voltage controlled oscillator 1, the coupler 2, the transmission signal power distributor 3, and the PLL circuit 4 form a control loop that controls oscillation of the transmission signal in the voltage controlled oscillator 1. Equivalent to.

  The attenuator 5 is provided in a signal transmission path between the transmission signal power distributor 3 and the transmission signal mixer 6, and attenuates the transmission signal input from the transmission signal power distributor 3 by a predetermined amount. It outputs to the mixer 6 for transmission signals. The transmission signal mixer 6 converts the transmission signal input from the attenuator 5 into a low frequency transmission signal based on the local signal input from the local signal power distributor 10.

  The transmission antenna 7 is a circularly polarized antenna that irradiates the movement detection object (for example, a wall surface of a rock, etc.) with the transmission signal as a transmission wave whose polarization plane turns right. The receiving antenna 8 is a circularly polarized antenna that captures a reflected wave obtained by reflecting the transmitted wave on a movement detection object (not shown) and outputs a received signal. This reflected wave is a microwave in which the transmitted wave is reflected by the movement detection object, and thus the polarization plane is a left-turned wave opposite to the transmitted wave (turned to the right). The transmission antenna 7 and the reception antenna 8 are fixed at positions that are the same distance from the movement detection object.

  The reception signal mixer 9 converts the frequency of the reception signal input from the reception antenna 8 into a low frequency reception signal based on the local signal input from the local signal power distributor 10. The local oscillator 11 oscillates a local signal and outputs it to the local signal power distributor 10. The frequency of this local signal is 9 GHz, for example. The local signal power distributor 10 distributes the local signal input from the local oscillator 11 to the transmission signal mixer 6 and the reception signal mixer 9.

  The phase detector 12 detects the phase difference between the low-frequency transmission signal input from the transmission signal mixer 6 and the low-frequency reception signal input from the reception signal mixer 9 and outputs the detection signal to the one-chip microcomputer 13. . This phase detector 12 has a phase detection characteristic as shown in FIG. 2, that is, a characteristic in which the detection signal increases linearly for a phase difference in the range of 0 to 180 °, and a level in the range of 180 ° to 360 °. The phase difference has a characteristic that the detection signal decreases linearly.

  The one-chip microcomputer 13 corresponds to the determination means in the present embodiment, determines the movement state of the movement detection object based on the detection signal of the phase detector 12, and outputs the determination result to the outside. The one-chip microcomputer 13 includes an A / D converter that quantizes the detection signal (analog signal) described above, a storage unit that stores a predetermined determination processing program, and a detection as a digital signal output from the A / D converter. The CPU includes a central processing unit (CPU) that performs determination processing based on the determination processing program, and an output unit that outputs a determination processing result by the CPU to the outside.

  Next, the operation of the main part of the minute movement detecting apparatus configured as described above will be described in detail with reference to FIG.

  In this minute movement detection device, a transmission wave having a frequency of 10.525 GHz is irradiated from the transmission antenna 7 onto the movement detection object, and this transmission wave is reflected by the movement detection object (similar to the transmission wave). Having a frequency of 10.525 GHz) is received by the receiving antenna 8. The reception timing of the reflected wave based on the transmission timing of the transmission wave is obtained by adding the time for the reflected wave to propagate from the movement detection object to the reception antenna 8 to the time for the transmission wave to propagate from the transmission antenna 7 to the movement detection object. Will be.

  That is, the phase difference between the transmission wave and the reception wave changes according to the distance between the transmission antenna 7 (reception antenna 8) and the moving detection object of the microwave (transmission wave and reception wave) having a frequency of 10.525 GHz. Will be. As shown in FIG. 3, the reflected wave 1 when the rock wall surface (movement detection object) is at position A and the reflected wave 2 when the rock wall surface is at position B have different phase differences with respect to the transmitted wave. Yes.

  Such a phase difference between the transmission wave and the reception wave is a value corresponding to the distance between the minute movement detection device and the movement detection target, and is synonymous with a phase difference between the transmission signal and the reception signal. Therefore, when the present minute movement detection device is fixedly installed so as not to change its position, it is possible to determine the movement state of the movement detection object by detecting the phase difference between the transmission signal and the reception signal.

  In the present minute movement detection device, a transmission signal having extremely high frequency stability is generated by the above-described control loop, and based on such a transmission signal, a transmission wave is irradiated from the transmission antenna 7 to the movement detection object, and a reflected wave is generated. Captured by the receiving antenna 8. The transmission signal is frequency-converted to a low-frequency transmission signal by the transmission signal mixer 6, while the reception signal is frequency-converted to a low-frequency reception signal by the reception signal mixer 9, and the low-frequency transmission signal, the low-frequency reception signal, Is detected by the phase detector 12. The low-frequency transmission signal and the low-frequency reception signal are frequency-converted by the same local signal, and therefore the phase difference is the same as the phase difference between the transmission signal and the reception signal before frequency conversion.

  In the determination processing program incorporated in the one-chip microcomputer 13, frequency information of the transmission wave (reception wave), that is, “10.525 GHz” is captured as data, and the one-chip microcomputer 13 performs phase detection based on the determination processing program. Based on the detection signal input from the detector 12, that is, the phase difference between the low frequency transmission signal and the low frequency reception signal and the frequency door of the transmission wave (reception wave), the movement distance of the movement detection object is calculated. When the result exceeds a predetermined threshold value, an alarm signal is output to the outside.

According to this embodiment, since the movement state of the movement detection object is determined based on the phase difference between the low-frequency transmission signal and the low-frequency reception signal, the movement is performed more than the conventional technique for detecting the maximum amplitude value. The minute movement of the detection target can be detected with high accuracy.
In addition, since the transmission signal with extremely high frequency stability is generated by the control loop described above, and the low frequency transmission signal and the low frequency reception signal are generated by the same local signal, this also improves the detection accuracy of minute movement. Can be improved.
Further, by using circularly polarized antennas as the transmitting antenna 7 and the receiving antenna 8, it is possible to eliminate the influence of disturbance radio waves other than circularly polarized waves, and this can also improve the detection accuracy of minute movement.

[Second Embodiment]
FIG. 4 is a block diagram of the minute movement detection device according to the second embodiment. As can be easily understood from FIG. 4, the present minute movement detection device is different from the minute movement detection device according to the first embodiment in that the phase switch 14 controlled by the one-chip microcomputer 13 </ b> A is combined with the reception signal mixer 9. This is added between the phase detector 12. The phase switch 14 switches the phase of the low-frequency reception signal by 90 ° by a control signal input from the one-chip microcomputer 13A.

  With reference to FIG. 2, the operation of the minute movement detection device configured as described above will be described. Initially, the position of the minute movement detection device with respect to the movement detection object has a phase difference of 0 to 180 ° (increase in a straight line). It is set to be an intermediate position of the region), that is, 90 °. In this state, when the movement detection object moves minutely in a direction toward or away from the minute movement detection device, the phase difference increases or decreases from 90 °, and the value of the detection signal is linear along the phase detection characteristics. Will increase or decrease.

  For example, when the phase difference increases due to a slight movement in the direction in which the movement detection target approaches, the one-chip microcomputer 13A outputs a control signal to the phase switch 14 to reduce the phase difference. The phase of the frequency reception signal is switched by 90 °. As a result, since the phase of the low-frequency transmission signal is not switched, the phase difference between the low-frequency transmission signal and the low-frequency reception signal changes from 135 ° to 45 °. When the phase switching of the low frequency reception signal by the phase switch 14 is performed, the 45 ° phase difference in the phase switch 14 is shifted from 135 ° by the phase switching of the low frequency reception signal. The microcomputer 13A recognizes the 45 ° phase difference in the phase switch 14 as 135 ° (= actual phase difference).

  Such phase switching of the low-frequency received signal is repeated even when the phase difference reaches 135 ° again after further switching in the direction in which the object to be moved approaches after the switching, and in this case, one chip Since the microcomputer 13A is the second phase switching, the phase difference after the switching is recognized as 135 ° + 90 ° = 225 °. That is, the one-chip microcomputer 13A recognizes a phase difference obtained by adding a phase difference obtained by multiplying the phase difference indicated by the detection signal of the phase switch 14 by 90 ° to the number of times of phase switching as an actual phase difference. The same applies to the case where the phase difference is reduced by a slight movement of the movement detection object in the direction of moving away.

  As shown in FIG. 2, the phase difference characteristic of the phase detector 12 is formed from a linear increase range (0 ° to 180 °) and a linear decrease range (180 ° to 360 °). A phase difference that is symmetrical about the center. For example, at 90 ° and 250 °, the value of the detection signal is the same, and thus both phase differences cannot be identified from the value of the detection signal. Therefore, the phase difference cannot be detected across the linear increase range and the linear decrease range, and only the linear increase range or the linear decrease range must be used. That is, the phase difference detection range is 0 to 0. It is limited to 180 ° or 180 ° to 360 °.

  However, according to the second embodiment, as described above, the phase switch 14 performs phase switching of the low-frequency received signal and the one-chip microcomputer 13A recognizes the actual phase difference according to the phase switching. The detection range can be unlimited in principle.

  In the above description, the case of using the range of 45 ° to 135 ° among the phase difference characteristics of the phase detector 12 has been described. However, it may be in the range of 0 ° to 180 ° or 180 ° to 360 °. Any range is acceptable. In the second embodiment, the phase difference characteristic of the phase detector 12 is actually poor in linearity in the vicinity of 0 °, 180 °, and 360 ° as compared with the linearity of 90 ° and 270 °. Then, in order to set the range with better linearity as the phase difference detection range, the phase of the low frequency received signal is switched with the phase difference of 45 ° and 135 °.

  In the second embodiment, the phase of the low-frequency transmission signal is switched by the phase detector 12, but the phase of the low-frequency transmission signal may be switched by the phase detector 12. .

[Third Embodiment]
FIG. 5 is a block diagram of the minute movement detection device according to the third embodiment. As can be easily understood from FIG. 5, the present minute movement detection device is different from the minute movement detection device according to the first embodiment in that a reference delay switch 15 controlled by the one-chip microcomputer 13B is replaced with a reception signal mixer 9. And the phase detector 12 are added. The reference delay switch 15 performs switching to delay the delay amount of the low-frequency received signal by the reference movement amount by the control signal input from the one-chip microcomputer 13B.

  That is, as shown in FIG. 6, the reference delay switch 15 sets the delay amount of the first transmission line L1 (microstrip line) that hardly gives a delay to the low-frequency reception signal and the delay amount of the first transmission line L1. A second transmission path L2 (microstrip line) that gives a delay of a delay amount obtained by adding a delay amount corresponding to the reference movement amount to the low-frequency received signal, and the first and second transmission paths L1 and L2 are Switching is performed based on a control signal input from the one-chip microcomputer 13B. Such a reference delay switch 15 is provided to detect an operation abnormality of the minute movement detection device as described below.

  The one-chip microcomputer 13B outputs a control signal to the reference delay switch 15 at a predetermined time interval in order to detect an abnormal operation of the minute movement detecting device, and outputs the first transmission line L1 and the second transmission line L2. Switch. If the difference in the minute movement amount before and after the switching matches the reference movement amount, it is determined that the present minute movement detection device is operating normally, and if it does not match, it is determined that there is an abnormality. . Then, this determination result is output to the outside.

  As described above, the first transmission line L1 and the second transmission line L2 in the reference delay switch 15 are physically formed as microstrip lines, and the reference movement is performed according to the length of the microstrip line. The delay amount corresponding to the amount is formed. Therefore, the reference movement amount as a characteristic of the reference delay switch 15 can be considered to be almost unchanged.

  Therefore, when the minute movement amount obtained when switching between the first transmission line L1 and the second transmission line L2 having such properties does not match the reference movement amount unique to the reference delay switch 15, It can be considered that there is some abnormality in this minute movement detection device. The one-chip microcomputer 13B internally stores the minute movement amount obtained when the first transmission path L1 and the second transmission path L2 are switched during the initial setting of the present minute movement detection apparatus as a reference movement amount. Thereafter, it is determined whether or not the minute movement amount obtained when the first transmission line L1 and the second transmission line L2 are switched at a predetermined time interval matches the reference movement amount stored therein. Thus, the occurrence of an abnormality in the minute movement detection device is periodically monitored.

  According to the present embodiment, since the occurrence of abnormality is regularly monitored by the one-chip microcomputer 13B, it is possible to prevent the detection of uncertain minute movement due to the occurrence of the abnormality, and thus the minute of the movement detection target object. The movement can be detected with high accuracy.

It is a block diagram which shows the function structure of the micro movement detection apparatus which concerns on 1st Embodiment of this invention. It is a special drawing which shows the phase detection characteristic of the phase detector 12 in the micro movement detection apparatus concerning 1st Embodiment of this invention. It is a schematic diagram which shows the principle of operation of the micro movement detection apparatus which concerns on 1st Embodiment of this invention. It is a block diagram which shows the function structure of the micro movement detection apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the function structure of the micro movement detection apparatus which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the reference | standard delay switch 15 in the micro movement detection apparatus which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Voltage controlled oscillator, 2 ... Coupler, 3 ... Transmission signal power divider, 4 ... PLL circuit, 5 ... Attenuator, 6 ... Transmission signal mixer, 7 ... Transmission antenna, 8 ... Reception antenna, 9 ... Reception signal mixer DESCRIPTION OF SYMBOLS 10 ... Local signal power distributor, 11 ... Local oscillator, 12 ... Phase detector, 13 ... One-chip microcomputer

Claims (4)

A transmission signal generator for generating a transmission signal having a wavelength in the microwave band;
A transmission antenna that irradiates the movement detection object as a transmission wave with the transmission signal;
A receiving antenna that captures a reflected wave obtained by reflecting the transmission wave on a moving detection object and outputs a reception signal;
A local signal generator for generating a local signal of a predetermined frequency;
A transmission signal frequency converter that converts a transmission signal into a low-frequency transmission signal using a local signal;
A received signal frequency converter that converts a received signal into a low frequency received signal using a local signal; and
A phase detector for detecting a phase difference between the low frequency transmission signal and the low frequency reception signal;
And a determination means for determining a movement state of the movement detection object based on a detection signal of the phase detector. Further comprising a phase switch that switches either the low-frequency transmission signal or the low-frequency reception signal by a predetermined phase difference based on the first control signal input from the determination means;
When the detection signal of the phase detector exceeds a predetermined range, the determination means controls either the low frequency transmission signal or the low frequency reception signal by controlling the phase switch using the first control signal. The minute movement detection device according to claim 1, wherein only the phase difference is switched, and the movement state of the movement detection object is determined in consideration of the phase difference. Signal delay means for delaying / non-delaying the low-frequency received signal by a predetermined reference movement amount of the movement detection object based on the second control signal input from the determination means;
The determination means controls the signal delay means by using the second control signal to move the low-frequency reception signal when the low-frequency received signal is delayed by a predetermined movement amount and when the delay is not delayed by the predetermined movement amount. The minute movement detection device according to claim 1 or 2, wherein an operation abnormality is determined based on whether or not a difference from the obtained movement amount matches a reference movement amount. 4. The minute movement detection device according to claim 1, wherein the transmitting antenna and the receiving antenna are circularly polarized antennas.

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