JP6003432B2 - Moving object detection sensor - Google Patents

Description

The technology disclosed in this specification relates to a moving object detection sensor .

  Patent Document 1 discloses a distance measuring device that measures a distance to an object by transmitting a radio signal from a transmission antenna and receiving a radio signal reflected by the object with a reception antenna.

JP 2007-86015 A

In the distance measuring apparatus of Patent Document 1, a signal received by a receiving antenna is amplified by an amplifier circuit. There is an active element such as an amplifier in the amplifier circuit, and there is a problem that noise is superimposed on the signal due to the operation of these active elements and detection accuracy is lowered. Therefore, the present specification provides a moving object detection sensor that is less susceptible to noise.

The moving object detection sensor disclosed in this specification includes a transmission line, an oscillator connected to the transmission line, a variable load connected to the transmission line and capable of changing its own impedance, and connected to the transmission line. A signal detector connected to the transmission line, and an amplitude change detector . The high frequency signal input to the transmission line by the oscillator is transmitted to the variable load and the antenna. The variable load reflects high frequency signals. The antenna transmits a high frequency signal input from the transmission path to the antenna as a radio signal, and inputs a radio signal received by the antenna as a high frequency signal to the transmission path. The high-frequency signal reflected by the variable load and the high-frequency signal input to the transmission path by the antenna are transmitted to the signal detector via the transmission path. An amplitude change detector detects a change over time in the amplitude of the high-frequency signal detected by the signal detector.

In this moving object detection sensor , a high frequency signal is transmitted from an oscillator to a variable load and an antenna through a transmission path. The variable load reflects high frequency signals. The antenna transmits a high frequency signal as a radio signal. When the transmitted radio signal hits an object, the radio signal is reflected by the object. The reflected radio signal is received by the antenna and input to the transmission path as a high frequency signal. As a result, the signal detector combines a high-frequency signal reflected from a variable load (hereinafter referred to as a reflected signal) and a high-frequency signal input from an antenna (hereinafter referred to as a received signal) (hereinafter referred to as a combined signal). Signal). When the reflected signal and the received signal are in a mutually reinforcing relationship (when the phase difference between these signals is zero), the amplitude of the combined signal is increased. When the reflected signal and the received signal cancel each other (when the phase difference between these signals is 180 °), the amplitude of the combined signal becomes small. Therefore, if the object reflecting the radio signal moves relative to the moving object detection sensor , the amplitude of the combined signal detected by the signal detector changes with time. Therefore, the presence or absence of a moving object can be detected by detecting this change in amplitude. Note that the detection sensitivity of the moving object detection sensor is the maximum value of the amplitude of the combined signal (the amplitude in the case of the reinforcing relationship) and the minimum value of the amplitude of the combined signal (the amplitude in the case of the canceling relationship). The higher the ratio (hereinafter referred to as the amplitude ratio), the higher the ratio. The amplitude ratio increases as the difference between the amplitude of the received signal and the amplitude of the reflected signal decreases. The amplitude of the received signal varies depending on the position, size, material, and the like of the object that reflects the radio signal (that is, the detection target object). Thus, the amplitude ratio can be improved if the amplitude of the reflected signal can be matched to the received signal whose amplitude varies depending on the situation. In this moving object detection sensor , the impedance of the variable load can be changed. The reflectivity when the variable load reflects a high-frequency signal varies depending on the ratio between the impedance of the variable load and the impedance of the transmission path. Therefore, when the impedance of the variable load is changed, the reflectance of the high frequency signal at the variable load changes, and the amplitude of the reflected signal changes. Thereby, the amplitude of the reflected signal can be matched with the amplitude of the received signal. That is, the amplitude ratio can be improved. Thus, this moving object detection sensor can improve the amplitude ratio without performing signal amplification. Therefore, the synthesized signal can be optimized without being affected by the noise of the amplifier. Note that the present technology does not completely deny the use of amplifiers. For example, the combined signal optimized by the present technology may then be amplified by an amplifier. Even in such a case, the detection sensitivity can be improved by optimizing the composite signal before amplification.

1 is a schematic configuration diagram of an object detection device 10. FIG. 1 is a schematic configuration diagram of an object detection device 10. FIG. The graph which shows an example of the signal input into a signal detector. The graph which shows an example of the signal input into a signal detector. The graph which shows an example of the signal input into a signal detector. The graph which shows an example of the signal input into a signal detector. The flowchart which shows the process which the control apparatus 64 performs. FIG. 5 is a schematic configuration diagram of an object detection apparatus 100 according to a second embodiment. 9 is a flowchart illustrating processing executed by the control device 64 according to the second embodiment. 6 is a graph showing a change in impedance of a variable load 40 in Example 2.

  First, the features of the embodiments described below are listed. Note that the features listed here are all independently effective.

  (Characteristic 1) The transmission path is configured by a 3 dB hybrid coupler.

According to the feature 1, the transmission path of the high frequency signal can be extremely shortened. Therefore, thermal noise generated in the transmission line can be minimized. Therefore, the sensitivity of the moving object detection sensor can be further improved.

(Feature 2) The moving object detection sensor repeatedly executes the first step and the second step. In the first step, the impedance of the variable load is set to a predetermined value (for example, substantially the same impedance as that of the transmission line), a high frequency signal is input from the oscillator to the transmission line, and detection is performed by the signal detector. In the second step, a high frequency signal is input from the oscillator to the transmission line, and detection is performed by a signal detector. In the second step, the impedance of the variable load is changed so that the reflectivity of the high frequency signal at the variable load increases as the amplitude of the high frequency signal detected by the signal detector in the immediately preceding first step increases. In one embodiment, the impedance of the variable load in the second step is larger than the impedance of the transmission line. In this embodiment, the impedance of the variable load is changed so that the impedance of the variable load increases as the amplitude of the high-frequency signal detected by the signal detector in the first step immediately before increases.

A moving object detection sensor 10 shown in FIG. 1 includes a transmission line 20, an oscillator 30, a variable load 40, an antenna 50, a signal detector 60, and a control device 64. The transmission line 20 is formed on a substrate (not shown) and is made of a conductor. The oscillator 30, the variable load 40, the antenna 50, and the signal detector 60 are connected to the transmission line 20. The transmission line 20 connects a portion 20a extending linearly from the oscillator 30 toward the variable load 40, a portion 20b extending linearly from the antenna 50 toward the signal detector 60, and a portion 20a and a portion 20b. It has two linear portions 20c and 20d. The transmission line 20 has an impedance of about 50Ω with respect to the high frequency signal oscillated by the oscillator 30.

The control device 64 controls each part of the moving object detection sensor 10.

  The oscillator 30 inputs a high frequency signal to the transmission line 20. Part of the high-frequency signal (about 50% of the input power) input from the oscillator 30 to the transmission path 20 is transmitted to the variable load 40 through the path indicated by the arrow 70a. Part of the high-frequency signal (about 50% of the remaining input power) input from the oscillator 30 to the transmission line 20 is input to the antenna 50 through paths indicated by arrows 70b and 70c. The shape of the transmission line 20 is such that a high-frequency signal input from the oscillator 30 to the transmission line 20 is hardly input to the signal detector 60.

  The variable load 40 has a higher impedance than the transmission line 20. For this reason, the variable load 40 reflects the signal input from the transmission line 20 to the transmission line 20. The structure of the variable load 40 will be described in more detail. The variable load 40 includes a DC power source 42, an inductor 44, a capacitor 46, and a diode 48. The current supplied by the DC power source 42 is variable. Since the capacitor 46 cuts off the direct current and the inductor 44 does not become a load with respect to the direct current, the current from the direct current power source 42 flows to the diode 48 as shown by an arrow 80 in FIG. On the other hand, the capacitor 46 passes a high-frequency signal and the inductor 44 blocks the high-frequency signal, so that the high-frequency signal from the transmission line 20 is input to the diode 48. That is, the impedance of the variable load 40 with respect to the high frequency signal is determined by the impedance of the diode 48. The impedance of the diode 48 varies depending on the magnitude of the direct current 80 flowing through the diode 48. That is, the larger the DC current 80, the smaller the impedance of the diode 48. That is, the impedance of the diode 48 with respect to the high frequency signal (that is, the impedance of the variable load 40 with respect to the high frequency signal) can be changed by the energization current from the DC power source 42. When the impedance of the variable load 40 with respect to the high frequency signal changes, the reflectance of the high frequency signal at the variable load 40 changes.

  The antenna 50 transmits a high-frequency signal input from the transmission path 20 to the antenna 50 as a radio signal to the surrounding space. When an object (for example, the object 90 in FIG. 1) exists in the surrounding space, the radio signal transmitted by the antenna 50 is reflected by the object. The radio signal reflected by the object is received by the antenna 50 as shown in FIG. 2 and input to the transmission line 20 as a high frequency signal. Note that the amplitude of the radio signal received by the antenna 50 varies depending on the position and size of the object. If an object is present at a position close to the antenna 50, a high-amplitude radio signal is received by the antenna 50. If an object exists at a position far from the antenna 50, a low-amplitude radio signal is received by the antenna 50. Therefore, the amplitude of the high-frequency signal input from the antenna 50 to the transmission path 20 changes according to the surrounding environment. Further, when there is no object in the surrounding space, the antenna 50 hardly receives a radio signal.

As shown in FIG. 2, the high-frequency signal reflected by the variable load 40 is transmitted to the signal detector 60 through paths indicated by arrows 70d and 70e. A high-frequency signal input from the antenna 50 to the transmission path 20 is transmitted to the signal detector 60 through a path indicated by an arrow 70f. Thus, both the high frequency signal from the variable load 40 and the high frequency signal from the antenna 50 are input to the signal detector 60. Note that signals from the variable load 40 and the antenna 50 are transmitted to the oscillator 30 and the like through a path (not shown), but the high-frequency signal transmitted through such a path hardly affects the operation of the moving object detection sensor 10.

  3 and 4 show the high-frequency signals (that is, the high-frequency signal A from the antenna 50 and the high-frequency signal B from the variable load 40) that are input to the signal detector 60 when the radio signal is reflected by the object 90 in FIG. And a synthesized wave C) of the high frequency signal A and the high frequency signal B. The phase of the high-frequency signal A input from the antenna 50 to the transmission path 20 varies depending on the position of the object 90 (that is, the position where the object 90 reflects the radio signal). As shown in FIG. 3, when the high-frequency signal A from the antenna 50 matches the phase of the high-frequency signal B from the variable load 40, the signal detector 60 detects the high-frequency signal C having a high amplitude D1. When the position of the object 90 changes and the high frequency signal A from the antenna 50 is shifted by 180 ° from the phase of the high frequency signal B from the variable load 40 as shown in FIG. 4, the signal detector 60 has a low amplitude D2. A high-frequency signal C is detected. That is, according to the position of the object 90, the amplitude of the high frequency signal C detected by the signal detector 60 changes. Therefore, the presence or absence of a moving object can be detected based on whether or not the amplitude of the high-frequency signal C changes.

Here, as the ratio D1 / D2 between the maximum value D1 and the minimum value D2 of the amplitude of the high-frequency signal C detected by the signal detector 60 is larger, the sensitivity of the moving object detection sensor 10 is improved. For example, as shown in FIGS. 5 and 6, if the amplitude of the high frequency signal B from the variable load 40 matches the amplitude of the high frequency signal A from the antenna 50, the maximum value D1 of the amplitude of the high frequency signal C is The minimum value D2 of the amplitude of the high frequency signal C becomes substantially zero, and the amplitude ratio D1 / D2 becomes substantially infinite. In this case, the sensitivity of the moving object detection sensor 10 is extremely high. The moving object detection sensor 10 improves its detection sensitivity by changing the impedance of the variable load 40 so that the amplitude ratio D1 / D2 of the high-frequency signal C is increased.

Next, a process for adjusting the impedance of the variable load 40 will be described. When the moving object detection sensor 10 is operated, the control device 64 executes the flowchart shown in FIG. In step S2, the control device 64 sets the impedance of the variable load 40 with respect to the high-frequency signal to 50Ω (that is, controls the current value of the DC power supply 42 so that the impedance becomes 50Ω). As described above, the impedance of the transmission line 20 is about 50Ω. Therefore, in this case, since the impedance of the variable load 40 and the impedance of the transmission line 20 are substantially the same, the reflectance of the high frequency signal at the variable load 40 is approximately 0%. Next, the control device 64 operates the oscillator 30. As a result, a high frequency signal is input from the oscillator 30 to the transmission line 20. As described above, since the reflectivity of the high frequency signal at the variable load 40 is approximately 0%, the reflection by the variable load 40 hardly occurs (that is, the above-described high frequency signal B hardly occurs). The high frequency signal from the oscillator 30 is input to the antenna 50, and a radio signal is transmitted from the antenna 50. The transmitted radio signal is reflected by the object, and the reflected radio signal is received by the antenna 50. For this reason, the high frequency signal A is input from the antenna 50 to the transmission path 20. The high frequency signal A input from the antenna 50 to the transmission path 20 is input to the signal detector 60. Therefore, the signal detector 60 detects only the high frequency signal A from the antenna 50. As described above, if an object is present near the moving object detection sensor 10, the amplitude of the high-frequency signal A is increased. In step S2, the control device 64 specifies the amplitude of the high-frequency signal A.

In step S4, the control device 64 increases the impedance of the variable load 40 to a value higher than the impedance of the transmission line 20 (that is, 50Ω). As a result, the high frequency signal is reflected by the variable load 40, and the reflected high frequency signal B is input to the signal detector 60. That is, the signal detector 60 detects the high frequency signal C obtained by synthesizing the high frequency signal A and the high frequency signal B. If there is a change in the amplitude of the high-frequency signal C detected by the signal detector 60 in step S4, the control device 64 outputs a signal to that effect. Thus, it is detected whether or not there is a moving object within the measurement range of the moving object detection sensor 10.

  In step S4, the impedance of the variable load 40 is changed to a value corresponding to the amplitude of the high-frequency signal A specified in step S2. More specifically, in step S4, the impedance of the variable load 40 is set to a larger value as the amplitude of the high-frequency signal A specified in step S2 is larger. As the impedance of the variable load 40 is increased, the difference between the impedance of the variable load 40 and the impedance of the transmission line 20 is increased, so that the reflectivity of the high frequency signal at the variable load 40 is increased. Therefore, if the impedance of the variable load 40 is controlled in this way, the amplitude of the high frequency signal B reflected by the variable load 40 increases as the amplitude of the high frequency signal A increases. As a result, it is possible to suppress a large difference between the amplitudes of the high-frequency signal A and the high-frequency signal B. In step S4, the impedance of the variable load 40 is set so that the amplitude of the high-frequency signal B substantially matches the amplitude of the high-frequency signal A. For this reason, the amplitude ratio D1 / D2 of the high frequency signal C detected by the signal detector 60 is maintained at a high value.

The control device 64 repeats step S2 and step S4 at a constant cycle. Therefore, even if the amplitude of the high-frequency signal A changes with time due to changes in the surrounding environment, the amplitude of the high-frequency signal B changes so as to follow it. Therefore, the moving object detection sensor 10 can always detect a moving object with high sensitivity.

Thus, according to the technique of the first embodiment, a moving object can be detected with high sensitivity without using an amplifier such as an amplifier. Since an amplifier is not used, noise due to the amplifier does not occur in the high-frequency signal, and the noise in the high-frequency signal is only thermal noise. Therefore, according to this technique, it is possible to realize a highly sensitive moving object detection sensor that is hardly affected by noise.

In the above-described embodiment, the transmission line 20 is configured by a 3 dB hybrid coupler. That is, the oscillator 30 is connected to one end of the linear portion 20a of the 3 dB hybrid coupler, the variable load 40 is connected to the other end of the linear portion 20a, and one end of the linear portion 20b. The antenna 50 is connected diagonally to the oscillator 30, and the signal detector 60 is connected to the other end of the linear portion 20b. According to such a configuration, the transmission path of the high frequency signal can be extremely shortened. Therefore, thermal noise generated in the transmission line 20 can be minimized. For this reason, the sensitivity of the moving object detection sensor 10 is further improved.

Further, in the first embodiment, when the control device 64 repeats the processing of FIG. 7, the control unit 64 changes the impedance of the variable load 40 (or the change of the impedance of the variable load 40 such as the current value of the DC power supply 42). May be output. In the first embodiment, the amplitude of the high frequency signal A and the impedance of the variable load 40 are accurately correlated. When the object to be detected is approaching the moving object detection sensor 10, since the amplitude of the high-frequency signal A gradually increases, the impedance of the variable load 40 also gradually increases. When the object to be detected is moving away from the moving object detection sensor 10, the amplitude of the high-frequency signal A is gradually reduced, so that the impedance of the variable load 40 is also gradually reduced. Therefore, by outputting the transition of the impedance of the variable load 40, it is possible to determine whether the object is approaching or moving away from the moving object detection sensor 10.

  In Example 1, in step S4, the impedance of the variable load 40 is set to a value higher than the impedance of the transmission line 20, and the higher the amplitude of the high-frequency signal A specified in step S2, the more variable in step S4. The impedance of the load 40 is increased. However, in another embodiment, the impedance of the variable load 40 is set to a value lower than the impedance of the transmission line 20 in step S4, and the higher the amplitude of the high-frequency signal A specified in step S2, the larger in step S4. The impedance of the variable load 40 may be reduced. Even in such a configuration, the larger the amplitude of the high-frequency signal A, the larger the impedance difference between the transmission line 20 and the variable load 40 (that is, the amplitude of the high-frequency signal B reflected by the variable load 40). it can.

The moving object detection sensor 100 according to the second embodiment detects the presence of a plurality of objects 90 and 92 as shown in FIG. The moving object detection sensor 100 of the second embodiment is different from the moving object detection sensor 10 of the first embodiment only in the control method. The control device 64 of the moving object detection sensor 100 according to the second embodiment executes the process shown in the flowchart of FIG. In the flowchart of FIG. 9, step S1 is added to the flowchart of FIG. Moreover, the graph D of FIG. 10 has shown transition of the impedance of the variable load 40 when the process of FIG. 9 is performed. In step S1, the control device 64 sets the output intensity of the oscillator 30. In the first step S1, the output intensity is set to a very low value. Steps S2 and S4 are performed in the same manner as in FIG. However, in steps S <b> 2 and 4, the high-frequency signal having the output intensity set in step S <b> 1 is output from the oscillator 30. Since the output intensity is set to be extremely low in the first step S1, a high frequency signal having a very small amplitude is output from the oscillator 30 in the first step S2. For this reason, in the first step S <b> 2, the propagation distance of the radio signal transmitted from the antenna 50 is extremely short, and the radio signal does not reach the object 90. Therefore, in the first step S2, the amplitude of the high frequency signal A detected by the signal detector 60 is substantially zero. Therefore, in the subsequent step S4, the impedance of the variable load 40 is set to approximately 50Ω (that is, the reflectance is approximately zero). In step S1 after the second time, the output intensity of the oscillator 30 is increased by a predetermined value. Then, the subsequent steps S2 and S4 are performed according to the output intensity set in step S1. The control device 64 repeats a loop composed of steps S1, S2, and S4. By repeating this loop, the output intensity of the oscillator 30 gradually increases. The radio signal transmitted from the antenna 50 does not reach the object 90 while the output intensity of the oscillator 30 is low. Therefore, during this period, as shown in the period T1 in FIG. 10, the impedance of the variable load 40 is maintained at about 50Ω. When the output intensity of the oscillator 30 increases (that is, the propagation distance of the radio signal increases), when the radio signal reaches the object 90, the radio signal is reflected by the object 90. Then, the high frequency signal A is detected by the signal detector 60 in step S2. Therefore, in step S4 immediately after that, the impedance of the variable load 40 is increased. Thereafter, as the output intensity of the oscillator 30 increases, the intensity of the radio signal reflected by the object 90 also increases, so that the amplitude of the high-frequency signal A detected by the signal detector 60 also gradually increases. Therefore, as shown in the period T <b> 2 in FIG. 10, the impedance of the variable load 40 gradually increases in accordance with the amplitude of the high-frequency signal A. Thereafter, when the radio signal is reflected by the two objects 90 and 92, the signal detector 60 detects the high-frequency signal A having a larger amplitude. For this reason, as shown in the period T3 in FIG. 10, the rate of increase in the impedance of the variable load 40 becomes larger. When the output intensity of the oscillator 30 reaches a predetermined maximum value, the control device 64 sets the output intensity to the initial value again and repeats the loop composed of steps S1, S2, and S4 again.

  As described above, when the impedance of the variable load 40 is adjusted while gradually increasing the output intensity of the oscillator 30, when the radio signal reaches the objects 90 and 92, the rate of increase in impedance as shown in FIG. Changes. Therefore, the position of the object can be detected by specifying the change point of the rate of increase in impedance (change points 110 and 112 in FIG. 10). According to this method, it is possible to detect the positions of a plurality of objects.

A graph E in FIG. 10 shows the transition of the impedance of the variable load 40 obtained when the processing in FIG. 9 is performed again after the processing when the graph D is obtained. As illustrated, in graph E, the change point 110 has moved to the change point 120 and the change point 112 has moved to the change point 122. Thereby, the amount of movement of the objects 90 and 92 can be detected. Further, the rate of increase in impedance (that is, the slopes of the graphs D and E) in FIG. 10 correlates with the range of the radio signal received by the objects 90 and 92 (solid angle θ in FIG. 8). The larger the solid angle θ in the range in which the wireless signal is received, the higher the rate of increase in impedance. Therefore, the solid angle θ of each of the objects 90 and 92 can be specified from the slope of the impedance graph. When the solid angle θ and the positions of the objects 90 and 92 (that is, the distances L90 and L92 from the antenna 50 to the objects 90 and 92 shown in FIG. 8) are known, the projected areas of the objects 90 and 92 in the radio signal irradiation direction (see FIG. 8 area S90, S92). As described above, according to the moving object detection sensor 100 of the second embodiment, the movement amounts of the objects 90 and 92 and the projection areas of the objects 90 and 92 in the wireless signal irradiation direction can be specified.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10: Moving object detection sensor 20: Transmission path 30: Oscillator 40: Variable load 42: DC power supply 44: Inductor 46: Capacitor 48: Diode 50: Antenna 60: Signal detector 64: Controller 80: DC current

Claims (6)

A moving object detection sensor for detecting the presence of a moving object,
A transmission line;
An oscillator connected to the transmission line;
A variable load connected to the transmission line and capable of changing its own impedance;
An antenna connected to the transmission line;
A signal detector connected to the transmission line,
Amplitude change detector,
Have
The high-frequency signal input to the transmission line by the oscillator is transmitted to the variable load and the antenna,
Variable load reflects high frequency signals,
The antenna transmits a high-frequency signal input from the transmission path to the antenna as a radio signal, and inputs a radio signal received by the antenna to the transmission path as a high-frequency signal.
The high frequency signal reflected by the variable load and the high frequency signal input to the transmission line by the antenna are transmitted to the signal detector by the transmission line ,
An amplitude change detector detects a change in amplitude of the high frequency signal detected by the signal detector over time;
A moving object detection sensor . The moving object detection sensor according to claim 1, wherein the transmission path is configured by a 3 dB hybrid coupler. The transmission line has a linear first part, a linear second part extending along the first part, and a plurality of linear parts connecting the first part and the second part. And
An oscillator is connected to one end of the first part;
A variable load is connected to the other end of the first portion;
An antenna is connected to one end of the second part located diagonally to the oscillator;
A signal detector is connected to the other end of the second part;
The moving object detection sensor according to claim 2. It is configured to repeatedly execute the first step and the second step,
In the first step, with the variable load impedance set so that the reflectivity of the high frequency signal at the variable load becomes the first value, the high frequency signal is input from the oscillator to the transmission line and detected by the signal detector. ,
In the second step, the signal detector is configured by inputting the high frequency signal from the oscillator to the transmission line in a state where the impedance of the variable load is set so that the reflectivity of the high frequency signal in the variable load is larger than the first value. To detect
In the second step, the impedance of the variable load is changed so that the reflectivity of the high frequency signal at the variable load increases as the amplitude of the high frequency signal detected by the signal detector in the immediately preceding first step increases.
The moving object detection sensor according to any one of claims 1 to 3. 5. The moving object detection sensor according to claim 4, wherein in the second step, the impedance of the variable load is changed so that the impedance of the variable load increases as the amplitude of the high-frequency signal detected by the signal detector in the immediately preceding first step increases. Variable load
A capacitor with one terminal connected to the transmission line;
A diode whose anode is connected to the other terminal of the capacitor;
An inductor having one terminal connected to the other terminal of the capacitor and the anode of the diode;
A DC power source whose positive electrode is connected to the other terminal of the inductor, and whose negative electrode is connected to the cathode of the diode, the energization current can be changed,
With
The moving object detection sensor according to any one of claims 1 to 5.

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