Radio wave type sensor and non-contact switch

Abstract

To provide a radio wave type sensor which can be prevented from performing false detection due to unintentional action of a user.SOLUTION: The present disclosure provides a radio wave type sensor 10 which comprises: a transmission antenna 11 transmitting a radio wave; a reception antenna 12 receiving the radio wave reflected from an object; and a detection determination unit 165 which detects the object moving at a prescribed speed in a direction approaching or seceding from the antenna by means of a relationship between a pre-set Doppler signal frequency and Doppler signal frequency of the object moving at a prescribed speed with respect to the antenna.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present disclosure relates to a non-contact proximity switch that employs a radio wave sensor and that suppresses erroneous detection and controls equipment in a non-contact manner. [Background technology]

[0002] Conventionally, non-contact switches using infrared rays, light, etc. have been widely known. Also, Patent Document 1 discloses a non-contact switch using radio waves. In the non-contact switch of Patent Document 1, when an object (hand or finger) is located within a predetermined range from a sensor, the non-contact switch detects the object (hand or finger) and starts or stops a predetermined function of a device connected to the non-contact switch.

[0003] In addition, in the non-contact switch of Patent Document 1, when an object is detected by a first sensor and then by a second sensor, the movement of the object (hand or finger) from the first sensor to the second sensor is detected as an operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-131450 A Summary of the Invention [Problem to be solved by the invention]

[0005] The non-contact switch of Patent Document 1 detects a pedestrian as an object simply by entering within a predetermined range from the sensor, and detects a pedestrian walking within the predetermined range from the sensor as an operation by the user. For this reason, the non-contact switch of Patent Document 1 may cause erroneous detection due to an unintended operation by the user.

[0006] In order to solve the above problems, an object of the present disclosure is to provide a radio wave sensor capable of preventing erroneous detection due to unintended actions by a user. [Means for solving the problem]

[0007] In order to achieve the above object, the radio wave sensor disclosed herein employs a method of detecting an object moving toward or away from an antenna based on a preset frequency of a Doppler signal.

[0008] Specifically, the radio wave sensor of the present disclosure includes: an antenna for transmitting radio waves and receiving the radio waves reflected by an object; The present invention is characterized by comprising a detection and determination unit that detects an object moving toward or away from the antenna based on the relationship between a predetermined Doppler signal frequency and the Doppler frequency of the object moving relative to the antenna.

[0009] With this configuration, it is possible to detect an object moving toward or away from the antenna at a specified Doppler frequency based on a preset frequency of a Doppler signal, while also suppressing erroneous detection of other objects.

[0010] In addition, the radio wave sensor: a phase detector that outputs two signals that are 90 degrees out of phase with each other based on a signal from the antenna; an integrating unit that calculates a product of a signal obtained by shifting one of the two signals in time by a period corresponding to the 90-degree phase at the frequency of the set Doppler signal and the other signal, The detection determination unit may detect the object moving toward or away from the antenna based on the product.

[0011] With this configuration, signals from objects moving relative to the antenna at Doppler frequencies close to the frequency of the set Doppler signal are emphasized, while sensitivity to objects moving at frequencies away from the frequency of the set Doppler signal is reduced, thereby reducing erroneous detections.

[0012] The frequency of the set Doppler signal may be set so that the corresponding Doppler velocity is any value between 2 m / s and 10 m / s.

[0013] According to this configuration, when the detection target is a user's action of waving their hand in a direction approaching the antenna, the action can be suitably detected and false detection can be suppressed. Specifically, the speed of a user's action of waving their hand in a direction approaching or moving away from the antenna is usually about 2 m / s, which is more than twice as fast as the speed of other parts of the body or, for example, a pedestrian approaching the radio wave sensor, which is about 1 m / s. Therefore, by setting the Doppler center velocity to 2 m / s or more, false detection can be suppressed.

[0014] Also, a moving average unit that calculates a moving average of the product is provided, The object moving toward or away from the antenna may be detected based on the fact that the greater the difference between the frequency of the Doppler signal and the Doppler frequency of the object relative to the antenna, the smaller the absolute value of the calculation result by the moving average unit.

[0015] According to this configuration, when the detection target is a user's waving motion in a direction toward or away from the sensor, the motion can be suitably detected. Also, false detection of an object with a low Doppler frequency, such as body swaying, can be prevented.

[0016] The moving average may be a moving average of the product at every time interval between 20 ms and 1 s.

[0017] According to this configuration, when the detection target is a user's waving motion in a direction toward or away from the sensor, the motion can be suitably detected. Also, false detection of an object with a low Doppler frequency, such as body swaying, can be prevented.

[0018] Also, a motion of the user waving their hand in a direction approaching the antenna may be detected.

[0019] The above-mentioned radio wave sensor and The hand waving motion may further include a counter that outputs information indicating that a hand waving motion has occurred when the hand waving motion is detected a predetermined number of times within a predetermined time period.

[0020] With this configuration, it is possible to prevent malfunction of the device caused by the radio wave sensor detecting an object that has come close to the radio wave sensor unintentionally by the user.

[0021] an A / D converter that converts an output of the phase detector into a digital signal; The digital signal processing device may further include a first signal removal unit that sets an upper threshold or a lower threshold for removing large signals caused by sudden noise, and when output data from the A / D converter falls below the upper threshold or the lower threshold, replaces the output data with 0 and outputs the two signals to the accumulator.

[0022] According to this configuration, it is possible to remove the influence of sudden noise before causing the integrating section and the moving average section to execute processing.

[0023] Also, a short-time moving average unit that performs moving average calculations in a short time; and a spike removal unit which determines a signal to be a spike signal when the value of the short-time moving average is equal to or less than a predetermined positive threshold and exceeds a threshold range equal to or greater than a negative threshold a predetermined number of times or less, and replaces the spike signal with a signal having a value within the threshold range.

[0024] According to such a configuration, the spikes remaining after the large signal removal by the first signal removal section are effectively removed, and the movement of the target object to be detected is reliably detected.

[0025] The above disclosures may be combined to the greatest extent possible. Effect of the Invention

[0026] According to the radio wave sensor of the present disclosure, it is possible to prevent erroneous detection due to unintended actions by the user. [Brief description of the drawings]

[0027] [Figure 1] 1 is a diagram illustrating a configuration of a microwave Doppler detection device according to a first embodiment of the present disclosure. [Diagram 2] 2A to 2C are diagrams illustrating an overview of signal processing of the radio wave sensor according to the first embodiment of the present disclosure. [Diagram 3] 1 is a diagram illustrating a configuration of a signal processing circuit according to a first embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram illustrating a Doppler signal before integration processing and moving average processing are performed. [Diagram 5] FIG. 13 is a diagram illustrating a Doppler signal after time shift processing. [Figure 6] FIG. 11 is a diagram illustrating a Doppler signal after integration processing. [Figure 7] FIG. 11 is a diagram illustrating a Doppler signal after moving average processing. [Figure 8] FIG. 1 is a diagram illustrating how sensitivity decreases as the Doppler velocity of an object moves away from the Doppler center velocity. [Figure 9] FIG. 13 is a diagram illustrating a situation in which a person crosses in front of a sensor. [Figure 10] 10 is a diagram illustrating the Doppler velocity when an object passes in front of a sensor. FIG. [Figure 11] 11 is a diagram illustrating the actual measured value of Doppler velocity when a hand is waved toward a sensor. FIG. [Figure 12] 11 is a diagram illustrating the actual measured values ​​of Doppler velocity when a hand is waved from side to side in front of a sensor. FIG. [Figure 13] FIG. 13 is a diagram illustrating the effect of the present disclosure. [Figure 14] FIG. 11 is a diagram illustrating a configuration of a signal processing circuit according to a second embodiment of the present disclosure.

[0028] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings are assumed to indicate the same components.

[0029] (Embodiment 1) A microwave Doppler detection device 100 according to an embodiment of the present disclosure will be described with reference to FIGS.

[0030] [Outline of microwave Doppler detection device] FIG. 1 is a diagram illustrating the configuration of a microwave Doppler detection device 100. As shown in FIG. The microwave Doppler detection device 100 is a device that transmits microwaves, detects the reflected waves from a measurement object, and outputs a detection signal corresponding to the position and movement of the measurement object. The microwave Doppler detection device 100 is connected to an external device, and the external device functions based on the detection signal from the microwave Doppler detection device 100. The microwave Doppler detection device 100 functions as a non-contact switch.

[0031] The microwave Doppler detection device 100 includes a radio wave sensor 10 and a counter 20. The radio wave sensor 10 includes a transmitting antenna 11, a receiving antenna 12, an oscillator 13, a phase detector 14, an AD converter (A / D converter (Analog Digital Converter)) 15, and a signal processing circuit 16. The transmitting antenna 11 and the receiving antenna 12 function as "antennas."

[0032] The microwave Doppler detection device 100 according to the present embodiment is configured to detect a user's hand waving action in a direction approaching or moving away from the radio wave sensor 10, and cause an external device to function. In particular, in the following description, the user's hand waving action in a direction approaching the radio wave sensor 10 may be referred to as a "vertical wave". In addition, the user's hand waving action parallel to the sensor surface of the radio wave sensor 10 may be referred to as a "horizontal wave". Note that the scope of the present disclosure is not limited to the microwave Doppler detection device detecting the user's vertical wave, and the microwave Doppler detection device is capable of detecting various user actions, and is also capable of detecting the actions of objects other than the actions of a human body.

[0033] The radio wave sensor 10 is a Doppler sensor, and can detect the presence of a moving object based on the speed of the object relative to the radio wave sensor 10 and the presence or absence of a Doppler signal. The transmitting antenna 11 transmits microwaves to the outside. Specifically, a signal oscillated by an oscillator 13 is transmitted from the transmitting antenna 11 as a transmission wave. The transmission wave from the transmitting antenna 11 is reflected by the object. The receiving antenna 12 receives the reflected wave reflected by the object.

[0034] The oscillator 13 outputs a part of the oscillating signal to the phase detector 14 as a receiving-side local signal. The receiving-side local signal is divided into two signals so that a phase difference of 90 degrees can be obtained between the outputs. In addition, a signal related to the reflected wave received by the receiving antenna 12 is also input to the phase detector 14. Here, the phase difference between the transmitted wave and the reflected wave becomes a Doppler frequency according to the moving speed of the target object. The phase detector 14 detects the phase of the signal related to the reflected wave with the receiving-side local signal, and outputs it as two Doppler I and Q signals with a phase difference of 90 degrees. The phase detector 14 in this embodiment is a quadrature detection circuit for outputting two Doppler I and Q signals with a phase difference of 90 degrees, but the phase detector 14 does not necessarily have to be a circuit as long as it is configured to output I and Q signals with a phase difference of 90 degrees.

[0035] In this embodiment, it is possible to perform processing corresponding to the moving speed of the object from the frequency (Doppler frequency) of the Doppler I and Q signals output from the phase detector 14. In addition, the phase state of the Doppler I and Q signals changes depending on the reflection state (approaching or moving away). This makes it possible to identify whether the moving direction of the object relative to the radio wave sensor 10 is approaching or moving away.

[0036] Here, the correspondence relationship between the Doppler frequency from an object and the moving speed of the object will be explained. The Doppler frequency fd when the object is moving is expressed by the following formula.

number

[0037] Where: fd: Doppler frequency (Hz) v: object's moving speed (m / s) f0: Transmission wave frequency (Hz) c: Speed ​​of light 3×10^8(m / s) θ: the angle between the direction of movement of the object and the direction of observation For example, when the transmission frequency f0 is 24.15 GHz, the Doppler frequency fd of an object with a speed v of 2 m / s is 322 Hz, and the Doppler frequency fd of an object with a speed v of 3 m / s is 483 Hz.

[0038] In this way, since a predetermined relationship exists between the moving speed v (Doppler speed: vcosθ) of the object and the Doppler frequency fd, the radio wave sensor 10 can execute processing according to the moving speed of the object.

[0039] The Doppler I and Q signals output by the phase detector 14 are input to an AD converter 15. The AD converter 15 converts the Doppler I and Q signals into AD signals and outputs them to a signal processing circuit 16. The signal processing circuit 16 performs predetermined processing and outputs the detection result of the object as a detection signal. The detailed configuration and processing of the signal processing circuit 16 will be described later.

[0040] The counter 20 counts the number of detection signals from the signal processing circuit within a predetermined time. The counter 20 functions as a filter that outputs a detection signal from the radio wave sensor 10 to an external device when the number of detections within the predetermined time exceeds a predetermined number. The predetermined time and the predetermined number of times as thresholds for the counter 20 to output a detection signal to an external device can be set arbitrarily by the user. By interposing the counter 20 between the radio wave sensor 10 and the external device, it is possible to suppress malfunction of the device caused by the radio wave sensor 10 detecting an object unintentionally approaching the radio wave sensor 10 by the user.

[0041] Note that whether or not to interpose the counter 20 between the radio wave sensor 10 and the external device is optional, and can be selected by the user depending on the characteristics of the external device. Fig. 1 also shows both a case where the radio wave sensor 10 outputs a detection signal directly to the external device, and a case where the detection signal is output to the external device via the counter 20.

[0042] [Signal processing of radio wave sensor 10] Next, an overview of the signal processing of the radio wave sensor 10 will be described with reference to FIG. 2. FIG. 2 is a diagram for explaining an overview of the signal processing of the radio wave sensor 10. The radio wave sensor 10 includes a Doppler sensor circuit unit 101, a pair of high-pass filters 17A and 17B, a pair of amplifiers 18A and 18B, a pair of AD converters 15A and 15B, and a signal processing circuit 16 as a configuration for signal processing. The Doppler sensor circuit unit 101 includes the above-mentioned transmitting antenna 11, receiving antenna 12, and phase detector 14. As described above, the phase detector 14 outputs two Doppler I and Q signals that are 90 degrees out of phase. Specifically, the Doppler I signal is input to the high-pass filter 17A, and the Doppler Q signal is input to the high-pass filter 17B. Thus, in this embodiment, two high-pass filters 17, two amplifiers 18, and two AD converters 15 are provided corresponding to the Doppler I and Q signals.

[0043] The pair of high-pass filters 17A and 17B attenuate low frequencies corresponding to small movements. In this embodiment, the cutoff frequency of the pair of high-pass filters 17A and 17B is set to the Doppler center frequency, and the pair of high-pass filters 17A and 17B function to cut off low frequencies equal to or lower than the Doppler center frequency. In this embodiment, the low-pass frequency of the pair of high-pass filters 17A and 17B is set to, for example, about 50 Hz. The pair of high-pass filters 17A and 17B output the filtered Doppler I and Q signals to the pair of amplifiers 18A and 18B.

[0044] The pair of amplifiers 18A and 18B amplify the Doppler I and Q signals from which the low frequency range has been removed by the pair of high pass filters 17A and 17B. The pair of amplifiers 18A and 18B output the amplified Doppler I and Q signals to the pair of AD converters 15A and 15B.

[0045] The pair of AD converters 15A and 15B samples the amplified Doppler I and Q signals at a sampling time of, for example, 1 / 8 period of the Doppler center frequency or less. The pair of AD converters 15A and 15B outputs the sampled Doppler I and Q signals to the signal processing circuit 16.

[0046] Next, the detailed configuration and processing of the signal processing circuit 16 will be described with reference to Fig. 3. Fig. 3 is a diagram for explaining the configuration of the signal processing circuit 16. The signal processing circuit 16 includes a pair of signal removal units 161A and 161B, a pair of memories 162A and 162B, an integrator 163, a moving average unit 164, and a detection determination unit 165. In this embodiment, two signal removal units 161 and two memories 162 are provided corresponding to the Doppler I and Q signals. The pair of signal removal units 161A and 161B function as a "first signal removal unit."

[0047] Specifically, the radio wave sensor 10 of the present disclosure includes: A transmitting antenna 11 for transmitting radio waves, and a receiving antenna 12 for receiving radio waves reflected by an object, The system includes a detection and determination unit 165 that detects an object moving toward or away from the antenna at a predetermined speed based on the relationship between a preset Doppler signal frequency and the Doppler frequency of the object moving relative to the antenna.

[0048] The outputs from the pair of AD converters 15A and 15B are input to a pair of signal removal units 161A and 161B. The pair of signal removal units 161A and 161B remove signals that exceed a positive upper threshold and signals that fall below a negative lower threshold. The upper threshold or lower threshold is set to a value that is smaller than the value at which the amplifier 18 or the AD converter 15 saturates, or the maximum value of the AD converter, but is sufficiently larger than the value of the detection signal from the object to be measured. Specifically, when there is a signal that exceeds the upper threshold and a signal that falls below the lower threshold, the output data of that portion is replaced with 0. In this way, the signal removal unit 161 functions to remove the influence of large noise, such as a single shot and saturation of AD conversion, before performing the integration process and moving average process described later. The outputs from the pair of signal removal units 161A and 161B are input to a pair of memories 162A and 162B.

[0049] In addition to or instead of the above-mentioned high-pass filter 17, a digital filter that cuts off frequencies lower than the Doppler center frequency may be provided before or after signal removal by the signal removal unit 161 after AD conversion by the AD converter 15. This makes it possible to remove noise and unintended operations and reduce malfunctions.

[0050] A pair of memories 162A and 162B stores, as data strings for a predetermined period of time, time series (plural) data for each time period corresponding to approximately ¼ period of the Doppler center frequency for each of the sampled Doppler I and Q signals.

[0051] The integrating unit 163 executes an integration process of the Doppler I and Q signals based on the data strings stored in the pair of memories 162A and 162B. The integrating unit 163 passes the data after the integration process to the moving average unit 164. The details of the integration process will be described later. The moving average unit 164 calculates the average value of the data from the current time to a certain time ago based on the data after the integration process (moving average process), and stores these as a data array for the certain time. The details of the moving average process will be described later.

[0052] The detection and determination unit 165 determines whether or not movement of an object has been detected based on the data sequence stored in the moving average unit 164. When the detection and determination unit 165 determines that movement of an object has been detected, it outputs a detection signal.

[0053] Next, the integration process by the integration unit 163 and the moving average process by the moving average unit 164 will be described in detail with reference to FIGS. First, the Doppler I and Q signals before each processing will be described. Fig. 4 is a diagram for explaining the Doppler I and Q signals before integration processing and moving average processing. Fig. 4 shows the relationship between the Doppler I and Q signals when an object makes a predetermined movement that is the subject of detection. In other words, Fig. 4 shows the relationship between the Doppler I and Q signals when an object moves at the Doppler central frequency (= central velocity). As shown in the figure, the Q signal shows a phase delay of 90 degrees with respect to the I signal, and the I and Q signals have similar shapes.

[0054] [Accumulation processing] When performing the integration process, as shown in Fig. 5, the integration unit 163 shifts the waveform of either the I signal or the Q signal in time by 1 / 4 cycle of the set Doppler center frequency (time shift process). Fig. 5 is a diagram explaining the Doppler I and Q signals after the time shift process. Fig. 5 shows a situation in which the phase of the Q signal is shifted by 90 degrees and the Q signal and the I signal are almost overlapped. In other words, Fig. 5 shows a situation in which the phases of the Q signal and the I signal are almost the same. Note that the waveform of either the I signal or the Q signal may be shifted in time by 1 / 4 cycle of the set Doppler center frequency so that the phases of the I signal and the Q signal differ by 180 degrees.

[0055] The integrating unit 163 calculates the product of the I signal and the Q signal after the time shift processing. FIG. 6 is a diagram for explaining the Doppler I and Q signals after the integration processing. Since the I signal and the Q signal overlap as a result of the time shift processing, the product value is always a positive value. In this way, the integrating unit 163 emphasizes the reflected wave from the target moving at the Doppler center frequency (= center speed) set by the integration processing. Note that if either the I signal or the Q signal is shifted so that the phases of the I signal and the Q signal differ by 180 degrees, the product value is always a negative value.

[0056] Here, the Doppler central frequency (Doppler central velocity) can be arbitrarily set by the user and is stored in the signal processing circuit 16. The Doppler central frequency is an example of the "preset frequency of the Doppler signal". The Doppler central velocity is an example of the Doppler velocity corresponding to the preset frequency of the Doppler signal. When the radio wave sensor 10 is used as a switch for operating an external device, the Doppler central velocity may be set to a value sufficiently larger than the walking speed of a pedestrian, etc., so as not to erroneously detect the walking speed of a pedestrian, which is generally about 1 m / s. On the other hand, when operating an external device by vertical swing, the speed of such a movement is generally about 2 m / s, so the Doppler central velocity may be set to 2 m / s or more. In this embodiment, the signal from an object moving at a speed close to the set Doppler central velocity is emphasized, while the sensitivity to an object moving at a speed far from the Doppler central velocity is reduced, so that erroneous detection can be suppressed. In this embodiment, the Doppler central velocity is set to 2 m / s. As a specific example of use, the Doppler central velocity may be set in the range of 2 m / s to 10 m / s. If the Doppler central velocity is set to a value greater than 2 m / s, for example, 4 m / s, the sensitivity to vertical swings itself decreases. However, from the standpoint of detecting vertical swings and suppressing erroneous detection of objects moving at a speed slower than vertical swings, the difference in sensitivity is important, and this can be addressed by changing the detection threshold of the radio wave sensor 10. In other words, even in this case, it is possible to distinguish and detect vertical swings from other movements.

[0057] [Moving average processing] The moving average unit 164 calculates the average value of data from the current time to a fixed time ago based on the data after the integration process (moving average process). Fig. 7 is a diagram explaining the Doppler I and Q signals after moving average process. If the direction of movement changes in a time shorter than the set moving average time, the plus and minus of the signal are inverted, so they are offset by averaging and the intensity becomes smaller. In other words, signals that are not moving in a fixed direction, noise, etc. are removed by moving average process.

[0058] In a vertical swing at 2 m / s, the hand moves about 4 cm in 20 ms, and in a vertical swing at 3 m / s, the hand moves about 6 cm in 20 ms. When the average moving time is set to about 20 ms, if the hand is waving in a direction approaching the radio wave sensor 10 for 4 to 6 cm or more, the detection signal becomes large, and the sensor is less likely to react to small movements such as waving the hand sideways (horizontal swing) or shaking in front of the radio wave sensor 10, reducing malfunctions. The average moving time can be set arbitrarily by the user and is stored in the signal processing circuit 16. When an external device is operated by a vertical swing, such an operation generally continues for 20 ms or more, so the average moving time may be set to 20 ms or more. In this embodiment, the average moving time is set to 20 ms. As a specific example of use, the average moving time may be set in the range of 20 ms to 1 s.

[0059] In addition, because the phase of the I and Q signals differs by 180 degrees when the target is approaching or moving away, the plus and minus of the integration process result are inverted. This makes it possible to simultaneously determine whether the target is approaching or moving away.

[0060] [Sensitivity of radio wave sensor] Next, with reference to Fig. 8, suppression of detection of movement at frequencies lower than the set Doppler center frequency will be described in detail. In other words, suppression of detection of movement at velocities lower than the set Doppler center velocity will be described in detail. Fig. 8 is a diagram for explaining that the sensitivity decreases as the object velocity moves away from the Doppler center velocity. Fig. 8 shows an example in which the Doppler center velocity is set to 1.5 m / s (Doppler center frequency = 241.5 Hz).

[0061] As described above, in this embodiment, the integrating unit 163 and the moving average unit 164 emphasize the reflected waves from an object that is continuously moving for at least the moving average time around the set Doppler center frequency (= center velocity). Therefore, as shown in Fig. 8, the signal (output voltage) detected by the signal processing circuit 16 becomes smaller as the object's velocity deviates from 1.5 m / s (Doppler center velocity). Therefore, by using an arbitrary output voltage value as a threshold, it is possible to remove micro-vibrations and external noise below a predetermined speed.

[0062] For example, the speed of a pedestrian is generally about 1 m / s (3.6 km per hour), and when the transmission frequency f0 is 24.15 GHz, the Doppler frequency fd caused by the pedestrian walking is 161 Hz. However, when a pedestrian walks toward (close to) the radio wave sensor 10, the pedestrian must stop in front of the radio wave sensor 10, and therefore the pedestrian's speed is usually slower than 1 m / s. In other words, the Doppler frequency fd caused by the pedestrian walking is sufficiently smaller than the Doppler center frequency, which prevents erroneous detection of noise caused by the pedestrian walking.

[0063] [About movement across a radio wave sensor] Next, suppression of detection of movement (motion) passing by the radio wave sensor 10 will be described in detail with reference to Fig. 9 and Fig. 10. Fig. 9 is a diagram explaining a person passing in front of the radio wave sensor 10. Fig. 10 is a diagram explaining the Doppler velocity when an object passes in front of the sensor.

[0064] 9, assume that a person crosses in front of the radio wave sensor 10 at a speed of 1.5 m / s parallel to the sensor surface of the radio wave sensor 10. Here, d is the distance between the sensor surface and the person when the person comes in front of the radio wave sensor 10.

[0065] 10, even when a moving object passes in front of the radio wave sensor 10 at the same speed of 1.5 m / s, the Doppler speed actually observed by the radio wave sensor 10 changes according to the distance d. This is because the angle θ between the moving direction of the moving object relative to the radio wave sensor 10 and the direction observed by the radio wave sensor 10 changes according to the distance d and the position (direction) of the moving object relative to the front of the radio wave sensor 10. For example, the angle θ in front of the radio wave sensor 10 is 90 degrees and the Doppler frequency fd is 0 Hz.

[0066] 10, it can be seen that the further a moving object is from the radio wave sensor 10, the smaller the Doppler velocity (Doppler frequency) actually observed by the radio wave sensor 10. For this reason, even if a moving object, such as an automobile or bicycle, that moves faster in absolute terms than the set Doppler center velocity passes (crosses) in front of the radio wave sensor 10, the Doppler velocity actually observed by the radio wave sensor 10 will be sufficiently smaller than the Doppler center velocity, and erroneous detection can be suppressed.

[0067] [Comparison of actual vertical and horizontal swing measurements] Next, referring to Figs. 11 and 12, the actual measured values ​​when the hand is moved in a direction approaching the radio wave sensor 10 (vertical swing) and when the hand is swung sideways relative to the radio wave sensor 10 (horizontal swing) are compared. Fig. 11 shows the actual measured Doppler velocity for vertical swing. Fig. 12 shows the actual measured Doppler velocity for horizontal swing. In the following explanation, it is assumed that the Doppler central velocity is set to 2 m / s so as not to erroneously detect movements other than vertical swing. Note that Figs. 11 and 12 show the waveform of the output voltage (signal) approximately in the center, and the Doppler velocity is shown below that.

[0068] When a person swings their hand vertically, they can move their hand like a whip around their wrist, so that the hand moves close to the radio wave sensor 10 at a relatively high speed of 2 m / s or more. In this case, the hand moves toward the sensor surface, so that the direction of the hand movement coincides with the direction observed by the radio wave sensor 10. Therefore, as shown in FIG. 11, when the user swings their hand close to the radio wave sensor 10 (see (i) in the figure), the number of waves required for detection can be obtained sufficiently. In addition, since the speed of a vertical swing is more than twice as fast as the walking speed of a person (1 m / s), erroneous detection can be suppressed by setting the Doppler center speed to 2 m / s or more. Furthermore, since the time that the hand approaches the radio wave sensor 10 due to a vertical swing usually continues for 20 ms or more, erroneous detection due to sudden movements of a person or object can be suppressed by setting the moving average time to 20 ms or more. In particular, by setting the moving average time to 20 ms or more, erroneous detection of objects with low Doppler frequencies, such as body swaying, can be prevented, and the detection is further specialized for vertical swing movements.

[0069] More specifically, in this embodiment, as described above, a threshold value for the output voltage (signal) is set, and the threshold value is compared with the average value of the actual output voltage to detect vertical swing and prevent erroneous detection of other movements. The threshold value is set based on the characteristics of the radio wave sensor 10, and can be arbitrarily determined to be a value between a signal that is desired to be acquired and a signal that is not desired to be acquired.

[0070] As shown in (ii) of FIG. 11, the user gradually slows down the movement of the hand approaching the sensor surface in order to stop the action of bringing the hand close in front of the radio wave sensor 10. This reduces the number of waves that can be acquired. Also, when the user brings the hand close to the sensor surface of the radio wave sensor 10 and then moves the hand away from the sensor surface, the Doppler velocity is smaller than when the hand is brought close due to the structure of the human wrist, etc. This reduces the number of waves that can be acquired. As a result, it is possible to eliminate the detection of the actions shown in (ii) and (iii) of the figure, and various functions can be realized based on the vertical swing action of bringing the hand close to the radio wave sensor 10 in (i).

[0071] For example, when a predetermined number of vertical swings (movement of approaching the sensor surface) are detected within a predetermined time, the radio wave sensor 10 may output a detection signal to cause an external device to function. Such a configuration may be achieved by the above-mentioned counter 20, or may be achieved by a counter that the signal processing circuit 16 is provided with independently. For example, when the predetermined time and the predetermined number of times are three or more vertical swings detected within 0.5 seconds, the signal processing circuit 16 may output a detection signal. Also, various functions can be realized according to the number of detections within such a predetermined time. For example, when the radio wave sensor 10 is applied to an automatic door, it is possible to open or close the door, stop the operation of the door in the middle of opening or closing, or lock the operation according to the number of detections.

[0072] On the other hand, as shown in Fig. 12, when the moving object swings sideways across the front of the radio wave sensor 10, the Doppler velocity is smaller. However, even when the moving object swings sideways, there is a risk that an output voltage greater than the threshold value will be detected due to the short distance between the sensor surface and the moving object. However, due to the antenna characteristics of the radio wave sensor 10, the closer the distance to the sensor surface, the smaller the detection range becomes, and the fewer waves are required for detection. This makes it possible to prevent erroneous detection.

[0073] Also, measures can be considered for fast-moving cars and motorcycles, but if the movement direction is crossing the sensor, the Doppler velocity decreases the farther away from the sensor, and even if a vehicle passes a position 10 m away from the radio wave sensor 10 at a speed of about 50 km / h, the speed seen from the radio wave sensor 10 will be 1 m / s or less. For this reason, it is possible to suppress erroneous detection by setting the Doppler center velocity to 2 m / s.

[0074] [effect] Next, the effects of the radio wave sensor 10 will be described with reference to Fig. 13. Fig. 13 is a diagram for explaining the effects of the radio wave sensor 10.

[0075] First, according to this embodiment, (A) a rather fast approaching motion of the hand caused by a vertical swing of the user can be suitably detected. Specifically, while a normal vertical swing motion continues for 20 ms or more at a speed of 2 m / s or more, in this embodiment, the Doppler central velocity is set to 2 m / s and the moving average velocity is set to 20 ms, so that the vertical swing motion can be suitably detected. As described above, it is sufficient that the Doppler central velocity is set to 2 m / s or more and the moving average time is set to 20 ms or more.

[0076] Furthermore, as described above, according to this embodiment, (B) the counter 20 is provided, and various functions can be realized depending on the number of detections within a predetermined time.

[0077] Furthermore, according to this embodiment, (C) false detections due to actions other than the user's vertical swing can be suitably suppressed. Specifically, for all of the following actions (1) to (4), the Doppler velocities actually observed by the radio wave sensor 10 are sufficiently smaller than the set Doppler center velocity, so false detections of these actions can be suppressed. (1) Horizontal swing just before the sensor (2) Slow movement just in front of the sensor (3) Pedestrians crossing the street near the sensor (4) Bicycles, etc. passing near the sensor As described above, due to the antenna characteristics of the radio wave sensor 10, the closer the distance to the sensor surface, the smaller the detection range becomes, and the fewer the number of waves required for detection becomes. Therefore, from this viewpoint as well, it is possible to prevent erroneous detection of the above operations (1) to (4).

[0078] (Embodiment 2)

[0079] Next, a radio wave sensor according to a second embodiment will be described with reference to Fig. 14. Fig. 14 is a diagram illustrating the configuration of a signal processing circuit 27 according to the second embodiment. The signal processing circuit 27 performs short-time moving average processing and spike removal processing.

[0080] The signal processing circuit 27 includes a signal removal unit 161, a memory 162, an accumulator 163, and a detection and determination unit 165, similar to the signal processing circuit 16 according to the first embodiment. The signal processing circuit 27 also includes a moving average unit 263 instead of the moving average unit 164, and includes a short-time moving average unit 261 and a spike determination and removal unit 262 between the accumulator 163 and the moving average unit 263.

[0081] The short-time moving average unit 261 calculates the average value of data for a short time interval (from the current time interval to a certain time ago), for example, several milliseconds (msec) to several tens of milliseconds, and stores these as a data array for a certain time. The spike determination and removal unit 262 extracts data (signals) from the array data that continuously exceed a threshold range that is equal to or less than a certain positive threshold and equal to or more than a negative threshold a certain number of times or less as spikes, and replaces the continuous signals that exceed the certain number of times with a value in the threshold range, for example, 0. For example, if the short-time moving average calculation is performed every 30 msec in a time range from 100 to 500 msec, the spike determination and removal unit 262 executes spike determination with the predetermined number of times being about 10.

[0082] The moving average section 263 calculates the average value of data from the current time to a certain time ago (a time interval longer than the above-mentioned short time interval) for the signal (data sequence) output from the spike determination and removal section 262.

[0083] According to such spike determination and removal, spikes remaining after the large signal removal by the signal removal unit 161 are effectively removed, and the vertical shaking that is desired to be detected is reliably detected.

[0084] The device of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network. The program of the present disclosure is a program for causing a computer to realize each function of the device according to the present disclosure, and is a program for causing a computer to execute each procedure of the method executed by the device according to the present disclosure. [Explanation of symbols]

[0085] 10: Radio wave sensor 11: Transmitting antenna 12: Receiving antenna 13: Oscillator 14: Phase detector 15, 15A, 15B: AD converter 16, 27: Signal processing circuit 161A, 161B: Signal removal section 162A, 162B: Memory 163: Integration section 164, 263: Moving average part 165: Detection and judgment unit 261: Short-term moving average part 262: Spike detection and removal unit 17A, 17B: High pass filter 18A, 18B: Amplifier 20: Counter 100: Microwave Doppler detector 101: Doppler sensor circuit section

Claims

1. an antenna for transmitting radio waves and receiving the radio waves reflected by an object; a detection and determination unit that detects the object moving at a predetermined speed in a direction approaching or moving away from the antenna based on a relationship between a preset frequency of a Doppler signal and a Doppler frequency of the object moving relative to the antenna, Radio wave sensor.

2. a phase detector that outputs two signals having a phase difference of 90 degrees based on a signal from the antenna; an integrating unit that calculates a product of a signal obtained by shifting one of the two signals in time by a period corresponding to the 90-degree phase at the frequency of the set Doppler signal and the other signal, The detection determination unit detects the object moving in a direction approaching or moving away from the antenna based on the product. The radio wave sensor according to claim 1 .

3. The frequency of the set Doppler signal is set so that the corresponding Doppler velocity is any value between 2 m / s and 10 m / s. The radio wave sensor according to claim 2.

4. A moving average unit that calculates a moving average of the product, detecting the object moving toward or away from the antenna based on the fact that the absolute value of the result of the calculation by the moving average unit becomes smaller as the difference between the frequency of the Doppler signal and the Doppler frequency of the object relative to the antenna becomes larger; The radio wave sensor according to claim 2.

5. The moving average is a moving average of the product at every time interval of 20 ms or more and 1 s or less.

5. The radio wave sensor according to claim 4.

6. Detecting a user's hand waving action in a direction approaching the antenna; The radio wave sensor according to claim 1 .

7. The radio wave sensor according to claim 6 , a counter that outputs information indicating that the hand waving motion has been performed when the hand waving motion has been detected a predetermined number of times within a predetermined time period. Non-contact switch.

8. an A / D converter that converts an output of the phase detector into a digital signal; a first signal removal unit that sets an upper threshold or a lower threshold for removing a large signal caused by sudden noise, and when output data from the A / D converter falls below the upper threshold or the lower threshold, replaces the output data with 0 and outputs the two signals to the integrating unit. The radio wave sensor according to claim 2 .

9. A short-time moving average unit that performs moving average calculations in a short time; a spike removal unit that determines a signal as a spike signal when the value of the short-time moving average is equal to or smaller than a predetermined positive threshold and exceeds a threshold range equal to or larger than a negative threshold a predetermined number of times or less, and replaces the spike signal with a signal having a value within the threshold range. The radio wave sensor according to claim 8.

Images