Detection device and detection system

Abstract

To provide a detection device that can improve detection accuracy.SOLUTION: A detection device 100 includes: a first sensor that transmits a first electromagnetic wave to a first range 51a and receives the first electromagnetic wave reflected in the first range; a second sensor that transmits a second electromagnetic wave to a second range 51b, which is different from the first range, and receives the second electromagnetic wave reflected in the second range; and a processing unit that calculates information about an object that has reflected the first and second electromagnetic waves based on a first signal output by the first sensor and a second signal output by the second sensor.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a detection device and a detection system. [Background technology]

[0002] There is known an apparatus for detecting biological information of a passenger or the like who is in a vehicle. When a radar sensor is used as a sensor for detecting biological information, it is known that the biological information is detected by using an output signal of the radar sensor and an output signal of a vibration sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 075467 [Patent Document 2] Special Publication No. 2020-531063 [Patent Document 3] Patent Publication No. 2022-25732 [Patent Document 4] JP 2020-74805 A [Patent Document 5] JP 2017-131445 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when detecting information about passengers on a vehicle using a radar sensor, noise caused by vibrations of the vehicle can be removed to a certain degree by using the output signal of the radar sensor in combination with the output signal of a vibration sensor provided on the vehicle. However, while this method can detect vibrations of the vehicle, it cannot accurately detect vibrations of passengers who are affected by the vibrations of the vehicle. For this reason, noise cannot be sufficiently removed, and the detection accuracy of information about passengers decreases.

[0005] The present invention has been made in consideration of the above problems, and has an object to improve detection accuracy. [Means for solving the problem]

[0006] The present invention is a detection device comprising a first sensor that transmits a first electromagnetic wave to a first range and receives the first electromagnetic wave reflected in the first range, a second sensor that transmits a second electromagnetic wave to a second range different from the first range and receives the second electromagnetic wave reflected in the second range, and a processing unit that calculates information about an object that reflects the first electromagnetic wave and the second electromagnetic wave based on a first signal output by the first sensor and a second signal output by the second sensor. Effect of the Invention

[0007] According to the present invention, it is possible to improve the detection accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a detection device according to a first embodiment. [Diagram 2] FIG. 2 is a plan view of the detection device according to the first embodiment. [Diagram 3] FIG. 2 is a diagram showing the detection device according to the first embodiment when in use. [Figure 4] FIG. 2 is a voltage versus time diagram showing example signals S1a and S1b. [Diagram 5] FIG. 2 is a voltage versus time diagram showing example signals S1a and S1b. [Figure 6] 4A to 4C are diagrams illustrating the spectrum of a signal S1a and the pass characteristics of a filter. [Figure 7] FIG. 2 is a functional block diagram of a process performed by a processing unit in the first embodiment. [Figure 8] FIG. 2 shows the spectra of signals S3a, S3b and S3c. [Figure 9] 11 is a functional block diagram of another example of the processing performed by the processing unit in the first embodiment. FIG. [Figure 10]1 is a diagram showing an example in which a detection device is attached to a vehicle; [Figure 11] 1 is a diagram showing an example in which a detection device is attached to a vehicle; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A radar sensor that detects biological information using a millimeter wave radar or the like can detect biological information without contacting a living body, so there is no need to attach a cable or a sensor to the body, and the burden on the body is small. However, when detecting biological information using a radar sensor in an environment with a lot of vibration, such as inside a vehicle such as a car, train, or airplane, the influence of vibrations other than biological vibrations, such as vibrations caused by the vehicle, is large. Therefore, even if a radar sensor is used to detect the biological vibrations of a passenger, the passenger vibrates due to the vibration of the vehicle. As a result, the distance between the passenger's biological body and the radar sensor changes due to the vibration of the vehicle. Therefore, it is difficult to detect biological vibrations. As in Patent Documents 1 and 2, when vibrations other than biological vibrations are detected using a vibration sensor, the vibrations detected by the vibration sensor are different from the vibrations detected by the radar sensor, and it is difficult to accurately remove signals other than biological vibrations from the output signal of the radar sensor.

[0010] In the following embodiment, multiple radar sensors are provided to detect vibrations in different ranges of the living body, and the biological information is calculated based on the signals output from the multiple radar sensors. This makes it possible to accurately remove vibrations other than the biological vibrations.

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0012] 1 is a block diagram of a detection device according to a first embodiment. The detection device 100 includes radar sensor units 11a and 11b, a vibration sensor unit 11c, and a processing unit 30. The radar sensor unit 11a (and 11b) includes a transmitting antenna 12a (and 12b), a receiving antenna 13a (and 13b), a high-frequency circuit 16a (and 16b), an amplifier 18a (and 18b), a filter 20a (and 20b), and an A / D (Analog / Digital) converter 22a (and 22b). The vibration sensor unit 11c includes a sensor 21 and an A / D converter 22c.

[0013] In the radar sensor unit 11a (and 11b), the high-frequency circuit 16a (and 16b) includes an oscillator 14a (and 14b) and a mixer 15a (and 15b). The high-frequency circuit 16a (and 16b) also includes an amplifier and the like, but the description thereof will be omitted. The antenna 12a (and 12b) transmits a signal 56a (and 56b) generated by the oscillator 14a. The signals 56a and 56b are electromagnetic waves, such as microwaves or millimeter waves. The frequencies of the signals 56a and 56b are, for example, 10 GHz to 120 GHz, and are, for example, around 24 GHz. The antenna 13a (and 13b) receives a signal 58a (and 58b) reflected from the signal 56a (and 56b) irradiated to a living body. The mixer 15a (and 15b) mixes the signals 56a and 58a (and 56b and 58b) and outputs a converted signal. The frequency of the signal S0a (and S0b) output by the mixer 15a (and 15b) corresponds to the difference between the frequency of the signal 56a (and 56b) and the frequency of the signal 58a (and 58b). As a result, the signal S0a (and S0b) becomes an analog signal corresponding to the movement of the area irradiated with the signal 56a (and 56b).

[0014] The amplifier 18a (and 18b) amplifies the signal S0a (and S0b). The filter 20a (and 20b) is a low-pass filter, and filters signals in the amplified signal S0a (and S0b), for example, signals with a higher frequency than the biological vibration signal. The filters 20a and 20b are analog filters, and cannot completely remove signals of frequencies to be suppressed. However, by providing the filters 20a and 20b, repetitive noise in the A / D converters 22a and 22b can be suppressed. In addition, by limiting the frequency band in the signals S1a and S1b, the processing load of the processing unit 30 is reduced. The filters 20a and 20b may be digital filters. The A / D converter 22a (and 22b) converts the filtered signal S0a (and S0b) into a digital signal, signal S1a (and S1b).

[0015] It is preferable that the radar sensor units 11a and 11b have substantially the same configuration. That is, it is preferable that the output power of the signals 56a and 56b is substantially the same, and the gain of the signal from the antenna 12a to the filter 20a is substantially the same as the gain of the signal from the antenna 12b to the filter 20b. If the gains of the radar sensor units 11a and 11b are different, it is preferable to calibrate the difference in gain in advance.

[0016] The sensor 21 is a vibration sensor that detects, for example, vibration of a substrate and outputs a signal S0c. The A / D converter 22c converts the signal S0c into a digital signal S1c. At least one of an amplifier and a filter may be provided between the sensor 21 and the A / D converter 22c.

[0017] The processing unit 30 is a processor such as a CPU (Central Processing Unit) or a microcomputer, and executes detection processing in cooperation with software. The memory 24 is a non-volatile memory or a volatile memory, and stores setting conditions for detection, data in the middle of calculating information, programs, etc. The output device 26 outputs the results of processing by the processing unit 30 to an external device. The external device is, for example, a display device that displays images, an audio device that outputs sound, or a processor separate from the processing unit 30. The external device may be a higher-level application in the same processor as the processing unit 30.

[0018] FIG. 2 is a plan view of the detection device according to the first embodiment. The normal direction of the surface of the substrate 10 is the Z direction, and the side directions of the substrate 10 are the X direction and the Y direction. As shown in FIG. 2, in the detection device 100, the substrate 10 is provided with antennas 12a, 13a, 12b, and 13b and a sensor 21. The antennas 12a, 13a, 12b, and 13b each have four antennas arranged in the Y direction, for example. The antennas 12a, 13a, 12b, and 13b may each be one antenna, or may each be an antenna arranged in an array. By arranging a plurality of antennas, the directivity of the antenna can be increased. For example, a patch antenna can be used as the antenna.

[0019] The sensor 21 is, for example, an accelerometer, and detects vibration of the substrate 10. The high-frequency circuits 16a and 16b, the amplifiers 18a and 18b, the filters 20a and 20b, the A / D converters 22a, 22b and 22c, the processing unit 30, the memory 24, and the output device 26 may be provided on the front (+Z) side or the back (-Z) side of the substrate 10.

[0020] FIG. 3 is a diagram showing a state in which the detection device according to the first embodiment is used. FIG. 3 illustrates a cross section of a living body 50 such as a human body and a heart 52 viewed from the head. The antennas 12a and 13a are inclined toward the -X side from the +Z surface of the substrate 10. As a result, the center line 54a of the signal 56a transmitted by the antenna 12a is inclined toward the -X side from the Z direction. Therefore, the signal 56a is irradiated to a range 51a (left chest) on the -X side of the living body 50 where the heart 52 is located. The antenna 13a receives a signal 58a reflected in the range 51a. The antennas 12b and 13b are inclined toward the +X side from the +Z surface of the substrate 10. As a result, the center line 54b of the signal 56b transmitted by the antenna 12b is inclined toward the +X side from the Z direction. Therefore, the signal 56b is irradiated to a range 51b (right chest) on the +X side of the living body 50 where the heart 52 is located. The antenna 13b receives a signal 58b reflected in the range 51b. Furthermore, even if antennas 12a, 13a, 12b, and 13b are not inclined, the desired directivity can be obtained by mounting antennas 12a, 13a, 12b, and 13b on the main surface of substrate 10 and appropriately arranging multiple antenna patterns for each antenna.

[0021] 1, by mixing the signals 56a and 58a, the signal S0a output from the high-frequency circuit 16a becomes information about the movement of the range 51a of the living body 50. Because the range 51a is close to the heart 52, the signal S0a becomes a signal that includes the vibration of the heartbeat. By mixing the signals 56b and 58b, the signal S0b output from the high-frequency circuit 16b becomes information about the movement of the range 51b of the living body 50. Because the range 51b is far from the heart 52, the signal S0b becomes a signal that does not include the vibration of the heartbeat or has a small vibration of the heartbeat.

[0022] The frequencies of the signals 56a and 56b may be the same, but in the case where there is a possibility of interference occurring due to the signal 58a being received by the antenna 13b and the signal 58b being received by the antenna 13a, it is preferable to make the frequencies of the signals 56a and 56b different by at least the vibration frequency. Specifically, it is preferable that the frequencies of the signals 56a and 56b are different by at least several tens of MHz.

[0023] 4(a) and 4(b) are diagrams showing voltages versus time illustrating examples of signals S1a and S1b. FIG. 4(a) and FIG. 4(b) show signals for the same period T1. In signals S1a and S1b, signals with frequencies higher than those of biological vibrations are suppressed by filters 20a and 20b. As shown in FIG. 4(a), signal S1a includes signals 40 and 41. Signal 40 is a signal mainly related to vibrations of the heartbeat. Signal 41 is mainly vibrations of the biological body 50 other than the heartbeat (e.g., breathing, etc.) and vibrations of non-biological bodies (e.g., vehicles, etc.). As shown in FIG. 4(b), signal S1b includes almost no signal 40 and is mostly signal 41.

[0024] 5(a) and 5(b) are diagrams showing voltages versus time illustrating examples of signals S1a and S1b. Compared with FIG. 4(a) and FIG. 4(b), FIG. 5(a) and FIG. 5(b) are examples of cases where the directivity of the antenna is low. As shown in FIG. 5(a), similar to FIG. 4(a), the signal S1a includes a signal 40 related to the vibration of the heartbeat and a signal 41 related to vibrations other than the heartbeat. As shown in FIG. 5(b), the signal S1b includes a signal 40a related to the vibration of the heartbeat and vibrations other than the heartbeat in addition to the signal 41. In this way, when the directivity of the antenna is low, the signal S1b may include a signal related to the vibration of the heartbeat.

[0025] FIG. 6 is a diagram showing the spectrum of the signal S1a and the pass characteristic of the filter 20a. The spectrum of the signal S1a corresponds to the signal after the signal S1a is Fourier transformed. The position of the horizontal axis of the straight line extending vertically indicates the frequency of the spectrum, and the vertical height indicates the intensity of the frequency spectrum. The signal 42a is shown using a thick solid line, the signal 43a using a thick dotted line, and the signal 44a using a thin solid line. The pass characteristic 45 of the filter 20a corresponds to the frequency on the horizontal axis and the attenuation by the filter 20a on the vertical axis. That is, it is shown that the attenuation of the signal by the filter 20a is large for a signal with a small frequency for which the pass characteristic 45 is small. This is an example in which an analog filter is used as the filter 20a. Since the analog filter has low steepness at the cutoff frequency, signals with a frequency of 10 Hz or more also pass, and the attenuation increases as the frequency increases.

[0026] Signal 42a is a signal related to heartbeat vibration. Signal 43a is a signal related to respiration vibration. Signal 44a is a signal related to vibrations other than those of a living body, for example, a signal related to vehicle vibration. Examples of signal 44a include natural vibrations of springs such as suspensions in the case of a car or train, vibrations caused by air acting like a spring in the case of an aircraft, and / or natural vibrations of springs in cushions.

[0027] Each of the signals 42a and 43a includes a fundamental wave and harmonics. Therefore, there are multiple peaks in the frequency spectrum of each of the signals 42a and 43a. The frequency of the heartbeat vibration is, for example, 1 Hz to 4 Hz. Including the harmonics, the frequency of the signal 42a is, for example, 1 Hz to 15 Hz. The frequency of the respiratory vibration is, for example, 0.3 Hz to 3 Hz. Including the harmonics, the frequency of the signal 43a is, for example, 0.3 Hz to 10 Hz. The filter 20a suppresses the signal 44a with a frequency higher than 10 Hz, i.e., a frequency unrelated to the biosignal. Therefore, the higher the frequency, the smaller the frequency spectrum of the signal 44a becomes.

[0028] FIG. 7 is a functional block diagram of the processing performed by the processing unit 30 in the first embodiment. The band limiting units 31a, 31b, and 31c limit the frequency bands of the signals S1a, S1b, and S1c other than the frequency band of the biological vibration, respectively. The frequency bands of the signals 42a and 43a are, for example, 0.3 Hz to 15 Hz. Therefore, the band limiting units 31a, 31b, and 31c remove signals of frequency bands other than the frequency band of 0.2 Hz to 20 Hz, for example, from the signals S1a, S1b, and S1c. As a result, the signals S2a, S2b, and S2c output from the band limiting units 31a, 31b, and 31c are mostly signals of the frequency band of the biological vibration. In this way, by limiting the frequency bands not used in the subsequent processing, the load of the subsequent processing can be reduced. The band limiting units 31a, 31b, and 31c may not be provided.

[0029] The Fourier transform units 32a, 32b, and 32c perform Fourier transform on the signals S2a, S2b, and S2c, respectively. The Fourier transformed signals are output as signals S3a, S3b, and S3c, respectively. The Fourier transform is calculated, for example, by using the FFT (Fast Fourier Transform) method.

[0030] 8(a), 8(b), and 8(c) are diagrams showing the spectra of signals S3a, S3b, and S3c, respectively. The position of the horizontal axis of the straight line extending vertically indicates the frequency of the spectrum, and the height of the vertical direction indicates the intensity of the frequency spectrum. Signals 42a and 42b are shown using thick solid lines, signals 43a and 43b using thick dotted lines, and signals 44a, 44b, and 44c using thin solid lines.

[0031] As shown in Fig. 8(a), the band limiting unit 31a removes signals outside the band 46 from the signal S1a from the range 51a close to the heart 52 in Fig. 3. Therefore, the signal S3a is a signal having frequencies mostly within the band 46 compared to the signal S1a in Fig. 6.

[0032] As shown in Fig. 8(b), the band limiting unit 31b removes signals outside the band 46 from the signal S1b from the range 51b far from the heart 52 in Fig. 3. Therefore, the signal S3b is a signal having mostly frequencies within the band 46. In the signal S3b, the signal 42b relating to the vibration of the heartbeat is lower than in the signal S3a. This is because, as shown in Figs. 4(b) and 5(b), the signal S1b hardly contains the signal 40 relating to the vibration of the heartbeat. The signal S3b contains the signal 43b relating to the vibration of breathing and the signal 44b relating to the vibration of non-living things to the same extent as the signal S3a.

[0033] Comparing Fig. 8(a) and Fig. 8(b), the signals 43a and 43b related to breathing have almost the same frequency and intensity. This is because, as shown in Fig. 3, the ranges 51a and 51b correspond to the left and right chests of the living body 50, respectively, and therefore the vibrations of breathing are almost the same in the ranges 51a and 51b. The signals 44a and 44b related to vibrations other than the living body have almost the same frequency and intensity. This is because the vibrations of the vehicle transmitted to the living body 50 are almost the same, and the vibrations in the ranges 51a and 51b are detected using the radar sensor units 11a and 11b, which have almost the same configuration.

[0034] 8(c), the band limiting unit 31c removes signals other than the band 46 from the signal S1c. Therefore, the signal S3c is a signal that contains almost no signals other than the band 46. The signal S3c is mostly a signal 44c related to vibrations other than those of a living body, and contains almost no signals related to vibrations of the living body 50.

[0035] The frequency and intensity of signal 44c in Fig. 8(c) is different from the intensities of signals 44a and 44b in Fig. 8(a) and Fig. 8(b) because the intensity of the vibration transmitted to the living body 50 is not the same as the intensity of the vibration transmitted to the substrate 10.

[0036] The difference extraction unit 34a extracts the difference between the signal S3a and the signal S3b, and removes signals present in both the signal S3a and the signal S3b. For example, the signals with the highest intensity in FIG. 8(a) are the signals A1, A2, A3, A4, and A5 in order. The signals with the highest intensity in FIG. 8(b) are the signals B1, B2, B3, and B4 in order. If the frequencies of the signals A1 and B1 with the highest intensity are the same, the difference extraction unit 34a removes the signal A1 from the signal S3a. Next, if the frequencies of the signals A2 and B2 are the same, the difference extraction unit 34a removes the signal A2 from the signal S3a. Similarly, the difference extraction unit 34a removes the signal A3 from the signal S3a. The frequencies of the signals A4 and B4 do not match. Therefore, the difference extraction unit 34a does not remove the signal A4 from the signal S3a. Next, if the frequencies of the signals A5 and B4 are the same, the difference extraction unit 34a removes the signal A5 from the signal S3a. By processing in this manner, signals 43a and 44a are removed from signal S3a. Difference extraction unit 34a outputs the processed signal as signal S4a. Difference extraction unit 34a may remove from signal S3a frequency spectra having frequencies that match frequencies whose intensities are equal to or greater than a predetermined value in the frequency spectrum of signal S3b. Furthermore, difference extraction unit 34a may remove frequency spectra whose intensities are equal to or less than a predetermined value from at least one of signal S3a and signal S3b before extracting the difference.

[0037] The difference extractor 34a may use the signal S3c in addition to the signal S3a to remove the signal 44a, thereby making it possible to more appropriately remove the signal 44a.

[0038] The heartbeat extraction unit 35 synthesizes a time-axis waveform from the signal S4a to generate a waveform of the heartbeat vibration during the period T1. The heartbeat extraction unit 35 outputs the generated waveform as a signal S6a.

[0039] The heartbeat detection display unit 33 causes the output device 26 to output whether the heartbeat extraction unit 35 was able to synthesize a waveform of the heartbeat vibration. For example, if the output device 26 is a display, the heartbeat detection display unit 33 causes the output device 26 to display the heartbeat, etc. If the output device 26 is a light or a speaker, the heartbeat detection display unit 33 outputs a blinking light or a sound synchronized with the heartbeat. If the heartbeat extraction unit 35 cannot synthesize a waveform of the heartbeat vibration, the range 51a may be out of position with the heart 52. If the output device 26 indicates that the heartbeat could not be detected, the user can adjust the mounting position of the board 10, for example, by changing the mounting position of the board 10, so that the heartbeat can be detected.

[0040] The difference extraction unit 34b extracts the difference between the signal S3b and the signal S3c, and removes the signal that exists in both the signal S3b and the signal S3c. This makes it possible to remove the signal 44b in FIG. 8(b). If the signal S3b contains the signal 42b, the difference extraction unit 34b may receive the signal S4a from the heart rate extraction unit 35 and use the signal S4a to remove the signal 42b from the signal S3b. The difference extraction unit 34b outputs the processed signal as the signal S4b.

[0041] When the signal S4b contains the signal 42b, the band limiting unit 37 limits the band so as to remove the signal 42b. For example, in FIG. 8(b), the signal 42b can be removed by removing signals having a frequency of 1 Hz or more. The band limiting unit 37 outputs the processed signal as a signal S5b. The band limiting unit 37 need not be provided.

[0042] The respiration extraction unit 38 synthesizes a time-axis waveform from the signal S5b to generate a waveform of the respiration vibration for the period T1. The respiration extraction unit 38 outputs the generated waveform as a signal S6b. The biological signal analysis unit 36 ​​analyzes the signals S6a and S6b. The output unit 39 outputs the analysis result.

[0043] The biosignal analysis unit 36 ​​outputs a signal S7 that synchronizes the periods during which the Fourier transform units 32a, 32b, 32c, the difference extraction units 34a, 34b, the heartbeat extraction unit 35, the band limiting unit 37, the respiration extraction unit 38, and the output unit 39 operate. The Fourier transform units 32a, 32b, and 32c perform Fourier transform based on the synchronization signal. Therefore, the periods during which the signals S1a, S1b, and S1c are Fourier transformed are substantially the same. The period of Fourier transform is, for example, the period T1 in FIG. 4(a) to FIG. 5(b).

[0044] FIG. 9 is another example of a functional block diagram of the processing performed by the processing unit 30 in the first embodiment. As shown in FIG. 9, in this example, the sensor 21 is not provided, and the signal S1c is not input to the processing unit 30. The difference extraction unit 34c performs a difference process between the signal S2a output from the band limiting unit 31a and the signal S2b output from the band limiting unit 31b. The difference extraction unit 34c subtracts S2b from the signal S2a, for example, thereby subtracting the waveform of FIG. 4(b) from the waveform of FIG. 4(a). Therefore, the signal S2d output from the difference extraction unit 34c is a signal mainly related to the vibration of the heartbeat. The Fourier transform unit 32 performs a Fourier transform on the signal S2d and outputs a signal S3d. The processing of the heartbeat extraction unit 35, the biosignal analysis unit 36, and the output unit 39 is the same as that of FIG. 7, and the description will be omitted.

[0045] 9, the difference extraction unit 34c may extract the difference between the signal S2a and the signal S2b before the Fourier transform, and the Fourier transform unit 32 may perform a Fourier transform on the signal S2d obtained by extracting the difference. This allows the signals 43a and 44a to be appropriately removed.

[0046] 10(a) to 11(b) are diagrams showing an example of mounting the detection device 100 to a vehicle. As shown in FIG. 10(a), a seat 60 and a handlebar 62 are provided in the vehicle. The detection system includes the detection device 100 and a mounting member 64. The detection device 100 is mounted to the seat 60 by the mounting member 64. The detection device 100 irradiates signals 56a and 56b to a living body 50 in a space. The signal 56a is irradiated to a part of the living body 50 near the heart 52 on the back, and the signal 56b is irradiated to the back of the living body 50 away from the heart 52.

[0047] 10(b), the detection device 100 is attached to a seat belt 65 by an attachment member 64. The detection device 100 may be attached to a card holder worn around a person's neck. The signal 56a is irradiated to the chest of the living body 50 near the heart 52, and the signal 56b is irradiated to the chest of the living body 50 away from the heart 52.

[0048] 11(a), the detection device 100 is mounted to a dashboard or console near a steering wheel 62 by a mounting member 64. A signal 56a is directed to the chest of the living body 50 near the heart 52, and a signal 56b is directed to the chest of the living body 50 away from the heart 52.

[0049] 11(b), the detection device 100 is attached to a ceiling 66 or a sun visor by a mounting member 64. The signal 56a is irradiated to the chest of the living body 50 near the heart 52, and the signal 56b is irradiated to the chest of the living body 50 away from the heart 52.

[0050] 10(a) and 10(b), the detection device 100 can be attached close to the living body 50, so that reflection of the signals 56a and 56b by metals, etc. can be suppressed. In addition, since the passenger sits in approximately the same position on the seat, it is not necessary to adjust the irradiation direction of the signals 56a and 56b.

[0051] According to the first embodiment, as shown in FIG. 1 and FIG. 3, the radar sensor unit 11a (first sensor) transmits a signal 56a (first electromagnetic wave) to a range 51a (first range) of the living body 50 and receives a signal 58a reflected in the range 51a. The radar sensor unit 11b (second sensor) transmits a signal 56b (second electromagnetic wave) to a range 51b (second range different from the first range) of the living body 50 and receives a signal 58b reflected in the range 51b. The processing unit 30 (calculation unit) calculates information about the living body 50 (e.g., information about the heartbeat) based on the signal S1a (first signal) output by the radar sensor unit 11a and the signal S1b (second signal) output by the radar sensor unit 11b. In this way, by using the signals of the radar sensor units 11a and 11b, it is possible to remove noise caused by vibrations of a vehicle or the like and calculate information about the living body 50.

[0052] By making the range 51a closer to the heart 52 than the range 51b, the signal 40 related to the vibration of the heartbeat included in the signal S1b becomes smaller than the signal S1a, as shown in Figs. 4(a) to 5(b). Therefore, by using the signals S1a and S1b, the processing unit 30 can calculate information related to the heartbeat of the living body 50. By making the range 51a the left chest and the range 51b the right chest, the vibrations other than the vibration of the heartbeat become almost the same in the ranges 51a and 51b. Therefore, the processing unit 30 can calculate information related to the heartbeat of the living body 50 with high accuracy. The range 51b may be the neck or the abdomen. In addition, by making the range 51a a part with an artery and making the range 51b a part without an artery, the processing unit 30 can calculate information related to the pulse of the living body. It is preferable that the ranges 51a and 51b are close to each other in terms of making the vibrations other than the heartbeat or the pulse in the ranges 51a and 51b almost the same. It is considered that vibrations such as heartbeat, pulse, and breathing are different in different ranges of the living body 50. Therefore, if the ranges 51a and 51b are different ranges of the living body 50, the processing unit 30 can calculate information regarding, for example, the heartbeat, pulse, or breathing of the living body 50. Note that, although the first embodiment has been described with the example of the living body 50 being a human, the living body 50 may be a living body such as a pet.

[0053] As shown in Fig. 7, the processing unit 30 calculates information about the living body 50 based on a signal S3a (third signal) obtained by Fourier transforming the signal S1a and a signal S3b (fourth signal) obtained by Fourier transforming the signal S1b. As shown in Figs. 8(a) and 8(b), the processing unit 30 compares, for example, the frequency of the frequency spectrum of the signal S3a with the frequency of the frequency spectrum of the signal S3b, and calculates information about the living body 50 based on the comparison result. More specifically, when the frequency of the frequency spectrum of the signal S3b and the frequency of the frequency spectrum of the signal S3a are approximately the same, the frequency spectrum with the approximately same frequency is removed from the signal S3a. This makes it possible to remove signals having a common frequency in the signals S3a and S3b.

[0054] 9, the processing unit 30 may calculate information about the living body 50 based on the signals S2a and S2b before Fourier transform. The processing unit 30 may calculate a signal about the living body 50 based on, for example, the difference between the signals S2a and S2b.

[0055] The first period during which the Fourier transform unit 32a performs the Fourier transform on the signal S2a and the second period during which the Fourier transform unit 32b performs the Fourier transform on the signal S2b are substantially the same period. That is, the start time of the period T1 in FIG. 4(a) and the period T1 in FIG. 4(b) are substantially the same in real time, and the end time of the period T1 is substantially the same in real time. This can improve the calculation accuracy of the information on the living body 50. Note that the first period and the second period being substantially the same means that they are the same to the extent that no error occurs in the processing of the processing unit 30.

[0056] The antennas 12a (first transmitting antenna), 13a (first receiving antenna), 12b (second transmitting antenna) and 13b (second receiving antenna) are mounted on a substrate 10 (base). The sensor 21 (third sensor) detects vibrations of the substrate 10. The processing unit 30 calculates information about the living body 50 based on a signal S1c (fifth signal) output by the sensor 21. This improves the accuracy of calculating information about the living body 50. The processing using the sensor 21 is auxiliary processing, and the processing using the sensor 21 does not need to be performed. That is, in FIG. 1 and FIG. 7, the vibration sensor unit 11c, the band limiting unit 31c and the Fourier transform unit 32c do not need to be provided.

[0057] 7, the processing unit 30 calculates information about respiratory vibration, but the information about respiratory vibration does not have to be calculated. That is, the difference extraction unit 34b, the band limiting unit 37, and the respiratory extraction unit 38 do not have to be provided.

[0058] The heartbeat detection display unit 33 outputs whether or not the information on the living body has been calculated. This allows the user to know whether or not the ranges 51a and 51b are appropriate. If the ranges 51a and 51b are not appropriate, the ranges 51a and 51b can be adjusted. The heartbeat detection display unit 33 does not have to be provided.

[0059] In the first embodiment, the Doppler method is used to detect information about the living body 50. Other methods such as the FM-CW (Frequency Modulated Continuous Wave) method may be used to detect information about the living body 50. Furthermore, the object onto which the signals 56a and 56b are irradiated may be something other than a living body, and the processing unit 30 may calculate information about the object that reflects the signals 56a and 56b.

[0060] As shown in Fig. 10(a) to Fig. 11(b), the attachment member 64 attaches the detection device 100 so that the range 51a is closer to the heart 52 than the range 51b. This allows the processing unit 30 to calculate information about the heartbeat with high accuracy. The attachment member 64 attaches the detection device to the vehicle. This allows the processing unit 30 to calculate information about the living body 50 with high accuracy even if the vehicle vibrates. Fig. 10(a) to Fig. 11(b) are described using a vehicle such as an automobile as an example of the vehicle, but the vehicle may be a train or an airplane. The passenger of the vehicle may be the driver or a passenger. From the viewpoint of safe operation of the vehicle, the driver's biological information may be managed. For example, the driver's health condition, such as mental state, drowsiness, arrhythmia, or cardiac arrest, may be managed, and if the driver is in a serious condition, a warning, notification, or automatic stop of operation may be performed, thereby preventing serious accidents. In such a case, it is preferable to calculate information about the driver's biological information.

[0061] The present invention is not limited to the above-described embodiment, but can be modified in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0062] 10 substrate, 12a, 12b, 13a, 13b antenna, 16a, 16b high frequency circuit, 20a, 20b filter, 30 processing section, 50 living body, 51a, 51b range, 52 heart, 40, 41, 42a, 42b, 43a, 43b, 44a, 44b, 44c, 56a, 56b, 58a, 58b signal, mounting member 64

Claims

1. a first sensor having a first transmitting antenna that transmits a first electromagnetic wave to a first range of an object and a first receiving antenna that receives the first electromagnetic wave reflected in the first range, and that outputs a first signal based on the received first electromagnetic wave; a second sensor including a second transmitting antenna that transmits second electromagnetic waves to a second range on the object that is different from the first range, and a second receiving antenna that receives the second electromagnetic waves reflected in the second range, and that outputs a second signal based on the received second electromagnetic waves; a substrate having a front surface and a back surface, the first sensor and the second sensor being mounted on the front surface; an accelerometer that detects vibrations of the substrate and outputs a third signal based on the detected vibrations; a processing unit that extracts a first difference based on the first signal output by the first sensor and the second signal output by the second sensor, and extracts a second difference based on the second signal output by the second sensor and the third signal output by the accelerometer, and outputs the first difference and the second difference as information related to the object that has reflected the first electromagnetic wave and the second electromagnetic wave; Equipped with The processing unit generates heart rate information of the living body based on the extracted first difference when the object is a living body, and generates respiratory information of the living body based on the extracted second difference.

2. The detection device according to claim 1 , wherein the processing unit extracts the first difference based on a fourth signal obtained by Fourier transforming the first signal and a fifth signal obtained by Fourier transforming the second signal.

3. The detection device according to claim 2 , wherein the processing unit compares the frequency spectrum of the fourth signal with the frequency spectrum of the fifth signal, and extracts the first difference based on a comparison result.

4. A detection system including a detection device installed in a vehicle and calculating information on a living body present in the vehicle, The detection device includes: a first sensor including a first transmitting antenna that transmits a first electromagnetic wave to a first range of the living body and a first receiving antenna that receives the first electromagnetic wave reflected from the first range, and that outputs a first signal based on the received first electromagnetic wave; a second sensor including a second transmitting antenna that transmits second electromagnetic waves to a second range in the living body that is different from the first range, and a second receiving antenna that receives the second electromagnetic waves reflected in the second range, and that outputs a second signal based on the received second electromagnetic waves; a substrate having a front surface and a back surface, the first sensor and the second sensor being mounted on the front surface; an accelerometer that detects vibrations of the substrate and outputs a third signal based on the detected vibrations; a processing unit that extracts a first difference based on the first signal output by the first sensor and the second signal output by the second sensor, and extracts a second difference based on the second signal output by the second sensor and the third signal output by the accelerometer; Equipped with the detection device is installed so that the first range is closer to the heart of the living body than the second range, and the processing unit generates heart rate information of the living body from the extracted first difference, and generates respiratory information of the living body from the extracted second difference.

5. A first sensor having a first transmitting antenna that transmits a first electromagnetic wave to a first range of an object and a first receiving antenna that receives the first electromagnetic wave reflected in the first range, and that outputs a first signal based on the received first electromagnetic wave; a second sensor including a second transmitting antenna that transmits second electromagnetic waves to a second range on the object that is different from the first range, and a second receiving antenna that receives the second electromagnetic waves reflected in the second range, and that outputs a second signal based on the received second electromagnetic waves; a processing unit that extracts a difference between the first signal output by the first sensor and the second signal output by the second sensor, and outputs the difference as information related to the object that reflected the first electromagnetic wave and the second electromagnetic wave; Equipped with The processing unit is a detection device that, when the object is a living body, generates heart rate information of the living body based on the extracted difference.

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