WO2017094347A1

WO2017094347A1 - Pulse and respiration detecting device

Info

Publication number: WO2017094347A1
Application number: PCT/JP2016/079551
Authority: WO
Inventors: ▲貞▼旬金; 幸夫大瀧
Original assignee: アルプス電気株式会社
Priority date: 2015-12-02
Filing date: 2016-10-04
Publication date: 2017-06-08

Abstract

Provided is a pulse and respiration detecting device that can accurately detect the pulse rate and respiratory rate of a subject. A pulse and respiration detecting device (10) disposed on a seat in a vehicle comprises: a base plate (20); an antenna (28) that is disposed on one face of the base plate (20); a transceiver (25, 26) that, via the antenna (28), transmits a transmission wave to a subject seated in a seat and receives a reflected wave of the transmission wave; a detecting unit (31) to detect the phase difference between the transmission wave and the reflected wave; and a calculation processing device (34) that calculates the pulse rate and the respiratory rate of the subject on the basis of the phase difference detected by the detecting unit (31). A metal reflection plate (53) comprising at least a face that is opposite the antenna (28) is disposed in a position where the distance to the antenna (28) is no more than 1/4 of the wavelength of the transmission wave, and the face opposite the antenna (28) faces the subject.

Description

Pulse respiration detector

The present invention relates to a pulse respiration detection device that detects a pulse rate and a respiration rate of a subject who is seated in a vehicle seat.

Patent Document 1 supplies first and second antennas, first and second mixer circuits to which first and second received signals received by these antennas are input, and these mixer circuits, respectively. A signal generation circuit that generates a pulse signal, a signal that the first mixer circuit mixes and outputs the first reception signal and the pulse signal, and a second mixer circuit that outputs the second reception signal and the pulse signal When the pulse signal is fed to the first and second antennas to radiate radio waves, the previous pulse signal is supplied to the first antenna. After being fed to the first mixer circuit at the same time as the power is supplied, the next pulse signal is supplied at a close timing that does not overlap with the pulse width of the previous pulse signal applied to the first antenna and the first mixer circuit. Powered by the antenna At the same time, a wireless sensor device comprising: control means for controlling the operation timing of the signal generation circuit and the path from the signal generation circuit to the first and second antennas so as to be supplied to the second mixer circuit Disclosure.

According to this wireless sensor device, it is possible to detect the azimuth and movement of the object from the reflected wave of the radiated radio wave object, and between the antennas without interfering with each other's radio waves. Therefore, the device can be miniaturized and the peak power required for the oscillator can be halved.

JP 2011-94997 A

Using the wireless sensor device described in Patent Document 1, when trying to acquire biological information of a subject seated in a vehicle seat, the position and environment where the device is installed, and the biological information to be acquired Depending on the type, the antenna reception sensitivity may not be sufficient. In particular, the reflected wave corresponding to changes in the pulse rate and respiratory rate is weaker in signal strength than the reflected wave corresponding to the movement of the entire subject's body, so it may be necessary for detection depending on conditions such as the installation position of the device. There is a case where a signal with a strong intensity cannot be obtained.

In addition, when the subject person is a driver and the wireless sensor device is installed on the seat of the driver's seat, the radio wave radiated from the wireless sensor device is directed backward, so the movement of the person sitting on the rear seat (body Motion) may also be detected. Here, there are cases where the movement of the person sitting in the back seat is greater than that of the driver. In such a case, the driver's pulse rate and respiratory rate may not be measured accurately.

Therefore, an object of the present invention is to provide a pulse respiration detection device and a pulse respiration sensor that can accurately detect the pulse rate and respiration rate of a subject who is seated in a specific seat.

In order to solve the above problems, a pulse respiration detection device according to the present invention is a pulse respiration detection device arranged in a seat in a vehicle, and includes a substrate, an antenna arranged on one side of the substrate, and the antenna. A transmitter / receiver that transmits a transmission wave to the subject seated in the seat and receives the reflected wave, a detection unit that detects a phase difference between the transmission wave and the reflected wave, and a detection unit An arithmetic processing unit that calculates the pulse rate and respiration rate of the subject based on the phase difference, and has at least a surface facing the antenna at a position where the distance to the antenna is 1/4 or less of the wavelength of the transmission wave A metal reflector is disposed, and the surface facing the antenna is disposed to face the subject.

As a result, the directivity of the antenna with respect to the outside of the metal reflector can be suppressed, and the directivity with respect to the subject can be increased, so that the detection sensitivity can be increased and the influence of the person sitting in the seat behind the subject Can be suppressed.

In other words, since transmission of the transmission wave to the outside of the metal reflector and reception of the reflected wave reflected from the rear seat are suppressed, it is possible to detect the pulse respiration of the subject by the movement of the person sitting in the seat behind the subject. The influence of can be suppressed.

In addition, because the position of the antenna and the metal reflector is separated by a predetermined amount, the phase of the transmitted wave radiated to the subject and the transmitted wave reflected by the metal reflector and radiated to the subject substantially matches, Detection sensitivity can be increased.

In the pulse respiration detection device of the present invention, the metal reflector is fixed to the mounting plate via an insulating spacer, and the mounting plate is provided with a support member extending from the base to the substrate, and the support member And the substrate are preferably engaged with each other.

Thereby, the antenna and the metal reflector can be made non-conductive, and the distance between them can be defined. The transmitted wave radiated to the subject and the transmitted wave reflected by the metal reflector and radiated to the subject Can be made to substantially coincide with each other.

In the pulse respiration detection device of the present invention, it is preferable that a shield member having an effect of attenuating electromagnetic waves by a predetermined value or more is disposed outside the metal reflector.

Here, the outside of the metal reflector is a direction away from the metal reflector in a direction in which the metal reflector and the antenna face each other.

As a result, transmission of electromagnetic waves to the seat behind the subject and reception of reflected waves from the seat behind can be suppressed, so that detection sensitivity can be further increased and a person sitting on the seat behind the subject The influence of can be suppressed.

In the pulse respiration detection device of the present invention, it is preferable that the shield member is a mesh material including a metal thread, and is disposed so as to cover the metal reflector and the antenna with the subject side opened.

As a result, transmission of transmitted waves and reception of reflected waves can be reliably performed on the subject side, and transmission of transmitted waves and reception of reflected waves can be more effectively suppressed for seats behind the subject. it can.

The pulse respiration detection device of the present invention is preferably disposed inside the backrest of the seat.
The space in the vehicle can be arranged efficiently without narrowing the space.

According to the present invention, the antenna directivity is controlled by a configuration in which a metal reflector having at least a surface facing the antenna is disposed at a position where the distance to the antenna is ¼ or less of the wavelength of the electromagnetic wave. It is possible to provide a pulse respiration detection device capable of accurately detecting a pulse rate and a respiration rate of a subject who is seated in a specific seat.

It is a perspective view showing the state where the pulse respiration detection device concerning an embodiment is arranged in the seat of vehicles. It is a figure which shows the state by which the pulse respiration detection apparatus which concerns on embodiment is arrange | positioned in the seat of a vehicle, Comprising: (A) is a rear view, (B) is a side view. It is a figure which shows arrangement | positioning of the pulse respiration detection apparatus which concerns on embodiment, Comprising: (A) is a top view, (B) is a front view. It is a perspective view which shows the structure of the detection part of the pulse respiration detection apparatus which concerns on embodiment. It is a perspective view which shows the structure of the detection apparatus main body in embodiment. It is a side view which shows the structure of the detection apparatus main body in the embodiment, an insulation spacer, and a metal reflecting plate. It is a figure which shows the structure of the board | substrate in the detection apparatus main body of embodiment, Comprising: (A) is a front view, (B) is a side view. It is a block diagram which shows the circuit structure of the detection apparatus main body in embodiment. It is a table | surface which shows the received electric power which received the electromagnetic waves radiated | emitted from a detection part on the back side of a backrest, and received the electric power in the state without a shield curtain (shield member). It is a graph which shows the received electric power which received the electromagnetic waves radiated | emitted from a detection part on the back side of a backrest when the size of a metal reflecting plate was changed. It is a figure which shows the directivity characteristic and impedance characteristic of an antenna in the pulse respiration detection apparatus of an Example. It is a figure which shows the directivity characteristic and impedance characteristic of the antenna in the pulse respiration detection apparatus of a comparative example. It is a graph which shows the change of the antenna gain with respect to the space | interval of a mounting plate and a metal reflecting plate. It is a graph which shows the change of FBR with respect to the space | interval of a mounting plate and a metal reflecting plate.

Hereinafter, a pulse respiration detection device according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a state in which a pulse respiration detection device 100 according to the present embodiment is arranged in a vehicle seat (driver's seat 1). FIG. 2 is a view showing a state in which the pulse respiration detection device 100 according to the present embodiment is arranged in a vehicle seat (driver's seat 1), where (A) is a rear view and (B) is a side view. is there. As shown in FIG. 1, the pulse respiration detection device 100 according to this embodiment includes a detection unit 60 and a shield curtain 50. In this embodiment, although the form provided with the shield curtain 50 is shown, the form which consists only of the detection apparatus main body 10 without providing the shield curtain 50 is also possible. Moreover, although the form provided in the driver's seat 1 is shown in the present embodiment, the present invention can be applied to a passenger seat and a rear seat of the vehicle.

The detecting unit 60 is disposed inside the backrest (back seat) 3 of the driver's seat 1 in the vehicle. From the detection unit 60, an electromagnetic wave Wa as an inspection signal wave is irradiated from the front surface 3 b side of the backrest 3 to the subject 5 (driver) sitting on the seat surface 2 of the driver seat 1. The electromagnetic wave Wa is reflected by the subject 5, and the reflected wave Wb is received by the detection unit 60. In the detection unit 60, the pulse rate and the respiratory rate of the subject 5 are calculated based on the phase difference between the electromagnetic wave Wa and the reflected wave Wb.

The shield curtain 50 (shield member) has, for example, a configuration in which a metal thread is knitted into a cloth to form a mesh, and has an effect of attenuating electromagnetic waves by a predetermined value or more. As shown in FIGS. 1 and 2, the shield curtain 50 is arranged on the back surface 3 a of the backrest 3 so as to cover at least a range corresponding to the back surface of the detection unit 60. In other words, the shield curtain 50 is disposed on the back surface 3a side so as to cover the detection unit 60 in a state where the front surface 3b side of the backrest 3 is opened. By arranging the shield curtain 50 in this way, the transmission of the electromagnetic wave Wa to the rear of the driver's seat 1 and the reception of the reflected wave Wb from the rear can be suppressed, and therefore, from a person sitting in the rear seat Therefore, the pulse rate and respiratory rate of the subject 5 can be accurately detected based on the reflected wave from the subject 5 sitting in the driver's seat. Here, it is preferable to use copper as the metal used for the metal yarn of the shield curtain 50 because the attenuation can be increased.

FIG. 3 is a view showing the arrangement of the pulse respiration detection device 100 according to the present embodiment, where (A) is a top view and (B) is a front view. FIG. 4 is a perspective view illustrating a configuration of the detection unit 60 of the pulse respiration detection apparatus 100 according to the present embodiment. 3A and 4 show a state before assembling the members.

As shown in FIGS. 3A and 4, the detection unit 60 includes a metal reflection plate 53, a spacer 51, and a fixing plate 52 that are arranged in order from the back surface 3 a to the front surface 3 b of the backrest 3. On the front surface 53 b of the reflecting plate 53, that is, on the front surface 3 b side of the backrest 3, the detection device main body 10 is disposed via an insulating spacer 70.

As shown in FIG. 4, the spacer 51 has a frame shape corresponding to the outer edge shape of the metal reflector 53, and an opening 51a is formed at the center. The thickness of the spacer 51 in the Y1-Y2 direction is set so that the detection device body 10 does not protrude from the spacer 51 in the Y1 direction when the spacer 51 is disposed on the front surface 53b of the metal reflector 53. The fixed plate 52 is a plate-like member provided with an opening 52a at substantially the center, and has substantially the same outer shape as the spacer 51. The fixing plate 52, the spacer 51, and the metal reflecting plate 53 are sequentially stacked in the Y1-Y2 direction, and are fixed to each other by bonding or the like. At this time, since the opening 52a of the fixed plate 52 and the opening 51a of the spacer 51 are provided at positions corresponding to the detection device main body 10 on the metal reflection plate 53, the transmission wave transmitted from the detection device main body 10 and The reflected wave toward the detection device main body 10 passes through the

openings

51a and 52a.

FIG. 5 is a perspective view showing a configuration of the detection apparatus main body 10. FIG. 6 is a side view illustrating the configuration of the detection device main body 10, the insulating spacer 70, and the metal reflector 53.

As shown in FIGS. 5 and 6, the detection device main body 10 includes a substrate 20 and a mounting plate 40. Further, as shown in FIG. 6, on the back surface 43a of the mounting plate 40, one surface side of the insulating spacer 70 is fixed with an adhesive or the like, and the other surface side of the insulating spacer 70 on the front surface 53b of the metal reflecting plate 53 is an adhesive or the like. It is fixed with. The mounting plate 40 and the metal reflector 53 may be made of the same metal material, but for example, different materials such as white and aluminum may be used. Further, the insulating spacer 70 may be a non-conductive material or a dielectric, and for example, ABS may be used. At both ends in the Z1-Z2 direction of the main surface 43 (base portion) of the mounting plate 40, cut-and-raised portions 41 and 42 (support members) are provided so as to extend toward the substrate 20. The

tip portions

41a, 41b, 42a, 42b of the cut and raised

portions

41, 42 and the substrate 20 are engaged with each other as will be described later.

As a result, as shown in FIG. 6, the substrate 20 is supported by the mounting plate 40, the back surface 20a of the substrate 20 and the front surface 53b of the metal reflecting plate 53 face each other, and the distance is D. More specifically, the distance D is the distance between the antenna 28 provided on the substrate 20 and the metal reflector 53, and is set to ¼ or less of the wavelength of the transmission wave transmitted by the RF transmitter 25. Yes. The detection device main body 10 is arranged in the backrest 3 with the front surface 20b side of the substrate 20 facing the subject 5 side and the back surface 53a of the metal reflector 53 facing the back surface 3a side of the backrest 3.

7A and 7B are diagrams showing the configuration of the substrate 20 in the detection apparatus main body 10, wherein FIG. 7A is a front view and FIG. 7B is a side view. As shown in FIG. 7A, the substrate 20 is formed in a rectangular shape in plan view, and on the front surface 20b, a ground pattern 22 made of copper is formed in a region excluding the outer peripheral edge. Here, the overall shape of the substrate 20 is not limited to the shape shown in FIGS. 7A and 7B, and may be other shapes that match the shape of the peripheral device for incorporation into the actual device. In the following description, the lower long side of the substrate 20 is adjacent to the first side L1, the upper long side opposite to the first side L1 is adjacent to the second side L2, and the first side L1. These two short sides are referred to as third and fourth side portions L3 and L4.

In the vicinity of the first side portion L1 of the front surface 20b of the substrate 20, a slot 23 is formed in parallel along the first side portion L1 so as to leave a part of the lower outer edge portion of the ground pattern 22. Yes. The slot 23 is formed in a rectangular shape in plan view extending in a strip shape with a predetermined width, and is formed in the same length in the left-right direction (Z1-Z2 direction) from the center of the first side portion L1 of the substrate 20. A power supply line 24 serving as a power supply unit is provided at a position corresponding to the slot 23 on the back surface 20 a of the substrate 20. The power supply line 24 is branched into two line

power supply units

24a and 24b, and the two line

power supply units

24a and 24b are symmetrically located with respect to the center in the longitudinal direction (Z1-Z2 direction) of the slot 23. It is bridged in a direction (X1-X2 direction) orthogonal to the longitudinal direction of the slot 23. The power supply line 24 is connected to a circuit unit 30 provided on the back surface 20 a of the substrate 20. The slot 23, the power supply line 24, and the line

power supply units

24 a and 24 b constitute an antenna 28, and RF transmission as a transceiver that irradiates the subject 5 with a high-frequency (RF) transmission wave (electromagnetic wave) via the antenna 28. The unit 25 and the RF receiver 26 as a transmitter / receiver that receives a reflected wave from the subject 5 are connected. The RF transmitter 25 and the RF receiver 26 are provided in the circuit unit 30.

The lateral outer edge portions of the third and fourth side portions L3 and L4 of the substrate 20 have the copper foil removed along the third and fourth side portions L3 and L4, and the copper foil removal regions A1 and A2 are respectively formed. Is formed. Through

hole portions

26a and 26b into which the

tip portions

41a and 41b of the cut and raised portion 41 are inserted are formed in the copper foil removal region A1, and the

tip portions

42a and 42b of the cut and raised portion 42 are formed in the copper foil removal region A2. Through-

hole portions

27a and 27b into which are inserted are formed. The substrate 20 and the mounting plate 40 are integrated by engaging and fixing the

tip portions

41a, 41b, 42a, 42b to the through-

hole portions

26a, 26b, 27a, 27b, respectively.

FIG. 8 is a block diagram showing a circuit configuration of the detection apparatus main body 10. As illustrated in FIG. 8, the circuit unit 30 includes an RF transmission unit 25, an RF reception unit 26, a detection circuit 31, a bandpass filter 32, a lowpass filter 33, and a control unit 34.

In the RF transmission unit 25, a transmission wave Wa as a test signal wave including a transmission signal (carrier wave signal) of a predetermined frequency is generated according to the instruction signal from the control unit 34 and transmitted from the antenna 28 toward the subject 5. The The transmission signal included in the transmission wave Wa is a high-frequency radio wave in the RF band, and preferably has a high frequency of, for example, 2 GHz or more. Further, the frequency, phase, amplitude and other information of the transmission wave Wa are given to the detection circuit 31.

The transmitted wave Wa is reflected by the subject 5, and the reflected wave Wb is received by the antenna 28 and supplied to the RF receiver 26. The reflected wave Wb is a signal wave reflected and modulated by the transmission wave Wa applied to the subject 5 in accordance with changes in the pulse rate and respiratory rate generated in the subject 5.

The reception signal S1 obtained by receiving the reflected wave Wb by the RF receiving unit 26 is given to a detection circuit 31 as a detection unit. In the detection circuit 31, a detection signal S2 as a signal indicating a phase difference between the transmission wave Wa and the reflected wave Wb is obtained from the information of the transmission wave Wa and the reception signal S1.

The band-pass filter 32 extracts a signal in a frequency band of 0.7 to 3 Hz, for example, and a measurement signal S4 mainly corresponding to the pulse rate is extracted from the detection signal S2 and given to the control unit 7.

The low-pass filter 33 extracts a signal having a frequency band of less than 0.7 Hz or less than 0.7 Hz, for example, and a measurement signal S5 mainly corresponding to the respiratory rate is extracted from the detection signal S2 and given to the control unit 34. It is done.

The control unit 34 includes a CPU, a memory, an A / D conversion unit, and the like as an arithmetic processing unit. The measurement signals S4 and S5 are converted into digital values by the A / D converter and supplied to the CPU. The CPU performs arithmetic processing based on software installed in advance, and calculates the pulse rate and respiratory rate of the subject 5 based on the phase difference detected by the detection circuit 31.

Here, the RF transmitter 25, the RF receiver 26, and the detection circuit 31 provided on the substrate 20 constitute a pulse respiration sensor.

Hereinafter, the effects of the pulse respiration detection device 100 of the present embodiment will be described with reference to FIGS. In the following examples and comparative examples, the detection device main body 10 is arranged with the board 20 side facing the subject 5 side in the backrest 3 of the driver's seat 1 in the vehicle, as in the above-described embodiment. . In both the example and the comparative example, the RF transmission unit transmits a transmission wave of 2.45 GHz and a wavelength of 120 mm.

In the detection apparatus main body 10 of the embodiment, a copper plate having a size of 200 mm × 200 mm × thickness 1 mm is used as the metal reflector 53. The substrate 20 and the mounting plate 40 are fixed at a distance of 11 mm, the thickness of the insulating spacer 70 is 15 mm, and the distance D between the antenna 28 and the metal reflector 53 is 26 mm. That is, this distance D is approximately ¼ of the wavelength of the transmission wave. The detection device main body of the comparative example has a configuration in which the metal reflector 53 is removed from the above embodiment.

FIG. 9 is a table showing the received power of the electromagnetic wave radiated from the detection unit 60 received on the back surface 3a side of the backrest 3 and the power received without the shield curtain (shield member) 50. Here, the transmission power of the RF transmission unit 25 was set to 0 dBm, and measurement was performed by changing the distance (back surface reception distance) of the detection unit 60 grounded from the detection device body 10 to the back surface 3a side. The “rear surface receiving distance” is a distance (unit: mm) from the detection apparatus body 10 to the reference receiving antenna, and the received power (unit: dBm) is measured by a spectrum analyzer which is one of power measuring apparatuses. Further, “without metal reflector” is a comparative example, and “with metal reflector (200 × 200 mm)” is an example.

As can be seen from FIG. 9, the power radiated to the back surface 3a side is smaller by 12 to 20 dB than in the comparative example. When an occupant (referred to as a rear occupant) is present in the rear seat of the driver's seat 1, the rear occupant part near the detection device main body 10 becomes a knee, and it is necessary to eliminate the influence of this movement (body movement). In an experiment conducted by the inventor, it was found that when the rear passenger's knee is at a rear receiving distance of 300 mm and the received power is about −48 dBm or less, there is no influence of the body movement. As shown in FIG. 9, in the embodiment in which the shield curtain (shield member) 50 is not provided, the back surface radiated power needs to be further attenuated by 8 dB or more when the back surface receiving distance is 300 mm.

FIG. 10 shows the received power when the electromagnetic wave radiated from the detection unit 60 is received on the back surface 3a side of the backrest 3 when the size of the metal reflector 53 is changed. Similarly to FIG. (Member) It is a graph which shows the electric power received in the state without 50. In FIG. 10, “without metal reflector” is a configuration obtained by removing the metal reflector 53 from the configuration of the above-described embodiment, and corresponds to the comparative example shown in FIG. “100 × 100 mm”, “150 × 150 mm”, and “200 × 200 mm” indicate the planar shape of the metal reflector 53 to be used, and the thickness is 1 mm in common. “200 × 200 mm” corresponds to the embodiment shown in FIG. The rear receiving distance, the power measuring device, and the measurement target amount are the same as those in the example and comparative example shown in FIG.

As can be seen by comparing the received power of each embodiment of FIG. 10 at the rear receiving distance of 300 mm, among the shapes of the three metal reflectors 53, “200 × 200 mm” as an embodiment is placed behind the driver's seat 1. The transmitted wave to be transmitted can be greatly attenuated.

11 (A) and 11 (B) are diagrams showing the directivity characteristics of the antenna 28 in the detection apparatus body 10 of the embodiment, and FIG. 11 (C) is a diagram showing the impedance characteristics of the antenna 28. 11A to 11C includes the insulating spacer 70 and the metal reflector 53. 12A and 12B are diagrams illustrating the directivity characteristics of the antenna 28 in the detection device body 10 of the comparative example, and FIG. 12C is a diagram illustrating the impedance characteristics of the antenna 28. 11A and 12A are directivity characteristics in a plane orthogonal to the X1-X2 direction, and FIGS. 11B and 12B are directivity characteristics in a plane orthogonal to the Z1-Z2 direction. (C) and FIG. 12 (C) show the resonance characteristics. 11A, 11B, and 12A, 12B, the origin is the position of the origin of the X1-Y1-Z1 orthogonal coordinate system shown in FIG. The center of In FIGS. 11A and 12A, the solid line (GainPhi) indicates the directional characteristic of the main polarization, and the broken line (GainTheta) indicates the directional characteristic of the cross polarization. On the other hand, in FIGS. 11B and 12B, a solid line (GainPhi) indicates the cross-polarization directivity and a broken line (GainTheta) indicates the main polarization directivity.

As shown in FIGS. 12A and 12B, when the metal reflector 53 is not provided, the directivity characteristics in the Y1-Y2 direction perpendicular to the substrate 20 are strong, and the omnidirectional directivity characteristics are obtained. I understand that. Further, as shown in FIG. 12C, the resonance point that is the resonance frequency of the antenna is about 2.7 GHz.

On the other hand, as shown in FIGS. 11A and 11B, when the metal reflector is provided, the directivity characteristic on the back lobe B (rear seat) side in the Y1-Y2 direction perpendicular to the substrate 20 is It can be seen that the directivity characteristic is strong only on the front lobe F (driver's seat) side, and the front directivity characteristic is obtained. It can also be seen that the directivity characteristics are suppressed on the side lobe S side (the plane direction perpendicular to the Y1-Y2 direction) as compared with the comparative example. As shown in FIG. 11C, the resonance point P1, which is the resonance frequency of the antenna of the RF transmitter 25, is about 2.45 GHz.

FIG. 13 is a graph showing measured values of antenna gain (Peak Gain, unit dBi) with respect to the distance between the mounting plate 40 and the metal reflector 53. FIG. 14 is a graph showing measured values of FBR (front-rear ratio, unit dB) with respect to the distance between the mounting plate 40 and the metal reflecting plate 53. Here, the distance between the mounting plate 40 and the metal reflecting plate 53 corresponds to the thickness of the insulating spacer 70. FBR is a value obtained by dividing the antenna gain on the front (driver's seat) side by the antenna gain on the rear (rear seat) side.

As shown in FIG. 13, the antenna gain increases with an increase in the distance between the mounting plate 40 and the metal reflector 53, and is a substantially constant value in the range where the distance is 10 mm or more. Further, as shown in FIG. 14, the FBR also increases with an increase in the distance between the mounting plate 40 and the metal reflecting plate 53, and is a substantially constant value in the range where the distance is 10 mm or more. Here, since the wavelength of the transmitted transmission wave is 120 mm as described above, when the interval at which the FBR is maximum is 15 mm, and the interval of 11 mm between the substrate 20 and the mounting plate 40 is added, the antenna 28 and the metal reflector 53 The distance D is 26 mm. That is, when the distance D is approximately ¼ of the wavelength of the transmission wave, the antenna gain on the front lobe F (driver's seat) side is maximized, and FBR is also maximized. The transmission wave is radiated to the maximum, and the radiation of the transmission wave is minimized on the back surface 3a.

9 to 14 described above based on the detection unit 60 in the absence of the shield curtain (shield member) 50, the pulse respiration detection apparatus 100 including the shield curtain (shield member) 50 has a back surface receiving distance. The received power at 300 mm was -50 dBm. In other words, when the rear occupant's knee is at a rear receiving distance of 300 mm, the received power is about −48 dBm or less, so that the body movement is not affected. Here, the shield curtain (shield member) 50 of the example has a substantially trapezoidal shape, and a conductive cloth having an upper side of 400 mm, a lower side of 500 mm, and a height of 500 mm was used.

With the configuration described above, the following effects are achieved according to the above embodiment.
(1) Since the metal reflector having at least a surface facing the antenna is disposed at a position where the distance to the antenna is ¼ or less of the wavelength of the transmission wave, the directivity characteristics of the antenna can be controlled. The detection sensitivity can be increased and the influence of the person sitting on the seat behind the subject can be suppressed.
(2) By arranging a shield curtain between the antenna and the metal reflector or outside the metal reflector, it is possible to suppress transmission of transmission waves to the seat behind the subject and reception of reflected waves from the seat behind. Therefore, the detection sensitivity can be further increased, and the influence of the person sitting on the seat behind the subject can be suppressed.

Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

As described above, the pulse respiration detection device according to the present invention is useful when it is desired to accurately detect the pulse rate and respiration rate of a subject seated in a specific seat.

DESCRIPTION OF SYMBOLS 1 Driver's seat 3 Backrest 3a Back surface 3b Front surface 5 Target person 10 Detection apparatus main body 20 Board | substrate 23 Slot (antenna)
24 Feed line (antenna)
24a Line feeder (antenna)
24b Line feeder (antenna)
25 RF transmitter (transceiver)
26 RF receiver (transceiver)
28 Antenna 30 Circuit part 31 Detection circuit (Detection part)
34 Control unit (arithmetic processing unit)
40

Mounting plate

41, 42 Cut and raised part (support member)
43 Main surface (base)
50 Shield curtain (shield member)
51 Spacer 52 Fixing Plate 53 Metal Reflecting Plate 60 Detection Unit 70 Insulating Spacer 100 Pulse Respiration Detection Device

Claims

A pulse respiration detection device disposed on a seat in a vehicle,
A substrate,
An antenna disposed on one side of the substrate;
A transceiver for transmitting a transmission wave to the subject seated in the seat and receiving the reflected wave via the antenna;
A detector for detecting a phase difference between the transmitted wave and the reflected wave;
An arithmetic processing device that calculates the pulse rate and respiratory rate of the subject based on the phase difference detected by the detection unit;
Provided,
A metal reflector having at least a surface facing the antenna is disposed at a position where the distance to the antenna is 1/4 or less of the wavelength of the transmission wave,
A pulse respiration detection device, wherein a surface facing the antenna is arranged to face the subject.
The metal reflector is fixed to the mounting plate via an insulating spacer,
2. The support plate according to claim 1, wherein a support member extending from the base portion toward the substrate is provided on the mounting plate, and the support member and the substrate are engaged with each other. Pulse respiration detector.
3. The pulse respiration detecting device according to claim 1, wherein a shield member having an effect of attenuating electromagnetic waves by a predetermined value or more is disposed outside the metal reflector.
2. The shield member according to claim 1, wherein the shield member is a mesh material including a metal thread, and is disposed so as to cover the metal reflector and the antenna with the subject side opened. Item 4. The pulse respiration detection device according to any one of Item 3.
The pulse respiration detection device according to any one of claims 1 to 4, wherein the pulse respiration detection device is disposed inside a backrest of the seat.