WO2021014884A1

WO2021014884A1 - Occupant sensing device and seat

Info

Publication number: WO2021014884A1
Application number: PCT/JP2020/025217
Authority: WO
Inventors: 敦彦大井川
Original assignee: ＪｏｙｓｏｎＳａｆｅｔｙＳｙｓｔｅｍｓＪａｐａｎ株式会社
Priority date: 2019-07-25
Filing date: 2020-06-26
Publication date: 2021-01-28
Also published as: JP7272890B2; JP2021020510A

Abstract

Provided is an occupant sensing device comprising: a vibration unit which is installed in a metal support member supporting a seat cushion from below; a first piezoelectric element which is installed in the seat cushion; a second piezoelectric element which is installed in the support member; a drive circuit which outputs a drive signal for causing the vibration unit to vibrate such that vibrations are propagated to the support member; and a sensing circuit which carries out living body sensing by detecting a first vibration waveform of a lower frequency than the drive signal via a sensing line connected to the first piezoelectric element, and which carries out load sensing by detecting an amplitude change in a second vibration waveform obtained via a sensing line connected to the second piezoelectric element.

Description

Crew detection device and seat

The present invention relates to an occupant detection device and a seat.

Conventionally, a biometric information detection device is known which includes a sensor composed of a piezoelectric element arranged at a place where it comes into direct or indirect contact with the human body, and detects biometric information of the human body and estimates the mass from the output of this sensor. (See, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2001-204694

However, since the conventional technology uses the value of the sensor output waveform during the attenuation period for mass estimation, it is difficult to accurately estimate the mass when the sensor output waveform is greatly attenuated.

Therefore, the present disclosure provides an occupant detection device and a seat capable of detecting an occupant with high accuracy.

This disclosure is
A vibrating part installed on a metal support member that supports the seat cushion from below,
The first piezoelectric element installed on the seat cushion and
A second piezoelectric element installed on the support member and
A drive circuit that outputs a drive signal that vibrates the vibrating portion so that the vibration propagates to the support member.
Biometric detection is performed by detecting a first vibration waveform whose frequency is lower than that of the drive signal via a detection line connected to the first piezoelectric element, and a detection line connected to the second piezoelectric element. Provided is an occupant detection device including a detection circuit that detects a load by detecting an amplitude change of a second vibration waveform obtained via the above.

In addition, this disclosure is
With a seat cushion
A metal support member that supports the seat cushion from below, and
The vibrating part installed on the support member and
The first piezoelectric element installed on the seat cushion and
A second piezoelectric element installed on the support member and
A drive circuit that outputs a drive signal that vibrates the vibrating portion so that the vibration propagates to the support member.
Biometric detection is performed by detecting a first vibration waveform whose frequency is lower than that of the drive signal via a detection line connected to the first piezoelectric element, and a detection line connected to the second piezoelectric element. Provided is a sheet including a detection circuit that detects a load by detecting an amplitude change of a second vibration waveform obtained via the above.

According to the technology of the present disclosure, it is possible to provide an occupant detection device and a seat capable of detecting an occupant with high accuracy.

It is a block diagram which shows the configuration example of an occupant detection system. It is a figure which shows typically the configuration example of the occupant detection system. It is an exploded perspective view which shows the structural example of a seat cushion and a support member. It is a figure which illustrates the 1st vibration waveform and the 2nd vibration waveform. It is a figure which illustrates the amplitude change of the 2nd vibration waveform by a load. It is a figure which shows the example of attaching the 1st piezoelectric element to a seat cushion. It is a figure which shows the example of attachment to the S spring of the load sensor for load detection. It is a figure which shows the structural example of the load sensor. It is a figure which shows the 1st specific mounting example of the 1st piezoelectric element. It is a figure which shows the 2nd specific mounting example of the 1st piezoelectric element. It is a figure which shows the 3rd specific mounting example of the 1st piezoelectric element. It is sectional drawing which shows the 1st specific mounting example of the vibrating part and the 2nd piezoelectric element. It is sectional drawing which shows the 2nd specific mounting example of the vibrating part and the 2nd piezoelectric element. It is a figure which shows the 1st wiring example which acquires the 1st vibration waveform and the 2nd vibration waveform through a common detection line. It is a figure which shows the detail of the 1st wiring example. It is a figure which shows the 1st wiring example in detail. It is a figure which shows the 2nd wiring example which acquires the 1st vibration waveform and the 2nd vibration waveform through separate detection lines. It is a figure which shows the structural example of a piezoelectric line.

Hereinafter, the occupant detection system according to the embodiment according to the present disclosure will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of the occupant detection system according to the embodiment of the present disclosure. The occupant detection system shown in FIG. 1 detects an occupant sitting on the seat 40 mounted on the vehicle and outputs the detection result to an external device. This occupant detection system includes a seat 40 installed in the vehicle interior and an occupant detection device 100 that detects an occupant sitting on the seat 40.

FIG. 2 is a diagram schematically showing a configuration example of the occupant detection system according to the embodiment of the present disclosure. The seat 40 has a seat cushion 44, a seat back 45, and a support member 41.

The seat cushion 44 is a seat portion that supports the buttocks and thighs of the occupant sitting on the seat 40 from below. The seating surface of the seat cushion 44 comes into contact with the buttocks and thighs of the occupant sitting on the seat 40. The seat cushion 44 has a cushion pad 43 and a seat trim 42. The cushion pad 43 is a cushioning member that is supported from below by the support member 41. The cushion pad 43 is formed of, for example, urethane foam. The seat trim 42 is a base material that covers the cushion pad 43 and forms a seating surface of the seat cushion 44. The seat trim 42 is, for example, a skin member formed of fabric or leather.

The seat back 45 is a backrest portion that rises from the rear portion of the seat cushion 44 and supports the back of the occupant sitting on the seat 40 from the rear. The backrest surface of the seat back 45 comes into contact with the back of the occupant sitting on the seat 40.

The support member 41 is a metal member that supports the seat cushion 44 from below. The support member 41 has a cushion support portion such as an S spring that contacts the lower surface of the seat cushion 44.

FIG. 3 is an exploded perspective view showing a configuration example of the seat cushion and the support member. The seat cushion 44 has a cushion pad 43 having cushioning properties, and a seat trim 42 installed on the upper surface of the cushion pad 43. In the form shown in FIG. 3, the support member 41 has a pair of

side frames

41a and 41b, a front frame 41c, a rear frame 41d, and a plurality of S springs 41e.

The pair of

side frames

41a and 41b are arranged apart from each other in the left-right direction corresponding to the vehicle width direction. The front frame 41c connects the front portions of the pair of

side frames

41a and 41b, and the rear frame 41d connects the rear portions of the pair of

side frames

41a and 41b. The S spring 41e is an example of a cushion support portion that supports the seat cushion 44 from below, and comes into contact with the lower surface of the cushion pad 43. The S spring 41e is a metal elastic wire having S-shaped portions that are repeatedly continuous.

FIG. 3 illustrates a form in which a plurality of S springs 41e arranged in the left-right direction are erected between the front frame 41c and the rear frame 41d, but the plurality of S springs 41e arranged in the front-rear direction are illustrated. May be erected between a pair of

side frames

41a, 41b.

In FIG. 1, the occupant detection device 100 includes a vibration unit 10, a first piezoelectric element 121, a second piezoelectric element 122, and a control device 30. The control device 30 is an ECU (Electronic Control Unit) having a drive circuit 31 and a detection circuit 37.

The vibrating portion 10 is installed on a metal support member 41 that supports the seat cushion 44 from below, and is installed on a cushion support portion such as the S spring 41e described above, for example. The vibrating unit 10 is connected to the drive circuit 31 via the drive line 11.

The vibrating unit 10 vibrates according to the drive signal D supplied from the drive circuit 31 via the drive line 11. The vibration generated in the vibrating unit 10 propagates to the metal support member 41.

The vibrating unit 10 is, for example, a piezoelectric element that vibrates when a drive signal D from the drive circuit 31 is supplied. The vibrating portion 10 may be any of a bimorph type, a laminated type or a monomorph type piezoelectric element. Further, the vibrating portion 10 may use a piezoelectric polymer.

The drive circuit 31 supplies a drive signal D that vibrates the vibrating unit 10 to the vibrating unit 10 via the drive line 11 so that the vibration propagates to the support member 41. The drive circuit 31 sends a drive signal D that vibrates the vibrating unit 10 so that the vibrating unit 10 vibrates with a size that does not cause the occupant on the seat cushion 44 to feel the vibration during the period of biological detection and load detection. Output. The waveform of the drive signal D (drive waveform) has a constant amplitude and a constant frequency (for example, 5 kHz). The drive waveform may be a square wave or a sine wave.

The first piezoelectric element 121 is a piezoelectric element for biological detection installed on the seat cushion 44. The second piezoelectric element 122 is a load detecting piezoelectric element installed on the support member 41.

The detection circuit 37 performs biological detection by detecting the first vibration waveform Sa whose frequency is lower than the drive signal D via the detection line 13 connected to the first piezoelectric element 121. Further, the detection circuit 37 detects the load by detecting the amplitude change of the second vibration waveform Sb obtained via the detection line 13 connected to the second piezoelectric element 122. In the embodiment of FIG. 1, the detection circuit 37 first performs frequency decomposition of the detection waveform S obtained via the detection line 13 commonly connected to the first piezoelectric element 121 and the second piezoelectric element 122. The vibration waveform Sa and the second vibration waveform Sb of the above are extracted (see FIG. 4). The first vibration waveform Sa has a lower frequency than the second vibration waveform Sb.

Since the vibration generated in the vibrating unit 10 propagates to the metal support member 41, the vibration is detected by the second piezoelectric element 122 installed in the support member 41. When the object is placed on the seat cushion 44, the vibration waveform propagating to the support member 41 in contact with the seat cushion 44 changes according to the load. Therefore, the detection circuit 37 determines the presence or absence of an object on the seat cushion 44 and the seat cushion based on the amplitude change of the second vibration waveform Sb obtained via the detection line 13 connected to the second piezoelectric element 122. It is possible to detect the load of an object existing on the 44.

On the other hand, when the object in contact with the seat cushion 44 is a living body, biological signals such as respiration and pulse of the living body are detected by the first piezoelectric element 121 installed on the seat cushion 44. Therefore, the detection circuit 37 detects whether or not the frequency of the first vibration waveform Sa obtained via the detection line 13 connected to the first piezoelectric element 121 matches the frequency of the biological signal. It is possible to detect whether or not the object on the seat cushion 44 is a living body. Since the frequency of the drive signal D is set sufficiently higher than the frequency of the biological signal, the detection circuit 37 does not erroneously detect the frequency of the drive signal D as the frequency of the biological signal.

Therefore, according to the occupant detection device 100 in the present embodiment, both load detection and biological detection can be performed, so that not only can the presence / absence and load of an object on the seat cushion 44 be detected, but also whether or not the object is a living body. It is possible to separate the objects. Further, since the load is detected by applying a predetermined vibration to the support member 41 by the vibrating unit 10 and detecting the change in the amplitude of the vibration, the influence of external noise (for example, road noise or engine vibration) is affected. It is difficult to receive and can continuously perform highly accurate load detection. In this way, since the load detection and the biological detection can be performed with high accuracy, the occupant can be detected with high accuracy.

Next, a configuration example of the occupant detection device 100 according to the present embodiment will be described in more detail.

In the form shown in FIG. 1, the detection circuit 37 includes an amplification unit 32, an A / D (Analog to Digital) conversion unit 33, a signal processing unit 34, and an arithmetic processing unit 36. The amplification unit 32 amplifies the detection waveform S input from the detection line 13, and supplies the amplified detection waveform S to the A / D conversion unit 33. The A / D conversion unit 33 converts the analog detection waveform S supplied from the amplification unit 32 into a digital detection waveform S. The signal processing unit 34 extracts the first vibration waveform Sa and the second vibration waveform Sb whose frequency is higher than that of the first vibration waveform Sa by frequency-decomposing the digital detection waveform S.

The arithmetic processing unit 36 performs biological detection based on the first vibration waveform Sa, and performs load detection based on the second vibration waveform Sb. The arithmetic processing unit 36 detects whether or not the object on the seat cushion 44 is a living body by detecting whether or not the frequency of the first vibration waveform Sa matches the frequency of the biological signal. The arithmetic processing unit 36 detects the presence or absence of an object on the seat cushion 44 and the load of the object existing on the seat cushion 44 based on the amount of change in the amplitude of the second vibration waveform Sb.

When the biological signal is detected by the biological detection based on the first vibration waveform Sa, the arithmetic processing unit 36 restrains the signal A corresponding to the load value obtained by the load detection based on the second vibration waveform Sb. Output to the control device that controls the device. On the other hand, the arithmetic processing unit 36 does not output the signal A to the control device when the biological signal is not detected by the biological detection based on the first vibration waveform Sa. As a result, the control device can perform appropriate occupant restraint control according to the weight of the occupant on the seat cushion 44. Further, when the object on the seat cushion 44 is a non-living object, it is possible to prevent the control device from malfunctioning the occupant restraint device. Specific examples of the occupant restraint device include airbags and seat belts.

Note that some or all of the functions of the detection circuit 37 are realized, for example, by operating the CPU (Central Processing Unit) by a program readable and stored in the memory.

FIG. 5 is a diagram illustrating a change in amplitude of the second vibration waveform due to a load. As for the amplitude of the second vibration waveform Sb for load detection, the maximum amplitude V1 is detected when the load is not applied to the support member 41 (load M1 = 0 kg). When a load is applied to the seat cushion 44, the support member 41 is pressed by the seat cushion 44, so that the vibration propagating to the support member 41 is suppressed by the vibrating portion 10, and the amplitude of the second vibration waveform Sb is attenuated. Since the amplitude of the second vibration waveform Sb is attenuated as the load increases, it is possible to perform load detection using this damping characteristic.

When the load M of the object on the seat cushion 44 becomes large as M1, M2, M3, the amplitude V of the second vibration waveform Sb becomes small as V1, V2, V3. For example, a threshold value Vth is set between V1 and V3. In this case, when the amplitude V is Vth or more and V1 or less, the arithmetic processing unit 36 outputs a signal A indicating that the load M is smaller than the reference value, and the arithmetic processing unit 36 outputs the signal A in which the amplitude V is V3 or more and Vth or less. In this case, a signal A indicating that the load M is larger than the reference value is output. A plurality of threshold values Vth having different levels may be set. Thereby, for example, the arithmetic processing unit 36 can determine whether the occupant on the seat cushion 44 is a child or an adult, and can provide the determination result to the control device controlling the occupant restraint device by the signal A.

The support member 41 on which the second piezoelectric element 122 is installed may be a plate-shaped sheet pan, but is an S spring that is more easily bent than the sheet pan in that it facilitates detection of an amplitude change of the second vibration waveform Sb. Is preferable. The S spring functions as a spring among the seat parts, and the cushioning property is ensured by the combination of the S spring and the seat cushion. When a load is applied to the seat cushion, the S spring gradually bends, and the vibration propagating to the support member 41 can be suppressed stepwise by the vibrating portion 10. As a result, the damping characteristic of the amplitude of the second vibration waveform Sb with respect to the load can be brought close to linear, and the accuracy of the load detection is improved.

FIG. 6 is a diagram showing an example of attaching the first piezoelectric element to the seat cushion. The first piezoelectric element 121 shown in FIG. 6 is a piezoelectric line meanderingly attached to the seat trim 42 of the seat cushion 44. By meandering the piezoelectric line, it is possible to detect the living body even if the occupant is displaced. For example, it is preferable to meander the piezoelectric lines at regular intervals G so that even if the buttocks slide on the seat cushion 44, biological detection is possible. The meandering direction may be the front-rear direction in the vehicle or the left-right direction in the vehicle.

The piezoelectric line is a flexible piezoelectric element that uses a polymer piezoelectric material, and outputs a voltage signal of a magnitude corresponding to the applied tension. The piezoelectric line is laid on the front surface or the back surface of the seat trim 42, and detects a weak movement (vibration) of the human body surface.

The first piezoelectric element 121 is not limited to the piezoelectric line attached to the seat trim 42 covering the cushion pad 43, but is attached to another base material (for example, a heater for warming the buttocks of a person) that covers the cushion pad 43. It may be a piezoelectric line.

FIG. 7 is a diagram showing an example of attaching a load sensor for load detection to an S spring. FIG. 8 is a diagram showing a configuration example of the load sensor. The load sensor 17 shown in FIGS. 7 and 8 includes a vibrating portion 10 and a second piezoelectric element 122. It is preferable to select a position where the load sensor 17 is attached to the S spring 41e so that wiring on the S spring 41e is easy and the wiring length is relatively short. As the distance between the vibrating unit 10 and the second piezoelectric element 122 increases, the amplitude of the vibration waveform output from the second piezoelectric element 122 becomes smaller. Therefore, the vibrating unit 10 and the second piezoelectric element 122 are separated from each other. , It is preferable to make them as close as possible to each other. Therefore, the second piezoelectric element 122 can be attached to the S spring 41e in one package with the vibrating portion 10 to stabilize the output signal of the second piezoelectric element 122.

The second piezoelectric element 122 is preferably a piezoelectric line that can be easily handled from the viewpoint of facilitating attachment to the S spring 41e that meanders continuously to the left and right. Further, in order to prevent the amplitude of the second vibration waveform Sb from becoming excessively small, the second piezoelectric element 122 is an S spring to which the vibrating portion 10 is attached among the plurality of S springs 41e supporting the seat cushion 44. It is preferably attached to 41e. That is, it is preferable that the second piezoelectric element 122 and the vibrating portion 10 are attached to the same S spring 41e.

In the form shown in FIG. 8, the vibrating portion 10 and the second piezoelectric element 122 are adhered to one surface of the double-sided adhesive film 14. By adhering the other surface of the double-sided adhesive film 14 to the S spring 41e, the vibrating portion 10 and the second piezoelectric element 122 can be fixed to the S spring 41e. The drive line 11 is a signal line through which the drive signal D that vibrates the vibrating unit 10 passes. The detection line 13 is a signal line through which the second vibration waveform Sb passes. The ground wire 12 connects the grounds of the vibrating portion 10 and the second piezoelectric element 122 with the grounds of the drive circuit 31 that outputs the drive signal D.

FIG. 9 is a diagram showing a first specific mounting example of the first piezoelectric element. In the form shown in FIG. 9, the first piezoelectric element 121 is a piezoelectric line sewn with a thread 46 at a plurality of locations on the back side of the seat trim 42. By sewing to the seat trim 42, the first piezoelectric element 121 can be firmly fixed to the seat trim 42, and the disturbance of the first vibration waveform Sa can be suppressed.

FIG. 10 is a diagram showing a second specific mounting example of the first piezoelectric element. FIG. 11 is a diagram showing a third specific mounting example of the first piezoelectric element. In the form shown in FIGS. 10 and 11, the first piezoelectric element 121 is a piezoelectric line attached to the cushion pad 43. By attaching to the cushion pad 43 having cushioning properties, the first piezoelectric element 121 is buried in the cushion pad 43, so that the feeling of foreign matter on the buttocks due to the attachment of the first piezoelectric element 121 can be reduced or eliminated. In the form shown in FIG. 10, the first piezoelectric element 121 is laminated with the film 47 along the meandering first piezoelectric element 121, and is attached to the cushion pad 43 with double-sided tape. In the form shown in FIG. 11, the entire meandering first piezoelectric element 121 is laminated with a film 47 and attached to the cushion pad 43 with double-sided tape.

In the form shown in FIGS. 10 and 11, the cushion pad 43 has a groove 48 that accommodates a part or all of the first piezoelectric element 121. By accommodating it in the groove 48, it is possible to reduce or eliminate the feeling of foreign matter on the buttocks due to the attachment of the first piezoelectric element 121. If the groove 48 is a hanging groove for suspending the seam allowance of the seat trim 42, the first piezoelectric element 121 can be pressed into the groove 48 by the seam allowance of the seat trim 42, so that the first piezoelectric element 121 is cushioned. Can be firmly fixed to the pad 43.

FIG. 12 is a cross-sectional view showing a first specific mounting example of the vibrating portion and the second piezoelectric element. The vibrating portion 10 and the second piezoelectric element 122 are molded with an epoxy resin 18 and adhered to the curved surface of the S spring 41e by an adhesive member 15 such as a double-sided tape or an adhesive.

FIG. 13 is a cross-sectional view showing a second specific mounting example of the vibrating portion and the second piezoelectric element. The vibrating portion 10 and the second piezoelectric element 122 are molded with an epoxy resin 18 and are attached to a metal or resin clip 16 with an adhesive member such as double-sided tape or an adhesive. By attaching the clip 16 to which the vibrating portion 10 and the second piezoelectric element 122 are attached to the S spring 41e, the vibrating portion 10 and the second piezoelectric element 122 can be fixed to the S spring 41e with one touch.

FIG. 14 is a diagram showing a first wiring example in which the first vibration waveform and the second vibration waveform are acquired via a common detection line. The control device 30 is an ECU having a drive circuit 31 and a detection circuit 37 (see FIG. 1). The control device 30 has

terminals

131, 132, 133.

15 and 16 are diagrams showing details of the first wiring example shown in FIG. The drive line 11 connected to the drive signal output unit of the drive circuit 31 via the terminal 131 is connected to the drive signal input unit of the vibration unit 10. The ground wire 12 connected to the ground of the drive circuit 31 and the detection circuit 37 via the terminal 132 is connected to the ground of the first piezoelectric element 121 via the ground wire 12a, and is connected to the ground of the first piezoelectric element 121 via the ground wire 12b. And is connected to each ground of the second piezoelectric element 122. The detection line 13 connected to the signal input unit of the detection circuit 37 via the terminal 133 is connected to the signal output unit of the first piezoelectric element 121 via the detection line 13a, and is connected to the signal output unit of the first piezoelectric element 121 via the detection line 13b. It is connected to the signal output section of the piezoelectric element 122.

FIG. 17 is a diagram showing a second wiring example in which the first vibration waveform and the second vibration waveform are acquired via separate detection lines. The control device 30 has

terminals

131, 132, 133a, 133b. The detection circuit 37 performs biological detection by detecting the first vibration waveform Sa via the detection line 13a connected to the first piezoelectric element 121, and the detection line 13b connected to the second piezoelectric element 122. The load is detected by detecting the second vibration waveform Sb via the above. The detection line 13a connects the signal output unit of the first piezoelectric element 121 and the terminal 133a into which the first vibration waveform Sa is input. The detection line 13b connects the signal output unit of the second piezoelectric element 122 and the terminal 133b to which the second vibration waveform Sb is input.

FIG. 18 is a diagram showing a configuration example of a piezoelectric line. The above-mentioned piezoelectric line has, for example, the same structure as the piezoelectric line 20 shown in FIG. The piezoelectric line 20 has a coaxial structure including an inner conductor 26, a piezoelectric material 25 surrounding the inner conductor 26, and an outer conductor 24 surrounding the piezoelectric material 25. A voltage signal corresponding to the load applied to the piezoelectric line is output from the internal conductor 26. The outer conductor 24 functions as a shield against noise.

Although the occupant detection device and the seat have been described above by the embodiment, the present invention is not limited to the above embodiment. Various modifications and improvements, such as combinations and substitutions with some or all of the other embodiments, are possible within the scope of the present invention.

For example, the number of vibrating portions 10 installed on the support member 41 is not limited to one, and may be plural. Further, the vibration unit 10 is not limited to the piezoelectric element, and may be another vibration generator such as a vibration motor or a vibration actuator. The vibrating unit 10 may be a piezoelectric line that vibrates according to the drive signal D. By using the vibrating portion 10 as a piezoelectric line, the degree of freedom of attachment to the support member 41 is improved.

Further, the vibrating unit 10 may be used for both load detection by vibration and alerting by vibration. That is, when the drive circuit 31 detects the load, the drive circuit 31 vibrates the vibrating portion 10 with a constant amplitude and frequency so that the vibrating portion 10 vibrates with a size such that the occupant on the seat cushion 44 does not feel the vibration. Output the drive signal. On the other hand, in the drive circuit 31, when the occupant on the seat cushion 44 is alerted by vibrating the support member 41, the vibrating portion 10 vibrates to such an extent that the occupant on the seat cushion 44 feels vibration. As a result, a drive signal that vibrates the vibrating unit 10 is output. As a result, the vibrating part for load detection and the vibrating part for calling attention can be shared, so that the circuit configuration is simplified. For example, vibration alerting is performed when an event that should alert the occupant, such as falling asleep, lane departure, or vehicle collision prediction, is detected.

The piezoelectric element is not limited to the piezoelectric line, but may be a strip-shaped piezoelectric film.

This international application claims priority based on Japanese Patent Application No. 2019-137168 filed on July 25, 2019, and the entire contents of Japanese Patent Application No. 2019-137168 are included in this international application. Invite to.

10 Vibrating part 11 Drive line 12 Ground line 13 Detection line 14 Double-sided adhesive film 15 Adhesive member 16 Clip 17 Load sensor 18 Epoxy resin 20 Piezoelectric line 24 External conductor 25 Piezoelectric material 26 Internal conductor 40 Sheet 41 Support member 41e S spring 42 Seat trim 43 Cushion pad 44 Seat cushion 45 Seat back 46 Thread 47 Film 48 Groove 121 First piezoelectric element 122 Second piezoelectric element S Detection waveform Sa First vibration waveform Sb Second vibration waveform

Claims

A vibrating part installed on a metal support member that supports the seat cushion from below,
The first piezoelectric element installed on the seat cushion and
A second piezoelectric element installed on the support member and
A drive circuit that outputs a drive signal that vibrates the vibrating portion so that the vibration propagates to the support member.
Biometric detection is performed by detecting a first vibration waveform whose frequency is lower than that of the drive signal via a detection line connected to the first piezoelectric element, and a detection line connected to the second piezoelectric element. An occupant detection device including a detection circuit that detects a load by detecting an amplitude change of a second vibration waveform obtained through the device.
The detection circuit frequency-decomposes a detection waveform obtained via a detection line commonly connected to the first piezoelectric element and the second piezoelectric element, thereby causing the first vibration waveform and the second vibration waveform. The occupant detection device according to claim 1, which extracts the vibration waveform of the above.
The occupant detection device according to claim 1, wherein the first piezoelectric element is a piezoelectric line meanderingly attached to the seat cushion.
The seat cushion has a cushion pad that is supported from below by the support member, and a base material that covers the cushion pad.
The occupant detection device according to claim 1, wherein the first piezoelectric element is a piezoelectric line attached to the base material.
The occupant detection device according to claim 4, wherein the first piezoelectric element is sewn on the base material.
The occupant detection device according to claim 5, wherein the base material is a seat trim.
The seat cushion has a cushion pad that is supported from below by the support member, and a seat trim that covers the cushion pad.
The occupant detection device according to claim 1, wherein the first piezoelectric element is a piezoelectric line attached to the cushion pad.
The occupant detection device according to claim 7, wherein the cushion pad has a groove for accommodating the first piezoelectric element.
The occupant detection device according to claim 8, wherein the groove is a hanging groove for suspending the seam allowance of the seat trim.
The support member has an S spring and has an S spring.
The occupant detection device according to claim 1, wherein the second piezoelectric element is a piezoelectric line attached to the S spring.
The occupant detection device according to claim 10, wherein the second piezoelectric element is attached to the S spring to which the vibrating portion is attached.
The occupant detection device according to claim 11, wherein the second piezoelectric element is attached to the S spring in one package with the vibrating portion.
The occupant detection device according to claim 1, wherein the vibrating unit is a piezoelectric line that vibrates according to the drive signal.
When the biological signal is detected by the biological detection, the detection circuit outputs a signal corresponding to the load value obtained by the load detection to the control device that controls the occupant restraint device, and the biological detection causes the biological signal. The occupant detection device according to claim 1, wherein when the signal is not detected, the signal is not output to the control device.
With a seat cushion
A metal support member that supports the seat cushion from below, and
The vibrating part installed on the support member and
The first piezoelectric element installed on the seat cushion and
A second piezoelectric element installed on the support member and
A drive circuit that outputs a drive signal that vibrates the vibrating portion so that the vibration propagates to the support member.
Biometric detection is performed by detecting a first vibration waveform whose frequency is lower than that of the drive signal via a detection line connected to the first piezoelectric element, and a detection line connected to the second piezoelectric element. A sheet including a detection circuit that detects a load by detecting an amplitude change of a second vibration waveform obtained via the above.