JP7272890B2 - Occupant detection device and seat - Google Patents

Description

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

2. Description of the Related Art Conventionally, there has been known a biometric information detection device that includes a sensor composed of a piezoelectric element that is placed at a location that comes into direct or indirect contact with a human body, and detects biometric information of the human body and estimates the mass from the output of this sensor. (See Patent Document 1, for example).

JP-A-2001-204694

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

Accordingly, the present disclosure provides an occupant detection device and a seat that can detect an occupant with high accuracy.

This disclosure is
a vibrating unit installed on a metal support member that supports the seat cushion from below;
a first piezoelectric element installed on the seat cushion;
a second piezoelectric element installed on the support member;
a driving circuit for outputting a driving signal for vibrating the vibrating portion so that the vibration is propagated to the supporting member;
A living body is detected by detecting a first vibration waveform having a frequency 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. and a detection circuit that detects a load by detecting a change in the amplitude of a second vibration waveform obtained through the .

This disclosure also provides
seat cushion and
a metal support member that supports the seat cushion from below;
a vibrating portion installed on the support member;
a first piezoelectric element installed on the seat cushion;
a second piezoelectric element installed on the support member;
a driving circuit for outputting a driving signal for vibrating the vibrating portion so that the vibration is propagated to the supporting member;
A living body is detected by detecting a first vibration waveform having a frequency 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. and a sensing circuit that senses a load by detecting a change in the amplitude of a second vibration waveform obtained through.

According to the technique of the present disclosure, it is possible to provide an occupant detection device and a seat that can detect an occupant with high accuracy.

1 is a block diagram showing a configuration example of an occupant detection system; FIG. 1 is a diagram schematically showing a configuration example of an occupant detection system; FIG. FIG. 4 is an exploded perspective view showing a configuration example of a seat cushion and a support member; It is a figure which illustrates a 1st vibration waveform and a 2nd vibration waveform. It is a figure which illustrates the amplitude change of the 2nd vibration waveform by load. It is a figure which shows the example of attachment to a seat cushion of a 1st piezoelectric element. It is a figure which shows the example of attachment to S spring of the load sensor for load detection. It is a figure which shows the structural example of a load sensor. FIG. 4 is a diagram showing a first specific example of attachment of the first piezoelectric element; FIG. 10 is a diagram showing a second specific example of attachment of the first piezoelectric element; FIG. 10 is a diagram showing a third specific example of attachment of the first piezoelectric element; FIG. 4 is a cross-sectional view showing a first specific example of attachment of the vibrating portion and the second piezoelectric element; FIG. 10 is a cross-sectional view showing a second specific example of attachment of the vibrating portion and the second piezoelectric element; It is a figure which shows the 1st wiring example which acquires a 1st vibration waveform and a 2nd vibration waveform via a common detection line. FIG. 4 is a diagram showing details of a first wiring example; FIG. 4 is a diagram showing in detail a first wiring example; FIG. 10 is a diagram showing a second wiring example for acquiring a first vibration waveform and a second vibration waveform via separate detection lines; It is a figure which shows the structural example of a piezoelectric line.

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

FIG. 1 is a block diagram showing a configuration example of an occupant detection system according to an embodiment of the present disclosure. The occupant detection system shown in FIG. 1 detects an occupant sitting on a seat 40 mounted in a vehicle, and outputs the detection result to an external device. This occupant detection system includes a seat 40 installed in a 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 an occupant detection system according to an 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 that supports the buttocks and thighs of the occupant sitting on the seat 40 from below. The seat surface of the seat cushion 44 contacts 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 supported by the support member 41 from below. The cushion pad 43 is made of, for example, urethane foam. The seat trim 42 is a base material that covers the cushion pad 43 and forms the seat surface of the seat cushion 44 . The seat trim 42 is, for example, an upholstery member made of cloth 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 behind. A backrest surface of the seat back 45 contacts the back of the passenger 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 a seat cushion and a support member. The seat cushion 44 has a cushion pad 43 having cushioning properties and a seat trim 42 placed 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 lateral 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 41 e is an example of a cushion supporting portion that supports the seat cushion 44 from below and contacts the lower surface of the cushion pad 43 . The S spring 41e is an elastic wire made of metal in which an S-shaped portion is repeatedly continuous.

FIG. 3 illustrates a configuration in which a plurality of S springs 41e arranged in the left-right direction are installed between the front frame 41c and the rear frame 41d. may be installed between the pair of side frames 41a and 41b.

In FIG. 1 , the occupant detection device 100 includes a vibrating section 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 section 10 is installed on a metal support member 41 that supports the seat cushion 44 from below, for example, on a cushion support section such as the S spring 41e described above. The vibrating section 10 is connected to the drive circuit 31 via the drive line 11 .

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

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

The drive circuit 31 supplies a drive signal D to the vibrating section 10 through the drive line 11 to vibrate the vibrating section 10 with a magnitude that causes the vibration to propagate to the support member 41 . The drive circuit 31 generates a drive signal D for vibrating the vibrating portion 10 so that the vibrating portion 10 vibrates at a magnitude that does not cause the occupant on the seat cushion 44 to feel the vibration during the period in which the living body detection and the load detection are performed. Output. A waveform (driving waveform) of the drive signal D has a constant amplitude and a constant frequency (eg, 5 kHz). The drive waveform may be a square wave or a sine wave.

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

The detection circuit 37 detects a living body by detecting a first vibration waveform Sa whose frequency is lower than that of 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 through the detection line 13 connected to the second piezoelectric element 122 . In the form of FIG. 1, the sensing circuit 37 frequency-resolves the sensing waveform S obtained via the sensing line 13 commonly connected to the first piezoelectric element 121 and the second piezoelectric element 122 to obtain the first and the second vibration waveform Sb are extracted (see FIG. 4). The first vibration waveform Sa has a lower frequency than the second vibration waveform Sb.

The vibration generated by the vibrating section 10 propagates to the metal support member 41 , so the vibration is detected by the second piezoelectric element 122 installed on the support member 41 . When an 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 detects the existence or non-existence of an object on the seat cushion 44 based on the amplitude change of the second vibration waveform Sb obtained through the detection line 13 connected to the second piezoelectric element 122, and detects the presence or absence of the seat cushion. The load of an object present on 44 can be sensed.

On the other hand, if the object in contact with the seat cushion 44 is a living body, the biological signals of the living body such as respiration and pulse 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 through the detection line 13 connected to the first piezoelectric element 121 matches the frequency of the biosignal. It can be detected whether 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 biosignal, the detection circuit 37 does not erroneously detect the frequency of the drive signal D as the frequency of the biosignal.

Therefore, according to the occupant detection device 100 of the present embodiment, both load detection and living body detection can be performed. It is possible to perform the division of In addition, since the load is detected by applying a predetermined vibration to the support member 41 by the vibrating section 10 and detecting the amplitude change of the vibration, the influence of external noise (for example, road noise, engine vibration, etc.) can be eliminated. Highly accurate load detection can be carried out continuously. In this way, load detection and living body detection can be performed with high accuracy, so the occupant can be detected with high accuracy.

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

In the form shown in FIG. 1 , the detection circuit 37 has an amplifier section 32 , an A/D (Analog to Digital) conversion section 33 , a signal processing section 34 and an arithmetic processing section 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 section 33 converts the analog detection waveform S supplied from the amplification section 32 into a digital detection waveform S. FIG. The signal processing unit 34 extracts a first vibration waveform Sa and a second vibration waveform Sb having a higher frequency than the first vibration waveform Sa by frequency-decomposing the digital detection waveform S.

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

Some or all of the functions of the detection circuit 37 are realized by, for example, a CPU (Central Processing Unit) operating by a program stored in a memory so as to be readable.

FIG. 5 is a diagram illustrating amplitude changes of the second vibration waveform due to load. As for the amplitude of the second vibration waveform Sb for load detection, the maximum amplitude V1 is detected when no load is applied to the support member 41 (load M1=0 kg). Since the support member 41 is pressed by the seat cushion 44 when a load is applied to the seat cushion 44, the vibration propagating to the support member 41 is suppressed by the vibrating section 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 detect the load using this attenuation characteristic.

When the load M of the object on the seat cushion 44 increases to M1, M2 and M3, the amplitude V of the second vibration waveform Sb decreases to V1, V2 and V3. For example, a threshold Vth is set between V1 and V3. In this case, if the amplitude V is greater than or equal to Vth and less than or equal to V1, the arithmetic processing section 36 outputs a signal A indicating that the load M is smaller than the reference value. In this case, it outputs a signal A indicating that the load M is greater than the reference value. A plurality of threshold values Vth with different levels may be set. As a result, 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 as a signal A to the control device that controls the occupant restraint system.

The support member 41 on which the second piezoelectric element 122 is installed may be a plate-shaped seat pan. is preferred. The S spring functions as a spring in the seat component, and the combination of the S spring and the seat cushion ensures cushioning properties. When a load is applied to the seat cushion, the S spring is gradually bent, and the vibration propagating to the support member 41 can be suppressed step by step by the vibrating portion 10 . As a result, the attenuation 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 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 attached to the seat trim 42 of the seat cushion 44 in a meandering manner. By meandering the piezoelectric line, it is possible to detect the living body even if the occupant is seated out of alignment. For example, it is preferable to meander the piezoelectric line at a constant interval G so that the living body can be detected even if the buttocks slide on the seat cushion 44 . The meandering direction may be the front-rear direction of the vehicle or the left-right direction of the vehicle.

A piezoelectric line is a flexible piezoelectric element that uses a polymeric piezoelectric material, and outputs a voltage signal whose magnitude corresponds to the applied tension. The piezoelectric line is laid on the front or back surface of the seat trim 42 and detects weak movements (vibrations) of the human body surface.

Note that the first piezoelectric element 121 is not limited to the piezoelectric line attached to the seat trim 42 covering the cushion pad 43, and is attached to another base material covering the cushion pad 43 (for example, a heater for warming a person's buttocks). A piezoelectric line may be used.

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 a load sensor. A 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. The amplitude of the vibration waveform output from the second piezoelectric element 122 decreases as the distance between the vibrating section 10 and the second piezoelectric element 122 increases. , preferably adjacent to each other as closely as possible. Therefore, the second piezoelectric element 122 can stabilize the output signal of the second piezoelectric element 122 by attaching the second piezoelectric element 122 to the S spring 41e as one package with the vibrating section 10 .

The second piezoelectric element 122 is preferably a flexible piezoelectric line in that it can be easily attached to the S spring 41e that continuously meanders 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 the S spring to which the vibrating portion 10 is attached, among the plurality of S springs 41e that support 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 section 10 and the second piezoelectric element 122 are adhered to one surface of the double-sided adhesive film 14 . By bonding the other surface of the double-sided adhesive film 14 to the S spring 41e, the vibrating section 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 a drive signal D for vibrating the vibrating section 10 passes. The detection line 13 is a signal line through which the second vibration waveform Sb passes. The ground line 12 connects the ground of each of the vibrating section 10 and the second piezoelectric element 122 and the ground of the drive circuit 31 that outputs the drive signal D. As shown in FIG.

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 threads 46 at multiple points 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 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 second specific mounting example of the first piezoelectric element. 10 and 11, the first piezoelectric element 121 is a piezoelectric line attached to the cushion pad 43. In the embodiment shown in FIGS. By attaching the first piezoelectric element 121 to the cushion pad 43 having a cushioning property, the first piezoelectric element 121 is buried in the cushion pad 43, so that the feeling of a foreign object 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 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 grooves 48 that accommodate part or all of the first piezoelectric element 121 . By accommodating the first piezoelectric element 121 in the groove 48 , it is possible to reduce or eliminate the feeling of a foreign object on the buttocks due to the attachment of the first piezoelectric element 121 . If the groove 48 is a hanging groove for hanging 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 can be cushioned. It 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 with an adhesive member 15 such as double-sided tape or adhesive.

FIG. 13 is a cross-sectional view showing a second specific attachment 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 attached to the metal or resin clip 16 with an adhesive member such as double-sided tape or 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 for acquiring the first vibration waveform and the second vibration waveform 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 and 133 .

15 and 16 are diagrams showing the details of the first wiring example shown in FIG. A drive line 11 connected to a drive signal output section of the drive circuit 31 via a terminal 131 is connected to a drive signal input section of the vibrating section 10 . The ground line 12 connected to the grounds of the drive circuit 31 and the detection circuit 37 via a terminal 132 is connected to the ground of the first piezoelectric element 121 via a ground line 12a, and is connected to the vibrating portion 10 via a ground line 12b. and each ground of the second piezoelectric element 122 . The detection line 13 connected to the signal input portion of the detection circuit 37 via the terminal 133 is connected to the signal output portion of the first piezoelectric element 121 via the detection line 13a and the second 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 for acquiring the first vibration waveform and the second vibration waveform via separate detection lines. The control device 30 has terminals 131, 132, 133a and 133b. The detection circuit 37 detects the living body by detecting the first vibration waveform Sa through the detection line 13a connected to the first piezoelectric element 121, and the detection line 13b connected to the second piezoelectric element 122. Load detection is performed by detecting the second vibration waveform Sb via the . The detection line 13a connects the signal output portion of the first piezoelectric element 121 and a terminal 133a to which the first vibration waveform Sa is input. The detection line 13b connects the signal output portion 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 piezoelectric line described above has, for example, the same structure as the piezoelectric line 20 shown in FIG. Piezoelectric line 20 has a coaxial structure comprising an inner conductor 26 , a piezoelectric material 25 surrounding inner conductor 26 , and an outer conductor 24 surrounding piezoelectric material 25 . A voltage signal corresponding to the load applied to the piezoelectric line is output from the inner conductor 26 . The outer conductor 24 functions as a shield against noise.

Although the occupant detection device and the seat have been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements such as combination or replacement with part or all of other embodiments are possible within the scope of the present invention.

For example, the number of vibration units 10 installed on the support member 41 is not limited to one, and may be plural. Further, the vibrating section 10 is not limited to a piezoelectric element, and may be other vibration generators such as a vibration motor and a vibration actuator. The vibrating section 10 may be a piezoelectric line vibrated by the driving signal D. FIG. By using the piezoelectric line as the vibrating section 10, the degree of freedom in attachment to the support member 41 is improved.

Further, the vibrating section 10 may be used both for load detection by vibration and for alerting by vibration. That is, when detecting a load, the drive circuit 31 vibrates the vibrating section 10 at a constant amplitude and frequency so that the vibrating section 10 vibrates at a magnitude that does not cause the occupant on the seat cushion 44 to feel the vibration. Outputs the drive signal. On the other hand, when the drive circuit 31 vibrates the support member 41 to alert the occupant on the seat cushion 44, the vibrating portion 10 vibrates with a magnitude that causes the occupant on the seat cushion 44 to feel the vibration. , a driving signal for vibrating the vibrating portion 10 is output. As a result, the vibrating section for load detection and the vibrating section for calling attention can be shared, thereby simplifying the circuit configuration. For example, alerting by vibration is performed when an event that should alert the occupant, such as falling asleep, lane departure, or vehicle collision prediction, is detected.

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

10 Vibration part 11 Drive line 12 Ground wire 13 Detection line 14 Double-sided adhesive film 15 Adhesive member 16 Clip 17 Load sensor 18 Epoxy resin 20 Piezoelectric line 24 Outer conductor 25 Piezoelectric material 26 Inner conductor 40 Seat 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 (15)

a vibrating unit installed on a metal support member that supports the seat cushion from below;
a first piezoelectric element installed on the seat cushion;
a second piezoelectric element installed on the support member;
a driving circuit for outputting a driving signal for vibrating the vibrating portion so that the vibration is propagated to the supporting member;
A living body is detected by detecting a first vibration waveform having a frequency 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, comprising: a detection circuit that detects a load by detecting a change in the amplitude of a second vibration waveform obtained through . The detection circuit frequency-decomposes a detection waveform obtained through a detection line commonly connected to the first piezoelectric element and the second piezoelectric element to obtain the first vibration waveform and the second vibration waveform. 2. The occupant detection device according to claim 1, which extracts a vibration waveform of 3. The occupant detection device according to claim 1, wherein said first piezoelectric element is a piezoelectric line meanderingly attached to said seat cushion. The seat cushion has a cushion pad supported from below by the support member and a base material covering the cushion pad,
The occupant detection device according to any one of claims 1 to 3, wherein the first piezoelectric element is a piezoelectric line attached to the base material. 5. The occupant detection device of claim 4, wherein the first piezoelectric element is sewn to the base material. 6. The occupant sensing device of claim 5, wherein the substrate is seat trim. The seat cushion has a cushion pad supported from below by the support member and a seat trim covering the cushion pad,
The occupant detection device according to any one of claims 1 to 3, wherein said first piezoelectric element is a piezoelectric line attached to said cushion pad. 8. The occupant detection device according to claim 7, wherein said cushion pad has a groove for accommodating said first piezoelectric element. The occupant detection device according to claim 8, wherein the groove is a hanging groove for hanging a seam allowance of the seat trim. The support member has an S spring,
The occupant detection device according to any one of claims 1 to 9, wherein said second piezoelectric element is a piezoelectric line attached to said S spring. 11. The occupant detection device according to claim 10, wherein said second piezoelectric element is attached to said S spring to which said vibrating portion is attached. 12. The occupant detection device according to claim 11, wherein said second piezoelectric element is attached to said S spring as one package with said vibrating portion. The occupant detection device according to any one of claims 1 to 12, wherein the vibrating section is a piezoelectric line that vibrates according to the drive signal. When a 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 a control device for controlling the occupant restraint device. 14. The occupant detection system of any one of claims 1 to 13, wherein if no signal is detected, the signal is not output to the controller. seat cushion and
a metal support member that supports the seat cushion from below;
a vibrating portion installed on the support member;
a first piezoelectric element installed on the seat cushion;
a second piezoelectric element installed on the support member;
a driving circuit for outputting a driving signal for vibrating the vibrating portion so that the vibration is propagated to the supporting member;
A living body is detected by detecting a first vibration waveform having a frequency 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. and a sensing circuit that senses a load by detecting a change in the amplitude of the second vibration waveform obtained through.

Images