JP2000025560A - Occupant detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an occupant detection system which is capable of correctly recognizing the occupant seated in a seat whether or not the occupant is an adult or a child, and appropriately controlling an air bag device based on the result of judgment. SOLUTION: An occupant detection system is provided with a plurality of strip-like antenna electrodes arranged on a back part of a seat in an extending manner in the vertical direction with approximately constant intervals in a width direction, an electric field generating means 11 to generate the weak electric field around the antenna electrodes, a current detection circuit 15 to detect the running current based on the electric field generated around a specified antenna electrode, a control circuit 20 which judges whether or not the an occupant is an adult or a child based on the data taken from the current detection circuit, and an air bag device 30 having the function to develop the air bag in the collision, and the air bag of the air bag device is set to either the developing condition or the non-developing condition based on the result of judgment of the control circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an occupant detection system, and more particularly to an occupant capable of setting an airbag device to a predetermined operation mode depending on whether an occupant in a passenger seat of an automobile equipped with the airbag device is an adult or a child. It relates to improvement of a detection system.

[0002]

2. Description of the Related Art Generally, an airbag device is a device for reducing the impact received by an occupant at the time of a collision of an automobile.
It has become indispensable to the safety of automobiles, and has recently been installed not only in the driver's seat but also in the passenger seat.

[0003] In particular, when an airbag device is also installed in the passenger seat, the airbag is deployed at the time of collision regardless of whether or not an occupant is seated in the passenger seat. If the occupant is not seated, the deployment of the airbag becomes meaningless, and repair costs are required to restore it.

Therefore, in order to eliminate such waste,
An occupant detection device may be provided to confirm whether or not the occupant is seated on the sheet, and only when the occupant is not seated, the airbag device may be prevented from deploying even if a collision occurs.

[0005]

As described above, various proposals have been made as occupant detection devices for detecting the presence or absence of an occupant in a seat. For example, JP-A-4-46843, JP-A-3-52266, JP-A-61-11
Japanese Patent No. 3527 discloses an occupant detection device in which a load sensor is incorporated in a sheet. Also, Table 9-5
JP-A-09118 discloses that electrodes are arranged on a seating portion and a backrest portion of a seat, and between electrodes or between a vehicle and a vehicle.
There is disclosed an occupant detection device in which an oscillation circuit is connected between the occupant detection device.

According to the former occupant detection devices, the load sensor reacts when a load acts on the sheet, and the load sensor does not react when no load acts on the sheet. Can be accurately detected by the load sensor. According to the latter occupant detection device,
When an occupant is seated on the seat, the capacitance between the electrodes or between the electrodes and the chassis increases, and when the occupant is not seated on the seat, the capacitance between the electrodes or between the electrodes and the chassis increases. Since the capacitance of the occupant decreases, the presence or absence of the occupant can be accurately detected by detecting the change in the oscillation frequency based on the change in the capacitance. Therefore, when the occupant is not seated in the passenger seat, the deployment operation of the airbag device can be prevented beforehand, and the above waste can be eliminated.

In recent years, when an impact caused by a collision or the like is applied to a vehicle equipped with an airbag device, it is often necessary to finely control the airbag device based on the sitting height of an occupant sitting on a seat. Is desired. For example, if the occupant is a child, the sitting height is usually low, so that even if the vehicle collides, it may be desirable not to deploy the airbag of the airbag device.

However, even if the load sensor and the capacitance detection sensor (electrode) disclosed in the above-mentioned prior art can detect the presence or absence of the occupant, the occupant can be detected based on the sitting height of the occupant. However, there is a problem that it is not possible to accurately detect whether the child is an adult or a child.

Therefore, there is a demand for an occupant detection system that can control the airbag device finely and appropriately according to the sitting height of the occupant.

[0010] Therefore, an object of the present invention is to accurately detect whether an occupant sitting on a seat is an adult or a child, and based on the detection result, to control an airbag device appropriately. It is to provide a system.

[0011]

SUMMARY OF THE INVENTION Therefore, in order to achieve the above-mentioned object, the present invention provides a seat having a plurality of seat backs arranged at substantially constant intervals in the width direction and extending vertically. A band-like antenna electrode, an electric field generating means for generating a weak electric field around the antenna electrode, and selectively generating a weak electric field around a specific antenna electrode among a plurality of antenna electrodes. And a control circuit for determining whether or not the occupant is an adult based on signal data taken from the current detection circuit.

Further, a second invention of the present invention relates to a plurality of strip-shaped antenna electrodes arranged on a backrest portion of a sheet at substantially constant intervals in the width direction and so as to extend vertically. An electric field generating means for generating a weak electric field in the periphery, and a current detection circuit for selectively generating a weak electric field around a specific antenna electrode among the plurality of antenna electrodes and detecting a current flowing based on the electric field A control circuit for determining whether or not the occupant is an adult based on signal data taken from the current detection circuit, and an airbag device having a function of deploying the airbag based on a collision. And transmitting data based on the determination result of the control circuit to the airbag device, and setting the airbag of the airbag device to one of a deployable state and an undeployable state. And it features.

Further, according to a third aspect of the present invention, the control circuit includes at least a threshold data relating to occupant identification.
Storage means for storing data, means for taking in an output signal from the current detection circuit, and comparison between the signal data taken from the current detection circuit and the threshold data to determine whether or not the occupant is an adult. The fourth invention is characterized in that the electric field generating means is selectively connected to a specific antenna electrode among the plurality of strip-shaped antenna electrodes by a switching operation of a switching circuit. Characteristic, 5th
The invention is characterized in that the plurality of strip-shaped antenna electrodes are extended and arranged downward from an upper portion of a seat back portion of the sheet.

[0014]

Next, the basic principle of the present invention will be described. The occupant detection system according to the present invention basically utilizes a weak electric field (Electric Field) generated in an antenna electrode disposed on a sheet. A weak electric field is selectively generated around a plurality of antenna electrodes spaced apart from a backrest, and an occupant is generated based on a current flowing through each antenna electrode based on an electric characteristic of an object located near these antenna electrodes. The present embodiment detects the seating status of the seat (e.g., whether the passenger is an adult or a child).
In particular, by increasing the number of antenna electrodes, it becomes possible to obtain a lot of information about the occupant on the sheet, and the occupant can be detected more accurately.

An embodiment of an occupant detection system according to the present invention utilizing this principle will be described with reference to FIGS. 1 and 2 show the arrangement of a passenger seat and an antenna electrode according to the present invention. The seat 1 mainly includes a seating portion 1a and a backrest portion 1b. The seating section 1a is, for example, a base that can slide back and forth.
A seat frame 3 fixed to the seat 2, a cushion material disposed on the upper portion of the sheet frame 3, and an exterior material covering the cushion material.
For example, a cushioning material is arranged on the front side of the sheet frame, and the cushioning material is covered with an exterior material. In particular, the backrest portion 1b has a plurality of strip-shaped antenna electrodes 4 (4a to 4d) directed downward from the upper portion thereof.
Are arranged at substantially constant intervals in the width direction and extend in the up-down direction. In addition, the antenna electrode 4 can be arranged outside or outside the exterior material, or can be provided on the exterior material itself. Further, a control unit 10 to be described later is arranged in or near the sheet frame 3.

The antenna electrode 4 is made of, for example, a conductive cloth.
, The conductive paint is applied to the cloth surface, or a metal plate is arranged. In particular, as shown in FIG. 2, for example, the antenna electrodes 4 are formed by arranging strip-shaped antenna electrodes 4a to 4d of the same size at predetermined intervals in the width direction on one surface of a base member 5 made of an insulating member. It is desirable to constitute by integrating, and it is arrange | positioned inside the exterior | packing material of the backrest part 1b. A lead wire 6 is connected from the antenna electrodes 4a to 4d.
(6a to 6d) are independently derived, and connectors (or terminals) 19a to 19 of the control unit 10 described later are provided.
d.

A control unit 10 is disposed in the sheet 1 of the sheet 1 or in the vicinity thereof. The control unit 10 has a frequency of about 120 KHz, for example, as shown in FIG. Electric field generating means (for example, an oscillation circuit) 1 for outputting a high frequency low voltage of about 5 to 12 V and generating a weak electric field around the antenna electrode 4
1, an amplitude control circuit 12 for controlling the voltage amplitude of the transmission signal from the oscillation circuit 11 to be substantially constant, a current detection circuit 15 for detecting the transmission current of the transmission signal, and converting the output signal of the current detection circuit 15 to DC. AC-DC conversion circuit 16
Amplifier 17 for amplifying the output signal of C-DC conversion circuit 16
And the antenna electrodes 4a to 4d connected to the current detection circuit 15 and having a plurality of switching means 18a to 18d.
d, a switching circuit 18 and connectors 19a to 19d connected to switching means 18a to 18d of the switching circuit 18 and arranged in a housing of the control unit;
A control circuit 20 including an external memory and the like; a connector 21 arranged in the housing and connected to a battery power supply (not shown); a power supply circuit 22 connected to the connector 21 and generating a power supply required by components of the control unit; It is composed of An airbag device 30 is connected to the control circuit 20 of the control unit 10. The switching operation of the switching circuit 18 (switching means 18a to 18d) is performed based on a signal from the control circuit 20.

In the control unit 10, the amplitude control circuit 12 includes, for example, an amplitude variable circuit 13 for varying the voltage amplitude of the transmission signal and an amplitude detection circuit 14 for detecting the voltage amplitude of the transmission signal. The variable amplitude circuit 13 includes, for example, a programmable gain amplifier (PG
A), the amplitude detection circuit 14 includes a voltage amplitude detection unit 14a such as an operational amplifier, and an AC-DC conversion circuit 14b that converts an output signal of the detection unit 14a into a direct current. And an amplifier 14c for amplifying the output signal of the AC-DC conversion circuit 14b. The output signal of the amplifier 14c is supplied to the control circuit 20, and the variable amplitude signal for the variable amplitude section 13a is output from the control circuit 20.

In the control unit 10, the current detection circuit 15 includes, for example, an impedance element such as a resistor 15a connected in series to a circuit (transmission signal system), and a differential amplifier for amplifying a terminal voltage of the resistor 15a. Amplifier 1 such as
5b. The output side of the current detection circuit 15 is connected to a control circuit 20 via an AC-DC conversion circuit 16 and an amplifier 17. And the current detection circuit 1
5, the output side of the resistor 15a is connected to the connectors 19a to 19d via the switching circuit 18.

The occupant detection system thus configured operates as follows. First, when a high-frequency low voltage is transmitted from the oscillation circuit 11, the voltage amplitude thereof is detected by the detection unit 14a of the amplitude detection circuit 14, and the detection signal is A
The direct current is converted by the C-DC conversion circuit 14b to the
The signal is amplified at 4c and input to the control circuit 20. The control circuit 20 determines whether or not the detected voltage amplitude has a predetermined amplitude value, and outputs an amplitude variable signal for correcting the detected voltage amplitude to the predetermined voltage amplitude to the amplitude variable section 13a. Thereby, the voltage amplitude of the transmission signal is corrected to a predetermined amplitude,
Thereafter, the amplitude is controlled to be constant by the cooperative operation of the amplitude variable circuit 13 and the amplitude detection circuit 14.

The transmission signal having a constant voltage amplitude is supplied to the antenna electrode 4 via the current detection circuit 15, the switching circuit 18, and the connectors 19a to 19d. As a result, a weak electric field is generated around the antenna electrode 4. Is done. At this time, switching of the switching circuit 18 is controlled by a signal from the control circuit 20. That is, first, only the switching means 18a is closed, then only the switching means 18b is closed, and so on, only the specific switching means is sequentially closed, and the other switching means are opened at the same time. Is selectively controlled as described above. Therefore, when the specific switching means is closed, the transmission signal whose voltage amplitude is fixed is transmitted to the current detection circuit 15, the specific switching means 18a to 18d, and the specific connectors 19a to 1d.
9d, the electric power is supplied to specific antenna electrodes 4a to 4d. As a result, a weak electric field is generated around the specific antenna electrodes 4a to 4d, depending on the seating posture of the occupant sitting on the seat 1. Different levels of current flow. That is, a current flows according to the difference in the dielectric constant of the back, shoulder, neck, and head of the occupant. This current is detected by the current detection circuit 15, converted into a direct current by the AC-DC conversion circuit 16, amplified by the amplifier 17, and input to the control circuit 20 one after another.

In the control circuit 20, threshold values (threshold data) TH1 and TH2 relating to the identification of the occupant (the distinction between an adult and a child) are stored in the storage means in advance. . These threshold values TH1 and TH2 exhibit characteristic patterns in signal data relating to currents flowing through the respective antenna electrodes in relation to differences in sitting height and shoulder width between adults and children. It is set based on. That is, the level of the current flowing through each of the antenna electrodes 4a to 4d is different depending on the sitting height and the shoulder width, and the higher the sitting height and the wider the shoulder width like an adult, the more the antenna electrodes 4a to 4d.
The characteristic pattern that the level of the current flowing through d increases and the level of the current decreases as the sitting height decreases and the shoulder width decreases as in a child, and the current does not easily flow through a specific antenna electrode. Appears.

For example, regarding the threshold value TH1, when the adult occupant P is normally seated on the seat, FIG.
As shown in FIG. 4B, even if the level of the current flowing through all the antenna electrodes 4a to 4d increases, and the occupant P falls down and leans to one side, the antenna electrodes Since the levels of the currents flowing through 4b to 4d tend to be high, the signal data relating to the currents flowing through two or more, for example, three or more, antenna electrodes adjacent to each other are obtained.
The average arbitrary value of the threshold value is set as the threshold value TH1. Note that this average arbitrary value can be appropriately changed according to the situation. Therefore, if the signal data relating to the current flowing through the three or more antenna electrodes is larger than the threshold data TH1, the occupant is determined to be an adult.

On the other hand, regarding the threshold value TH2, when the occupant SP of the child is normally seated on the seat, FIG.
As shown in (a), when the current flowing through the antenna electrodes 4b and 4c is higher than the level of the current flowing through the other antenna electrodes 4a and 4d, and when the occupant SP falls down and leans to one side, As shown in FIG. 3B, the level of the current flowing through the antenna electrodes 4c and 4d tends to be higher than the level of the current flowing through the other antenna electrodes 4a and 4b. The threshold value TH2 is set so that the signal data relating to the current flowing through the antenna electrode exceeds a certain value and the signal data relating to the current flowing to the other antenna electrodes becomes smaller than the predetermined value. The threshold value TH2 is equal to the threshold value TH1.
Less than. Therefore, the signal data relating to the current flowing through the two adjacent antenna electrodes is larger than the threshold data TH2, and the signal data relating to the current flowing through the other antenna electrodes is smaller than the threshold data TH2. If so, the occupant would be determined to be a child.

Therefore, actual signal data relating to the current flowing through the plurality of antenna electrodes 4a to 4d, which is taken into the memory (storage means) of the control circuit 20, is stored in the control circuit 2 in advance.
0 is compared with threshold values TH1 and TH2 relating to the identification of the occupant stored in an external memory (storage means) of 0, for example, as shown in FIG. If the threshold value is larger than the threshold value TH2), it is determined that the occupant is an adult P. Thus, the airbag device 30 is set so that the airbag can be deployed by the transmission signal from the control circuit 20.
Further, as shown in FIG. 5, the actual signal data at two adjacent antenna electrodes is larger than the threshold value TH2,
If the actual signal data at the other antenna electrode is smaller than the threshold value TH2, the occupant is determined to be a child. As a result, the airbag device 30 is controlled by the control circuit 2
The transmission signal from 0 sets the airbag so that it cannot be deployed.

In the control circuit 20, the occupant determination is mainly described for discriminating between an adult and a child, but it can also be performed for a middle person between an adult and a child. in this case,
Signal data pattern related to the current flowing through the antenna electrode
(The level of the signal data corresponding to the head is high, the level of the other parts is low, but it is larger than the child's level and smaller than the adult's). By setting appropriate judgment conditions such as thresholds based on certain facts, and comparing actual data with the judgment conditions, it is possible to identify adults, middle persons and children.

According to this embodiment, a plurality of band-shaped antenna electrodes 4a to 4a are provided above the backrest 1b of the sheet 1.
Since the antenna electrodes 4a to 4d are arranged at substantially constant intervals in the width direction and extend vertically.
4d shows various parts of the occupant seated on the seat 1 (head,
A current flows according to the difference between the facing area between the antenna electrodes 4a to 4d, the distance between the antenna electrodes 4a to 4d, and the dielectric constant of each part. For this reason, in the case of an adult having a high sitting height and a wide shoulder width, the pattern of the current flowing through the antenna electrodes 4a to 4d becomes high, and in the case of a child having a low sitting height and a narrow shoulder width, the current level becomes high. The pattern is divided into an antenna electrode and an antenna electrode having a low current level. Therefore, it is possible to accurately determine whether or not the occupant is an adult, etc., based on the magnitude relationship between the signal data regarding these currents, and based on the occupant determination, the airbag device 3.
0 airbag can be reliably set to one of a deployable state and an undeployable state, and undesired deployment can be prevented.

The antenna electrodes 4a to 4d are arranged above the backrest 1b of the seat 1. If they extend to the lower part, the antenna electrodes 4a to 4d can be arranged even if the occupant's sitting height is small. Since the current corresponding to the body shape, sitting height, etc., flows through 4d, the sitting height of the occupant can be specified based on the magnitude and pattern of signal data relating to this current,
The identification of the occupant can be determined more finely.

Further, since the plurality of antenna electrodes 4a to 4d are arranged in the width direction on the backrest portion 1b of the sheet 1, if the occupant is displaced in the lateral direction of the sheet, the side of the displaced side is displaced. The current flowing through the antenna electrode of the first embodiment increases. Therefore, it is possible to easily detect how much the position is deviated from the current pattern flowing through the antenna electrode due to stagnation or the like, and to accurately cooperate with the airbag device.

It should be noted that the present invention is not limited to the above embodiment, and the number of antenna electrodes arranged on a sheet can be appropriately increased or decreased. Further, the electric field generating means is configured to generate an almost square-wave high-frequency low voltage with only the positive power supply by performing a switching operation based on a pulse signal from the control circuit, in addition to the oscillation circuit that generates the high-frequency low voltage. And its output frequency is 120KH
An appropriate frequency other than z can be set, and the voltage can be used outside the range of 5 to 12 V. Further, the amplitude control circuit can be omitted depending on the accuracy of the system power supply, the function expected of the system, and the like. In addition, if individual signal data relating to the current flowing through the antenna electrode is converted into a ratio with the respective sum data to perform various processing, individual signal data can be obtained depending on the thickness and body shape of the occupant. Even if the absolute value of the signal data fluctuates, it is not necessary to change the threshold value for various determinations of the occupant each time, and highly reliable determination can be expected. Further, it is also possible to arrange an antenna electrode at the end (sheet support portion) of the sheet so as to detect sleeping of the child and prevent the deployment of the side airbag.

[0031]

As described above, according to the present invention, a plurality of strip-shaped antenna electrodes are arranged at substantially constant intervals in the width direction and vertically in the backrest of the sheet. Therefore, the antenna electrode is designed according to the difference in the area, distance, and dielectric constant of each part (head, neck, shoulder, back, etc.) of the occupant seated on the sheet with the antenna electrode. Current flows. For this reason, in the case of an adult with a high sitting height, the pattern of the current flowing through the antenna electrode becomes high. In the case of a child with a low sitting height, an antenna electrode with a high current level and an antenna electrode with a low current level are formed. The pattern is divided into Therefore, it is possible to accurately determine whether or not the occupant is an adult based on the magnitude relationship of the signal data relating to these currents, and to deploy the airbag of the airbag device based on the occupant determination. It can be reliably set to one of the state and the state in which deployment is impossible, and it is possible to prevent undesired deployment.

Further, since the plurality of antenna electrodes are arranged in the width direction on the backrest portion of the seat as described above, the occupant's seating posture may fall down or shift in the lateral direction of the seat. In such a case, the current flowing to the antenna electrode on the side where the position is shifted or the like increases. Therefore, it is possible to easily detect in which direction and how much the occupant is displaced from the current pattern flowing through the antenna electrode, the magnitude of the current, and the like, and to accurately cooperate with the airbag device. .

In particular, if the antenna electrode disposed on the sheet is extended to the lower part of the backrest portion, even if the occupant's sitting height is small, the antenna electrode has a current corresponding to its body shape, sitting height, etc. Flows, it becomes possible to specify the occupant's sitting height based on the magnitude and pattern of the signal data relating to this current, and to determine the occupant's identification more finely.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a vehicle interior part of an occupant detection system according to the present invention, wherein FIG. 1 (a) is a side view showing an arrangement state of antenna electrodes on a sheet, and FIG. The front view of figure (a).

2 is a specific configuration diagram of the antenna electrode shown in FIG. 1, wherein FIG. 2 (a) is a plan view and FIG. 2 (b) is a cross-sectional view of FIG. 1 (a).

FIG. 3 is a circuit block diagram of an occupant detection system according to the present invention.

FIG. 4 is a current pattern when an adult is seated on a sheet.
5A is a signal data diagram based on the current flowing through each antenna electrode in a normal seated state, and FIG. 4B is a diagram illustrating the current flowing through each antenna electrode in a displaced seated state. FIG.

FIG. 5 is a current pattern when a child is seated on a sheet.
5A is a signal data diagram based on the current flowing through each antenna electrode in a normal seated state, and FIG. 4B is a diagram illustrating the current flowing through each antenna electrode in a displaced seated state. FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet 1a seating portion 1b backrest portion 4 (4a to 4d) antenna electrode 5 base member 6 (6a to 6d) lead wire 10 control unit 11 electric field generating means (oscillation circuit) 15 current detection circuit 16 AC -DC conversion circuit 17 Amplifier 18 (18a to 18d) Switching circuit 19a to 19d Connector (terminal) 20 Control circuit 22 Power supply circuit 30 Airbag device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Takashi Saito, Inventor, 1-44-2 Shiromi, Chuo-ku, Osaka City, Osaka Prefecture Inside of NEC Home Electronics Co., Ltd. (72) Masahiro Oto, Shinura, Kanagawa-ku, Yokohama, Kanagawa Prefecture 1-1-1 Shimamachi 25 Within NEC Robot Engineering Co., Ltd. (72) Inventor Tsutomu Fukui 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute, Inc. (72) Inventor Nobuhiro Koshiroda Saitama 1-4-1, Chuo, Wako-shi, Honda R & D Co., Ltd. (72) Inventor Takashi Ino 1-4-1, Chuo, Wako-shi, Saitama Pref., Honda R & D Co., Ltd. (72) Inventor, Kazumasa Isonaga Saitama 1-4-1 Chuo Wako-shi F-term in Honda R & D Co., Ltd. (Reference) 3B088 QA05 3D054 AA03 EE09 EE10 EE31 FF16 FF20

Claims (5)

[Claims] 1. A plurality of strip-shaped antenna electrodes arranged on a backrest of a sheet at substantially constant intervals in the width direction and so as to extend in a vertical direction, and for generating a weak electric field around the antenna electrodes. Electric field generating means, a current detecting circuit for selectively generating a weak electric field around a specific antenna electrode among a plurality of antenna electrodes, and detecting a current flowing based on the electric field, and a current detected from the current detecting circuit. A control circuit for determining whether or not the occupant is an adult based on the signal data. 2. A plurality of strip-shaped antenna electrodes arranged on a backrest of the sheet at substantially constant intervals in the width direction and so as to extend in the vertical direction, and for generating a weak electric field around the antenna electrodes. Electric field generating means, a current detecting circuit for selectively generating a weak electric field around a specific antenna electrode among a plurality of antenna electrodes, and detecting a current flowing based on the electric field, and a current detected from the current detecting circuit. A control circuit for determining whether or not the occupant is an adult based on the signal data; and an airbag device having a function of deploying the airbag based on the collision. Based data to the airbag device,
An occupant detection system, wherein an airbag of an airbag device is set to one of a deployable state and an undeployable state. 3. The control circuit according to claim 1, wherein the control circuit stores at least threshold data relating to the identification of the occupant, a means for receiving an output signal from the current detection circuit, and a signal data from the current detection circuit. 3. The occupant detection system according to claim 1, further comprising a determination unit configured to determine whether or not the occupant is an adult by comparing the data with threshold data. 4. The plurality of strip-shaped antenna electrodes,
The electric field generating means is selectively connected to a specific antenna electrode by a switching operation of a switching circuit.
Or the occupant detection system according to 2. 5. The occupant detection system according to claim 1, wherein the plurality of strip-shaped antenna electrodes extend and are arranged downward from an upper portion of a seat back portion.