JP2000075043A - Occupant detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an occupant detection system for appropriately detecting the seated state of an occupant and at the same time appropriately controlling an air bag device based on the detection result. SOLUTION: A weak electric field is selectively generated around a plurality of antenna electrodes 4 (4a-, 4n) being arranged separately at a rear part 1b of a seat 1, current flowing to the antenna electrodes is detected based on the weak electric field, the seated condition of an occupant P on the seat is detected based on the current, and at the same time data based on the detection result is transmitted to the air bag device, thus setting the air bag of the air bag device to either expandable or not expandable.

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 detection system according to the state of separation between an occupant and a dashboard in a passenger seat of an automobile equipped with an airbag device.
The present invention relates to an improvement in an occupant detection system capable of setting an airbag device to a predetermined operation mode.

[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.

Incidentally, recently, when an impact due to a collision or the like is applied to a vehicle equipped with an airbag device, the airbag device can be appropriately controlled in accordance with the occupant's seating posture on the seat. Is desired. For example, as shown by the dotted line in FIG. 7, when the occupant P falls asleep and the upper body is quite close to the dashboard DB,
In some cases, it is desirable not to deploy the airbag of the airbag device even if the vehicle collides.

When the side airbag device is mounted at the seat end or the door portion of the driver's seat and the passenger's seat, as shown by a dotted line in FIG. When the vehicle is very close to Dr, it may be desirable not to deploy the airbag of the side airbag device even if an impact is applied to the side of the vehicle.

However, when the occupant is in a seating posture as shown by a dotted line in FIG. 7 or FIG. 8, the load sensor and the capacitance detection sensor (electrode) disclosed in the above-mentioned prior arts use the occupant's posture. Even if the presence or absence of seating can be detected,
There is a problem that it is not possible to accurately detect even the sitting posture of a seated occupant.

Therefore, there is a need for an occupant detection system that can appropriately control the airbag device and the side airbag device even when the occupant is too close to the dash board or door in the event of a collision or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide an occupant detection system capable of accurately detecting the occupant's seating state on a seat and appropriately controlling the airbag device based on the detection result. It is in.

[0012]

SUMMARY OF THE INVENTION Accordingly, in order to achieve the above-mentioned object, the present invention provides a plurality of antenna electrodes which are arranged on a backrest of a sheet so as to be substantially symmetrical on the left and right sides, An electric field generating means for generating a weak electric field around the antenna electrode, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the plurality of antenna electrodes, and a switching operation of the switching circuit. A current detection circuit that generates a weak electric field around the selected antenna electrode and detects a current flowing from the electric field generation means to the antenna electrode based on the weak electric field, and a plurality of output signals output from the current detection circuit. And a control circuit for determining the occupant's seating state on the seat.

According to a second aspect of the present invention, there are provided a plurality of antenna electrodes spaced apart from each other so as to be substantially symmetrical on the backrest of the sheet, and a weak electric field is generated around the antenna electrodes. Electric field generating means, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among a plurality of antenna electrodes, and a weak electric field around the antenna electrode selected by the switching operation of the switching circuit. And a current detection circuit for detecting a current flowing from the electric field generating means to the antenna electrode based on the weak electric field, and a phase difference for detecting a phase difference between a transmission signal from the electric field generating means and an output signal to the antenna electrode. A detection circuit; and a control circuit for determining a seating state of the occupant on the seat based on a plurality of output signals output from the current detection circuit and the phase difference detection circuit. That.

According to a third aspect of the present invention, there are provided a plurality of antenna electrodes spaced apart from each other so as to be substantially symmetrical on the backrest of the sheet, and a weak electric field is generated around the antenna electrodes. Electric field generating means, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among a plurality of antenna electrodes, and a weak electric field around the antenna electrode selected by the switching operation of the switching circuit. And a current detection circuit for detecting a current flowing from the electric field generating means to the antenna electrode based on the weak electric field, and a phase difference for detecting a phase difference between a transmission signal from the electric field generating means and an output signal to the antenna electrode. A detection circuit, a control circuit for determining a seating state of the occupant on the seat based on a plurality of output signals output from the current detection circuit and the phase difference detection circuit, and an airbag based on the collision. An airbag device having a function of deploying the airbag, transmitting data based on the determination result of the control circuit to the airbag device, and deploying or not deploying the airbag of the airbag device. It is set in any one of the states.

Further, a fourth invention of the present invention comprises the electric field generating means, the current detection circuit, and the control circuit, and these circuits are housed in the same housing to constitute a control unit. According to a fifth aspect of the present invention, in the control circuit, in the control circuit, various kinds of seating patterns of the occupant stored in advance and transmission related to currents flowing from the electric field generating means to the respective antenna electrodes are provided. The occupant's seating state is determined by comparing the occupant's seating pattern calculated based on the signal data and extracting the corresponding seating pattern.

[0016]

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 the 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 the antenna electrodes. Is to detect the seating status of the user on the sheet.

An embodiment of an occupant detection system according to the present invention utilizing this principle will be described with reference to FIGS. FIGS. 1 and 2 show the arrangement of a passenger seat (or driver's seat) and antenna electrodes according to the present invention, and a seat 1 mainly includes a seating portion 1a and a backrest portion 1b. I have. The seat portion 1a includes, for example, a seat frame 3 fixed to a base 2 slidable back and forth,
A cushioning material arranged on the upper part of the sheet frame 3,
The backrest portion 1b includes, for example, a cushion material disposed on the front side of the sheet frame, and the cushion material is covered with the exterior material. In particular, a plurality of antenna electrodes 4 (4a to 4n) are arranged on the backrest portion 1b so as to be separated from each other inside the exterior member and to be substantially symmetrical on the left and right sides. 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 arranged such that square antenna electrodes 4a to 4n of the same size are spaced apart from one another on one surface of a base member 5 made of an insulating member. It is desirable to be comprised by doing, and it is arrange | positioned inside the exterior | packing material of the backrest part 1b. Lead wires 6 (6a to 6n) are independently led out from the respective antenna electrodes 4a to 4n, and connectors (or terminals) 19a to 1 of the control unit 10 described later.
9n.

A control unit 10 is disposed in the sheet frame 3 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. An 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
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 4n connected to the current detection circuit 15 and having a plurality of switching means 18a to 18n.
n switching circuits 18, connectors 19 a to 19 n connected to the switching means 18 a to 18 n of the switching circuit 18 and arranged in the housing of the control unit, an amplitude control circuit side (oscillation circuit side) of the current detection circuit 15, and A phase difference detection circuit connected to the switching circuit side (antenna electrode side) for detecting a phase difference between a transmission signal from the oscillation circuit and an output signal to the antenna electrode; and amplifying an output signal of the phase difference detection circuit. An amplifier 21, a control circuit 22 including a CPU, an external memory, and the like; a connector 23 arranged in the housing and connected to a battery power source (not shown);
Power supply circuit 24 connected between the control circuit 3 and the control circuit 22
It is composed of An airbag device 30 is connected to the control circuit 22 of the control unit 10. still,
Switching means 18a to 18n in switching circuit 18
Is selectively performed based on a signal from the control circuit 22.

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 22, and the variable amplitude signal for the variable amplitude section 13a is output from the control circuit 22.

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 the control circuit 22 via the AC-DC conversion circuit 16 and the amplifier 17. And the current detection circuit 1
5, the output side of the resistor 15a is connected to the connectors 19a to 19n via the switching circuit 18.

Further, as shown in FIG. 4A, for example, the phase difference detection circuit 20 separates a transmission signal from the oscillation circuit 11 and an output signal to the antenna electrodes 4 (4a to 4n) from a sine wave into a square. A waveform shaping circuit 20a for shaping the waveform into waves,
20a, a first flip-flop circuit 20b1, a second flip-flop circuit 20b2, and an integrating circuit 20c
And the waveform shaping circuit 20a
Is configured, for example, as shown in FIG.
The high frequency low voltage output from the oscillation circuit 11 is, for example, +
If the waveform is generated by a switching operation or the like from a single 5V power supply and the waveform is a square wave, the waveform shaping circuit 20a
Can be omitted.

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 22. The control circuit 22 determines whether 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 connector. As a result, a weak electric field is generated around the antenna electrode 4. At this time, the switching circuit 18 is controlled to open and close by a signal from the control circuit 22. First, only the switching means 18a is closed, then only the switching means 18b is closed, and so on. The switching control is performed so that only the switching means is closed and the other switching means are opened at the same time. Therefore, the specific switching means (18a-18)
When n) is closed, the transmission signal whose voltage amplitude is fixed is sent to the current detection circuit 15, specific switching means (18a to 18n), and specific connectors (19a to 19).
n) to the specific antenna electrodes (4a to 4n), as a result, a weak electric field is generated around the specific antenna electrodes (4a to 4n), and the occupant sitting on the seat 1 Different values of current flow according to the seating posture of P.
This current is detected by the current detection circuit 15 and AC-
The signal is converted into a direct current by the DC conversion circuit 16, amplified by the amplifier 17, and input to the control circuit 22 one after another.

On the other hand, the signal (voltage) at both ends of the current detection circuit 15, that is, the transmission signal from the oscillation circuit 11 on the amplitude control circuit side and the output signal to the antenna electrode 4 on the switching circuit side (antenna electrode side) are different in phase difference. When input to the detection circuit 20, the sine wave signal is shaped into a square wave by the waveform shaping circuit 20a as shown in FIG. 5A, and output to the first and second flip-flop circuits 20b1 and 20b2. You. The rising edge (arrow shown) of the square wave output on the transmission side is the terminal CK of the first flip-flop circuit 20b1.
, And the terminal Q bar outputs a high (High) output. On the other hand, the receiving side also detects the rising edge (arrow in the drawing) of the square wave output at the terminal B of the second flip-flop circuit 20b2 as shown in FIG. A low output is output as one shot. When this output signal is input to the terminal RES of the first flip-flop circuit 20b1, the output of the terminal Q bar of the first flip-flop circuit 20b1 becomes
As shown in FIG. 3C, the data is inverted to row. This output becomes a phase amount (phase difference), which is converted into a voltage by passing through an integration circuit 20c.
2 is input. The operation of detecting the phase amount is sequentially performed in response to the operation of detecting the transmission current to each antenna electrode by the current detection circuit 15.

The control circuit 22 preliminarily relates to various seating patterns of the occupant P seated on the seat 1 and the phase difference between the transmission signal to the current detection circuit 15 and the output signal to the antenna electrode. A threshold (threshold data) is stored. Specifically, as for the seating pattern, as shown in FIG. 6 (a), for example, the level of the transmission current to the hatched antenna electrode is high, and the level of the unshaded antenna electrode is Is significantly lower,
The occupant P seated at G1 is an adult occupant, and the seating pattern is set as a normal seating pattern. With this pattern, the antenna electrodes 4b, 4c, 4
If the current level of f, 4 g is slightly lower than that of the normal seating pattern, the occupant seated on the seat 1 is an adult occupant, and the seating pattern of the upper body is a dashboard.
This is set as a seating pattern having a forward leaning posture toward the DB. Further, as shown in FIG. 3B, when the hatched antenna electrode group is displaced to the left, the occupant P seated on the seat 1 is an adult occupant. The seating pattern is set as a sitting pattern whose upper body is approaching the door Dr. Further, in other patterns, the occupant is set as not being an adult.

On the other hand, regarding the phase difference, an average phase difference detected by the phase difference detection circuit 20 when an occupant is seated on the sheet 1 and an average position detected by the presence of a person other than a person. An arbitrary value between the differences is set as a threshold value for determining that a person is seated. It should be noted that an upper limit and a lower limit can be set for the threshold value depending on the state of the sheet (for example, water wetness), and when phase difference data exists within the range, a person sits down. Is determined to be. Therefore, the control circuit 22 compares the threshold data regarding the seating pattern and the phase difference stored in advance with the seating pattern and the phase difference data based on the input current. As a result, whether or not the occupant seated on the seat 1 is an adult and the occupant's seating pattern (for example, seating posture) are accurately determined. Note that the current detection circuit 15
The detection current increases when the separation distance between the occupant P and the antenna electrode 4 decreases, and decreases when the separation distance increases. Further, the phase difference increases when the occupant P is seated on the seat 1 and decreases when the luggage is placed or not seated, and there is a clear level difference between the two. Is what you do.

Accordingly, the signal data taken into the control circuit 22 is compared with a previously stored seating pattern, and a corresponding pattern is extracted. If the extracted seating pattern is, for example, the pattern shown in FIG. 6A, it is determined that the occupant is an adult and has a normal seating posture, and the airbag device 30 is controlled. The transmission signal from the circuit 22 sets the airbag to be deployable. Conversely, when the extracted pattern is a pattern as shown by the dotted line in FIG. 1A or as shown in FIG. 6B, the occupant is too close to the dashboard DB or the door Dr, It is determined that the seating posture is not normal, and the airbag device 30 is set in such a manner that the airbag cannot be deployed by the transmission signal from the control circuit 22. It should be noted that even when the extracted pattern is not an adult seated pattern, the airbag device 30 may be used.
Is set so that the airbag cannot be deployed by the transmission signal from the control circuit 22.

According to this embodiment, the backrest 1b of the sheet 1 is provided with a plurality of antenna electrodes 4 (4
a to 4n) are spaced apart from each other, and a weak electric field is generated in order by applying a high-frequency low voltage to each antenna electrode, so that the antenna electrodes 4 (4a to 4n)
In n), a current flows according to the seating pattern (seating posture) of the occupant P seated on the seat 1. Therefore, the seating pattern of the adult occupant P can be easily detected from these current patterns.

In addition, the phase difference between the transmission signal from the oscillation circuit and the output signal to the antenna electrode 4 on the oscillation circuit side and the antenna electrode side of the current detection circuit 15 differs depending on the object existing on the sheet 1. In particular, when the object is a person, the object has a phase difference of a level difference that can be identified as compared with other objects. Accordingly, by detecting the phase difference by the phase difference detection circuit 20, the determination of the signal data relating to the seating pattern based on the detected current and the determination of the signal data relating to the seating pattern facilitates the occupant seat 1. The presence or absence of a seat can be reliably detected.

In particular, the airbag of the airbag device 30 is set to one of a deployable state and an undeployable state based on the determination whether the occupant P is an adult. For example, if it is determined that the occupant P is not an adult, the airbag of the airbag device 30 is set to a state where it cannot be deployed. Therefore, even if the vehicle collides, the airbag is not deployed, so that the deployment operation of the airbag device can be appropriately controlled depending on whether or not the occupant is an adult.

The sheet 1 has a plurality of antenna electrodes 4.
(4a to 4n) are arranged, and based on the current pattern based on the magnitude of the current transmitted to each antenna electrode, the occupant is seated on the seat 1 as shown in FIG. It can be easily detected even if you are seated. Therefore, when the side airbag device is mounted, another vehicle is placed on the side of the automobile while the occupant P in the driver's seat or the passenger's seat is approaching the door Dr more than necessary as shown in FIG. Even if a collision occurs, even if the occupant is an adult, the airbag of the side airbag device may not be deployed.

In addition, when the seating posture of the occupant P is as shown by the dotted line in FIG. 1 (a), the current flowing through the antenna electrode disposed above the backrest 1b is reduced, but is disposed below. Since the current flowing through the antenna electrode does not decrease so much, it can be easily detected based on the pattern whether or not the upper body of the occupant is approaching the dashboard DB. Therefore, the deployment operation of the airbag device can be appropriately controlled as described above.

In particular, in the control unit 10, in addition to using a single power supply by the power supply circuit 24 as a system power supply,
If the oscillating circuit 11 is configured to generate a substantially square-wave high-frequency low voltage using only the positive power supply, the power supply circuit 24,
The circuit configuration of the unit as well as the oscillation circuit 11 can be simplified, and the cost of the system can be significantly reduced.

Since the voltage amplitude of the transmission signal transmitted to the antenna electrodes 4 (4a to 4n) is controlled by the amplitude control circuit 12 to be substantially constant, the current detection circuit 15
It is easy to compare and judge the data related to the current detected by the above with the seating pattern data stored in the control circuit 22, thereby enabling highly reliable and accurate detection.

Furthermore, since the control circuit 22 previously stores various seating patterns of the occupant on the seat 1 based on the currents transmitted to the plurality of antenna electrodes 4, the current detection circuit 15 By comparing the current pattern with the current pattern based on the current flowing through each antenna electrode 4 and extracting the corresponding pattern, the occupant's seating pattern can be accurately determined.

It should be noted that the present invention is not limited to the above-described embodiment, but the shape of the antenna electrodes arranged on the sheet may be rectangular, circular, elliptical, or polygonal except square. It can be formed, and the number of arrangement can be appropriately increased or decreased from 16 pieces. Also, the electric field generating means can be configured to generate a substantially square wave high-frequency low voltage by switching the positive power supply using a clock signal from a control circuit in addition to the oscillation circuit,
Its output frequency also depends on the conditions such as the vehicle interior.
It can be set to a value other than 0 KHz, and its voltage can be 5
It can be used outside the range of ~ 12V. Further, the amplitude control circuit and the phase difference detection circuit can be omitted depending on the accuracy of the system power supply, the functions expected of the system, and the like.

[0038]

As described above, according to the present invention, a plurality of antenna electrodes are arranged at a distance from each other on the back portion of the sheet, and high-frequency and low-voltage Since a weak electric field is generated by the application,
A current flows through each antenna electrode according to the seating pattern of the occupant sitting on the sheet. Therefore, the seating status, such as whether or not the occupant is an adult and whether or not the occupant is in a normal seating posture, can be accurately detected by these current patterns.

In particular, the airbag of the airbag device is set to one of a deployable state and a non-deployable state according to the determination based on the occupant's seating status. For example, if it is determined that the occupant is not an adult or the seating posture is not normal such as leaning toward the door or the like, the airbag of the airbag device is set to a non-deployable state. Therefore,
Even if the vehicle collides, the airbag is not deployed, so that the occupant can more appropriately control the airbag.

Further, since the control circuit previously stores various seating patterns of the occupant on the sheet based on the currents transmitted to the plurality of antenna electrodes, it is detected by the current detection circuit. By comparing the current pattern with the current pattern based on the current flowing through each antenna electrode and extracting the corresponding pattern, the seating pattern of the occupant can be accurately determined.

[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.

4A is a circuit block diagram of a specific example of the phase difference detection circuit shown in FIG. 3, and FIG. 4B is a circuit block diagram of a waveform shaping circuit.

5A and 5B are diagrams for explaining the operation of the phase difference detection circuit shown in FIG. 4, wherein FIG. 5A is a waveform diagram of a transmission signal and an output signal of a first flip-flop circuit, and FIG. FIG. 4B is a waveform diagram of the output signal and the output signal of the second flip-flop circuit, and FIG. 4C is a diagram showing a detection state of a phase amount from the output signals of the first and second flip-flop circuits.

FIGS. 6A and 6B are diagrams for explaining a seating pattern of an occupant on a sheet, wherein FIG. 6A shows a state where the occupant is seated at a normal position, and FIG. The figure which shows the state shifted to the side.

FIG. 7 is a schematic side view showing a state in which an occupant is seated on a passenger seat of a conventional automobile.

FIG. 8 is a schematic front view showing a state where an occupant is seated on a driver's seat or a passenger seat of a conventional automobile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sheet 1a Seated part 1b Backrest part 4 (4a, 4b ... 4n) Antenna electrode 5 Base member 6 (6a, 6b ... 6n) Lead wire 10 Control unit 11 Electric field generating means (Oscillation) Circuit) 12 Amplitude control circuit 13 Amplitude variable circuit 14 Amplitude detection circuit 15 Current detection circuit 16 AC-DC conversion circuit 17, 21 Amplifier 18 (18a, 18b ... 18n) Switching circuit 19a, 19b ... 19n Connector (terminal) ) 20 phase difference detection circuit 22 control circuit 24 power supply circuit 30 airbag device DB dash board Dr door

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazunori Jinno 1-44-2 Shiromi, Chuo-ku, Osaka City, Osaka Prefecture Within NEC Home Electronics Co., Ltd. (72) Inventor Masahiro Ohto Shinura, Kanagawa-ku, Yokohama-shi, Kanagawa 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 City, Honda R & D Co., Ltd. (72) Inventor Takashi Ino 1-4-1, Chuo, Wako City, Saitama Prefecture, Ltd.Honda R & D Co., Ltd. (72) Inventor Makoto Nagai, Saitama 1-4-1 Chuo, Wako-shi F-term in Honda R & D Co., Ltd. (Reference) 3D054 AA03 AA06 AA14 AA17 EE09 EE10 EE1 1 EE19 EE20 EE31 FF16

Claims (5)

[Claims] 1. A plurality of antenna electrodes arranged on a backrest of a sheet so as to be substantially symmetrical left and right, an electric field generating means for generating a weak electric field around the antenna electrodes, and a plurality of electric field generating means. A switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the antenna electrodes; and a weak electric field is generated around the antenna electrode selected by the switching operation of the switching circuit. A current detection circuit for detecting a current flowing from the electric field generating means to the antenna electrode, and a control circuit for judging an occupant's seating state on the sheet based on a plurality of output signals output from the current detection circuit. An occupant detection system characterized in that: 2. A plurality of antenna electrodes which are spaced apart from each other so as to be substantially symmetrical on the backrest of the sheet, an electric field generating means for generating a weak electric field around the antenna electrodes, and a plurality of electric field generating means. A switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the antenna electrodes; and a weak electric field is generated around the antenna electrode selected by the switching operation of the switching circuit. A current detection circuit for detecting a current flowing from the electric field generating means to the antenna electrode; a phase difference detecting circuit for detecting a phase difference between a transmission signal from the electric field generating means and an output signal to the antenna electrode; An occupant detection system comprising: a control circuit configured to determine an occupant's seating state on a seat based on a plurality of output signals output from the phase difference detection circuit. 3. A plurality of antenna electrodes disposed on the backrest of the sheet so as to be substantially symmetrical left and right, an electric field generating means for generating a weak electric field around the antenna electrodes, and a plurality of electric field generating means. A switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the antenna electrodes; and a weak electric field is generated around the antenna electrode selected by the switching operation of the switching circuit. A current detection circuit for detecting a current flowing from the electric field generating means to the antenna electrode; a phase difference detecting circuit for detecting a phase difference between a transmission signal from the electric field generating means and an output signal to the antenna electrode; It has a control circuit for judging the occupant's seating state on the seat based on a plurality of output signals output from the phase difference detection circuit, and a function for deploying the airbag based on a collision. An airbag device that transmits data based on the determination result of the control circuit to the airbag device, so that the airbag of the airbag device can be in one of a deployable state and an undeployable state. An occupant detection system characterized by being set. 4. A control unit comprising the electric field generating means, a current detection circuit, and a control circuit, and these circuits are housed in the same housing to constitute a control unit, and the control unit is arranged in a sheet portion. The occupant detection system according to any one of claims 1 to 3. 5. The occupant calculated based on various pre-stored seating patterns of the occupant and transmission signal data relating to currents flowing from the electric field generating means to the respective antenna electrodes. Comparison with the seating pattern of
The occupant detection system according to any one of claims 1 to 3, wherein the occupant's seating status is determined by extracting a corresponding seating pattern.