JP3322297B2 - Occupant detection system and occupant detection method - Google Patents

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 an occupant detection method, and more particularly, to an airbag of an airbag device that can be deployed according to the occupant's seating state in a passenger seat of an automobile equipped with the airbag device. The present invention relates to an improvement in an occupant detection system and an occupant detection method that can be set to a state or an undeployable state.

[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 an automobile collision.
It has become indispensable to the safety of automobiles, and is recently being installed not only in the driver's seat but also in the passenger seat.

As shown in FIG. 11, for example, this airbag apparatus has a self-service sensor SS1 and a squib SQ.
1, a squib circuit on the driver's seat side comprising a series circuit of semiconductor switching elements SW1 such as a field effect transistor, and a semiconductor switching element SW such as a safing sensor SS2, a squib SQ2 and a field effect transistor.
2, a squib circuit on the passenger seat side, an electronic acceleration sensor (collision detection sensor) GS, and an electronic acceleration sensor G
The control circuit CC has a function of determining the presence or absence of a collision based on the output signal of S and supplying a signal to the gates of the semiconductor switching elements SW1 and SW2.

According to this airbag device, when an automobile collides for some reason, the switching contacts of the safety sensors SS1 and SS2 are closed in response to a relatively small acceleration, and the safety sensors SS1 and SS2 are closed. The squib circuit on the passenger seat side becomes operable. When the control circuit CC determines that the vehicle has definitely collided based on the signal from the electronic acceleration sensor GS, a signal is supplied to the gates of the semiconductor switching elements SW1 and SW2, and the switching elements SW1 and SW2 are turned on. Becomes ON state. As a result, current flows through each squib circuit,
Due to the heat generated by the squibs SQ1 and SQ2, the airbags on the driver's seat side and the passenger's seat side are deployed, and the occupant is protected from the impact due to the collision.

By the way, according to this airbag device,
For example, as shown in FIG. 12 (a), when an adult P is seated on the seat 1, the above-described occupant protection effect can be expected at the time of a collision. However, as shown in FIG. (B), the passenger seat sheet - Child and fixed on sheet 1 sheet - if bets 1A infant SP is sitting backward (R ear F acing I nfant S eat: less, (Referred to as RFIS), since the deployment of the airbag may adversely affect the infant SP, it is desirable that the airbag should not be deployed even if the vehicle collides. Also, FIG.
As shown in (1), when the infant SP is sitting forward on the child seat 1A fixed on the seat 1 in the passenger seat ( F
orward F acing C hild S eat: below, when the air bag is a concern that covers the face of the child SP by deployment of the air bag is to be referred to as FFCS), RFIS
As in the case of the above, it is desirable that the airbag should not be deployed even if the vehicle collides.

Therefore, in order to cope with such a problem, an airbag device as shown in FIG. 13 has been proposed. In this airbag device, a sensor SD for detecting whether or not an occupant is seated in a passenger seat is installed, and a control circuit CC determines a seating state of the occupant in the passenger seat based on a detection signal of the sensor SD. When an automobile collides, the airbag is set to one of a deployable state and an undeployable state. In particular, the sensor SD uses a weight sensor that measures the weight based on the amount of distortion of a piezoelectric element or the like. It has been proposed to make a determination as to whether or not such is the case.

According to the former method, it is possible to roughly determine whether the occupant is an adult P or a child SP by one weight sensor disposed on the sheet, and the airbag is deployed based on the result. Although it can be set to either a possible state or a non-deployable state to avoid an unexpected event at the time of a car collision, the weight varies greatly between individuals, and it is possible that children and adults may be heavier than adults Accordingly, there is a problem that not only the accuracy is lacking but also it is not possible to determine whether the state is the RFIS or the FFCS.

According to the latter method, the occupant is seated, the occupant is determined to be an adult P or a child SP,
Although it is possible to determine whether the child is in the RFIS or FFCS state fairly accurately, it is necessary to perform image processing on image data taken by a camera and make comparison judgments with various patterns. In addition, there is a problem that the processing apparatus becomes complicated and expensive.

[0009]

Accordingly, the present applicant has
Previously, an occupant detection system as shown in FIGS. 14 to 18 has been proposed. This occupant detection system basically has a weak electric field (Ele) generated between two electrodes arranged on a sheet.
ctric field). First, as shown in FIG. 14A, when the oscillation circuit 10 for generating a high-frequency low voltage is connected to the electrode E1 and the electrode E2 is connected to the ground, the electrodes E1 and E2 are connected based on the potential difference between the electrodes. An electric field is generated, and the displacement current I
d flows. In this state, when the object OB is present in the electric field, the electric field is disturbed and the displacement current Id1 different from the displacement current Id flows to the electrode E2 as shown in FIG. Become. Most objects OB are electrically represented by conductance and capacitance, and are coupled to ground via capacitance.

Therefore, the displacement current flowing on the side of the electrode E2 changes depending on whether the object OB is on the vehicle seat or not, and by utilizing this phenomenon, It is possible to detect the occupant's seating status on the sheet. In particular, by increasing the number of electrodes, it becomes possible to obtain a lot of information about an object including an occupant on the sheet, and it is possible to more accurately detect the occupant's seating state on the sheet.

A specific occupant detection system utilizing this principle will be described with reference to FIGS. still,
The same parts as those of the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 15 shows a sheet according to the prior art, in which a plurality of electrodes are arranged on the front side of the sheet 1 in the passenger seat. Specifically, for example, rectangular electrodes E1 and E2 are arranged in the seating portion 1a, and electrodes E3 and E4 having substantially the same shape are arranged in the backrest portion 1b. These electrodes are formed of a conductive cloth in consideration of the occupant's comfort, but weaving a thread-like metal on the sheet cloth surface, applying conductive paint to the cloth surface, It can also be configured by arranging plates. These electrodes E1 to E4 are shown in FIG. 16 (FIG. 17).
Is connected to and incorporated in the circuit shown in FIG.

In FIG. 16, the occupant detection system has a frequency of about 100 KHz and a voltage of 10 to 12 V, for example.
An oscillation circuit 10 for generating a high-frequency low voltage of about the same level, a load current detection circuit 11, a transmission / reception switching circuit 12, a current / voltage conversion circuit 13 having an amplification function, a band-pass function and an AC-DC conversion function ( A detection circuit (demodulation circuit) 14 having an unnecessary noise removing function), an amplification circuit 15, an offset conversion circuit 16, and a control circuit 17 such as an MPU.
And an airbag device 18. FIG.
Is a more specific example of the circuit of FIG. 16. The amplifier circuit 15 includes, for example, a first amplifier circuit 15 </ b> A and a second amplifier circuit 15 </ b> B having a gain G of 1 × and 100 ×. An analog selection circuit 19 for selecting output signals of the second amplifier circuits 15A and 15B is provided.
The analog selection circuit 19 is controlled by the control circuit 17.

In this system, the load current detecting circuit 11 comprises, for example, an impedance element such as a resistor 11a connected in series to the circuit, and an amplifier 11b for amplifying the terminal voltage of the resistor 11a. 10
The current (load current) supplied to the specific electrode selected from is detected. The transmission / reception switching circuit 12 includes, for example, switching means Aa to Ad for connecting a selected one of the electrodes E1 to E4 (referred to as a transmission electrode) to the output side of the oscillation circuit 10; The other electrodes (referred to as receiving electrodes) are connected to the current / voltage conversion circuit 13 by switching means Ba to Bd. Switching of each switching means is controlled by the control circuit 17. It is desirable that the transmission / reception switching circuit 12 be constituted by a multiplexer circuit. The current / voltage conversion circuit 13 includes, for example, an impedance element such as a resistor 13a for converting a displacement current flowing on the receiving electrode side into a voltage, and an amplifier 13 for amplifying the converted voltage.
b and are provided corresponding to the respective electrodes E1 to E4. The analog selection circuit 19 includes, for example, four switching means 19a which are simultaneously selected and connected to the output side of the second amplification circuit 15B and four switching means 19 which are simultaneously selected and connected to the output side of the first amplification circuit 15A. And a switching means 19b.

The system configured as described above operates as follows. First, based on a signal from the control circuit 17, only the switching means Aa of the transmission / reception switching circuit 12 is connected to the output side of the oscillation circuit 10, and the switching means Bb to Bd are connected to the current / voltage conversion circuit 13. ,
A high-frequency low voltage is applied from the oscillation circuit 10 to the transmission electrode E1, and a displacement current flows through the reception electrodes E2 to E4. This current is converted into a voltage by the resistor 13a, amplified by the amplifier 13b, and output to the detection circuit 14. On the other hand, the load current flowing through the transmission electrode E1 is detected by the load current detection circuit 11 and output to the detection circuit 14 as data R (1, 1) described later. In the detection circuit 14, for example, a signal of about 100 KHz is band-passed, and unnecessary noise components are removed.
A, 15B. The first and second amplifier circuits 1
The output signals of 5A and 15B are appropriately selected by the operation of the offset conversion circuit 16 and the analog selection circuit 19, and output to the control circuit 17. For example, if the output signal from the detection circuit 14 can be measured in the full range, the four switching means 19b of the analog selection circuit 19
Only one is simultaneously selected and connected to the output side of the first amplifier circuit 15A. When it is difficult to measure a subtle change in a full range due to a small output signal, only the four switching means 19a of the analog selection circuit 19 are simultaneously selected and connected to the output side of the second amplification circuit 15B. . Then, in the control circuit 17, the output signals from the first and second amplifier circuits 15A and 15B are A / D converted and then stored in the memory.

Next, based on a signal from the control circuit 17, the switching means Aa of the transmission / reception switching circuit 12 is opened, only the switching means Ab is connected to the output side of the oscillation circuit 10, and the switching means Ba, Bc, Bd is the current
When connected to or changed to the voltage conversion circuit 13, a high-frequency low voltage is applied from the oscillation circuit 10 to the transmission electrode E2,
Displacement currents flow in 1, E3, and E4. This current is converted into a voltage by the resistor 13a, amplified by the amplifier 13b, and output to the detection circuit 14. The load current flowing through the transmission electrode E2 is detected by the load current detection circuit 11 and output to the detection circuit 14 as data R (2, 2) described later. The data is processed in the same manner as described above and stored in the control device 17 as data. Next, the switching means Ac
Only to the output side of the oscillation circuit 10 and the switching means Ba, Bb, Bd to the current / voltage conversion circuit 13.
When changed, a high-frequency low voltage is applied from the oscillation circuit 10 to the transmission electrode E3, and a displacement current flows through the reception electrodes E1, E2, and E4. The load current flowing through the transmission electrode E3 is detected by the load current detection circuit 11, and the data R to be described later is used.
It is output to the detection circuit 14 as (3,3). further,
When only the switching means Ad is connected to the output side of the oscillation circuit 10 and the switching means Ba, Bb, Bc is connected or changed to the current / voltage conversion circuit 13, a high-frequency low voltage is applied from the oscillation circuit 10 to the transmission electrode E4, Receiving electrode E1,
A displacement current flows through E2 and E3. These displacement currents are converted into voltages by the resistor 13a, amplified by the amplifier 13b, and output to the detection circuit 14. The transmission electrode E
4 is detected by a load current detecting circuit 11 and is detected as data R (4, 4) to be described later.
4 is output. The processing is performed in the same manner as described above, and the control device 17
Is stored as data.

The control circuit 17 calculates the seating pattern by arithmetically processing these data. Various types of seating patterns are stored in the control circuit 17 in advance, and the seating patterns calculated by data based on various combinations of transmission electrodes and reception electrodes at the electrodes E1 to E4 are stored in advance. The stored seating pattern is compared with the stored seating pattern, and the corresponding seating pattern is extracted and determined. In the control circuit 17, for example, various seating patterns described below are provided.
Is the target of the judgment. Specifically, an empty seat pattern where no occupant is seated on the seat, an FFCS pattern where the child is seated in the child seat in the FFCS state, and a child seat where the child is in the RFIS state. R sitting at
The FIS pattern is a person pattern in which an adult is seated on a sheet. Each of the electrodes E1 to E4 is appropriately selected, and various combinations of transmission electrodes and reception electrodes are used.
The data represented by the general formula R (i, j) is obtained. In the general formula R (i, j), i = j represents transmission data, and i ≠
j indicates reception data, i indicates a transmission electrode, and j indicates a reception electrode. In the control circuit 17, arithmetic processing is performed using, for example, 16 pieces of data for each pattern, and the characteristics of the seated pattern are extracted.

When the seating pattern is detected and specified in the control circuit 17, a signal based on the detected pattern is transmitted to the airbag device 18. For example, the seating pattern is empty, FFC
In the case of S, RFIS, a signal is sent to the airbag device 18 to set the airbag so that the airbag does not expand even if the vehicle collides. In other patterns, the airbag is expanded. Is transmitted. These signals are input to the control circuit CC of the airbag device 18, and in the case of the former pattern, they are set so as not to supply a gate signal to the semiconductor switching element SW2 on the passenger seat side in the event of a collision. A gate signal is supplied to the semiconductor switching element SW1 on the driver's seat side. In the latter case, it is set so that a gate signal is supplied to the semiconductor switching elements SW1 and SW2. In some cases, the seating pattern is FFCS
In this case, a signal for setting the airbag to be deployed may be transmitted.

According to this prior art, a plurality of electrodes E1 to E4 are arranged on the front surface side of the sheet 1, and between one selected transmitting electrode and a receiving electrode other than the transmitting electrode. Since the weak electric field is generated by the application of the high frequency and low voltage, a displacement current related to the occupant's seating pattern on the sheet 1 flows on the receiving electrode side. Therefore, by determining the characteristic pattern of the displacement current, the occupant's seating pattern can be accurately detected. For this reason, the airbag of the airbag device 18 can be set to any of a deployable state and an undeployable state according to the seating pattern of the occupant.

In addition, since a plurality of electrodes are arranged on the sheet 1 at a distance from each other, the number of combinations of transmitting electrodes and receiving electrodes can be increased, and the number of obtained data can be increased. -It is possible to more accurately determine the pattern in which the occupant sits on the vehicle.

The control circuit of the system includes, for example, RF
Since the current pattern characterized by the current flowing through each electrode based on the seating pattern of IS, FFCS, Person, Empty is stored in advance as the seating pattern, the transmitting electrode and the receiving electrode are appropriately set. By comparing received signal data obtained by combining the above with various kinds of seating patterns stored in advance and extracting the corresponding stored seating pattern, the actual seating pattern can be accurately detected.
An excellent effect such as the ability to detect the noise can be obtained.

However, according to the occupant detection system according to the prior art, the excellent effect can be expected as described above, but since the number of received data obtained from the plurality of electrodes is large, the seating in the control circuit is not possible. Pattern determination processing becomes complicated, and the cost of the system tends to increase.

On the other hand, for example, as shown in FIG.
Sensor S for detecting whether or not an occupant is seated in the passenger seat
If a weight sensor is used as D, the cost of the system can be effectively reduced, but the weight sensor detects only the weight of the object located in the passenger seat, and RFIS,
There is a problem that it is not possible to detect even the seating pattern of the FFCS.

Therefore, an object of the present invention is to provide an occupant detection system and an occupant detection method capable of reliably detecting various occupant states such as occupants and reducing the cost of the system.

[0024]

SUMMARY OF THE INVENTION Accordingly, in order to achieve the above-mentioned object, the present invention has a structure in which antenna electrodes are arranged on both sides of a cushioning base member at a seating portion of a sheet. A plurality of weight sensors are spaced apart from each other, and a displacement current flowing based on a weak electric field generated between the antenna electrodes of these weight sensors is detected, whereby an occupant or the like sits on a sheet. The second invention of the present invention is characterized in that the plurality of weight sensors are spaced apart from each other at a front part and a rear part of a seat occupant.

According to a third aspect of the present invention, antenna electrodes are arranged on both sides of a seat and a base member having cushioning properties, which is spaced apart from a seating portion of the seat. An oscillation circuit for generating a weak electric field between the antenna electrodes of the plurality of weight sensors, and the displacement current flowing based on the weak electric field generated between the antenna electrodes of the plurality of weight sensors. And a control circuit for detecting a seating state of an occupant or the like on a sheet based on an output signal of the current / voltage conversion circuit.

According to a fourth aspect of the present invention, antenna electrodes are arranged on both surfaces of a sheet and a cushioning base member which is spaced apart from a seating portion of the sheet. An oscillation circuit for generating a weak electric field between the antenna electrodes of the plurality of weight sensors, and the displacement current flowing based on the weak electric field generated between the antenna electrodes of the plurality of weight sensors. A current / voltage conversion circuit for converting the voltage into a voltage, a control circuit for detecting a seating state of an occupant or the like on a seat based on an output signal of the current / voltage conversion circuit, and an airbag deployed based on the collision. An airbag device having a function, transmitting data based on the detection result of the control circuit to the airbag device, and allowing the airbag of the airbag device to be in a deployable state or in an undeployable state. Characterized in that it set towards.

According to a fifth aspect of the present invention, the oscillation circuit is configured to generate a high-frequency low voltage, and the first antenna electrode of the weight sensor is connected to a transmission electrode to which a high-frequency low voltage is applied. In addition, the second antenna electrode is used as a receiving electrode, and a weak electric field is generated between the transmitting electrode and the receiving electrode by applying a high-frequency low voltage. According to a seventh aspect of the present invention, the base member of the weight sensor comprises a member capable of changing a distance between antenna electrodes according to the weight of an occupant or the like sitting on a seat. The circuit corresponds to threshold data corresponding to a stored pattern of the occupant or the like stored in advance, and a seated pattern of the occupant or the like based on displacement currents detected by a plurality of weight sensors. Compare with received signal data It allows and controls to detect the seating state, such as the passenger.

According to an eighth aspect of the present invention, a plurality of weight sensors having antenna electrodes on both sides of a base member having cushioning properties are arranged at a seat occupant portion at a distance from each other. A displacement current flowing based on a weak electric field generated between the antenna electrodes of these weight sensors is detected, a seating pattern of an occupant or the like is detected based on the displacement current, and based on the detection result. Data is transmitted to the airbag device, and the airbag of the airbag device is set to one of a deployable state and an undeployable state.

[0029]

Next, the basic principle of the present invention will be described with reference to FIG. The occupant detection system and the occupant detection method according to the present invention basically utilize the disturbance of the weak electric field generated between the antenna electrodes as in the above-described prior art. First, as shown in FIG. 1A, a pair of electrodes E1 and E2 are opposed to each other while being separated from each other.
When an oscillating circuit 10 for generating a high-frequency low voltage is connected to the electrodes E1 and E2, an electric field is generated at the electrodes E1 and E2 based on the potential difference between the electrodes. , A displacement current Id related to the dielectric constant of an object existing in the device flows. In this state, when the object OB is placed on the electrode E1 as shown in FIG. 2B, for example, the electrode E1 (the object existing between the electrodes E1 and E2) is deformed in accordance with the weight of the object OB, and the distance between the electrodes is reduced. Is partially narrowed, and the electric field is disturbed. For this, it is on the side of the electrode E2 through a different displacement current Id ₁ and the displacement current Id shown in FIG. 6 (a), the displacement current Id ₁ varies depending on the distance between the substantially electrodes. Therefore, by utilizing this phenomenon, it is possible to detect the occupant's seating status on the seat.

Next, an occupant detection system according to the present invention utilizing this principle will be described with reference to FIGS. The same parts as those in the prior art shown in FIGS. 14 to 18 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG.
Indicates a sheet according to the present invention.
Is mainly composed of a seating portion 1a and a backrest portion 1b. The sheet 1B includes, for example, a seat frame 3 fixed to a base 2 which can be slid forward and backward, a cushion member 4 disposed on the upper portion of the sheet frame 3, and a cushion member 4. The first and second weight sensors 5 and 5A are arranged apart from each other along the surface, and the exterior material 6 is arranged to cover the first and second weight sensors 5 and 5A. ing. In the following description, for convenience,
The side of the first weight sensor 5 may be referred to as a channel 1 and the side of the second weight sensor 5A may be referred to as a channel 2.

In particular, the first and second weight sensors 5 and 5A have substantially the same structure, and are arranged separately from each other on the surface of the cushion member 4 corresponding to the front and rear portions of the seat 1a. I have. These weight sensors 5 and 5A are deformed when pressurized, such as sponge or rubber, and return to the original shape when the pressing force is removed. 5a, the first and second antenna electrodes E1 and E2 arranged on both surfaces. It is recommended that the thickness of these weight sensors 5 and 5A be set to, for example, 10 mm or less, preferably 8 mm or less in consideration of the occupant's sitting comfort.

In the first and second weight sensors 5 and 5A, the first and second antenna electrodes E1 and E2 are formed of conductive cloth in consideration of the comfort of the occupant.
It can also be constructed by weaving a thread-like metal on the sheet cloth surface or by applying a conductive paint on the cloth surface. The first and second antenna electrodes E1 and E2 are arranged on both surfaces of the base member 5a so as to face each other. The fixing of the antenna electrodes E1, E2 and the base member 5a is performed by bonding, sewing, or the like by heating an adhesive, a thermoplastic or thermosetting resin. For example, fixing with an adhesive is recommended, but adhesion by heating of a thermoplastic or thermosetting resin is also effective. That is, the first and second antenna electrodes E1 and E2 are impregnated or coated with a thermoplastic or thermosetting resin, and the respective antenna electrodes are connected to the base member 5.
The antenna electrodes E1 and E2 and the base member 5a are adhered and fixed by heating and pressing in a state where the antenna electrodes E1 and E2 are arranged at the predetermined position a.

Although these weight sensors 5 and 5A are interposed between the cushion member 4 and the exterior member 6, it is recommended that they be fixed to at least one of them. For this fixing, the same method as that for fixing the antenna electrodes E1 and E2 to the base member 5a can be employed, as well as by means of hooks, buttons, hooks or the like, or by means of a magic tape.

Further, the first and second weight sensors 5, 5
A, the first and second antenna electrodes E1,
A harness (not shown) is derived from E2, and FIG.
Are connected to the control unit shown in FIG. By arranging this control unit in a sheet 1B, for example, in a sheet frame portion, the length of harness derived from each antenna electrode can be shortened or a part of the antenna electrode can be extended. By doing so, the harness and the antenna electrode can be integrated.

The occupant detection system including the above-described control unit is configured, for example, as shown in FIG. This occupant detection system generates first and second weight sensors 5 and 5A disposed in a seat 1a of a seat 1B and a high-frequency low voltage having a frequency of about 100 KHz and a voltage of about 6 to 12 V, for example. Oscillation circuit 10 and load current detection circuit 11
A current-voltage conversion circuit 13 having an amplification function, a filter circuit 14 having a band-pass function, and an amplification circuit 15
And a control circuit 17 such as an MPU, and an airbag device 18
It is composed of The above-mentioned control unit is constituted by a circuit excluding the airbag device 18, for example.

In this system, the weight sensors 5, 5
An oscillation circuit 10 is connected via a load current detection circuit 11 so that each first antenna electrode in A functions as a transmission electrode. This load current detection circuit 1
Reference numeral 1 denotes, for example, an impedance element such as a resistor 11a connected in series to a circuit, and an amplifier 11b for amplifying a terminal voltage of the resistor 11a. Also, weight sensor 5, 5A
Each of the second antenna electrodes E2 functions as a receiving electrode and is connected to the current / voltage conversion circuit 13. The current / voltage conversion circuit 13 is, for example, an impedance converter for converting a displacement current flowing on the second antenna electrode side into a voltage.
It is composed of a dance element, for example, a resistor 13a, and an amplifier 13b for amplifying the converted voltage. Each output signal is taken into the control circuit 17 via the filter circuit 14 and the amplifier circuit 15.

The system configured as described above operates as follows. First, when a high-frequency low voltage is applied from the oscillation circuit 10 to the first antenna electrodes E1 and E1 of the first and second weight sensors 5 and 5A via the load current detection circuit 11, each of the first and second weight sensors 5 and 5A is turned on. A weak electric field is generated between the antenna electrode E1 and the second antenna electrode E2.
Then, a displacement current corresponding to the state of sitting on the sheet 1B flows to the side of each of the second antenna electrodes E2 and E2. For example, as shown in FIG. 4A, when the child seat 1A is arranged on the sheet 1B in the FFCS state, the load applied to the second weight sensor 5A is equal to the first weight sensor 5A. And a larger displacement current flows on the second weight sensor 5A side than on the first weight sensor 5 side. Also, as shown in FIG.
In the case of the arrangement in the state of S, contrary to the case of the FFCS, a larger displacement current flows on the side of the first weight sensor 5 than on the side of the second weight sensor 5A. Further, when the adult occupant P is seated, the displacement current detected by the first and second weight sensors 5 and 5A in FIG. A larger displacement current flows.

These currents are input to the current / voltage conversion circuit 13, converted into voltages by the resistors 13a, amplified by the amplifier 13b, and output to the filter circuit 14. In this filter circuit 14, for example, 100 KH
A signal of about z is band-passed, unnecessary noise components are removed, and output to the amplifier circuit 15. Then, the amplifier circuit 15 amplifies the input signal to a desired level and outputs the signal to the control circuit 17. In the control circuit 17, after the output signal from the amplifier circuit 15 is A / D converted, the output signal is stored in a memory as received signal data. The load current flowing through the first antenna electrodes E1 and E1 of each channel is detected by the load current detection circuit 11 and taken into the control circuit 17.

On the other hand, the control circuit 17 previously stores the total sum of the average displacement current flowing through each channel when the occupant P is seated and the average flowing through each channel when the child seat 1A is disposed. An arbitrary value between the total displacement current and the total sum is stored as a threshold value (threshold data). Therefore, when the output signal of the amplifier circuit 15 relating to the displacement current detected on the respective second antenna electrode side is actually taken into the control circuit 17 as received signal data, it is stored in the control circuit 17 in advance. By comparing (calculating) the threshold value data and the actual received signal data, the seating pattern in the sheet 1B is detected.

Therefore, if the received signal data is larger than the threshold data, it is determined that the occupant P is seated.
Conversely, if the received signal data is smaller than the threshold data, it is determined that child sheet 1A is arranged on sheet 1B, and the received signal data of each channel is further determined.
According to the comparison of the received signals, when the received signal data is ch1> ch2, the received signal data is arranged in the RFIS state,
If the data is ch1 <ch2, it is determined that the data is arranged in the FFCS state. Based on the results of these decisions,
A signal is transmitted from the control circuit 17 to the airbag device 18. The airbag device 18 is set in accordance with a transmission signal from the control circuit 17 so that the airbag can be deployed or cannot be deployed. That is, the transmission signal from the control circuit 17 is input to the control circuit CC of the airbag device 18, and, for example, when the child seat 1A is arranged in the RFIS state, the semiconductor switching on the passenger seat side at the time of collision of the car is performed. The gate switch is set so as not to supply the gate signal to the element SW2, and in patterns other than RFIS, the gate signal is set so as to be supplied to the semiconductor switching elements SW1 and SW2. A gate signal is supplied to the semiconductor switching element SW1 on the driver's seat side.

Next, the processing flow of the occupant detection system will be described.
Will be described with reference to FIGS. First, as shown in FIG. 5, the ignition switch is turned on to start. Initialization is performed in step S1, and the process proceeds to step S2. In step S2, an initial diagnosis relating to the communication system between the control circuit 17 and the airbag device 18 is performed. In step S3, it is determined whether or not the engine has started. If it is determined that the engine has started, the process proceeds to step S4. If it is determined that it has not started, the process returns. In step S4, the displacement current flowing to the second antenna electrode side based on the weak electric field generated between the first antenna electrode (transmission electrode) E1 and the second antenna electrode (reception electrode) E2 of each channel is calculated. The associated signal data is received. Then, in step S5, the seating status of the occupant or the like to the sheet 1B is determined (occupant determination) based on the acquired data. Further, step S6
In SRS communication is performed with the airbag device (SRS) 18 based on the determination result of step S5. When step S6 ends, the process returns to step S4, and the processes from step S4 to step S6 are repeatedly performed.
Step S3 can be omitted.

The initial diagnosis in FIG. 5 is performed, for example, as shown in FIG. First, in step SA1, the fixed data
From the control circuit 17 to the control circuit C of the airbag device 18.
Send to C. In step SA2, the airbag device 18
Receive the transmission data from. Then, Step SA3
Then, it is determined whether or not the fixed data transmitted from the control circuit 17 to the airbag device 18 and the received data from the airbag device 18 match. If it is determined that the respective data match, the processing flow is continued. If it is determined that the respective data do not match, it is determined that there is an abnormality in the communication system, a fail-safe process is performed, and, for example, a warning lamp is turned on. In this initial diagnosis, fixed data is transmitted from the airbag device 18 to the control circuit 17, and the transmitted data from the control circuit 17 is determined by the control circuit CC of the airbag device 18 regarding the coincidence. You may do so.

The occupant determination in FIG. 5 is performed, for example, as shown in FIG. First, in step SB1, is the received signal data related to the sum of the displacement currents flowing to the second antenna electrodes in the channels 1 and 2 larger than the threshold data stored in the control circuit 17 in advance? It is determined whether or not. If it is determined that the received signal data is larger than the threshold data, the process proceeds to step SB2, where ON data for deploying the airbag of the airbag device 18 is set, and the processing flow is continued. Is done. Step S
If it is determined in B1 that the received signal data is smaller than the threshold data, the flow advances to step SB3 to determine whether the received signal data of channel 1 is larger than the received signal data of channel 2. Will be determined. If it is determined that the received signal data of channel 1 is larger than the received signal data of channel 2, the process proceeds to step SB4, in which OFF data for preventing the airbag of the airbag device 18 from being deployed is output. It is set, and the processing flow is continued. On the other hand, if it is determined that the received signal data of channel 1 is smaller than the received signal data of channel 2, the process proceeds to step SB5, where ON data for deploying the airbag of the airbag device 18 is set. And the processing flow is continued, and S
It continues to the RS data communication flow.

The SRS data communication in FIG. 5 is performed, for example, as shown in FIG. First, in step SC1, an ON state is set from the occupant detection unit side (the control circuit 17) to the airbag apparatus side (the control circuit CC) so that the airbag of the airbag apparatus 18 can be deployed or cannot be deployed. -Data or OFF data and check data are transmitted. In step SC2, OK data for ON data or OFF data from the airbag device side is output.
Data or NG data and check data are received, and the flow advances to step SC3. In step SD3, the ON / OFF data transmitted from the occupant detection unit to the airbag device is transmitted.
It is determined whether the data and check data are returned from the airbag device to the occupant detection unit again in a normal state. If it is determined to be normal (there is no abnormality in the communication system)
The processing flow is continued. If it is determined that the communication system is abnormal, the process proceeds to step SC4, where it is determined whether the fail-safe timer has reached zero. The abnormality detection of the communication system is set to, for example, three times. Therefore, when it is determined that the fail-safe timer has reached zero, a fail-safe process is performed, for example, a warning light is turned on. If it is determined that the fail-safe timer has not reached zero, the process proceeds to step SC5, where the fail-safe timer is set.
The timer is counted, and the processing flow is continued.

On the other hand, in step SD1, the airbag device side (control circuit CC) is connected to the occupant detection unit side (control circuit 1).
From (7), ON data or OFF data and check data for bringing the airbag of the airbag device 18 into a deployable state or an undeployable state are received. In step SD2, the received data is checked to determine whether the received data has been normally received. In any case, the process proceeds to step SD3, where O
K data or NG data and check data are transmitted to the occupant detection unit. If it is determined in step SD2 that there is no abnormality in the communication system, the OK data in step SD3 is output.
After the data transmission step, the process proceeds to step SD4. In step SD4, the data on the airbag device side is updated based on the OK data. As a result, the airbag is updated and set to one of a deployable state and an undeployable state. If it is determined in step SD2 that there is something wrong with the communication system, the flow advances to step SD5 via the NG data transmission step in step SD3. In this step SD5, it is determined whether or not the fail-safe timer has become zero. Incidentally, the abnormality detection of this communication system is, for example, 3
Set to times. Therefore, when it is determined that the fail-safe timer has reached zero, a fail-safe process is performed, for example, a warning light is turned on. If it is determined that the fail-safe timer has not become zero, the process proceeds to step SD6, where the fail-safe timer is counted, and the processing flow is continued.

According to this embodiment, the first and second weight sensors 5 and 5A are arranged in the seat 1a of the seat 1B so as to be separated from each other in the front and rear directions. Since a weak electric field is generated by the application of a high-frequency low voltage, a sheet 1B is provided on the second antenna electrode side.
A displacement current flows according to the occupant P and the child seat 1A seating status (arrangement status). Therefore, it can be easily detected from the magnitude of the displacement current whether the occupant P is seated or whether the child seat 1A is placed in the FFCS or RFIS state.

In particular, the airbag of the airbag device 18 is set to one of a deployable state and a non-deployable state based on a seating pattern of an occupant or the like on the seat 1B. For example, child sheet 1A is RF
If it is determined that the airbag is located in the IS state, the airbag of the airbag device 18 is set to a state where it cannot be deployed. Therefore, even if the vehicle collides, the airbag is not deployed, so that the child SP can be prevented from being secondary damaged by the airbag.

Further, the first and second weight sensors 5 and 5A are constituted by arranging the first and second antenna electrodes on both sides of the base member so as to face each other. The spout member is made of a member having a cushioning property, such as sponge or rubber, whose interval between the antenna electrodes can be changed according to the weight of the occupant or the like sitting on the seat 1B. The level change of the displacement current flowing to the electrode side can be accurately received. Therefore, these weight sensors 5,
It is possible to accurately detect the seating status of the occupant or the like on the seat 1B from the current pattern based on 5A.

Furthermore, since the control circuit 17 stores in advance the threshold data relating to the displacement current corresponding to the occupant's seating status, the second antenna of each of the weight sensors 5 and 5A is provided. By comparing the received signal data and the threshold data with respect to the displacement current from the electrode side and comparing the received signal data between the channels, the seating status of the seat can be any of RFIS, FFCS and occupant P. Can be accurately determined.

In particular, in the seat 1a of the seat 1B, two weight sensors are merely arranged at a distance from each other in the front-back direction.
The number of data taken into the memory becomes small. Therefore, the processing in the control circuit 17 can be simplified, and the cost can be reduced.

FIG. 9 shows another embodiment of the weight sensor according to the present invention.
5A is fixed to one surface of the pad member 7 made of an insulating member at a predetermined interval. For this fixation,
For example, the bonding is performed by an appropriate means such as bonding of an adhesive, a thermoplastic or thermosetting resin by heating, and sewing. In this assembled structure, the pad member 7 is provided between the cushion member 4 and the exterior member 6 of the sheet 1B shown in FIG.
It is interposed so as to be on the side. The pad member 7 is preferably made of a cloth material, but any suitable member such as a cushion material may be used as long as the pad member 7 has an insulating property.

According to this embodiment, since the assembly structure including the first and second weight sensors 5 and 5A can be incorporated into the sheet only by arranging it on the cushion material 4, For example, work on an automatic assembly line can be performed smoothly.

FIG. 10 shows another embodiment of the occupant detection system according to the present invention, which is basically the same as the embodiment shown in FIG. The difference is that the second antenna electrodes E2 and E2 in the first and second weight sensors 5 and 5A are different.
That is, the channel switching circuit 12A is connected between the current / voltage conversion circuit 13 and the current / voltage conversion circuit 13, and the current / voltage conversion circuit 13, the filter circuit 14, and the amplifier circuit 15 are each configured by a single circuit. This channel switching circuit 1
2A is constituted by first and second switching means 12a and 12b, and switching control of these switching means is performed by a signal from the control circuit 17.

This system operates as follows. When a high frequency low voltage is applied from the oscillation circuit 10 to the first and second weight sensors 5 and 5A, only the first switching means 12a of the channel switching circuit 12A is closed by a signal from the control circuit 17, A displacement current flowing to the second antenna electrode side according to the seating state is supplied to the current / voltage conversion circuit 13 via the first switching means 12a.
Is input to the control circuit 17 via the filter circuit 14 and the amplifier circuit 15 as received signal data. Next, the first switching means 12a is opened by a signal from the control circuit 17, and the second switching means 12b is opened.
When only the second switching means 12 is closed, the displacement current flowing to the second antenna electrode side according to the seating state is changed.
The signal b is input to the current / voltage conversion circuit 13 via the filter b, and is received as received signal data by the control circuit 17 via the filter circuit 14 and the amplifier circuit 15. These data are compared with threshold data stored in the control circuit 17 in advance to detect the seating state and to allow or deploy the airbag of the airbag device 18 based on the detection result. Set to be impossible.

According to this embodiment, since the received signal of each channel is switched by the first and second switching means 12a and 12b, the current / voltage conversion circuit 1
3. The filter circuit 14 and the amplifier circuit 15 can be constituted by a single circuit. Therefore, the system configuration can be simplified,
The cost can be reduced.

The present invention is not limited to the above embodiment. For example, the weight sensor may have a rectangular shape in a planar state, or may have a polygonal shape excluding a circle, an ellipse, and a square. Yes, the shape of the antenna electrode is changed accordingly. The number of the weight sensors may be increased to three or more in addition to two, and the weight sensor may be arranged on the outer surface of the exterior material or incorporated in the exterior material itself. Further, the output signal of the load current detection circuit is taken into the control circuit, and the level fluctuation of the transmission current can be used for correcting the received signal data relating to the displacement current, or the load current detection circuit can be omitted. . The output frequency of the oscillating circuit can be set to a value other than 100 KHz in accordance with the condition of the vehicle interior. Further, the airbag device may use a mechanical sensor in addition to the electronic acceleration sensor.

[0057]

As described above, according to the present invention, a plurality of weight sensors are arranged in the seat occupant so as to be separated from each other back and forth. Since a weak electric field is generated by the application of the voltage, a displacement current flows on the second antenna electrode side according to the occupant on the seat and the seating state (arrangement state) of the child seat. Therefore, depending on the magnitude of the displacement current, the occupant may be seated or the child seat may be FFCS or RF.
It can be easily detected in which state the IS is located.

In particular, the airbag of the airbag device is set to one of a deployable state and an undeployable state based on a seating pattern of a passenger or the like on the seat. For example, if it is determined that the child seat is arranged in the RFIS state, the airbag of the airbag device is set to a state where it cannot be deployed. Therefore, even if the vehicle collides, the airbag is not deployed, so that the child can be prevented from being secondarily damaged by the airbag.

The weight sensor is constructed such that the first and second antenna electrodes are arranged on both sides of the base member so as to face each other. In particular, the base member is seated on a sheet. Since the distance between the antenna electrodes is changed according to the weight of the occupant or the like, the distance between the antenna electrodes can be changed. It can receive with high accuracy.
Therefore, the current pattern by these weight sensors
It is possible to accurately detect the occupant's seating status.

Furthermore, since the control circuit stores in advance the threshold data relating to the displacement current corresponding to the occupant's seating condition, the weight sensor receives the data from the second antenna electrode side. By comparing the received signal data and the threshold data relating to the displacement current and comparing the received signal data between the channels, the seating status of the seat can be determined by RFI.
S, FFCS, or an occupant can be accurately determined.

In particular, if two weight sensors are arranged in front and rear of the seat at a distance from each other, the number of data taken into the control circuit is smaller than in the prior art. The processing in the circuit can be simplified, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining a basic operation of an occupant detection system according to the present invention, wherein FIG. 1 (a) is a view showing a state in which a pressing force is not applied to an antenna electrode, and FIG.
FIG. 3 is a diagram showing a state in which a pressing force is applied to an antenna electrode.

FIG. 2 is a view showing a sheet of the occupant detection system according to the present invention, wherein FIG. 2 (a) is a sectional view of a main part, and FIG. 2 (b) is an enlarged view of the weight sensor shown in FIG. Side view.

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

FIG. 4 is a diagram for explaining a method of detecting an arrangement pattern of a child sheet, and FIG.
FIG. 2B is a side view of the apparatus in the state of RFIS.

FIG. 5 is a flowchart for performing occupant detection according to the occupant detection method according to the present invention.

FIG. 6 is a flowchart of an initial diagnosis shown in FIG. 5;

FIG. 7 is a flowchart for occupant determination shown in FIG. 5;

FIG. 8 is a flowchart of the SRS communication shown in FIG.

FIG. 9 is a side view showing a fixing structure of the weight sensor of the occupant detection system according to the present invention.

FIG. 10 is a circuit block diagram of another embodiment of the occupant detection system according to the present invention.

FIG. 11 is a circuit block diagram of an airbag device according to a conventional example.

12A and 12B are diagrams showing various seating patterns, in which FIG. 12A shows a state where an adult occupant is seated on a sheet, and FIG. 12B shows a state of RFIS. FIG.
FIG. 3 is a diagram showing a state of FFCS.

FIG. 13 is a circuit block diagram of an improved airbag device according to a conventional example.

14A and 14B are diagrams for explaining a basic operation of the occupant detection system according to the prior art which is a premise of the present invention, wherein FIG. 14A is a diagram showing an electric field distribution between electrodes, and FIG. FIG. 4 is a diagram showing an electric field distribution when an object exists between electrodes.

FIG. 15 is a perspective view of a sheet of the occupant detection system according to the prior art.

FIG. 16 is a circuit block diagram of an occupant detection system according to the prior art.

FIG. 17 is a specific circuit block diagram of FIG. 16;

18 is a detailed circuit block diagram of the airbag device shown in FIG.

[Explanation of symbols]

 Reference Signs List 1A Child sheet 1B Sheet 1a Seated portion 1b Backrest portion 2 Base 3 Sheet frame 4 Cushion material 5,5A First and second weight sensors 6 Exterior material 7 Pad member 10 Oscillator circuit 11 Load Current detection circuit 12A channel switching circuit 13 Current / voltage conversion circuit 14 Filter circuit 15 Amplification circuit 17 Control circuit 18 Airbag device E1, E2 Antenna electrode SS1, SS2 Safety sensor SQ1, SQ2 Squib SW1, SW2 Semiconductor switching element CC control Circuit GS Electronic acceleration sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-139233 (JP, A) JP-A-5-291924 (JP, A) JP-A-5-291925 (JP, A) 281748 (JP, A) JP-A-11-281749 (JP, A) JP-A-11-271462 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60R 21/32 G01V 3 / 08

Claims (8)

(57) [Claims] 1. A plurality of weight sensors each having antenna electrodes disposed on both sides of a base member having cushioning properties are arranged at a seating portion of a sheet at a distance from each other. By detecting the displacement current flowing based on the weak electric field generated between the antenna electrodes,
An occupant detection system that detects the occupant's seating status. 2. The occupant detection system according to claim 1, wherein the plurality of weight sensors are arranged separately at a front portion and a rear portion of a seat occupant. 3. A plurality of weight sensors comprising antennas arranged on both sides of a seat, a cushioning base member spaced apart from a seating portion of the sheet, and a plurality of weights. An oscillation circuit for generating a weak electric field between the antenna electrodes of the sensor, and a current / voltage that detects the displacement current flowing based on the weak electric field generated between the antenna electrodes of the multiple weight sensors and converts it into a voltage An occupant detection system, comprising: a conversion circuit; and a control circuit that detects a seating state of an occupant or the like on a sheet based on an output signal of the current / voltage conversion circuit. 4. A sheet, a plurality of weight sensors having antenna electrodes disposed on both sides of a cushioning base member spaced apart from a seating portion of the sheet, and a plurality of weights. An oscillation circuit for generating a weak electric field between the antenna electrodes of the sensor, and a current / voltage that detects the displacement current flowing based on the weak electric field generated between the antenna electrodes of the multiple weight sensors and converts it into a voltage A conversion circuit, a control circuit for detecting a seating state of an occupant or the like on a sheet based on an output signal of the current / voltage conversion circuit, and an airbag device having a function of deploying the airbag based on a collision. The data based on the detection result of the control circuit is transmitted to the airbag device, and the airbag of the airbag device is set to one of a deployable state and an undeployable state. The occupant detection system. 5. The oscillation circuit is configured to generate a high-frequency low voltage, wherein the first antenna electrode of the weight sensor is a transmission electrode to which a high-frequency low voltage is applied, and
The occupant according to claim 3 or 4, wherein the second antenna electrode is a receiving electrode, and a weak electric field is generated between the transmitting electrode and the receiving electrode by applying a high-frequency low voltage. Detection system. 6. The base member in the weight sensor,
5. The occupant detection system according to claim 1, wherein the distance between the antenna electrodes can be changed according to the weight of the occupant sitting on the seat. 7. The control circuit according to claim 1, wherein the control circuit is configured to store threshold data corresponding to a seating pattern of the occupant or the like stored in advance and a displacement current detected by a plurality of weight sensors. 5. The occupant detection system according to claim 3, wherein control is performed so as to detect an occupant's seating state by comparing received signal data corresponding to the seating pattern. 8. A plurality of weight sensors each having antenna electrodes disposed on both sides of a cushioning base member at a seating portion of a seat, and the weight sensors are spaced apart from each other. A displacement current flowing based on a weak electric field generated between the electrodes is detected, a seating pattern of an occupant or the like is detected based on the displacement current, and data based on the detection result is transmitted to the airbag device. An occupant detection method, wherein the airbag of the airbag device is set to one of a deployable state and an undeployable state.