JP3413479B2 - Occupant detection system - 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 more particularly to a state in which an airbag of an airbag device can be inflated or undeployed depending on the occupant's seating condition in the passenger seat of a vehicle equipped with the airbag device. The present invention relates to an improvement of an occupant detection system that can be set in a possible state.

[0002]

2. Description of the Related Art Generally, an airbag device is a device for alleviating an impact on an occupant in a vehicle collision.
It has become indispensable for the safety of automobiles, and it is recently installed not only in the driver's seat but also in the passenger seat.

This airbag device is provided with a safing sensor SS1 and a squib SQ as shown in FIG.
1, a squib circuit on the driver's seat side consisting of a series circuit of a semiconductor switching element SW1 such as a field effect transistor, a safing sensor SS2, a squib SQ2, and a semiconductor switching element SW such as a field effect transistor
2 squib circuit on the passenger side, electronic acceleration sensor (collision detection sensor) GS, and 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 air bag device, when a car collides for some reason, the safing sensors SS1 and SS2 are closed by the switch contacts thereof reacting to a relatively small acceleration. The squib circuit on the passenger side becomes operable. Then, when the control circuit CC determines that the vehicle has surely collided on the basis of 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. It turns on. This results in current flowing through each squib circuit,
Due to the heat generation of 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, in this air bag system, the air bag is inflated by the collision of the vehicle regardless of whether or not the occupant is seated in the seat.
For example, when an adult passenger is seated in the passenger seat, the above-described passenger protection effect can be expected in a collision, but when the passenger is a child, the sitting height is lower than that of an adult. Since the head position is low, there is concern that the deployment of airbags may affect children. Therefore, if the occupant is a child, it may be desirable not to deploy the airbag even if the vehicle collides.

[0006]

Therefore, conventionally, in order to deal with such a problem, an airbag device as shown in, for example, FIG. 17 has been proposed. This airbag device is provided with a sensor SD for detecting whether or not a passenger is seated in the passenger seat, and the control circuit CC determines the seating status of the passenger in the passenger seat based on the detection signal of the sensor SD. When an automobile collides, the airbag is set to either a deployable state or an undeployable state. In particular, a weight sensor is used as the sensor SD, and whether the child is an adult or a child is determined based on the weight of the occupant measured by the weight sensor.
It has been proposed that an occupant seated in a seat is photographed with a camera and image processing is performed to determine whether the passenger is an adult or a child.

According to the former method, it is possible to roughly judge whether the occupant is an adult or a child, and based on this result, the airbag is set to either the inflatable state or the inflatable state. Although it is possible to avoid an unforeseen situation at the time of collision of a car, there is a problem in that the weight is largely different among individuals, and even if a child is heavier than an adult, accuracy is insufficient.

According to the latter method, the occupant's seating condition and whether the occupant is an adult or a child can be judged quite accurately, but various types of patterns are obtained by image-processing the image data captured by the camera. Therefore, there is a problem in that the processing apparatus becomes complicated and expensive because it is necessary to make a comparative judgment with the processing unit.

Therefore, an object of the present invention is to provide an occupant detection system capable of appropriately detecting the seating condition of an occupant in a seat and the like, and capable of appropriately controlling the airbag device based on the detection result. Especially.

[0010]

Therefore, in order to achieve the above-mentioned object, the present invention provides an electric field generating means for generating a weak electric field around a plurality of antenna electrodes spaced apart from each other in a sheet. And a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode of the plurality of antenna electrodes, and an electric field is generated around the specific antenna electrode selected by the switching circuit. An information detection circuit that detects information related to the current flowing through a specific antenna electrode based on the signal, and a signal output from the information detection circuit is taken in, and based on this signal data, the seating status of the occupant in the seat, etc. And a control circuit that determines whether or not the control circuit is included in the same housing to form a control unit, and the control unit is incorporated in a sheet.

A second aspect of the present invention is to specify an electric field generating means for generating a weak electric field around a plurality of antenna electrodes that are spaced apart from each other in a sheet, and a specific one of the plurality of antenna electrodes. A switching circuit for selectively switching and connecting the electric field generating means to the antenna electrode of, and an electric field is generated around the specific antenna electrode selected by the switching circuit, and a current flowing in the specific antenna electrode is generated based on this electric field. An information detection circuit for detecting related information and a signal output from the information detection circuit are fetched, and based on this signal data, a series of data is output.
A control circuit that determines the occupant's seating status in the passenger compartment and an airbag device that is set to either an inflatable state or an uninflatable state based on the determination result of the control circuit in the event of a collision. Among the above-mentioned components, at least an electric field generating means, a switching circuit, an information detection circuit, and a control circuit are included, and these are housed in the same housing to form a control unit. It is characterized by being incorporated into

Further, a third invention of the present invention is characterized in that the control unit is arranged at a frame portion of a seating portion or a backrest portion of a seat or in the vicinity thereof, and a fourth invention is characterized in that A fifth aspect of the present invention is characterized in that the control unit is incorporated in a sheet portion which is as close as possible to the antenna electrode. The fifth invention electrically connects the plurality of antenna electrodes to the control unit by a lead wire, and It is characterized in that the lead wire is wired so as not to be exposed from the seat on the seating side of the occupant.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the basic principle of the present invention will be described with reference to FIG. The occupant detection system according to the present invention basically utilizes the disturbance of the weak electric field generated in the antenna electrodes arranged in the seat. First, as shown in FIG. 7A, by applying a high frequency low voltage from the oscillation circuit OSC to the antenna electrode E1, a weak electric field is generated around the antenna electrode E1. A current I flows. In this state, as shown in FIG.
When the object OB is present near the antenna electrode E1, the electric field is disturbed and a current I ₁ different from the current I flows on the antenna electrode E1 side.

Therefore, the antenna electrode E is used depending on whether the object OB is on the seat of the automobile or not.
A change occurs in the current flowing to the side of No. 1, and by utilizing this phenomenon, the seating condition of the occupant in the seat can be detected. In particular, by increasing the number of antenna electrodes, it becomes possible to obtain a lot of information about objects including the occupant on the seat, and it is possible to more accurately detect the seating condition of the occupant on the seat. it can. The current flowing to the antenna electrode E1 increases when the object OB is on the sheet, and the antenna electrode E when the object OB is not on the sheet.
The current flowing to the 1 side decreases.

Next, an embodiment of an occupant detection system according to the present invention using this principle will be described with reference to FIGS. The same parts as those of the conventional example shown in FIGS. 16 to 17 are designated by the same reference numerals, and detailed description thereof will be omitted. 2 to 4 show the arrangement of the seat and the antenna electrode of the passenger seat (driver's seat) according to the present invention, and the seat 1 is mainly composed of a seat portion 1a and a backrest portion 1b. . The seating portion 1a includes, for example, a seat frame 3 fixed to a base 2 that is slidable forward and backward, a cushion material arranged above the seat frame 3, and an exterior material that covers the cushion material. The backrest part 1b
Is formed by, for example, disposing a cushion material on the front side of the sheet frame and covering the cushion material with an exterior material. In particular, the seating portion 1a has a plurality of antenna electrodes 4 (4a to 4) formed in substantially the same shape (for example, a rectangular shape).
d) are symmetrically arranged apart from each other. In addition, the antenna electrode 4 can be arranged not only inside the exterior material but also outside the exterior material, or can be provided on the exterior material itself. Also, see
A control unit 10, which will be described later, is incorporated in the seat 1 and is disposed, for example, in the seat frame 3 or in the vicinity thereof.

As shown in FIG. 3, for example, the antenna electrode 4 is basically composed of at least a base member 5 made of an insulating material such as non-woven fabric and one surface of the base member 5. It is composed of antenna electrode portions 4a to 4d having conductivity and spaced apart and symmetrically, and is arranged inside the exterior material of the seating portion 1a. In particular, although the antenna electrode portions 4a to 4d are made of, for example, conductive cloth, thread-like metal wires or conductive fibers are woven into the base member 5 or the seat of the seating portion 1a. Cloth side
It can be regarded as a cloth member and woven into the cloth member, a conductive paint is applied to the cloth surface, or a metal plate having a small thickness and flexibility. The antenna electrode portions 4a to 4d and the base member 5 are fixed to each other by heating an adhesive, a thermoplastic or thermosetting resin, sewn, joined by hooks, buttons, hooks, or joined by a magic tape. The method by adhesion is recommended. The antenna electrode portions 4a to 4d of the antenna electrode 4 of the illustrated example are configured to have, for example, rectangular shapes of substantially the same size. Further, hereinafter, for convenience of description, since the antenna electrode portions 4a to 4d have substantially the same function as the antenna electrode 4, they may be confused.

The antenna electrode 4 described above is shown in FIG.
It is configured as shown in (a) and (b). That is, the lead wires 6 (6a to 6d) such as shield wires are connected to a part of the antenna electrode portions 4a to 4d, the connection terminal 7 and the lug terminal 7A.
Electrically connected independently via a lead wire 6
A connector 9 is connected to the lead-out ends of (6a to 6d), and is connected to connectors (or terminals) 19a to 19d of a control unit 10 described later. In particular, the connection terminal 7 is configured to exhibit electrical connectivity by sandwiching the antenna electrode portion with a terminal component member made of a metal member, and for example, crimping tacks, hooks made of brass or the like can be used. .

In the above-mentioned antenna electrode 4, the antenna electrode portions 4a to 4d and the lead wires 6 (6a to 6) are provided.
Since the connection structure with d) is almost the same, the connection example between the antenna electrode portion 4a and the lead wire 6a will be specifically described as a representative example. The connection terminal 7 includes an antenna electrode portion 4a and a base.
The lug terminal 7A is attached by caulking and fixing it so as to penetrate through a preformed hole in the member 5, and the lug terminal 7A is attached prior to caulking and fixing the caulking. It is electrically and mechanically connected to the antenna electrode portion 4a. A lead wire 6a is electrically and mechanically connected to the lug terminal 7A by using a crimp terminal 8 or the like.

Further, the connection between the antenna electrode portion 4a and the lead wire 6a can be made as shown in FIGS. 3 (c) and 4, for example. The former is performed by forming the extending portion 4aa in a part of the antenna electrode portion 4a and providing the connecting terminal 7 on the extending portion 4aa. In the latter, one end of the antenna electrode portion 4a is folded back to the back side of the base member 5, and the folded portion 4ab, the antenna electrode portion 4a on the front side, and the base.
A common hole is formed in the member 5, and the connection terminal 7 is penetrated and positioned in this hole and then caulked and fixed. The lug terminal 7A is previously inserted into the connection terminal 7 before being caulked and fixed.

A control unit 10 is incorporated in the above-mentioned sheet 1, and the control unit 10 is, for example, as shown in FIG.
As shown in FIG. 5, an electric field generating means (for example, an oscillation circuit) 11 for generating a weak electric field around the antenna electrode portions 4a to 4d and a voltage amplitude of a transmission signal from the oscillation circuit 11 to the antenna electrode 4 are substantially constant. Amplitude control circuit 12 for controlling
, An information detection circuit (for example, a current detection circuit) 15 that detects information related to the transmission current of the transmission signal, and an AC-DC conversion circuit 1 that converts the output signal of the current detection circuit 15 into direct current.
6, an amplifier 17 that amplifies the output signal of the AC-DC conversion circuit 16, and a switching circuit 18 for the antenna electrode portions 4a to 4d that is connected to the current detection circuit 15 and has a plurality of switching means 18a to 18d. Connectors 19a-19d connected to the switching means 18a-18d of the circuit 18 and arranged in the housing of the control unit
And the amplitude control circuit side of the current detection circuit 15 (oscillation circuit side)
And a phase difference detection circuit 20 which is connected to the switching circuit side (antenna electrode side) and detects a phase difference between a transmission signal from the oscillation circuit and an output signal to the antenna electrode, and a phase difference detection circuit 2
An amplifier 21 for amplifying an output signal of 0, a control circuit 22 including a CPU and the like, a connector 23 arranged in the housing and connected to a battery power source (not shown), and a connector 2
Power supply circuit 24 connected between the control circuit 22 and the control circuit 22.
It consists of and. These components are housed in the same housing to form the control unit 10,
For example, the seat frame 3 in the seating portion 1a of the seat 1
It is fixed so that it is not exposed to the seating side of the passenger. To the control circuit 22 of the control unit 10, for example, an airbag device 30 having the configuration shown in FIG. 7 is connected. still,
The above-mentioned oscillation circuit 11 is configured to generate a high frequency low voltage having a frequency of about 120 KHz and a voltage of about 5 to 12 V, for example. Further, the selective switching of the switching means 18a to 18d in the switching circuit 18 is performed by the control circuit 2
It is performed based on the signal from 2.

In this control unit 10, the amplitude control circuit 12 is composed of, 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. Then, the amplitude variable circuit 13 is, for example, a programmable gain amplifier (PG
The amplitude detection circuit 14 includes a voltage amplitude detection section 14a including, for example, an operational amplifier, and an AC-DC conversion circuit 14b for converting an output signal of the detection section 14a into a direct current. And an amplifier 14c that amplifies 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 amplitude variable signal for the amplitude variable unit 13a is output from the control circuit 22.

In the control unit 10, the current detection circuit 15 includes an impedance element such as a resistor 15a connected in series with a circuit (transmission signal system) and a differential amplifier for amplifying the terminal voltage of the resistor 15a. Such as amplifier 1
5b and. 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. Then, the current detection circuit 1
The output side of the resistor 15a in 5 is connected to the connectors 19a to 19d via the switching circuit 18.

Further, as shown in FIG. 6A, for example, the phase difference detection circuit 20 separates the transmission signal from the oscillation circuit 11 and the output signal to the antenna electrodes 4 (4a to 4d) from a sine wave into a square wave. A waveform shaping circuit 20a for shaping the waveform into a wave,
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.
When the high frequency low voltage output from the oscillation circuit 11 is generated by a switching operation or the like from a single + 5V power source generated by the power source circuit 24 (when the waveform of the generated voltage is a square wave), the waveform is The shaping circuit 20a can be omitted.

The occupant detection system configured as described above operates as follows. First, when a high frequency low voltage is transmitted from the oscillation circuit 11, its voltage amplitude is detected by the detection unit 14a of the amplitude detection circuit 14, and the detection signal is A
The amplifier 1 is converted into direct current by the C-DC converter circuit 14b.
It is amplified at 4c and input to the control circuit 22. The control circuit 22 determines whether or not the detected voltage amplitude has a predetermined amplitude value, and outputs an amplitude variable signal for correcting the voltage amplitude to the predetermined voltage amplitude to the amplitude variable unit 13a. This corrects the voltage amplitude of the transmitted signal to the desired amplitude,
After that, the amplitude variable circuit 13 and the amplitude detection circuit 14 cooperate to control the amplitude to a constant value.

The transmission signal whose voltage amplitude is constant is sent through the current detection circuit 15, the switching circuit 18 (18a to 18d), and the connectors 19a to 19d to the antenna electrodes 4 (4a to 4).
d), so that the antenna electrodes 4 (4a-4
A weak electric field is generated around d). At this time, the switching circuit 18 is subjected to open / close control 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 then only the switching means 18c is closed. It is closed, and thereafter, in the same manner, switching control is performed so that only specific switching means are sequentially closed and other switching means are opened at the same time. Therefore, the specific switching means (18a
.About.18d) are closed, the transmission signal whose voltage amplitude is made constant is the current detection circuit 15, specific switching means (18a to 18d), and specific connector (19a to 1).
9d) to the specific antenna electrodes (4a-4d), so that the specific antenna electrodes (4a-4d)
A weak electric field is generated in the vicinity of, and a current having a different value according to the seating posture of the occupant seated in the sheet 1 flows. This current is detected by the current detection circuit 15, and A
The C-DC conversion circuit 16 converts the direct current to an amplifier 17
It is amplified at and input to the control circuit 22 one after another. still,
The closing order of the switching means (18a to 18d) can be performed from the opposite direction like the switching means 18d, 18c ... 18a.

On the other hand, a signal (voltage) at both ends of the current detection circuit 15, that is, a transmission signal from the oscillation circuit 11 on the amplitude control circuit side and to the antenna electrodes 4 (4a to 4d) on the switching circuit side (antenna electrode side). When the output signal is input to the phase difference detection circuit 20, the sine wave signal is shaped into a square wave by the waveform shaping circuit 20a, as shown in FIG. 8A, and the first and second flip-flop circuits 20b1. , 2
It is output to 0b2. The rising edge (arrow shown in the figure) of the square wave output on the transmission side is the first flip-flop circuit 20.
It is detected at the terminal CK of b1 and the terminal Q-bar is high (Hi
gh) output. On the other hand, on the receiving side, as shown in FIG. 6B, the rising edge of the square wave output (the arrow shown in the figure) is detected at the terminal B of the second flip-flop circuit 20b2, and only a moment from the terminal Q-bar. The low output is one-shot output. By inputting this output signal to the terminal RES of the first flip-flop circuit 20b1, the terminal Q of the first flip-flop circuit 20b1 is input.
The output of the bar is inverted to low as shown in FIG. This output becomes the phase amount (phase difference), and the integration circuit 2
It is converted into a voltage by passing 0c and is input to the control circuit 22 via the amplifier 21. The operation of detecting the phase amount is sequentially performed corresponding to the operation of detecting the transmission current to each antenna electrode by the current detection circuit 15.

The control circuit 22 is previously provided with, for example, a sheet.
A threshold value (threshold value) relating to the seating status of seated passengers (whether seated or not, adult or child)
), A threshold value (threshold value data) relating to the phase difference between the transmission signal to the current detection circuit 15 and the output signal to the antenna electrode
Data) is stored. Specifically, the threshold value regarding whether or not a passenger is seated is set as follows. For example, as shown in FIGS. 9 (a) and 9 (b), when an adult occupant P and a child occupant SP are seated in the seat 1, respectively, due to the difference in area facing the respective antenna electrodes. The level of the current flowing through each antenna electrode is different, and the current level of the adult occupant P is higher than that of the child occupant SP. Therefore,
A level slightly lower than the current level in the case of the child SP is set as the threshold value regarding whether or not the occupant is seated. still,
If the detected data is larger than this threshold value, it is determined that the occupant is seated, and if it is smaller, it is determined that the occupant is not seated. In particular, it is desirable to set this threshold value for the total sum of the currents flowing in the respective antenna electrodes,
It is also possible to set for each antenna electrode.

The threshold value for identifying the occupant is set as follows. For example, FIGS. 9A and 9B
As shown in Fig. 2, when an adult occupant P and a child occupant SP are seated in the seat 1, the level of the current flowing through each antenna electrode varies depending on the area facing each antenna electrode. Different, adult P
In the case of, the current level becomes higher than that in the case of the child occupant SP. Therefore, an intermediate current level between the adult P and the child SP is set as a threshold for discrimination.
If the detected data is larger than this threshold value, it is judged as an adult P, and if it is smaller, it is judged as a child SP. In particular, it is desirable to set this threshold value for the total sum of the currents flowing through the respective antenna electrodes, but it is also possible to set it for each antenna electrode.

On the other hand, regarding the phase difference, the average phase difference detected by the phase difference detection circuit 20 when the occupant is seated in the seat 1 and the average position detected by the presence of a person other than a person. An arbitrary value between the difference and the phase difference is set as a threshold value for determining that a person is seated. Depending on the state of the sheet (for example, getting wet with water), the upper limit and the lower limit can be set as the threshold value, and when the phase difference data exists within the range, a person is seated. It is determined that Therefore, in the control circuit 22, the threshold data concerning the seating of the occupant and the threshold data concerning the phase difference which are stored in advance, and the sitting data and the position related to the input current are stored. By comparing the phase difference data,
It is accurately determined whether the occupant seated in the seat 1 is an adult or a child, or whether the seat is wet.

Therefore, the signal data relating to the occupant's seating status and the like fetched in the control circuit 22 is previously stored in the control circuit 2.
2 is compared with the threshold value data regarding the occupant's seating condition, etc., as shown in FIG.
When the current levels of all the antenna electrodes 4a to 4d are high, it is determined that the occupant is seated in the seat 1 and the occupant is an adult P. As a result, the airbag device 30 shown in FIG. 7 is set so that the airbag can be deployed by the transmission signal from the control circuit 22. On the contrary, as shown in FIG. 9B, all the antenna electrodes 4
If the current level of a to 4d is low and lower than the threshold value for seating, the seat 1 is occupied by an occupant,
The occupant is determined to be a child SP. As a result, the airbag device 30 shown in FIG. 7 is set by the transmission signal from the control circuit 22 so that the airbag cannot be deployed. That is, the transmission signal from the control circuit 22 is set so that air cannot be expanded. That is, the transmission signal from the control circuit 22 is input to the control circuit CC of the airbag device 30, and in the latter case, the gate signal is set not to be supplied to the semiconductor switching element SW2 on the passenger side in the event of a vehicle collision. To be done. A gate signal is supplied to the semiconductor switching element SW1 on the driver's seat side. In the former case, the semiconductor switching elements SW1 and SW2 are set so that a gate signal is supplied.

Next, the processing flow of this occupant detection system.
This will be described with reference to FIGS. 10 to 14. First, as shown in FIG. 10, the ignition switch is turned on and started. Initialize in step S1,
Go to step S2. In step S2, an initial diagnosis of the communication system between the control circuit 22 and the airbag device 30 is performed. In step S3, it is determined whether the engine has started. If it is determined that the engine has started, the process proceeds to step S4. If it is determined that the start is not started, the process returns. In step S4, among the plurality of antenna electrodes 4a to 4d, the signal data and the sheet 1 related to the current flowing in each specific antenna electrode based on the weak electric field generated around the specific antenna electrode are transmitted. Phase difference data related to seating of the occupant is received.
In step S5, it is determined based on the captured data that the seat is occupied by an occupant and whether the occupant is an adult or a child. Further, in step S6, based on the determination result of step S5, the airbag device (SRS)
SRS communication is performed with 30. When step S6 ends, the process returns to step S4 again, and the processes of steps S4 to S6 are repeated. Incidentally, step S3 can be omitted.

The initial diagnosis in FIG. 10 is performed, for example, in FIG.
It is performed as shown in. First, in step SA1, fixed data is transmitted from the control circuit 22 to the control circuit CC of the airbag device 30. At step SA2, the transmission data from the airbag device 30 is received. And step S
At A3, it is determined whether the fixed data transmitted from the control circuit 22 to the airbag device 30 and the received data from the airbag device 30 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 the communication system is abnormal, fail-safe processing is performed, and, for example, a warning light is turned on. In this initial diagnosis, fixed data is transmitted from the airbag device 30 to the control circuit 22,
The transmission data from the control circuit 22 may be judged by the control circuit CC of the airbag device 30 regarding the matching.

Signal reception in FIG. 10 is performed, for example, in FIG.
It is performed as shown in. First, in step SB1, based on a signal from the control circuit 22, the switching means 18a to 18d of the switching circuit 18 are selectively selected sequentially, such as only the switching means 18a, only the switching means 18b. And the specific antenna electrodes (4a-4d) are sequentially selected. Then, in step SB2, the transmission signal data and the phase difference data to the respective antenna electrodes are fetched into the control circuit 22. Further, in step SB3, it is determined whether or not the switching of the antenna electrodes 4a to 4d based on the selective closing of the switching means 18a to 18d of the switching circuit 18 is completed. When it is judged that all the switching has been completed,
The occupant determination flow is continued. If it is determined that the switching has not been completed, the process returns to step SB1.

The occupant determination in FIG. 10 is performed, for example, in FIG.
It is performed as shown in. First, in step SC1, the signal data relating to the currents flowing through all the antenna electrodes 4a to 4d is compared with the threshold value relating to the seating condition of the occupant, and whether the actual signal data is larger than the threshold value or not. Is judged. If it is determined that the actual signal data is greater than the threshold value, the process proceeds to step SC2, and if it is determined that it is not greater, the process proceeds to step SC3. If it is determined in step SC2 that the occupant seated in the seat is an adult, the process proceeds to step SC4, in which ON data for deploying the airbag of the airbag device 30 is set, and The SRS data communication flow is continued. If it is determined in step SC3 that the occupant seated in the seat is the child SP, the process proceeds to step SC5,
The OFF data is set to prevent the airbag of the airbag device 30 from expanding, and the processing flow is continued.

The SRS data communication in FIG. 10 is performed as shown in FIG. 14, for example. First, step SD1
Then, ON data or OFF for making the airbag of the airbag device 30 in a deployable state or an undeployable state from the occupant detection unit side (control circuit 22) to the airbag device side (control circuit CC). Data and check data are transmitted. At step SD2, ON data or OFF data from the airbag device side is OK.
Receiving data or NG data and check data,
Go to step SD3. In step SD3, ON / OFF sent from the passenger detection unit side to the airbag device side
It is again determined whether or not the data and the check data are in a normal state and the reply is sent from the airbag device side to the occupant detection unit side. If it is determined to be normal (the communication system is normal), the processing flow is continued. If it is determined that the communication system is abnormal, the process proceeds to step SD4 and it is determined whether or not the fail-safe timer reaches zero. The abnormality detection of the communication system is set to three times, for example. Therefore, if it is determined that the fail-safe timer has become zero, fail-safe processing is performed and, 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 SD5 and the fail-safe timer is executed.
The rescue timer is counted and the processing flow is continued.

On the other hand, in step SE1, the airbag device side (control circuit CC) is on the occupant detection unit side (control circuit 2).
From 2), ON data or OFF data and check data for making the airbag of the airbag device 30 in a deployable state or an undeployable state are received. Then, in step SE2, the reception data is checked to determine whether or not the reception data can be normally received. Whichever judgment is made, the operation proceeds to step SE3, where O
K data or NG data and check data are transmitted to the occupant detection unit side. If it is determined in step SE2 that the communication system is normal, the OK data in step SE3
After the data transmission step, the process proceeds to step SE4. In step SE4, the data on the side of the airbag device is updated based on the OK data. As a result, the airbag is renewed and set to either the deployable state or the undeployable state. If it is determined in step SE2 that the communication system is abnormal, the process proceeds to step SE5 after the NG data transmitting step of step SE3. In step SE5, it is determined whether or not the fail-safe timer has reached zero. It should be noted that this communication system abnormality detection is, for example, 3
Has been set to times. Therefore, if it is determined that the fail-safe timer has become zero, fail-safe processing is performed and, 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 SE6, the fail-safe timer is counted, and the processing flow is continued.

According to this embodiment, the antenna electrode 4 (4
The control unit 10 is installed in the seat 1 in which a to 4d) are arranged.
In order to electrically connect the antenna electrode 4 and the control unit 10 with the lead wires 6 (6a to 6d), the wiring length of the control electrode 10 and the control unit 10 are connected to the dashboard portion or the dashboard portion. It can be made considerably shorter than when it is arranged in an engine room or the like.
Therefore, not only the cost can be reduced, but also the influence of external noise can be reduced by shortening the wiring length, and the reliability of the occupant detection function of the system can be enhanced.

Further, since the control unit 10 houses the circuit elements such as the oscillation circuit 11, the current detection circuit 15, the switching circuit 18, the control circuit 22 and the power supply circuit 24 in the same housing, it is constructed compactly. Incorporation into the sheet 1 becomes easy. In particular, since it is relatively easy to secure an arrangement space in the seat frame 3 in the seating portion 1a or in the vicinity thereof, the control unit 10 can be easily and easily incorporated even if the control unit 10 is slightly larger.

Further, by incorporating the control unit 10 into the sheet 1, the lead wires 6 (6a to 6d) connecting the antenna electrode 4 and the control unit 10 can be set to have a short wiring length. It is possible to wire the lead wires 6 (6a to 6d) without exposing them to the outer surface of the seat on the seating side of the occupant. Therefore, not only the appearance condition can be improved, but also the influence of external noise can be minimized and the reliability of the system can be enhanced.

Furthermore, since the control unit 10 is incorporated in the seat 1, even if an external impact is applied to the vehicle, it is easily damaged and can be reused. Therefore, it is desirable from the viewpoint of effective use of resources.

In particular, a plurality of antenna electrodes 4 (4a to 4d) are arranged apart from each other in the seating portion 1a of the sheet 1, and the switching means 18a to 18d of the switching circuit 18 are arranged on the respective antenna electrodes. The antenna electrodes 4 (4a-4d) facing the occupant seated in the seat 1 are connected to the oscillation circuit 11 in order by the switching due to, and a weak electric field is generated by the application of the high frequency low voltage. A current flows according to the facing area. Therefore, by detecting these currents, it is possible to easily detect whether or not the occupant is seated in the seat and whether the occupant seated in the seat is an adult or a child.

Moreover, 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 in the sheet 1. In particular, when the object is a person, it has a phase difference of a level difference that is identifiable as compared with other objects. Therefore, by detecting the phase difference in the phase difference detection circuit 20, the presence or absence of the occupant seated in the seat 1 is combined with the determination as the signal data related to the occupant identification based on the detected current. Can be accurately detected.

In particular, the air bag of the air bag device 30 is set to either the inflatable state or the inflatable state based on the judgment of whether the occupant is an adult or a child. For example, when it is determined that the occupant is the child SP because the level of the detected current is low, the airbag of the airbag device 30 is set to the undeployable state. Therefore,
Even if a vehicle collides, the airbag is not deployed, so that the child can be prevented from being damaged by the airbag.

In the control unit 10, the power supply circuit 2
While using the single power supply by 4 as the system power supply,
If the oscillator circuit 11 is configured so that a high frequency low voltage of a square wave is generated only by the positive power source, not only the power source circuit 24 and the oscillator circuit 11, but also the circuit configuration of the unit can be simplified and the system cost can be reduced. Can be significantly reduced.

Further, the antenna electrode 4 (4a-4d)
The voltage amplitude of the transmission signal transmitted to the control circuit 22 is controlled by the amplitude control circuit 12 so as to be substantially constant. Therefore, the data related to the current detected by the current detection circuit 15 and the control circuit 22 are stored. It becomes easy to compare and judge with the threshold data regarding the seating status of the occupant, and it is possible to detect with high reliability and accuracy.

FIG. 15 shows another embodiment of the occupant detection system according to the present invention, which is basically the same as the above embodiment. The difference is that the backrest 1 of the seat 1 is different.
That is, the plurality of antenna electrodes 4 (4a to 4d) are spaced apart and symmetrically arranged in b, and the antenna electrode 4 is not arranged in the seating portion 1a.

According to this embodiment, as shown in FIG. 4A, the occupant seated in the seat has a large area facing all the antenna electrodes 4a to 4d and a large detected current. Is determined to be an adult P, and as shown in FIG. 7B, if the area facing the antenna electrodes 4a to 4d is small and the level of the detected current is low, the occupant is a child SP. Is easily determined.

The present invention is not limited to the above-described embodiment at all, and the number of antenna electrodes (antenna electrode portions) arranged on the sheet can be appropriately increased or decreased, and the shape thereof can be other than square. It can be formed into a rectangular shape, a strip shape, etc.
It is also possible to cover the antenna electrode portion arranged on the cover member with an insulating cover member. In addition to the oscillator circuit, the electric field generating means may be configured to generate a high frequency low voltage of a substantially square wave by a switching operation using a positive power source of the clock signal of the control circuit, or to generate a high frequency low voltage of the control circuit. The frequency can be appropriately divided and generated, and the output frequency thereof can be set to a value other than 120 KHz according to the situation such as the passenger compartment, and the voltage is also outside the range of 5 to 12V. But you can use it.
Further, the amplitude control circuit and the phase difference detection circuit may be omitted depending on the accuracy of the system power supply and the function expected of the system. Further, the information detection circuit is, of course, a current detection circuit which directly detects the current flowing through the antenna electrode,
It also includes a circuit that indirectly detects based on information such as voltage, power, and waveform that are related to the flowing current. Further, the occupant determination is performed by using a threshold value stored in advance in the control circuit and a signal data related to the current flowing through the actual antenna electrode.
In addition to comparison with passenger seats, various seating patterns for passenger seats
Data related to seating, seating posture, etc. is stored in advance,
By comparison with this, it is possible to determine whether or not the occupant is seated and whether or not the occupant is an adult.

[0049]

As described above, according to the present invention, since the control unit is incorporated in the sheet in which the antenna electrode is arranged, the antenna electrode and the control unit are read.
The length of the wiring can be shortened when electrically connecting with the wire. Therefore, not only the cost can be reduced, but also the influence of external noise can be mitigated by shortening the wiring length, and the reliability of the occupant detection function of the system can be enhanced.

Further, since the control unit has a compact structure in which at least the circuit elements including the electric field generating means, the information detecting circuit, the switching circuit and the control circuit are housed in the same housing, the control unit can be incorporated in the sheet. It will be easier. In particular,
Since it is relatively easy to secure an arrangement space in or near the seat frame in the seating portion, the control unit can be easily and easily incorporated even if it is slightly larger.

Further, by incorporating the control unit into the sheet, a lead for connecting the antenna electrode and the control unit is provided.
Since the wiring length of the lead wire can be set short, the lead wire can be wired without exposing the lead wire to the outer surface of the seat on the seating side of the occupant. Therefore, not only the appearance condition can be improved, but also the influence of external noise can be minimized and the reliability of the system can be enhanced.

Further, since the control unit is incorporated in the seat, even if an external impact is applied to the vehicle, it is easily damaged and can be reused. It is desirable from the viewpoint of effective use of resources.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a basic operation of an occupant detection system according to the present invention, in which FIG. 1 (a) is a diagram showing an electric field distribution around an antenna electrode, and FIG. 1 (b) is a diagram showing the antenna electrode. The figure which shows the electric field distribution when an object exists in the vicinity.

2A and 2B are views showing a vehicle interior portion of an occupant detection system according to the present invention, in which FIG. 2A is a side view showing an arrangement state of antenna electrodes on a sheet, and FIG. The front view of FIG.

3A and 3B are specific configuration diagrams of the antenna electrode shown in FIG. 2, in which FIG. 3A is a plan view, FIG. 3B is a cross-sectional view of a main part of FIG. 3A, and FIG. FIG. 4 is a plan view of a main part showing a different embodiment of FIG.

FIG. 4 is a cross-sectional view of an essential part showing another embodiment of the connection state of the connection terminal to the antenna electrode shown in FIG. 3 (b).

FIG. 5 is a circuit block diagram of an occupant detection system according to the present invention.

6A is a circuit block diagram of a specific example of the phase difference detection circuit shown in FIG. 5, and FIG. 6B is a circuit block diagram of a waveform shaping circuit.

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

8A and 8B are diagrams for explaining the operation of the phase difference detection circuit shown in FIG. 6, in which FIG. 8A is a waveform diagram of a transmission signal and an output signal of a first flip-flop circuit, and FIG. 6A is a waveform diagram of the output signal and the output signal of the second flip-flop circuit, and FIG. 9C is a diagram showing a detection state of the phase amount from the output signals of the first and second flip-flop circuits.

FIG. 9 is a diagram for explaining a seated state of an occupant in a seat, FIG. 9A is a diagram showing a seated state of an adult;
FIG. 2B is a diagram showing a seated state of a child.

FIG. 10 is a flowchart for detecting an occupant by the occupant detection system according to the present invention.

11 is a flowchart of the initial diagnosis shown in FIG.

12 is a flowchart of the signal reception shown in FIG.

FIG. 13 is a flowchart for occupant determination shown in FIG.

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

FIG. 15 is another embodiment showing the arrangement of the antenna electrodes on the seat according to the present invention, wherein FIG. 15 (a) is a front view showing a state in which an adult is seated on the seat, FIG. 1B is a front view showing a state where a child is seated.

FIG. 16 is a circuit block diagram of an airbag device according to a conventional example.

FIG. 17 is a circuit block diagram of an improved airbag device according to a conventional example.

[Explanation of symbols]

1 sheet 1a Seating section 1b Backrest 3 sheet frames 4 (4a to 4d) Antenna electrode (antenna electrode portion) 5 base members 6 (6a-6d) lead wire 7 connection terminals 7A lug terminal 8 Crimp terminal 9 connectors 10 control unit 11 Electric field generating means (oscillation circuit) 12 Amplitude control circuit 13 Amplitude variable circuit 14 Amplitude detection circuit 15 Information detection circuit (current detection circuit) 16 AC-DC conversion circuit 17,21 amplifier 18 (18a-18d) switching circuit 19a to 19d Connector (terminal) 20 Phase difference detection circuit 22 Control circuit 24 power supply circuit 30 airbag device SS1, SS2 safing sensor SQ1, SQ2 squib SW1, SW2 Semiconductor switching element CC control circuit GS Electronic acceleration sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Ofuji, 1-1, Shin-Urashima-cho, Kanagawa-ku, Yokohama, Kanagawa Pref., Nippon Electric Robot Engineer Ring Co., Ltd. (56) Reference JP-A-9-46205 (JP, 46-205) A) JP-A-1-44356 (JP, A) JP-A-9-207644 (JP, A) JP-A-7-237484 (JP, A) JP-A-9-509118 (JP, A) (58) Survey Areas (Int.Cl. ⁷ , DB name) B60N 5/00 B60R 21/32

Claims (5)

(57) [Claims] 1. An antenna electrode arranged on a sheet is connected to an output of an oscillating circuit through a current detecting circuit, and the current detecting circuit is responsive to an electric field generated around the antenna electrode by the oscillating circuit. An occupant detection system including a control circuit for detecting a current flowing from the antenna electrode to determine the seating status of the occupant in the seat based on the detected current, wherein the seat has a plurality of antenna electrodes. A switching circuit for selectively switching / connecting the oscillation circuit to a specific antenna electrode among the plurality of antenna electrodes is disposed between the current detection circuit and the plurality of antenna electrodes. The current detection circuit is connected to the antenna electrode from the oscillation circuit according to an electric field generated around the specific antenna electrode selected by the switching circuit. The control circuit is configured to house the oscillation circuit, the current detection circuit, the control circuit, and the switching circuit in the same housing, and the control unit is incorporated in a seat. Characteristic passenger detection system. 2. The occupant detection system according to claim 1, wherein at the time of a collision, air that is set to either an inflatable state or an uninflatable state based on a determination result of the control circuit. An occupant detection system, further comprising a bag device. 3. The occupant detection system according to claim 1, wherein the control unit is arranged in a seating portion of a seat or a frame portion of a backrest portion or in the vicinity thereof. 4. The occupant detection system according to claim 1 or 2, wherein the control unit is incorporated in a seat portion that is as close as possible to the plurality of antenna electrodes. 5. The plurality of antenna electrodes and the control unit are electrically connected by lead wires, and the lead wires are wired so as not to be exposed from a seat on a seat side of an occupant. Or the occupant detection system according to 2.