JP3443698B2 - 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 in particular, an airbag of an airbag device can be deployed according to the seating condition of an occupant 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 unexpandable 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.

As shown in FIG. 21, for example, this airbag device has a safing sensor SS1 and a squib SQ.
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, according to this airbag device,
For example, as shown in FIG. 22A, when the adult P is seated in the seat 1, the above-described passenger protection effect can be expected in the event of a collision. However, as shown in FIG. (B), the passenger seat sheet - Child and fixed on sheet 1 sheet - if bets 2 infant SP is sitting backward (R ear F acing I nfant S eat: less, In the case of RFIS), there is a concern that the deployment of the airbag may adversely affect the infant SP, so it is desirable that the airbag does not deploy even if a vehicle collides. Further, as shown in FIG. 3C, when the infant SP is sitting forward on the child seat 2 fixed on the seat 1 in the passenger seat ( F orwa
rd F acing C hild S eat: hereinafter referred to as FFCS) to the air bag children S by the deployment of the air bag
Since it is feared that the face of P will be covered, it is desirable that the airbag does not deploy even if a vehicle collides, as in the case of RFIS.

[0006]

Therefore, conventionally, in order to deal with such a problem, an airbag device as shown in FIG. 23, for example, 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, as the sensor SD, it is proposed to use a weight sensor for measuring the weight and to take an image of an occupant seated in the seat with a camera and perform image processing to determine whether it is an adult P or a child SP. Has been done.

According to the former method, it is possible to roughly judge whether the occupant is an adult P or a child SP, and based on this result, the airbag can be inflated or undeployable. Although it is possible to set and avoid unforeseen circumstances in the event of a car collision, there are large individual differences in weight, and children may be heavier than adults, so not only lack accuracy but also RFIS, FFCS.
There is a problem that it is not possible to determine which state of

According to the latter method, the occupant's seating condition, the determination as to whether the occupant is an adult P or a child SP, a child seat
Although it is possible to judge whether or not the child is in the state of RFIS or FFCS fairly accurately, it is necessary to perform image processing on the imaged data taken by the camera and make a comparison judgment with various patterns. In addition, there is a problem that the processing device becomes complicated and expensive.

Therefore, it is an object of the present invention to accurately determine the occupant's seating condition, whether the occupant is an adult or a child, the seating condition of a child in a child seat, etc., and is relatively inexpensive. An object of the present invention is to provide an occupant detection system and an occupant detection method.

[0010]

Therefore, in order to achieve the above-mentioned object, the present invention provides a first electrode provided on one of a seating surface or a backrest surface of a seat, and a seating surface or a backrest surface of the seat. An oscillation circuit for generating a weak electric field between a specific electrode and an electrode other than the specific electrode among the first to third electrodes, and the second and third electrodes provided on the other side of The output from this oscillation circuit is received, and the first to third
Select one electrode in sequence from the
Output is used as a transmission electrode and is not selected
Transmission / reception off using electrodes other than specific electrodes as receiving electrodes
Based on the output signal of the conversion circuit, the current / voltage conversion circuit that detects the displacement current flowing based on the weak electric field generated between the transmission electrode and the reception electrode, and converts it into a voltage, and the output signal of the current / voltage conversion circuit. And a control circuit for detecting the seating status of the seat , wherein the control circuit stores the seating pattern stored in advance.
And a sitting pattern based on the output signal of the current / voltage conversion circuit
By comparing the emissions characterized by determining the seating pattern, the second aspect of the present invention may further include an air bag device having a function to deploy the air bag on the basis of the collision,
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 either a deployable state or an undeployable state.

Further, a third invention of the present invention is characterized in that the oscillation circuit generates a high frequency low voltage, and a fourth invention is a load current detecting circuit for detecting a load current flowing through the transmitting electrode. A fifth invention is characterized in that the first electrode is composed of a plurality of electrodes, and the sixth invention is based on an output signal of the current-voltage conversion circuit. further comprising a phase detection circuit that detects the phase amount Te, the phase amount is characterized in that it is supplied to the control circuit, the fourth invention of the seventh, which is provided on the front surface of the seating surface of said seat Is further provided.

Further, an eighth invention of the present invention is that the first electrode provided on one of the seating surface or the backrest surface of the seat and the second electrode provided on the other of the seating surface or the backrest surface of the seat.
And one of the first to third electrodes between the first and third electrodes.
The electrodes are sequentially used as the transmission electrodes and the other electrodes are used as the reception electrodes to generate a weak electric field, detect the displacement current flowing in the reception electrodes, and detect the displacement current from the reception electrodes every time the transmission electrodes change.
The ninth aspect of the present invention is characterized in that the seating situation in the seat is detected based on the detected and weak electric field, and the ninth invention is characterized in that the airbag is controlled based on the detected seating situation.
It shall be the.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the basic principle of the present invention will be described with reference to FIGS. The occupant detection system and the occupant detection method according to the present invention are basically a weak electric field (Elect) generated between two electrodes arranged in a sheet.
It uses the disturbance of ric field. First, Fig. 1
As shown in (a), when the oscillation circuit 10 that generates a high frequency low voltage is connected to the electrode E1 and the electrode E2 is connected to the ground, an electric field is generated in the electrodes E1 and E2 based on the potential difference between the electrodes. The displacement current Id flows on the side of the electrode E2. In this state, as shown in FIG.
When the object OB is present in the electric field, the electric field is disturbed and a displacement current Id different from the displacement current Id is generated on the electrode E2 side.
d1 will flow. Most objects OB are electrically represented by conductance and capacitance, and are coupled to the ground through the capacitance.
The current path at this time is expressed as shown in FIG.

When the object OB is not on the seat of the automobile, the shunting current flowing to the ground is almost zero, and the transmitting current (displacement current) flowing to the electrode E2 side increases. If the sheet is an object O
When B is present, a shunting current is generated as shown in FIG. 2, so that the transmitting current flowing on the side of the electrode E2 is reduced. Therefore, by utilizing this phenomenon, the seating condition of the occupant in the seat can be detected. In particular, by increasing the number of electrodes, it becomes possible to obtain much information about an object including an occupant on the seat, and it is possible to more accurately detect the seating condition of the occupant 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 conventional example shown in FIGS. 21 to 23 are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 3 shows a seat according to the present invention, which is a seat 1 in the passenger seat.
A plurality of electrodes are arranged on the surface side of. Specifically, for example, rectangular electrodes E1 and E2 are provided on the seating surface 1a,
On the backrest surface 1b, electrodes E3 and E4 having substantially the same shape are separately arranged. The electrode E is also provided on the front surface 1c.
5, E6 can be added and arranged. These electrodes are made of conductive cloth in consideration of the sitting comfort of the occupant, but thread-like metal is woven into the sheet cloth surface, conductive cloth is attached to the cloth surface, or metal is used. It is also possible to arrange a plate or the like. These electrodes E1 to E4 are connected and incorporated in the circuit shown in FIG. 4 (FIG. 5).

In FIG. 4, the occupant detection system has an oscillating circuit 10 for generating a high frequency low voltage having a frequency of about 100 KHz and a voltage of about 10 to 12 V, a load current detection circuit 11, and a transmission / reception switching circuit 12, for example. A current / voltage conversion circuit 13 having an amplification function, a detection circuit (demodulation circuit) 14 having a bandpass function and an AC-DC conversion function (unnecessary noise removal function), an amplification circuit 15, and an offset conversion circuit 16. , A control circuit 17 such as MPU,
The airbag device 18 is included. FIG. 5 is FIG.
The circuit of FIG.
Is composed of, for example, a first amplifier circuit 15A and a second amplifier circuit 15B each having a gain G of 1 times and 100 times, and an analog selection circuit for selecting output signals of the first and second amplifier circuits 15A and 15B. 19 is provided, and the analog selection circuit 19 is controlled by the control circuit 17.

In this system, the load current detection circuit 11 is composed of, for example, an impedance element such as a resistor 11a connected in series with 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 one selected electrode (referred to as a transmission electrode) among the electrodes E1 to E4 to the output side of the oscillation circuit 10, and a transmission electrode. Other electrodes (referred to as receiving electrodes) other than the above are comprised of switching means Ba to Bd for connecting to the current / voltage conversion circuit 13, and switching of each switching means is controlled by the control circuit 17. The transmission / reception switching circuit 12 is preferably composed of a multiplexer circuit. The current / voltage conversion circuit 13 includes, for example, an impedance element such as a resistor 13a that converts a displacement current flowing on the receiving electrode side into a voltage, and an amplifier 13 that amplifies 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 that are selected and connected all at once to the output side of the second amplification circuit 15B, and four switching means 19 that are selected and connected all at once to the output side of the first amplification circuit 15A. It is composed of a switching means 19b.

The system configured as described above operates as follows. First, when only the switching means Aa of the transmission / reception switching circuit 12 is connected to the output side of the oscillation circuit 10 based on the signal from the control circuit 17, 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 oscillator 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 this detection circuit 14, for example, a signal of about 100 KHz is band-passed and
Unwanted noise components are removed based on the C-DC conversion function and output to the first and second amplification circuits 15A and 15B. The output signals of the first and second amplifier circuits 15A and 15B are supplied to the offset conversion circuit 16 and the analog selection circuit 19 respectively.
Are appropriately selected by the operations of and and are output to the control circuit 17. For example, when the output signal from the detection circuit 14 is measurable in the full range, only the four switching means 19b of the analog selection circuit 19 are simultaneously selected and connected to the output side of the first amplification circuit 15A. Further, when the output signal is small and it is difficult to measure a subtle change in the full range, 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 first and second
The output signals from the amplifier circuits 15A and 15B are subjected to A / D conversion 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 / changed to the voltage conversion circuit 13, a high frequency low voltage is applied from the oscillation circuit 10 to the transmission electrode E2,
A displacement current flows through 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. It is processed in the same manner as described above and stored in the control device 17 as data. Then, the switching means Ac
Connect only the output side of the oscillator circuit 10, and connect 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, E4. The load current flowing through the transmission electrode E3 is detected by the load current detection circuit 11, and the data R
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 are connected / 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 a voltage by the resistor 13a, amplified by the amplifier 13b, and output to the detection circuit 14. The transmission electrode E
The load current flowing through the detector 4 is detected by the load current detection circuit 11, and is detected as data R (4, 4) described later by the detection circuit 1.
4 is output. The controller 17 is processed in the same manner as described above.
Is stored as data.

Then, the control circuit 17 calculates the seating pattern by arithmetically processing these data. The control circuit 17 stores various seating patterns in advance, and the seating patterns calculated by data based on various combinations of the transmission electrodes and the reception electrodes of the electrodes E1 to E4 are stored in advance. The seating pattern is compared with the stored seating pattern to extract and determine the seating pattern. In this control circuit 17, for example, the seating pattern shown in FIGS.
Are subject to judgment. Specifically, as shown in FIG. 7, the seat 1 has an occupant pattern in which no passenger is seated, and as shown in FIG. 8, the child seat 2 is seated in the FFCS state in the child seat 2. FFCS pattern, RFIS pattern in which child SP is seated in the state of RFIS in child seat 2 as shown in FIG. 9, and seat as shown in FIG.
11B is a pattern in which an adult P is seated on the seat 1, and the electrodes E1 to E4 are appropriately selected and various combinations of the transmitting electrode and the receiving electrode are used to obtain the patterns shown in FIGS. The data shown is obtained. Incidentally, FIG. 11A is a general formula R (i, j) representing these data, i = j represents the transmission data, i ≠ j represents the reception data, and
i represents a transmitting electrode and j represents a receiving electrode. The control circuit 17 performs arithmetic processing using 16 pieces of data for each pattern to extract the characteristics of the seating pattern. For example, FFCS is used to extract the features of this seating pattern.
In the case of, as shown in FIG. 12, various thresholds TH1 to TH
9 and R (i, j) are compared, and when the conditions shown in the figure are satisfied, it is determined that the FFCS pattern has the characteristics, and the FF
The seating pattern of the CS is determined.

When the seating pattern is detected and specified by the control circuit 17, a signal based on the detected seating pattern is transmitted to the airbag device 18. For example, seating pattern is vacant, FFC
In the case of S or RFIS, a signal is sent to the airbag device 18 so that the airbag will not be deployed even if a vehicle collides, and the airbag will be deployed in other patterns. A signal for setting to 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 that no gate signal is supplied to the semiconductor switching element SW2 on the passenger side at the time of a collision. A gate signal is supplied to the semiconductor switching element SW1 on the driver's seat side. In the latter case, the semiconductor switching elements SW1 and SW2 are set so that the gate signal is supplied.

Next, the processing flow of this occupant detection system.
This will be described with reference to FIGS. 13 to 17. First, as shown in FIG. 13, 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 17 and the airbag device 18 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, signal data is received based on various combinations of transmitting electrodes and receiving electrodes. Then, in step S5, the seating pattern of the occupant is determined based on the captured data. Further, in step S6, communication is performed with the airbag device 18 based on the determination result in step S5. When step S6 ends, the process returns to step S4 again, and the processes of steps S4 to S6 are repeated.

The initial diagnosis in FIG.
It is performed as shown in. First, in step SA1, fixed data is transmitted from the control circuit 17 to the control circuit CC of the airbag device 18. At step SA2, the transmission data from the airbag device 18 is received. And step S
At A3, 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 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 sent from the airbag device 18 to the control circuit 17,
The transmission data from the control circuit 17 may be judged by the control circuit CC of the airbag device 18 regarding the matching.

The signal reception in FIG. 13 is performed, for example, in FIG.
It is performed as shown in. First, in step SB1, one specified transmission electrode is selected from the plurality of electrodes E1 to E4 arranged in sheets by the switching means Aa to Ad. In step SB2, the switching means Ba
Three electrodes other than the transmitting electrode are selected as the receiving electrodes by ~ Bd. Then, in step SB3, the control circuit 17 receives the reception signal data of each reception electrode and the transmission signal data of the transmission electrode via the analog selection circuit 19.
Further, in step SB4, it is determined whether or not the selection / combination switching of the transmitting electrode and the receiving electrode for each of the electrodes E1 to E4 has been completed. When it is determined that the switching is 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. 13 is performed, for example, in FIG.
It is performed as shown in. First, at step SC1, it is judged whether or not the seated reception pattern (RV pattern) is equal to the FFCS pattern stored in advance in the control circuit 17. If it is determined that the two patterns are equal, the process proceeds to step SC2, where OFF data is set to prevent the airbag of the airbag device 18 from expanding and the processing flow is continued. Also, step SC
If it is determined that both patterns are not equal in 1, the process proceeds to step SC3. At step SC3, it is judged whether or not the seated reception pattern (RV pattern) is equal to the RFIS pattern stored in advance in the control circuit 17. If both patterns are judged to be equal, the routine proceeds to step SC2, where OFF data for preventing the airbag of the airbag device 18 from being deployed is set. If it is determined in step SC3 that both patterns are not equal, the process proceeds to step SC4. At step SC4, it is judged whether or not the reception pattern (RV pattern) in the seated state is equal to the Empty pattern stored in the control circuit 17 in advance. If both patterns are judged to be equal, the routine proceeds to step SC2, where OFF data for preventing the airbag of the airbag device 18 from being deployed is set. If it is determined in step SC4 that the two patterns are not equal, in step SC5 the ON data for inflating the airbag of the airbag device 18 is set and the SRS data communication flow is set. Continued to.

The SRS data communication in FIG. 13 is performed as shown in FIG. 17, for example. First, step SD1
Then, ON data or OFF for making the airbag of the airbag device 18 in a deployable state or an undeployable state from the occupant detection unit side (control circuit 17) 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 1).
From 7), ON data or OFF data and check data for making the airbag of the airbag device 18 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, a plurality of electrodes E1 to E4 are arranged on the front surface side of the sheet 1, and between one selected transmission electrode and a reception electrode other than the transmission electrode. Since a weak electric field is generated by the application of the high frequency and low voltage, a displacement current related to the seating pattern of the occupant on the seat flows on the receiving electrode side. Therefore, the seating pattern of the occupant can be determined by judging the characteristic pattern of this displacement current.
Can be accurately detected. For this reason, the airbag of the airbag device 18 can be set to either a deployable state or an undeployable state.

In particular, the sheet 1 has four electrodes E1 to E4.
Since the electrodes are separated from each other, there can be 16 combinations of the transmitting electrode and the receiving electrode as shown in FIG. 11 (a), and the number of data obtained is 16 sheets. 1
The seating pattern can be judged more accurately.

The control circuit 17 includes, for example, FIGS.
Since a current pattern characterized by a current flowing through each electrode based on four types of seating patterns shown in 0 is stored in advance as a seating pattern, the transmitter electrode and the receiver electrode are appropriately combined. The actual sitting pattern is detected with high accuracy by comparing the received signal data obtained by the above-mentioned processing with various seating patterns stored in advance and extracting the corresponding stored sitting pattern. You can

By the way, with respect to the above-mentioned four seating patterns, the seating patterns can be accurately determined, but when the seat 1 is wetted, for example, the displacement current flowing to the receiving electrode side is It may increase and it may be difficult to distinguish from the seating pattern shown in FIG. In such cases,
For example, application of the occupant detection system shown in FIGS. 18 to 19 is suitable. This system is basically almost the same as the system shown in FIGS. The difference is that the oscillator circuit 1
The addition of the phase detection circuit 20 for detecting the phase amount based on the output signal of 0 and the output signal of the current / voltage conversion circuit 13, and the switching means 19c for selecting the output signal of the phase detection circuit 20 in the analog selection circuit 19A. Is added. The phase detection circuit 20 includes, for example, waveform shaping circuits 20a and 20a for separately shaping a transmission signal and a reception signal from a sine wave to a square wave, a first flip-flop circuit 20b1, and a second flip-flop circuit 20b.
2 and an integrating circuit 20c.

The phase detection method by this system is performed as follows. When the transmission and reception sine wave signals are input to the waveform shaping circuits 20a and 20a, the sine wave signals are changed as shown in FIG.
As shown in 0 (a), it is shaped into a square wave,
Is output to the flip-flops 20b1 and 20b2.
A rising edge (arrow shown in the figure) of the square wave output on the transmitting side is detected at the terminal CK of the first flip-flop 20b1, and the terminal Q-bar becomes a high (Hi) output. On the other hand, on the receiving side, as shown in FIG. 2B, the rising edge (arrow shown in the figure) of the square wave output is the second flip-flop circuit 2.
Detected at the terminal B of 0b2, the terminal Q-bar outputs the Low output for one shot only for a moment. This output signal is sent to the terminal RES of the first flip-flop circuit 20b1.
Input to the first flip-flop circuit 2
The output of the terminal Q-bar of 0b1 becomes low as shown in FIG. This output becomes the phase amount, and the integration circuit 2
It is converted into a voltage by passing through 0c and is taken into the control circuit 17 as phase data. Incidentally, this data is taken into the control circuit 17 together with the reception signal data and the transmission signal data of each reception electrode in step SB3 of FIG.

According to this embodiment, the number of data is 16 depending on the combination of the transmitting electrode and the receiving electrode, and 12 more phase difference data between the transmitting signal and the receiving signal are added. -The amount of data will increase significantly. Therefore, the seating pattern and posture of the occupant, the wetness of the seat 1 and the like can be detected in detail, and the occupant's detection performance and the reliability of the determination can be improved.

The present invention is not limited to the above-described embodiment at all, and for example, the shape of the electrodes arranged in the sheet is not only rectangular but also circular, elliptical, or polygonal except square. You can also do it. Further, the number of electrodes arranged may be increased or decreased to a number other than four and six. The transmitter electrode is configured such that one electrode is selected, but it is also possible to configure a plurality of electrodes as the transmitter electrode,
In this case, the obtained data will increase significantly. The output frequency of the oscillator circuit is 1 depending on the detection target.
It can be set to a value other than 00 KHz. Further, the airbag device may use a mechanical sensor in addition to the electronic acceleration sensor.

[0035]

As described above, according to the present invention, a plurality of electrodes are arranged on the front surface side of the sheet, and between the selected one transmission electrode and the reception electrodes other than the transmission electrode. Since a weak electric field is generated by applying a high frequency low voltage to the sheet, a displacement current related to the seating pattern of the occupant on the seat flows on the receiving electrode side. Therefore, the seating pattern of the occupant can be determined by judging the characteristic pattern of this displacement current.
Can be accurately detected. Therefore, the airbag of the airbag device can be set to either a deployable state or an undeployable state.

Particularly, if the four electrodes are arranged apart from each other in the sheet, the number of combinations of the transmitting electrode and the receiving electrode can be increased and the number of obtained data can be increased. Therefore, the seating pattern of the occupant in the seat can be determined more accurately.

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

[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) shows electrodes E1 and E.
A diagram showing an electric field distribution between the two electrodes, FIG.
The figure which shows the electric field distribution when an object exists between them.

FIG. 2 is a schematic equivalent circuit diagram of FIG.

FIG. 3 is a perspective view of a seat of an occupant detection system according to the present invention.

FIG. 4 is a circuit block diagram of an occupant detection system according to the present invention.

5 is a specific circuit block diagram of FIG.

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

FIG. 7 is a diagram showing an electric field distribution between electrodes when an occupant is not present in the seat according to the present invention, in which FIG. 7A shows an electrode E1 as a transmitting electrode and electrodes E2 to E4 as receiving electrodes. (B) is an electric field distribution diagram when the electrode E2 is used as a transmission electrode, and (c) is an electric field distribution diagram when the electrode E3 is used as a transmission electrode. ) Is an electric field distribution diagram when the electrode E4 is used as a transmission electrode.

FIG. 8 is a diagram showing an electric field distribution between electrodes when a child is seated in a FFCS state on a child seat on the seat according to the present invention, and FIG. Is a transmission electrode and the electrodes E2 to E4 are reception electrodes. FIG. 7B is an electric field distribution diagram when the electrode E2 is a transmission electrode. FIG. 6C is an electrode E3 transmission electrode. The electric field distribution map when the electrode E4 is used as a transmission electrode.

FIG. 9 is a diagram showing an electric field distribution between electrodes when a child is seated on a child seat on the seat according to the present invention in a state of RFIS, and FIG. 9 (a) shows an electrode E1. Is a transmission electrode and the electrodes E2 to E4 are reception electrodes. FIG. 7B is an electric field distribution diagram when the electrode E2 is a transmission electrode. FIG. 6C is an electrode E3 transmission electrode. The electric field distribution map when the electrode E4 is used as a transmission electrode.

FIG. 10 is a diagram showing an electric field distribution between electrodes when an adult occupant is seated in the seat according to the present invention, and FIG. 10A shows an electrode E1 as a transmission electrode and electrodes E2 to E2. The electric field distribution diagram when E4 is the receiving electrode, the same figure (b) is the electric field distribution diagram when the electrode E2 is the transmitting electrode, and the same figure (c) is the electrode E3.
Of the electric field when the transmission electrode is
4 is an electric field distribution diagram when 4 is a transmission electrode.

FIG. 11 is a diagram showing signal data received by respective electrodes in various seating patterns of the seat according to the present invention, and FIG. 11 (a) is a symbol diagram showing the signal data. , (B) is a signal data diagram in the state of FIG. 7, (c) is a signal data diagram in the state of FIG. 8, (d) is a signal data diagram in the state of FIG. 9,
FIG. 10E is a signal data diagram in the state of FIG.

FIG. 12 is a calculation formula for determining an FFCS pattern among various seating patterns of the seat according to the present invention.

FIG. 13 is a flowchart for detecting an occupant of the occupant detection system according to the present invention.

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

FIG. 15 is a flowchart of the signal reception shown in FIG.

FIG. 16 is a flowchart for occupant determination shown in FIG.

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

FIG. 18 is a circuit block diagram showing another embodiment of the occupant detection system according to the present invention.

19A is a specific circuit diagram of the phase detection circuit shown in FIG. 18, and FIG. 19B is a specific circuit diagram of the waveform shaping circuit of FIG.

20A and 20B are diagrams for explaining the phase detection operation of FIG. 19A, wherein FIG. 20A is a diagram showing an output signal waveform of the first flip-flop, and FIG. 2 is a diagram showing an output signal waveform of the flip-flop of FIG. 2, FIG.
The figure which shows the state which detects a phase amount from the output signal of a 2nd flip-flop.

FIG. 21 is a circuit block diagram of an airbag device according to a conventional example.

FIG. 22 is a diagram showing various seating patterns, FIG. 22 (a) showing a state in which an adult occupant is seated in the seat, and FIG. 22 (b) showing a state of RFIS. Figure, (c)
Shows a state of FFCS.

FIG. 23 is a circuit block diagram of an improved airbag device according to a conventional example.

[Explanation of symbols]

1 sheet 2 child seats 10 oscillator circuit 11 Load current detection circuit 12 Transmit / receive switching circuit 13 Current / voltage conversion circuit 14 Detection circuit 15 Amplification circuit 16 Offset conversion circuit 17 Control circuit 18 Airbag device 19, 19A analog selection circuit 20 Phase detection circuit E1-E6 electrodes SS1, SS2 safing sensor SQ1, SQ2 squib SW1, SW2 Semiconductor switching element CC control circuit GS Electronic acceleration sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-301119 (JP, A) JP-A-10-236267 (JP, A) JP-A-9-277892 (JP, A) International Publication 95/021752 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60R 21/32

Claims (9)

(57) [Claims] 1. A first electrode provided on one of a seating surface and a backrest surface of a seat, second and third electrodes provided on the other of the seating surface and a backrest surface of the seat, and the first electrode. Among the third to third electrodes, an oscillation circuit for generating a weak electric field between a specific electrode and an electrode other than the specific electrode, and an output from the oscillation circuit, and the first to the third electrodes.
Select one electrode from the poles sequentially as the specific electrode
The output is supplied to serve as a transmission electrode and is not selected.
Transmission using an electrode other than the specific electrode as a receiving electrode
A reception switching circuit, a current / voltage conversion circuit that detects a displacement current flowing based on a weak electric field generated between the transmission electrode and the reception electrode, and converts the displacement current into a voltage; and A control circuit for detecting a seating condition on the seat based on an output signal , wherein the control circuit stores a seating pattern stored in advance;
Seating pattern based on the output signal of the current / voltage conversion circuit
The occupant detection system is characterized by determining the seating pattern by comparing with the passenger seat . 2. An airbag device having a function of deploying an airbag based on a collision is further provided, and data based on a detection result of the control circuit is transmitted to the airbag device, and the airbag of the airbag device is transmitted. The occupant detection system according to claim 1, wherein the bag is set to either a deployable state or a non-deployable state. 3. The occupant detection system according to claim 1, wherein the oscillating circuit generates a high frequency low voltage. 4. The occupant detection system according to claim 1 , further comprising a load current detection circuit that detects a load current flowing through the transmission electrode. Wherein said first electrode, an occupant detection system according to claim 1 or 2, characterized in that it is composed of a plurality of electrodes. 6. A phase detection circuit for detecting a phase amount based on an output signal of the current-voltage conversion circuit, the phase amount being supplied to the control circuit. The occupant detection system according to any one of 5 above. 7. The apparatus according to claim 1, further comprising a fourth electrode provided on the front surface of the seating surface of the seat.
The occupant detection system according to any one of 1 to 6 . 8. A first electrode provided on one of the seating surface and the backrest surface of the seat, and a second electrode and a third electrode provided on the other of the seating surface and the backrest surface of the seat ,
One electrode is sequentially transmitted from the first to third electrodes
And generate a weak electric field using the other electrode as the receiving electrode ,
A displacement current flowing through the receiving electrode is detected based on the weak electric field, and a change from the receiving electrode is detected every time the transmitting electrode changes.
A method for detecting an occupant, characterized in that a seating condition on the seat is detected based on the detected displacement current. 9. The occupant detection method according to claim 8, wherein the airbag is controlled based on the detected seating condition.