JP2001322528A - Occupant detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an occupant detecting system capable of precisely detecting a distance between an occupant and an air bag device with the simple constitution. SOLUTION: This occupant detecting system 10 connects either one of transmitting receiving antennas 12 and 14 or a correcting antenna 22 to a processing means 20 by a changeover switch 24. When selecting the correcting antenna 22, radio wave amplitude detected by the processing means 20 is stored in a correcting computer 30 as correction data. While, when selecting the transmitting receiving antennas 12 and 14, the radio wave amplitude detected by the processing means 20 is inputted to the correcting computer 30 as a detecting value, and is corrected by the correction data. Thus, a distance between the occupant 60 and the air bag device 40 for a front passenger seat can be accurately detected by eliminating influence of a temperature change in a vehicle 50.

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 for detecting an occupant approaching an airbag device or the like.

[0002]

2. Description of the Related Art As an airbag device, not only an airbag device of a type in which a bag is deployed in front of an occupant seated in a driver's seat, but also a front and side of a passenger seat provided on the side of the driver's seat. A so-called passenger airbag device, a side-impact airbag device, and the like, in which the bag body is deployed by the user, have been devised.

[0003] For example, an airbag device for a passenger seat is generally provided on an instrument panel (dashboard) in front of a passenger seat. Depending on the distance between the occupant and the instrument panel, it may be better not to operate the airbag device.

Here, as a method of determining whether or not to operate the airbag device, a sensor having a transmitting / receiving antenna and a processing means in front of an occupant of a vehicle (hereinafter referred to as a radio sensor) is used. There is a method of detecting the distance between the occupant and the airbag device, and determining whether or not the airbag device is ready to be operated based on the detection result.

Hereinafter, a conventional radio wave sensor will be briefly described with reference to FIG.

In the radio wave sensor 100, the processing means 106
The radio wave generated by the radio wave supply unit 108 based on the radio wave supply signal is transmitted (emitted) from the transmission antenna 102 and received by the reception antenna 104.

At this time, an electric field is formed between the transmitting antenna 102 and the receiving antenna 104, and a predetermined range of the electric field is set as a detection range of the radio wave sensor 100. When the occupant approaches this detection range, the coupling coefficient between the transmitting antenna 102 and the receiving antenna 104 (hereinafter, referred to as an unknown coupling coefficient) is reduced according to the proximity distance, and the amplitude of the received radio wave is reduced.

The radio wave received by the receiving antenna 104 is transmitted to the signal converter 110 of the processing means 106, and the signal converter 110 detects a difference between the amplitude of the received radio wave and the amplitude proportional to the above-mentioned radio wave supply signal. At the same time, it is converted to a DC analog signal and output. This DC analog signal becomes a signal corresponding to the distance of the occupant to the transmitting antenna 102 and the receiving antenna 104 (hereinafter, referred to as a detection signal). Based on the detection signal, for example, the distance between the occupant and the airbag device is detected. It can be seen from the above that the detection signal is a function using the unknown coupling coefficient as a parameter.

[0009] The temperature inside the vehicle in which the radio wave sensor is installed is not constant. When the temperature inside the vehicle changes,
Along with this, the circuit characteristics of the radio wave supply unit 108 having temperature dependency also change, and the radio wave supply signal changes. Further, the radio wave supply signal also changes due to aging of the circuit constituting the radio wave supply unit 108.

For this reason, considering the temperature change of the vehicle,
The above detection signal is a function using the radio wave supply signal as a parameter in addition to the unknown coupling coefficient, and the detection signal does not directly correspond to the distance of the occupant to the transmission antenna 102 and the reception antenna 104 (the radio wave supply signal Errors due to changes).

Here, the radio wave sensor 100 uses a low frequency (about 40 KHz) radio wave without directivity.
The coupling ratio is low (approximately −60 dB), and the distance between the occupant and the airbag device is detected based on a minute change in the amplitude of the received radio wave. Therefore, the error that the change in the radio wave supply signal due to the temperature change in an assumed range in the vehicle affects the detection signal cannot be ignored. In particular, when the temperature change with respect to the predetermined reference temperature is large, an unacceptable detection error may occur.

In order to prevent such an error from occurring, it is conceivable to add a temperature compensating device such as a temperature compensating sensor. However, there is a problem that the radio wave sensor system as a whole becomes complicated and expensive. was there.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide an occupant detection system capable of accurately detecting the distance between an occupant and an airbag device with a simple structure in consideration of the above fact.

[0014]

An occupant detection system according to the present invention is disposed near a seat in a vehicle,
A transmitting antenna capable of transmitting radio waves toward the seat, a receiving antenna disposed near the seat and capable of receiving the radio waves, and electrically connectable to the transmitting antenna and the receiving antenna, respectively; It is possible to supply a radio wave based on a predetermined radio wave supply signal to the antenna and to detect the amplitude of the radio wave received by the receiving antenna,
And a processing means capable of detecting the distance of the occupant to a predetermined position based on the detection result of the amplitude of the received radio wave. A pair of correction antennas having coefficients, the transmission antenna and the reception antenna, and the correction antenna and the processing means are electrically connected to the connection state between the transmission antenna and the reception antenna and the processing means, And a switching unit that can switch a connection state between the correction antenna and the processing unit, and a switching unit that is electrically connected to the processing unit, the processing unit when the correction antenna is connected to the processing unit. While obtaining correction data corresponding to the change of the radio wave supply signal based on the detection result, the transmitting antenna and the Is characterized in that signal antenna is and a correcting means for correcting the detection result of said processing means when connected to said processing means.

In the occupant detection system according to the first aspect, first, the switching means is operated, and the correction antenna and the processing means are connected. When the correction antenna and the processing unit are connected, a radio wave generated based on the radio wave supply signal is supplied from the processing unit to the correction antenna. This radio wave is attenuated according to a predetermined coupling coefficient of the correction antenna, and is transmitted again to the processing means.

When the radio wave is transmitted, the processing means detects a difference between the amplitude of the transmitted received radio wave and an amplitude proportional to the radio wave supply signal.

Further, the difference data is output to the correction means, and stored as correction data in the correction means.

Next, the switching means is switched, and the transmitting antenna and the receiving antenna are connected to the processing means. When the transmitting antenna and the receiving antenna are connected to the processing means,
A radio wave based on the radio wave supply signal is supplied from the processing means to the transmission antenna, and the radio wave is transmitted (radiated) from the transmission antenna to a seat in the vehicle and received by the reception antenna. At this time, an electric field is formed between the transmitting and receiving antennas.

When no occupant exists in a predetermined range (detection range) of the electric field, the radio wave is attenuated by a predetermined coupling coefficient (permittivity) between the transmitting and receiving antennas and is received by the receiving antenna. Here, basically, the above-mentioned radio wave supply signal is set based on the reception amplitude at this time, and is stored in the processing means. On the other hand, an occupant (dielectric)
Approach, the coupling coefficient between the transmitting and receiving antennas decreases,
The amplitude of the radio wave is further attenuated and received by the receiving antenna.

The radio wave received by the receiving antenna is transmitted to the processing means, and the processing means detects a difference between the amplitude of the received radio wave and an amplitude proportional to the radio wave supply signal. Further, this difference data (detected value) is output to the correction means,
Correction is performed by the correction means using the correction data.

Here, the correction data is a value directly corresponding to the radio wave supply signal, since the coupling coefficient of the correction antenna is always constant. On the other hand, the detection value is a function using the radio wave supply signal and the unknown coupling coefficient between the transmission and reception antennas as parameters as described in the related art, and when the radio wave supply signal is constant (known), the transmission and reception antenna Is a value directly corresponding to the distance of the occupant with respect to (hereinafter referred to as distance data). However, when the radio wave supply signal changes due to the temperature characteristics of the circuit or the like, the detected value does not become a value directly corresponding to the distance data. Therefore, it is necessary to correct the detection value with correction data corresponding to the radio wave supply signal,
The distance data is obtained by the correction.

As a result, the correcting means can obtain the distance data with high accuracy by eliminating the influence of the change in the radio wave supply signal due to the temperature change in the vehicle and the aging deterioration. That is, the distance of the occupant to the transmitting / receiving antenna is detected.

Therefore, for example, in a configuration in which the detection result by the correction means is output to the airbag device, when the occupant and the transmitting / receiving antenna (airbag device) are closer than a predetermined distance, the operation of the airbag device is prohibited. be able to.

As described above, in the occupant detection system according to the first aspect, the distance between the occupant and the airbag device can be accurately detected with a simple configuration while eliminating the influence of a temperature change in the vehicle.

An occupant detection system according to a second aspect of the present invention is the occupant detection system according to the first aspect, wherein the correction antenna is formed on a printed circuit board.

In the occupant detection system according to the second aspect, since the correction antenna is formed on the printed circuit board, the size of the correction antenna can be reduced. In particular, if the correction antenna is arranged on the substrate of the circuit constituting the processing means, the switching means can be arranged on the same substrate, so that the occupant detection system as a whole has a smaller and lighter configuration, which is more effective.

As described above, in the occupant detection system according to the second aspect, the distance between the occupant and the airbag device can be accurately detected with a simpler configuration.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a side sectional view of a part of a vehicle 50 to which an occupant detection system 10 according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing a schematic configuration of the occupant detection system 10 and the passenger airbag device 40. FIG. 3 is a perspective view showing a part of the vehicle 50.

As shown in FIG. 1, an occupant detection system 10 applied to a vehicle 50 is disposed near an airbag device 40 for a passenger seat provided on an instrument panel 52 of the vehicle 50 and seated on a passenger seat 54. The configuration is such that the state of approach of the occupant 60 to the passenger seat airbag device 40 is detected.

Here, the occupant detection system 10 includes a transmission antenna 12 and a reception antenna 14 for transmitting and receiving radio waves. The transmitting antenna 12 and the receiving antenna 14
Both are formed in a flat plate shape, and are installed on the inner surface of a cover of a passenger airbag device 40 described later.

Further, the occupant detection system 10 includes a correction antenna 22 in a processing circuit section 20 including a configuration as processing means. The correction antenna 22 is integrally formed on a printed circuit board (not shown) for transmission and reception, and has a predetermined coupling coefficient. It should be noted that the coupling coefficient of the correction antenna 22 does not change in the temperature change range assumed in the vehicle 50.

As shown in FIG. 2, the transmitting antenna 12 is electrically connected to the terminal 24A of the changeover switch 24 constituting the switching means provided in the processing circuit section 20, and the receiving antenna 14 is electrically connected to the terminal 24B of the changeover switch 24. It is connected to the. The correction antenna 22 is electrically connected to a terminal 24C and a terminal 24D of the changeover switch 24 at the transmission / reception end.

Further, the changeover switch 24 has a terminal 24E.
The terminal 24 is connected to the radio wave supply unit 26 of the processing circuit unit 20 at
At F, they are electrically connected to the signal conversion unit 28 of the processing circuit unit 20, respectively.

Here, the changeover switch 24 is connected to a terminal 24A.
And the terminal 24E and the terminal 24B and the terminal 24F are simultaneously connected, and by switching, the terminal 24C and the terminal 24E and the terminal 24D and the terminal 24F are simultaneously connected.

Accordingly, the changeover switch 24 operates in a state where the radio wave supply unit 26 and the transmission antenna 12 and the reception antenna 14 and the signal conversion unit 28 are connected (a state where the transmission / reception antennas 12 and 14 are selected), and A state in which the supply unit 26 is connected to the signal conversion unit 28 via the correction antenna 22 (a state in which the correction antenna 22 is selected).
Each of the states can be switched. The changeover switch 24 is electrically connected to a correction computer 30 described later, and is configured to switch between connection states according to a command from the correction computer 30.

The radio wave supply unit 26 of the processing circuit unit 20
Is configured to generate a radio wave of approximately 42 KHz based on the radio wave supply signal and transmit the generated radio wave to the transmission antenna 12 or the correction antenna 22. The radio wave supply signal is transmitted to the vehicle 50
Temperature is the reference temperature (for example, 20 ° C.) and the passenger seat 5
4 is set based on radio waves received by the receiving antenna 14 when the occupant 60 is not on the vehicle 4 and stored in the radio wave supply unit 26.

On the other hand, the signal conversion section 28 of the processing circuit section 20
Detects the difference between the amplitude of the radio wave transmitted from the receiving antenna 14 or the correction antenna 22 and the amplitude proportional to the radio wave supply signal, and converts the difference into a DC analog signal.

The signal converter 28 is electrically connected to the correction computer 30 and is configured to output the correction data and the detected value to the correction computer 30 every time the changeover switch 24 is switched.

As described above, the correction computer 30 includes the changeover switch 24 and the signal conversion unit 28 in the processing circuit unit 20.
Is electrically connected to The correction computer 2
8 has a storage device (ROM) not shown. The ROM includes a switching program for selecting the correction antenna 22 at the time of startup and then outputting a switching signal for appropriately switching the antenna connection state to the changeover switch 24, and when the correction antenna 22 is selected by the changeover switch 24. The DC analog signal input from the signal conversion unit 28 is stored as correction data, and the transmission / reception antennas 12 and 1 are stored.
4 is selected, the DC analog signal input from the signal conversion unit 28 is used as a detection value, and a correction program for correcting the detection value with correction data. An occupant detection program for operating the processing circuit unit 20 is stored. Further, the correction computer 28 includes a CPU (not shown) for executing each of the programs.

The correction computer 30 is electrically connected to the airbag computer 42 and outputs a correction result to the airbag computer 42.

The processing circuit unit 20 and the correction computer 30 are arranged at appropriate positions on the vehicle 50.

The airbag computer 42 constitutes a part of the passenger seat airbag device 40 and is electrically connected to an activation device 46 provided in the passenger seat airbag device 40. In addition, the airbag computer 42
It is also electrically connected to a sensor 44 provided in the passenger seat airbag device 40. The sensor 44 transmits a detection signal to the airbag computer 42 when detecting a deceleration or a load that is equal to or more than a predetermined value, and basically the airbag computer that receives the detection signal from the sensor 44. Reference numeral 42 activates an activation device 46.

As shown in FIGS. 1 and 3, the passenger airbag device 40 is provided in the instrument panel 52 in front of the passenger seat 54, and the airbag computer 42 is provided with the passenger airbag device. It is arranged at an appropriate position near 40.

Activation device 4 for passenger airbag device 40
Numeral 6 includes an ignition device 48 for igniting the igniting agent, and both of them are provided in an inflator (not shown).
As a result, the ignition device 48 ignites the igniting agent, so that the gas generating agent also stored in the inflator burns,
A large amount of gas is generated instantaneously. At a predetermined position near the inflator of the passenger seat airbag device 40, a bag (not shown) is disposed in a folded state,
The inflator is inflated by the pressure of the gas generated by each inflator and is deployed at a predetermined position in front of the occupant.

Next, the operation of the present embodiment will be described.

The occupant detection system 10 according to the present embodiment
For example, when the ignition key is inserted into the key cylinder and an accessory (for example, audio or power window) of the vehicle 50 is operable or the engine is started, the correction computer 30 is activated to start the correction computer. The occupant detection program stored in advance in 30 is activated.

The correction computer 30 in which the occupant detection program has been activated first operates the changeover switch 24 and the processing circuit section 20.

When the changeover switch 24 and the processing circuit section 20 are operated, the changeover switch 24 changes the correction antenna 22, the radio wave supply section 26 and the signal conversion section 28 based on the changeover signal input from the changeover program of the correction computer 30.
And is connected. When the correction antenna 22 is selected, the radio wave having a frequency of about 42 KHz generated based on the radio wave supply signal by the radio wave supply unit 26 is attenuated according to the constant coupling coefficient of the correction antenna 22 at all times. The data is output to the conversion unit 28.

When a radio wave is input, the signal converter 28 detects a difference between the amplitude of the radio wave and an amplitude proportional to the radio wave supply signal, and converts the difference data into a DC analog signal. This DC analog signal is output to the correction computer 30.

When the DC analog signal is input, the correction computer 30 stores the value indicated by the DC analog signal as correction data by the correction program.

When the correction data is stored in the correction computer 30, the changeover switch 24 is switched based on the switching signal input from the switching program of the correction computer 30, and the transmitting and receiving antennas 12 and 14 are selected. . When the transmission antenna 12 is connected to the radio wave supply unit 26, a radio wave having a frequency of approximately 42 KHz generated by the radio wave supply unit 26 is transmitted to the transmission antenna 12. When this radio wave is transmitted, the radio wave is transmitted (radiated) from the transmission antenna 12 and received by the reception antenna 14.

At this time, an electric field is formed between the transmitting antenna 12 and the receiving antenna 14, and a predetermined range of the electric field is set as shown in a region A of FIG.
Is the detection range.

Here, when the occupant 60 does not exist in the detection range, a radio wave attenuated according to a predetermined coupling coefficient between the transmitting and receiving antennas 12 and 14 is received by the receiving antenna. On the other hand, when the occupant 60 (dielectric) approaches the detection range, the coupling coefficient between the transmitting and receiving antennas 12 and 14 decreases, so that the radio wave whose amplitude is further reduced is received by the receiving antenna 14.
Is received by

The radio wave received by the receiving antenna 14 is transmitted to the signal converter 26. When the received radio wave is transmitted,
The signal converter 26 detects a difference between the received radio wave amplitude and the amplitude proportional to the radio wave supply signal, and converts the difference data into a DC analog signal. Further, this DC analog signal is output to the correction computer 30 as a detection value.

When the detection value is input, the correction computer 30 corrects the detection value by the correction data using the correction data.

Incidentally, the temperature inside the vehicle 50 changes due to changes in the outside air temperature, heat generated by the engine and the like, operation of the air conditioner, and the like. When the temperature inside the vehicle 50 changes, the characteristics of the circuit forming the radio wave supply unit 26 have temperature dependence, so that the characteristics of the radio wave supply unit 26 change and the radio wave supply signal changes. For this reason, when the temperature inside the vehicle 50 changes,
The detected value does not directly correspond to the distance between the transmitting and receiving antennas 12, 14 and the occupant 60. The radio wave supply unit 26
The radio wave supply signal also changes due to the aging deterioration of the circuit that constitutes, and the detected value does not directly correspond to the distance between the transmitting and receiving antennas 12 and 14 and the occupant 60.

Here, the correction data has a value directly corresponding to the radio wave supply signal, since the coupling coefficient of the correction antenna 22 is always constant. On the other hand, the above detection value is
This is a function using the radio wave supply signal and the unknown coupling coefficient between the transmitting and receiving antennas 12 and 14 as parameters. When the radio wave supplying signal is constant (known), a value directly corresponding to the distance of the occupant 60 to the transmitting and receiving antennas 12 and 14. (Hereinafter referred to as distance data).

Therefore, if the detection value is corrected using the correction data, the distance data can be obtained. Here, since the transmitting and receiving antennas 12 and 14 are both arranged on the inner surface of the cover of the passenger airbag device 40, the distance data corresponds to the distance between the passenger airbag device 40 and the occupant 60. Therefore, by obtaining the distance data, the distance of the occupant 60 to the passenger airbag device 40 is detected.

Since the temperature change in the vehicle 50 is sufficiently slow with respect to the switching time between the correction antenna 22 and the transmitting / receiving antennas 12 and 14, it is not necessary to consider the influence of the antenna switching time.

As described above, the correction computer 30 accurately detects the distance of the occupant 60 from the passenger seat airbag device 40 by eliminating the influence of the change in the radio wave supply signal due to the temperature change and the aging deterioration in the vehicle 50. it can.

When the correction is performed by the correction computer 30, the correction result (distance data) is output to the airbag computer 42. In the airbag computer 42, based on the above correction result, when the occupant 60 is closer to the passenger airbag device 40 than a predetermined distance, the passenger airbag device 40 is disabled. . On the other hand, when the occupant 60 is separated from the passenger airbag device 40 by a predetermined distance, the operable state of the passenger airbag device 40 is maintained.

Further, when the correction computer 30 is activated, the above series of operations are repeatedly performed.
The distance of the occupant 60 to the passenger seat airbag device 40 is constantly detected.

In the present embodiment, the occupant detection system 10 is applied to the passenger airbag device 40. However, the present invention is not limited to this. For example, the driver airbag device or the side collision airbag device may be used. It may be applied to a device or the like. Further, the occupant detection system may be applied to a part or all of the driver seat, the passenger seat, and the rear seat of the vehicle 50 at the same time.

In this embodiment, the transmitting antenna 1
2 and the receiving antenna 14 are connected to the passenger seat airbag device 40.
However, the present invention is not limited to this. For example, the cover may be disposed at an appropriate position on the outer or inner surface of the cover, at an appropriate position on the inner or outer surface of the instrument panel 52, on a ceiling, in a seat back, or on a door. Is also good. Further, a configuration having a plurality of pairs of transmission / reception antennas may be employed. For example, a pair of transmission / reception antennas may be provided on the instrument panel 52 and the door to determine whether or not the passenger airbag device 40 and the side collision airbag device can operate. It is good also as a structure which can be determined simultaneously.

Furthermore, in the present embodiment, the switching frequency between the correction antenna 22 and the transmitting / receiving antennas 12 and 14 is made equal. However, the present invention is not limited to this. The frequency may be one hundredth of the frequency of connection to the transmitting and receiving antennas 12 and 14, and the connection timing of the correction antenna 22 may be controlled by time (for example, once every five minutes). Further, in the present embodiment, the switching between the correction antenna 22 and the transmission / reception antennas 12 and 14 is controlled by the correction computer 30, but the present invention is not limited to this.
A configuration in which switching is performed by an oscillation circuit or the like may be employed.

As described above, in the occupant detection system 10 according to the present embodiment, the occupant 60 and the passenger airbag device 40 can be easily connected to each other by eliminating the influence of a temperature change or the like in the vehicle 50 with a simple configuration. Can be accurately detected.

[0068]

As described above, the occupant detection system according to the present invention can accurately detect the distance between the occupant and the airbag device with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a part of a vehicle to which an occupant detection system according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a schematic circuit configuration of an occupant detection system and an airbag device according to an embodiment of the present invention.

FIG. 3 is a perspective view showing the interior of a vehicle to which the occupant detection system according to the embodiment of the present invention is applied.

FIG. 4 is a block diagram showing a configuration of a conventional radio wave sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Occupant detection system 12 Transmission antenna 14 Receiving antenna 20 Processing circuit part (processing means) 22 Correction antenna 24 Changeover switch (switching means) 30 Correction computer (correction means) 40 Passenger-seat airbag device 42 Airbag computer 50 Vehicle 60 Crew

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D054 AA02 AA03 AA13 AA14 EE10 EE11 EE25 FF16 5J070 AC02 AD02 AE09 AF03 AH40 AK22

Claims (2)

[Claims] A transmitting antenna disposed near a seat in the vehicle and capable of transmitting radio waves toward the seat; a receiving antenna disposed near the seat and capable of receiving the radio wave; Each of the antennas can be electrically connected to the receiving antenna, and can supply a radio wave based on a predetermined radio wave supply signal to the transmitting antenna, and can detect the amplitude of the radio wave received by the receiving antenna, and A processing means capable of detecting a distance of the occupant to a predetermined position based on the detection result, wherein a pair of corrections which are electrically connectable to the processing means and have a constant coupling coefficient at all times An antenna for transmission, the transmission antenna and the reception antenna, the correction antenna and the processing means, And a switching unit that can switch a connection state between the reception antenna and the processing unit, and a connection state between the correction antenna and the processing unit, and a correction unit that is electrically connected to the processing unit, While obtaining correction data corresponding to the change in the radio wave supply signal based on the detection result of the processing means when connected to the processing means, the transmitting antenna and the receiving antenna are An occupant detection system, comprising: a correction unit configured to correct a detection result of the processing unit when connected to the processing unit. 2. The occupant detection system according to claim 1, wherein the correction antenna is formed on a printed circuit board.