JP3393195B2 - Object detection device and 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 object detection device and an occupant detection system, and in particular, it is possible to deploy an airbag of an airbag device in accordance with the occupant's seating condition in the passenger seat of an automobile equipped with the airbag device. The present invention relates to an improvement of an occupant detection system that can be set to a state or an undeployable state.

[0002]

2. Description of the Related Art Generally, an airbag device is a device for 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 has a safing sensor SS1, a squib SQ1, and a squib SQ1, as shown in FIG.
Switching element SW1 such as field effect transistor
Driver side squib circuit consisting of a series circuit, a safing sensor SS2, a squib SQ2, a switching element SW2 such as a field effect transistor, and a passenger side squib circuit, and an electronic acceleration sensor (collision detection sensor) GS. And the presence or absence of a collision based on the output signal of the electronic acceleration sensor GS, and the switching element SW1,
The control circuit CC has a function of supplying a signal to the gate of SW2.

According to this airbag device, when the vehicle 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 seat side becomes operable. Then, when the control circuit CC determines that the vehicle has surely collided based on the signal from the electronic acceleration sensor GS, the switching element S
A signal is supplied to the gates of W1 and SW2, and the switching elements SW1 and SW2 are turned on. by this,
As a result of the current flowing through each squib circuit, the airbags on the driver's seat side and the passenger's seat side are deployed based on the heat generation of the squibs SQ1 and SQ2, and the occupants are protected from the impact due to the collision.

By the way, since the airbag apparatus is constructed so that the airbag is deployed 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.

Therefore, conventionally, in order to address such a problem, an airbag device as shown in FIG. 10, 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, a weight sensor is used, and whether an adult or a child is determined based on the weight of the occupant measured by the weight sensor, and an image of the occupant seated in the seat taken by the camera It has been proposed that the processing determines whether the child 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.

Further, according to the latter method, although the occupant's seating condition and whether the occupant is an adult or a child can be judged fairly accurately, the image pickup data photographed by the camera is image-processed and compared with various patterns. There is a problem that the processing device becomes complicated and expensive because the judgment must be made.

[0009]

Therefore, the applicant of the present invention is
Previously, the occupant detection system shown in FIG. 11 was proposed. This occupant detection system is basically a weak electric field (Electric) generated in an antenna electrode arranged on a seat.
The disturbance of Field) is used. First, Fig. 1
As shown in FIG. 1 (a), the oscillation circuit OS is attached to the antenna electrode E.
By applying a high frequency low voltage from C, a weak electric field is generated around the antenna electrode E, and as a result, a current I flows on the antenna electrode E side. In this state, FIG.
As shown in (b), the object OB is placed near the antenna electrode E.
Is present, the electric field is disturbed, and a current I1 different from the current I flows on the antenna electrode E side.

Therefore, the antenna electrode E is used depending on whether the object OB is on the car seat or not.
The current flowing to the side of the vehicle changes, and by utilizing this phenomenon, the seating status of the occupant in the seat can be detected. In particular, by increasing the number of antenna electrodes, it becomes possible to obtain much information about objects on the seat, including occupants,
It is possible to more accurately detect the seating status of the occupant in the seat. The current flowing to the antenna electrode E side increases when the object OB is on the sheet, and the current flowing to the antenna electrode E side decreases when the object OB is not on the sheet.

Next, an occupant detection system according to the prior art utilizing this principle will be described with reference to FIGS. 12 to 13 show an arrangement configuration of a passenger seat (or a driver's seat) and an antenna electrode, and the seat 1 mainly includes a seating portion 1a and a backrest portion 1b.
It consists of and. The seating portion 1a includes, for example, a seat frame 3 fixed to a base 2 that can slide back and forth.
And a cushioning material arranged on the upper part of the seat frame 3 and an exterior material covering the cushioning material,
The backrest portion 1b is also made up of a seat frame, a cushion material, an exterior material, and the like, similar to the seating portion 1a.
In particular, a plurality of antenna electrodes 4 (4a to 4d) formed in substantially the same shape (for example, a rectangular shape) are symmetrically arranged in the seating portion 1a so as to be spaced apart from each other, but are arranged in the backrest portion 1b. Alternatively, they can be arranged in both. still,
A control unit 10, which will be described later, is incorporated in the seat 1, and is arranged, for example, in the seat frame 3 or in the vicinity thereof.

As shown in FIG. 13, for example, the antenna electrode 4 is basically symmetrical with a base member 5 made of an insulating member such as a nonwoven fabric and one surface of the base member 5 spaced apart from each other. It is composed of the arranged antenna electrode portions 4a to 4d having conductivity, and is arranged inside the exterior material of the seating portion 1a. In particular, the antenna electrode part 4
Although a to 4d are made of, for example, a conductive cloth, thread-like metal wires or conductive fibers are woven into the base member 5, or the seat cloth surface of the seating portion 1a is regarded as the base member. Then, it can be woven into this or coated with conductive paint on the cloth surface. Further, lead wires 6 (6a to 6d) such as shield wires are electrically connected to desired portions of the antenna electrode portions 4a to 4d,
Lead-out ends of the lead wires 6a to 6d are control units 1 to be described later.
0 connectors 14a to 14d.

As shown in FIG. 14, the control unit 10 incorporated in the above-mentioned sheet 1 outputs an electric field of a sine wave and generates an electric field around the antenna electrode portions 4a to 4d. (Oscillation circuit) 11, an antenna electrode part 4a having a resistor 12 connected to the transmission system of the transmission signal output from the electric field generating means 11, and a plurality of switching means 13a to 13d connected to the output side of the resistor 12. 4d, a switching circuit 13 connected to the switching means 13a to 13d of the switching circuit 13 at the time of closing operation, and connectors 14a to 14d arranged in the housing of the control unit 10, and an output side of the resistor 12, An AC-DC conversion circuit 15 for converting an AC line voltage related to a current flowing through the antenna electrode 4 into a DC voltage, CPU, A
/ D converter, external memory (eg EEPROM, RA
M) and the like, and a connector 19 arranged in the housing and connected to a battery power source (not shown).
And a power supply circuit 20 connected to the connector 19. These components are housed in the same housing to form the control unit 10, and are fixed to, for example, the seat frame 3 in the seating portion 1a of the seat 1 so as not to be exposed to the occupant's seating side. To the control circuit 18 of the control unit 10, for example, an airbag device 30 having the configuration shown in FIG. 16 is connected. The selective switching of the switching means 13a to 13d in the switching circuit 13 is performed based on the signal from the control circuit 18.

In the control unit 10 described above, the electric field generating means 11 is composed of, for example, a quadrature oscillation circuit, and outputs a high frequency low voltage of a sine wave.
As the oscillation circuit, an appropriate oscillation circuit such as a Wien bridge oscillation circuit can be used in addition to the quadrature oscillation circuit. In the output of the electric field generating means 11, its frequency is, for example, about 120 KHz, and the voltage is, for example, 5 VP-
Although it is P, it can be changed to an appropriate value.

In the control unit 10, the AC-D
The C conversion circuit 15 is composed of a full-wave rectifier circuit 16 and a smoothing circuit 17, as shown in FIG. 15, for example. The full-wave rectifier circuit 16 includes first and second operational amplifiers 16a.
1, 16a2 and the first and second diodes 16b1, 1
6b2 and resistors 16c1 to 16c3. The smoothing circuit 17 includes a resistor 17a and a capacitor 17b. The AC-DC conversion circuit 15
A control circuit 18 is connected to the output side of the.

Further, in the control unit 10, the power supply circuit 20 is configured to step down the battery power supply (12V) to, for example, 5V to generate a single Vcc power supply, and is configured by, for example, a three-terminal regulator. There is. The single Vcc power source generated by the power source circuit 20 is supplied to all the constituent elements of the control unit 10 that require the power source. This Vc
Although it is desirable that the c-power supply be unified, it is also possible to set different voltages.

Next, the operation of the occupant detection system thus constructed will be described with reference to FIGS. First, when the electric field generating means 11 in FIG.
A high frequency low voltage of a sine wave as shown in (a) is output. This high-frequency output is the resistance 12, the transmission system, and the switching circuit 13.
(Switching means 13a to 13d), connector 14a
Is supplied to the antenna electrodes 4 (4a to 4d) via the electrodes 14a to 14d, and as a result, a weak electric field is generated around the antenna electrodes 4 (4a to 4d). At this time, the switching circuit 13 is controlled to be opened and closed by a signal from the control circuit 18, only the switching means 13a is first closed, then only the switching means 13b is closed, and so on. The switching control is performed such that only the switching means of 1 is closed and the other switching means are opened at the same time. Therefore, the specific switching means (13a-1
When 3d) is closed, the high frequency output is a resistor 12,
Transmission system (transmission line), specific switching means (13
a to 13d), and supplied to the specific antenna electrodes 4 (4a to 4d) via specific connectors (14a to 14d),
As a result, a weak electric field is generated around the specific antenna electrode 4 (4a to 4d), depending on whether or not the occupant is seated on the seat 1, the occupant's identification (discrimination between adult and child), and the like. Different levels of current flow.

For example, when an occupant is seated on the seat 1, a large capacitance component is present around the specific antenna electrode as compared with the stray capacitance in the empty seat state, and a high level current is generated. Since it flows, the voltage drop across the resistor 12 also increases. For this,
Since the capacitance component of the occupant is larger in adults than in children, the level of the current flowing through the antenna electrode is also high and the voltage drop across the resistor 12 is also high. Therefore, the line voltage of the transmission system becomes as shown in FIG. 17 (a), and the line voltage V has different capacitance components between the adult and the child, and the current flowing through the antenna electrode is different. Is smaller and larger in children. On the other hand, in the vacant state where the passenger is not seated on the seat 1, a low level current flows based on the stray capacitance existing around the specific antenna electrode, but the voltage drop in the resistor 12 is extremely small. Therefore, the line voltage V becomes a value close to the output voltage of the electric field generating means 11.

Thus, the AC line voltage on the output side of the resistor 12 is taken into the AC-DC conversion circuit 15. First, the AC line voltage is converted into the full-wave rectification circuit 16
17B, full-wave rectification is performed as shown in FIG. 17B, and then the smoothing circuit 17 converts it into direct current (Vd) as shown in FIG. 17C. Specifically, when a positive half-cycle voltage of the AC line voltage is input to the full-wave rectifier circuit 16, the output side of the first operational amplifier 16a1 is inverted to the negative side, and the second diode 16b2 is turned on. Because of the cut-off state, the positive half-cycle voltage applied to the second operational amplifier 16a2 via the resistor 16c2 is output to the output side of the second operational amplifier 16a2. next,
When the voltage of the negative half cycle is input to the full-wave rectification circuit 16, the output side of the first operational amplifier 16a1 is inverted to positive, and the second diode 16b2 is turned on. Therefore, the second operational amplifier 16a2 is turned on. The voltage of the inverted state is output to the output side of. Therefore, as the output of the full-wave rectifier circuit 16, an output voltage as shown in FIG. 17B is obtained.

As described above, the level of the DC output Vd of the AC-DC converting circuit 15 differs depending on the output of the full-wave rectifying circuit 16. In FIG. 17 (c), the dotted line indicates the DC conversion level when the passenger is seated, and the solid line indicates the DC conversion level when the passenger is seated. There is a discernible level difference between the two. ing. This DC conversion level is
If the resistance value of the resistor 12 in the transmission system is set to be constant,
It depends on the size of the capacitance component existing around the antenna electrodes 4 (4a to 4d), and becomes small when the capacitance is large like an adult, and is large when the capacitance is small like a child. Becomes
It becomes the largest when the seat 1 is empty. This A
The DC output of the C-DC conversion circuit 15 is sequentially taken into the control circuit 18, A / D converted, and stored in the memory.

The control circuit 18 previously stores, for example, a threshold value (threshold value data) relating to the seating status of the occupant seated on the seat 1 (whether seated or not, identification of adult or child, etc.). Has been done. Specifically, the threshold value regarding whether or not a passenger is seated is set as follows. For example, as shown in FIGS. 18 (a) and 18 (b), when an adult occupant P and a child occupant SP are seated in the seat 1, they face the respective antenna electrodes 4 (4a to 4d). Due to the difference in area and the like, there is a difference in the capacitance component existing around each antenna electrode 4 (4a to 4d). As a result, the antenna electrodes 4 (4a-4
The level of the current flowing in d) is different, the current level is higher in the case of the adult occupant P than in the case of the child occupant SP, and the amount of voltage drop at the resistor 12 is also different.
The DC level output from the conversion circuit 15 also becomes a different level. Therefore, the level between the DC output related to the current level in the case of the child SP and the DC output in the vacant state shown by the dotted line in FIG. 17C is set as the threshold value regarding whether or not the occupant is seated. If the DC output data is smaller than this threshold value, it is determined that the occupant is seated, and if the DC output data is large, it is determined that the occupant is not seated. In particular,
This threshold value is preferably set for the total sum of the DC output from the AC-DC conversion circuit 15 related to the current flowing through each antenna electrode, but can be set for each antenna electrode.

The threshold value for identifying the occupant is set as follows. For example, as shown in FIG. 18 (a), when an adult occupant P is seated on the seat 1, the level of the current flowing through each antenna electrode 4 (4 a to 4 d) increases, and the resistance 12 causes The line voltage of the transmission system decreases due to the voltage drop, and the DC level output from the AC-DC conversion circuit 15 becomes the level (Vd) shown by the solid line in FIG. 17C. On the other hand, as shown in FIG.
When the child occupant SP is seated in the seat 1, the level of the current flowing through each antenna electrode becomes small, and the line voltage of the transmission system becomes small due to the voltage drop at the resistor 12, and the AC-DC conversion circuit. The DC level output from 15 is between the levels shown by the solid line and the dotted line in FIG. 17 (c). Therefore, the DC output related to the intermediate current level between the adult occupant P and the child occupant SP is set as the threshold value for identification. If the DC conversion data is smaller than this threshold value, it is determined to be an adult passenger P, and if it is large, it is determined to be a child passenger SP. In particular, this threshold value is preferably set with respect to the total sum of the DC output from the AC-DC conversion circuit 15 related to the current flowing through each antenna electrode, but it can also be set for each antenna electrode. .

Therefore, the signal data relating to the occupant's seating status and the like fetched by the control circuit 18 is previously stored in the control circuit 1.
18 is compared with the threshold value data regarding the seating condition of the occupant stored in FIG. 8 and, for example, as shown in FIG. 18A, AC is associated with the high current levels of all the antenna electrode portions 4a to 4d. If the direct current output from the -DC conversion circuit 15 is low and lower than the threshold value for seat identification, the occupant seated in the seat 1 is an adult occupant P.
Is determined. As a result, the airbag device 30 shown in FIG. 16 is set so that the airbag can be deployed by the transmission signal from the control circuit 18. On the contrary, as shown in FIG. 18B, AC- is associated with the low current levels of all the antenna electrode portions 4a to 4d.
When the DC output from the DC conversion circuit 15 is high and higher than the threshold value for seat identification, the occupant seated in the seat 1 is determined to be the child SP. As a result, the airbag device 30 shown in FIG. 16 is set by the transmission signal from the control circuit 18 so that the airbag cannot be deployed. That is, the transmission signal from the control circuit 18 is input to the control circuit CC of the airbag device 30, and in the latter case, it is set so as not to supply the gate signal to the switching element SW2 on the passenger side when the vehicle collides. A gate signal is supplied to the switching element SW1 on the driver's seat side. In the former case, the gate signals are set to be supplied to the switching elements SW1 and SW2.

As described above, according to the prior art, the antenna electrode 4 (4a ...
In 4d), a current corresponding to the capacitance component existing around the antenna electrode flows, and at this time, a voltage drop occurs in the resistor 12 connected to the transmission system according to the current, and the line voltage of the transmission system is The voltage is related to the current flowing through the antenna electrode. In particular, the current flowing through the antenna electrode differs depending on whether or not the seat 1 is seated and whether or not the occupant is an adult. Therefore, by converting this voltage from AC to DC by the AC-DC conversion circuit 15, identification is performed. Possible DC data is obtained. This DC data can be taken into the control circuit 18, and the seating status of the occupant in the seat 1 and the like can be appropriately determined based on the signal data relating to the DC data. Therefore, the main problem in the conventional example shown in FIG. 10 can be solved.

In addition, the control circuit 18 determines the seating status of the occupant on the seat 1 based on the signal data relating to the direct current output from the AC-DC conversion circuit 15, and the determination result is communicated to the airbag device 30 by the communication means. The air bag device can be appropriately controlled according to the seating condition of the occupant.

However, in the prior art, AC-
The full-wave rectification circuit 16 in the DC conversion circuit 15 is shown in FIG.
As shown in, for example, the first and second operational amplifiers 16a1,
16a2, first and second diodes 16b1 and 16b
2, the resistors 16c1 to 16c3 are used, but the forward voltage of the first and second diodes 16b1 and 16b2 has a negative temperature coefficient, so that the forward voltage also changes depending on the ambient temperature. For this reason, the output voltage of the full-wave rectifier circuit 16 changes in the voltage corresponding to the cycle that is inverted by the first operational amplifier 16a1.
The level of the DC output from 7 will also change.

The DC output of the smoothing circuit 17 is the control circuit 1
8, the control circuit 18 judges the seating status of the occupant based on a comparison between the threshold value data stored in advance and the stored signal data. Smoothing circuit 1 regardless of the situation
If only the DC output of No. 7 changes, it is judged that it does not match the actual seating situation. For example, when a child occupant SP is seated in the seat 1, it may be determined that an adult is seated due to a change in the level of the DC output, making it difficult to appropriately control the airbag device 30. Therefore, there is a problem that not only the accuracy of the judgment in the control circuit 18 is impaired, but also its reliability is lowered.

Further, the amplitude of the high frequency low voltage supplied from the electric field generating means 11 to the antenna electrode portions 4a to 4d is influenced and changed by, for example, power supply fluctuation. For example, if the amplitude of the high frequency low voltage increases, the level of the DC output voltage Vd of the AC-DC conversion circuit 15 also relatively increases, and conversely, if the amplitude of the high frequency low voltage decreases, AC- DC output voltage Vd of the DC conversion circuit 15
The level of is also relatively small. Since this level fluctuation occurs regardless of the seating status of the occupant seated in the seat 1, when the amplitude of the high frequency low voltage fluctuates, the AC
The level of the DC output voltage Vd of the −DC converting circuit 15 becomes higher or lower than the original normal level. Therefore, when the control circuit 18 compares the threshold value regarding the seating condition of the occupant stored in advance with the signal data fetched from the AC-DC conversion circuit 15, the control circuit 18 accurately determines the condition corresponding to the seating condition of the occupant. It becomes difficult to make a decision, and the inconvenience of operating the airbag device 30 by erroneously determining "seating by a child" as "seating by an adult" or "vacant seat" occurs, and the reliability of the device also increases. There is also the problem of being significantly impaired.

Therefore, an object of the present invention is to detect the existence of an object regardless of the fluctuation of the amplitude of the electric field generating means and the ambient temperature.
An object of the present invention is to provide an object detection device and an occupant detection system capable of accurately detecting the seating condition of an occupant in a seat with high accuracy.

[0030]

SUMMARY OF THE INVENTION Therefore, the present invention has been proposed to achieve the above-mentioned object, and comprises the first aspect of the present invention.
The present invention relates to an object detection device, and the eleventh to twenty-first inventions relate to an occupant detection system.

That is, in the first to tenth aspects of the invention relating to the object detection device, the first aspect of the invention is to output a substantially sinusoidal alternating current to the antenna electrode and to generate a weak electric field around the antenna electrode. Electric field generating means for generating, an n-terminal circuit network having two or more terminals connected between the antenna electrode and the electric field generating means, and a signal (original signal) on the side of the electric field generating means in the n-terminal circuit network. ) And a signal (load signal) on the antenna electrode side for detecting a phase difference between the signals, and a phase component based on the load impedance of the n-terminal circuit network is detected to detect the vicinity of the antenna electrode. It is characterized by detecting whether or not an object exists in the.

A second invention of the present invention is to provide an antenna electrode, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrode, the antenna electrode and the electric field. An n-terminal circuit network having two or more terminals connected between the generating means and a position of a signal (original signal) on the electric field generating means side and a signal (load signal) on the antenna electrode side in the n-terminal circuit network. A phase detection circuit that detects a phase difference and a control circuit that receives a signal output from the phase detection circuit and determines whether or not an object exists near the antenna electrode based on the data of the signal are provided. By detecting a phase component based on the load impedance of the n-terminal circuit network, it is detected whether or not an object exists near the antenna electrode.

A third aspect of the present invention is to provide an antenna electrode, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrode, the antenna electrode and the electric field. An n-terminal circuit network having two or more terminals connected between the generating means and a position of a signal (original signal) on the electric field generating means side and a signal (load signal) on the antenna electrode side in the n-terminal circuit network. A phase detection circuit that detects a phase difference and a control circuit that receives a signal output from the phase detection circuit and determines whether or not an object exists near the antenna electrode based on the data of the signal are provided. The phase detection circuit is connected to at least first and second conversion circuits that convert the analog signals of the original signal and the load signal into digital signals with respect to a reference voltage, and are connected to the first and second conversion circuits. And a signal corresponding to a phase component based on the load impedance of the n-terminal circuit network from the exclusive OR circuit based on the signals from the first and second conversion circuits. It is characterized by outputting.

A fourth invention of the present invention is to provide an antenna electrode, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrode, the antenna electrode and the electric field. An n-terminal circuit network having two or more terminals connected between the generating means and a position of a signal (original signal) on the electric field generating means side and a signal (load signal) on the antenna electrode side in the n-terminal circuit network. A phase detection circuit that detects a phase difference, an integration circuit that integrates the output signal of the phase detection circuit and converts it to a DC signal, and a signal that is output from the integration circuit, and the antenna electrode based on the data of this signal. And a control circuit for determining whether or not an object exists in the vicinity of, the phase detection circuit, at least,
It is composed of first and second conversion circuits for converting analog signals of the original signal and the load signal into digital signals with respect to the reference voltage, and an exclusive OR circuit connected to the first and second conversion circuits. A signal corresponding to a phase component based on the load impedance of the n-terminal network is output from the exclusive OR circuit to the integrator circuit based on the signals from the first and second conversion circuits. To do.

Further, a fifth aspect of the present invention is to provide a plurality of antenna electrodes, an electric field generating means for outputting a substantially sinusoidal alternating current, and generating a weak electric field around the antenna electrodes.
An n-terminal having a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the plurality of antenna electrodes, and two or more terminals connected between the electric field generating means and the switching circuit. A circuit network and a phase difference between a signal (original signal) on the side of the electric field generating means and a signal (load signal) on the side of the specific antenna electrode sequentially selected by the switching circuit are detected in the n-terminal circuit network. A phase detection circuit, an integration circuit that integrates the output signal of the phase detection circuit and converts it to a DC signal, and a signal output from this integration circuit is taken in, and an object near the antenna electrode based on the data of this signal. And a control circuit for determining whether or not there is a signal, the phase detection circuit converts at least an analog signal of an original signal and a load signal into a digital signal with respect to a reference voltage. The exclusive OR circuit is composed of first and second conversion circuits and an exclusive OR circuit connected to the first and second conversion circuits, and the exclusive OR circuit is formed on the basis of signals from the first and second conversion circuits. The OR circuit outputs a signal corresponding to the phase component based on the load impedance of the n-terminal circuit network to the integrating circuit.

Further, a sixth invention of the present invention is characterized in that the n-terminal circuit network is mainly composed of a transformer having a resistor or a primary coil and a secondary coil, and the seventh invention is characterized in that The detection circuit is configured such that a plurality of phase detection circuits are connected in parallel and the signals from the respective phase detection circuits are added and output, and the eighth invention is the first invention. , The second conversion circuit is composed of a comparator, the ninth invention is,
A buffer circuit is connected in series to an input system of the original signal and the load signal to the first and second conversion circuits, and a tenth aspect of the invention is that the control circuit includes at least the antenna electrode of Means for storing threshold data relating to the existence of an object existing in the vicinity, means for capturing a signal regarding the phase difference, and comparing the data of the captured signal with the threshold data, The present invention is characterized in that it has a judging section for judging the existence status.

On the other hand, in the eleventh invention to the twenty-first invention relating to the occupant detection system, the eleventh invention of the present invention outputs substantially sinusoidal alternating current to the seat and / or the antenna electrode arranged in the periphery thereof, An electric field generating means for generating a weak electric field around the antenna electrode, an n-terminal circuit network having two or more terminals connected between the antenna electrode and the electric field generating means, and the n-terminal circuit network A phase detection circuit for detecting the phase difference between the signal (original signal) on the side of the electric field generating device and the signal (load signal) on the side of the antenna electrode, and the signal output from this phase detection circuit is taken in and the data of this signal is acquired. A control circuit for determining the seating condition of the occupant based on the seat, and detecting the phase component based on the load impedance of the n-terminal circuit network, And detecting and whether the passenger is seated.

The twelfth aspect of the present invention is to generate an electric field for generating a weak electric field around the antenna electrode by outputting a substantially sinusoidal alternating current with the antenna electrode arranged on the sheet and / or its periphery. And n having two or more terminals connected between the antenna electrode and the electric field generating means.
A terminal circuit network, a phase detection circuit for detecting a phase difference between a signal (original signal) on the side of the electric field generating means and a signal (load signal) on the side of the antenna electrode in the n-terminal circuit network, and from this phase detection circuit And a control circuit for determining an occupant's seating condition on the seat based on the data of the output signal, wherein the phase detection circuit has at least the original signal and the load signal with respect to the reference voltage. It is composed of first and second conversion circuits for converting an analog signal into a digital signal and an exclusive OR circuit connected to the first and second conversion circuits. The exclusive OR circuit outputs a signal corresponding to a phase component based on the load impedance of the n-terminal circuit network based on the signal of (1).

A thirteenth aspect of the present invention is to generate an electric field for generating a weak electric field around the antenna electrode by outputting a substantially sinusoidal alternating current with the antenna electrode arranged on the sheet and / or its periphery. And n having two or more terminals connected between the antenna electrode and the electric field generating means.
A terminal circuit network, a phase detection circuit for detecting a phase difference between a signal (original signal) on the side of the electric field generating means and a signal (load signal) on the side of the antenna electrode in the n-terminal circuit network, and a phase detection circuit for the phase detection circuit. An integrating circuit that integrates the output signal and converts it into a DC signal, and a control circuit that takes in the signal output from this integrating circuit and determines the seating status of the occupant on the seat based on the data of this signal, The phase detection circuit converts at least first and second analog signals of the original signal and the load signal into digital signals with respect to a reference voltage.
And the exclusive OR circuit connected to the first and second conversion circuits, and based on the signals from the first and second conversion circuits, the exclusive OR circuit, A signal corresponding to the phase component based on the load impedance of the n-terminal network is output.

Further, a fourteenth aspect of the present invention is for outputting a substantially sinusoidal alternating current with a plurality of antenna electrodes arranged on the sheet and / or its periphery to generate a weak electric field around the antenna electrodes. Electric field generating means, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among a plurality of the antenna electrodes, and two terminals connected between the electric field generating means and the switching circuit. An n-terminal circuit network having the above, a signal (original signal) on the side of the electric field generating means in the n-terminal circuit network, and a signal (load signal) on the side of the specific antenna electrode sequentially selected by the switching circuit. A phase detection circuit that detects the phase difference, an integration circuit that integrates the output signal of this phase detection circuit and converts it to a DC signal, and a signal that is output from this integration circuit,
A control circuit for determining the seating condition of the occupant based on the data of this signal, and whether the occupant is seated in the seat by detecting the phase component based on the load impedance of the n-terminal circuit network. It is characterized by detecting whether or not.

Further, a fifteenth aspect of the present invention is for outputting a substantially sinusoidal alternating current with a plurality of antenna electrodes arranged on the sheet and / or its periphery to generate a weak electric field around the antenna electrodes. An electric field generating means, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the plurality of antenna electrodes, and a switching circuit connected between the switching circuit and the plurality of antenna electrodes. A plurality of n-terminal circuits having terminals or more, a signal (original signal) on the switching circuit side (electric field generating means side) in each of the n-terminal circuits, and the specific antenna sequentially selected by the switching circuit A plurality of phase detection circuits that detect a phase difference with the signal on the electrode side (load signal), a plurality of integration circuits that integrate the output signals of the respective phase detection circuits and convert into a DC signal; A control circuit for taking in signals output from each of the integrating circuits and judging the seating condition of the occupant on the seat based on the data of these signals, and each of which is switched / selected by the switching circuit. By detecting the phase component based on the load impedance of the n-terminal circuit network, it is detected whether or not the occupant is seated in the seat.

The sixteenth aspect of the present invention is to generate an electric field for generating a weak electric field around the antenna electrode by outputting a substantially sinusoidal alternating current with the antenna electrode arranged on the sheet and / or its periphery. And n having two or more terminals connected between the antenna electrode and the electric field generating means.
A terminal circuit network, a phase detection circuit for detecting a phase difference between a signal (original signal) on the side of the electric field generating means and a signal (load signal) on the side of the antenna electrode in the n-terminal circuit network, and from this phase detection circuit A control circuit that takes in the output signal and judges the seating condition of the occupant based on the data of this signal and the function that can set the airbag to a predetermined operation mode based on the judgment result of this control circuit An airbag device having the airbag device, comprising: determining a seating condition of an occupant on a seat by detecting a phase component based on a load impedance of the n-terminal circuit network; and an airbag of the airbag device based on the determination result. Is set to a deployable state or an undeployable state. Furthermore, a seventeenth aspect of the present invention is that the n-terminal circuit network is
An eighteenth aspect of the present invention is characterized in that the phase detection circuit is configured by connecting a plurality of phase detection circuits in parallel and detecting each phase. It is characterized in that the signals from the circuits are added and output.
A ninth aspect of the invention is characterized in that the first and second conversion circuits are composed of comparators, and a twentieth aspect of the invention is to input an original signal and a load signal to the first and second conversion circuits. A buffer circuit is connected in series to
According to a first aspect of the invention, the control circuit stores at least means for storing threshold value data regarding a seating condition of an occupant in a seat, means for capturing a signal regarding a phase difference, data of the captured signal and the threshold. It is characterized in that it has a judging section for judging the seating status of the occupant in the seat by comparing with the value data.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a first embodiment in which the object detection device according to the present invention is applied to an occupant detection system will be described with reference to FIGS. FIG. 1 is a block diagram of the basic system, and FIG. 3 shows an electric circuit diagram of a system embodying the basic system of FIG. Incidentally, FIG.
The same parts as those of the prior art shown in FIG. 16 are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, a control unit 10A is incorporated in the seat 1 shown in FIG. 12, for example. The control unit 10A outputs, for example, a substantially sinusoidal alternating current (for example, high frequency low voltage) to generate a weak electric field around one antenna electrode 4 arranged in the seating portion 1a of the seat 1 shown in FIG. Electric field generating means 41,
An n-terminal circuit network 42 having two or more terminals connected between the electric field generating means 41 and the antenna electrode 4, and an n-terminal circuit network 42 arranged in the housing of the control unit 10A.
14 connected to the output side (antenna electrode side) of the
a and a phase component based on the load impedance of the n-terminal network 42 by supplying an AC signal from the electric field generating means 41 to the antenna electrode 4 (phase difference Pd ... See FIG. 2).
Is a signal (original signal) VA on the side of the electric field generating means and a signal (load signal) V on the side of the antenna electrode in the n-terminal circuit network 42.
A phase detection circuit 43 that detects the phase difference signal based on B, an integration circuit 44 that integrates the phase difference signal output from the phase detection circuit 43 and converts it into a DC signal, a CPU, an A / D converter, an external memory (for example, It is composed of a control circuit 18 including EEPROM, RAM, etc., a connector 19 arranged in the housing and connected to a battery power supply (not shown), and a power supply circuit 20 connected to the connector 19. These components are housed in the same housing to form the control unit 10A, and for example, the seating portion 1a of the seat 1 is provided.
Is fixed to the seat frame 3 so as not to be exposed to the seating side of the occupant. To the control circuit 18 of the control unit 10A, for example, an airbag device 30 having the configuration shown in FIG. 16 is connected.

Such a basic system is specifically constructed as shown in FIG. 3, for example. The control unit 10A includes, for example, an electric field generating means 41, a resistor 42a and an amplifier circuit 42b, an n-terminal circuit network 42 connected between the electric field generating means 41 and the connector 14a (antenna electrode 4), and a reference. First and second conversion circuits 43a and 43b and first and second conversion circuits 43a and 43a, which convert the analog signals of the original signal and the load signal into digital signals with respect to the voltage.
Phase detection circuit 43 including a resistor 43c connected to the inverting input terminal (-) of 43b and an exclusive OR circuit 43d.
And a resistor 44a and a capacitor 44b, and an integration circuit 4 for converting the signal from the phase detection circuit 43 into a DC signal.
4, a buffer connected between the electric field generating means side of the n-terminal circuit network 42, the antenna electrode side and the non-inverting input terminals (+) of the first and second conversion circuits 43a and 43b of the phase detection circuit 43. The circuits 45 and 46 and the control circuit 18
And a power supply circuit 20. Incidentally, the first and second conversion circuits 43a and 43b in the phase detection circuit 43.
The reference voltage Vref is applied to the inverting input terminal (-) of the above through the resistor 43c.

In the above-mentioned control unit 10A, the electric field generating means 41 is constituted by a quadrature oscillation circuit that outputs a substantially sinusoidal alternating current (for example, high frequency low voltage) as shown in FIG. .5
A high frequency low voltage of 3VP-P with a midpoint of V (DC bias voltage) is used. As the oscillation circuit, a Wien bridge oscillation circuit or the like can be used in addition to the quadrature oscillation circuit. In particular, the electric field generating means 41 can also be configured to divide the clock signal of the control circuit 18 into a sine wave alternating current, which is excellent in terms of simplification of the circuit configuration and economical efficiency, and is recommended. It

In the control unit 10A described above,
The n-terminal circuit network 42 is constituted by connecting an amplifier circuit 42b in series to a resistor 42a, but depending on the signal level from the electric field generating means 41, for example, the amplifier circuit 4 may be used.
It is also possible to omit 2b and configure with only the resistor 42a. The signal (original signal) VA on the side of the electric field generating means and the signal (load signal) VB on the side of the antenna electrode in this n-terminal circuit network 42 are input to the phase detection circuit 43 via the buffer circuits 45 and 46. This buffer circuit 45,
The numeral 46 is composed of, for example, an operational amplifier having an amplification factor of approximately 1.

In the control unit 10A described above,
The phase detection circuit 43 includes the first and second conversion circuits 43a and 43
Although it is configured by b and the exclusive OR circuit 43d, the first and second conversion circuits 43a, 43b are preferably comparators configured by, for example, operational amplifiers. A reference power source is connected to each of the inverting input terminals (−) of the first and second conversion circuits 43a and 43b via a resistor 43c, and a reference voltage Vref of 5 V, for example, is applied.

Further, in the above-mentioned control unit 10A, the control circuit 18 is composed of a CPU, an A / D converter, an external memory, etc., and at least the existence state of an object existing in the vicinity of the antenna electrode 4 (for example, a sheet). 1) occupant's seating condition), etc., means for storing threshold value data, means for capturing a signal related to phase difference, and comparison of the captured signal data and threshold value data to determine the presence state of an object ( For example, the occupant's seating condition) and the like.

The occupant detection system configured as described above operates as follows. First, when the electric field generating means 41 is in an operating state, a high frequency low voltage VA of substantially sinusoidal alternating current is output from it as shown in FIG. This output voltage VA is supplied to an n-terminal circuit network 42 composed of a resistor 42a and an amplifier circuit 42b, and an output side (antenna electrode side) of the n-terminal circuit network 42 has a phase difference Pd as shown in FIG. 4B. The voltage VB it has appears. This high frequency output voltage VB is supplied to the antenna electrode 4 via the connector 14a. As a result, a weak electric field is generated around the antenna electrode 4, and a load corresponding to the seating status such as whether or not the occupant is seated in the seat 1 and the occupant's identification (discrimination between an adult and a child) is generated in the antenna electrode 4. A current having a different phase difference flows according to the impedance. Since the currents having different phase differences flow in this manner, both ends of the n-terminal network 42 are connected to each other as shown in FIG.
As shown in (a) and (b), voltages VA and VB having a phase difference Pd according to the load impedance are generated.

For example, in the vacant state in which the occupant is not seated on the seat 1, although a low level current flows based on a small stray capacitance existing around the antenna electrode 4 as a load of the n-terminal circuit network 42, The voltage VB on the load side of the n-terminal circuit network 42 has a small phase difference Pd with respect to the voltage VA on the electric field generating means 41 side. On the other hand, when an occupant is seated on the seat 1, a large capacitance component is present around the antenna electrode 4 as compared with the stray capacitance in the empty state, and a high level current flows. Become. Since the capacitance component of the occupant is larger in the adult than in the child, the level of the current flowing through the antenna electrode 4 is also high and the phase difference Pd is large.

As described above, the voltages VA and VB across the n-terminal circuit network 42 having the phase component corresponding to the seating condition are passed through the buffer circuits 45 and 46 to the first and second conversion circuits 43a in the phase detection circuit 43. , 43b of the non-inverting input terminal (+). The first and second conversion circuits 43
Since, for example, the reference voltage Vref of 5V is applied to the inverting input terminals (-) of a and 43b through the resistor 43c as described above, the respective voltages VA and VB reach the 0 point (middle point). At this time, output signals VCA and VCB having a phase difference Pd are output as shown in FIGS. 4 (c) and 4 (d). The signals VCA and VCB are the exclusive OR circuit 43d.
4E, and only one of the output signals VCA and VCB of the first and second conversion circuits 43a and 43b is high, as shown in FIG. 4E. The level signal is output. This output signal is input to the integration circuit 44, and the resistor 44a and the capacitor 44b are connected.
Is integrated based on the above, and converted into a DC signal VD as shown in FIG. The integrating circuit 44 has a function as a low-pass filter and removes undesired noise components.

In particular, the output signal VD from the integration circuit 44 differs depending on the phase component based on the seating condition of the occupant as shown in FIG. 4 (f), and the DC signal VD shown by the solid line.
Indicates the DC conversion level when the occupant is seated, and the DC output VEM indicated by the dotted line indicates the DC conversion level when the occupant is seated, and there is a discernible level difference between them. The DC signal VD is successively taken into the control circuit 18, A / D converted, and stored in the memory means.

The control circuit 18 previously stores, for example, a threshold value (threshold value data) relating to the seating status of the occupant seated on the seat 1 (whether seated or not, identification of adult or child, etc.). Stored in the means. Specifically, the threshold value regarding whether or not a passenger is seated is set as follows. For example, when an adult or a child occupant is seated on the seat 1, the antenna electrode 4 is
The capacitance component existing around is large. As a result, the level of the current flowing through the antenna electrode becomes large, and a discriminable phase difference Pd is generated between them, and the output signal VD of the integrating circuit 44 becomes the level shown by the solid line in FIG. 4 (f). Become. Therefore, in FIG. 4 (f), the threshold VSH indicated by the alternate long and short dash line regarding whether or not the occupant is seated is set between the vacant DC output VEM indicated by the dotted line and the sitting DC signal VD indicated by the solid line. .
In the case of identifying the occupant, the DC signal VD shown by the solid line in FIG. 4 (f) is subdivided into signals corresponding to the occupants of adults and children, and the threshold value for occupant identification is based on these. Is set.

Therefore, the signal data (VD) relating to the seating status of the occupant, which is taken into the control circuit 18, is compared with the threshold value data (VSH) relating to the seating status of the occupant stored in the control circuit 18 in advance. For example, when the DC output VD from the integrating circuit 44 is larger than the threshold value (VSH) regarding the presence or absence of seating, it is determined that the occupant is seated in the seat 1. As a result, the airbag device 30 shown in FIG. 16 is set so that the airbag can be deployed by the transmission signal from the control circuit 18. In particular, when a threshold value for identifying the occupant is set, different judgment is made depending on whether or not the occupant is an adult. That is, when it is determined that the occupant is an adult, the airbag is set to be inflatable, while conversely, when the occupant is determined to be a child, the airbag is set to be inflatable. If the DC output is smaller than the threshold value (VSH), it is determined that the seat is vacant, and the airbag is set so that it cannot be deployed. That is, the transmission signal from the control circuit 18 is input to the control circuit CC of the airbag device 30, and in the latter case, it is set so as not to supply the gate signal to the switching element SW2 on the passenger side when the vehicle collides. A gate signal is supplied to the switching element SW1 on the driver's seat side. In the former case, the gate signals are set to be supplied to the switching elements SW1 and SW2.

According to this embodiment, the n-terminal circuit network 42 is connected with the phase detecting circuit 43 for detecting the phase difference Pd using the voltages VA and VB across the n-terminal circuit network 42. If the frequency of the AC output from the electric field generating means 41 is constant, Pd is kept substantially constant even if the amplitude of the AC output fluctuates or the ambient temperature changes. Therefore, even if the amplitude of the AC output from the electric field generating means 41 changes due to power supply fluctuation, the phase component based on the load impedance is kept substantially constant, and as a result, the occupant's seating condition (object presence condition) is accurately determined. In addition, since the number of the antenna electrode 4 is one, the cost of the system or the device can be reduced by simplifying the circuit configuration.

The phase detection circuit 43 is mainly composed of first and second conversion circuits 43a and 43b which are comparators and an exclusive OR circuit 43d, and the first and second conversion circuits 43a and 43b. Since the reference voltage Vref is applied to the inverting input terminal (-) of the same via the resistor 43c, the reference voltages Vref of the voltages VA and VB input to the first and second conversion circuits 43a and 43b by the reference voltage Vref. The zero-cross point can be accurately detected, and the exclusive OR circuit 43d
Thus, the signal corresponding to the phase difference between the two signals can be extracted. Therefore, by taking this taken out signal into the control circuit 18, it is possible to accurately judge the occupant's seating condition (object existence condition), and the airbag device 3
0 can be operated properly.

In particular, the output signal of the phase detection circuit 43 is converted into a DC signal by the integration circuit 44, and the integration circuit 4
Since the undesired noise component is removed by the low-pass filter function of No. 4, it is easy to take in the control circuit 18, and the comparison / judgment processing with the threshold value can be easily performed.

Further, the control unit 10A is constructed compactly by accommodating the circuit elements such as the electric field generating means 41, the n-terminal circuit network 42, the phase detecting circuit 43, the integrating circuit 44, the control circuit 18 and the power supply circuit 20 in the same housing. As a result, the assembly into the seat 1 is facilitated. In particular, since it is relatively easy to secure an arrangement space in or near the seat frame 3 in the seating portion 1a, the control unit 10
Even if A is slightly larger, it can be easily and easily incorporated.

Further, the sheet 1 on which the antenna electrode 4 is arranged
Since the control unit 10A is incorporated in the control unit 10A, the wiring length of the control unit 10A for connecting the antenna electrode 4 and the control unit 10A to each other by a lead wire is set to the dashboard portion or the engine room. It can be made considerably shorter than the case where it is arranged. Therefore, not only the cost can be reduced, but also the influence of external noise can be reduced by shortening the wiring length.
The reliability of the occupant detection function of the system can be improved.

Furthermore, the airbag of the airbag device 30 can be set to either a deployable state or an undeployable 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 a child based on the level of the DC output of the integration circuit 44, the airbag of the airbag device 30 is set to the undeployable state. Therefore, even if a vehicle collides, the airbag will not be deployed and the airbag device 30 can be controlled appropriately.

FIG. 5 shows a second embodiment of the occupant detection system (object detection device) according to the present invention.
FIG. 5A is a basic circuit block diagram, and FIG. 5B is a specific electric circuit diagram thereof. The basic structure of the control unit is the same as that of the embodiment shown in FIGS. The only difference is that the phase detection circuit 43A has a plurality of phase detection circuits 431, 432 ... 43n connected in parallel.
43n, and the integration circuit 44A is connected in series to the plurality of phase detection circuits 431, 432 ... 43n.
And a plurality of integrating circuits 441, 442.
.. The output of 44n is added by the adder circuit 47.

According to this embodiment, the voltages VA and VB on the input and output sides of the n-terminal network 42 are the phase detection circuit 43A.
43n are input to the plurality of phase detection circuits 431, 432, ... 43n, the phase difference is detected, and the addition is performed by the addition circuit 47 via the integration circuit 44A.
It is possible to increase the level of the DC signal VD that is taken in by 8. Therefore, it becomes possible to more accurately detect the occupant's seating status (object presence status).

FIG. 5B is a specific electric circuit diagram of FIG. 5A, and the phase detection circuit 43A is composed of a plurality of exclusive OR circuits 43d1, 43d2 ... 43d4. The adding circuit 47 is composed of a plurality of resistors 47a and a transformer 47b having a plurality of primary coils 47p and one secondary coil 47s, and the integrating circuit 44A is composed of a resistor 44a and a capacitor 44b.

According to this embodiment, the phase difference between the voltage VB on the output side and the voltage VA on the input side of the n-terminal network 42 detected by the exclusive OR circuits 43d1, 43d2 ... 43d4 is calculated. The corresponding signal is the resistance 4
Each primary coil 4 of the transformer 47b via 7a
It is input to 7p, added, and output to the secondary coil 47s. This output signal is integrated by the integrating circuit 44A and taken into the control circuit 18. Then, the same effect as that of the basic circuit shown in FIG. 5A is expected.

FIG. 6 shows a third embodiment of the occupant detection system according to the present invention, and the basic circuit configuration is the same as that of the first embodiment shown in FIG. The difference is n
The terminal circuit network 42A is composed of the resistor 42a, the amplifier circuit 42b, and the transformer 42c. The transformer 42c is configured by winding, for example, a primary coil and a secondary coil around a ring core. The primary coil (input side) has the electric field generating means 41, and the secondary coil (output side) has the resistor 4c.
The antenna electrodes 4 are respectively connected via 2a and the amplifier circuit 42b. The voltage V of the n-terminal circuit network 42A
A and VB are the primary coil side of the transformer 42c and the amplifier circuit 4
Although it is taken out from the output side of 2b, the voltage VA can also be taken out from the secondary coil side (connection point between the secondary coil and the resistor 42a).

According to this embodiment, basically the same effect as that of the first embodiment can be obtained. Moreover, the electric field generating means 4
Even if the AC signal from 1 is small, the voltage can be boosted to an appropriate voltage by the transformer 42c, so that the cost can be reduced by simplifying the circuit configuration of the electric field generating means 41.

FIG. 7 shows a fourth embodiment of the occupant detection system according to the present invention, and the basic circuit configuration is the same as that of the first embodiment shown in FIG. The different points are that the antenna electrode is composed of a plurality of antenna electrodes 4 (4a to 4d) as shown in FIGS. The switching circuit 48 having a plurality of switching means 48a to 48d is connected between the antenna electrode 4 (4a to 4d). Incidentally, the switching means 48a of the switching circuit 48
.About.48d are appropriately switched and operated based on a signal from the control circuit 18.

According to this embodiment, basically the same effect as that of the first embodiment can be obtained. Moreover, since the plurality of antenna electrodes 4 (4a to 4d) are arranged on the sheet 1, many signals corresponding to the phase component based on the load impedance of each antenna electrode are selectively selected by the switching circuit 48. It can be taken into the control circuit 18 via the phase detection circuit 43 and the integration circuit 44. Therefore, the control circuit 18 can determine the seating condition of the occupant based on a large amount of information, the determination accuracy can be further improved, and the airbag device 30 can be operated more appropriately. Will be possible.

FIG. 8 shows a fifth embodiment of the occupant detection system according to the present invention, and the basic circuit configuration is the same as that of the first embodiment shown in FIG. The difference is that the plurality of antenna electrodes 4 (4a to 4d) are connected to the connectors 14a to 14d.
N terminal network 42, phase detection circuit 43,
That is, a plurality of detection units Da to Dd including the integration circuit 44 are connected, and a switching circuit 48 is connected between the electric field generating means 41 and the plurality of detection units Da to Dd. According to this embodiment, the same effect as the embodiment shown in FIGS. 1 and 7 can be obtained.

In particular, if the antenna electrode 4 is arranged on the dashboard or on the side support portion of the door or seat, it is detected that, for example, a passenger in the passenger seat is lying down and the distance between them is narrowed more than necessary, and the airbag device is detected. Or you can stop the deployment operation of the side airbag device,
It is possible to detect not only the presence / absence of an occupant but also the identification of the occupant's seating posture.

The first occupant detection system according to the present invention is as follows.
The fifth embodiment is not limited to the above-described embodiments, and is applied to, for example, detecting the seating status of an occupant on a seat, and also detects the existence status of any dielectric object. It can be applied to devices. Therefore,
Depending on the application, the device may be an antenna electrode, an electric field generating means,
It can also be composed of an n-terminal circuit network and a phase detection circuit. In particular, it is recommended that the phase detection circuit be practically composed of a plurality of comparators and an exclusive OR circuit. Further, the electric field generating means is not limited to the quadrature oscillation circuit and the Wien bridge oscillation circuit as long as it can generate a sinusoidal alternating current, and the output frequency thereof is 125K.
It can be set to anything other than Hz, and its voltage is 3VP.
It is also possible to set a voltage other than -P. Further, when applied to the occupant detection system, the antenna electrode can be arranged not only on the seating portion of the seat but also on the backrest portion, the side support portion, or on the dashboard or door near the seat. The number of arranged antenna electrodes can be appropriately increased or decreased, and the shape thereof can be formed in a rectangular shape, a band shape, a ring shape, a spiral shape, etc. in addition to the rectangular shape, and the antenna electrode portion arranged on the base member is covered with an insulating cover. It can also be covered by a member. Further, based on the determination result of the control circuit, it is possible to control the seat belt wearing state, a warning light, etc. instead of the airbag device. Further, the occupant determination is performed by comparing the threshold value stored in advance in the control circuit with the phase difference data related to the actual load impedance of the antenna electrode, as well as various seating patterns and seating postures of the occupant. It is also possible to store data relating to the occupant in advance and compare it with this to determine whether or not the occupant is seated, whether or not the occupant is an adult.

[0073]

As described above, according to the present invention, the n-terminal circuit network is connected to the phase detecting circuit for detecting the phase component by utilizing the voltage across the n-terminal circuit network. Even if the amplitude of fluctuates, the phase component is not affected. Therefore, even if the amplitude of the AC output from the electric field generating means fluctuates due to fluctuations in the power supply, the phase component based on the load impedance is kept almost constant, and as a result, the existence state of the object can be accurately determined, and the system or The cost of the device can be reduced.

Further, if the phase detection circuit is composed of the first and second conversion circuits composed of comparators and the exclusive OR circuit, the voltage input to the first and second conversion circuits by the reference voltage The zero-cross point can be detected accurately, and the signal corresponding to the phase difference between the two signals can be taken out by the exclusive OR circuit. Therefore, by taking this signal into the control circuit, it is possible to accurately determine the existence state of the object. In particular, when applied to an occupant detection system equipped with an airbag device, the airbag device can be operated appropriately.

Particularly, if the output signal of the phase detection circuit is configured to be integrated by the integrator circuit, undesired noise components can be removed by the low-pass filter function of the integrator circuit. Highly reliable judgment processing is possible.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a first embodiment of an occupant detection system according to the present invention.

FIG. 2 is a voltage waveform diagram at both ends of an n-terminal network.

FIG. 3 is an electric circuit diagram showing a specific example of FIG.

4A and 4B are diagrams for explaining the operation of the control unit shown in FIG. 3, in which FIG. 4A is a voltage waveform diagram on the side of an electric field generating means of an n-terminal circuit network, and FIG. 4B is an n-terminal. Voltage waveform diagram on the antenna electrode side of the circuit network, FIG. 7C is an output waveform diagram of the first conversion circuit, FIG. 7D is an output waveform diagram of the second conversion circuit, and FIG. The output waveform diagram of the logical OR circuit, and FIG. 6F is a diagram showing the output voltage of the component circuit.

5A and 5B show a second embodiment of the occupant detection system (object detection device) according to the present invention, in which FIG. 5A is a basic circuit block diagram and FIG. It is an electric circuit diagram of a specific example of (a).

FIG. 6 is an electric circuit diagram showing a third embodiment of the occupant detection system according to the present invention.

FIG. 7 is an electric circuit diagram showing a fourth embodiment of an occupant detection system according to the present invention.

FIG. 8 is an electric circuit diagram showing a fifth embodiment of an occupant detection system according to the present invention.

FIG. 9 is an electric circuit diagram of an airbag device according to a conventional example.

FIG. 10 is an electric circuit diagram of an improved airbag device according to a conventional example.

11A and 11B are views for explaining the basic operation of the occupant detection system according to the prior art, where FIG. 11A is a diagram showing an electric field distribution around the antenna electrode, and FIG. 11B is a diagram showing the antenna electrode. It is a figure which shows the electric field distribution when an object exists in the vicinity.

12A and 12B are views showing a seat portion of an occupant detection system according to a prior art, wherein FIG. 12A is a side view showing an arrangement state of antenna electrodes on the seat, and FIG. ) Is a plan view of FIG.

13A and 13B are specific configuration diagrams of the antenna electrode shown in FIG. 12, in which FIG. 13A is a plan view and FIG.
Is a sectional view taken along the line XX of FIG. 3, and FIG. 6C is a sectional view taken along the line YY of FIG.

FIG. 14 is an electric circuit diagram of an occupant detection system according to the prior art.

15 is a specific electrical circuit diagram of the AC-DC conversion circuit shown in FIG.

16 is an electric circuit diagram of the airbag device shown in FIG.

17A and 17B are diagrams for explaining the operation of the control unit shown in FIG. 14, in which FIG. 17A is a waveform diagram of the line voltage of the transmission system, and FIG. 17B is the output voltage of the full-wave rectifier circuit. FIG. 3C is a diagram showing the output voltage of the smoothing circuit.

FIG. 18 is a diagram for explaining a seated state of an occupant on a seat, FIG. 18A is a diagram showing an adult's seated state, and FIG. 18B is a diagram showing a child's seated state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 seat 1a seating part 1b backrest part 2 base 3 seat frame 4 (4a-4d) antenna electrode (antenna electrode part) 5 base member 6 (6a-6d) lead wire 10, 10A control unit 11 electric field generating means 12 resistance 13 switching Circuits 13a to 13d Switching means 14a to 14d Connector 15 AC-DC conversion circuit 16 Full wave rectifier circuit 16a1 First operational amplifier 16b2 Second operational amplifier 16b1 First diode 16b2 Second diode 16c1 to 16c3 Resistor 17 Smoothing circuit 17a Resistor 17b Capacitor 18 Control Circuit 19 Connector 20 Power Supply Circuit 30 Airbag Device 41 Electric Field Generating Means (Oscillation Circuit) 42, 42A n Terminal Circuit Network 42a Resistor 42b Amplification Circuit 42c Transformer 43, 43A Phase Detection Circuit 43a First Conversion Circuit 43b 43c EXCLUSIVE-OR circuit 43d1, 43d2 ... 43d4 EXCLUSIVE-OR circuit 431, 432, ... 43n Phase detection circuit 44, 44A Integrator circuit 441, 442, 44n Integrator circuit 44a Resistor 44b Capacitor 45, 46 Buffer circuit 47 Adder circuit 47a Resistor 47b Transformer 47p Primary coil 47s Secondary coil 48 Switching circuit 48a-48d Switching means SD Sensor Da-Dd Detection unit SS1, SS2 Safing sensor SQ1, SQ2 Squib SW1, SW2 Switching element CC Control circuit GS Electronic acceleration sensor E Antenna electrode OSC Oscillation circuit OB Object P Adult occupant SP Child occupant

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI G01S 13/04 G01S 13/04 (58) Fields investigated (Int.Cl. ⁷ , DB name) G01V 3/08 B60N 2/44 B60R 21/01 B60R 21/32 G01S 13/04

Claims (6)

(57) [Claims] 1. An antenna electrode, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrode, and 2 connected between the antenna electrode and the electric field generating means. An n-terminal circuit network having terminals or more, a signal (original signal) on the side of the electric field generating means and a signal (load signal) on the side of the antenna electrode in the n-terminal circuit network
Detecting a phase difference between then and a phase detection circuit, the position
Connect multiple phase detection circuits in parallel to each other
And the signals from the individual phase detection circuits.
Signal is added and output, and a phase component based on the load impedance of the n-terminal circuit network is detected to detect whether or not an object is present near the antenna electrode. Object detection device. 2. An antenna electrode, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrode, and 2 connected between the antenna electrode and the electric field generating means. An n-terminal circuit network having terminals or more, a signal (original signal) on the side of the electric field generating means and a signal (load signal) on the side of the antenna electrode in the n-terminal circuit network
And a phase detection circuit for detecting a phase difference between the phase detection circuit and a control circuit for taking in a signal output from the phase detection circuit and determining whether or not an object exists near the antenna electrode based on the data of the signal. And the phase detection circuit
Is connected by connecting multiple individual phase detection circuits in parallel.
The signals from the individual phase detection circuits are added to
An object which is configured to be output by being output and detects a phase component based on a load impedance of the n-terminal circuit network to detect whether or not an object exists near the antenna electrode. Detection device. 3. A sheet and / or an antenna electrode arranged in the periphery thereof, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field in the periphery of the antenna electrode, the antenna electrode and the electric field. An n-terminal circuit network having two or more terminals connected between the generating means and a position of a signal (original signal) on the electric field generating means side and a signal (load signal) on the antenna electrode side in the n-terminal circuit network. a phase detection circuit for detecting a phase difference takes a signal output from the phase detection circuit, and a control circuit for determining the seating state of the occupant of the seat based on the data of this signal, the
Connect the phase detection circuit to multiple individual phase detection circuits in parallel.
From each of the individual phase detection circuits
It is characterized in that signals are added and output, and by detecting a phase component based on the load impedance of the n-terminal circuit network, it is detected whether or not an occupant is seated in the seat. Occupant detection system. 4. A sheet and / or a plurality of antenna electrodes arranged on the periphery thereof, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrodes, and a plurality of the antennas. A switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode among the electrodes; and an n-terminal circuit network having two or more terminals connected between the electric field generating means and the switching circuit, A signal (original signal) on the side of the electric field generating means in the n-terminal circuit network
And a phase detection circuit that detects a phase difference between the signal (load signal) on the side of the specific antenna electrode that is sequentially selected by the switching circuit, and an output signal of the phase detection circuit is integrated and converted into a DC signal. The phase detection circuit includes an integrator circuit and a control circuit that takes in a signal output from the integrator circuit and determines the seating condition of the occupant based on the data of the signal. Circuit
Parallel connection and detection of each individual phase
Configured so that the signals from the circuit are added and output,
An occupant detection system, which detects whether or not an occupant is seated in a seat by detecting a phase component based on a load impedance of the n-terminal circuit network. 5. A sheet and / or a plurality of antenna electrodes arranged on the periphery thereof, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrodes, and a plurality of the antennas. Among the electrodes, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode, and a plurality of n-terminal circuits having two or more terminals connected between the switching circuit and the plurality of antenna electrodes. A network, a signal (original signal) on the switching circuit side (electric field generating means side) and a signal on the specific antenna electrode side (load signal) sequentially selected by the switching circuit in each of the n-terminal circuit networks. The plurality of phase detection circuits that detect the phase difference, the plurality of integration circuits that integrate the output signals of the respective phase detection circuits and convert into a DC signal, and the output from each of the integration circuits. Are captures the signal, and a control circuit for determining the seating state of the occupant of the seat based on the data of these signals, the phase detecting circuit, a plurality
The individual phase detection circuits of are connected in parallel and
The signals from the individual phase detection circuits are added and output
Configured to be, by detecting the phase component based on the load impedance of the switching circuit each of the n-terminal network which is switched-selected by detecting and whether the passenger in the seat is seated An occupant detection system characterized by the above. 6. A sheet and / or an antenna electrode arranged in the periphery thereof, an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field in the periphery of the antenna electrode, the antenna electrode and the electric field. An n-terminal circuit network having two or more terminals connected between the generating means and a position of a signal (original signal) on the electric field generating means side and a signal (load signal) on the antenna electrode side in the n-terminal circuit network. A phase detection circuit that detects the phase difference, a control circuit that takes in the signal output from this phase detection circuit and determines the seating status of the occupant based on the data of this signal, and the determination result of this control circuit the air bag includes an air bag device having a function capable of setting a predetermined operation mode Te, before
Use the phase detection circuit in parallel with multiple individual phase detection circuits.
From each individual phase detection circuit
Signal is added and output, and the occupant's seating condition in the seat is judged by detecting the phase component based on the load impedance of the n-terminal circuit network, and the air conditioner is judged based on the judgment result. An occupant detection system, wherein an airbag of a bag device is set to a deployable state or an undeployable state.