JP3393196B2 - 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 passenger side squib circuit consisting of a safing sensor SS2, a squib SQ2 and a switching element SW2 such as a field effect transistor, 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 of the safing sensors SS1 and SS2 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 deal with such a problem, for example, an airbag device as shown in FIG. 9 has been proposed. This airbag device is provided with a sensor SD for detecting whether or not an occupant is seated in the passenger seat, and the control circuit C is detected based on a detection signal from the sensor SD.
C determines the occupant's seating status in the passenger seat, and sets the airbag to either the deployable state or the undeployable state when the vehicle collides. In particular, a weight sensor is used as the sensor SD,
Based on the weight of the occupant measured by this weight sensor, it is possible to determine whether the child is an adult or a child. Is proposed.

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. 10 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 0 (a), the oscillator circuit OS is provided on 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. 11 to 15. 11 to 12 show the arrangement of the seat 1 and the antenna electrode 4 in the front passenger seat (or driver's seat). The seat 1 is mainly composed of a seat portion 1a and a backrest portion 1b. . The seating portion 1a includes, for example, a seat frame 3 fixed to a base 2 that is slidable forward and backward, a cushion material arranged on an upper portion of the seat frame 3, and an exterior material that covers the cushion material, and a backrest portion. The seat 1b is also made up of a seat frame, a cushion material, an exterior material, and the like, similar to the seating portion 1a. Particularly, the seating portion 1a has substantially the same shape (for example, a rectangular shape).
The plurality of antenna electrodes 4 (4a to 4d) formed on the back of the backrest portion 1 are symmetrically arranged apart from each other.
It may be arranged at b, or both.
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. 12, for example, the antenna electrode 4 is basically symmetrical with a base member 5 made of an insulating member such as a non-woven 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.

The control unit 10 incorporated in the above-mentioned sheet 1 outputs an electric field of sine wave as shown in FIG. 13, for example, and an electric field generating means for generating a weak 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. 15 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 (oscillation circuit) 11, its frequency is, for example, about 120 KHz, and the voltage is, for example, 5 VP to P, but 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. 14, for example. The full-wave rectifier circuit 16 includes a first operational amplifier 16a1, a second operational amplifier 16a2, and a first diode 16b1.
, The second diode 16b2, and the resistors 16c1-16
The smoothing circuit 17 includes a resistor 17a.
And a capacitor 17b. A control circuit 18 is connected to the output side of the AC-DC conversion circuit 15.

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 configured will be described with reference to FIGS. 13 to 17. 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 has a resistor 12, a transmission system, and a 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 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 4 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. 16A, and the line voltage V is different for adults and children because the capacitance component is different between the adult and the child and the current flowing through the antenna electrode 4 is different. It is small and large in children. On the other hand, when the occupant is not seated on the seat 1, the specific antenna electrode 4 (4a-4
Although a low-level current flows based on the stray capacitance existing around b), the voltage drop in the resistor 12 becomes extremely small and 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
16B, full-wave rectification is performed as shown in FIG. 16B, and subsequently, the smoothing circuit 17 converts it into direct current (Vd) as shown in FIG. 16C. 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 rectification circuit 16, an output voltage as shown in FIG. 16B 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. 16 (c), the dotted line shows the DC conversion level when the passenger is seated and the solid line shows the DC conversion level when the passenger is seated, and 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,
Depending on the size of the capacitance component existing around the antenna electrode 4, it becomes small when the capacitance is large like an adult, and conversely, when the capacitance is small like a child, the sheet 1 becomes large. It becomes the largest when the seat is empty. The DC output of the AC-DC conversion circuit 15 is successively taken into the control circuit 18,
It is 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. 17 (a) and 17 (b), when an adult occupant P and a child occupant SP are seated on the seat 1, respectively, due to differences in the areas facing the respective antenna electrodes 4, etc. A difference occurs in the capacitance component existing around each antenna electrode 4. As a result, the level of the current flowing through the antenna electrode 4 is different, the current level of the adult occupant P is higher than that of the child occupant SP, and the voltage drop across the resistor 12 is also different.
The DC level output from the C-DC conversion circuit 15 also has different levels. Therefore, a level between the direct current output related to the current level in the case of the child occupant SP and the direct current output in the vacant state shown by the dotted line in FIG. 16 (c) is set as the threshold value regarding whether or not the occupant is seated. It 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, it is desirable to set this threshold value with respect to the total sum of the DC output from the AC-DC conversion circuit 15 related to the current flowing in each antenna electrode 4,
It is also possible to set for each antenna electrode 4 (4a to 4d).

The threshold value for identifying the occupant is set as follows. For example, as shown in FIG. 17 (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 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. 16C. 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 4 (4a to 4d) becomes small, and the line voltage of the transmission system becomes small due to the voltage drop in the resistor 12. , AC-DC conversion circuit 1
The DC level output from No. 5 is between the levels shown by the solid line and the dotted line in FIG. 16 (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 judged as an adult occupant P, and if it is large, it is a child occupant SP.
Is determined. In particular, this threshold is AC-related to the current flowing through each antenna electrode 4 (4a-4d).
It is desirable to set the sum of the DC output from the DC conversion circuit 15, but it is also possible to set it for each antenna electrode 4 (4a to 4d).

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.
8 is compared with the threshold value data regarding the seating condition of the occupant stored in FIG. 8, and as shown in FIG. 17A, for example, 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. 15 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. 17B, 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. 15 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 switching elements SW1 and SW2 are set so that the gate signal is supplied.

As described above, according to the prior art, the antenna electrode 4 (4a ...
4d) flows a current according to a capacitance component existing around the antenna electrode 4 (4a to 4d), and at this time, a voltage drop corresponding to the current occurs in the resistor 12 connected to the transmission system, The line voltage of the transmission system is the antenna electrode 4
The voltage is related to the current flowing in (4a to 4d). In particular, since the current flowing through the antenna electrodes 4 (4a to 4d) varies depending on whether or not the seat 1 is seated and whether or not the occupant is an adult, this voltage is changed from AC to DC by the AC-DC conversion circuit 15. By converting, identifiable DC data can be obtained. This data is taken into the control circuit 18, and the sheet 1
It is possible to appropriately determine the seating status of the passengers in the vehicle. Therefore, the main problem in the conventional example shown in FIG. 9 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 airbag device 30 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 includes, for example, a first operational amplifier 16a1 and a second operational amplifier 16a.
2, first diode 16b1, second diode 16
b2 and resistors 16c1 to 16c3,
First diode 16b1 and second diode 16b2
Since the forward voltage of 1 has a negative temperature coefficient, 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 inverted by the first operational amplifier 16a1, and the level of the DC output from the smoothing circuit 17 also changes.

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 occupant is seated due to a change in the level of the DC output, making it difficult to properly 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 Vd of the AC-DC conversion circuit 15 also increases relatively, and conversely, if the amplitude of the high frequency low voltage decreases, the AC-DC conversion increases. The level of the DC output Vd of the circuit 15 also becomes relatively small. Since this level fluctuation occurs regardless of the seating condition of the occupant seated in the seat 1, when the amplitude of the high frequency low voltage fluctuates, the level of the DC output Vd of the AC-DC conversion circuit 15 is the original level. It may be larger or smaller than the 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 ninth to sixteenth inventions relate to an occupant detection system.

That is, in the first to eighth inventions relating to the object detection device, the first invention of the present invention outputs substantially sinusoidal alternating current to the antenna electrode, and a weak electric field is generated around the antenna electrode. Electric field generating means for generating,
The first frequency dividing the output frequency of the electric field generating means to 1 / n
A frequency divider circuit, and an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode,
A PLL circuit connected to the output side of the n-terminal circuit network, and a first phase detection circuit for detecting a phase difference between an output signal (original signal) of the electric field generating means and a signal (load signal) from the PLL circuit. And detecting the phase component based on the load impedance of the n-terminal circuit network to detect whether or not an object is present in the vicinity of the antenna electrode.

A second aspect of the present invention is an electric field generating means for outputting an approximately sinusoidal alternating current to the antenna electrode and generating a weak electric field around the antenna electrode, and an output of the electric field generating means. A first frequency dividing circuit for dividing the frequency into 1 / n; an n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode;
A PLL circuit connected to the output side of the terminal circuit network; a first phase detection circuit for detecting a phase difference between the output signal (original signal) of the electric field generating means and the signal (load signal) from the PLL circuit; And a control circuit that takes in a signal output from the first phase detection circuit and determines whether or not an object is present in the vicinity of the antenna electrode based on the data of this signal. By detecting a phase component based on the load impedance of, it is detected whether or not an object exists near the antenna electrode.

A third aspect of the present invention is an electric field generating means for outputting a substantially sinusoidal alternating current to the antenna electrode and generating a weak electric field around the antenna electrode, and an output of the electric field generating means. A first frequency dividing circuit for dividing the frequency into 1 / n; an n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode;
A PLL circuit connected to the output side of the terminal circuit network; a first phase detection circuit for detecting a phase difference between the output signal (original signal) of the electric field generating means and the signal (load signal) from the PLL circuit; Integrating the output signal of this first phase detection circuit,
A first integrator circuit for converting into a DC signal, and a control for taking in a signal output from the first integrator circuit and judging whether or not an object exists near the antenna electrode based on the data of this signal And a circuit. A fourth 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, and an output frequency of the electric field generating means. Of 1 / n, an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode, and a plurality of antenna electrodes A switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode through the first frequency dividing circuit and the n-terminal circuit network, and a switching circuit connected to the output side of the n-terminal circuit network. Of the PLL circuit, a first phase detection circuit for detecting a phase difference between the output signal (original signal) of the electric field generating means and the signal (load signal) from the PLL circuit, and the first phase detection circuit of the first phase detection circuit. The first that integrates the output signal and converts it to a DC signal And a control circuit for taking in a signal output from the first integrating circuit and determining whether or not an object is present in the vicinity of the antenna electrode based on the data of the signal. And

Further, a fifth invention of the present invention comprises a plurality of antenna electrodes, and an electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrodes.
A switching circuit that selectively switches / connects the electric field generating means to a specific antenna electrode among the plurality of antenna electrodes, and a plurality of detection units connected between the switching circuit and the plurality of antenna electrodes, And a control circuit for determining whether or not an object is present in the vicinity of the antenna electrode based on the data of the signal that is output from each of the detection units, and the detection unit is at least The output frequency of the electric field generating means is 1 /
a first frequency dividing circuit for dividing the frequency into n, an n terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, and an output side of the n terminal circuit network Connected PLL circuit and output signal (original signal) of the electric field generating means
And a first phase detecting circuit for detecting a phase difference between the signal (load signal) from the PLL circuit and a first integrating circuit for integrating an output signal of the first phase detecting circuit and converting it into a DC signal. It is composed of and. Furthermore, 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 a seventh invention is that the PLL circuit comprises:
At least a second terminal connected to the output side of the n-terminal network
Of the second phase detection circuit, a second integration circuit that integrates the output of the second phase detection circuit, and converts the output to a DC signal, and the second integration circuit.
Of the voltage control oscillation circuit that outputs a signal according to the output signal of the integration circuit of
and a second frequency dividing circuit which divides the frequency into a frequency of n and applies to the second phase detecting circuit, and controls so that the output frequency of the voltage controlled oscillation circuit becomes equal to the frequency of the original signal. According to an eighth invention, in the control circuit,
At least a means for storing threshold value data regarding the existence state of an object existing in the vicinity of the antenna electrode, a means for capturing a signal regarding a phase difference, and comparing the data of the captured signal with the threshold value data By doing so, it is characterized by having a judging section for judging the existence state of the object.

On the other hand, in the ninth to sixteenth inventions related to the occupant detection system, the ninth invention of the present invention is:
An antenna electrode arranged on the sheet and / or the periphery thereof,
An electric field generating means for outputting a substantially sinusoidal alternating current and generating a weak electric field around the antenna electrode, a first frequency dividing circuit for dividing the output frequency of the electric field generating means into 1 / n, and An n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, a PLL circuit connected to the output side of the n-terminal circuit network, and an output signal of the electric field generating means ( A first phase detection circuit for detecting a phase difference between the original signal) and a signal (load signal) from the PLL circuit, and a signal output from the first phase detection circuit, and based on the data of this signal And a control circuit for determining the seating condition of the occupant in the seat, and detects whether or not the occupant is seated in the seat by detecting the phase component based on the load impedance of the n-terminal circuit network. Characterized by To.

Further, a tenth 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. Means, a first frequency dividing circuit for dividing the output frequency of the electric field generating means into 1 / n, and an n terminal having two or more terminals connected between the first frequency dividing circuit and the antenna electrode. A circuit network, a PLL circuit connected to the output side of the n-terminal circuit network, and a first phase difference detection circuit for detecting the phase difference between the output signal (original signal) of the electric field generating means and the signal (load signal) from the PLL circuit. Phase detection circuit, a first integration circuit that integrates the output signal of the first phase detection circuit and converts it to a DC signal, and a signal that is output from the first integration circuit, and the data of this signal Seating of passengers on the basis of And a control circuit for determining the status, by detecting the phase component based on the load impedance of the n-terminal network, and detecting the like whether the passenger in the seat is seated.

The eleventh 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 and a first frequency dividing circuit for dividing the output frequency of the electric field generating means into 1 / n,
The n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, and the electric field generating means for a specific antenna electrode of the plurality of antenna electrodes, Frequency dividing circuit, a switching circuit for selectively switching / connecting via the n-terminal circuit network, a PLL circuit connected to the output side of the n-terminal circuit network, and an output signal (original signal) of the electric field generating means. And a first phase detecting circuit for detecting a phase difference between the signal (load signal) from the PLL circuit and a first integrating circuit for integrating an output signal of the first phase detecting circuit and converting it into a DC signal. And a control circuit that takes in a signal output from the first integration circuit and determines the seating condition of the occupant on the seat based on the data of the signal, and the switching circuit selected and switched by the switching circuit. Load-in of n-terminal network By detecting the phase component based on-impedance, and detecting the like whether the passenger in the seat is seated.

The twelfth 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 the plurality of antenna electrodes, and a plurality of switching circuits connected between the switching circuit and the plurality of antenna electrodes. Of the detection unit, and the control circuit for taking in the signals output from each of the detection units, and determining the seating status of the occupant on the seat based on the data of these signals, the detection unit, at least, A first divider circuit for dividing the output frequency of the electric field generating means into 1 / n;
An n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, a PLL circuit connected to the output side of the n-terminal circuit network, and an output signal of the electric field generating means. A first phase detection circuit for detecting a phase difference between the (original signal) and the signal (load signal) from the PLL circuit;
It is characterized in that the output signal of the first phase detection circuit is integrated and converted into a direct current signal.

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. Means, a first frequency dividing circuit for dividing the output frequency of the electric field generating means into 1 / n, and an n terminal having two or more terminals connected between the first frequency dividing circuit and the antenna electrode. A circuit network, a PLL circuit connected to the output side of the n-terminal circuit network, and a first phase difference detection circuit for detecting the phase difference between the output signal (original signal) of the electric field generating means and the signal (load signal) from the PLL circuit. Phase detection circuit, a first integration circuit that integrates the output signal of the first phase detection circuit and converts it to a DC signal, and a signal that is output from the first integration circuit, and the data of this signal Seating of passengers on the basis of A control circuit for determining the status, and an airbag device having a function of setting the airbag to a predetermined operation mode based on the determination result of the control circuit, and a phase based on the load impedance of the n-terminal circuit network. It is characterized in that the occupant's seating condition on the seat is determined by detecting the components, and the airbag of the airbag device is set to a deployable state or an undeployable state based on the determination result.

Furthermore, the 14th aspect of the present invention provides the above n
The terminal circuit network is mainly composed of a transformer having a resistor or a primary coil and a secondary coil.
In a fifth aspect of the present invention, the PLL circuit includes at least a second phase detection circuit connected to an output side of the n-terminal circuit network, and an output of the second phase detection circuit is integrated and converted into a DC signal. No. 2 integration circuit, a voltage control oscillation circuit that outputs a signal according to the output signal of this second integration circuit, and a second division circuit that divides the output frequency of this voltage control oscillation circuit into a frequency of 1 / n. And a control circuit so that the output frequency of the voltage controlled oscillation circuit becomes equal to the frequency of the original signal. The sixteenth invention is that the control circuit comprises:
At least a means for storing threshold value data regarding a seating condition of an occupant in a seat, a means for capturing a signal regarding a phase difference, and comparing the data of the captured signal with the threshold value data, the seat And a determination unit that determines a seating condition of an occupant.

[0041]

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. Note that FIG.
The same parts as those of the prior art shown in FIG. 15 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. 11, 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,
A first for dividing the output frequency of the electric field generating means 41 into 1 / n
A frequency dividing circuit 42, an n-terminal circuit network 43 having two or more terminals connected between the first frequency dividing circuit 42 and the antenna electrode 4, and arranged in the housing of the control unit 10A,
A connector 14a connected to the output side (antenna electrode side) of the n-terminal circuit network 43 and a PLL (Phase Lock Loo) connected to the output side of the n-terminal circuit network 43.
p) the circuit 44 and the electric field generating means 41 to the antenna electrode 4
By supplying an AC signal to the phase component (phase difference Pd ...
2) is the output signal (original signal) of the electric field generating means 41.
A first phase detection circuit 45 that detects a phase difference between VA and a signal (load signal) VC from the PLL circuit 44, and a phase difference signal output from the first phase detection circuit 45 are integrated into a DC signal. First integrator circuit 46 for converting, CPU, A /
D converter, external memory (eg EEPROM, RAM)
A control circuit 18 including the above, a connector 19 arranged in the housing and connected to a battery power source (not shown),
The power supply circuit 20 is connected to the connector 19. The PLL circuit 44 described above includes, for example, a second phase detection circuit 47 connected to the output side of the n-terminal network 43,
A second integration circuit 48 that integrates the output of the second phase detection circuit 47 and converts it into a DC signal, and a voltage controlled oscillator circuit 49 that outputs a signal according to the output signal of the second integration circuit 48.
And a second frequency dividing circuit 50 that divides the output frequency of the voltage controlled oscillator circuit 49 into a frequency of 1 / n, and the output frequency of the voltage controlled oscillator circuit 49 is equal to the frequency of the original signal VA. Controlled to be. These components are housed in the same housing, and the control unit 10A
Is fixed to the seat frame 3 of the seating portion 1a of the seat 1 so as not to be exposed to the seating side of the occupant. Control circuit 18 of this control unit 10A
An airbag device 30 having a configuration shown in FIG. 15, for example, is connected to the.

Such a basic system is specifically constructed, for example, as shown in FIG. The control unit 10A includes, for example, an electric field generating means 41, a first frequency dividing circuit 42, a resistor 43a and an amplifying circuit 43b, and the first frequency dividing circuit 42 and the connector 14a (antenna electrode 4).
And an n-terminal circuit network 43 connected between the n-terminal circuit network 43, a PLL circuit 44 connected to the output side of the n-terminal circuit network 43, a first phase detection circuit 45, a resistor 46a and a capacitor 46b. And a first integration circuit 46 for converting the signal from the first phase detection circuit 45 into a DC signal,
The second integration circuit 48 in the PLL circuit 44 has a resistor 48.
It is composed of a and a capacitor 48b. Note that the n-terminal circuit network 43 may be configured by only the resistor 43a by omitting the amplifier circuit 43b depending on the signal level from the electric field generating means 41.

In the control unit 10A described above, 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 to P with V (DC bias voltage) as a midpoint 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

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 near 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, it has a judgment unit for judging the occupant's seating condition).

The occupant detection system thus configured 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. The output frequency of the output voltage VA is divided by the first frequency dividing circuit 42 into 1 / n of the output frequency of the electric field generating means 41, supplied to the n-terminal circuit network 43, and output from the n-terminal circuit network 43. A voltage VB having a phase difference Pd appears on the (antenna electrode side). This high frequency output 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 currents having different phase differences flow in this manner, the n-terminal network 4
Voltages VA and VB having a phase difference Pd corresponding to the load impedance are generated on the input side and the output side of the No. 3 circuit.

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 43, The voltage VB on the load side of the n-terminal circuit network 43 has a small phase difference Pd with respect to the voltage VA on the electric field generating means side. On the other hand, sheet 1
When the occupant is seated, a large capacitance component exists around the antenna electrode 4 as compared with the stray capacitance in the empty state, and a high level current flows. 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.

On the other hand, the output signal VB of the n-terminal circuit network 43 is given to the second phase detecting circuit 47 in the PLL circuit 44, and the output signal thereof is inputted to the second integrating circuit 48, the resistor 48a and the capacitor. 48b is integrated and converted into a DC signal. The output signal of the second integrating circuit 48 is supplied to the voltage controlled oscillator circuit 49. As shown in FIG. 4B, the voltage controlled oscillator circuit 49 outputs a voltage VC having an oscillation frequency corresponding to the DC signal. This voltage VC
Is divided by the second frequency dividing circuit 50 into a frequency of 1 / n and applied to the second phase detection circuit 47. The output signal V of the n-terminal circuit network 43 is output from the second phase detection circuit 47.
A signal corresponding to the difference between the frequency of B and the frequency of the output voltage of the second frequency dividing circuit 50 is input again to the voltage controlled oscillator circuit 49 via the second integrating circuit 48. Then, the voltage controlled oscillator circuit 49 is controlled so that its oscillation frequency eliminates the above-mentioned frequency difference. That is, the frequency is controlled to be equal to the frequency of the output signal VB of the n-terminal circuit network 43 (the frequency of the output signal of the electric field generating means 41). That is, it functions as a PLL. In this way, the electric field generating means 4
1 output voltage VA and the output voltage V of the voltage controlled oscillator circuit 49
A phase difference Pd corresponding to the load impedance is provided between C and C.

Output signal (original signal) V of the electric field generating means 41
A and the output voltage VC of the voltage controlled oscillator circuit 49 in the PLL circuit 44 are supplied to the first phase detection circuit 45, and a signal corresponding to the phase difference Pd between the respective signals is output. This signal is input to the first integrating circuit 46, and the resistance 4
6a and the capacitor 46b are integrated,
It is converted into a DC signal VD as shown in (c). The first integrating circuit 46 has a function as a low-pass filter, and removes undesired noise components.

In particular, the output signal VD from the first integrating circuit 46 differs depending on the phase component based on the seating condition of the occupant, as shown in FIG. 4 (c), and is a DC signal indicated by the solid line. VD indicates the DC conversion level when the occupant is seated, and DC output VEM indicated by the dotted line indicates the DC conversion level when the occupant is seated, and there is a level difference that can be discriminated. 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 an occupant seated in the seat 1 (whether seated or not, whether 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 increases and a discriminable phase difference Pd is generated between them, and the output signal VD of the first integrating circuit 46 is shown by the solid line in FIG. It becomes the level shown by. Therefore, in FIG. 4 (c), the DC output VE in the empty state shown by the dotted line
A threshold value VSH, which is indicated by an alternate long and short dash line, regarding whether or not the occupant is seated is set between M and the DC signal VD in the seated state that is indicated by the solid line. In addition, when identifying the occupant, FIG.
The DC signal VD indicated by the solid line in FIG. 1 is subdivided into signals corresponding to adult and child occupants, and the threshold value for occupant identification is set based on these.

Therefore, the signal data VD relating to the occupant's seating status and the like fetched by the control circuit 18 are compared with the threshold value data VSH relating to the occupant's seating status and the like stored in advance in the control circuit 18, for example, the first data. When the DC output VD from the integration circuit 46 of 1 is larger than the threshold value VSH relating to 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. 15 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 switching elements SW1 and SW2 are set so that the gate signal is supplied.

According to this embodiment, the first phase detection circuit 45 outputs the output signal VA of the electric field generating means 41 and the PLL circuit 4.
The phase difference Pd is detected by using the signal VC from the signal No. 4 and the phase difference Pd.
If the frequency of the AC output from the electric field generating means 41 is constant, it will be 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 output signal (original signal) of the electric field generating means 41 is frequency-divided by the first frequency dividing circuit 42 into 1 / n and supplied to the antenna electrode 4 via the n-terminal circuit network 43. At the same time, the signal VB whose phase is changed by the load impedance of the antenna electrode 4 is input to the PLL circuit 44. This signal is applied to the voltage controlled oscillation circuit 49 via the second phase detection circuit 47 and the second integration circuit 48 in the PLL circuit 44, and the oscillation frequency of the voltage controlled oscillation circuit 49 becomes equal to the frequency of the original signal. And the oscillation signal is frequency-divided by the second frequency-dividing circuit 50.
Is fed back to the phase detection circuit 47. As a result, the phase difference between the original signal and the output signal of the voltage controlled oscillator circuit 49 whose phase has changed due to the load on the n-terminal circuit network 43 can be detected with a higher order component of n times, so that the occupant's seating condition It is possible to accurately detect (the existence state of the object).

In particular, the output signal of the first phase detection circuit 45 is converted into a DC signal by the first integration circuit 46, and an undesired noise component is removed by the low-pass filter function of the first integration circuit 46. To be performed, the control circuit 18
The comparison / determination process with the threshold value can be performed accurately.

Further, the control unit 10A has an electric field generating means 41, a first frequency dividing circuit 42, an n-terminal circuit network 43, a PLL circuit 44, a first phase detecting circuit 45, a first integrating circuit 46, in the same housing. Since the circuit elements such as the control circuit 18 and the power supply circuit 20 are housed in a compact structure, it can be easily incorporated into the seat 1. 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 air bag of the air bag device 30 can be set to either the inflatable state or the inflatable state based on the judgment of whether the occupant is an adult or a child. For example, when it is determined that the occupant is a child based on the level of the DC output of the first integration circuit 46, 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.
The basic circuit configuration is the same as that of the first embodiment shown in FIG. The difference is that the n-terminal circuit network 43A is composed of a resistor 43a, an amplifier circuit 43b, and a transformer 43c. This transformer 43c is configured by winding, for example, a primary coil and a secondary coil around a ring core. The primary coil (input side) has an electric field generating means 41, and the secondary coil (output side) has a resistor 43a and an amplifier. The antenna electrodes 4 are connected to each other via the circuit 43b. The resistor 43a and the amplifier circuit 43b may be omitted depending on the winding ratio between the primary coil and the secondary coil of the transformer 43c.

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 43c, so that it is possible to reduce the cost by simplifying the circuit configuration of the electric field generating means 41.

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 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 51 having a plurality of switching means 51a to 51d is connected to the antenna electrode 4 (4a to 4d). Incidentally, the switching means 51a of the switching circuit 51
.About.51d are appropriately switched / 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 selected by the switching circuit 51 are transmitted. It can be taken into the control circuit 18 via the PLL circuit 44, the first phase detection circuit 45, and the first integration circuit 46. 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. 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 difference is that the first frequency dividing circuit 42, the n-terminal circuit network 43, the PLL circuit 4
4, a plurality of detection units Da to Dd including a first phase detection circuit 45 and a first integration circuit 46 are connected to the connectors 14a to 14a.
14d is connected to the plurality of antenna electrodes 4 (4a to 4d), and the switching circuit 51 is connected between the electric field generating means 41 and the plurality of detection units Da to Dd. The detection units Da to Dd have the same configuration. According to this embodiment, the same effect as the embodiment shown in FIG. 1 (FIG. 3) and FIG. 6 can be obtained.

Particularly, if the antenna electrode 4 is arranged on the dashboard or the door or the side support portion of the seat 1,
For example, it is possible to detect that the passenger in the passenger seat has fallen asleep and the interval between them has become narrower than necessary, and the deployment operation of the airbag device 30 or the side airbag device can be stopped. Instead, it is possible to detect whether or not the occupant is properly seated.

The present invention is not limited to the above-described embodiment but is applied to, for example, detecting the seating status of a passenger on a seat, and also detects the existence status of any dielectric object. Can be applied to the device.
Therefore, depending on the application, the device may be an antenna electrode, an electric field generating means, a 1 / n frequency dividing circuit, an n terminal circuit network, a PLL circuit,
It can also be configured by a phase detection 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 can be set to a value other than 125 KHz, and the voltage thereof can be 3 VP or higher. 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 antenna electrodes can be increased or decreased as appropriate,
The shape can be formed in a rectangular shape, a band shape, a ring shape, a spiral shape, etc. in addition to the square shape, and the antenna electrode portion arranged on the base member can be covered with an insulating cover 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.

[0066]

As described above, according to the present invention, the first phase detecting circuit outputs the output signal (original signal) of the electric field generating means and the P signal.
Since the phase difference is detected by using the signal (load signal) from the LL circuit, if the frequency of the AC output from the electric field generating means is constant, the phase difference is AC. Even if the output amplitude fluctuates, it does not affect the phase component. Therefore, even if the amplitude of the AC output from the electric field generating means fluctuates due to the power supply fluctuation, the phase component based on the load impedance is kept substantially constant, and as a result, the existence condition of the object (or the seating condition of the occupant) is accurately determined. In addition, the cost of the system or device can be reduced.

Further, the frequency of the output signal of the electric field generating means is divided by the first dividing circuit, and the frequency of the output signal of the PLL circuit is divided by the second dividing circuit.
Phase detection circuit, second integrator circuit, voltage controlled oscillator circuit,
Since the first phase detection circuit is composed of the second frequency divider circuit and has the PLL function, the first phase detection circuit detects the phase difference between the original signal and the output signal of the voltage controlled oscillation circuit whose phase is changed by the load of the n-terminal network. It becomes possible to detect with n times higher order components. Therefore, it is possible to improve the detection accuracy of the presence status of the object (or the seating status of the occupant). In particular, when applied to an occupant detection system equipped with an airbag device, the airbag device can be operated appropriately.

Further, if the output signal of the first phase detection circuit is configured to be integrated by the first integration circuit,
Since the undesired noise component can be removed by the low-pass filter function of the first integrator circuit, highly reliable judgment processing in the control circuit becomes 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 of an electric field generating means and a PLL circuit.

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 waveform diagram of the output voltage of the electric field generating means, and FIG. 4B is voltage controlled oscillation in the PLL circuit. FIG. 3C is a waveform diagram of the output voltage of the circuit, and FIG. 7C is a diagram showing the output voltage of the first integrating circuit.

FIG. 5 is an electric circuit diagram showing a second embodiment of an occupant detection system (object detection device) according to the present invention.

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 of an airbag device according to a conventional example.

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

10A and 10B are views for explaining the basic operation of the occupant detection system according to the prior art, where FIG. 10A is a diagram showing an electric field distribution around the antenna electrode, and FIG. It is a figure which shows the electric field distribution when an object exists in the vicinity.

11A and 11B are views showing a seat portion of an occupant detection system according to a prior art, wherein FIG. 11A is a side view showing an arrangement state of antenna electrodes on the seat, and FIG. ) Is a plan view of FIG.

12 is a specific configuration diagram of the antenna electrode shown in FIG. 11, FIG. 12 (a) is a plan view, and FIG. 12 (b) is FIG. 12 (a).
Is a sectional view taken along line X-X, and FIG. 6C is a sectional view taken along line Y-Y in FIG.

FIG. 13 is an electric circuit diagram of an occupant detection system according to the prior art.

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

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

16A and 16B are diagrams for explaining the operation of the control unit shown in FIG. 13, where FIG. 16A is a waveform diagram of the line voltage of the transmission system, and FIG. 16B is an output voltage of the full-wave rectifier circuit. FIG. 3C is a diagram showing the output voltage of the smoothing circuit.

FIG. 17 is a diagram for explaining a seated state of an occupant on a seat, FIG. 17A is a diagram showing an adult's seated state, and FIG. 17B is a diagram showing a child's seated state.

[Explanation of symbols]

1 sheet 1a Seating section 1b Backrest 2 base 3 seat frame 4 antenna electrodes 4a-4d Antenna electrode part 5 Base member 6 (6a-6d) Lead wire 10, 10A control unit 11 Electric field generating means (oscillation circuit) 12 resistance 13 Switching circuit 13a to 13d switching means 14a to 14d connectors 15 AC-DC conversion circuit 16 Full-wave rectifier circuit 16a1 First operational amplifier 16a2 Second operational amplifier 16b1 first diode 16b2 second diode 16c1 to 16c3 resistance 17 Smoothing circuit 17a resistance 17b capacitor 18 Control circuit 19 connector 20 power circuit 30 airbag device 41 Electric field generating means 42 First Frequency Divider 43, 43A n terminal network 43a resistance 43b amplifier circuit 43c transformer 44 PLL circuit 45 First Phase Detection Circuit 46 First integrating circuit 46a resistance 46b capacitor 47 Second Phase Detection Circuit 48 Second integrating circuit 48a resistance 48b capacitor 49 Voltage controlled oscillator 50 Second frequency divider 51 Switching circuit 51a-51d 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 oscillator circuit OB object P adult crew SP Child crew

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01V 3/08 B60N 2/44 B60R 21/32 G01V 3/10

Claims (16)

(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 an output frequency of the electric field generating means is divided into 1 / n. A first frequency divider circuit, an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode, and a PLL circuit connected to the output side of the n-terminal circuit network A first phase detection circuit for detecting a phase difference between an output signal (original signal) of the electric field generating means and a signal (load signal) from the PLL circuit, and a load impedance of the n-terminal network is provided. An object detection device, which detects whether or not an object exists near the antenna electrode by detecting a phase component based on the detected phase component. 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 an output frequency of the electric field generating means is divided into 1 / n. A first frequency divider circuit, an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode, and a PLL circuit connected to the output side of the n-terminal circuit network A first phase detecting circuit for detecting a phase difference between an output signal (original signal) of the electric field generating means and a signal (load signal) from the PLL circuit, and a signal output from the first phase detecting circuit And a control circuit for determining whether or not an object exists near the antenna electrode based on the data of this signal, and detecting a phase component based on the load impedance of the n-terminal network. , Said Anne An object detection device, which detects whether or not an object exists near the tenor electrode. 3. An electric field generating means for outputting an almost sinusoidal alternating current to the antenna electrode and generating a weak electric field around the antenna electrode, and an output frequency of the electric field generating means is divided into 1 / n. A first frequency divider circuit, an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode, and a PLL circuit connected to the output side of the n-terminal circuit network A first phase detection circuit for detecting a phase difference between an output signal (original signal) of the electric field generating means and a signal (load signal) from the PLL circuit, and integrating an output signal of the first phase detection circuit Then, the first integrator circuit for converting into a DC signal and the signal output from the first integrator circuit are taken in, and it is judged whether or not an object exists near the antenna electrode based on the data of this signal. And a control circuit for Object detection device to collect. 4. A plurality of antenna electrodes, an electric field generating means for generating a weak electric field around the antenna electrodes by outputting a substantially sinusoidal alternating current, and an output frequency of the electric field generating means divided into 1 / n. A first frequency divider circuit that circulates, an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode, and a specific antenna electrode among the plurality of antenna electrodes A switching circuit for selectively switching and connecting the electric field generating means via the first frequency dividing circuit and the n-terminal circuit network; a PLL circuit connected to the output side of the n-terminal circuit network; A first phase detecting circuit for detecting a phase difference between an output signal (original signal) of the electric field generating means and a signal (load signal) from the PLL circuit, and an output signal of the first phase detecting circuit are integrated, A first integrator circuit that converts to a DC signal, and Object detection circuit that takes in a signal output from the first integration circuit of the device and determines whether an object exists in the vicinity of the antenna electrode based on the data of the signal. apparatus. 5. A plurality of antenna electrodes, an electric field generating means for outputting a substantially sinusoidal alternating current to generate a weak electric field around the antenna electrodes, and a specific antenna electrode among the plurality of antenna electrodes. A switching circuit for selectively switching / connecting the electric field generating means, a plurality of detection units connected between the switching circuit and the plurality of antenna electrodes, and capturing signals output from the respective detection units, And a control circuit for determining whether or not an object is present in the vicinity of the antenna electrode based on the data of the signal, wherein the detection unit divides at least the output frequency of the electric field generating means into 1 / n. A first frequency divider circuit that circulates, an n-terminal circuit network having two or more terminals connected between the first frequency divider circuit and the antenna electrode, and an output side of the n-terminal circuit network. A continuous PLL circuit, a first phase detecting circuit for detecting a phase difference between a signal (original signal) from the electric field generating means and a signal (load signal) from the PLL circuit, and the first phase detecting circuit. And a first integrator circuit that integrates the output signal of the above and converts it into a DC signal. 6. The object detecting device according to claim 1, wherein the n-terminal circuit network is mainly composed of a transformer having a resistor or a primary coil and a secondary coil. 7. The PLL circuit comprises at least the n
A second phase detection circuit connected to the output side of the terminal network;
A second integration circuit that integrates the output of the second phase detection circuit and converts it into a DC signal, a voltage control oscillation circuit that outputs a signal according to the output signal of the second integration circuit, and this voltage control The output frequency of the oscillating circuit is divided into a frequency of 1 / n and a second frequency dividing circuit is provided to the second phase detecting circuit. The output frequency of the voltage controlled oscillating circuit is the frequency of the original signal. The object detection device according to any one of claims 1 to 5, wherein the object detection device is controlled to be equal to. 8. The control circuit stores, at least, threshold value data relating to a state of existence of an object existing in the vicinity of the antenna electrode, a means for fetching a signal relating to a phase difference, and a means for fetching the fetched signal. The object detection device according to claim 2, further comprising a determination unit configured to determine the presence status of an object by comparing the data with the threshold value data. 9. An electric field generating means for outputting a substantially sinusoidal alternating current to generate a weak electric field around the antenna electrode and an antenna electrode arranged on the sheet and / or its periphery, and an output of this electric field generating means. A first frequency dividing circuit for dividing the frequency into 1 / n, an n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, and the n-terminal circuit network A PLL circuit connected to the output side of the, the output signal (original signal) of the electric field generating means and the PL
A first phase detection circuit that detects a phase difference from a signal (load signal) from the L circuit, and a signal output from the first phase detection circuit is taken in, and an occupant on a seat based on the data of the signal. And a control circuit for determining the seating status of the vehicle, and detects whether or not the occupant is seated in the seat by detecting the phase component based on the load impedance of the n-terminal circuit network. Occupant detection system. 10. An electric field generating means for outputting a substantially sinusoidal alternating current to generate a weak electric field around the antenna electrode and an antenna electrode arranged on the sheet and / or its periphery, and an output of the electric field generating means. A first frequency dividing circuit for dividing the frequency into 1 / n, an n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, and the n-terminal circuit network A PLL circuit connected to the output side of the, the output signal (original signal) of the electric field generating means and the PL
A first phase detection circuit that detects a phase difference from a signal (load signal) from the L circuit, a first integration circuit that integrates the output of the first phase detection circuit, and converts the output to a DC signal; A control circuit for taking in a signal output from the first integrator circuit and judging the seating condition of the occupant on the seat based on the data of the signal, and calculating a phase component based on the load impedance of the n-terminal circuit network. An occupant detection system, which detects whether or not an occupant is seated in the seat by detecting the occupant. 11. A sheet and / or a plurality of antenna electrodes 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, and the electric field generating means. A first frequency dividing circuit for dividing the output frequency of 1 to 1 / n, an n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, A switching circuit for selectively switching / connecting the electric field generating means to a specific antenna electrode among the antenna electrodes via the first frequency dividing circuit and the n-terminal circuit network, and an output of the n-terminal circuit network. PL connected to the side
An L circuit, a first phase detecting circuit for detecting a phase difference between an output signal (original signal) of the electric field generating means and a signal (load signal) from the PLL circuit, and an output of the first phase detecting circuit. A first integrator circuit that integrates a signal and converts it into a DC signal, and a control circuit that takes in the signal output from this first integrator circuit and determines the seating status of the occupant on the seat based on the data of this signal And detecting the phase component based on the load impedance of the n-terminal circuit network switched / selected by the switching circuit to detect whether or not the occupant is seated in the seat. Occupant detection system. 12. A plurality of antenna electrodes arranged on a sheet and / or its periphery, 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. Of the electrodes, a switching circuit for selectively switching and connecting the electric field generating means to a specific antenna electrode; a plurality of detection units connected between the switching circuit and the plurality of antenna electrodes; And a control circuit for determining a seating condition of an occupant on the seat based on the data of the signal output from the unit, wherein the detection unit is at least 1 / the output frequency of the electric field generating means. a first frequency dividing circuit for dividing the frequency into n, an n terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, and an n terminal circuit The PLL circuit connected to the output side of the road network, the output signal (original signal) of the electric field generating means, and the PL
From a first phase detection circuit that detects the phase difference from the signal (load signal) from the L circuit and a first integration circuit that integrates the output signal of this first phase detection circuit and converts it to a DC signal An occupant detection system characterized by being configured. 13. An electric field generating means for outputting a substantially sinusoidal alternating current to generate a weak electric field around the antenna electrode and an antenna electrode arranged on the sheet and / or its periphery, and an output of the electric field generating means. A first frequency dividing circuit for dividing the frequency into 1 / n, an n-terminal circuit network having two or more terminals connected between the first frequency dividing circuit and the antenna electrode, and the n-terminal circuit network A PLL circuit connected to the output side of the, the output signal (original signal) of the electric field generating means and the PL
A first phase detection circuit that detects a phase difference from a signal (load signal) from the L circuit, a first integration circuit that integrates the output of the first phase detection circuit, and converts the output to a DC signal; A control circuit that takes in the signal output from the first integrator circuit and determines the seating status of the occupant on the seat based on the data of this signal, and sets the airbag to a predetermined operation mode based on the determination result of this control circuit. An air bag device having a function capable of being set to, and determining the seating condition of the occupant on the seat by detecting the phase component based on the load impedance of the n-terminal circuit network, and based on the result of the determination, An occupant detection system, wherein an airbag of an airbag device is set to a deployable state or an undeployable state. 14. The occupant detection system according to claim 9, wherein the n-terminal circuit network is mainly composed of a transformer having a resistor or a primary coil and a secondary coil. 15. The PLL circuit includes at least a second phase detection circuit connected to the output side of the n-terminal circuit network, and a second phase detection circuit for integrating an output of the second phase detection circuit and converting the output to a DC signal. No. 2 integration circuit, a voltage-controlled oscillation circuit that outputs a signal according to the output signal of this second integration circuit, and the output frequency of this voltage-controlled oscillation circuit is divided into a frequency of 1 / n. 14. A second frequency dividing circuit provided to the phase detecting circuit according to claim 9, wherein the output frequency of the voltage controlled oscillator circuit is controlled to be equal to the frequency of the original signal. The occupant detection system described in Crab. 16. 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. 14. A determination unit that determines the seating status of an occupant in a seat by comparing the value data with the value data.
The occupant detection system according to any one of 1.