JP2000071931A - Occupant detection system and antenna electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an occupant detection system and an antenna electrode capable of effectively reducing the cost of a control unit and improving even productivity, in addition to the formation of an antenna electrode under the application of relatively simple constitution. SOLUTION: This antenna electrode 4 is applied to an occupant detection system constituted so that electric field is generated around the antenna electrode 4 laid on a sheet 1 and information related to current flowing across the antenna electrode 4 is detected on the basis of the generated electric field. In addition, the system is constituted so that the seated status or the like of an occupant on a seat is judged on the basis of the obtained information. In this case, the antenna electrode 4 is formed out of antenna electrode parts 4A to 4F by directly attaching a conductive member to a base member 5 made of an insulation material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an occupant detection system and an antenna electrode, and more particularly to a state in which an airbag of an airbag device can be deployed in accordance with the occupant's seating state in a passenger seat of an automobile equipped with the airbag device. Also, the present invention relates to an improvement in an occupant detection system and an antenna electrode which can be set to a state in which deployment is impossible.

[0002]

2. Description of the Related Art The applicant of the present invention has previously proposed an occupant detection system in which antenna electrodes are arranged on a sheet and an electric field generated by the antenna electrodes is disturbed. The basic principle of the occupant detection system will be described with reference to FIG. First, FIG.
As shown in (1), when a high-frequency low voltage from the oscillation circuit OSC is applied to the antenna electrode E, a weak electric field is generated around the antenna electrode E. As a result, a current I flows on the antenna electrode E side. In this state, when an object OB is present near the antenna electrode E as shown in FIG. 4B, a disturbance occurs in the electric field, and a current I ₁ different from the current I is present on the antenna electrode E side. Will flow.

[0003] Therefore, depending on whether the object OB is on or off the vehicle seat, the antenna electrode E
A change occurs in the current flowing to the side of the vehicle, and by utilizing this phenomenon, it is possible to detect the occupant's seating state on the seat and the like. When the object OB is on the sheet, the current flowing to the antenna electrode E increases, and when the object OB is not on the sheet, the current flowing to the antenna electrode E decreases. I do.

A specific example of an occupant detection system utilizing this principle will be described with reference to FIGS. FIG.
Reference numeral 1 denotes a passenger seat (or driver's seat), and the seat 1 mainly includes a seating portion 1a and a backrest portion 1b. The seat 1a includes, for example, a seat frame 3 fixed to a base 2 slidable back and forth,
The backrest 1b includes a cushioning material arranged on the top of the toe frame 3 and an exterior material covering the cushioning material. It is configured by covering a material with an exterior material. In particular, a plurality of strip-shaped antenna electrodes 4 (4a to 4f) are arranged on the backrest 1b so as to be separated from each other in a substantially horizontal state in the vertical direction, and to be located over a wide range in the width direction of the backrest 1b. Have been. still,
A control unit 10, which will be described later, is arranged in or near the sheet frame 3.

As shown in FIG. 12, for example, a base member 5 made of an insulating material such as a nonwoven fabric is used as the antenna electrode 4.
And band-shaped antenna electrode portions 4a to 4f of substantially the same size, which are vertically spaced apart from each other on one surface of the base member 5 by a predetermined distance, and leads derived from the antenna electrode portions 4a to 4f. 6 (6a to 6f).
In particular, the antenna electrode portions 4a to 4f are formed by weaving a conductive cloth or a thread-like metal wire or a conductive fiber into the cloth surface. In addition, the lead wire 6 (6a ~
The lead-out end of 6f) is connected to connectors (or terminals) 19a to 19f of the control unit 10 described later.

As shown in FIG. 13, for example, the control unit 10 includes an interface circuit A, connectors 19a to 19f arranged in a housing, a CPU and an A / D converter.
A control circuit 20 including a conversion unit, an external memory (for example, EEPROM and RAM), a connector 21 arranged in the housing and connected to a battery power supply (not shown), and a connector 21 connected to the connector 21 and having an interface circuit A, And a power supply circuit 22 for generating an appropriate Vcc power supply required by the control circuit 20 and the like. This control unit 1
For example, an airbag device 30 having a configuration shown in FIG.

In the above control unit 10, the interface circuit A comprises an electric field generating means for generating a weak electric field around the antenna electrode 4 by a high frequency low voltage having a frequency of about 120 kHz and a voltage of about 5 to 12 V, for example. (For example, an oscillation circuit) 11 and an amplitude control circuit 12 for controlling the voltage amplitude of the transmission signal from the oscillation circuit 11 to be substantially constant.
A current detection circuit (information detection circuit) 15 for detecting a transmission current of a transmission signal; an AC-DC conversion circuit 16 for converting an output signal of the current detection circuit 15 into a direct current; and an output signal of the AC-DC conversion circuit 16 17 connected to the current detection circuit 15 and the other to the connectors 19a to 19f, respectively.
Switching circuit 1 for antenna electrode portions 4a to 4f having 18f
And 8. Incidentally, the selective switching of the switching means 18a to 18f in the switching circuit 18 is performed based on a signal from the control circuit 20.

In this interface circuit A, the amplitude control circuit 12 comprises, for example, an amplitude variable circuit 13 for varying the voltage amplitude of the transmission signal and an amplitude detection circuit 14 for detecting the voltage amplitude of the transmission signal. ing. The amplitude variable circuit 13 includes an amplitude variable section 13a including, for example, a programmable gain amplifier (PGA). The amplitude detection circuit 14 includes a voltage amplitude detection section 14a including, for example, an operational amplifier and a voltage amplitude detection section 14a. An AC-DC conversion circuit 14b for converting an output signal into a direct current;
Amplifier 14c for amplifying the output signal of DC conversion circuit 14b
It is composed of The output signal of the amplifier 14c is supplied to the control circuit 20, and the variable amplitude signal for the variable amplitude section 13a is output from the control circuit 20.

In the interface circuit A, the current detecting circuit 15 is, for example, an impedance element such as a resistor 15a connected in series to a circuit (transmission signal system).
And an amplifier 15b such as a differential amplifier for amplifying the terminal voltage of the resistor 15a. The output side of the current detection circuit 15 is connected to a control circuit 20 via an AC-DC conversion circuit 16 and an amplifier 17. The output side of the resistor 15 a in the current detection circuit 15 is connected to the switching circuit 18.
Are connected to connectors 19a to 19f via switching means 18a to 18f.

The above-described airbag device 30 is, for example, a
A squib circuit on the driver's seat side composed of a series circuit of a switching element SW1 such as a finning sensor SS1, a squib SQ1, and a field effect transistor, and a squib circuit on the passenger side composed of a series circuit of a self-sensoring sensor SS2, a squib SQ2, and a switching element SW2. A squib circuit, an electronic acceleration sensor (collision detection sensor) GS, and a function of determining the presence or absence of a collision based on the output signal of the electronic acceleration sensor GS and supplying a signal to the gates of the switching elements SW1 and SW2. And a control circuit CC.

The occupant detection system thus configured operates as follows. First, when a high-frequency low voltage is transmitted from the oscillation circuit 11, the voltage amplitude thereof is detected by the detection unit 14a of the amplitude detection circuit 14, and the detection signal is A
The direct current is converted by the C-DC conversion circuit 14b to the
The signal is amplified at 4c and input to the control circuit 20. The control circuit 20 determines whether or not the detected voltage amplitude has a predetermined amplitude value, and outputs an amplitude variable signal for correcting the detected voltage amplitude to the predetermined voltage amplitude to the amplitude variable section 13a. Thereby, the voltage amplitude of the transmission signal is corrected to a predetermined amplitude,
Thereafter, the amplitude is controlled to be constant by the cooperative operation of the amplitude variable circuit 13 and the amplitude detection circuit 14.

The transmission signal having the constant voltage amplitude is supplied to the antenna electrodes 4a to 4f via the current detection circuit 15, the switching circuit 18, and the connectors 19a to 19f, and as a result, the periphery of the antenna electrodes 4a to 4f. Generates a weak electric field. At this time, the switching means 18a to 18f of the switching circuit 18 are controlled to open and close by a signal from the control circuit 20, and only the switching means 18a is first closed, and then only the switching means 18b is closed,
In the same manner, switching control is selectively performed so that only specific switching means are sequentially closed and other switching means are opened at the same time. Therefore, when the specific switching means (18a to 18f) is closed, the transmission signal having the constant voltage amplitude is output from the current detection circuit 1
(5) Specific switching means (18a to 18f) and specific connectors (19a to 19f) are supplied to specific antenna electrode units (4a to 4f) via specific connectors (19a to 19f). As a result, specific antenna electrode units (4a to 4f) A weak electric field is generated around the vehicle, and a current flows according to the difference in the contact area (opposed area) with the seat (antenna electrode portion) such as the occupant's back, shoulder, neck, and head. This current is detected by the current detection circuit 15, converted into a direct current by the AC-DC conversion circuit 16, amplified by the amplifier 17, and input to the control circuit 20 one after another.

The control circuit 20 stores in advance threshold values (threshold data) relating to whether or not the occupant is seated, identification of the occupant (discrimination as an adult or a child), and the like. For example, regarding whether or not the occupant is seated, the level of the current flowing through the antenna electrode portions 4a to 4f is higher in the occupant's seat state than in the vacant seat state. It is set based on whether or not.
Regarding the identification of the occupant, a characteristic current flows through the antenna electrode portions 4a to 4f by an adult and a child, and the current level is large. Set as a reference.

Accordingly, various kinds of arithmetic processing are performed on actual signal data relating to currents flowing through the plurality of antenna electrode portions 4a to 4f taken into the control circuit 20. For example, actual signal data is stored in advance as to whether the occupant is seated,
It is compared with threshold data relating to the identification of the occupant, and it is determined whether or not the occupant is seated on the sheet, whether the occupant seated on the sheet is an adult or a child, and the like. Is done. Based on the determination result, the airbag device 30 shown in FIG. 14 is set so that the airbag can be deployed or cannot be deployed by the transmission signal from the control circuit 20. That is, the transmission signal from the control circuit 20 is input to the control circuit CC of the airbag device 30, and when the occupant is a child, the occupant does not supply a signal to the gate of the switching element SW2 on the passenger seat side. In the case of an adult, it is set so as to supply a signal to the gate of the switching element SW2. Therefore, when the vehicle collides for some reason, the passenger-side airbag is not deployed when the occupant is a child, but is deployed when the occupant is an adult. The airbag on the driver's seat side is deployed regardless of the situation on the passenger's seat side.

[0015]

According to the occupant detection system configured as described above, a weak electric field is selectively generated in the plurality of antenna electrode portions 4a to 4f arranged on the sheet 1, thereby enabling an antenna to be detected. Since a characteristic current corresponding to an adult or child occupant flows through the electrode portions 4a to 4f, a signal related to this current is taken into the control circuit 20 to be subjected to arithmetic processing and compared with threshold data and the like. This makes it possible to accurately determine whether or not the occupant is seated on the seat, identify the occupant, and the like. Therefore, when a child occupant is seated on the seat, the deployment of the airbag can be prevented beforehand, and desirable control of the airbag device 30 becomes possible.

However, recently, there has been a strong demand for cost reduction for such occupant detection systems. For example, in the antenna electrode 4, a plurality of antenna electrode portions (4
a to 4f) are formed by weaving a conductive cloth or a thread-like metal wire or a conductive fiber into the cloth surface in consideration of the ride comfort of the occupant. It tends to be higher.

In addition, the antenna electrode 4 is formed by applying an adhesive such as hot melt to the back surfaces of the plurality of antenna electrode portions 4a to 4f made of conductive cloth, and then applying the adhesive to the antenna electrode portions 4a to 4f.
The antenna electrodes 4a to 4f are fixed to the base member 5 by heat-treating the antenna electrodes 4a to 4f while pressing the antenna electrodes 4a to 4f. Although it is manufactured, application of an adhesive to the antenna electrode portions 4a to 4f or the antenna electrode portions 4a to 4f
Since the arrangement of f on the base member 5 is manually performed, the antenna electrode portions 4a to 4a are not used in a mass production line.
4f and the base member 5 in a predetermined positional relationship,
As a result of requiring a great deal of man-hour to adjust the interval between the antenna electrode portions to a predetermined interval, there is a problem that work efficiency is significantly impaired and it is difficult to increase productivity.

Therefore, an object of the present invention is to provide an occupant detection system and an antenna electrode which can effectively reduce the cost of the control unit as well as the antenna electrode with a relatively simple configuration and improve the productivity. To provide.

[0019]

SUMMARY OF THE INVENTION Accordingly, in order to achieve the above-mentioned object, the present invention is to arrange an antenna electrode on a sheet and / or its periphery, and generate an electric field around this antenna electrode. An occupant detection system configured to detect information data related to a current flowing through an antenna electrode based on the electric field, and to determine a seating state of the occupant on the sheet based on the information, The antenna electrode,
An antenna electrode portion is formed by directly attaching a conductive member to a base member made of an insulating member.

[0020] The second invention of the present invention relates to a sheet and / or sheet.
Alternatively, an antenna electrode is disposed around the antenna electrode, an electric field is generated around the antenna electrode, information data related to a current flowing through the antenna electrode is detected based on the electric field, and a sheet is detected based on this information. An occupant detection system configured to determine a seating state of an occupant in the airbag device and to set an airbag of an airbag device to a predetermined operation mode based on the determination result. An antenna electrode portion is formed by directly applying a conductive member to a base member made of a member.

The third invention of the present invention relates to a sheet and / or
Alternatively, an electric field is generated around an antenna electrode disposed therearound, and information related to a current flowing through the antenna electrode is detected based on the electric field, and based on the information, an occupant is seated in a seat. An antenna electrode applied to an occupant detection system configured to judge whether the antenna electrode portion is formed by directly applying a conductive member to a base member made of an insulating member. It is characterized by having comprised it.

The fourth invention of the present invention relates to a sheet and / or
Alternatively, an electric field is generated around an antenna electrode disposed therearound, and information related to a current flowing through the antenna electrode is detected based on the electric field, and based on the information, an occupant is seated in a seat. An antenna electrode applied to an occupant detection system configured to judge whether the antenna is at least a base made of an insulating member.
An antenna electrode portion made of a conductive member directly attached to a desired portion of the base member; and a lead derived from the antenna electrode portion and having an electrical connection with the antenna electrode portion. And a line.

Furthermore, in a fifth aspect of the present invention, the antenna electrode portion is formed in an appropriate shape such as a loop shape including a band shape, a spiral shape, a meandering shape, a comb tooth shape, and a radial shape by using a conductive member. According to a sixth aspect of the present invention, the antenna electrode portion is formed by screen printing, spraying, or the like on a conductive member.
The seventh aspect of the present invention is characterized in that it is formed in a suitable shape such as a loop shape including a band shape, a spiral shape, a meandering shape, a comb tooth shape, a radial shape by any of coating, vapor deposition, and plating.
A hole is formed in a part of the base member, and a conductive member is directly applied to a desired portion of the base member including the hole to form an antenna electrode portion. The wire is electrically and mechanically connected by connecting means using a hole, and in the eighth invention, the conductive member comprises:
It contains at least a conductive filler, a binder mainly composed of a resin, and a solvent, and is characterized by being subjected to a heat treatment after being formed on an antenna electrode portion by being attached to a base member.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of an antenna electrode applied to an occupant detection system according to the present invention will be described with reference to FIGS. 11 to 12.
Are given the same reference numerals as in the prior art shown in FIG. In FIG. 1, an antenna electrode 4 is disposed on a backrest 1b of a sheet 1 so as to be located between a cushion material and an exterior material. The antenna electrode 4 includes, for example, a spanboard (a type of nonwoven fabric),
A base member 5 made of an insulating member such as a cloth material including a nonwoven fabric or a woven fabric, a paper material, a laser, a plastic film, a film-like rubber material, and a desired portion of one surface of the base member 5 A plurality of antenna electrode portions 4A to 4F made of a conductive member directly attached, and lead wires derived from the antenna electrode portions 4A to 4F and having an electrical connection with the antenna electrode portions 4A to 4F. (Not shown).

In the above-described antenna electrode 4, the conductive member forming the antenna electrode portions 4A to 4F is, for example, a matrix (also referred to as a binder) of a polymer material.
Metals (silver, copper, carbon, etc.) and metal oxides, carbon black, graphite and other conductive fine particles (conductive filler) are dispersed and suspended to form a liquid with appropriate viscosity. Depending on the situation, a dispersant or the like for improving the dispersibility of the conductive filler may be used. This conductive member is usually a non-conductor in a liquid state, but the conductive fillers come into contact with each other by a thermosetting treatment,
It has the property that many chain-like conductive paths are formed. As the matrix (binder), for example, an epoxy resin, a phenol resin, a polyimide resin, a silicon resin, a resin obtained by modifying an epoxy resin with silicon, and the like are preferable, and an epoxy resin and a silicon resin are recommended.

The antenna electrode portions 4A to 4C made of this conductive member
The formation of the 4F is recommended by a printing method using a screen printing apparatus, but it can also be formed by spraying and applying using a mask member for masking a portion other than the portions to be the antenna electrode portions 4A to 4F. In addition to such conductive members,
It can also be formed by vapor deposition or plating using a metal such as aluminum, nickel, or copper. In the illustrated example, the antenna electrode portions 4A to 4F are formed in a band shape, but may be formed in an appropriate shape such as a loop shape including a spiral shape, a meandering shape, a comb tooth shape, and a radial shape depending on circumstances. It is possible.

The above-mentioned antenna electrode 4 is manufactured by, for example, a manufacturing unit shown in FIG. In FIG.
Reference numeral 1 denotes a roll in which a long base member 5 is wound.
It is configured to be taken up by the other take-up roll R2 via a feed roller. The moving path of the base member 5 is provided with a screen printing process and a heat treatment process. In this screen printing process, a screen printing device P is used.
R is arranged. As shown in FIG. 1B, the screen printing apparatus PR is, for example, a rectangular frame W and a silk screen stretched over the frame W and formed with a printing pattern of the antenna electrode portions 4A to 4F. And a squeegee SG for moving a carbon paste CP containing a liquid conductive member such as carbon powder, epoxy resin, and solvent. A heating furnace H is provided in the heat treatment step, and is set at a temperature of, for example, about 150 to 200 ° C.

First, when a desired portion of the base member 5 is transferred onto the stage ST and stopped, the screen printing device PR is lowered and placed on the base member 5. In this state, when the squeegee SG is moved in the direction of the arrow shown in the figure while pressing the silk screen S against the silk screen S so that the silk screen S comes into contact with the base member 5, the carbon paper is removed.
The strike CP also moves in the same direction. At this time, the carbon paste CP is a printing pattern of the silk screen S.
Printed on the upper surface of the base member 5 through the
Antenna electrode portions 4A to 4F having a thickness of about 0 μm are formed. When the printing is completed, the screen printing device PR moves up and away from the stage ST. In connection with this operation, the rolls R1 and R2 rotate, and the long base member 5 is rotated.
Moves by one pitch and stops. Then, the screen printing device PR descends again to the stage ST, and the same operation as described above is repeated. The printed base member 5 is heated in the heating furnace H and subjected to a hardening process, whereby the antenna electrode portions 4A to 4F are given conductivity. Then, the base member 5 after the heat treatment is taken up by a take-up roll R2. The base member 5 wound around the roll R2 is cut into an appropriate size when necessary.

According to this embodiment, the antenna electrode portion 4A
4F to 4F are automatically formed on the base member 5 by screen printing using carbon paste CP. Positioning and adjustment of the distance between the antenna electrode portions can be omitted completely. Therefore, not only can productivity be significantly increased, but also manufacturing costs can be reduced. Moreover, if applied to the control unit shown in FIG.
The cost of the control unit can be reduced.

FIG. 4 shows a second example of the antenna electrode according to the present invention.
In this embodiment, the basic configuration is the same as that of the embodiment shown in FIG. The different point is that the antenna electrode 4 is divided into a plurality of, for example, two first and second antenna electrodes, and the antenna electrode portions 4A to 4F are formed in a belt-like loop shape, and a terminal hole 4Aa , 4Ba, 4
.. Are formed, and the height (length in the vertical direction) of the antenna electrode portions 4A to 4B is set smaller than the height of the antenna electrode portions 4C to 4F.

The first antenna electrode 4 is formed by forming antenna electrode portions 4A to 4B on a base member 5a by screen printing, and the second antenna electrode 4 is formed on the base member 5b. The antenna electrodes 4C to 4F are formed by screen printing. In particular, since the heights of the antenna electrode portions 4A to 4B are set smaller than the heights of the antenna electrode portions 4C to 4F, the first antenna electrode 4 is configured to be smaller in size than the second antenna electrode 4. I have.

According to this embodiment, even when it is difficult to arrange the single antenna electrode 4 as shown in FIG. 2 due to the structural problem of the backrest 1b of the sheet 1, the antenna electrode is divided into a plurality of pieces. By doing so, they can be easily arranged.

Also, since the holes 4Aa-4Fa for fixing the terminals are formed in advance in the respective antenna electrode portions, the lead wires (6a-6f) can be easily led out. And the electrical connection with the control unit can be easily performed.

FIGS. 5 and 6 show a third embodiment of an occupant detection system according to the present invention. The first embodiment or the second embodiment is applied to the antenna electrode 4. In the figure, reference numeral 10A denotes a control unit arranged at or near the sheet frame 3 of the sheet 1, for example, a switching circuit 18 having a plurality of switching means 18a to 18f, and a plurality of interfaces. And a control circuit 20 and a power supply circuit 22. Switching of the switching means 18a to 18f in the switching circuit 18 is performed based on a signal from the control circuit 20, whereby a gate signal is selectively supplied to the interface circuits Aa to Af. Interface circuit Aa
To Af are connected to connectors (or terminals) 19a to 19f, respectively, and antenna electrodes 4A to 4F are connected to the connectors 19a to 19f, respectively.
The connection is made using a wire. The output system of the interface circuits Aa to Af is connected to the control circuit 20. The control circuit 20 includes an airbag device 30.
Is connected. Further, the power supply circuit 22 is configured to generate a single Vcc power supply by stepping down the battery power supply (12 V) to, for example, 5 V. The generated Vcc power supply is one of the circuit elements constituting the control unit 10A. V
cc power is supplied to all circuit elements that require it.

In the above-described control unit 10A, the plurality of interface circuits Aa to Af have the same configuration as shown in FIG. These interface circuits (Aa) include, for example, an electric field generating means 11A, an impedance conversion circuit (buffer circuit) 23 connected to a transmission system of a high frequency output of the electric field generating means 11A, and an impedance conversion circuit. An AC-DC conversion circuit 24 converts the output of the circuit 23 into a direct current.

In the above-described interface circuit (Aa), the electric field generating means 11A is connected to, for example, a resistor 1 with respect to a Vcc power supply (a constant DC voltage) from the power supply circuit 22.
1a and a switching means (for example, a field effect transistor) 11b are connected in series, and a gate thereof is supplied with a signal from the control circuit 20, and a drain from the transmission system and a connector (19a). Antenna electrode (4
A) is configured to output a square wave high frequency low voltage to A). This high-frequency output is determined by a gate signal controlled by PWM (Pulse Wide Modulation) output from the control circuit 20, and its frequency is, for example, 120K.
It is configured to generate a high frequency low voltage of about Hz. The duty ratio of the gate signal (ON duty)
Is set to, for example, about 10%, but can be changed to an appropriate duty ratio depending on circuit constants, frequencies, and the like.

In the interface circuit Aa,
The impedance conversion circuit 23 is constituted by, for example, an operational amplifier 23a whose amplification factor is set to 1. Therefore, the output side of the impedance conversion circuit 23 has a low impedance, and the current required for reading by the CPU of the control circuit can be taken out without affecting the input side. An AC-DC conversion circuit 24 is connected to the output side of the impedance conversion circuit 23, and is constituted by, for example, a smoothing circuit including a resistor 24a and a capacitor 24b. The AC-DC conversion circuit 24
Is connected to the control circuit 20.

Next, the operation of the occupant detection system will be described with reference to FIGS. First, the control circuit 20
Only the switching means 18a is closed by the switching operation of the switching circuit 18 based on the signal from the other, and the other switching means 18b to 18f are opened. For this,
Electric field generating means 11A in interface circuit Aa
The switching means 11b is provided with a gate signal as shown in FIG. When the gate signal is high (Hig)
In each case h), the switching means 11b is turned on each time, the drain of the switching means 11b is set to the ground level, and is not output to the transmission system. At this time, the antenna electrode portion 4A
Is charged through the switching means 11b. on the other hand,
When the gate signal goes low, the switching means 11b is turned off, and a high frequency low voltage (for example, 120K) of a substantially square wave as shown in FIG.
Hz, + 5V) is output. This high-frequency output is supplied to the antenna electrode unit 4A via the transmission system and the connector 19a, and a weak electric field is generated around the antenna electrode unit 4A. As a result, different levels of current flow depending on whether or not the occupant is seated on the seat 1, and whether or not the occupant is distinguished (adult or child).

For example, when the seat 1 is not occupied by an occupant, a low-level current flows based on the stray capacitance existing around the antenna electrode portion 4A. At this time, the rise of the high frequency and low voltage of the transmission system is shown in FIG.
As shown in (b), the resistance is slightly reduced based on the CR component of the capacitance component of the stray capacitance and the resistance 11a of the electric field generating means 11A. On the other hand, when an occupant is seated on the seat 1, a large capacitance component exists around the antenna electrode portion 4A as compared with the stray capacitance in the vacant state, and a high-level current flows. Will flow. It should be noted that the capacitance component of the occupant is larger in adults than in children, and the level of current flowing through the antenna electrode is also higher. At this time, as shown in FIG. 7C, the rise of the high-frequency low voltage of the transmission system is represented by an exponential function based on the capacitance component larger than the stray capacitance and the CR time constant by the resistance 11a of the electric field generating means 11A. And become dull greatly. In addition, since this rise is slow, since the capacitance component differs between adults and children,
Large for adults and small for children.

As described above, the transmission system including the electric field generating means 11A and the transmission system exhibiting various patterns based on the CR time constant in the antenna electrode system have a high frequency and low voltage (voltage waveform).
Is subjected to impedance conversion in an impedance conversion circuit (buffer circuit) 23 comprising an operational amplifier 23a set to a single amplification factor. That is, the input side is high impedance.
The dance and the output side (AC-DC conversion circuit 24 side) have low impedance, and the current required for reading of the control circuit 20 can be appropriately taken in as needed. The output (high-frequency low voltage) of the impedance conversion circuit 23 is A
It is input to the C-DC conversion circuit 24. In this circuit 24, an AC line voltage is supplied by a resistor 24a and a capacitor 24b.
And is converted to a direct current as shown in FIG. 7 (d). In the figure, the dotted line indicates the DC conversion level when the seat is vacant, and the solid line indicates the DC conversion level when the occupant is seated, and there is a discernible level difference between the two. Note that this DC conversion level depends on the magnitude of the capacitance component existing around the antenna electrode if the resistance value of the resistor 11a is set to be constant in the above-described CR time constant. For example, the capacitance is large like an adult. In the case where the capacitance is small like a child, it becomes large, and when the sheet 1 is vacant, the size becomes large. The DC output of the AC-DC conversion circuit 24 is taken into the control circuit 20, A / D converted, and stored in the memory. The switching means 18a of the switching circuit 18 are switched to the switching means 18b...
Each time the antenna electrode portion 4B is switched to
Signals related to .about.4F are output from the respective interface circuits and taken into the control circuit 20 one after another.

The control circuit 20 has, for example, a
Thresholds (threshold data) relating to the presence or absence of an occupant in the vehicle and identification of the occupant (classification of adult or child) are stored in a memory (storage means). Specifically, the threshold value regarding the presence or absence of the occupant is set as follows. For example, when an occupant is seated on the sheet, the difference in the area of the antenna electrode portions 4A to 4F and the like causes a difference in capacitance components existing around the antenna electrode portions, but the seat is vacant. In this case, the stray capacitance becomes considerably larger than the stray capacitance existing around the antenna electrode portion. As a result, the antenna electrode portions 4A to 4F
There is also a significant difference in the level of current flowing through the vehicle, and when the occupant is seated, not only does a higher level of current flow than when the occupant is vacant, but also in relation to the difference in CR time constant, The blunting of the rise in the voltage waveform of the line voltage (high-frequency low voltage) of the transmission system increases, and the DC level output from the AC-DC conversion circuit 24 also decreases. Therefore, when the occupant is seated, the DC level becomes low as shown by the solid line in FIG. 7D, and when the occupant is vacant, the DC level becomes high as shown by the dotted line in FIG. . Therefore, the DC level between the solid line and the dotted line is set as a threshold value regarding the presence or absence of the occupant. If the DC output data is smaller than this threshold value, it is determined that the occupant is seated, and if it is larger, it is determined that the occupant is not seated.

The threshold value for the identification of the occupant is set as follows. For example, when an adult or child occupant is seated on a sheet, a difference occurs in a capacitance component existing around the antenna electrode portion due to a difference in an area facing the antenna electrode portion. As a result,
The levels of the currents flowing through the antenna electrode portions 4A to 4F are different. In the case of an adult occupant, the current level is higher than that of a child occupant. The blunting of the rise in the voltage waveform of the system line voltage also increases, and the DC level output from the AC-DC conversion circuit 24 also decreases. Therefore, an intermediate DC output level between an adult and a child is set as a threshold value for identification. If the DC output data is smaller than this threshold value, it is determined to be an adult, and if it is larger, it is determined to be a child.

Therefore, the signal data relating to the occupant's seating state and the like taken into the control circuit 20 are stored in the control circuit 2 in advance.
This is compared with threshold data relating to the occupant's seating status and the like stored in 0. For example, the interface circuit A
The actual data from a to Af are compared with a threshold value regarding the presence or absence of seating. If the actual data is smaller than the threshold value, it is determined that the occupant is seated on the sheet. If it is large, it is determined that the driver is not seated. In comparison with a threshold value for discrimination of seating, if actual data is smaller than the threshold value, it is determined that an adult occupant is seated, and if it is larger, a child occupant is seated. It is determined that there is. Based on this determination result, the airbag device 30
Is set to either the deployable or non-deployable state by the transmission signal from the control circuit 20. Therefore, if the vehicle collides, the airbag device 30 is appropriately controlled according to the identification result of the occupant, so that undesired deployment of the airbag can be prevented.

According to this embodiment, in the interface circuits Aa to Af, the transmission system in which the high frequency low voltage is output from the electric field generating means 11A is subjected to the AC-DC conversion via the impedance conversion circuit 23. Since the circuit 24 is connected, a line voltage (voltage waveform) having a relationship between the electric field generating means 11A and the current flowing to the antenna electrode units 4A to 4F via the transmission system is taken in and converted to direct current. ,
Based on the converted data, it is possible to appropriately judge the seating status of the occupant on the sheet and the like.

Since an impedance conversion circuit 23 is connected between the transmission system and the AC-DC conversion circuit 24, the input side has a high impedance, and the output side has a low impedance. When the DC output of the AC-DC conversion circuit 24 is taken into the control circuit 20, even if the control circuit 20 takes out the current required for reading, it does not affect the transmission signal in the transmission system. Therefore,
Highly accurate occupant detection becomes possible.

The capacitance component existing around the antenna electrode is determined by whether an adult occupant is seated on the sheet,
Alternatively, since it differs depending on whether or not a child occupant is seated, by appropriately setting the CR time constant of this capacitance component and the resistor 11a connected to the transmission system including the electric field generating means 11A, the high frequency low frequency in the transmission line can be reduced. Dulling corresponding to each situation can be generated at the rise of the voltage. Therefore, the difference in waveform due to the slow rising is converted from AC to DC by the AC-DC conversion circuit, so that the identifiable signal data is obtained.
The occupant's seating status and the like can be accurately determined based on the signal data.

Further, the high-frequency low voltage applied to the antenna electrodes 4A to 4F arranged on the sheet is output from the electric field generating means 11A, but the output is simply a single voltage from the power supply circuit 22. In order to obtain the Vcc power by switching the switching means 11b with a gate signal of a desired frequency (for example, 120 KHz), the DC power is converted into a high-frequency AC and then shaped into a square wave. Compared with the circuit, the circuit configuration of the control unit as well as the electric field generating means 11A can be simplified, and the cost of the system can be effectively reduced.

FIGS. 8 and 9 show a fourth embodiment of the occupant detection system according to the present invention, which is basically the same as the embodiment shown in FIGS. The different points are that the antenna electrode 4 is disposed on the dash-board portion DB facing the sheet 1 and that the interface circuit Aa is constituted by one. Incidentally, the control unit 10B is arranged at the dashboard part DB or in the vicinity thereof.

In this embodiment, the antenna electrode 4 has a dash board portion D facing the passenger seat and the driver seat, respectively.
Although it is desirable to arrange at B, it is also possible to arrange at only the passenger seat side. The antenna electrode 4 is constructed by forming an antenna electrode portion 4A on a base member (5) made of an insulating member by screen printing, and fixing the base member to the dash board portion DB. It is attached.

According to this embodiment, the occupant P seated on the seat 1 is moved to the dash board DB as indicated by the dotted line in FIG.
When approaching the (antenna electrode section 4A), the level of the DC signal taken into the control circuit 20 from the interface circuit Aa decreases in association with the increase in the current flowing through the antenna electrode section 4A. By comparing this actual data with a threshold value related to the approach state stored in the control circuit 20 in advance, the occupant P can use the dashboard.
It is possible to accurately detect whether or not it is unnecessarily approaching the storage unit DB. Therefore, when the occupant P is unnecessarily approaching the dash board portion DB, by setting the airbag of the airbag device 30 so as not to be deployed, it is possible to prevent the airbag from being undesirably deployed. .

It should be noted that the present invention is not limited to the above-described embodiment at all, and for example, the location of the antenna electrode is not limited.
In addition to the seat and the dashboard portion, it can be arranged on a door or a seat portion close to the door, or can be arranged on both the seat and the dashboard portion. In the case where a plurality of antenna electrode portions are arranged, the number of the antenna electrode portions can be appropriately increased / decreased. It can be formed into a shape.
The antenna electrode may be formed by sequentially forming the antenna electrode portion on a long base member, or the antenna electrode portion may be individually formed on the base member cut into a desired size in advance. . Also, the antenna electrode portion can be formed by spraying, coating, vapor deposition, or plating, in addition to screen printing using a liquid conductive member. In particular,
The screen printing apparatus is not limited to the structure of the illustrated example.
The antenna electrode according to the present invention can also be applied to a prior art occupant detection system. Further, based on the judgment result of the control circuit, a seal is used instead of the airbag device.
It is also possible to control the mounting state of the belt, the warning light, and the like.

[0052]

As described above, according to the present invention, the antenna electrode is formed by directly attaching the antenna electrode portion to the base member and the conductive member, as in the prior art. In addition, manual alignment of the antenna electrode portion with respect to the base member and adjustment of the distance between the antenna electrode portions can be completely omitted. Therefore, not only can productivity be significantly increased, but also manufacturing costs can be reduced. Moreover, when applied to an occupant detection system, the cost of the control unit can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of a passenger compartment of an occupant detection system according to the present invention, wherein FIG. 1 (a) is a side view and FIG. 1 (b) is a front view of FIG. 1 (a). FIG.

2 is a specific configuration diagram of the antenna electrode shown in FIG. 1, wherein FIG. 2 (a) is a plan view and FIG. 2 (b) is a cross-sectional view of FIG. 1 (a).

3A and 3B are diagrams for explaining a method of manufacturing an antenna electrode according to the present invention, wherein FIG. 3A is a side sectional view schematically showing a manufacturing line, and FIG. 3B is a screen printing apparatus. FIG.

FIG. 4 is an essential part plan view showing a second embodiment of the antenna electrode according to the present invention.

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

FIG. 6 is a specific circuit diagram of the interface circuit shown in FIG.

7A and 7B are diagrams for explaining the operation of the control unit shown in FIG. 5, in which FIG. 7A shows a gate signal output from the control circuit, and FIG. FIG. 3C is a diagram showing a signal waveform of the transmission system in FIG. 2, FIG. 3C is a diagram showing a signal waveform of the transmission system when the user is seated, and FIG.

FIG. 8 is an essential part side view showing a fourth embodiment of the occupant detection system according to the present invention.

9 is a circuit block diagram of a control unit applied to the occupant detection system shown in FIG.

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

11A and 11B are diagrams showing the arrangement of antenna electrodes on a sheet according to the prior art, wherein FIG. 11A is a side view, and FIG. 11B is a plan view of FIG.

12 is a specific configuration diagram of the antenna electrode shown in FIG. 11, wherein FIG. 12 (a) is a plan view and FIG. 12 (b) is FIG.
FIG.

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

14 is a circuit block diagram of an airbag device in the occupant detection system shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet 1a seating portion 1b backrest portion 4 antenna electrode 4A to 4F antenna electrode portion 5, 5a, 5b base member 10, 10A, 10B control unit 11, 11A electric field generating means 15 current detection circuit 23 impedance conversion Circuit 24 AC-DC conversion circuit 20 Control circuit 22 Power supply circuit 30 Airbag device A, Aa to Af Interface circuit PR Screen printing device W Frame S Screen SG Squeegee H Heating furnace SS1, SS2 Safety sensor SQ1, SQ2 Squib SW1, SW2 Switching element CC Control circuit GS Electronic acceleration sensor

Claims (8)

[Claims] An antenna electrode is arranged on a sheet and / or its periphery, an electric field is generated around the antenna electrode, and information data relating to a current flowing through the antenna electrode is detected based on the electric field. An occupant detection system configured to judge the seating status of the occupant on the seat based on the information, wherein the antenna electrode includes a base member made of an insulating member and a conductive member provided directly on the base member. An occupant detection system, wherein the occupant detection system is formed by attaching an antenna electrode section to the occupant detection section. 2. An antenna electrode is arranged on a sheet and / or its periphery, an electric field is generated around the antenna electrode, and information data relating to a current flowing through the antenna electrode is detected based on the electric field. An occupant detection system configured to judge the seating state of the occupant on the seat based on the information and set the airbag of the airbag device to a predetermined operation mode based on the judgment result. An occupant detection system, wherein the antenna electrode is formed by directly applying a conductive member to a base member made of an insulating member to form an antenna electrode portion. 3. An electric field is generated around a sheet and / or an antenna electrode disposed around the sheet, and information related to a current flowing through the antenna electrode is detected based on the electric field. An antenna electrode applied to an occupant detection system configured to judge a seating state of an occupant on a sheet or the like, wherein the antenna electrode is formed by directly connecting a conductive member to a base member made of an insulating member. An antenna electrode characterized in that it is formed by forming an antenna electrode portion by attaching to an antenna. 4. An electric field is generated around a sheet and / or an antenna electrode disposed therearound, and information related to a current flowing through the antenna electrode is detected based on the electric field, and based on this information, An antenna electrode applied to an occupant detection system configured to determine a seating state of an occupant on a seat, and the like, wherein the antenna electrode includes at least a base member made of an insulating member, and a base member. An antenna electrode portion made of a conductive member directly attached to a desired portion of the antenna member, and a lead wire derived from the antenna electrode portion and having an electrical connection with the antenna electrode portion. An antenna electrode comprising: 5. The antenna device according to claim 1, wherein the antenna electrode portion is formed by a conductive member into an appropriate shape such as a band shape including a band shape, a spiral shape, a meandering shape, a comb tooth shape, and a radial shape. Item 5. The antenna electrode according to item 3 or 4. 6. The antenna electrode portion is formed by any one of screen printing, spraying, coating, vapor deposition, and plating of a conductive member, such as a band including a band shape, a spiral shape, a meandering shape, a comb shape, and a radial shape. The antenna electrode according to claim 3, wherein the antenna electrode is formed in an appropriate shape. 7. An antenna in which a hole is formed in a part of said base member, and a conductive member is directly applied to a desired portion of said base member including said hole to form an antenna electrode portion. 5. The antenna electrode according to claim 3, wherein a lead wire is electrically and mechanically connected to the electrode portion by a connection means using a hole. 8. The conductive member contains at least a conductive filler, a binder mainly composed of a resin, and a solvent, and is heat-treated after being formed on the base member to form an antenna electrode portion. The antenna electrode according to any one of claims 3 to 7, wherein: