JP5560030B2 - Occupant detection system - Google Patents

Description

  The present invention relates to an occupant detection system and an occupant detection method, and in particular, in a state where an airbag of an airbag device can be deployed or cannot be deployed depending on the seating situation of the occupant in a passenger seat of an automobile equipped with the airbag device. The present invention relates to an occupant detection system that can be set to a state.

  Airbag systems are widely used as safety devices for automobiles, but depending on the occupant's physique and the attitude taken by the occupant, there is a possibility that the occupant may be at risk by deploying the front airbag. For this reason, for example, the US Federal Vehicle Standard “FMVSS208” stipulates that the airbag system controls the deployment / non-deployment of the front airbag based on the weight of the passenger seated in the passenger seat. .

Sensing methods for detecting an occupant are roughly classified into a weight sensor that senses the weight of the occupant, a sensing method that uses a piezoelectric sensor, and a sensing method that uses a capacitive sensor that senses the physique of the passenger, that is, the surface area.
FIG. 6A is a diagram illustrating the principle of an occupant detection system using a sensing method using a capacitive sensor as a sensing method. In this method, a weak electric field (EF) is generated on the antenna electrode arranged on the sheet, and electric charges are generated on the surface of the electrode and the object to be measured. As a result, the electrode and the surface of the object to be measured are capacitively coupled, and the capacitance change that changes depending on the physique and the seating situation can be captured as a change in displacement current.

  As shown in FIG. 6A, when a high frequency low voltage from the sine wave oscillation circuit OSC is applied to the antenna electrode E1, a weak electric field (EF) is generated around the antenna electrode E1, so that the antenna electrode E1 A displacement current I flows on the side. Since the value of the displacement current I is determined by the capacitance value formed between the antenna electrode E1 and the ground, it takes a different value depending on the relative permittivity of the object OB present in the vicinity of the antenna electrode E1. Therefore, the current flowing to the antenna electrode E1 side changes depending on whether the object to be measured OB is on the sheet or not. By utilizing this phenomenon, the seating state of the passenger on the seat can be detected by the physical quantity (in this case, the displacement current) obtained by the sensor.

In addition, the above regulations stipulate that in the normal distribution showing the weight distribution of an adult woman shown in FIG. 6 (c), the front airbag is developed for adults equivalent to the 5th percentile adult woman (5% distribution of the smaller distribution). A method is described that maintains function and suppresses the deployment of a front airbag below a child equivalent to a 6-year-old child (6 years old).
In other words, it is desirable to obtain a lot of information from the physique of the seat occupant and take measures to distinguish them.

  Therefore, as shown in FIG. 6B, a plurality of antenna electrodes, for example, the antenna electrode E2 is installed on the seat surface portion of the seat, and the antenna electrode E3 and the antenna electrode E4 are installed on the back surface, so that It is possible to obtain more physical quantities of the object to be measured (occupant) and more accurately detect the seating state of the occupant on the sheet.

  In order to use the information obtained from these sensors as control information for actually deploying / undeploying the airbag, it is important to distinguish between passengers, and the airbag system uses a preset threshold value. And a physical circuit (current value or capacity measurement value), which is a measurement result by the weak electric field technique, is provided, and data is periodically acquired from the sensor to determine the occupant.

  However, when the data from the sensor is affected by a disturbance, for example, when the sheet on which the sensor is placed overflows with water, the physical quantity may fluctuate, so an erroneous determination may be made. . Also, even if the same person is sitting, if you change the way you sit, the physical quantity will change, so it may be determined that it is a child even though it was previously determined that it is an adult .

  FIG. 7 is a diagram schematically showing such a problem. The horizontal axis shows the time since the ignition (IG) was turned on and the electronic control unit (ECU) was operated. As an example 1, when an adult is sitting in the passenger seat, as an example 2, the passenger seat is young. It shows a case where a person restraint system (CRS) is installed. When the sensor data changes due to the influence of the occupant's sitting in the passenger seat at time t1 or due to the influence of the disturbance (environmental change such as the above-mentioned flooding, vehicle behavior, for example, vehicle speed change), the delay time At time t2 after the lapse, Example 1 indicates that an adult is erroneously determined as a child, and in Example 2, CRS is erroneously determined as an adult. As described above, although the passenger in the passenger seat does not actually change, an erroneous determination is made. Therefore, it is necessary to improve the stability and continuity in the determination.

  As a technique for improving the stability and continuity of such determination, there is an occupant detection system in Patent Document 1, for example. In this method, a plurality of measurement electrodes using weak electric field technology are arranged on a passenger seat to detect the presence or absence of a passenger, physique, and the like. In addition, when the electrode surface is submerged during detection, the electrode other than the electrode being measured (non-measurement electrode) is set to the ground level (GND level), and the resistance component between the measurement electrode and the non-measurement electrode is reduced. The amount of water is detected by measurement, and the determination is continued according to the amount of water, or a signal that cannot be determined is generated, and the airbag is set to a deployable state or an undeployable state.

US Patent 6,696,948

  However, in the disclosed technique, the amount of water on the sheet is estimated by measuring the resistance component between the measurement electrode and the non-measurement electrode. Therefore, if a large amount of water overflows, the location of the water disappears and the water spreads over the entire surface of the seat, and the degree of water exposure between the measurement electrode and the non-measurement electrode increases, and the seating status of the seat is determined. There was a problem that I could not. In general, the seat frame is often connected to the vehicle body ground (vehicle body GND). When there is a large amount of moisture between the measurement electrode and the seat frame, the seating situation over a long period of time. There was a problem that could not be determined.

  Therefore, an object of the occupant detection system of the present invention is to reduce erroneous determination in occupant detection and improve the stability and continuity of determination even when the seat is flooded.

  In order to solve the above-described problems, an occupant detection system according to the present invention includes a plurality of antenna electrodes arranged on a seating surface portion of a sheet, and an electric field generation for generating a weak electric field around each of the plurality of antenna electrodes. , A current detection unit for detecting a current flowing based on each electric field generated in the periphery by the plurality of antenna electrodes, and signal data relating to a current flowing through the antenna electrode taken from the current detection unit And the threshold value data relating to the seating situation of the occupant stored in advance and the flooding situation of the seat surface portion of the seat, thereby determining the seating situation and the flooding situation of the occupant A drain hole disposed in a hanging groove in which the skin of the sheet is suspended on the pad of the sheet, extending through the skin and the pad until reaching the back surface of the sheet, Characterized in that it obtain.

  The drain hole is formed with respect to the flat surface as compared with the hanging groove that exists in the vicinity of the antenna electrode having a long distance from the flat surface formed by the seat frame that is electrically connected to the vehicle body ground among the plurality of antenna electrodes. It is characterized in that a large number of the suspension grooves are arranged in the vicinity of the antenna electrode having a short distance.

  The drain hole is provided inside a seat frame that is electrically connected to the vehicle ground when the seat surface of the seat is viewed in plan.

  The occupant detection system of the present invention further includes an airbag device having a function of deploying an airbag based on a collision, and the control unit transmits data based on a determination result to the airbag device, The airbag of the airbag device is set in either a deployable state or an undeployable state.

  The occupant detection system of the present invention is characterized in that the antenna electrode is an antenna electrode formed by printing a conductive paint on an insulating film substrate.

  In the occupant detection system of the present invention, a drain hole is provided in the hanging groove of the seat skin and water is drained under the seat, so that erroneous determination in occupant detection is reduced, and determination stability and continuity Can provide an improved passenger detection system. Moreover, even if the seat is flooded, it is drained under the seat through the suspension hole, so that it is possible to provide an occupant detection system that enables occupant detection at an early stage.

1 is a conceptual diagram of an occupant detection system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a simplified circuit configuration of the occupant detection system illustrated in FIG. 1. It is a schematic diagram which shows the seat seat surface part in the passenger | crew detection system shown in FIG. It is A-A 'sectional drawing of FIG. 3, and B-B' sectional drawing. It is a schematic diagram which shows the modification of the seat seat surface part shown in FIG. It is a figure for demonstrating the basic principle in the passenger | crew detection apparatus in a prior art. It is a figure for demonstrating the problem in the passenger | crew detection apparatus in a prior art.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
The configuration of the occupant detection system of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a diagram illustrating a schematic configuration of an occupant detection system including a seat, and FIG. 2 is a diagram illustrating a simplified circuit configuration of the occupant detection system.

  In FIG. 1, the seat includes a metal frame 10 that is mounted on the vehicle floor, a seat surface portion 11 that is fixed on the frame 10 and forms a seating portion of the seat, and an obliquely upward rear side from the rear of the seat surface portion 11. And a back surface portion 12 which is disposed toward the back and forms a backrest. The occupant detection system includes a plurality of antenna electrodes 121 to 123 disposed on the seat surface portion, a plurality of antenna electrodes 124 to 125 disposed on the back surface portion, a connector wiring 19, and an occupant detection unit 20 (ECU).

Here, in the seat surface portion 11, the antenna electrodes 121 to 123 are arranged so as to be separated from each other and adjacent to each other. Further, in the back surface portion 12, the antenna electrodes 124 to 125 are spaced apart and arranged adjacent to each other. In addition, about arrangement | positioning of the antenna electrodes 121-123 in the seat surface part 11, it comprises the characteristic part of this invention, and it mentions later for details.
The connector wiring 19 is a plurality of wire harnesses and the like, and connects the antenna electrodes 121 to 123 disposed on the seat surface portion 11 and the antenna electrodes 124 to 125 disposed on the back surface portion 12 to the occupant detection unit 20. doing.
The occupant detection unit 20 is a circuit that detects the state of the occupant seated on the seat and the wet state of the seat based on the current value I of the current flowing through the connector wiring 19 provided corresponding to each antenna electrode. It is installed in the inside.

As shown in FIG. 2, the occupant detection unit 20 includes a sine wave oscillation circuit OSC, a current / voltage detection circuit 21, a SW switching circuit 22, and a determination circuit 23. In FIG. 2, the antenna electrodes constituting the occupant detection system are representatively shown in the case of occupant detection and wet detection using the antenna electrode 122, and other antenna electrodes (the antenna electrode 121 and the antenna electrode) are shown. 123) is also the same for occupant detection and water detection.
Further, although the antenna electrodes 124 to 125 arranged on the back surface portion 12 are omitted, the occupant detection system has a plurality of measurement electrodes (antenna electrodes 121 to 123 arranged on the seat surface portion 11 and arranged on the back surface portion 12. The antenna electrodes 124 to 125) are arranged to comprehensively detect the presence or absence of a passenger, the physique, and the like.

The sine wave oscillation circuit OSC is a circuit that generates a weak electric field around the antenna electrode 122, and is configured to generate a sine wave having a frequency of about 120 KHz and a voltage of about 5V, for example.
The current / voltage detection circuit 21 detects the voltage value V of the alternating voltage generated by the sine wave oscillation circuit OSC, and detects the current value I of the current that flows based on the electric field generated by the antenna electrode 122 and the like around the antenna electrode. The voltage value V and the current value I are output to the determination circuit 23.

  As shown in FIG. 2, the SW switching circuit 22 switches between the occupant detection mode and the wet detection mode by switching the connection destination (node A or node B) of the switch SW. When connected to the node A, the antenna electrode 121 and the antenna electrode 123 are in an open state (OPEN). The antenna electrode 122 to which an AC voltage is applied by the sine wave oscillation circuit OSC forms an electric field (electric field EF (SW A side)) with the seat frame 10. The seat frame 10 is grounded via a vehicle body (not shown). This state is referred to as A mode (occupant detection mode: second measurement mode) when the antenna electrode 122 is used.

On the other hand, when connected to the node B, the antenna electrode 121 and the antenna electrode 123 are grounded. The antenna electrode 122 to which an AC voltage is applied by the sine wave oscillation circuit OSC is connected between the adjacent antenna electrode 121 and the antenna electrode 123 with an electric field (electric field EF (SW
B side)). This state is referred to as B mode (water detection mode: first measurement mode). In this way, the SW switching circuit 22 switches between the occupant detection mode and the wet detection mode.

  The determination circuit 23 calculates an impedance Z (V / I) based on the voltage value V and the current value I input from the current / voltage detection circuit 21, and calculates the reciprocal of the calculated impedance Z to thereby determine the admittance Y. Is calculated. The calculated admittance Y is generally expressed as Y = Re + j × Im. Here, Re (Real Part) is conductance, and Im (Imaginary part) is susceptance. J is an imaginary unit.

  As shown in the determination circuit 23 of FIG. 2, the Re-Im characteristic of the admittance Y is represented by orthogonal plane coordinates with the conductance Re [unit 1 / Ω] as the horizontal axis and the susceptance Im [1 / Ω] as the vertical axis. . Here, the value of the conductance Re is related to the R component (resistance component), and the conductance Re decreases as the R component increases. The value of the susceptance Im is related to the C component (capacitance component), and the susceptance Im increases as the C component increases. The coordinates on the orthogonal plane coordinates (Re, Im) are determined by Re and Im of the admittance Y.

First, the conductance Re and the susceptance Im calculated in the passenger detection mode will be described.
When the sheet is in a dry state (not covered with water), in the Re-Im characteristic of the admittance Y shown in FIG. 2, for example, compared to when the seat is empty (indicated by a circle in the figure), When an adult is seated (indicated by □ in the figure), it can be seen that the susceptance Im increases. This is because the object to be measured OB (in this case, an adult) is interposed between the antenna electrode 122 and the seat frame 10, and the relative permittivity becomes larger and the current value I becomes larger than in the case of an empty seat. is there.

  On the other hand, when the seat is flooded, the Re-Im characteristic of admittance Y shown in FIG. 2 shows that when the seat is empty (indicated by ● in the figure), when an adult is seated on the seat (in ■ in the figure). In both cases, the susceptance Im and the conductance Re increase. This is because moisture is interposed between the antenna electrode 122 and the antenna electrode 121 or the antenna electrode 123, and the relative dielectric constant is increased and the current value I is increased as compared with the case of both adults and vacant seats.

The determination circuit 23 compares the calculated susceptance Im of the admittance Y with a threshold value set in advance and stored in the determination circuit 23 to determine the seating state of the seat. That is, the determination circuit 23 stores in advance threshold values (threshold data) relating to, for example, the seating status (identification of presence / absence, identification of adult or child) of a passenger seated on a sheet. (Remembered). Specifically, the threshold value th2 (second threshold value) used for comparison with the calculated susceptance Im shown in the Re-Im characteristic of the admittance Y shown in FIG. 2 is stored. Here, the threshold th2 is a threshold for distinguishing whether an adult is seated or vacant.
However, as described above, depending on the degree of wetness of the seat, as shown in FIG. 2, the susceptance Im exceeds the threshold value th2 due to an increase in the admittance Y, and what is originally determined to be an empty seat is an adult. May be erroneously determined.

  Therefore, as shown in FIG. 2, the determination circuit 23 compares the conductance Re of the admittance Y with a preset threshold value th1 (first threshold value) in the moisture detection mode, and conductance Re Is greater than the threshold th1 (indicated by ▲ in the figure), the sheet is determined to be wet, and when the conductance Re is less than the threshold th1 (indicated by ∆ in the figure), the sheet Is determined not to be wet.

Thus, the determination circuit 23 calculates the admittance Y in each of the two modes based on the voltage value V and the current value I input from the current / voltage detection circuit 21.
The determination circuit 23 determines whether or not the seat is wet in the flood detection mode, and determines the seating status of the seat in the passenger detection mode. More specifically, the conductance Re calculated in the moisture detection mode is compared with a preset threshold value th1 to determine the moisture condition of the sheet. If it is determined that the vehicle is not wet, the susceptance Im calculated in the occupant detection mode is compared with the threshold th2. If the susceptance Im is greater than or equal to the threshold th2, an adult is seated on the sheet. If the susceptance Im is less than the threshold value th2, it is determined that the sheet is vacant.

  Of the admittance Y calculated in the occupant detection mode, it is possible to detect water exposure to some extent using the conductance Re. It is difficult to detect. Therefore, in the embodiment of the present invention, water detection is performed between the antenna electrode 122 (measurement electrode), the antenna electrode 121, and the antenna electrode 123 (non-measurement electrode).

  Based on the determination result described above, the determination circuit 23 transmits a deployment OK signal that enables deployment of the airbag or a deployment NG signal that disables deployment of the airbag to the airbag device. For example, when it is determined that the seat is not wet and it is determined that an adult is seated, a deployment OK signal that enables deployment of the airbag is transmitted. If it is determined that the seat is not wet and if it is determined that the seat is empty, either a deployment OK signal that enables deployment of the airbag or a deployment NG signal that disables deployment of the airbag is transmitted. To do.

  On the other hand, when it is determined that the seat is flooded, the seating situation is unknown, and therefore, a deployment NG signal that disables deployment of the airbag is transmitted. In addition, when it determines with having been flooded, you may take the structure which notifies a passenger | crew that a warning signal is transmitted together to a warning device etc., and the deployment or non-deployment of an airbag apparatus cannot be judged by flooding.

  Here, the airbag device includes, for example, a driver side squib circuit composed of a series circuit of semiconductor switching elements such as a safing sensor, a squib, and a field effect transistor, as well as a safing sensor, squib, and semiconductor switching. Based on the squib circuit on the passenger seat side composed of the elements, the electronic acceleration sensor (collision detection sensor), and the output signal of the electronic acceleration sensor, the presence or absence of a collision is judged and the signal is supplied to the gate of the semiconductor switching element And a control circuit having the function of The control circuit of the airbag device receives the transmission signal (deployment OK signal or deployment NG signal) from the determination circuit 23, and when the deployment OK signal is input, a gate signal is supplied to the semiconductor switching element. Is set to On the other hand, when the developed NG signal is input, the gate signal is set not to be supplied to the semiconductor switching element.

  The above is the schematic configuration of the occupant detection system shown in FIG. Next, the configuration of the antenna electrode portion will be described with reference to FIGS. FIG. 3 is a schematic top view of the antenna electrode portion disposed on the seat seat surface portion 11, that is, a plan view of the seat seat surface portion 11 as viewed from above. 4A is a cross-sectional view taken along line A-A ′ of FIG. 3, and FIG. 4B is a cross-sectional view taken along line B-B ′ of FIG. 3.

  3 and 4, the seat seat surface portion 11 is formed by superposing a urethane cushion pad 31 on a metal seat frame 10 formed in a rectangular frame shape, and the cushion pad 31 is enclosed by a seat skin 32. ing. The seat skin 32 is formed by stitching a plurality of skin materials, and is suspended in the downward direction of the seat pad in each of the suspension grooves 33. For suspension, a suspension bag (not shown) is sewn to the stitched portion of the seat skin, and a suspension wire (not shown) is inserted into the suspension bag, and the cushion pad 31 is formed when the suspension wire and cushion pad 31 are formed. A suspension wire (not shown) embedded in 31 is fixed by a hog ring.

  As shown in FIG. 4, the antenna electrode 121, the antenna electrode 122, and the antenna electrode 123 are interposed between the seat skin 32 and the cushion pad 31. The antenna electrode 121, the antenna electrode 122, and the antenna electrode 123 are electrodes formed on an insulating film substrate, respectively.

  The insulating film substrate is made of a resin such as polyethylene terephthalate (PET), polyimide, or polyethylene naphthalate (PEN), and has a thickness of about several tens of μm to 150 μm. The antenna electrode 121, the antenna electrode 122, and the antenna electrode 123 are each made by etching a copper foil pasted on an insulating film base material, or conductive made of silver or the like on an insulating film base material. It is formed by a method such as printing a paste.

  It should be noted that all these electrodes may be arranged on a single film by printing or the like, and the single film may be interposed between the seat skin 32 and the cushion pad 31. The sheet of film needs to be provided with an opening at a predetermined position on the film so as to avoid the above-described hogging position in each of the hanging grooves 33.

  Further, as shown in FIG. 3, a plurality of drain holes 13 are provided in the hanging groove 33 on the seat seat surface portion 11. As shown in FIG. 4A, the drain hole 13 is formed in the suspending groove 33 through the seat skin 32 and the cushion pad 31 to the back surface of the seat. In addition, it is good also as a structure which inserts a pipe into the drain hole 13 and prevents the penetration | infiltration of a water | moisture content to the horizontal direction so that a water | moisture content may not penetrate | invade into the cushion pad 31 sideways from the side surface of the water drain hole 13. Moreover, the drain hole 13 is provided so that the said hog ring location may be avoided. In addition, when the film on which the antenna electrode is printed or the like is composed of a single film as described above, that is, when the film is straddling the hanging groove 33, the drain hole 13 is naturally avoided. Thus, it is necessary to provide an opening at a predetermined location on the film.

  Next, the arrangement configuration of the drain hole 13 and the antenna electrodes 121 to 123 will be described. As shown in FIGS. 3 and 4A, the seat seat surface portion 11 is generally closer to the seat frame 10 in the rear portion of the seat than in the front portion of the seat due to the structure of the seat. That is, as shown in FIG. 4A, since the seat frame 10 is placed horizontally with respect to the vehicle floor, in FIG. 3, the antenna electrode 123 and the antenna electrode arranged from the front part to the rear part of the seat surface part 11 are arranged. 122 and the antenna electrode 121 are in such a relationship that the lines drawn perpendicularly to the plane formed by the seat frame 10 in this order become shorter. That is, the distance between the antenna electrode 123, the antenna electrode 122, and the antenna electrode 121 with respect to the seat frame 10 becomes shorter in this order. As described above, the antenna electrodes 121 to 123 have height dependency, and when the seat is wet, the front portion of the seating surface portion 11 where the antenna electrode 123 is located is higher than the rear portion, and water in the seat It can be said that it is easy to flow on the surface and has little water penetration, making it difficult for water to remain. On the other hand, the rear part of the seating surface part 11 where the antenna electrode 121 is located is lower than the front part and becomes a place where water permeates in the seat a lot and can be said to be a place where water remains easily.

  Therefore, when the seat surface portion 11 gets wet, the moisture flows on the seat surface from the front portion toward the rear portion.Therefore, there is a possibility that the seating situation of the occupant is erroneously detected at the time of determination by the antenna electrode 121 located at the rear portion. This is higher than the determination by the antenna electrode 123 located at the front. Moreover, if water remains in the rear part forever, erroneous determination in occupant detection will continue for a long time.

  Therefore, as shown in FIG. 3, the drain hole 13 is an antenna electrode (antenna at the front part of the seat) having a long distance from the seat frame 10 that is conducted to the vehicle body ground among the plurality of antenna electrodes (antenna electrodes 121 to 123). A small amount is arranged in the hanging groove 33 in the vicinity of the electrode 123). On the other hand, among the plurality of antenna electrodes, many are arranged in the hanging grooves 33 in the vicinity of the antenna electrode (antenna electrode 121 at the rear portion of the seat) whose distance from the seat frame conducted to the vehicle ground is short.

  Thus, by arranging the drain hole 13, the occupant detection system of the present invention provides the drain hole in the hanging groove of the seat skin and drains water under the seat. It is possible to provide an occupant detection system that can reduce erroneous determinations and improve the determination stability and continuity. Moreover, even if the seat is flooded, it is drained under the seat through the suspension hole, so that it is possible to provide an occupant detection system that enables occupant detection at an early stage.

FIG. 5 is a schematic view showing a modification of the seat seating surface portion 11 shown in FIG. 5, the antenna electrodes 121 to 123 arranged on the seating surface portion 11a have the same configuration as the antenna electrodes in FIG. 3 and are therefore given the same reference numerals. In FIG. 3 is provided more inside the seat frame 10 than in FIG.
As described above, the occupant detection system of the present invention calculates the susceptance Im of the admittance Y from the current value I based on the electric field generated between each antenna electrode and the seat frame 10 in the occupant detection mode, Therefore, when the drain hole 13a is disposed in the hanging groove 33 in the vicinity of the seat frame 10, the seat frame 10 gets wet when water is discharged, so that the resistance component, that is, the admittance. The conductance Re of Y increases and, as described above, the admittance Y also increases regardless of whether a vacant seat or an adult is seated. As a result, the margin for determination using the threshold value th2 is reduced, and erroneous determination is likely to occur.
Therefore, by arranging the drain hole 13a in the hanging groove 33 at a predetermined distance from the seat frame 10, it is possible to prevent erroneous detection due to moisture in the occupant detection mode.

  With this configuration, the occupant detection system according to the present invention can easily detect an occupant by reducing a change in admittance Y due to a resistance component due to moisture (conductance Re of admittance Y) in occupant determination. It is possible to provide an occupant detection system with fewer erroneous determinations and improved determination stability and continuity.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes modifications and the like without departing from the gist of the present invention. For example, the number of antenna electrodes arranged on the sheet can be appropriately increased or decreased, and the shape thereof can be formed in a rectangular shape, a belt shape, or the like in addition to a rectangular shape.

  In addition to the comparison between the threshold value stored in the determination circuit 23 in advance and the signal data relating to the current flowing through the actual antenna electrode, the occupant determination includes various seating patterns on the occupant's seat. The data regarding the passenger, the seating posture, and the like are stored in advance, and by comparison with the data, it is possible to determine whether the passenger is seated or not and whether the passenger is an adult.

  In the description of the above embodiment, the example in which the adult and the vacant seat are discriminated using the threshold value th2 has been described. However, the present invention is not limited to this example, and the threshold for comparison with the susceptance Im is described. There may be multiple values. For example, when an adult occupant or a child occupant is seated on a sheet, the level of the current flowing through each antenna electrode differs depending on the area facing each antenna electrode, and is input to the determination circuit 23. The level of signal data varies. In the case of an adult occupant, since the current value I is larger than that of a child occupant, the susceptance Im also increases.

  Therefore, a level slightly lower than the susceptance Im in the case of a child is the threshold th2a regarding whether or not a passenger is seated, and a level slightly higher than the susceptance Im in the case of a child is a threshold th2b that distinguishes between a child and an adult. , Respectively. That is, when the susceptance Im calculated in the passenger detection mode is smaller than the threshold value th2a, it is determined that the seat is empty. If the threshold value is greater than the threshold value th2a and smaller than the threshold value th2b, it is determined that a child is seated. If the threshold value is greater than or equal to the threshold value th2b, it is determined that an adult is seated.

  DESCRIPTION OF SYMBOLS 10 ... Frame, 11, 11a ... Seat surface part, 12 ... Back part, 13, 13a ... Drain hole, 121, 122, 123, 124, E1, E2, E3, E4 ... Antenna electrode, 19 ... Connector wiring, 20 ... Occupant detection unit, 21 ... current / voltage detection circuit, 22 ... SW switching circuit, 23 ... determination circuit, OSC ... sine wave oscillation circuit, th1, th2, th2a, th2b ... threshold, 31 ... cushion pad, 32 ... seat Skin, 33 ... Suspension groove, Im ... Susceptance, Re ... Conductance

Claims (3)

A plurality of antenna electrodes arranged on the seating surface of the sheet;
An electric field generator for generating a weak electric field around each of the plurality of antenna electrodes;
A current detector for detecting a current flowing based on each electric field generated around the antenna electrodes;
Signal data related to the current flowing through the antenna electrode taken in from the current detection unit, and threshold data related to the seating situation of the occupant and the wet condition of the seat surface portion of the seat stored in advance And a control unit that determines the seating situation and the flooding situation of the occupant by comparing
A drain hole arranged in a hanging groove in which the skin of the sheet is suspended to the pad of the sheet, extending through the skin and the pad until reaching the back surface of the sheet,
Equipped with a,
The drain hole is formed with respect to the flat surface as compared with the hanging groove that exists in the vicinity of the antenna electrode having a long distance from the flat surface formed by the seat frame that is electrically connected to the vehicle body ground among the plurality of antenna electrodes. Many are arranged in the hanging groove existing near the antenna electrode with a short distance,
The drain hole is a sheet that conducts to the vehicle ground when the seat surface of the sheet is viewed in plan.
An occupant detection system provided inside the frame . An airbag device having a function of deploying an airbag based on a collision;
The control unit transmits data based on a determination result to the airbag device, and sets the airbag of the airbag device in either a deployable state or an undeployable state. The occupant detection system according to claim 1 . The antenna electrode, the occupant detection system according to claim 1 or claim 2, characterized in that an antenna electrode formed by printing a conductive paint on an insulating film substrate.

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