JP5560029B2 - 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 above-disclosed technology, by measuring the resistance component between the measurement electrode and the non-measurement electrode, the amount of water on the sheet is to be estimated. There is a problem in that it is often limited between the measurement electrode and the non-measurement electrode, and in many cases it cannot be detected that water has been applied. In general, the seat frame is often connected to the vehicle body ground (vehicle body GND). If moisture exists between the measurement electrode and the seat frame, if the moisture penetrates to the vicinity of the seat frame, It can be detected that the water is covered by a change in electric field between the measurement electrode and the vehicle body GND. However, it is difficult to detect a resistance component when the amount of penetration is so small that moisture does not reach the seat frame. This indicates that there is a direction in which water flows easily due to the difference in height of the sheet surface, so in areas where moisture does not remain, the amount of water penetrating into the sheet decreases and it is difficult to detect water exposure by the measurement electrode. Yes.

  Therefore, in the occupant detection system of the present invention, in the occupant determination, (1) in a seat, water easily flows on the surface of the seat, and in a place where water permeates into the seat less (a place where moisture hardly remains), resistance due to moisture Increase the component change, or (2) make it easier to detect water exposure by increasing the resistance component change due to moisture in a place where water permeates the sheet (where water tends to remain). Therefore, it is an object to reduce erroneous determination in occupant detection and to improve the stability and continuity of determination.

  In order to solve the above problems, an occupant detection system according to the present invention includes a seat surface portion or a back surface portion of a sheet, or a plurality of antenna electrodes arranged on both the seat surface portion and the back surface portion, and the plurality of antennas. In order to generate a weak electric field in each of the periphery of the plurality of antenna electrodes, and the wet detection electrodes disposed on the seat surface portion or the back surface portion, or both the seat surface portion and the back surface portion. Electric field generator, a current detector that detects a current flowing based on each electric field generated by the plurality of antenna electrodes in the periphery, and in the first measurement mode, the signal data is stored in advance. Is compared with the first threshold data related to the wet state, and in the second measurement mode, the antenna electrode taken in from the current detection unit is determined. Flowing electricity A control unit for determining the seating status of the occupant by comparing the signal data related to the occupant and the second threshold data related to the seating status of the occupant stored in advance. The water-detecting electrode is characterized in that the water in the sheet is easy to flow on the surface and is long in the opposite direction to the plurality of antenna electrodes in a place where water penetration is small.

  The wet detection electrode is adjacent to the antenna electrode having a long distance from the plane formed by the seat frame that is electrically connected to the vehicle body ground among the plurality of antenna electrodes, and the opposing length to the antenna electrode is long. It is characterized by being.

  In order to solve the above problems, an occupant detection system according to the present invention includes a seat surface portion or a back surface portion of a sheet, or a plurality of antenna electrodes arranged on both the seat surface portion and the back surface portion, and the plurality of antenna electrodes. A weak electric field is generated in each of the periphery of the plurality of antenna electrodes and the wetted detection electrodes disposed on the seating surface portion or the back surface portion or both the seating surface portion and the back surface portion so as to face the electrodes of the antenna. An electric field generating unit for detecting the current, a current detecting unit for detecting a current flowing based on each electric field generated in the periphery by the plurality of antenna electrodes, and in the first measurement mode, storing the signal data in advance. The first threshold data related to the water exposure situation that is being used is compared to determine the water exposure situation, and in the second measurement mode, the antenna captured from the current detection unit Flow to electrode A control unit for determining the seating status of the occupant by comparing the signal data related to the current to the current and the second threshold data related to the seating status of the occupant stored in advance. The electrode for water detection is characterized in that the opposed length of the plurality of antenna electrodes is long at a location where water permeates the sheet.

  The wet detection electrode is adjacent to an antenna electrode located near a hanging portion in which the skin of the sheet is suspended from the pad of the sheet, and is opposed to the antenna electrode. Is arranged long.

  In the first measurement mode, the control unit generates an electric field between the antenna electrode and the wet detection electrode, and is based on an impedance between the antenna electrode and the wet detection electrode. The wet condition is determined by using the resistance component of admittance as signal data, and in the second measurement mode, an electric field is generated between the antenna electrode and a seat frame connected to the ground of the vehicle body, and the antenna electrode and the vehicle body are generated. The seating state of the occupant is determined using the admittance capacitance component based on the impedance to the ground as signal data.

  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 according to the present invention, in the occupant determination, (1) in a seat, water easily flows on the surface of the seat, and in a place where water permeates into the seat less (a place where moisture hardly remains), Increase the change, or (2) Increase the resistance component change due to moisture in a place where water permeates a lot of the seat (where moisture tends to remain). It is possible to provide an occupant detection system in which erroneous determination in detection is reduced and stability and continuity of determination are improved.

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 wet detection electrode 13, 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 12, 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 and the to-be-water-detected electrode 13 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 each of the antenna electrodes 121 to 123 disposed on the seat surface portion 11, each of the antenna electrodes 124 to 125 disposed on the back surface portion 12, and the occupant detection unit 20 Is connected.
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 each connector wiring 19 provided corresponding to each antenna electrode. Installed inside the seat.

  As shown in FIG. 2, the occupant detection unit 20 includes a sine wave oscillation circuit OSC, a current and voltage detection circuit 21, a SW switching circuit 22, and a determination circuit 23. In FIG. 2, the antenna electrode 122 is representatively shown for the antenna electrodes constituting the occupant detection system, and the other antenna electrodes are omitted, but the occupant detection system includes a plurality of measurement electrodes ( 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 are disposed 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 and voltage detection circuit 21 detects the voltage value V of the AC 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 around the antenna electrode. The circuit outputs a voltage value V and a current value I 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 water detection electrode 13 is 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).

  On the other hand, when connected to the node B, the water detection electrode 13 is grounded. The antenna electrode 122 to which an alternating voltage is applied by the sine wave oscillation circuit OSC forms an electric field (electric field EF (SW B side)) between the adjacent wet detection electrodes 13. 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 and voltage detection circuit 21, and calculates the reciprocal number 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 intervenes between the antenna electrode 122 and the wet detection electrode 13, and the relative dielectric constant increases and the current value I increases compared to the case of both adults and empty 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.

As described above, 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 and 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 conductance Re. It is difficult to detect. Therefore, in the embodiment of the present invention, a water detection electrode is provided, and water detection is performed between the antenna electrode and the water detection 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 wet detection electrode 13, 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 wet detection electrode 13, 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 wet detection electrode 13, the antenna electrode 121, the antenna electrode 122, and the antenna electrode 123 each etch a copper foil attached on an insulating film substrate, or on an insulating film substrate. It is formed by a method such as printing a conductive paste made of silver or the like.

  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 have an opening at a location corresponding to the above-described hog ring location in each of the hanging grooves 33.

  Next, the arrangement configuration of the wet detection electrode 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 is wet, the moisture flows from the front portion toward the rear portion on the seat surface, so that the periphery of the antenna electrode 123 located at the front portion is a place where the penetration of water into the seat is small. On the other hand, the periphery of the antenna electrode 121 located at the rear portion is a place where water permeates more into the sheet than the periphery of the antenna electrode 123. As described above, since the degree of moisture is different in the seat, the determination result when the admittance Y is calculated in the above-described moisture detection mode and the occupant's seating situation and the flooding situation are detected is determined for each antenna electrode. Will be different.

  For example, it is assumed that an adult is seated and the front part of the seat is flooded in a state where the front part of the seat part 11 is approached. When the determination circuit 23 determines based on the current I flowing through the antenna electrode 123 at the front, the water may flow to the rear and may be determined not to be wet depending on the degree of water. The determination circuit 23 comprehensively determines the seating status based on the determination results for all the antenna electrodes and outputs an airbag deployment / non-deployment signal. If there is a difference in the determination result when it is done, it will be difficult to detect water exposure and it will be easy to make an erroneous determination. That is, although any part of the seat is wet, it is erroneously determined that it is not wet in the water detection mode shown in FIG. Occupant detection may be performed in a region where the determination result of the capacitance component is close to the threshold value th2, and erroneous determination is likely to occur.

  Therefore, as shown in FIG. 3, the wet detection electrode 13 is an antenna electrode (seat front portion) having a long distance from the seat frame 10 that is electrically connected to the vehicle body ground among the plurality of antenna electrodes (antenna electrodes 121 to 123). The antenna electrode 123) is adjacent to the antenna electrode 123, and the length facing the antenna electrode 123 is long. On the other hand, among the plurality of antenna electrodes, an antenna electrode (antenna electrode 121 at the rear of the seat) having a short distance from the seat frame that is conducted to the vehicle ground is not adjacent to the water detection electrode 13. In FIG. 3, the antenna electrode 123 and the wet detection electrode 13 are not adjacent to each other, but the opposing length may be shortened from the front of the seat to the rear of the seat.

  With such a configuration, the occupant detection system of the present invention is (1) resistance to moisture in a place where water easily flows on the surface of the seat and where water penetration into the seat is low (a place where moisture hardly remains). By increasing the change in the component (conductance Re of admittance Y), it is easy to detect water exposure, so there are fewer occupant detection mistakes, and the occupant detection system with improved determination stability and continuity. Can be provided.

FIG. 5 is a schematic view showing a modification of the seat seating surface portion 11 shown in FIG. In FIG. 5, the antenna electrodes 121 to 123 arranged on the seating surface portion 11 a have the same configuration as the antenna electrodes in FIG. 3, and therefore have the same reference numerals, while the water detection electrode 13 a is an antenna. As a configuration in which the opposing length of each antenna electrode is long between the electrode 123 and the hanging groove 33 located in the front part of the seat and between the antenna electrode 122 and the hanging groove 33 located in the rear part. Yes. The wet detection electrode 13 a may be provided inside the hanging groove 33.

  When the seat surface portion 11a gets wet, the moisture flows from the front to the rear on the seat surface and tends to be sucked into the seat in the vicinity of the suspending groove 33. It is a place where people can easily gather. Further, even in the process of drying the wet sheet, the vicinity of the hanging groove 33 tends to dry with a delay.

  Therefore, the resistance between the antenna electrode and the wet detection electrode is recovered until the wet detection electrode 13a is recovered from the wet condition by setting the facing length of the wet detection electrode 13a in the vicinity of the hanging groove 33 to be long. The component (conductance Re of admittance Y) is kept low. That is, it is possible to prevent erroneous detection due to moisture by setting the length facing the antenna electrode to be long and determining that it is in a wet condition until the determination circuit 23 determines that it is less than the threshold value th1.

  With such a configuration, the occupant detection system of the present invention (2) changes the resistance component (conductance Re of admittance Y) due to moisture in a place where water permeates the seat (a place where moisture tends to remain). Increasing the size makes it easier to detect water exposure, so that it is possible to provide an occupant detection system in which erroneous determination in occupant detection is reduced and the stability and continuity of determination are improved.

  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.

  Further, in the description of the present embodiment, the configuration in which the wet detection electrode is disposed on the seat surface portion 11 of the seat has been described. However, the wet detection electrode may be disposed on the seat back surface portion 12 as a matter of course. In such a case, a plurality of antenna electrodes (antenna electrodes 124 and 125 in FIG. 1) are arranged on the back surface of the seat, and the water detection electrode and the antenna electrode are opposed to each other in plan view (viewing the back of the seat from the front). The length may be shorter from the upper antenna electrode to the lower antenna electrode.

  DESCRIPTION OF SYMBOLS 10 ... Frame, 11, 11a ... Seat surface part, 12 ... Back part, 13, 13a ... Electrode for water detection, 121, 122, 123, 124, E1, E2, E3, E4 ... Antenna electrode, 19 ... Connector wiring, DESCRIPTION OF SYMBOLS 20 ... Passenger detection unit, 21 ... Current and voltage detection circuit, 22 ... SW switching circuit, 23 ... Judgment circuit, OSC ... Sine wave oscillation circuit, th1, th2, th2a, th2b ... Threshold value, 31 ... Cushion pad, 32 ... Seat skin, 33 ... Hanging groove, Im ... Susceptance, Re ... Conductance

Claims (5)

A plurality of antenna electrodes arranged on the seat surface portion or the back surface portion of the sheet, or both the seat surface portion and the back surface portion;
Opposed to the electrodes of the plurality of antennas, the seat surface portion or the back surface portion, or the wet detection electrode disposed on both the seat surface portion and the back surface portion,
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;
In the first measurement mode, the water condition is determined by comparing the signal data with the first threshold data related to the water condition stored in advance. In the measurement mode, signal data relating to the current flowing through the antenna electrode taken in from the current detection unit, and second threshold data relating to the seating situation of the occupant stored in advance are provided. And a control unit for determining the seating status of the occupant by comparing the
The wet detection electrode is formed of a seat frame that is electrically connected to the vehicle body ground, and has a length that is opposite to the antenna electrode that has a long distance from the plane formed by the seat frame that is electrically connected to the vehicle body ground. An occupant detection system, characterized in that the occupant detection system is arranged longer than the opposing length of the antenna electrode with a short distance from the plane . A plurality of antenna electrodes arranged on the seat surface portion or the back surface portion of the sheet, or both the seat surface portion and the back surface portion;
Opposed to the electrodes of the plurality of antennas, the seat surface portion or the back surface portion, or the wet detection electrode disposed on both the seat surface portion and the back surface portion,
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;
In the first measurement mode, the water condition is determined by comparing the signal data with the first threshold data related to the water condition stored in advance. In the measurement mode, signal data relating to the current flowing through the antenna electrode taken in from the current detection unit, and second threshold data relating to the seating situation of the occupant stored in advance are provided. And a control unit for determining the seating status of the occupant by comparing the
The wet detection electrode is opposed to the antenna electrode at a location adjacent to the antenna electrode located near the hanging portion where the skin of the sheet is suspended from the pad of the sheet among the plurality of antenna electrodes. An occupant detection system having a long length . In the first measurement mode, the control unit generates an electric field between the antenna electrode and the wet detection electrode, and is based on an impedance between the antenna electrode and the wet detection electrode. The wet condition is determined by using the resistance component of admittance as signal data, and in the second measurement mode, an electric field is generated between the antenna electrode and a seat frame connected to the ground of the vehicle body, and the antenna electrode and the vehicle body are generated. The occupant detection system according to any one of claims 1 and 2 , wherein a seating state of the occupant is determined by using, as signal data, a capacitance component of admittance based on an impedance to the ground. 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 any one of claims 1 to 3 . The occupant detection system according to any one of claims 1 to 4 , wherein the antenna electrode is an antenna electrode formed by printing a conductive paint on an insulating film base material.

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