JP5223542B2 - Occupant posture detection device and occupant posture detection method - Google Patents

Description

  The present invention relates to an occupant posture detection device and an occupant posture detection method for detecting the posture of an occupant seated in a vehicle seat.

  With the improvement in performance of vehicles such as automobiles, for example, the deployment of airbags for protecting passengers in the event of a collision is being controlled based on the posture of the passengers. As a device for detecting such an occupant's posture, for example, a head position detection system disclosed in Patent Document 1 below is known.

  In this head position detection system, an oscillation electrode that is electrically connected in high frequency with an occupant sitting on a seat (seat) is arranged in a seat seat (sitting portion), and an oscillation output is generated between the oscillation electrode and a metal frame. An oscillating unit to be applied and a distance measuring sensor in which a receiving electrode is insulated from the ceiling of the passenger compartment so as to face the oscillating electrode.

  In addition, the head position detection system includes a calibration sensor that measures a measurement receiving electrode that is separated from a conductor surface that is electrically connected to an occupant by a known distance and that is opposed to the conductor surface and insulates the calibration receiving electrode. And a processing circuit for determining each distance in the receiving electrode and a characteristic curve relating to the output voltage, and applying each output voltage value to the corresponding characteristic curve to obtain each distance. And it is supposed that the position of a head will be detected by measuring the distance between a passenger | crew's head and a receiving electrode.

JP 2002-365011 A

  However, in the head position detection system disclosed in Patent Document 1 described above, since the oscillation electrode and the reception electrode are respectively disposed above and below the seat, the wiring length becomes long and the system configuration becomes complicated. Therefore, there is a problem that it is difficult to reduce the cost.

  An object of the present invention is to provide an occupant posture detection device and an occupant posture detection method that can be configured at low cost and can detect the posture of an occupant with high accuracy in order to eliminate the above-described problems of the prior art. .

  In order to solve the above-described problems and achieve the object, an occupant posture detection device according to the present invention has at least three positions on a ceiling of a passenger compartment above a vehicle seat so that a position on a predetermined plane can be detected. A detection electrode that detects the electrostatic capacitance between the head of the human body seated on the seat and the passenger compartment ceiling, and is connected to the detection electrode, based on detection signals from the detection electrodes A detection circuit that detects a position of the head of the human body and a posture determination circuit that determines a sitting posture of the human body according to a detection result from the detection circuit.

  By configuring the occupant posture detection device according to the present invention as described above, it is only necessary to provide the detection electrode on the ceiling of the passenger compartment as compared with the conventional one, and the configuration such as the oscillation electrode and the reception electrode is not required. In addition to being able to be configured, there is no problem of the distance between these electrodes, so that it can be configured at low cost and can detect the posture of the occupant with high accuracy. As the human head, it is particularly preferable to detect the top of the head.

  The detection circuit is connected to, for example, the detection electrode via a changeover switch, and is further connected to the detection electrode via the changeover switch, and further includes a drive circuit that outputs a predetermined voltage to each detection electrode. The posture determination circuit includes, for example, the switching so that when one detection electrode of the detection electrodes is alternatively connected to the detection circuit, the other detection electrode is connected to the drive circuit. Controls the switching operation of the switch.

  Further, the detection circuit detects the position of the head of the human body directly from the capacitance value of each of the detection electrodes, and then corrects the correction value in the X direction of the position of the head and the Y of the position of the head. A direction correction value is obtained from the capacitance value of each detection electrode, and a correction calculation process required for further determining the sitting posture of the human body in the posture determination circuit based on the correction value is further performed. Also good.

  The posture determination circuit may be configured to output information regarding the determined sitting posture of the human body to an ECU including a function of controlling deployment of an airbag mounted on the vehicle.

  In addition, the detection electrode is arranged on the ceiling of the passenger compartment, for example, in a triangular plane shape with one apex on the front side of the vehicle, or in a triangular plane shape with one apex on the rear side of the vehicle. In the case where four more are arranged, for example, they may be arranged in a rectangular plane shape that forms sides in the front-rear direction and the left-right direction of the vehicle, for example.

  A shield part that is electrically insulated from the detection electrode may be further provided on the back side and / or the periphery of the detection electrode, and the shield part is provided with the same potential as the detection electrode, for example. It is good to be.

  Further, the detection circuit includes, for example, storage means for storing a capacitance value when a human body is not seated in the seat in advance, and the capacitance stored in the storage means when the human body is seated. The detection result may be output using the increment from the value as the detection value.

  For example, the detection circuit may include a CV conversion type capacitance detection circuit that converts capacitance detected by each detection electrode into a voltage.

  In addition, the detection circuit has, for example, a differential operation type capacitance detection circuit, and is connected to an input terminal of the capacitance detection circuit having a phase opposite to the detection electrode in the vicinity of each detection electrode. An electrode may be disposed.

  According to the occupant posture detection method of the present invention, the head of the human body seated on the seat is provided by at least three detection electrodes provided on the ceiling of the passenger compartment above the seat of the vehicle so that the position on the plane can be detected. And detecting the position of the head of the human body based on the detection signal from each detection electrode indicating the detected capacitance. The seating posture of the human body is determined with reference to the position of the head.

  ADVANTAGE OF THE INVENTION According to this invention, the passenger | crew attitude | position detection apparatus and passenger | crew attitude | position detection method which can be comprised cheaply and can detect a passenger | crew's attitude | position with high precision can be provided.

  Hereinafter, preferred embodiments of an occupant posture detection device and an occupant posture detection method according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an explanatory diagram illustrating an example of the overall configuration of an occupant posture detection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram illustrating an example of detection electrodes of the occupant posture detection device, and FIG. FIG. 4 is an explanatory diagram for explaining an example of the operation principle of the detection device, FIG. 4 is an explanatory diagram for explaining a determination operation in the left-right direction of the passenger posture detection device, and FIG. 5 is a front-rear direction determination of the passenger posture detection device. It is explanatory drawing for demonstrating operation | movement.

  FIG. 6 is a block diagram showing an example of a capacitance detection circuit of the occupant posture detection device according to one embodiment of the present invention, and FIG. 7 is an operation showing an example of operation waveforms of the circuit unit of the occupant posture detection device. It is a waveform diagram.

  As shown in FIG. 1, the occupant posture detection device 100 according to the present embodiment is, for example, in the passenger compartment ceiling 2 above the seat 40 of the vehicle 1, for example, the head of an occupant (human body) 48 sitting on the seat 40. A capacitance sensor unit 10 having three detection electrodes (a first detection electrode 11, a second detection electrode 12, and a third detection electrode 13) arranged so as to detect a planar position of the unit 49; The circuit unit 20 is configured to determine the sitting posture based on the position of the head 49 of the occupant 48 seated on the seat 40 using the output from the capacitance sensor unit 10.

  In each of the detection electrodes 11 to 13 of the capacitance sensor unit 10, for example, the first detection electrode 11 is a vertex on the front side of the vehicle 1, and the second and third detection electrodes 12 and 13 are on the left and right sides of the vehicle 1 on the seat 40. The vehicle interior ceiling part 2 is arranged so as to be spaced apart in the direction and to form a triangular plane (for example, an isosceles triangle having the first detection electrode 11 as a vertex on the front side) when the detection electrodes 11 to 13 are linearly connected. It is arrange | positioned in the inside of a vehicle or the vehicle interior side surface. And the electrostatic capacitance sensor part 10 detects the electrostatic capacitance between the head 49 of the passenger | crew 48 and the vehicle interior ceiling part 2 (specifically detection electrodes 11-13). More specifically, the capacitance sensor unit 10 detects the capacitance between the top of the head 49 of the occupant 48 and the detection electrodes 11 to 13.

  In addition, in order to promote modularization of components, the capacitance sensor unit 10 includes the first to third detection electrodes 11 to 13 formed on one surface side of a substrate (not shown) as described above. The circuit unit 20 may be disposed on the same surface or the other surface side of the substrate. Of course, each part may be arrange | positioned separately depending on the aspect of arrangement | positioning.

  When the capacitance sensor unit 10 or the like is formed on a substrate, for example, a flexible printed board, a rigid board, a rigid flexible board, or the like is used as the board. Each of the detection electrodes 11 to 13 is an insulator such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyamide (PA), or epoxy resin when the substrate is made of a flexible printed board. It consists of metal materials, such as copper, copper alloy, or aluminum, which are patterned on a base material made of In addition, each detection electrode 11-13 may be formed in a membrane circuit, or may be made of a conductive adhesive material or other conductive metal.

  Each of the detection electrodes 11 to 13 is connected to the electrostatic capacitance detection circuit 21 of the circuit unit 20 through, for example, changeover switches SW1, SW2, and SW3, and shield drive is performed through these changeover switches SW1 to SW3. The circuit 23 is connected. Although illustration is omitted, the shield drive circuit 23 may be provided in the circuit unit 20.

  On the other hand, the circuit unit 20 includes, for example, a capacitance detection circuit 21 that detects each capacitance value based on a detection signal indicating the capacitance detected by the detection electrodes 11 to 13, and the capacitance detection. An A / D converter 22 that converts an analog signal from the circuit 21 into a digital signal, and various operation controls and arithmetic processing of the occupant posture detection device 100 based on the information converted into a digital signal by the A / D converter 22 And a CPU 29 that determines the seating posture of the occupant 48 and outputs information on the determined seating posture (posture information) to, for example, an ECU (electronic control unit) mounted on the vehicle 1. Has been.

  The ECU has, for example, a function of controlling the deployment of an airbag mounted on the vehicle 1 (that is, controlling the opening direction of the airbag, the inflation rate, etc.), and also includes attitude information from the occupant attitude detection device 100 of this example. Referring to, it is configured to be able to control the deployment of the airbag.

  Each of the change-over switches SW1 to SW3 is composed of a unit such as a multiplexer, an analog switch, an FET, or a relay, for example, and the CPU 29 of the circuit unit 20 controls the changeover operation of each of the change-over switches SW1 to SW3 by outputting a switch control signal. To do. Specifically, in the occupant posture detection device 100 of this example, the following switching control is performed.

  That is, when the switching control signal from the CPU 29 switches, for example, SW1 so that the first detection electrode 11 and the capacitance detection circuit 21 are connected, SW2 and SW3 are the second detection electrode 12 and the third detection signal. Switching is performed so that the electrode 13 is connected to the shield drive circuit 23.

  For example, when SW2 is switched so that the second detection electrode 12 and the capacitance detection circuit 21 are connected, SW1 and SW3 are the first detection electrode 11 and the third detection electrode 13 are the shield drive circuit 23. It is switched to be connected.

  Further, for example, when the switch SW3 is switched so that the third detection electrode 13 and the capacitance detection circuit 21 are connected, the first detection electrode 11 and the second detection electrode 12 are connected to the shield drive circuit 23 for SW1 and SW2. It is switched to be connected. As described above, the CPU 29 detects the detected capacitance when each of the detection electrodes 11 to 13 and the capacitance detection circuit 21 are alternatively connected (when switched in order). Based on the value, the sitting posture of the occupant 48 is determined.

  The shield drive circuit 23 is configured to give a potential equivalent to the potential given by the capacitance detection circuit 21 to the connected detection electrode. Thereby, it is possible to prevent electrostatic capacitance coupling between the detection electrodes 11 to 13 and to detect the electrostatic capacitance with high accuracy for each of the detection electrodes 11 to 13.

  Further, the shield drive circuit 23 may give a potential generated through an amplifier (buffer) having a single input impedance higher than the potential given to each of the detection electrodes 11 to 13, for example. When the detection circuit 21 is of a differential operation type, an equivalent potential may be applied by connecting a non-inverting input portion of an operational amplifier.

  As shown in FIG. 2, each of the detection electrodes 11 to 13 is formed in a rectangular shape, for example, and is electrically insulated from each of the detection electrodes 11 to 13 on the back surface side (the side opposite to the detection range side). The shield part 18 for suppressing the detection on the back surface side and the shield part 19 that provides the same effect around each of the detection electrodes 11 to 13 may be used. These shield portions 18 and 19 are given the same potential as, for example, the respective detection electrodes 11 to 13, and if these are provided, the vehicle compartment ceiling 2 and the head 49 (specifically, the top of the head) are more accurate. Can be detected.

  The occupant posture detection device 100 uses a principle that the occupant 48 has a very large volume and dielectric constant compared to the detection electrodes 11 to 13 and can be regarded as a ground (GND). And the structure which can determine the seating attitude | position of the passenger | crew 48 is employ | adopted for the circuit part 20 using the electrostatic capacitance between each detection electrode 11-13 and a ground (for example, passenger | crew 48).

  Therefore, according to the occupant posture detection device 100 having such a configuration, compared with a detection method that requires transmission and reception of signals, such as the head position detection system described in the section of the related art, A highly accurate system can be constructed with a simple configuration. Therefore, the occupant posture detection device 100 according to the present embodiment can be configured at low cost.

  The occupant posture detection device 100 operates as shown in FIG. 3, for example. Note that (1), (2), and (3) in the graph in FIG. 3 correspond to the first to third detection electrodes 11 to 13, respectively. As shown in FIG. 3A, for example, when the occupant 48 is seated near the front right side of the vehicle 1 with respect to the seat 40, the detection value ΔC of (1) of the first detection electrode 11 is the second value. Since the detection value ΔC of (2) of the detection electrode 12 and the detection value ΔC of (3) of the third detection electrode 13 are larger, the position of the head 49 (for example, the top of the head, the same applies hereinafter) of the occupant 48 is first. It can be seen that it is in the vicinity of the lower side of the detection electrode 11 (that is, in front of the seat 40).

  Further, when the detection value ΔC of (2) of the second detection electrode 12 and the detection value ΔC of (3) of the third detection electrode 13 are compared, the detection value ΔC of (2) of the second detection electrode 12 is larger. Therefore, it can be seen that the position of the head 49 of the occupant 48 is close to the lower vicinity (that is, the right side) of the second detection electrode 12. That is, by comparing the detection values ΔC of the first to third detection electrodes 11 to 13 in this way, it can be seen that the seating posture of the occupant 48 is in front of the right side of the seat 40 in this case.

  On the other hand, as shown in FIG. 3B, for example, an occupant 48 leans against the seat 40 in a normal state and sits in the center (that is, sits in a normal basic posture that matches the shape of the seat 40). The detection value ΔC of (2) of the second detection electrode 12 and (3) of the third detection electrode 13 is larger than the detection value ΔC of (1) of the first detection electrode 11. For this reason, it can be seen that the position of the head 49 of the occupant 48 is close to the lower side of the second detection electrode 12 and the third detection electrode 13 (that is, the rear of the seat 40).

  Further, when the detection value ΔC of (2) of the second detection electrode 12 and the detection value ΔC of (3) of the third detection electrode 13 are compared, these detection values ΔC are substantially equal to each other. It can be seen that the position of the head 49 is below the midpoint between the second and third detection electrodes 12 and 13 (that is, the head 49 is seated at the center position leaning on the seat 40).

  Thus, since the distance from each detection electrode 11-13 to the head 49 of the passenger | crew 48 can be calculated | required using each detection value (DELTA) C, the position of the head 49 is known using a known triangulation method etc. Can be calculated. However, since the relationship between the detected value ΔC and the distance of the head 49 also depends on the size of the head 49 of the occupant 48, the distance to the vehicle interior ceiling 2, and the like, the occupant posture detection according to the present embodiment. In addition to the above-described triangulation method, the apparatus 100 performs the following processing to accurately calculate the position of the head 49.

  That is, the occupant posture detection device 100 of the present embodiment performs the following arithmetic processing so that the position of the head 49 can be accurately detected even if the size of the head 49 changes, for example. ing. First, the front-rear position of the head 49 obtained by the above-described operation is stored as a parameter in storage means such as a RAM or ROM (not shown) provided in the circuit unit 20. Note that the detection value ΔC is a correction calculation using an equation where correction value = detection value of electrode 12 / (detection value of electrode 12 + detection value of electrode 13) for simplification of processing and accurate position detection. Used for processing.

  For example, as shown in FIG. 4A, when the head 49 of the occupant 48 seated on the seat 40 swings in the left-right direction (for example, the X direction), the left / right direction (X direction) of the head 49 of the occupant 48 And the correction value (normalized detection value (left and right)) calculated based on the detection value ΔC of the second and third detection electrodes 12 and 13 as in the graph shown in FIG. Even if there is a deviation in the detected value due to a difference in position in the front-rear direction, it is approximately expressed. As shown in FIGS. 3 (a) and 3 (b), when the detection electrodes 11 to 13 are linearly connected, the detection electrodes are formed into an isosceles triangle having the first detection electrode 11 as a vertex on the front side. In the occupant posture detection device in which 11 to 13 are arranged, as shown in FIG. 4B, the above-described normalized detection values (left and right) are less affected by the difference in the position of the head 49 in the front-rear direction.

  Next, information on the position in the left-right direction determined in this way is stored as a parameter as described above, and correction value = (detection value of electrode 11 / {detection value of electrode 11) using detection value ΔC. + (Detection value of electrode 12 + detection value of electrode 13) / 2}) is performed. For example, as shown in FIG. 5A, when the head 49 of the occupant 48 seated on the seat 40 swings in the front-rear direction (for example, Y direction), the front-rear direction (Y direction) of the head 49 of the occupant 48 The relationship between the position and the correction value (normalized detection value (front and back)) calculated based on the detection value ΔC of each of the detection electrodes 11 to 13 is represented as a graph shown in FIG. As shown in FIGS. 3 (a) and 3 (b), when the detection electrodes 11 to 13 are linearly connected, the detection electrodes are formed into an isosceles triangle having the first detection electrode 11 as a vertex on the front side. In the occupant posture detection device in which 11 to 13 are arranged, as shown in FIG. 5B, the above-described normalized detection value (front and back) is the difference in the horizontal position of the head 49 (for example, rightward). , Center, left side, etc.). However, the position in the front-rear direction of the head 49 can be accurately determined by reflecting the normalized detection value (front-rear) after determining the position in the left-right direction based on the result described with reference to FIG. .

  Instead of the triangulation method described with reference to FIG. 3, the correction calculation process based on the above-described theoretical formula is adopted as the main process for detecting the head 49 (the head of the head), and the head of the head 49 is directly detected. You may comprise so that a position may be detected. This is preferable because the top of the head closer to the “point” than the head 49 can be directly detected and the position can be obtained more accurately while reducing processing.

  The occupant posture detection device 100 according to the present embodiment connects the first to third detection electrodes 11 to 13 to one capacitance detection circuit 21 via the changeover switches SW1 to SW3, and performs switching control from the CPU 29. The change-over switches SW1 to SW3 are switched by the above, and the sitting posture of the occupant 48 is determined using the capacitance value detected by each of the detection electrodes 11 to 13. For example, each of the detection electrodes 11 to 13 is statically You may comprise so that the capacitance detection circuit 21 may be comprised. However, in this case, each capacitance detection circuit must be synchronized because the potential of other detection electrodes changes when the capacitance is detected (measured) by one detection electrode. There is.

  Here, as shown in FIG. 6, the capacitance detection circuit 21 generates a pulse signal whose duty ratio changes according to the capacitance between the detection electrodes 11 to 13 and the head 49 and is smooth. Output a detection signal. That is, the duty ratio changes according to the capacitance C. For example, the duty signal depends on the trigger signal generation circuit 101 that outputs a trigger signal TG having a fixed period and the size of the capacitance C connected to the input terminal. A timer circuit 102 that outputs a pulse signal Po whose ratio changes is provided, and a low-pass filter (LPF) 103 that smoothes the pulse signal Po.

  The timer circuit 102 includes, for example, two comparators 201 and 202, and an RS flip-flop circuit (hereinafter referred to as “RS-FF”) in which outputs of the comparators 201 and 202 are input to a reset terminal R and a set terminal S, respectively. 203), a buffer 204 that outputs the output DIS of the RS-FF 203 to the LPF 103, and a transistor 205 that is turned on / off by the output DIS of the RS-FF 203.

  The comparator 202 compares the trigger signal TG as shown in FIG. 7 output from the trigger signal generation circuit 101 with a predetermined threshold value Vth2 divided by the resistors R1, R2, and R3, and generates a trigger signal TG. Output synchronized set pulse. This set pulse sets the Q output of the RS-FF 203.

  This Q output turns off the transistor 205 as a discharge signal DIS, between the detection electrodes 11 (12, 13) and the ground, between the capacitance C to the ground of these detection electrodes and between the input terminal and the power supply line. Charging is performed at a speed determined by the time constant of the connected resistor R4. As a result, the potential of the input signal Vin increases at a speed determined by the capacitance C.

  When the input signal Vin exceeds the threshold value Vth1 determined by the resistors R1, R2, and R3, the output of the comparator 201 is inverted and the output of the RS-FF 203 is inverted. As a result, the transistor 205 is turned on, and the charge accumulated in the detection electrode 11 (12, 13) is discharged through the transistor 205.

  Therefore, the timer circuit 102, as shown in FIG. 7, has a pulse signal Po that oscillates at a duty ratio based on the capacitance C between the sensing electrode 11 (12, 13) and the head 49 of the approaching human body 48. Is output. The LPF 103 smoothes the output to output a DC detection signal Vout as shown in FIG. In FIG. 7, the waveform indicated by the solid line and the waveform indicated by the dotted line indicate that the former has a smaller capacitance than the latter, and for example, the latter indicates an object approaching state.

  In the occupant posture detection device 100 according to the above-described embodiment, the capacitance detection is performed as the configuration of the circuit unit 20 that determines the sitting posture using the position of the head 49 of the human body 48 based on the detected capacitance. The circuit 21 is described using a circuit that uses a well-known CV conversion type timer IC that converts a capacitance C (Capacitance) in which a duty ratio of an output pulse is changed by a resistor and a capacitor into a voltage V (Voltage). However, the present invention is not limited to this.

  That is, for example, a method in which a sine wave is applied to directly measure impedance from a voltage change or current value due to a capacitance value, a method in which an oscillation circuit is configured to include the capacitance to be measured, and a oscillation frequency is measured. Configure the discharge circuit to measure the charge / discharge time, move the charge charged at a known voltage to a known capacity and measure the voltage, or charge an unknown capacity at a known voltage and charge the charge There is a method of measuring the number of times until the known capacity is charged to a predetermined voltage by moving to the known capacity multiple times, and setting a threshold value for the detected capacitance value, or a signal waveform of the capacitance It may be made to function as a switch by performing a process such as triggering when a corresponding capacitance waveform is obtained by analyzing the above.

  In this embodiment, it is assumed that the capacitance detection circuit 21 detects the capacitance by converting the capacitance into a voltage by the CV conversion type. However, the data is easy to handle electrically or as software. For example, it may be converted into a pulse width or directly into a digital value.

  Furthermore, in the present embodiment, the capacitance detection circuit 21 has been described using a CV conversion type, but for example, the following may be used.

  FIG. 8 is an explanatory diagram illustrating another example of a partial configuration of the occupant posture detection device according to the embodiment of the present invention. As shown in FIG. 8, the capacitance detection circuit 21 of this example is configured as a differential operation type, and can cancel the temperature characteristics in the circuit while removing common mode noise. Here, an example of a differential operation type circuit that employs a method of measuring the voltage by moving the charge charged at a known voltage to a known capacitance will be described.

  First, for example, the first detection electrode 11 is connected to the plus-side input end, the second and third detection electrodes 12 and 13 are connected to the minus-side input end, and the capacitance C1 of the detection electrode 11 to the detection electrode 12, Alternatively, the total value of the 13 electrostatic capacitances C2 + C3 may be subtracted, and the output value may be compared with a threshold value by a comparator or the like to detect the position of the head 49. Naturally, the position of the head 49 in the front-rear direction and the left-right direction can be detected by changing the configuration of the detection electrodes connected to the plus-side input end and the minus-side input end.

  As an example of the operation of the electrostatic capacitance detection circuit 21, for example, when the switch S1 is open (OFF), the switch S2 is grounded (GND), and the switch S3 is closed (ON), When S3 is opened (OFF), the switch S2 is switched to Vr, and the switch S1 is connected to the inverting input of the operational amplifier, the capacitances C1 and Cf are charged with C1Vr, and the capacitances C2, C3, and Cf are (C2 + C3). Vr is charged.

  Then, after the switch S1 is opened (OFF) and the switch S2 is grounded (GND), the voltage V when the switch S1 is grounded (GND) is measured. The voltage at this time is, for example, V / Vr = {(Cf + C1) / Cf} − {(Cf + C2 + C3) / Cf}, and a voltage corresponding to the ratio between the capacitance C1 and the capacitance C2 + C3 is output. . Thereby, the position of the head 49 can be detected similarly.

  In many cases, a metal member is used for the interior of the passenger compartment ceiling 2 of the vehicle 1 or the seat 40. When the seat 48 is moved and the occupant 48 changes its posture, each of the detection electrodes 11-13. The positional relationship between the vehicle and the occupant 48 changes, and the capacitance value due to such a change in the external environment may be detected, leading to a malfunction.

  In order to avoid such influence as much as possible, although not shown in the drawing, an auxiliary electrode (shield electrode) that suppresses the change in electrostatic capacitance is provided with each of the detection electrodes 11 to 19 together with the shield portions 18 and 19 described above. You may make it provide in the vicinity position of 13.

  In this case, each shield electrode only needs to have a potential equivalent to that of the first to third detection electrodes 11 to 13. Similar to the case of the shield drive circuit 23, the equivalent potential may be generated through a single amplifier (buffer) with a high input impedance from the potential applied to each of the detection electrodes 11 to 13, for example. In the case of the capacitance detection circuit 21 shown in FIG. 8, the non-inverting input portion of the operational amplifier may be connected to the shield electrode.

  FIG. 9 is an explanatory diagram for explaining another example of a partial configuration of the occupant posture detection device according to the embodiment of the present invention. In the following description, the same parts as those already described are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 9, here, a right first detection electrode 11 a and a left first detection electrode 11 b are provided, and when the detection electrodes 11 a, 11 b, 12, 13 are connected in a straight line, the vehicle 1 front-rear direction And the point arrange | positioned in the compartment ceiling part 2 in the rectangular planar shape which forms a side in the left-right direction is different from the previous example.

  In this way, the seating posture of the human body 48 can be determined based on the position of the head 49 of the human body 48 seated on the seat 40 with higher accuracy. Although four detection electrodes are used here, for example, even if the number of detection electrodes is five or more, the detection accuracy can be improved to some extent in terms of cost. is there. Moreover, the arrangement | positioning aspect mainly demonstrated using FIGS. 3-5 can also be changed so that it may become an isosceles triangle so that the detection electrode 11 may become one vertex of the back side, for example.

  As described above, the occupant posture detection device 100 according to the present embodiment has a very simple and inexpensive configuration of the capacitance sensor unit 10 and the circuit unit 20 including the detection electrodes 11 to 13 and the like, with high accuracy. The posture (sitting posture) of the occupant 48 can be detected, and the posture information can be used for airbag deployment control and the like.

It is explanatory drawing which shows an example of the whole structure of the passenger | crew attitude | position detection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows an example of the detection electrode of the passenger | crew attitude | position detection apparatus. It is explanatory drawing for demonstrating an example of the operation principle of the passenger | crew attitude | position detection apparatus. It is explanatory drawing for demonstrating the determination operation | movement of the left-right direction of the passenger | crew attitude | position detection apparatus. It is explanatory drawing for demonstrating the determination operation | movement of the front-back direction of the said passenger | crew attitude | position detection apparatus. It is a block diagram which shows an example of the electrostatic capacitance detection circuit of the passenger | crew attitude | position detection apparatus which concerns on one Embodiment of this invention. It is an operation | movement waveform diagram which shows an example of the operation | movement waveform of the circuit part of the passenger | crew attitude | position detection apparatus. It is explanatory drawing which shows the other example of a partial structure of the passenger | crew attitude | position detection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating the other example of a partial structure of the passenger | crew attitude | position detection apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Vehicle compartment ceiling part, 10 ... Capacitance sensor part, 11 ... 1st detection electrode, 11a ... Right side 1st detection electrode, 11b ... Left side 1st detection electrode, 12 ... 2nd detection electrode, 13 3rd detection electrode 18, 19 ... Shield part, 20 ... Circuit part, 21 ... Capacitance detection circuit, 22 ... A / D converter, 23 ... Shield drive circuit, 29 ... CPU, 40 ... Seat, 48 ... Human body, 49... Head, 100.

Claims (12)

At least three are arranged on the ceiling of the passenger compartment above the seat of the vehicle so that a position on a predetermined plane can be detected, and a static space between the head of the human body seated on the seat and the ceiling of the passenger compartment. A sensing electrode for detecting the capacitance;
A detection circuit connected to each of the detection electrodes and detecting the position of the head of the human body based on a detection signal from each detection electrode;
A posture determination circuit for determining a sitting posture of the human body according to a detection result from the detection circuit ;
The detection circuit detects the position of the head of the human body directly from the capacitance value of each detection electrode, and then corrects the correction value in the X direction of the position of the head and the Y direction of the position of the head. The occupant is characterized in that a correction value is obtained from the capacitance value of each detection electrode, and a correction calculation process required for determining the seating posture of the human body is further performed in the posture determination circuit based on the correction value. Attitude detection device. The detection circuit is connected to the detection electrode via a changeover switch,
A drive circuit connected to each of the detection electrodes via the changeover switch and outputting a predetermined voltage to each detection electrode;
The posture determination circuit switches the changeover switch so that when one detection electrode of the detection electrodes is alternatively connected to the detection circuit, the other detection electrode is connected to the drive circuit. The occupant posture detection device according to claim 1, wherein the operation is controlled. Said posture determination circuit, information about the decision to the human body sitting posture, the passenger according to claim 1 or 2, and outputs to the ECU which includes a function of controlling the deployment of the air bag mounted in the vehicle Attitude detection device. The occupant according to any one of claims 1 to 3 , wherein the detection electrode is disposed on the ceiling of the passenger compartment in a triangular plane shape having one apex on the front side of the vehicle. Attitude detection device. The occupant according to any one of claims 1 to 3 , wherein the detection electrode is disposed on the ceiling of the passenger compartment in a triangular plane shape having one apex on the rear side of the vehicle. Attitude detection device. The sensing electrode, any one of claims 1 to 3, characterized in that it is four arranged in the casing ceiling in a square planar shape so as to form an edge respectively in the longitudinal direction and the lateral direction of the vehicle The occupant posture detection device according to claim 1. The occupant posture according to any one of claims 1 to 6 , further comprising a shield portion that is electrically insulated from the detection electrode on or on the back side and / or the periphery of the detection electrode. Detection device. The occupant posture detection device according to claim 7 , wherein the shield portion is given the same potential as that of the detection electrode. The detection circuit includes storage means for storing a capacitance value when a human body is not seated in the seat in advance, and when the human body is seated, from the capacitance value stored in the storage means. The occupant posture detection device according to any one of claims 1 to 8 , wherein a detection result is output using the increase amount as a detection value. The detection circuit of any one of claims 1-9, characterized in that it comprises a capacitance sensing circuit of the C-V conversion type which converts the capacitance sensed by the sensing electrode into a voltage Crew attitude detection device. The detection circuit has a differential operation type capacitance detection circuit, and an auxiliary electrode connected to the input terminal of the capacitance detection circuit having a phase opposite to that of the detection electrode is arranged in the vicinity of each detection electrode. The occupant posture detection device according to any one of claims 1 to 9 , wherein the occupant posture detection device is provided. Between the head of the human body seated on the seat and the ceiling of the passenger compartment by means of at least three detection electrodes provided on the ceiling of the passenger compartment above the seat of the vehicle so that the position on the plane can be detected. Detecting the capacitance of
Based on the detection signal from each detection electrode indicating the detected capacitance, the position of the head of the human body is directly detected from the capacitance value of each detection electrode, and the position of the head of the human body is detected. Then, a correction value in the X direction of the position of the head and a correction value in the Y direction of the position of the head are obtained from the capacitance values of the detection electrodes, and further based on the correction values, the human body Correction calculation required to determine the sitting posture of the
An occupant posture detection method, wherein the seating posture of the human body is determined by reflecting the result of the correction calculation on the basis of the detected position of the head.

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