JP2010237144A - Obstacle detection device for vehicle, and airbag deployment control device for protecting pedestrian - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and positively detect obstacles to vehicles such as automobiles. <P>SOLUTION: An obstacle detection device for vehicles includes capacitance sensors 10-30 disposed on a front bumper 2 of a vehicle 1; and a circuit 50. An airbag deployment controller for protecting pedestrians includes a control unit 60; a pedestrian protecting device 70; and airbags for protecting pedestrians 81-83. The airbags for protecting pedestrians 81-83 are disposed so that the rear end side of a hood 3 at a position corresponding to the capacitance sensors 10-30 can flip up. The capacitance sensors 10-30 include a sensor electrode 11; a shield electrode 12; and an auxiliary electrode 13. The directivity is set using a first capacitance value C1 detected only by the sensor electrode 11 and the second capacitance value C2 detected by the sensor electrode 11 and the auxiliary electrode 13, detection zones Z1-Z3 are formed on the surface of the capacitance sensors 10-30, and obstacles are detected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle obstacle detection device that detects an obstacle to a vehicle such as an automobile, and a pedestrian protection airbag deployment control device.

  As a device for determining an obstacle collision with a vehicle such as an automobile, for example, a vehicle collision determination device (see, for example, Patent Document 1 (pages 3-7 and 1-17)) is known. The vehicle collision determination apparatus includes a collision detection unit that detects a collision by deformation of the collision surface of the vehicle, and a collision target estimation unit that estimates a collision target based on an output signal from the collision detection unit.

  The collision detection means includes a counter electrode disposed on the collision surface at a predetermined interval, and an elastic dielectric interposed between the counter electrodes, and detects a change in capacitance caused by the collision. It consists of a capacitive collision detection sensor unit that outputs electrical signals. The collision target estimation unit includes a determination unit that determines the collision target from the strength of the collision by comparing the electric signal from the collision detection unit with the data on the map prepared for each vehicle speed in advance.

  Further, as a sensor that detects the proximity of an obstacle, for example, a capacitive sensor (see, for example, Patent Document 2 (pages 17-32 and FIGS. 1-11)) is known. This capacitive sensor is attached to a bumper of a vehicle, measures the capacitance between the sensor plate and the ground (GND), and detects the proximity of an obstacle to the vehicle.

JP 2000-177514 A Japanese translation of PCT publication No. 2003-506671

  However, in the vehicle collision determination device disclosed in Patent Document 1 described above, the obstacle is detected by the obstacle actually colliding with the vehicle. Therefore, the obstacle is detected prior to the collision. There is a problem that can not be. Further, the capacitive sensor disclosed in Patent Document 2 described above has a problem in that an obstacle may be erroneously detected due to factors such as road surface unevenness and the size of the obstacle.

  In order to solve the above-described problems caused by the prior art, the present invention provides a vehicle obstacle detection device and a pedestrian protection airbag deployment control device capable of accurately and reliably detecting an obstacle to a vehicle such as an automobile. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, an obstacle detection device for a vehicle according to the present invention includes a plurality of capacitance sensors arranged on a bumper of a vehicle so that a detection surface exists toward the front of the vehicle. The capacitance sensor unit includes a sensor electrode and an auxiliary electrode provided in the vicinity of the sensor electrode, and at least the sensor electrode is connected to the capacitance from the connected electrode. A detection circuit for detecting a capacitance value based thereon, a first connection state in which the auxiliary electrode is not connected to the detection circuit, and a second connection state in which the auxiliary electrode is connected to the detection circuit are selectively switched The possible changeover switch, the first capacitance value from the detection circuit in the first connection state, and the second capacitance value from the detection circuit in the second connection state were compared. Comparison value and Based on the first or second capacitance value, obstacle, comprising the determining means for determining whether or not there is within the detection range on the sensor electrode.

  The change-over switch is configured to be able to open, connect to the ground, or to a predetermined potential, for example, when the auxiliary switch is in the first connection state.

  The shield switch further includes a shield drive circuit that applies a potential equivalent to the sensor electrode to the auxiliary electrode, and the changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit, for example, in the first connection state. ing.

  The obstacle detection device for a vehicle according to the present invention includes a plurality of capacitance sensor units arranged on a bumper of a vehicle so that a detection surface exists in front of the vehicle, and the capacitance sensor unit Is composed of a sensor electrode and an auxiliary electrode provided in the vicinity of the sensor electrode, a detection circuit for detecting a capacitance value based on the capacitance from the sensor electrode, and the sensor electrode on the auxiliary electrode. A shield drive circuit that applies an equivalent potential, a first connection state in which the auxiliary electrode is connected to the shield drive circuit, and a second connection state in which the auxiliary electrode is opened, grounded, or connected to a predetermined potential are selected. A changeable switch, a first capacitance value from the detection circuit in the first connection state, and a second capacitance value from the detection circuit in the second connection state Compare Comparison value, and based on said first or second capacitance value, obstacle, comprising the determining means for determining whether or not there is within the detection range on the sensor electrode.

  Furthermore, the vehicle obstacle detection device according to the present invention has a plurality of capacitance sensor units arranged on a bumper of a vehicle so that a detection surface exists in front of the vehicle, and the capacitance sensor unit Comprises a sensor electrode and an auxiliary electrode provided in the vicinity of the sensor electrode, and detects a capacitance value based on the capacitance from the connected electrode; and the sensor electrode as the detection circuit A first changeover switch that can selectively switch between a first connection state connected to the sensor circuit and a second connection state where the sensor electrode is not connected to the detection circuit, and the sensor electrode is in the first connection state. A second change-over switch that is switchable to connect the auxiliary electrode to the detection circuit when the first change-over switch is in the second connection state without connecting the auxiliary electrode to the detection circuit. The first A comparison value comparing a first capacitance value from the detection circuit in the connection state with a second capacitance value from the detection circuit in the second connection state, and the first And determining means for determining whether an obstacle is within a detection range on the sensor electrode based on the first or second capacitance value.

  The first changeover switch is configured to be able to open, connect to the ground or a predetermined potential of the sensor electrode in the second connection state, for example, and the second changeover switch is, for example, in the first connection state. Sometimes, the auxiliary electrode is open, grounded, or connectable to a predetermined potential.

  A shield driving circuit that applies a potential equivalent to the sensor electrode to the auxiliary electrode or a potential equivalent to the auxiliary electrode to the sensor electrode; and the first changeover switch is, for example, in the second connection state Sometimes the sensor electrode is configured to be connectable to the shield drive circuit, and the second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit, for example, in the first connection state. .

  A shield driving circuit for applying a potential equivalent to that of the sensor electrode to the auxiliary electrode is further provided, and the first changeover switch opens the auxiliary electrode, for example, is connected to ground or a predetermined potential in the second connection state. The second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state, for example.

  A shield driving circuit for applying a potential equivalent to that of the auxiliary electrode to the sensor electrode is further provided, and the first changeover switch is configured to be able to connect the auxiliary electrode to the shield driving circuit in the second connection state, for example. For example, the second changeover switch is configured to be able to open the auxiliary electrode, connect to the ground, or to a predetermined potential in the first connection state.

  The auxiliary electrode is disposed, for example, so as to surround the sensor electrode.

  A pedestrian protection airbag deployment control device according to the present invention is detected by the vehicle obstacle detection device according to the invention described above, travel state detection means for detecting the travel state of the vehicle, and the vehicle obstacle detection device. And a deployment control means for controlling the deployment of the pedestrian protection airbag disposed on the hood of the vehicle based on the detected result and information indicating the running condition detected by the running condition detecting means. It is characterized by that.

  The deployment control means determines, for example, whether the obstacle detected by the vehicle obstacle detection device is a human body, indicates that the obstacle is a human body, and indicates whether the obstacle is a human body. When it is detected that the vehicle is in a predetermined running state, the pedestrian protection airbag is deployed according to the predetermined running state.

  Further, a plurality of the pedestrian protection airbags are arranged, for example, on the hood of the vehicle, and the deployment control means detects the position of the obstacle detected based on, for example, a detection result from the vehicle obstacle detection device. And the deployment of the airbag for protecting pedestrians at the corresponding arrangement position along the front-rear direction of the vehicle is controlled according to the position of the obstacle.

  The pedestrian protection airbag is disposed, for example, such that the rear end side of the hood of the vehicle can be flipped up or the surface of the hood of the vehicle can be covered.

  ADVANTAGE OF THE INVENTION According to this invention, the obstacle detection apparatus for vehicles which can detect the obstruction with respect to vehicles, such as a motor vehicle correctly and reliably, and the airbag deployment control apparatus for pedestrian protection can be provided.

It is explanatory drawing which shows the example of the whole structure of the airbag deployment control apparatus for pedestrian protection provided with the obstacle detection apparatus for vehicles concerning one Embodiment of this invention. It is explanatory drawing for demonstrating the example of arrangement | positioning in the vehicle of the airbag deployment control apparatus for the said pedestrian protection. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the operation | movement concept at the time of the detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object at the time of the detection operation | movement of the obstacle detection apparatus for vehicles, and an electric force line. It is explanatory drawing for demonstrating the operation | movement concept at the time of the detection operation | movement of the obstacle detection apparatus for vehicles. It is a flowchart which shows the example of the expansion control processing procedure of the pedestrian protection airbag by the pedestrian protection airbag expansion control device. It is explanatory drawing which shows the other example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstacle detection apparatus for vehicles. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstruction detection apparatus for vehicles concerning other embodiment of this invention. It is a flowchart which shows the example of the deployment control processing procedure of the airbag for pedestrian protection by the airbag deployment control apparatus for pedestrian protection provided with the obstacle detection apparatus for vehicles. It is explanatory drawing which shows the other example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstacle detection apparatus for vehicles. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstruction detection apparatus for vehicles concerning other embodiment of this invention. It is explanatory drawing for demonstrating the operation | movement concept at the time of the detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object and electric flux of force at the time of 1st detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object and electric flux of force at the time of 1st detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object and electric flux of force at the time of 1st detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing for demonstrating the relationship between the detection target object and electric force line at the time of the 2nd detection operation | movement of the obstacle detection apparatus for vehicles. It is explanatory drawing which shows the example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstruction detection apparatus for vehicles concerning other embodiment of this invention. It is explanatory drawing which shows the other example of the whole structure of the electrostatic capacitance sensor part and circuit part of the obstacle detection apparatus for vehicles.

  Exemplary embodiments of a vehicle obstacle detection device and a pedestrian protection airbag deployment control device according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is an explanatory diagram showing an example of the overall configuration of a pedestrian protection airbag deployment control device including a vehicle obstacle detection device according to an embodiment of the present invention, and FIG. 2 shows the pedestrian protection airbag. FIG. 3 is an explanatory diagram for explaining an example of the arrangement of the deployment control device in the vehicle, and FIG. 3 is an explanatory diagram showing an example of the overall configuration of the capacitance sensor unit and the circuit unit of the vehicle obstacle detection device.

  As shown in FIG. 1 and FIG. 2, the vehicle obstacle detection device according to the present embodiment is, for example, a first bumper 2 disposed in a front bumper 2 of a vehicle 1 such that a detection surface exists toward the front of the vehicle 1. The capacitance sensor unit 10, the second capacitance sensor unit 20, and the third capacitance sensor unit 30 are provided.

  As shown in FIG. 2B, each of the capacitance sensor units 10 to 30 can detect, for example, a pedestrian in front of the vehicle 1 (for example, a pedestrian's foot 49), for example, FIG. And as shown to Fig.2 (a), the 1st electrostatic capacitance sensor part 10 is on the left side (right side of the vehicle 1) toward the front bumper 2, and the 2nd electrostatic is on the center side (center side of the vehicle 1). The capacitance sensor unit 20 is further arranged so that the third capacitance sensor unit 30 is located on the right side (left side of the vehicle 1).

  Further, the vehicle obstacle detection device, as shown in FIG. 2 (b), on the basis of the outputs from these capacitance sensor units 10-30, the foot 49 is placed on each capacitance sensor unit 10-30. The circuit unit 50 is configured to determine whether or not it is within the detection ranges Z1, Z2, and Z3. Information regarding the detection result of the vehicle obstacle detection device output by the circuit unit 50 is output to the control unit 60 of the pedestrian protection airbag deployment control device.

  The control unit 60 of the pedestrian protection airbag deployment control device is arranged on the hood 3 of the vehicle 1 based on the information from the circuit unit 50 and the information indicating the detected traveling state of the vehicle 1 from the vehicle speed sensor 90. A deployment control signal for controlling the deployment of the pedestrian protection airbags 81 to 83 is output to the pedestrian protection device 70. The pedestrian protection device 70 actually deploys the pedestrian protection airbags 81, 82, 83 disposed on the hood 3 of the vehicle 1 based on the deployment control signal from the control unit 60.

  As shown in FIG. 2A, the pedestrian protection airbags 81 to 83 are arranged on the left side (vehicles) toward the hood 3 so that the rear end side of the hood 3 of the vehicle 1 can be flipped up, for example. 1 is a first pedestrian protection airbag 81 on the center side (center side of the vehicle 1), and a second pedestrian protection airbag 82 is on the right side (left side of the vehicle 1). The third pedestrian protection airbag 83 is disposed so as to be positioned.

  In the pedestrian protection airbag deployment control device of this example, for example, when the vehicle 1 is in a predetermined traveling state (for example, a state where the vehicle is moving forward at a speed of 5 km / h or more), the first obstacle detection device for the vehicle is used. When it is detected by the one capacitance sensor unit 10 that the foot 49 is within the detection range Z1, control is performed so that the first pedestrian protection airbag 81 is deployed.

  Similarly, when the second capacitance sensor unit 20 of the vehicle obstacle detection device detects that the foot 49 is within the detection range Z2, the second pedestrian protection airbag 82 is When the capacitance sensor unit 30 detects that the foot 49 is within the detection range Z3, control is performed so that the third pedestrian protection airbag 83 is deployed.

  As shown in FIGS. 1 and 2, in this example, each of the capacitance sensor units 10 to 30 is arranged in the front bumper 2 along the width direction of the vehicle 1. An electrostatic capacitance sensor unit may be arranged. Further, when a license plate (not shown) is attached to the front bumper 2, for example, the second capacitance sensor unit 20 may be arranged in a state in which the detection range Z2 can be formed in a shape that avoids the license plate.

  As shown in FIG. 3, each of the capacitance sensor units 10 to 30 is configured such that the detection ranges Z1 to Z3 exist in the detection area on the detection surface side facing the front of the vehicle 1 and is formed in a rectangular belt shape. A sensor electrode 11, a shield electrode 12 formed on the back side of the sensor electrode 11, and an auxiliary electrode 13 formed on the same plane as the sensor electrode 11 and formed in a hollow long frame shape surrounding the sensor electrode 11; Are each provided.

  The sensor electrode 11 and the auxiliary electrode 13 are disposed so as to be insulated from each other. The shield electrode 12 is preferably larger than the sensor electrode 11 in order to reduce the sensor sensitivity on the back side.

  The sensor electrode 11 detects a detection object (pedestrian's foot 49) within the detection range Z1 to Z3 of the detection area on the detection surface side. The shield electrode 12 shields them from being detected on the back side of the sensor electrode 11. The auxiliary electrode 13 is for changing the equicapacitance line (surface) on the detection surface side of the sensor electrode 11 so that each of the capacitance sensor units 10 to 30 has directivity. In addition, the shield electrode 12 may be provided in the outer peripheral side of the auxiliary electrode 13 together with the aspect mentioned above, for example.

  The circuit unit 50 is connected to each of the capacitance sensor units 10 to 30 and includes, for example, a CV conversion circuit 21 directly connected to the sensor electrode 11, an A / D converter 22, and a CPU 23. ing. Here, a shield drive circuit 12 is further provided, and a changeover switch SW for switching the connection of the auxiliary electrode 13 between the CV conversion circuit 21 and the shield drive circuit 24 is provided.

  The CV conversion circuit 21 converts a capacitance detected by the sensor electrode 11 or the sensor electrode 11 and the auxiliary electrode 13 into a voltage (Voltage). The A / D converter 22 converts an analog signal indicating a voltage from the CV conversion circuit 21 into a digital signal.

  The CPU 23 controls the entire vehicle obstacle detection device and controls the changeover switch SW, determines the detection (presence / absence) of the detection object (foot 49) in the detection range Z1 to Z3 of the detection area, A signal related to the determination result is output to the control unit 60. The shield drive circuit 24 drives, for example, the shield electrode 12 and the auxiliary electrode 13 to the same potential as the sensor electrode 11.

  The circuit unit 50 includes a storage unit (not shown) such as a RAM used as a temporary storage area of the CPU 23 and a ROM for storing data. Moreover, each electrostatic capacitance sensor part 10-30 is formed on the board | substrate which is not shown in figure, for example. As this board | substrate, any board | substrate of a flexible printed circuit board, a rigid board | substrate, and a rigid flexible board | substrate is employable, for example.

  Furthermore, the circuit unit 50 may be mounted and integrally provided on the same surface side or the back surface side of the substrate on which the capacitance sensor units 10 to 30 are formed. In this case, a plurality of circuit units 50 may be provided so as to correspond to the number of capacitance sensor units 10 to 30.

  The sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13 are substrates made of an insulator such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyamide (PA), glass epoxy resin, or ceramic. It can be composed of copper, a copper alloy, a metal member (conductive material) such as aluminum or iron, an electric wire, or the like patterned on top.

  In addition, depending on the arrangement mode of each of the capacitance sensor units 10 to 30 (for example, when arranged on the surface side of the front bumper 2), it may be necessary to arrange the capacitance sensor units 10 to 30 so that they are not conspicuous in appearance. In such a case, the substrate may be formed of a transparent panel or film, and the electrodes 11 to 13 may be transparent electrodes.

  The transparent electrode can be composed of, for example, tin-doped indium oxide (ITO) or a conductive polymer. As the conductive polymer, for example, PEDOT / PSS (polyethylene dioxythiophene / polystyrene sulfonic acid), PEDOT / TsO (polyethylene dioxythiophene / toluene sulfonate), or the like can be used.

  Next, the detection operation of the detection target (foot 49) of the vehicle obstacle detection device configured as described above will be described. First, an operation (operation 1) when the changeover switch SW is connected to the shield drive circuit 24 side under the control of the CPU 23 will be described. In the case of this operation 1, the connection state between the sensor electrode 11, the shield electrode 12, the auxiliary electrode 13, and the circuit unit 20 of each of the capacitance sensor units 10 to 30 is as shown in FIG.

  That is, only the sensor electrode 11 is connected to the CV conversion circuit 21, and the shield electrode 12 and the auxiliary electrode 13 are connected to the shield drive circuit 24. The capacitance C with B is detected by the CV conversion circuit 21. At this time, the back surface side of the sensor electrode 11 is covered with the shield electrode 12 connected to the shield drive circuit 24. For this reason, the sensor sensitivity on the back surface side of the sensor electrode 11 is almost equal, and this is also the case with the operation 2 described later.

  Further, both detection objects A and B are at substantially the same distance from the sensor electrode 11. However, due to the influence of the auxiliary electrode 13 connected to the shield drive circuit 24, the above-described equal capacitance line (surface) M is in a state as shown in FIG. Lower than the sensor sensitivity to.

  In this case, as shown in FIG. 5A, the electric lines of force P1 from the sensor electrode 11 with respect to the detection object A existing near the center of the sensor electrode 11 are the electric lines of force P2 from the auxiliary electrode 13 (shield). ) Is small. However, as shown in FIG. 5B, the electric lines of force P <b> 1 from the sensor electrode 11 to the detection target B existing outside the sensor electrode 11 are the electric lines of force P <b> 2 (shield) from the auxiliary electrode 13. It can be said that it is easily affected.

  For this reason, in the operation 1, both the detection objects A and B exist at the same distance from the sensor electrode 11, but the capacitance value detected by the CV conversion circuit 21 is the detection object of the detection object A. It becomes larger than the object B. The first capacitance value C1 detected during such operation 1 is stored in the storage unit by the CPU 23.

  In the case of this operation 1, by connecting the auxiliary electrode 13 to the shield drive circuit 24, the sensor at the electrode end (end on the auxiliary electrode 13 side) of the sensor electrode 11 with respect to the sensor sensitivity at the center of the sensor electrode 11 is detected. Sensitivity can be lowered. Thereby, it becomes possible to give each electrostatic capacitance sensor part 10-30 slight directivity.

  However, in this operation 1, the sensor sensitivity of the electrode end of the sensor electrode 11 is only slightly reduced. Therefore, for example, the capacitance value of the detection object C (see FIG. 4) which is the foot 49 located closer to the sensor electrode 11 than the detection object B shown in FIG. It becomes almost equal to the capacitance value. At this time, the equal capacitance line (surface) M is in a state as shown in FIG. For this reason, the difference between the detection objects A and C cannot be determined, and it must be said that this is a state in which a stronger directivity cannot be provided.

  Next, an operation (operation 2) when the changeover switch SW is connected to the CV conversion circuit 21 side under the control of the CPU 23 will be described. In the case of this operation 2, the connection state between the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13 of each of the capacitance sensor units 10 to 30 is as shown in FIG.

  That is, since the sensor electrode 11 and the auxiliary electrode 13 are connected to the CV conversion circuit 21, the capacitance between the detection objects A and B is changed by the CV conversion circuit 21 by the sensor electrode 11 and the auxiliary electrode 13. Detected. At this time, as described above, the sensor sensitivity on the back surface side of the sensor electrode 11 is almost equal, but the equivalent capacitance line (surface) M on the detection surface side (front surface side) of the sensor electrode 11 is in the state shown in FIG. Thus, it can be said that there is no directivity in the range of 180 ° on the detection surface side.

  For this reason, in the operation 2, substantially the same capacitance value is detected for both detection objects A and B existing at substantially the same distance from the sensor electrode 11. Then, the second capacitance value C2 detected during such operation 2 is stored in the storage means by the CPU 23 in the same manner as the first capacitance value C1.

  As described above, the operation 1 and the operation 2 described above can vary the equicapacitance line (surface) M on the detection surface side by the sensor electrode 11. Thus, the first capacitance value C1 detected when there is a slight directivity on the detection surface side of the sensor electrode 11 and the second capacitance detected when there is no directivity on the detection surface side of the sensor electrode 11. Is obtained.

  Thereafter, in the vehicle obstacle detection device of this example, the following operation is performed. First, the first capacitance value C1 stored in the storage means by the CPU 23 is compared with the second capacitance value C2. For example, in the case of the operation 2 described above, since the capacitance values detected from both the detection objects A and B are substantially the same value, the detection objects A and B are at an approximately equal distance from the sensor electrode 11. It turns out that there is.

  Next, in the case of the operation 1, since the electrostatic capacitance value of the detection target B is smaller than the detection target A, the detection target B should be outside the detection electrode A with respect to the sensor electrode 11. Becomes clear. Based on these considerations, the CPU 23 compares the second capacitance value C2 with the first capacitance value C1 to determine how much the detection target is outside the central portion of the sensor electrode 11. (That is, whether or not the detection target is within a predetermined range including at least a region facing the detection surface of the sensor electrode 11 (hereinafter, may be abbreviated as “in the detection range”)). ) Can be determined.

  According to the vehicle obstacle detection device configured and operated as described above, as shown in FIG. 1, each capacitance sensor unit disposed in the front bumper 2 by each capacitance sensor unit 10 to 30, for example. It can be determined whether or not there is a detection object (foot 49) or an object (such as a power pole or pole) within the detection ranges Z1 to Z3 formed on 10 to 30 (sensor electrode 11).

  These detection ranges Z1 to Z3 are determined by the set directivity. Further, the detected capacitance value when the foot 49 is within the detection range Z1 to Z3 can also be determined by the profile. Therefore, the foot 49 and the object can be discriminated by comparing the detected capacitance value using profile data as a threshold value or the like.

  Therefore, for example, even if there is a foot 49 or an object or an obstacle S (see FIG. 2B) outside the detection range Z1 to Z3 in front of the front bumper 2, these are not detected, and the object or obstacle Even if the object S is in the detection range Z1 to Z3, these are excluded, and the detection range Z1 to Z3 is defined as a sensor electrode so that it can be accurately determined whether or not the foot 49 is in the detection range Z1 to Z3. 11 is set in the area above.

  Then, based on the determination result, the control unit 60 of the pedestrian protection airbag deployment control device, for example, detects the foot 49 when the vehicle 1 is in the predetermined running state as described above. A deployment control signal for controlling the deployment of the pedestrian protection airbags 81 to 83 located at positions corresponding to the positions of the capacity sensor units 10 to 30 along the front-rear direction of the vehicle 1 is output to the pedestrian protection device 70. .

  Based on the deployment control signal from the control unit 60, the pedestrian protection device 70 immediately corresponds to at least one of the pedestrian protection airbags 81 to 83 disposed on the hood 3, that is, the corresponding one instructed by the deployment control signal. The air bag for protecting the pedestrian is deployed, and the corresponding position on the rear end side of the bonnet 3 is flipped up.

  Thereby, even when the vehicle 1 collides with a pedestrian (foot 49) while traveling in a predetermined traveling state, the impact when the pedestrian crashes into the hood 3 and is injured can be reduced. Safety at the time of collision can be improved. Note that the pedestrian protection airbags 81 to 83 may be deployed so as to cover (cover) the surface of the bonnet 3, for example, in addition to the one that flips up the rear end side of the bonnet 3.

  Here, the deployment control processing of the pedestrian protection airbag by the pedestrian protection airbag deployment control device provided with the vehicle obstacle detection device will be described. FIG. 7 is a flowchart showing an example of a procedure for the deployment control processing of the pedestrian protection airbags 81 to 83 by the pedestrian protection airbag deployment control device.

  As shown in FIG. 7, first, the vehicle obstacle detection device starts processing of the vehicle obstacle detection device, for example, triggered by the ignition switch of the vehicle 1 being turned on as an accessory or ON. Then, under the control of the CPU 23 of the circuit unit 50, the connection state of the auxiliary electrode 13 by the changeover switch SW is switched to the above-described first and second connection states.

  Thus, the capacitance values (first and second capacitance values C1 and C2) are detected in each of the capacitance sensor units 10 to 30 (step S101), and these are compared to calculate a comparison value ( Step S102).

  Then, based on the first capacitance value C1 or the second capacitance value C2, it is determined whether or not the detection target (obstacle) is close to the sensor electrode 11 (step S103). At the same time, it is determined whether or not the calculated comparison value is equal to or greater than a predetermined threshold value set in advance (or less than a predetermined threshold value or less than a predetermined threshold value, for example) (step S104).

  If it is determined that the obstacle is close (Y in step S103) and the comparison value is determined to be greater than or equal to a predetermined threshold (Y in step S104), the obstacle is determined to be detected. (Step S <b> 105), information related to the detection result including the determination result is output to the control unit 60.

  The control unit 60 of the pedestrian protection airbag deployment control device determines which of the capacitance sensor units 10 to 30 detects the obstacle based on the information about the detection result. Then, the position of the obstacle is specified (step S106).

  In step S106, the detected capacitance value is detected even if an obstacle is detected in a plurality of detection ranges among the detection ranges Z1 to Z3 of the capacitance sensor units 10 to 30. By performing arithmetic processing for specifying the position based on the position, the position can be specified.

  Then, once the position of the obstacle is identified, for example, referring to the profile data of the capacitance value stored in advance, whether the obstacle is a human body by comparing with the obtained capacitance value of the obstacle It is determined whether or not (step S107). If it is determined that the vehicle is a human body (Y in step S107), based on information from the vehicle speed sensor 90, for example, the vehicle 1 is in a predetermined traveling state as described above and the pedestrian protection airbags 81 to 83 are deployed. It is determined whether or not the condition is satisfied (step S108).

  If it is determined that the unfolding condition is satisfied (Y in step S108), a unfolding control signal is output to the pedestrian protection device 70, and walking at the corresponding position indicated by the unfolding control signal by the pedestrian protection device 70 is performed. The deployment control for deploying the person-protecting airbag is performed (step S109), and the series of deployment control processing according to this flowchart ends.

  Thus, the obstacle detection device for a vehicle detects an obstacle for the vehicle 1, and when the detected obstacle is a pedestrian (pedestrian's foot 49) and the vehicle 1 is in a predetermined running state, the pedestrian protection is performed. If the deployment of the airbags 81 to 83 is controlled, the pedestrian's foot 49 can be detected accurately and reliably, and the impact of the pedestrian on the hood 3 can be reduced even when the vehicle 1 collides.

  On the other hand, when it is determined that the obstacle is not close (N in Step S103) or when the comparison value is determined not to be equal to or greater than the predetermined threshold (N in Step S104), the obstacle is not detected. (Step S110), the deployment of the pedestrian protection airbags 81 to 83 is not performed, and the series of deployment control processing according to this flowchart is terminated.

  Further, when it is determined that the body is not a human body (N in Step S107), or when the vehicle 1 is not in a predetermined traveling state (for example, stopped), for example, and it is determined that the deployment condition is not satisfied (Step S107). N of S108 similarly ends the series of deployment control processes according to this flowchart without deploying the pedestrian protection airbags 81-83.

  Here, specifically, for example, in step S103, when the first capacitance value C1 is larger than the predetermined threshold value Th1, it is set so that it can be determined that the obstacle has approached the sensor electrode 11. Keep it. At this time, for example, in step S104, the comparison value α or the comparison value β calculated by a calculation formula such as the comparison value α = (a × C1) − (b × C2) or the comparison value β = d × C1 / C2. Is smaller than an arbitrary threshold value Th2 as a predetermined threshold value set in advance, it is set so that it can be determined that it is outside the detection range Z1 to Z3.

  Only when the obstacle is close (Y in step S104) and the comparison value is equal to or greater than the threshold Th2 (Y in step S105), the obstacle is determined to be detected (step S105). S106). Thus, according to the vehicle obstacle detection device of the present example, the detection ranges Z1 to Z1 on the surfaces of the capacitance sensor units 10 to 30 arranged on the front bumper 2 of the vehicle 1 (on the sensor electrode 11). The proximity of the obstacle (foot 49) into Z3 can be accurately and reliably detected.

  Note that the coefficients a, b, and c in the comparison values α and β, the calculation formulas of the comparison values α and β, the values of the threshold values Th1 and Th2, and the like may be as follows. That is, these change depending on factors such as the sensor shape of each of the capacitance sensor units 10 to 30, the environment around the installation, and the characteristics of the detection target. For this reason, what is necessary is just to set it sequentially, taking a profile, when these each factor is decided.

  In the above-described example, the proximity of the obstacle is determined by comparing using the value obtained by dividing the first capacitance value C1 by the second capacitance value C2. In addition, for example, the first capacitance value C1 is compared using a value obtained by dividing the first capacitance value C1 by the sum of the first capacitance value C1 and the second capacitance value C2, or other calculations are performed. You may make it determine proximity | contact using a method.

  Thus, according to the vehicle obstacle detection device of the present example, for example, when the threshold value Th2 is large, the directionality of the sensor sensitivity of each of the capacitance sensor units 10 to 30 is high, and when the threshold value Th2 is small, it is low. It can be. Therefore, it is possible to set the detection ranges Z1 to Z3 by arbitrarily adjusting the directivity on the surfaces of the respective capacitance sensor units 10 to 30 disposed on the front bumper 2, and to detect the desired directivity. Obstacles existing in the ranges Z1 to Z3 can be reliably and accurately detected with a simple configuration. Moreover, the detected obstacle and a pedestrian can be discriminate | determined using the acquired electrostatic capacitance value.

  Then, the pedestrian protection airbag deployment control device determines whether or not the detected obstacle is a human body, and when the detected obstacle is a human body and the vehicle 1 is in a predetermined running state, the pedestrian protection airbag. 81 to 83 can be developed. The CV conversion circuit 21 of the circuit unit 50 described above uses, for example, a known timer IC in which the duty ratio of the output pulse is changed by a resistor and a capacitor, but is not limited to this.

  That is, for example, a method in which a sine wave is applied to directly measure an impedance from a voltage change or a current value due to a capacitance value, a method in which an oscillation circuit is configured including a capacitance value to be measured, and an oscillation frequency is measured, RC A charge / discharge circuit is configured to measure the charge / discharge time, a charge charged with a known voltage is transferred to a known capacity and the voltage is measured, or an unknown capacity is charged with a known voltage and the charge is charged. There is a method to measure the number of times until the known capacity is charged to a predetermined voltage by moving it to a known capacity multiple times, setting a threshold value for the detected capacitance value, or a waveform of the capacitance May be processed as a trigger when the corresponding capacitance waveform is obtained.

  In addition, it is assumed that the CV conversion circuit 21 of the circuit unit 50 converts the capacitance into a voltage. However, it may be converted into data that can be handled electrically or as software, for example, the capacitance is converted into a pulse width. It may be converted or directly converted into a digital value.

  Further, in the vehicle obstacle detection device described above, the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13 of each of the capacitance sensor units 10 to 30 are disposed in the front bumper 2 of the vehicle 1. An example in which detection of an obstacle is determined by comparing the first capacitance value C1 of only the sensor electrode 11 with the second capacitance value C2 of the sensor electrode 11 and the auxiliary electrode 13 will be described. However, for example, the following may be used.

  FIG. 8 is an explanatory diagram illustrating another example of the overall configuration of the capacitance sensor unit and the circuit unit of the vehicle obstacle detection device. The vehicle obstacle detection device of this example has a configuration in which a dummy sensor electrode (dummy electrode) 19 is arranged in addition to the sensor electrode 11, and the CV conversion circuit 21 of the circuit unit 50 operates differentially. It is configured as.

  Specifically, as shown in FIG. 8, for example, the sensor electrode 11 is connected to the positive input end of the differential amplifier circuit, and the dummy electrode 19 is connected to the negative input end of the differential amplifier circuit. The value of the capacitance Cb is subtracted. The output value is compared with a threshold value by a comparator or the like to detect an obstacle.

  As an operation of such a CV conversion circuit 21, for example, when the switch S1 is open (OFF), the switch S2 is grounded (GND), and the switch S3 is closed (ON), the switch S3 is operated. Open (OFF), switch S2 is switched to Vr, and switch S1 is connected to the inverting input of the operational amplifier. Then, the capacitances Ca and Cf are charged with CaVr, and the capacitances Cb and Cf are charged with CbVr.

  Next, after the switch S1 is opened (OFF) and the switch S2 is grounded (GND), the output voltage V when the switch S1 is grounded (GND) is measured. The voltage at this time is V / Vr = {(Cf + Ca) / Cf} − {(Cf + Cb) / Cf}, and a voltage corresponding to the ratio between the capacitance Ca and the capacitance Cb is output.

  As described above, the CV conversion circuit 21 is configured to perform a differential operation (differential circuit), so that the temperature characteristics of the circuit can be offset and common mode noise can be reduced. At this time, for example, the dummy electrode 19 is connected to the negative input end of the differential amplifier circuit. However, if this dummy electrode 19 is capacitively coupled to the obstacle (foot 49), the sensitivity of the sensor itself is lowered.

  For this reason, the area of the dummy electrode 19 is made sufficiently small with respect to the sensor electrode 11, or another shield electrode 47 having the same potential is provided between the dummy electrode 19 and the obstacle (foot 49). It is necessary to reduce the capacitive coupling with the object (foot 49).

  In the shield drive circuit 24 described above, when the duty ratio changes according to the capacitance C, the output waveform of the sensor electrode 11 changes depending on the measured capacitance. To do. For this reason, a 1 × amplifier circuit may be configured with a voltage follower such as an operational amplifier or a source follower such as an FET, and the output of the sensor electrode 11 may be input and the output connected to the shield electrode 12 or the like. .

  Further, when the CV conversion circuit 21 operates differentially, the shield drive circuit 24 has a rectangular waveform with the voltage Vr and GND as the output waveform of the sensor electrode 11 and the frequency becomes the switching frequency of the switch. Therefore, since it does not vary depending on the capacitance value, the non-inverting input of the operational amplifier shown in FIG. 8 may be connected to the shield electrode 12 or the like. However, when a driving current is required, a rectangular wave of Vr and GND may be separately generated through an operational amplifier with a high output current.

  Furthermore, in the above-described embodiment, the sensor electrode 11 is connected to the CV conversion circuit 21, the shield electrode 12 is connected to the shield drive circuit 24, and the auxiliary electrode 13 is connected to the shield electrode 24 or C via the changeover switch SW. It was configured to be connected to the −V conversion circuit 21. In addition, for example, when the CV conversion circuit 21 operates differentially, the sensor electrode 11 is connected to the negative side input end shown in FIG. 8, the shield electrode 12 is connected to the shield drive circuit 24, and You may comprise so that the auxiliary electrode 13 may each be connected to a plus side input end.

  In this case, in the operation 2 described above, the auxiliary electrode 13 is connected to the sensor electrode 11 and there is almost no directivity. However, in the operation 1 described above, the value of the capacitive coupling between the auxiliary electrode 13 and the obstacle (foot 49) is subtracted from the capacitance value of the sensor electrode 11, and as a result has a loose directivity. It will be. Similar to the case described above, the same effect can be obtained by comparing the detection values in the operation 1 and the operation 2.

  Furthermore, in the above-described embodiment, the auxiliary switch 13 is configured to be connected to the shield drive circuit 24 during the operation 1 and connectable to the CV conversion circuit 21 during the operation 2 by the changeover switch SW. In the case of 1 and operation 2, the equal capacitance line (surface) M is made variable. In addition, the auxiliary electrode 13 is configured to be connected to the shield drive circuit 24 at the time of operation 1, for example, to be open, grounded, or connectable to a predetermined potential at the time of operation 2, or for example at the time of operation 1 Can be connected to an open, grounded or predetermined potential, and can be connected to the CV conversion circuit 21 in the operation 2 to obtain the same effect. In this way, the auxiliary electrode 13 is connected to the open state by the changeover switch SW, or connected to the ground or other potential (including a potential equivalent to the ground, pulse, charging voltage, sine wave, etc.). May be.

  Note that the change-over switch SW only needs to have a structure capable of switching electrical connection. For example, an electronic circuit switch such as an FET or a photo MOS relay or a mechanical switch such as a contact switch can be employed. In addition to the above-described shape, the sensor electrode 11 may have various shapes such as a circle, an ellipse, a rectangle, and a polygon. For example, the back side of the sensor electrode 11 is also in the detection range Z1 to Z3. In that case, the shield electrode 12 may not be installed.

  The auxiliary electrode 13 is arranged so as to surround the entire periphery of the sensor electrode 11. However, as long as the detection range Z1 to Z3 can be set, the auxiliary electrode 13 is in a state of surrounding a part or adjacent to the part. It may be arranged. Further, for example, when the sensor electrode 11 is surrounded, the sensor electrode 11 may be arranged concentrically (the center is the same).

  Next, a capacitance sensor unit and a circuit unit of a vehicle obstacle detection device according to another embodiment of the present invention will be described with reference to FIGS. In the vehicle obstacle detection device according to the above-described embodiment, the output from the CV conversion circuit 21 of the circuit unit 50 is the second static value indicating the capacitance detected by the sensor electrode 11 and the auxiliary electrode 13. Either the capacitance value C2 or the first capacitance value C1 indicating the capacitance detected only by the sensor electrode 11 is obtained.

  For this reason, the capacitance value detected by the structure around the installation place of the sensor electrode 11 (including the capacitance sensor units 10 to 30) may differ. In such a case, the comparison result obtained by comparing the first and second capacitance values C1 and C2 may change depending on the structure around the place where the sensor electrode 11 is installed. In order to avoid such a situation, the internal configuration of the circuit unit 50 may be further set as follows, for example.

  FIG. 9 is an explanatory diagram showing an example of the overall configuration of each of the capacitance sensor units 10 to 30 and the circuit unit 50 of the vehicle obstacle detection device according to another embodiment of the present invention, and FIG. The flowchart which shows the example of the expansion control processing procedure of the airbags 81-83 for pedestrian protection by the airbag expansion | deployment control apparatus for pedestrian protection provided with the object detection apparatus, FIG. 11 is each electrostatic of the obstacle detection apparatus for vehicles It is explanatory drawing which shows the other example of the whole structure of the capacitance sensor parts 10-30 and the circuit part 50. FIG. In the following description, parts that are the same as those already described are denoted by the same reference numerals, description thereof is omitted, and parts not particularly related to the present invention may not be specified.

  As shown in FIG. 9, in the circuit unit 50 of this example, in addition to the CV conversion circuit 21 and the shield drive circuit 24 described above, a determination circuit 25 made of, for example, a CPU and an obstacle (foot 49) approach each other. An initial capacity storage device 26 that stores an electrostatic capacitance value (initial capacity) when not being switched, a switch control circuit 27 that controls the switching operation of the selector switch SW, and a buffer 28 are configured.

  As an outline of the detection operation of the detection target (foot 49) of the vehicle obstacle detection device having the circuit unit 50 configured as described above, for example, each of the capacitance sensor units 10 to 30 is similarly used as the front bumper of the vehicle 1. Place in 2. Thereafter, the capacitance value (initial capacitance) in the operation 1 and the operation 2 when the obstacle is not approaching each of the capacitance sensor units 10 to 30 is switched by the switch control circuit 27 under the control of the switch SW. Detect each.

  Then, these values are stored in the initial capacity storage device 26, and the initial capacity is determined from the first and second electrostatic capacitance values C1 and C2 in the actual operations 1 and 2 described above in the determination circuit 25. These initial capacities stored in the storage device 26 are subtracted and compared. Based on the comparison result thus obtained, it is determined whether or not the obstacle (foot 49) is within the detection range Z1 to Z3 on the sensor electrode 11.

  More specifically, the initial capacity is stored as the first initial capacity when the changeover switch SW is connected to the shield drive circuit 24 side by the control of the switch control circuit 27 as the first initial capacity. It is stored in the device 26. In addition, the operation at the time of the operation 2 when the changeover switch SW is connected to the CV conversion circuit 21 side is stored in the initial capacity storage device 26 as the second initial capacity.

  Then, in the actual operation 1, the determination circuit 25 subtracts the first initial capacity stored in the initial capacity storage device 26 from the detected first capacitance value C1 and performs the first detection. Value (detection value 1). In the actual operation 2, the second detection value (detection value 2) is obtained by subtracting the second initial capacitance stored in the initial capacitance storage device 26 from the detected second capacitance value C2. ).

  That is, as shown in FIG. 10, first, the vehicle obstacle detection device starts processing of the vehicle obstacle detection device, for example, triggered by the ignition switch of the vehicle 1 being turned on as an accessory or ON. Then, the first detection value and the second detection value as described above are calculated (step S201), and these are compared to calculate a comparison value (step S202).

  Thereafter, based on the first or second detection value, it is determined whether or not the detection target (obstacle) is close (step S203). At the same time, whether the comparison value of the first detection value and the second detection value is, for example, a predetermined threshold value or more (or less than a predetermined threshold value or less than a predetermined threshold value). It is determined whether or not (step S204).

  That is, here, it is determined whether there is an obstacle in the detection ranges Z1 to Z3 based on the detection values 1 and 2 and the comparison result. In addition, the detection value 2 at the time of the said operation | movement 2 with which the sensor electrode 11 and the auxiliary electrode 13 are connected to the CV conversion circuit 21 is a detection value in the state where there is no directivity in sensor sensitivity, The output depends on the approach to each capacitance sensor unit 10-30.

  When it is determined that an obstacle is close (Y in step S203) and the comparison value is determined to be equal to or greater than a predetermined threshold (Y in step S204), the obstacle is determined to be detected. (Step S205), information related to the detection result including the determination result is output to the control unit 60.

  The control unit 60 of the pedestrian protection airbag deployment control device determines which of the capacitance sensor units 10 to 30 detects the obstacle based on the information about the detection result. Then, the position of the obstacle is specified (step S206).

  Then, once the position of the obstacle is identified, for example, referring to the profile data of the capacitance value stored in advance, whether the obstacle is a human body by comparing with the obtained capacitance value of the obstacle It is determined whether or not (step S207). If it is determined that the vehicle is a human body (Y in step S207), for example, the vehicle 1 is in a predetermined traveling state as described above based on the information from the vehicle speed sensor 90, and the pedestrian protection airbags 81-83 are deployed. It is determined whether or not the condition is satisfied (step S208).

  If it is determined that the unfolding condition is satisfied (Y in step S208), the unfolding control signal is output to the pedestrian protection device 70, and the walking at the corresponding position instructed by the unfolding control signal by the pedestrian protection device 70. The deployment control for deploying the person protecting airbag is performed (step S209), and the series of deployment control processing according to this flowchart is terminated.

  On the other hand, when it is determined that the obstacle is not close (N in step S203), or when it is determined that the comparison value is not equal to or greater than the predetermined threshold (N in step S204), the obstacle is not detected. (Step S210), the deployment of the pedestrian protection airbags 81 to 83 is not performed, and the series of deployment control processing according to this flowchart is terminated.

  Further, when it is determined that the vehicle is not a human body (N in step S207), or when the vehicle 1 is not in a predetermined traveling state (for example, stopped), for example, and it is determined that the deployment condition is not satisfied (step) N of S208 similarly ends the series of deployment control processing according to this flowchart without deploying the pedestrian protection airbags 81-83.

  Although it is determined that the obstacle is close (Y in step S203), if it is determined that the comparison value is not equal to or greater than the predetermined threshold (N in step S204), the obstacle is not detected. Determination is made (step S210). Then, for example, a non-detection signal A (for example, a high impedance, a predetermined potential, etc.) that is a disable signal indicating that no obstacle is present in the detection ranges Z1 to Z3 when directivity is given is determined and output. Output as.

  Further, for example, based on the first or second detection value (or the first or second capacitance value C1, C2), it is determined whether or not the obstacle is close (step S203). When it is determined that they are not close to each other (N in step S203), the process proceeds to step S210 and it is determined that these are not detected. Then, for example, a non-detection signal B (a signal different from the non-detection signal A) that is a disable signal indicating that an obstacle is not within the detection ranges Z1 to Z3 on the sensor electrode 11 is output as a determination output.

  In this way, by using the output of the determination circuit 25 as an enable signal or a disable signal, for example, according to the determination result, the enable signal is input to the buffer 28 when the obstacle is within the detection range Z1 to Z3 on the sensor electrode 11. The detection value 1 is output from the buffer 28. When the obstacle is not within the detection range Z1 to Z3 on the sensor electrode 11, the determination output is fixed to a predetermined voltage such as a ground voltage or a reference voltage as a disable signal, or becomes a high impedance output.

  When the obstacle is in the detection range Z1 to Z3 on the sensor electrode 11, in addition to the detection value 1, the detection value 2 and the first or second capacitance values C1 and C2 are output. Also good. The detection value 1, the detection value 2, and the first and second capacitance values C1 and C2 indicate values according to the distance of the obstacle to the sensor electrode 11, for example.

  Thus, according to the circuit unit 50 configured as described above, when the obstacle (foot 49) is within the detection range Z1 to Z3, a detection value corresponding to the distance is output and is not within the detection range Z1 to Z3. When the output is a predetermined voltage or the like. Therefore, it is possible to determine whether or not there is an obstacle (foot 49) in the detection range Z1 to Z3, and if so, how long it is. That is, it is possible to increase the intensity of directivity of the sensor sensitivity of each of the capacitance sensor units 10 to 30 or to set the directivity in more detail.

  Further, as another example of a method for avoiding the dependence on the structure around the place where each of the capacitance sensor units 10 to 30 is installed, these are maintained by adjusting the reference voltage as follows. It is also possible. That is, as shown in FIG. 11, the circuit unit 50 in this example includes a reference voltage adjustment circuit 40 and a subtraction circuit 31 in addition to the CV conversion circuit 21 and the shield drive circuit 24.

  The reference voltage adjustment circuit 40 adjusts the output of the CV conversion circuit 21 to the reference potential when measuring the initial capacitances of the first and second initial capacitances as described above. Here, the reference voltage adjustment circuit 40 includes a comparator 41, a control circuit 42, a register 43, a D / A converter 44, and an adjustment unit 45.

  For example, the reference voltage adjustment circuit 40 inputs the output of the CV conversion circuit 21 from the positive input terminal of the comparator 41 and inputs the reference voltage (Reference Voltage: RV) from the negative input terminal, and compares the two. Then, the set value of the register 43 is changed under the control of the control circuit 42 based on the comparison result.

  Further, after the output of the register 43 is converted from a digital signal to an analog signal by the D / A converter 44, the voltage is adjusted by the adjusting unit 45, and the output from the adjusting unit 45 is used to adjust the voltage of the CV conversion circuit 21. Adjust the input. In this way, in the operation 1 when the obstacle is not close to each of the capacitance sensor units 10 to 30, the setting of the register 43 is performed when the output from the CV conversion circuit 21 is closest to the reference potential. The value is fixed and the output of the first initial capacity is used as the reference voltage, and the set value (set value 1) at that time is stored.

  At the same time, in the operation 2 when the obstacle is not close to each of the capacitance sensor units 10 to 30, the set value of the register 43 is set when the output from the CV conversion circuit 21 is closest to the reference potential. The second initial capacitance output is fixed as the reference potential, and the set value (set value 2) at that time is stored.

  In the actual operation 1, the output of the CV conversion circuit 21 when the set value 1 of the register 43 is fixed is input to, for example, the plus side input terminal of the subtraction circuit 31, and the reference voltage RV is minus. The value is input to the side input terminal, and the output is subtracted by the reference voltage RV to obtain the detected value 1. Further, in the actual operation 2, the output of the CV conversion circuit 21 when the register 43 is fixed to the set value 2 is input to, for example, the plus side input terminal of the subtraction circuit 31, and the reference voltage RV is minus. The value is input to the side input terminal, and the output is subtracted by the reference voltage RV to obtain the detection value 2.

  Then, by comparing these detection value 1 and detection value 2, whether or not there is an obstacle (foot 49) in the detection range Z1 to Z3 on the sensor electrode 11 in the same manner, and if so, what distance Is determined. The input to the CV conversion circuit 21 is adjusted by, for example, increasing or decreasing the input capacitance by applying the voltage of the D / A converter 44 to the adjustment unit 45 including a fixed capacitor connected to the input. Can be realized.

  FIG. 12 is an explanatory diagram showing an example of the overall configuration of the capacitance sensor unit and the circuit unit of the obstacle detection device for a vehicle according to still another embodiment of the present invention, and FIG. 13 is an illustration of the obstacle detection device for the vehicle. FIG. 14 to FIG. 16 are diagrams for explaining an operation concept during the detection operation, and FIGS. 14 to 16 illustrate the relationship between the detection object and the lines of electric force during the first detection operation (operation 3) of the obstacle detection device for the vehicle. It is explanatory drawing for doing.

  FIGS. 17 to 19 are explanatory diagrams for explaining the relationship between the detection target object and the lines of electric force during the second detection operation (operation 4) of the vehicle obstacle detection device. It should be noted that a description overlapping the part already described in the above-described embodiment may be omitted.

  As illustrated in FIG. 12, the vehicle obstacle detection device according to the present embodiment has the same configuration as the vehicle obstacle detection device according to the above-described embodiment, and each of the capacitance sensor units 10 to 30. The circuit unit 50 is provided. Each of the capacitance sensor units 10 to 30 includes a sensor electrode 11, a shield electrode 12, and an auxiliary electrode 13 </ b> A formed in a hollow long frame shape surrounding the sensor electrode 11 like the auxiliary electrode 13. It is configured.

  The sensor electrode 11 is provided mainly for detecting an obstacle (foot 49) existing in the detection ranges Z1 to Z3 of the detection area on the detection surface side. The shield electrode 12 has the above-described action. The auxiliary electrode 13 </ b> A is provided mainly to vary the equal capacitance line (surface) on the equal electrostatic side on the detection surface side of the sensor electrode 11.

  The circuit unit 50 is directly connected to the CV conversion circuit 21 connected to the sensor electrode 11 or the auxiliary electrode 13A, the A / D converter 22, the CPU 23, and the shield electrode 12, and the sensor electrode 11 or the auxiliary electrode. And a shield drive circuit 24 connected to 13A.

  The circuit unit 50 also includes a first changeover switch SW1 that switches the input from the sensor electrode 11 to the CV conversion circuit 21 or the shield drive circuit 24, and the input from the auxiliary electrode 13A to the shield drive circuit 24 or the CV conversion. A second changeover switch SW2 for switching to the circuit 21 is provided. The first and second changeover switches SW1 and SW2 are configured to be switchable to the A side and the B side (see FIG. 12 and the like), respectively.

  The CV conversion circuit 21 converts the capacitance detected by the sensor electrode 11 or the auxiliary electrode 13A into a voltage. The A / D converter 22 operates in the same manner as described above. The CPU 23 controls the entire vehicle obstacle detection device and controls the operation of the alternate connection (an alternative connection to the A side or the B side) of the first and second changeover switches SW1 and SW2, for example. Or the detection of the detection object (foot 49) in the detection region (proximity or presence of the foot 49) is determined. The shield drive circuit 24 drives the shield electrode 12 and the auxiliary electrode 13A or the sensor electrode 11 to, for example, the same potential as the sensor electrode 11.

  Since the structures and configurations of the capacitance sensor units 10 to 30 and the circuit unit 50 and the structures and configurations of the electrodes 11 to 13A are the same as those already described in the above-described embodiment, they will be described here. Is omitted. Note that the first changeover switch SW1 is configured such that, for example, when the sensor electrode 11 is not connected to the CV conversion circuit 21, the sensor electrode 11 can be opened, grounded, or connected to a predetermined potential. The second changeover switch SW2 May be configured such that when the sensor electrode 11 is connected to the CV conversion circuit 21, the auxiliary electrode 13A can be opened, grounded, or connected to a predetermined potential.

  The shield drive circuit 24 is configured to give the auxiliary electrode 13A a potential equivalent to that of the sensor electrode 11, or to give the sensor electrode 11 a potential equivalent to that of the auxiliary electrode 13A. The first changeover switch SW1 is configured so that the sensor electrode 11 can be connected to the shield drive circuit 24 when the sensor electrode 11 is not connected to the CV conversion circuit 21, and the second changeover switch SW2 is configured so that the sensor electrode 11 is connected to the shield drive circuit 24. The auxiliary electrode 13 </ b> A may be configured to be connectable to the shield drive circuit 24 when connected to the CV conversion circuit 21.

  Further, the shield drive circuit 24 may be configured to apply a potential equivalent to that of the sensor electrode 11 to the auxiliary electrode 13A. In this case, the first changeover switch SW1 has the sensor electrode 11 connected to the CV conversion circuit 21. The auxiliary electrode 13A may be open, grounded, or connectable to a predetermined potential when not connected. The second changeover switch SW2 may be configured to connect the auxiliary electrode 13A to the shield drive circuit 24 when the sensor electrode 11 is connected to the CV conversion circuit 21.

  The shield drive circuit 24 is configured to give the sensor electrode 11 the same potential as the auxiliary electrode 13A. In this case, the first changeover switch SW1 is not connected to the CV conversion circuit 21. Sometimes, the auxiliary electrode 13A may be configured to be connectable to the shield drive circuit 24. The second changeover switch SW2 may be configured so that the auxiliary electrode 13A can be opened, grounded, or connected to a predetermined potential when the sensor electrode 11 is connected to the CV conversion circuit 21.

  Next, the detection operation of the detection target (foot 49) of the vehicle obstacle detection device configured as described above will be described. First, under the control of the CPU 23, both the first and second changeover switches SW 1 and SW 2 are switched to the A side, and the sensor electrode 11 is connected to the CV conversion circuit 21. In addition, an operation (operation 3) when the shield electrode 12 and the auxiliary electrode 13A are connected to the shield drive circuit 24 will be described.

  In the case of the operation 3, the connection state of the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13A with the circuit unit 20 is as shown in FIG. That is, as described above, only the sensor electrode 11 is connected to the CV conversion circuit 21, and the shield electrode 12 and the auxiliary electrode 13 </ b> A are connected to the shield drive circuit 24. Thereby, the electrostatic capacitance C with the detection objects X, Y, W is detected by the CV conversion circuit 21 only by the sensor electrode 11.

  In addition, the back side of the sensor electrode 11 of each of the capacitance sensor units 10 to 30 is in a state covered with the shield electrode 12. For this reason, the sensor sensitivity on the back surface side of the sensor electrode 11 is considerably lower than that on the detection surface side because only the electric lines of force that wrap around from the detection surface (front surface) of the sensor electrode 11 are detected. Here, the detection target object X is described as a detection target object existing in the detection ranges Z1 to Z3, and the detection target objects Y and W are described as detection target objects existing outside the detection ranges Z1 to Z3.

  As shown in FIG. 14, the electric lines of force P1 from the sensor electrode 11 to the detection target X are less affected by the electric lines of force P2 (shield) from the auxiliary electrode 13A.

  On the other hand, as shown in FIG. 15, the electric lines of force P1 from the sensor electrode 11 with respect to the detection target Y at a distance substantially equal to the detection target X are affected by the electric lines of force P2 (shield) from the auxiliary electrode 13A. In response to this, it decreases compared to the case of the detection object X. For this reason, the detection target Y is weaker in capacitive coupling with the sensor electrode 11 than the detection target X.

  Thereby, it becomes possible to easily identify the detection objects X and Y in the operation 3 (that is, whether the detection objects are within the detection ranges Z1 to Z3 or outside the detection ranges Z1 to Z3). However, as shown in FIG. 16, in the detection target W closer to the sensor electrode 11 than the detection target Y, the electric lines of force P1 from the sensor electrode 11 are the same as those for the detection target X in FIG. , The output from the CV conversion circuit 21 is the same.

  That is, the detection target object X and the detection target object W are on the equipotential surface (line) M in FIG. 13, and the detection value (capacitance value) in the operation 3 is the same. For this reason, it is difficult to identify whether the detection object W exists in the detection ranges Z1 to Z3 or outside the detection ranges Z1 to Z3 only by the operation 3. In this embodiment as well, as in the above-described embodiment, the determination is not made only by the operation 3, but the electrostatic capacitance as the first capacitance value detected by the CV conversion circuit 21 at the time of the operation 3 is determined. The capacitance value C1 is stored in the storage means by the CPU 23.

  Next, under the control of the CPU 23, both the first and second changeover switches SW 1 and SW 2 are switched to the B side, and the auxiliary electrode 13 A is connected to the CV conversion circuit 21. In addition, an operation (operation 4) when the shield electrode 12 and the sensor electrode 11 are connected to the shield drive circuit 24 will be described.

  In addition, the structure corresponding to FIG. 13 which shows the connection state with the circuit part 50 of the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13A in the obstacle detection apparatus for vehicles in the case of operation | movement 4 is each changeover switch SW1 in FIG. , SW2 is switched to the B side. For this reason, illustration and description are omitted here.

  In this operation 4, only the auxiliary electrode 13 </ b> A is connected to the CV conversion circuit 21, and the shield electrode 12 and the sensor electrode 11 are connected to the shield drive circuit 24. Thereby, the capacitance C with the detection objects X, Y, W is detected by the CV conversion circuit 21 only by the auxiliary electrode 13A. Various conditions such as the arrangement positions of the detection objects X, Y, and W with respect to the capacitance sensor units 10 to 30 are the same as those in the operation 3.

  In the case of this operation 4, as shown in FIG. 17, the electric force line P2 (shield) from the sensor electrode 11 with respect to the detection target X has a great influence on the electric force line P1 from the auxiliary electrode 13A. For this reason, the detection object X has weak capacitance coupling with the auxiliary electrode 13A, and the capacitance value detected by the CV conversion circuit 21 is compared with the detection object X in the operation 3. Become smaller.

  On the other hand, as shown in FIG. 18, the electric force line P2 (shield) from the sensor electrode 11 with respect to the detection target Y is reduced as compared with the case with respect to the detection target X, and the electric force line P1 from the auxiliary electrode 13A. Increases compared to the case of the detection object X. For this reason, in the case of the operation 4, the detection target Y has a strong capacitive coupling with the auxiliary electrode 13A, and the capacitance value detected by the CV conversion circuit 21 is the detection target in the operation 3. Compared to the case for the object Y, it becomes larger.

  Further, as shown in FIG. 19, the electric lines of force P1 from the auxiliary electrode 13A to the detection object W are larger than the electric lines of force P1 from the auxiliary electrode 13A to the detection object X in FIG. The influence of the electric lines of force P2 (shield) from the electrode 11 is also small. For this reason, in the operation 4, the output from the CV conversion circuit 21 in the detection target W is larger than that in the detection target X. Then, the capacitance value C2 as the second capacitance value detected by the CV conversion circuit 21 during the operation 4 is stored in the storage means by the CPU 23.

  If the first and second capacitance values C1 and C2 are detected in this way, the CPU 23 compares these capacitance values C1 and C2 stored in the storage means. For example, in the detection object X described above, the first capacitance value C1 in the operation 3 is larger than the second capacitance value C2 in the operation 4, but in the detection object Y, the operation The first capacitance value C1 at 3 is smaller than the second capacitance value C2 at operation 4. For this reason, in the detection target W, the first capacitance value C1 in the operation 3 and the second capacitance value C2 in the operation 4 are approximately the same.

  As described above, the CPU 23 determines how far the detection target exists from the center of the sensor electrode 11 by comparing the value of the capacitance value C2 with the capacitance value C1. Is possible. At this time, if the comparison value of the capacitance values C1 and C2 is, for example, a predetermined threshold value or more (or less than a predetermined threshold value or less than a predetermined threshold value), the sensor electrode 11 If it is set so that it can be determined that it is within the upper detection ranges Z1 to Z3, directivity can be arbitrarily given.

  In the explanatory diagrams shown in FIGS. 13 to 19, the detection value in the operation 3 is larger than the detection value in the operation 4 for the detection target X, and the detection value in the operation 3 is the detection value in the operation 3 for the detection target Y. Smaller than the detected value. In the detection target W, the detection value in the operation 3 and the detection value in the operation 4 are described as examples. However, when various conditions such as the arrangement shape and the arrangement area of the sensor electrode 11 and the auxiliary electrode 13A change, the vertical relationship between the operation 3 and the operation 4 on the detection objects X, Y, and W changes.

  However, the ratio (C2 / C1) of the second capacitance value C2 in the operation 4 to the first capacitance value C1 in the operation 3 is always the detection object X <the detection object Y (or the detection object W). ) So that it can be distinguished. Therefore, if the comparison formula between the operation 3 and the operation 4 is changed for each condition, the detection objects X, Y, and W can be determined. Note that the comparison formulas, comparison values, various coefficients, predetermined threshold values (Th1, Th2), and the like are the same as those described in the above-described embodiment, and thus description thereof is omitted here.

  In addition, although there are cases where it cannot be expressed by a mathematical expression depending on conditions, the values of the capacitance values C1 and C2 at the positions within the detection range Z1 to Z3 of the detection target (foot 49) are measured and profiled in advance. What is necessary is just to compare each profile with an actual detection value.

  As described above, according to the vehicle obstacle detection device, for example, when the predetermined threshold Th2 is large, the directionality of the sensor sensitivity of each of the capacitance sensor units 10 to 30 is high. The intensity of directivity can be low. Thereby, the directivity of the sensor sensitivity can be arbitrarily set, and the detection ranges Z1 to Z3 on the sensor electrode 11 can be arbitrarily determined, and the detection targets in the detection ranges Z1 to Z3 having the desired directivity are obtained. The proximity of the object (foot 49) can be reliably and accurately detected with a simple configuration.

  Based on the determination result, the control unit 60 of the airbag deployment control device for protecting pedestrians, for example, detects the foot 49, and if the vehicle 1 is in a predetermined running state, A deployment control signal for controlling deployment of the pedestrian protection airbags 81 to 83 at the arrangement position corresponding to the capacitance sensor unit is output to the pedestrian protection device 70. In this way, the pedestrian's foot 49 can be detected in front of the front bumper 2 of the vehicle 1 prior to the actual collision, and based on this, the pedestrian protection airbags 81 to 83 can be deployed. For example, the impact of the pedestrian on the bonnet 3 can be reduced.

  Note that the various configurations and operations of the CV conversion circuit 21 of the circuit unit 50 are the same as those described in the above-described embodiment, and thus description thereof is omitted here. In the vehicle obstacle detection device according to the present embodiment, the sensor electrode 11, the shield electrode 12, and the auxiliary electrode 13A are arranged, and the electrostatic capacitance value C1 of the sensor electrode 11 and the electrostatic capacitance value of the auxiliary electrode 13A. A description has been given of an example in which the detection of the detection target (foot 49) is determined by comparing with C2. In addition, as described with reference to FIG. 8 in the above-described embodiment, the dummy electrode 19 may be disposed and the CV conversion circuit 21 may be configured to perform a differential operation. Since the various configurations and operations are the same as those described above, the description thereof is omitted here.

  Further, since the various configurations and operations of the modified example of the shield drive circuit 24 and the modified examples of the first and second changeover switches SW1 and SW2 are the same as those described in the above-described embodiment, Description is omitted.

  In the vehicle obstacle detection device according to the present embodiment, the auxiliary electrode 13A is disposed so as to surround the entire periphery of the sensor electrode 11. Therefore, each of the capacitance sensor units 10 to 30 has the same directivity in all directions of the detection surface of the sensor electrode 11 (that is, the detection ranges Z1 to Z3 are the same in any direction with respect to the sensor electrode 11). If there is a direction in which it is not desired to have sex, for example, the following may be performed.

  That is, the auxiliary electrode 13A is not disposed in a direction in which directivity is not desired, and the auxiliary electrode 13A is formed in a U shape, a C shape, an L shape, a semicircle, or the like, for example. It is also possible to reduce the directivity in the direction where there is no noise.

  Further, since the output from the CV conversion circuit 21 of the circuit unit 50 described above is either the first capacitance value C1 or the second capacitance value C2, each sensor electrode 11 (including each of the sensor electrodes 11) is included. The capacitance value detected may vary depending on the structure around the installation location of the capacitance sensor units 10 to 30).

  Then, the comparison result obtained by comparing the first and second capacitance values C1 and C2 may change depending on the structure around the place where the sensor electrode 11 is installed. In order to avoid such a situation, the configuration of the circuit unit 50 may be further configured as follows, for example.

  FIG. 20 is an explanatory diagram showing an example of the overall configuration of the capacitance sensor unit and the circuit unit of the vehicle obstacle detection device according to still another embodiment of the present invention, and FIG. 21 is a diagram of the vehicle obstacle detection device. It is explanatory drawing which shows the other example of the whole structure of an electrostatic capacitance sensor part and a circuit part. Note that, in the above-described embodiment, the same reference numerals are given to portions overlapping with the already described portions, and the description is omitted.

  As shown in FIG. 20, the circuit unit 50 includes a CV conversion circuit 21, a shield drive circuit 24, a determination circuit 25, an initial capacity storage device 26 that stores the above-described initial capacity, and a switching operation of each switch SW1 and SW2. A switch control circuit 27 for controlling the signal and a buffer 28.

  As an outline of the detection operation of the detection target (foot 49) of the vehicle obstacle detection device having such a circuit unit 50, for example, after each capacitance sensor unit 10-30 is installed at a predetermined installation location, Capacitance values (initial capacities) when the detection object (foot 49) is not approaching each of the capacitance sensor units 10 to 30 are controlled by the switch control circuit 27 so that the switches SW1 and SW2 are switched. These values are detected and stored in the initial capacity storage device 26.

  Then, the initial capacitance stored in the initial capacity storage device 26 is subtracted from the first and second capacitance values C1 and C2 in the actual operation 3 and 4 described above in the determination circuit 25 and compared. Based on the comparison result, it is determined whether or not the detection target (foot 49) is within the detection range Z1 to Z3 on the sensor electrode 11.

  Specifically, the initial capacity is set as the first initial capacity at the time of the above operation 3 when the respective switches SW1 and SW2 are connected to the A side under the control of the switch control circuit 27. The switch at the time of the above operation 4 when the switches SW1 and SW2 are connected to the B side is stored in the initial capacity storage device 26 as the second initial capacity.

  In the actual operation 3, the determination circuit 25 subtracts the first initial capacitance stored in the initial capacitance storage device 26 from the detected first capacitance value C1 and performs the first detection. A value (detection value 1), and in the case of operation 4, the second detection value is obtained by subtracting the second initial capacitance stored in the initial capacitance storage device 26 from the detected second capacitance value C2. (Detection value 2).

  Thereafter, the determination circuit 25 compares the detection value 1 and the detection value 2 and determines whether or not there is a detection target (foot 49) within the detection range Z1 to Z3 based on the comparison result. For example, the detection value 1 at the time of the operation 3 is an output depending on the approach of the detection target (foot 49) to each of the capacitance sensor units 10 to 30. Since subsequent operations, functions, effects, and the like are the same as those described in the above-described embodiment, description thereof is omitted here.

  The first and second initial capacitances described above may be, for example, digitally converted from the voltage at the time of initial capacitance measurement by an A / D converter or the like and held in a register or a memory. Thus, it is possible to hold these by adjusting the reference voltage. That is, as shown in FIG. 21, the circuit unit 50 includes a CV conversion circuit 21, a shield drive circuit 24, a reference voltage adjustment circuit 40, and a subtraction circuit 31.

  The reference voltage adjustment circuit 40 is for adjusting the output of the CV conversion circuit 21 to the reference potential at the time of initial capacitance measurement of the first and second initial capacitances as described above. , A comparator 41, a control circuit 42, a register 43, a D / A converter 44, and an adjustment unit 45. Since these configurations, operations, and the like are also the same as those described in the above-described embodiment, description thereof is omitted here.

  The output of the first and second initial capacitors is set as a reference voltage by the reference voltage adjustment circuit 40, and the output of the CV conversion circuit 21 thus set to the reference voltage is applied to, for example, the positive side input terminal of the subtraction circuit 31. The reference voltage RV is input to the negative input terminal, the output is subtracted by the reference voltage RV, and the first and second initial capacities are subtracted. Similarly, the detection object (foot) 49) It can be determined whether or not there is, and if so, how long it is.

  As described above, according to the vehicle obstacle detection device according to the above-described embodiment, the detection ranges Z1 to Z1 having desired directivity on the sensor electrode 11 by the capacitance sensor units 10 to 30. It can be determined whether there is an obstacle in Z3. Based on the determination result, the obstacle is a human body. For example, when the foot 49 is detected, the corresponding pedestrian protection airbags 81 to 83 can be deployed. In this way, it is possible to reduce the impact of a pedestrian crashing into the hood 3.

  In the vehicle obstacle detection device according to the above-described embodiment, the capacitance sensor units 10 to 30 are arranged on the front bumper 2 of the vehicle 1. For example, the pedestrian protection airbags 81 to 83 are used. May be arranged on the rear bumper when it is arranged on the rear trunk lid or the rear gate. In this case, the predetermined traveling state may be that the vehicle 1 is moving backward at a predetermined speed.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Front bumper 3 Bonnet 10 1st electrostatic capacitance sensor part 11 Sensor electrode 12 Shield electrode 13 Auxiliary electrode 13A Auxiliary electrode 19 Dummy electrode 20 2nd electrostatic capacitance sensor part 21 CV conversion circuit 22 A / D converter 23 CPU
24 Shield Drive Circuit 25 Judgment Circuit 26 Initial Capacity Storage Device 27 Switch Control Circuit 28 Buffer 30 Third Capacitance Sensor Unit 31 Subtraction Circuit 40 Reference Voltage Adjustment Circuit 41 Comparator 42 Control Circuit 43 Register 44 D / A Converter 45 Adjustment Unit 49 foot 50 circuit unit 60 control unit 70 pedestrian protection device 81 first pedestrian protection airbag 82 second pedestrian protection airbag 83 third pedestrian protection airbag 90 vehicle speed sensor

Claims (14)

A plurality of capacitance sensor units arranged so that a detection surface exists in front of the vehicle bumper;
The capacitance sensor unit is
A sensor electrode;
An auxiliary electrode provided in the vicinity of the sensor electrode,
A detection circuit connected to at least the sensor electrode and detecting a capacitance value based on a capacitance from the connected electrode;
A changeover switch capable of selectively switching between a first connection state in which the auxiliary electrode is not connected to the detection circuit and a second connection state in which the auxiliary electrode is connected to the detection circuit;
A comparison value comparing a first capacitance value from the detection circuit in the first connection state with a second capacitance value from the detection circuit in the second connection state; and the first A vehicle obstacle detection device comprising: a determination unit that determines whether an obstacle is within a detection range on the sensor electrode based on the first or second capacitance value. 2. The vehicle obstacle detection device according to claim 1, wherein the change-over switch is configured to be able to open, connect to a ground, or a predetermined potential when the auxiliary electrode is in the first connection state. . A shield driving circuit for applying a potential equal to that of the sensor electrode to the auxiliary electrode;
The vehicle obstacle detection device according to claim 1, wherein the change-over switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state. A plurality of capacitance sensor units arranged so that a detection surface exists in front of the vehicle bumper;
The capacitance sensor unit is
A sensor electrode;
An auxiliary electrode provided in the vicinity of the sensor electrode,
A detection circuit for detecting a capacitance value based on a capacitance from the sensor electrode;
A shield drive circuit for applying a potential equal to that of the sensor electrode to the auxiliary electrode;
A changeover switch capable of selectively switching between a first connection state in which the auxiliary electrode is connected to the shield drive circuit and a second connection state in which the auxiliary electrode is opened, grounded or connected to a predetermined potential;
A comparison value comparing a first capacitance value from the detection circuit in the first connection state with a second capacitance value from the detection circuit in the second connection state; and the first A vehicle obstacle detection device comprising: a determination unit that determines whether an obstacle is within a detection range on the sensor electrode based on the first or second capacitance value. A plurality of capacitance sensor units arranged so that a detection surface exists in front of the vehicle bumper;
The capacitance sensor unit is
A sensor electrode;
An auxiliary electrode provided in the vicinity of the sensor electrode,
A detection circuit for detecting a capacitance value based on the capacitance from the connected electrodes;
A first changeover switch capable of selectively switching between a first connection state in which the sensor electrode is connected to the detection circuit and a second connection state in which the sensor electrode is not connected to the detection circuit;
When the sensor electrode is in the first connection state, the auxiliary electrode is not connected to the detection circuit, and when the first changeover switch is in the second connection state, the auxiliary electrode is connected to the detection circuit. A switchable second changeover switch,
A comparison value comparing the first capacitance value from the detection circuit in the case of the first connection state and the second capacitance value from the detection circuit in the case of the second connection state. And a determination means for determining whether or not the obstacle is within a detection range on the sensor electrode based on the first or second capacitance value. Detection device. The first changeover switch is configured to be able to open the sensor electrode, connect to ground or a predetermined potential in the second connection state,
The vehicle obstacle detection according to claim 5, wherein the second changeover switch is configured to be able to open, ground, or connect the auxiliary electrode to a predetermined potential in the first connection state. apparatus. A shield driving circuit for giving the auxiliary electrode the same potential as the sensor electrode, or giving the sensor electrode the same potential as the auxiliary electrode,
The first changeover switch is configured to connect the sensor electrode to the shield drive circuit in the second connection state,
The vehicle obstacle detection device according to claim 5, wherein the second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state. A shield driving circuit for applying a potential equal to that of the sensor electrode to the auxiliary electrode;
The first changeover switch is configured to be able to open the auxiliary electrode in the second connection state, connect to ground or a predetermined potential,
The vehicle obstacle detection device according to claim 5, wherein the second changeover switch is configured to be able to connect the auxiliary electrode to the shield drive circuit in the first connection state. A shield driving circuit for applying a potential equal to that of the auxiliary electrode to the sensor electrode;
The first changeover switch is configured to connect the auxiliary electrode to the shield drive circuit in the second connection state,
The vehicle obstacle detection according to claim 5, wherein the second changeover switch is configured to be able to open, ground, or connect the auxiliary electrode to a predetermined potential in the first connection state. apparatus. The vehicle obstacle detection device according to any one of claims 1 to 9, wherein the auxiliary electrode is disposed so as to surround the sensor electrode. The vehicle obstacle detection device according to any one of claims 1 to 10,
Traveling state detecting means for detecting the traveling state of the vehicle;
Deployment of the pedestrian protection airbag disposed on the hood of the vehicle based on the detection result detected by the vehicle obstacle detection device and the information indicating the running state detected by the running state detecting means. And a deployment control means for controlling the pedestrian protection airbag deployment control device. The deployment control means determines whether the obstacle detected by the vehicle obstacle detection device is a human body, indicates that the obstacle is a human body, and indicates that the vehicle is detected by the traveling state detection means. The pedestrian protection airbag deployment control according to claim 11, wherein, when it is detected that the vehicle is in a predetermined running state, the pedestrian protection airbag is deployed in accordance with the predetermined running state. apparatus. A plurality of the pedestrian protection airbags are arranged on the hood of the vehicle,
The deployment control means identifies the position of the detected obstacle based on the detection result from the vehicle obstacle detection device, and corresponds to the arrangement along the front-rear direction of the vehicle according to the position of the obstacle. The deployment of the airbag for protecting a pedestrian at a position is controlled. The airbag deployment control apparatus for protecting a pedestrian according to claim 11 or 12. The pedestrian protection airbag is arranged so that the rear end side of the hood of the vehicle can be flipped up or the surface of the hood of the vehicle can be covered. The airbag deployment control device for pedestrian protection according to claim 1.

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