JP4042973B2 - Non-contact type vehicle approaching object detection device - Google Patents

Description

  The present invention relates to an apparatus for determining non-contact of an object approach to a vehicle and its type, and more particularly to an apparatus for detecting the approach of a pedestrian.

  Pedestrian protection technology that activates a device to protect pedestrians when it is determined whether or not the collision target is a pedestrian at the time of a vehicle collision has been proposed, and its practical application has been studied. Therefore, there is a demand for a technique for determining whether or not an approaching body to a vehicle is a pedestrian. It is also expected to detect the approach of a vehicle, which is a metal body, before a collision for occupant protection.

  As a pedestrian discrimination technique, Patent Documents 1 and 2 describe pedestrians based on a change in capacitance between a collision target that is a conductor (including a resistor in this specification) and an electrode plate of a sensor. A method (capacitance type approaching body detection system) for detecting the approach of an approaching body having conductivity that electrically detects a difference in capacitance between the conductor and the conductor is proposed.

In addition, as a conventional method for detecting the approach of an obstacle to a vehicle in a non-contact manner, there has been a method of receiving reflected waves by irradiating ultrasonic waves.
JP 2000-177514 A JP 2000-326808 JP

  However, in the conventional capacitive approaching object detection method described above, the difference in electrostatic capacity between the human body and the metal body is small, and the inclination of the sensor output is in the same direction. Some have the disadvantage of being difficult to separate from humans. In addition, since it is necessary to operate at a high frequency in order to increase the output change accompanying the capacitance change, the influence of high frequency noise and external noise radio waves superimposed on the circuit output becomes large, and the discrimination accuracy decreases. There was also.

  In addition, although the above-described ultrasonic wave form has been put into practical use, it is difficult in terms of cost to dispose the ultrasonic wave oscillation receiver around the vehicle in the automobile field where the price competition is extremely fierce. It was only put into practical use. Furthermore, this ultrasonic format has a drawback that it is difficult to determine the type of approaching body.

  The present invention has been made in view of the above-mentioned problems, and provides a non-contact type approaching body detection device for a vehicle that is excellent in practicality in terms of manufacturing cost and capable of separating a metal body and a pedestrian well. That is the purpose.

A non-contact type approaching body detection device for a vehicle according to the present invention includes a coil that is installed on a surface portion of a vehicle and generates a change in its own coil impedance Zc due to the approaching of the approaching body that is a metal body in the vicinity of the vehicle, An AC power source for supplying power to the battery, a determination circuit for determining the approach of the metal body based on the amount of electricity related to the change in the coil impedance Zc, and an electrode installed on the surface of the vehicle in the vicinity of the seat coil A grounding capacitor that generates a change in its own grounding capacitance Co due to the approach of a pedestrian that is the approaching body in the vicinity of the vehicle having a part, and an AC power source that feeds the electrode part ,
The coil extends substantially horizontally in the left-right direction on a coil axis set in a substantially horizontal direction and in a direction substantially perpendicular to the installation portion of the coil of the vehicle; or Ri Do from flat sheet coil in a substantially rectangular shape having a long side arranged substantially horizontally in the longitudinal direction on the side surface of the vehicle,
The discriminating circuit discriminates whether the approaching body is a metal body or a pedestrian based on an electric quantity related to a change in the coil impedance Zc and an electric quantity related to a change in the ground capacitance Co. It is characterized by.

  That is, in this invention, the coil which forms an alternating current magnetic field around a vehicle is installed in the surface part of a vehicle, and the approach of the approaching body which has electroconductivity is detected by the alternating current impedance change of this coil.

  The coil of the present invention extends substantially horizontally in the left-right direction on the front or rear surface of the vehicle, with the coil axis set in a substantially horizontal direction and substantially perpendicular to the coil installation portion of the vehicle. It is composed of a substantially rectangular and flat sheet coil having a long side arranged substantially horizontally in the front-rear direction on the side surface of the vehicle, and can be easily embedded in a bumper, resin molding, etc. The aesthetic appearance is not impaired, and a wide range around the vehicle can be easily and non-contact-monitored at a much lower cost than the conventional ultrasonic type. In addition, since this coil can separate the metal body from the human body as compared with the ultrasonic type and the capacitance type, it prevents problems such as activation of the pedestrian protection device in response to the collision of the metal body. be able to.

  More specifically, when the AC magnetic field of the coil acts on the metal body, an eddy current flows through the metal body and the coil impedance Zc changes, but even if the AC magnetic field of the coil acts on the pedestrian, the eddy current is applied to the pedestrian. Can hardly be separated.

The metal body referred to here means a conductor having a specific resistance smaller than that of the human body, and may be a magnetic body or a non-magnetic body. Moreover, the electric quantity relevant to the coil impedance Zc resulting from the eddy current which flows into an approaching body can be measured by various methods. For example, the voltage drop of the load impedance element or the coil may be detected by supplying AC power to the coil from the constant voltage power source through the load impedance element. Moreover, you may detect the voltage drop of a coil by supplying with electricity to a coil from a constant current alternating current power supply. Furthermore, the resonant circuit including the coil impedance Zc may be self-excited to detect its frequency.
According to the present invention, a capacitive approaching body detection sensor is further disposed in proximity to the coil. In this way, it is possible to realize selective detection of a metal body by a change in the coil impedance Zc and selective detection of a human body by a change in the ground capacitance Co, and determine whether the approaching body is a metal body or a pedestrian. Further, it can be distinguished well.
The metal body also changes the ground capacitance Co of the electrode part. However, since the metal body can be selectively determined by the change of the coil impedance Zc, the capacitance sensor is a metal body if both sensors detect by detecting the approach of the pedestrian or the metal body, If only a capacitance sensor detects, it can distinguish that it is a pedestrian.
Furthermore, in the present invention, one end of the sheet coil is fed from the other end of the AC power source with one end grounded, and the other end of the sheet coil is connected to the electrode portion of the ground capacitor to form a detection end for detecting the amount of electricity. The discriminating circuit discriminates the approach of the metal body by the voltage rise at the detection end related to the change in the coil impedance Zc and the change in the ground capacitance Co, and the approach of the pedestrian by the voltage drop at the detection end. It is said.
In this way, the electrical quantity related to the eddy current and the electrical quantity related to the ground capacitance Co can be detected by one sensor device, and the circuit configuration can be greatly simplified. Particularly advantageously, the output voltage decreases when the pedestrian approaches and increases with the approach of the metal body, so that the pedestrian and the metal body can be easily and reliably separated by one sensor device. .
More specifically, as described above, the decrease in the AC impedance (eddy current increase) of the coil due to the approach of the human body is much smaller than that of the metal body. However, since the surface area of the human body is relatively large, the ground capacitance Co of the ground capacitor increases as the human body approaches. The increase in the ground capacitance Co reduces the potential at the connection end between the coil and the ground capacitor, for example, so that the approach of the human body can be detected.
When the metal body is considered to have the same area as the human body when viewed from the electrode part, the change in the electrostatic capacitance Co of the electrode part is equal to that of the human body. However, as described above, in the case of a metal body, the influence of the potential increase at the connection end due to the decrease in the AC impedance of the coil (increase in eddy current) is more dominant than the potential drop at the connection end due to the capacitance C. In addition, the direction of potential change at the connection end is opposite between the metal body and the human body, and discrimination between the two is possible. That is, when a metal body approaches, a decrease in coil impedance Zc due to eddy current and an increase in ground capacitance Co due to an increase in capacitance between the metal body and electrode due to the proximity of the metal body occur simultaneously. According to experiments, since the former is larger than the latter, in the case of approaching a metal body, the increase in output voltage due to the former cause is more dominant than the decrease in output voltage due to the latter cause. The output voltage was found to increase.

  In a preferred aspect 1, the sheet coil is a spiral sheet coil in which a turn conductor is formed in a spiral shape. In this way, the thickness of the sheet coil can be reduced while ensuring the necessary inductance and detection area, so that a wide detection area can be set around the vehicle with high detection sensitivity without impairing the vehicle aesthetics. Can do.

In a preferred aspect 2 , the sheet coils are arranged in a plurality of numbers in the vertical direction adjacent to each other on the front surface, rear surface, or side surface of the vehicle, and the determination circuit determines the electric quantity related to each coil impedance Zc of the plurality of sheet coils. Based on this, the low-position metal body that is low in height and does not interfere with vehicle travel is separated from the metal body that is high in height and interferes with vehicle travel.

  That is, in this aspect, for example, when two coils are arranged in the vertical direction of the vehicle and the coil impedance of the lower coil is determined to be larger than a certain threshold value by a certain threshold value, for example, a train line judge. As a result, it is possible to prevent a case where any metal body has fallen or is laid on a road that does not hinder travel and is erroneously detected as an obstacle.

In a preferred aspect 3, voltages of different frequencies are applied to the plurality of sheet coils, and the determination circuit extracts only the frequency component for each sheet coil and determines the amount of electricity. In this way, interference between these two coils can be reduced.

In a preferred aspect 4 , in the aspect 3 , the plurality of sheet coils are formed such that the magnetic flux formation direction is opposite. Thereby, since the magnetic fluxes of the two coils between the two sheet coils strengthen each other, the eddy current in the metal body can be increased and the detection sensitivity can be increased.

In a preferred aspect 5 , a plurality of the seat coils are disposed on the front or rear surface of the vehicle in the left-right direction or in the front-rear direction on the side surface of the vehicle. The amount of electricity related to the coil impedance Zc or the ground capacitance Co of the ground capacitor is determined for each sheet coil. In this way, since the ratio of impedance components that change due to the approach of a conductor such as metal can be increased in the total impedance of the coil, sensor sensitivity can be improved. Moreover, the effect which can also detect the position of the left-right direction or the front-back direction of an approaching body can be show | played.

In a preferred aspect 6 , in the aspect 5 , the determination circuit determines a left-right direction position of the approaching body based on the determination result. As a result, it is possible to take measures such as operating only the pedestrian protection device at the site where the approaching body approaches.

A preferred aspect 7 is that in the aspect 5 or 6 , the two sheet coils adjacent to or adjacent to each other are applied with voltages having different frequencies, and the discrimination circuit extracts only the frequency component for each sheet coil. Determine the amount of electricity. Thereby, there is no signal leakage between two adjacent sheet coils, and it is possible to suppress a change in the coil impedance Zc of one coil from affecting the coil impedance Zc of the adjacent coil.

A preferred aspect 8 is that in the aspect 5 or 6 , the two sheet coils adjacent to or adjacent to each other are formed such that the magnetic flux forming directions are opposite to each other. Thereby, since the magnetic fluxes of the two coils between the two sheet coils strengthen each other, the eddy current in the metal body can be increased and the detection sensitivity can be increased.

A preferred aspect 9 is the aspect 5 or 6 , in which the short sides of the two adjacent sheet coils adjacent to or adjacent to each other are adjacent to each other without overlapping or without a gap or without interposition of the electrode portion. In this way, even when the approaching body approaches the boundary between two adjacent sheet coils, the coil detection sensitivity is not lowered.

  Coil sensitivity can be improved by adjoining without gaps as much as possible. However, in this case, it is preferable that the magnetic flux forming directions of the two coils are opposite to each other, and in the case of overlapping, the magnetic flux forming directions of the two adjacent coils are preferably made equal. In the case of overlapping, for example, when the approaching body changes the coil impedance Zc of these two coils simultaneously, it can be determined that the approach is close to the coil boundary, and the change of the coil impedance Zc of one coil If it is more dominant than the other, it can be determined that the approaching body is approaching a portion other than the coil boundary portion of the one coil.

In a preferred embodiment 1 0 embodiment 5 or 6, wherein the determination circuit among the plurality of sheet coils arranged in the lateral direction or the longitudinal direction close to or adjacent to each other, the electric quantity of the sheet coil in the central portion And a threshold value that is different from the amount of electricity of the sheet coil at the end. That is, the central coil has adjacent coils on both sides thereof and is affected by the magnetic field of these adjacent coils. If the central coil and adjacent coils on both sides generate a magnetic field having the same frequency, the output is modulated due to the mutual inductance between these coils. On the other hand, in the endmost coil, the adjacent coil is only on one side, and the influence of the output modulation due to the influence of the mutual inductance is small.

  In addition, for example, when a vehicle is painted metallic, this metallic coating is made on one side without distinguishing between the inside and outside of the coil. In order to generate this, the width of the metallic coating surface through which the magnetic flux passes differs between the central coil and the peripheral coil, and this causes a change in output between the two coils. Therefore, in the present invention, the detection threshold value is changed in at least the central coil and the peripheral coils among the coils arranged on the left and right or front and rear. Preferably, the value of the coil impedance Zc differs because the shape of the vehicle body, which is a magnetic material, the size of the metallic coating surface through which the magnetic flux passes, etc. vary for each coil arranged on the left and right or front and rear. Therefore, if different optimum detection threshold values are set for each coil, the best detection accuracy can be obtained for each coil.

A preferred aspect 11 is characterized in that the electrode portion of the ground capacitor extends in parallel to the long side of the sheet coil in proximity to the top or bottom of the sheet coil. In this way, the detection area of the ground capacitor and the detection area of the seat coil are less likely to be shifted left and right, front and rear, or up and down, and the discrimination accuracy can be improved.

A preferred aspect 1 2 is the aspect 1 1 , since the electrode portion is formed wider than the outermost turn of the sheet coil, the sensitivity of the ground capacitor can be improved.

A preferred aspect 1 3 is the aspect 1 1 , since the outermost turn of the spiral sheet coil is formed wider than the other turns of the spiral sheet coil to constitute the electrode section, so that the sensitivity of the ground capacitor is improved. can do.

In a preferred embodiment 1 4, wherein the sheet coil is held in the resin bumper. In this way, since the coil is a large magnetic body and can be separated from the vehicle body with a large eddy current loss as much as possible, the detection sensitivity can be suppressed and the detection sensitivity can be improved. And eddy current loss can be reduced. Further, it is possible to prevent a decrease in aesthetics and to ensure electrical insulation of the coil. Preferably, the sheet coil is fixed to or integrally formed with the bumper. For example, the sheet coil is printed or attached directly to the bumper.

In a preferred embodiment 1 5 embodiment 1 4, wherein the sheet coil, the coil housing which is formed between the presser plate disposed on the rear surface of the bumper has a large specific resistance properties of the nonmagnetic and the bumper The chamber is accommodated so as to be relatively displaceable with respect to the bumper. In this way, even if the bumper is locally recessed, the sheet coil is relatively displaced with respect to the bumper and similarly has a recessed shape. Therefore, the conductor wire of the sheet coil is subjected to a large tension and may be disconnected. Absent. Also, the sheet coil can be reused when the bumper is replaced.

In a preferred aspect 16 , in the aspect 15 , the pressing plate has a number of holes penetrating in the thickness direction. For example, the pressing plate is formed in a mesh shape with resin. In this way, it is possible to prevent muddy water or the like from entering the sheet coil, drying it, and clogging up the earth and sand around the sheet coil to impair the mobility of the sheet coil.

In a preferred aspect 16 , in the aspect 15 , the pressing plate has a power supply line that feeds power to each sheet coil or an output signal wiring that takes out the potential from one end of each sheet coil. The output signal wiring is connected to the end of the sheet coil. In this way, wiring to the sheet coil can be simplified. For example, if an output signal wiring is connected to the outermost end and a power supply line is connected to the innermost turn, the sheet coil can be constituted by a single-layer flexible printed wiring board.

In a preferred aspect 16 according to the aspect 15 , the pressing plate has a flexibility equal to or higher than that of the bumper. In this way, the deformation of the bumper is not prevented.

A preferred aspect 17 is characterized in that the spiral sheet coil is formed of a flexible printed wiring board. In this way, a spiral sheet coil can be easily made. If this flexible printed circuit board is folded or flattened after being wound, a multi-layer spiral sheet coil can be produced, so that the number of turns can be increased without reducing the conductor line width. It is preferable to form the electrode part of the ground capacitor on the flexible printed wiring board at the same time.

Preferred aspect 18 is the aspect 17 in which the determination circuit is mounted on the flexible printed wiring board, so that the output signal wiring from the electrode portion of the coil or ground capacitor to the determination circuit can be shortened. Signal loss due to the impedance and electromagnetic noise superimposed on the output signal wiring can be reduced. An AC power supply can also be mounted on the flexible printed circuit board. In this case, a power supply line for connecting the AC power supply and the coil can be formed on the flexible printed circuit board as well.

Preferred embodiments 19 In embodiment 1 7, wherein the connection wiring for connecting the flexible printed wiring said discrimination circuit is wired to the substrate and the spiral sheet coil is that it is magnetically shielded. In this way, erroneous detection due to electromagnetic noise from the engine or the like can be reduced. Similarly, the power supply line from the AC power source to the coil can be shielded against electromagnetic waves.

In a preferred embodiment 2 0 embodiment 1 7, wherein the flexible printed circuit board has a plurality of the spiral sheet coils arranged in the longitudinal or lateral direction of the vehicle, the determination circuit, the coils of the spiral sheet coil The amount of electricity related to the impedance Zc or the ground capacitance Co of the ground capacitor is individually determined. That is, in this aspect, a plurality of spiral sheet coils are formed on the flexible printed wiring board. Thereby, the number of parts can be reduced, the number of assembly steps can be reduced, and the circuit wiring can be simplified. It is also easy to drastically increase the number of coils.

  Preferred embodiments of the present invention will be specifically described by the following examples.

An embodiment of the apparatus of the present invention will be described with reference to FIG.
(Description of circuit configuration)
Reference numeral 1 denotes an AC power source which is a low output impedance sine wave oscillator, 2 denotes a sensor unit, and 3 denotes a discrimination unit. The sensor unit 2 includes an AC impedance circuit 21 and a voltage drop detection resistor 22 connected in series with each other. The AC impedance circuit 21 is formed by connecting a coil 211 embedded in a bumper 4 of a vehicle, a capacitor 212, and a resistance element 213 in parallel. The AC power supply 1 is connected to one end of an AC impedance circuit 21, and the other end of the AC power supply 1 and the other end of the voltage drop detection resistor 22 are grounded. The voltage drop of the voltage drop detection resistor 22 is input to the determination unit 3. The resonance frequency of the parallel LC circuit including the coil 211 and the capacitor 212 is set to be higher than the oscillation frequency of the AC power supply 1.

  The discriminating unit 3 extracts the oscillation frequency component of the AC power source 1 from the output voltage of the sensor unit 2 which is a voltage drop of the voltage drop detection resistor 22 by a band pass filter, and then rectifies and smooths it to obtain a DC signal voltage. Then, it is converted into a digital signal and taken into a microcomputer, which detects the type of obstacle (approaching body) 5 and its approach.

Alternatively, the direct-current signal voltage is directly determined by a comparator circuit. When a comparator is used, the comparator circuit has a first comparator having a first threshold value that is larger than the DC signal voltage value when there is no obstacle by a predetermined value, and a DC signal voltage value when there is no obstacle. And a second comparator having a second threshold value that is smaller by a predetermined value. When the first comparator determines that the DC signal voltage is greater than the first threshold, it determines that the metal body is approaching, and the second comparator determines that the DC signal voltage is less than the second threshold. In this case, it is determined that a pedestrian is approaching. The circuit configuration itself of this type of discriminating unit 3 is well known and will not be described.
(Explanation of obstacle separation process)
A method of discriminating the proximity obstacle 5 by this circuit will be described with reference to FIGS. In these figures, L is the inductance of the coil 211, C is the capacitance of the capacitor 212, R is the resistance value of the resistance element 213, Ro is the resistance value of the voltage drop detection resistor 22, Vi is the output voltage of the AC power supply 1, Vo is a voltage drop of the voltage drop detection resistor 22 and is an output voltage of the sensor unit 2.

  FIG. 2 shows the case where the proximity obstacle 5 is an electrical insulator. The capacitor 212 may be provided separately from the coil 211, but may be the distributed capacity of the coil 211 or may include the distributed capacity of the coil 211. The resistor R may be provided separately from the coil L, but may be an internal resistance of the coil L itself. When the proximity obstacle 5 approaching the coil 211 is an electrical insulator, the output voltage Vo does not change because the proximity obstacle 5 does not electrically affect the sensor unit 2. In addition, when the approach of the proximity obstacle 5 is detected by an ultrasonic sensor or the like, the output voltage Vo of the sensor unit 2 does not change regardless of this approach, so the proximity obstacle 5 is not an electrical insulator, that is, a human being. Can be determined.

  FIG. 3 shows a case where the proximity obstacle 5 is a metal body such as aluminum. In this case, an eddy current flows through the metal body due to the approach of the metal body, and the coil impedance Zc of the coil 211 decreases, so that the combined AC impedance of the AC impedance circuit 21 decreases and the voltage drop of the voltage drop detection resistor 22, The output voltage Vo increases. That is, it can be determined that the metal body has approached when the output voltage Vo increases. When the obstacle 5 is a magnetic material such as soft iron, the inductance of the coil 211 increases. However, since the increase in the eddy current loss has a larger influence on the decrease in the coil impedance Zc of the AC impedance circuit 21 than the increase in the inductance of the coil 211, the voltage drop itself of the AC impedance circuit 21 decreases. Similarly, these metal bodies also increase the capacitance of the capacitor connected in parallel with the voltage drop detection resistor 22 and reduce the voltage drop of the voltage drop detection resistor 22 as in the case of the human body described later. However, since the influence of the decrease in the voltage drop of the AC impedance circuit 21 is more dominant due to the increase in eddy current loss due to the metal body than the decrease in the voltage drop of the voltage drop detection resistor 22 due to the increase in the capacitor capacity, when the metal body approaches. It has been found that the output voltage of the sensor unit 2 increases.

  FIG. 4 shows a case where the proximity obstacle 5 is a human body. Since the human body has a remarkably larger specific resistance (two digits or more) than the metal body, the eddy current caused by the coil 211 can be almost ignored. On the other hand, since the surface area of the human body is large, the capacitance C1 between the human body and the coil 21 (in terms of circuit, the connection point between the coil 21 and the voltage drop detection resistor 22) increases. Here, if the capacitance between the contact point of the AC impedance circuit 21 and the voltage drop detection resistor 22 and the human body and the human body is C1, and the ground capacitance of the human body is C2, the connection point is It is grounded through a series circuit of capacitances C1 and C2. As a result, this series-connected capacitance is connected in parallel to the voltage drop detection resistor 22 and their combined AC impedance is reduced, so that the voltage drop of the voltage drop detection resistor 22, that is, the output voltage Vo is reduced. That is, when the output voltage Vo decreases, it can be determined that the human body has approached. The connection point can be considered as an electrode portion of a capacitor (ground capacitor) connected in parallel with the voltage drop detection resistor 22. The turn conductor on the connection point side of the coil 211 should also serve as this electrode portion.

  FIG. 5 shows a calculation example of a change in the output voltage Vo when a human body, a metal, and an electrical insulator (other object) approach the coil 211, and FIG. 6 shows an actual measurement example.

  Next, as a comparative example, a graph showing a change in the AC impedance of the capacitance sensor unit and a change in the output voltage Vo when the electric insulator, metal body, and human body approach the capacitor C as a conventional capacitance sensor. A description will be given with reference to FIGS.

FIG. 7 shows a case where the electrical insulator approaches, in which case the output voltage Vo does not naturally change. FIG. 8 shows a case where the ground metal body approaches, and in this case, since the capacitance C1 is connected in parallel to the voltage drop detection resistor Ro, a voltage drop of the voltage drop detection resistor 22 occurs, and the output voltage Vo decreases. FIG. 9 shows a case where a person approaches. In this case, since the capacitances C1 and C2 connected in series are connected in parallel to the voltage drop detection resistor Ro as described above, it is as much as in the case of approaching a metal body. However, the voltage drop of the voltage drop detection resistor 22, that is, the output voltage Vo is lowered. FIG. 10 shows a calculation example of the change in the output voltage Vo when the human body, the metal, and the electrical insulator (other object) approach the coil 211 by the capacitance sensor. From the comparison between FIG. 5 and FIG. 10, it is understood that the sensor of this embodiment can provide excellent discrimination accuracy because the influence of the separation of the human body and the metal body on the output voltage Vo is opposite. .
(Modification 1)
Another modification will be described below with reference to FIG.

In this modification, the coil 211 wound around the bobbin 210 in FIG. 1 has a short axis and a large radius, and is opened forward. In this way, since the magnetic flux formed by the coil 211 can easily reach the target, the metal body detection sensitivity is improved. Reference numeral 100 denotes a metal cylinder having openings at both ends surrounding the coil 211, and is grounded. Thereby, this metal cylinder 100 can reduce the sensitivity of the coil 211 in the radial direction of the coil 211, and can relatively improve the forward sensitivity. The metal tube may be connected to a connection point between the coil 211 and the voltage drop detection resistor 22 to form the electrode portion of the ground capacitor described above. Of course, in this case, the metal cylinder 100 is not grounded. A metal plate 101 is connected to a connection point between the coil 211 and the voltage drop detection resistor 22, and extends in the vertical direction and the horizontal direction. In this way, the capacitance C1 between the metal plate 101 and the human body in front of the metal plate 101 can be increased, and the human body detection sensitivity can be improved.
(Modification 2)
In the above embodiment, the coil 211 of the AC impedance circuit 21 is installed in the bumper of the vehicle, but may be provided in another part. A plurality of bumpers may be separately provided at different positions.

Another embodiment of the apparatus of the present invention will be described with reference to FIG.
(Description of circuit configuration)
This embodiment is characterized in that an external capacitor 214 having a capacitance C4 is connected in parallel with the voltage drop detection resistor 22 in the circuit device shown in FIG.

  In FIG. 12, the coil 211 is equivalent to inductances L1 and L2, a resistance r, and a distributed capacitance C3. However, although the electrical resistance of the coil is ignored, in consideration thereof, the coil may be connected in series with the inductance L1.

  The inductance L1 is a so-called leakage inductance in which the magnetic flux does not link with the obstacle, and the inductance L2 is a so-called exciting inductance in which the magnetic flux links with the obstacle. r is a resistance element equivalent to eddy current loss, and is connected in parallel with the inductance L2. The distributed capacitance C3, which is the electrostatic capacitance between the turns of the coil 211, is equivalent to a capacitor connected in parallel with the inductances L1 and L2 connected in series with each other. In addition, there is a parasitic capacitance between the turn of the coil 211 and the ground. This parasitic capacitance is shown as capacitances C5 and C6 in FIG.

  The resistance element 213 and the resistance element 22 have a function of a bias resistor for setting an offset level of the output voltage Vo output from the connection end 200 that is an output end.

  C1 is the capacitance between the connection end 200 and the approaching body, C2 is the capacitance between the approaching body and the ground, the capacitance between the connection end 200 and the approaching body, rh is the inside of the approaching body The electric resistance, rh ′, indicates the ground resistance of the approaching body.

  As described above, the output voltage Vo that is the voltage at the connection end, that is, the output end 200 is amplified by the first-stage amplifier 300 and then extracted by the band-pass filter 301 by the oscillation frequency component of the AC voltage Vi output from the AC power supply 1. The DC signal voltage is input to the comparators 303 and 304 by the detection / smoothing circuit 302. The functions of the two comparators 303 and 304 are as described above.

  FIG. 13 shows an equivalent circuit obtained by simplifying the equivalent circuit shown in FIG. The coil 211, the capacitor 212, and the resistance element 213 are equivalent to an inductance L, a capacitance C, and a resistance R that are connected in parallel to each other, and an AC impedance between the connection end 200 and the ground is an electrostatic capacitance that is connected in parallel to each other. It is equivalent by a capacitance Co and a resistance Ro. However, the capacitance C shown in FIG. 13 is different from the capacitance C of the capacitor 212 shown in FIG. That is, the capacitance C shown in FIG. 13 includes the capacitance Co of the capacitor 212 and the capacitance C3 associated with the coil 211 shown in FIG. Further, the electrostatic capacitance Co is a combined electrostatic capacitance of the electrostatic capacitances C1 and C2 shown in FIG. 12, the parasitic capacitance C6 of the coil 211, and the electrostatic capacitance C4 of the capacitor 214. . Since the parasitic capacitance C5 of the coil 211 does not affect the output voltage Vo if the output resistance or wiring impedance of the AC power supply 1 is small, it can be ignored. The calculation formula of the output voltage Vo in this case is shown in Formula 1.

  Assuming that the resistances R and Ro in Equation 1 are infinite, the frequency value fo1 when the numerator term in Equation 1 is 0 is given by Equation 2, and the denominator term in Equation 1 is 0. The frequency value fo2 at this time is expressed by Equation 3. That is, when the resistances R and Ro are sufficiently large, the output voltage Vo is approximately 0 V when the frequency of the AC voltage Vi is the frequency value fo1, and the output voltage Vo is approximately 0 V when the frequency of the AC voltage Vi is the frequency value fo2. Become very large.

  The output voltage Vo when the frequency of the AC voltage Vi is variously changed in the formula 1 is shown by a solid line in FIG. Also, the case where the coil impedance of the coil 211 is reduced (corresponding to the approach of a metal body) and the case where the capacitance Co is increased (corresponding to the approach of a human body) are also shown.

  From FIG. 14, in the vicinity of the frequency values fo1 and fo2, it is sufficient when there is no approaching body or when the approaching body is an electrical insulator, when the approaching body is a metal body, and when the approaching body is a human body. It can be seen that discrimination cannot be performed. Further, when the influence of the resistors R and Ro is ignored, the frequency of the AC voltage Vi is -40% to + 25% centering on the band W between the frequency values fo1 and fo2, particularly the median value of the frequency values fo1 and fo2. It can be seen that suitable discrimination accuracy can be obtained in the range of.

  FIG. 15 shows the relationship between the frequency of the AC voltage Vi and the output voltage Vo when values appropriate as actual models are substituted for the resistors R and Ro. A suitable discrimination accuracy is obtained when the frequency of the AC voltage Vi is in the range of −40% to + 40% centering on the band W between the frequency values fo1 and fo2, particularly the median value of the frequency values fo1 and fo2. It can be seen that a more preferable discrimination accuracy is obtained in the range of% to + 25%, and a more preferable discrimination accuracy is obtained in the range of −25% to + 25%.

  In the above embodiment, capacitors 212 and 214 are externally attached. This is because the resonance frequency values fo1 and fo2 are adjusted to optimum values by externally attaching these capacitors. That is, by increasing the capacitance of these capacitors, the resonance frequency values fo1 and fo2 can be set to desired values even if the inductance of the coil 211 is not so large. However, in the equivalent circuit of FIG. 13, if the electrostatic capacitance Co is too large compared to the electrostatic capacitance C, the bandwidth between the frequency value fo2 and the frequency value fo1 becomes too wide and the sensitivity is lowered. . That is, as can be seen from FIG. 15, it can be understood that the output difference between the metal body and the human body can be increased as the inductance of the characteristic curve is larger in the bandwidth. That is, in the characteristic curve shown in FIG. 15, if the bandwidth is large, the change in the output voltage Vo becomes small even if the inductance L and the capacitance Co change.

  However, if the frequency values fo1 and fo2 are too close, a decrease in output sensitivity in the vicinity of these frequency values fo1 and fo2 affects the output voltage Vo. Therefore, the difference between the frequency values fo1 and fo2 is at least 100 kHz to 10 MHz, A range of 0.3 to 3 MHz is preferable. Here, since the increase in the capacitance Co decreases the frequency value fo2 relative to the frequency value fo1, the ground capacitance (referred to here as the capacitance of the ground capacitor) Co in FIG. It is suitable to set to 10 to 300% with respect to the coil parallel connection capacitance C in FIG.

  Another embodiment of the device of the present invention will be described with reference to FIG. FIG. 16 is a longitudinal sectional view of the front bumper of the vehicle cut vertically.

  Reference numeral 400 denotes a flexible printed circuit board pasted on the back surface of the bumper 4. On the front surface of the flexible printed circuit board 400, a rectangular spiral sheet coil 401 corresponding to the coil 211, an electrode line (ground capacitor in the present invention). Electrode portions) 402 and 403 are printed. In FIG. 16, a portion of the seat coil 401 that extends horizontally on the left and right sides of the vehicle is schematically illustrated. Reference numeral 404 denotes a determination unit or an AC power supply circuit mounted on the flexible printed wiring board 400.

  The spiral sheet coil 401 is a coil formed of a conductor layer formed in a spiral shape on the surface of the flexible printed wiring board 400 by printing or etching, and has two long side portions extending horizontally to the left and right, It is a rectangular spiral coil which consists of two short side parts extended perpendicularly | vertically.

  The electrode lines 402 and 403 correspond to the electrode plate 101 in FIG. 11 and are connected to the connection end (connection portion) 200 of the circuit to constitute one electrode of the capacitor forming the capacitance C1. . The electrode line 402 is disposed above and parallel to the upper long side portion of the spiral sheet coil 401, and the electrode line 403 is disposed below and parallel to the lower long side portion of the spiral sheet coil 401.

  FIG. 17 shows a partial front view when the flexible printed wiring board 400 having the spiral sheet coil 401 is viewed from the rear. However, the bumper 4 is not shown.

  Reference numerals 401 a, 401 b, and 401 c denote spiral sheet coils 401 shown in FIG. 16, which are arranged in a line on the left and right sides of the bumper 4. The gaps between the spiral sheet coils 401a, 401b, 401c are set as narrow as possible. This is to increase the coil impedance change when the approaching body approaches the vicinity of the gap.

  Reference numerals 402a, 402b, and 402c denote conductive lines 402 shown in FIG. 16, respectively, which form electrode portions of ground capacitors. Similarly, reference numerals 403a, 403b, and 403c denote conductive lines 403 shown in FIG. 16, respectively, which form electrode portions of ground capacitors. In this embodiment, a conductive line forming an electrode portion of the ground capacitor is not provided in the gap between the spiral sheet coils 401a, 401b, and 401c. This is to increase the coil impedance change when the approaching body approaches the vicinity of the gap.

  In this embodiment, the spiral sheet coil 401 a and the conductive lines 402 a and 403 a constitute the electrode part of the coil 211 and the capacitor 214 shown in FIG. 12, and the output voltage Vo is input to the first determination part 3. Similarly, the spiral sheet coil 401 b and the conductive lines 402 b and 403 b constitute another coil 211 and an electrode part of the capacitor 214, and the output voltage Vo is input to the second determination part 3. Similarly, the spiral sheet coil 401 c and the conductive lines 402 c and 403 c constitute another electrode part of the coil 211 and the capacitor 214, and the output voltage Vo is input to the third determination unit 3. That is, the number of determination units 3 equal to the number of spiral sheet coils is installed, and each determination unit 3 individually determines the output voltage Vo of each coil. In this way, changes in the coil impedance and the capacitance Co due to the approach of the approaching body are increased, so that the sensitivity can be improved. Moreover, when the approaching body which is a metal or a pedestrian is discriminate | determined, the left-right direction position of an approaching body can also be determined with the discriminated coil position. Naturally, the number of sets of the spiral sheet coil 401, the electrode lines 402 and 403, and the determination unit 3 can be appropriately selected. Further, the flexible printed wiring board 400 may be provided on the back bumper instead of the front bumper or on the side surface of the vehicle body. When the flexible printed wiring board 400 is provided on the side surface of the vehicle body, the spiral sheet coils are arranged in the front-rear direction.

  Moreover, it is preferable that the direction of the magnetic field produced by the two spiral sheet coils 401 adjacent to each other is opposite. In this way, sensitivity can be improved. The AC power source 1 and the determination unit 3 illustrated in FIG. 12 can be mounted on the flexible printed wiring board 400. In this case, since the distance of the wiring connecting the AC power source 1 or the determination unit 3 and the spiral sheet coil 401 can be shortened, the voltage drop of this wiring, superimposed electromagnetic wave noise, and resistance noise can be reduced. Although not shown, it is preferable that these wirings are covered with a grounded metal line and shielded by electromagnetic waves. Of course, each spiral sheet coil 401 may be manufactured individually, or instead of the spiral sheet coil, the coil 211 may be manufactured by concentrating the coil conductor on a short resin bobbin in the axial direction.

Note that the spiral sheet coil and the sheet coil are held, fixed, or integrated with a resin bumper. The bumper is not a eddy current loss and is not a magnetic material that strays the magnetic flux, especially in the electrical insulation of the coil and in improving the sensitivity. It is valid.
(Modification)
FIG. 18 shows another aspect of the processing circuit for the output voltage Vo of each spiral sheet coil 401 in FIG. Reference numerals 401 to 403 denote the capacitors 212 and 214 and the resistors 213 and 22 shown in FIG. In FIG. 12, a coil 211 that is a spiral sheet coil, capacitors 212 and 214, and resistors 213 and 22 constitute a sensor unit. In FIG. 18, three output voltages Vo individually output by each sensor unit are converted into time-sequential signals by a multiplexer 424 and processed by the determination unit 3 shown in FIG. 12. Each sensor unit is supplied with power from a common AC power source 1. Thereby, the circuit configuration of the AC power supply 1 and the determination unit 3 can be simplified.
(Modification)
Instead of processing the output signals of a plurality of sensor units using the multiplexer in a time-sequential manner by the common discriminating unit 3, the outputs of the sensor units are amplified by an amplifier and then subjected to analog addition or digital addition. The output signals of the sensor units may be time-sequential. However, in this case, the AC voltage Vi from the AC power source to each sensor unit is set to be applied in time sequence. In this way, the circuit configuration can be simplified.

  Another embodiment of the apparatus of the present invention will be described with reference to FIG. This embodiment shows a mode for compensating for a temperature change of the electric resistance (hereinafter also referred to as coil resistance) of the coil 211. According to the experiment, it is preferable that the coil resistance is small if the coil resistance is small. If the coil resistance is large, the variation of the coil resistance due to temperature change changes the output voltage Vo, so that there is a problem that the determination accuracy is lowered. It was.

  In the circuit shown in FIG. 19, the circuit configuration itself of the determination unit 3 that processes the output voltage Vo of the sensor unit 2 is the same as that shown in FIG. However, the determination unit 3 shown in FIG. 19 includes a thermistor 31 and a threshold voltage generation circuit 30 that outputs threshold voltages Vth1 and Vth2 linked to the voltage drop of the thermistor 31. In the threshold voltage generation circuit 30, the thermistor 31 is supplied with power from a constant current source, and threshold voltages Vth 1 and Vth 2 that change according to fluctuations in voltage drop due to temperature changes of the thermistor 31 are output to the comparators 303 and 304. To do. Of course, the threshold voltage generation circuit 30 reduces the voltage drop due to the temperature change of the thermistor 31 in a direction to suppress the fluctuation of the output voltage Vo due to the coil resistance fluctuation of the coil 211 caused by the temperature change from decreasing the determination accuracy. Based on this, the output voltage Vo is varied. In this way, it is possible to suppress deterioration in determination accuracy due to temperature fluctuations in the coil resistance of the coil 211.

Instead of changing the threshold voltages Vth1 and Vth2 of the comparators 303 and 304, the voltage amplification factor of the amplifier 300 and the output voltage Vi of the AC power supply 1 may be changed according to the voltage drop of the thermistor 31. A circuit that generates various temperature-linked outputs may be used instead of the thermistor. Alternatively, the output voltage of the rectifying / smoothing circuit 302 is converted into a digital signal and taken into a microcomputer, and the software performs equivalent temperature compensation processing. It is also possible.
(Modification)
In addition, as shown in FIG. 20, a pseudo sensor unit 2 ′ equivalent to the sensor unit 2 may be provided.

  The pseudo sensor unit 2 'has a circuit configuration equal to that of the sensor unit 2 shown in FIG. However, the coil 211 ′ and the grounding capacitor of the pseudo sensor unit 2 ′ (capacitor equivalent to the capacitor 214 in FIG. 19 and not shown) are always shielded in FIG. 19 by being electromagnetically shielded. It is assumed that each part circuit constant corresponding to a state where the approaching body is not approaching the sensor unit 2 shown. The coil 211 ′ built in the pseudo sensor unit 2 ′ has a temperature resistance change rate equal to that of the coil 211 of the sensor unit 2.

  In this way, since the output voltage Vo ′ of the pseudo sensor unit 2 ′ always outputs the output voltage Vo ′ when there is no approaching body, the output voltage Vo of the sensor unit 2 is more predetermined than the output voltage Vo ′. When the level is lower than the level, it is determined that the pedestrian is approaching. When the output voltage Vo of the sensor unit 2 is higher than the output voltage Vo ′ by a predetermined level or higher, it can be determined that the metal body is approaching. It is possible to satisfactorily prevent the coil resistance of 211 from fluctuating with temperature.

As the pseudo sensor unit 2 ′, any one of the plurality of sensor units provided in FIG. 18 having a similar circuit constant can be selected and used. In this case, the pseudo sensor unit 2 ′ is preferably arranged as far as possible from the sensor unit 2. This is because the probability that the same kind of approaching object approaches the plurality of separated sensor units 2, 2 ′ at the same time is small.
(Modification)
In addition, as shown in FIG. 21, the dummy coil 211 ′ may be connected in parallel to the ground capacitor 214 in the sensor unit 2 of FIG. 12. In this embodiment, the capacitors 212 and 214 have the same capacitance, the resistors 213 and 22 have the same resistance value, and the dummy coil 211 ′ has a coil impedance equal to the coil impedance of the coil 211 when there is no approaching body. It is suitable to have. However, the dummy coil 211 ′ is set such that the coil impedance does not change with respect to the approaching body by being electromagnetically shielded, and the resistance temperature change rate of the coil 211 and the dummy coil 211 ′ is set equal. In this way, the fluctuation of the output voltage Vo due to the temperature resistance change of the coil 211 and the fluctuation of the output voltage Vo due to the temperature resistance change of the dummy coil 211 ′ cancel each other, so that highly accurate discrimination is possible. In addition, the dummy coil may be a non-inductive coil, that is, a resistance element.

  Another embodiment of the device of the present invention will be described with reference to FIG. This embodiment shows a mode in which AC voltages Via, Vib, and Vic having different frequencies are applied to each sensor unit 2 when a plurality of sensor units 2 are arranged adjacently in order as shown in FIG.

  In FIG. 22, 1a, 1b, and 1c are AC voltages Vi, and output AC voltages Via, Vib, and Vic having different frequencies, respectively. The AC voltage Via is applied to the sensor unit 2a, the AC voltage Vib is applied to the sensor unit 2b, and the AC voltage Vic is applied to the sensor unit 2c. The sensor unit 2a outputs the output voltage Voa, the sensor unit 2b outputs the output voltage Vob, and the sensor unit 2c outputs the output voltage Voc. The output voltages Voa, Vob, and Voc are subjected to circuit processing by separate determination units 3, respectively. Naturally, the above-described band-pass filter incorporated in each determination unit 3 extracts only the frequency component of the output voltage to be processed by itself. In this way, the influence of a change in the current flowing in the adjacent coil 211 can be reduced, so that the determination accuracy and the right / left or front / rear position determination accuracy of the approaching body can be improved.

  Another embodiment of the device of the present invention will be described with reference to FIG. This embodiment is characterized in that in the circuit shown in FIG. 12, an AC voltage Vi obtained by mixing sine wave voltages of two frequencies f1 and f2 is applied to one sensor unit 2. The output voltage of the first stage amplifier 300 is input to the two band pass filters 301a and 301b. The band pass filter 301a extracts the AC voltage having the frequency f1, and the band pass filter 301b extracts the AC voltage having the frequency f2. The AC power source 1 may further output sinusoidal voltages having different frequencies. The AC voltage output from each bandpass filter can be separately detected and smoothed and processed by a comparator, or converted into a digital signal and processed by a microcomputer.

As shown in FIG. 15, with reference to the characteristic curve when there is no approaching body, the output voltage Vo with respect to the approach between the human body and the metal body in a band smaller than the frequency value f02 and a band region larger than the frequency value f02. Change is the opposite. Therefore, the frequency f1 is set to a predetermined value smaller than the frequency value f02, and the frequency f2 is set to a predetermined value larger than the frequency value f02. In this way, two signals can be obtained by one sensor unit 2. Therefore, if the AC smoothing voltage of the frequency f2 output from the bandpass filter 301b is inverted and added to the AC smoothing voltage of the frequency f1 output from the bandpass filter 301a, the determination accuracy can be further improved. it can.
(Modification)
In addition, both the frequencies f and f2 may be set between the frequency values fo1 and fo2. In this case, if the detection and smoothing voltage of the AC voltage having the frequency f1 output from the bandpass filter 301a and the detection and smoothing voltage of the AC voltage having the frequency f2 output from the bandpass filter 301b are added as they are, the determination accuracy is further increased. Can be improved. This is because noise power such as resistance noise mixed in these two signal powers is less than twice, for example, about 1.4 times by the above addition.
(Modification)
In addition, as described above, when a plurality of AC voltages are obtained, a plurality of values of the equation shown in Equation 1 are obtained for each frequency, and it is possible to directly calculate L or Co using this value. Become.

Another embodiment of the apparatus of the present invention will be described with reference to FIGS. This embodiment adjusts the capacitors 212 and 214 and the resistors 213 and 22 shown in FIG. 12 for each of the plurality of sensor units 2a, 2b, and 2c arranged adjacent to each other in the left-right direction. The frequency values fo1 and fo2 of 2a, 2b and 2c are made to coincide. The parasitic capacitance of the sensor unit 2a and the inductance of the coil 401a, the parasitic capacitance of the sensor unit 2b and the inductance of the coil 401b, the parasitic capacitance of the sensor unit 2c and the inductance of the coil 401c are It differs for reasons such as different mounting positions. Variations in the frequency values fo1 and fo2 are adjusted by adjusting the capacitance of the external capacitors 212 and 214. Thereby, even if the attachment position of sensor part 2a, 2b, 2c differs, frequency value fo1 and fo2 can be made to correspond. As a result, it is possible to perform signal processing by using the discriminating unit 3 having a bandpass filter having the same pass frequency by matching the output frequency of the AC power supply, and the discrimination accuracy can be improved, for example, in the case of multiplexer processing. it can.
(Modification)
In addition, instead of the above, an optimum AC voltage may be individually applied to each of the sensor units 2a, 2b, and 2c having different frequency values fo1 and fo2 from different AC power sources. In this case, the determination unit 3 may change the pass frequency of the bandpass filter 301 built in each determination unit 3 that individually processes each output voltage Vo output from each sensor unit 2a, 2b, 2c. .

Another embodiment will be described below with reference to FIG. In this embodiment, a coil 211e is provided on the upper half of the back surface of the bumper 4, a coil 211f is provided on the lower half of the back surface of the bumper 4, an electrode line 402 is provided above the coil 211e, and an electrode line 403 is provided below the coil 211f. It is what is pasted. Therefore, the coil 211e and the electrode line 402 constitute a circuit element of the upper sensor portion 2e, and the coil 211f and the electrode line 403 constitute a circuit element of the lower sensor portion 2f. In this way, the position of the approaching body in the height direction can be determined by comparing the output voltage Vo1 of the upper sensor unit 2e with the output voltage Vo2 of the lower sensor unit 2f. For example, when a metal body is buried on a road such as a rail, the metal body detection level of the lower sensor unit 2f is significantly higher than that of the upper sensor unit 2e. In such a case, it can be determined as a rail and not regarded as a collision object. In this case, the AC voltage Vi1 applied to the upper sensor unit 2e and the AC voltage Vi2 applied to the lower sensor unit 2f may be the same frequency, may be different frequencies, or may be sequentially applied. .
(Modification)
Further, in order to improve detection sensitivity, when the frequency of the AC voltage applied to both sensor units 2e and 2f is equal, the magnetic field formation direction of the upper coil 211e and the magnetic field formation direction of the lower coil 211f are opposite. preferable. Further, when the difference between the output voltage Vo1 of the upper sensor unit 2e and the output voltage Vo2 of the lower sensor unit 2f is small, the two are added and used for discrimination between the metal body and the pedestrian. N ratio can be improved.

Another embodiment will be described with reference to FIG. In this embodiment, a short side of the coil 211a adjacent to the left and right and a short side of the coil 211b are overlapped. In this way, when the approaching body approaches the boundary between the two coils 211a and 211b, both the two coils can be detected with high sensitivity. Therefore, when both of these two coils output a large output change in the same direction, it can be determined that the approaching body is large in the left and right directions or is approaching the boundary between these two coils. The two coils may be applied with an AC voltage Vi having the same frequency, may be applied with an AC voltage Vi having a different frequency, or may be applied with time in order.
When the AC voltage Vi having the same frequency is applied to two coils at the same time, it is preferable that the magnetic flux forming directions of two adjacent coils be equal.
Both coils can detect it with high sensitivity. Therefore, when both of these two coils output a large output change in the same direction, it can be determined that the approaching body is large in the left and right directions or is approaching the boundary between these two coils. The two coils may be applied with an AC voltage Vi having the same frequency, may be applied with an AC voltage Vi having a different frequency, or may be applied with time in order.
When the AC voltage Vi having the same frequency is applied to two coils at the same time, it is preferable that the magnetic flux forming directions of two adjacent coils be equal.

Another embodiment will be described with reference to FIG. This embodiment is characterized in that a flexible printed wiring board 400 in which a spiral sheet coil and a ground capacitor electrode portion (not shown) are formed is accommodated between the back surface of the bumper 4 and a fixed plate (pressing plate) 5. Yes. In this way, since the flexible printed wiring board 400 is covered with the fixing plate 5 and the bumper 4, protection of the flexible printed wiring board 400 is improved. The fixing plate 5 is a non-magnetic and electrically insulating resin plate member having rigidity that does not impair the deformability of the bumper 4 and is fixed to the back surface of the bumper 4. Preferably, the fixing plate 5 has a rib surrounding the flexible printed wiring board 400 at the periphery thereof on the surface of the flexible printed wiring board 400, and the rib is fitted to the back surface of the bumper 4 so that the fixing plate 5 is bumped. 4 is preferably supported. In this way, a gap in the front-rear direction in which the flexible printed wiring board 400 is movably held can be secured between the bumper 4 and the fixed plate 5, so even if the bumper 4 is locally recessed, In addition, the flexible printed wiring board 400 can be deformed, and the coil 211 of the flexible printed wiring board 400 can be prevented from being broken. The fixing plate 5 preferably has a flexibility equal to or higher than that of the bumper, and in this way, the deformation of the bumper is not suppressed.
(Modification)
A modification will be described with reference to FIG. FIG. 27 shows a schematic diagram in which the three spiral sheet coils 401 and the fixed plate 5 are disassembled. In this aspect, the fixed plate (presser plate) 5 shown in FIG. 26 is formed in a mesh shape by resin molding. In this way, muddy water or the like enters the front-rear direction gap between the spiral sheet coil 401 and the fixed plate 5, and dries to clog the earth and sand around the sheet coil, thereby impairing the mobility of the spiral sheet coil 401. Can be prevented. When the flexible printed wiring board 400 is used as the spiral sheet coil 401, the bumper 4 and the flexible printed circuit board 400 are formed by forming many holes in a portion of the flexible printed wiring board 400 where the spiral sheet coil 401 is not formed. Even if muddy water enters between the wiring board 400 and the muddy water, the muddy water can be easily discharged through the holes of the flexible printed wiring board 400 and the opening of the fixing plate 5. Of course, a cover surrounding the flexible printed wiring board 400 and the fixing plate 5 can be provided.
(Modification)
A modification will be described with reference to FIG. FIG. 27 shows a schematic diagram in which the three spiral sheet coils 401 and the fixed plate 5 are disassembled. In this embodiment, the fixed plate (pressing plate) 5 that is a resin plate shown in FIG. 26 includes, for example, a feed line 8 that feeds power to each spiral sheet coil 401 by insert molding or the like, and 3 that takes out a signal from each spiral sheet coil 401. Output signal wiring 9 is formed, the innermost end 408 of each spiral sheet coil 401 is individually connected to each end portion 81 of the feeder 8, and the outermost end 409 of each spiral sheet coil 401 is each output signal. Connected to each end of the wiring 9. These connections may be simple soldering or detachable using a connector mechanism. In this way, wiring to the sheet coil can be simplified, and the sheet coil can be a flexible printed wiring board having a simple conductor layer configuration.
(Other aspects)
In each of the embodiments described above, the coil 211 preferably has a coil axis that is set in a substantially horizontal direction and in a direction substantially perpendicular to the installation portion of the vehicle coil. Further, it is configured by a substantially rectangular and flat seat coil that has a long side that extends substantially horizontally in the left-right direction on the front or rear surface of the vehicle or that is disposed on the side surface of the vehicle approximately horizontally in the front-rear direction. This is particularly effective in improving the detection sensitivity of approaching objects. In particular, flat sheet coils can be easily embedded in bumpers, resin moldings, etc., so they do not impair the appearance of the vehicle, and at a much lower cost than conventional ultrasonic systems, and have a wide range around the vehicle. Can be easily monitored without contact.

  The width of the electrode lines 402 and 403 forming the electrode portion of the ground capacitor is preferably wider than the width of the outermost turn of the sheet coil. Moreover, it is preferable that the outermost turn of the spiral sheet coil is formed wider than the other turns.

It is a schematic circuit diagram which shows one aspect of this invention. FIG. 2 is an equivalent circuit diagram illustrating a case where an electrical insulator approaches the circuit of FIG. 1. It is an equivalent circuit diagram which shows the case where a metal body approaches the circuit of FIG. FIG. 2 is an equivalent circuit diagram illustrating a case where a human body approaches the circuit of FIG. 1. It is a characteristic view which shows the output characteristic (calculation example) by the circuit of FIG. It is a characteristic view which shows the output characteristic (measurement example) by the circuit of FIG. It is an equivalent circuit diagram which shows the case where an electrical insulator approaches the conventional electrostatic capacitance sensor. It is an equivalent circuit diagram which shows the case where a metal body approaches the conventional electrostatic capacitance sensor. It is an equivalent circuit diagram which shows the case where a human body approaches the conventional electrostatic capacitance sensor. It is a characteristic view which shows the output characteristic (example of calculation) by the conventional electrostatic capacitance sensor. It is a schematic circuit diagram which shows another aspect. FIG. 2 is a precise equivalent circuit diagram of the circuit of FIG. 1. It is the equivalent circuit schematic which simplified the equivalent circuit of FIG. It is a characteristic view which shows the ideal of the frequency-output voltage of the equivalent circuit of FIG. FIG. 14 is a characteristic diagram showing the actual frequency-output voltage of the equivalent circuit of FIG. 13. It is a longitudinal cross-sectional view which shows the sensor part arrangement | positioning state in another aspect. It is a front view which shows the sensor part arrangement | positioning state in another aspect. It is a circuit diagram which shows another aspect. It is a circuit diagram which shows another aspect. It is a circuit diagram which shows another aspect. It is a circuit diagram which shows another aspect. It is a circuit diagram which shows another aspect. It is a circuit diagram which shows another aspect. It is a circuit diagram which shows another aspect. It is a front view which shows the sensor part arrangement | positioning state in another aspect. It is a longitudinal cross-sectional view which shows the sensor part arrangement | positioning state in another aspect. It is a disassembled schematic diagram which shows the deformation | transformation aspect of FIG. It is a disassembled schematic diagram which shows the deformation | transformation aspect of FIG.

Explanation of symbols

1 AC power source 2 Sensor unit 3 Discriminating unit 21 AC impedance circuit 22 Resistive element 211 Coil 212 Capacitor 213 Resistive element 214 Capacitor

Claims (23)

A coil that is installed on the surface of the vehicle and causes a change in its own coil impedance Zc due to the approach of an approaching body that is a metal body in the vicinity of the vehicle;
An AC power source for supplying power to the coil;
A discriminating circuit for discriminating the approach of the metal body based on the amount of electricity related to the change in the coil impedance Zc;
Ground to generate a change in its earth capacitance Co by prior the approaching body in a pedestrian approaching close to the logger yl the vehicle near a electrode portion installed on a surface portion of the vehicle A capacitor,
An AC power source for supplying power to the electrode unit;
With
The coil extends substantially horizontally in the left-right direction on a coil axis set in a substantially horizontal direction and in a direction substantially perpendicular to the installation portion of the coil of the vehicle; or Ri Do from flat sheet coil in a substantially rectangular shape having a long side arranged substantially horizontally in the longitudinal direction on the side surface of the vehicle,
One end of the sheet coil is fed from the other end of the AC power source with one end grounded,
The other end of the sheet coil is connected to the electrode portion of the ground capacitor to form a detection end for detecting the amount of electricity,
The discriminating circuit discriminates the approach of the metal body by the voltage rise of the detection end related to the change of the coil impedance Zc and the change of the ground capacitance Co, and the approach of the pedestrian by the voltage drop of the detection end. A non-contact type approaching body detection device for a vehicle. The approaching body detection device for a non-contact type vehicle according to claim 1,
The non-contact type vehicle approaching body detection device according to claim 1, wherein the seat coil is a spiral sheet coil in which a turn conductor is formed in a spiral shape . In the non-contact type vehicle approaching body detection device according to claim 1 or 2 ,
The sheet coil is
A plurality of upper and lower adjacent to each other on the front or rear surface or side surface of the vehicle,
The discrimination circuit includes:
Based on the amount of electricity related to each coil impedance Zc of the plurality of seat coils, the low-position metal body that is low in height and does not interfere with vehicle travel is separated from the metal body that is high in height and interferes with vehicle travel. An approaching body detection device for a non-contact type vehicle. The approaching body detection device for a non-contact type vehicle according to claim 3 ,
The plurality of sheet coils are applied with voltages of different frequencies,
The non-contact type approaching body detection device for a vehicle, wherein the determination circuit extracts only the frequency component for each seat coil and determines the amount of electricity. In the non-contact vehicle approaching body detection device according to claim 3 ,
The non-contact type vehicle approaching body detection device, wherein the plurality of seat coils are formed so that a magnetic flux formation direction is opposite. The approaching body detection device for a non-contact vehicle according to any one of claims 1 to 5 ,
The sheet coil is
Plurally arranged close to or adjacent to each other on the front or rear surface of the vehicle, left or right, or on the side surface of the vehicle,
The discrimination circuit includes:
A non-contact type approaching body detection device for a vehicle, wherein an electric quantity related to a coil impedance Zc of each seat coil or a ground capacitance Co of the ground capacitor is determined for each seat coil. The approaching body detection device for a non-contact vehicle according to claim 6 ,
The discrimination circuit includes:
A non-contact type approaching body detection device for a vehicle, wherein a position of the approaching body in the left-right direction is determined based on the determination result. In the non-contact type vehicle approaching body detection device according to claim 6 or 7 ,
Two sheet coils adjacent to or adjacent to each other are applied with voltages of different frequencies,
The non-contact type approaching body detection device for a vehicle, wherein the determination circuit extracts only the frequency component for each seat coil and determines the amount of electricity. In the non-contact type vehicle approaching body detection device according to claim 6 or 7 ,
The non-contact type approaching body detecting device for a vehicle, wherein the two sheet coils adjacent to or adjacent to each other are formed so that a magnetic flux formation direction is opposite. In the non-contact type vehicle approaching body detection device according to claim 6 or 7 ,
Non-contact vehicle approaching object detection characterized in that the short sides of two sheet coils adjacent to or adjacent to each other overlap each other or are adjacent to each other without a gap or without interposition of the electrode part. apparatus. In the non-contact type vehicle approaching body detection device according to claim 6 or 7 ,
The discrimination circuit includes:
Of the plurality of sheet coils arranged in the left-right direction or the front-rear direction in proximity to or adjacent to each other, the amount of electricity of the sheet coil at the center and the amount of electricity of the sheet coil at the end are different. A non-contact type approaching object detection device for a vehicle, wherein a determination is made using a threshold value. The approaching body detection device for a non-contact type vehicle according to any one of claims 1 to 11 ,
The electrode portion of the ground capacitor is
A non-contact type vehicle approaching body detection device, wherein the approaching body detection device is arranged in parallel with a long side of the seat coil in proximity to the top or bottom of the seat coil. The non-contact proximity detection apparatus for a vehicle according to claim 1 wherein,
The electrode part is
A non-contact type vehicle approaching body detection device, wherein the approaching coil detection device is formed wider than the outermost turn of the seat coil. The non-contact proximity detection apparatus for a vehicle according to claim 1 wherein,
The outermost turn of the spiral sheet coil is
A non-contact type vehicle approaching object detection device, wherein the electrode portion is formed wider than the other turns of the spiral sheet coil. The non-contact proximity detection apparatus for a vehicle according to any one of claims 1 to 1 4,
The non-contact type vehicle approaching body detection device, wherein the seat coil is fixed to or integrally formed with a resin bumper. The non-contact proximity detection apparatus for a vehicle according to claim 1 5, wherein,
The sheet coil has a characteristic of being non-magnetic and has a large specific resistance, and is accommodated between the pressing plate disposed on the back surface of the bumper and the bumper so as to be relatively displaceable with respect to the bumper. An approaching body detection device for a non-contact type vehicle. In the non-contact type vehicle approaching body detection device according to claim 16 ,
The said press plate has many holes penetrated in the thickness direction, The non-contact-type approaching body detection apparatus for vehicles characterized by the above-mentioned. The approaching body detection device for a non-contact type vehicle according to claim 17 ,
The holding plate has a power supply line that supplies power to each sheet coil, or an output signal wiring that takes out the potential from one end of each sheet coil,
The power supply line or the output signal wiring is connected to an end portion of the seat coil. In the non-contact type vehicle approaching body detection device according to claim 16 ,
The non-contact type vehicle approaching body detection device, wherein the pressing plate has a flexibility equal to or greater than that of the bumper. The approaching body detection device for a non-contact vehicle according to claim 2,
The spiral sheet coil is
A non-contact type vehicle approaching body detection device comprising a flexible printed wiring board. The non-contact proximity detection apparatus for a vehicle according to claim 2 0, wherein,
The discrimination circuit includes:
A non-contact type vehicle approaching body detection device mounted on the flexible printed wiring board. The non-contact proximity detection apparatus for a vehicle according to claim 2 0, wherein,
The non-contact type approaching body detection device for a vehicle, wherein the connection wiring that is wired to the flexible printed wiring board and connects the discrimination circuit and the spiral sheet coil is magnetically shielded. The non-contact proximity detection apparatus for a vehicle according to claim 2 0, wherein,
The flexible printed wiring board is
A plurality of the spiral sheet coils arranged in the front-rear or left-right direction of the vehicle,
The discrimination circuit includes:
A non-contact type approaching body detection device for a vehicle, wherein an electric quantity related to a coil impedance Zc of each spiral sheet coil or a ground capacitance Co of the ground capacitor is individually determined.

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