JP4184232B2 - 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.

Contactless vehicle approaching object detection apparatus of the present invention includes a coil for generating a change in its coil impedance Zc is installed in the vehicle surface portion by the approach of the metal body as the approach of the vehicle near to the coil A grounding capacitor that has an electrode portion that is installed in the vicinity of the surface of the vehicle and causes a change in its own grounding capacitance Co due to the approach of a pedestrian as an approaching body in the vicinity of the vehicle, the coil, Based on both an AC power source that supplies power to the electrode unit , an electrical quantity related to a change in the coil impedance Zc caused by an eddy current flowing in the metal body, and an electrical quantity related to a change in the ground capacitance Co And a discrimination circuit for discriminating whether the approaching body is a metal body or a pedestrian .

  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 can be easily flattened, and can be easily installed on the front, rear and side of the vehicle, and it is far less costly than the conventional ultrasonic type, and widely monitors the surroundings of the vehicle without contact. be able to. 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.

In the present invention, in particular , whether the approaching body is a metal body or a pedestrian is determined based on both the electric quantity related to the change in the coil impedance Zc and the electric quantity related to the change in the ground capacitance Co. To do.

That is, according to the present invention , the capacitive approaching body detection sensor is 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.

In a preferred aspect 1 , in the above-described present invention , one end of the coil is fed from the other end of the AC power source whose one end is grounded, and the other end of the coil is connected to the electrode portion of the ground capacitor. The detection circuit forms a detection end for detecting the amount of electricity, and the determination circuit separates the approach of the metal body by the voltage increase at the detection end and the approach of the pedestrian by the voltage decrease at the detection end.

  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 preferred aspect 2 , in the above-described aspect 1 , the turn forming the other end of the coil essentially doubles as the electrode portion of the ground capacitor. For this reason, simplification or omission of an electrode part is attained.

In a preferred aspect 3 , in the above-described aspect 1 or 2 , it has a parallel connection capacitor having a capacitance C and connected in parallel with the coil, and the frequency f of the AC power supply is the frequency when there is no approaching body. When the inductance of the coil is L and ω = 2πf, it is set to an intermediate value between the first frequency value frc where ωC = 1 / ωL and the second frequency value frp where ω (C + Co) = 1 / ωL. The In addition, as this parallel connection capacitor, it is also possible to utilize the distributed capacitance of the coil, the parasitic capacitance between the coil and the vehicle body, and the parasitic capacitance between the coil and the electrode portion of the ground capacitor.

  According to the analysis and experiment, it has been found that the output voltage change due to the change of the coil impedance Zc and the ground capacitance Co, that is, the sensor sensitivity can be remarkably improved by doing so.

In a preferred aspect 4 , a plurality of the coils are arranged in order from left to right on at least the front or rear surface of the vehicle, and the determination circuit is related to the coil impedance Zc of each coil or the ground capacitance Co of the ground capacitor. The amount of electricity to be determined is determined for each 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 5 , in the above-described aspect 4 , the determination circuit determines the position of the approaching body in the left-right direction 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.

In a preferred aspect 6 , in the above-described aspect 4 or 5 , the coils are fed in parallel from the common AC power source. In this way, the AC power supply can be simplified.

In a preferred aspect 7 , in any one of the above-described aspects 4 to 6 , the determination circuit includes a multiplexer that sequentially selects an electric quantity related to the coil impedance Zc of each coil. In this way, the determination circuit can be simplified.

In a preferred aspect 8 , there is provided a compensation circuit that compensates for a change in the electrical quantity related to the coil impedance Zc due to a temperature change in the electrical resistance of the coil. In this way, it is possible to improve the sensitivity by reducing the variation in the output voltage due to the temperature change of the coil electrical resistance. For example, the temperature can be detected, the output voltage of the AC power supply can be changed based on the temperature, the detection voltage from the coil can be changed, and the frequency of the AC power supply can be changed according to the temperature. . Naturally, these changes are intended to prevent changes in output voltage due to temperature.

  In a preferred aspect, the temperature resistance change is substantially the same as that of the coil, and has a coil impedance Zc ′ substantially matching the coil impedance Zc of the coil when there is no approaching body and is connected in parallel to the parallel-connected capacitor. A dummy coil having a rate, and the capacitance C substantially matches the ground capacitance Co of the ground capacitor in the absence of the approaching body, and the dummy coil is an electromagnetic shield against the approaching body. Has been. In this way, it is possible to satisfactorily prevent the output voltage from varying due to the electrical resistance of the coil for detecting the approaching object changing with temperature.

  In a preferred aspect, the AC power supply outputs AC voltages having a plurality of frequencies to the coil, and the discrimination circuit processes the electric quantity separately for each frequency. In this way, the amount of electricity related to the eddy current, the capacitance to the ground, and the like can be calculated more precisely from the obtained amount of electricity.

In the preferable aspect 4 of the above-described aspect 3 , the frequency f of the AC power source is the bandwidth between the first frequency value frc (0%) and the second frequency value frp (100%). It is set within the range of 15 to 85% including the median value (50%). In this way, it has been found that the sensor sensitivity can be further improved.

In the preferred aspect 5 of the above-described aspect 3 or 4 , the ground capacitance Co of the ground capacitor is set to 10 to 300% of the capacitance C of the parallel-connected capacitor in the absence of the approaching body. . In this way, it has been found that the sensor sensitivity can be further improved.

  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 the microcomputer, which detects the type of obstacle (approaching object) 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. Very large value.

  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, in the sensor unit 2 of FIG. 12, a dummy coil 211 ′ having a resistance value equal to the coil 211 and a resistance temperature coefficient may be connected in parallel to the ground capacitor 214. The capacitor 212 and the capacitor 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 preferable. 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. The dummy coil 211 ′ may be a non-inductive coil and 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 infiltrates between the flexible printed wiring board 400 having the sheet coil and the fixed plate 5 and dries, and soil and sand are clogged around the sheet coil, thereby impairing the mobility of the sheet coil. Can be prevented. Even if muddy water enters between the bumper 4 and the flexible printed wiring board 400 by forming many holes in the portion of the flexible printed wiring board 400 where the spiral sheet coil 401 is not formed, this muddy water Can be easily discharged through the holes of the flexible printed circuit board 400 and the openings 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 (11)

A coil that is installed on the surface of the vehicle and generates a change in its coil impedance Zc by the approach of a metal body as an approaching body in the vicinity of the vehicle ;
A ground capacitor for generating a change in its earth capacitance Co by the approach of the pedestrian as the approach of the vehicle near a electrode portion installed on a surface portion of the vehicle adjacent the leading Symbol coil ,
An AC power source for supplying power to the coil and the electrode unit ;
Electrical quantity and the ground electrostatic pre Symbol approaching object based on both the electrical quantity associated with the change in capacitance Co is or or metal body associated with a change in the coil impedance Zc caused by eddy currents flowing through the metal body A discrimination circuit for discriminating whether it is a pedestrian ,
Contactless vehicle approaching object detection apparatus, characterized in that it comprises a. The approaching body detection device for a non-contact type vehicle according to claim 1 ,
One end of the coil is
Power is supplied from the other end of the AC power source with one end grounded,
The other end of the coil is
Connected to the electrode portion of the ground capacitor to form a detection end for detecting the amount of electricity,
The discrimination circuit includes:
A non-contact type approaching object detection device for a vehicle, wherein the approach of a metal body is classified by an increase in voltage at the detection end, and the approach of a pedestrian is separated by a decrease in voltage at the detection end. The approaching body detection device for a non-contact vehicle according to claim 2 ,
The turn forming the other end of the coil is
A non-contact type approaching body detection device for a vehicle, which essentially doubles as the electrode portion of the ground capacitor. In the non-contact vehicle approaching object detection device according to claim 2 or 3 ,
Having a parallel connection capacitor connected in parallel with the coil having a capacitance C;
The frequency f of the AC power supply is
When the inductance of the coil without an approaching body is L and ω = 2πf, the first frequency value frc where ωC = 1 / ωL and the second frequency value frp where ω (C + Co) = 1 / ωL A non-contact type approaching body detection device for a vehicle characterized by being set to an intermediate value. The approaching body detection device for a non-contact type vehicle according to any one of claims 1 to 4 ,
The coil is
A plurality of vehicles are arranged in order from left to right on at least the front or rear 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 coil or a ground capacitance Co of the ground capacitor is determined for each coil. The approaching body detection device for a non-contact vehicle according to claim 5 ,
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 5 or 6 ,
Each coil is
A non-contact type vehicle approaching object detection device, wherein power is supplied in parallel from the common AC power supply. In the non-contact-type vehicle approaching body detection device according to any one of claims 5 to 7 ,
The discrimination circuit includes:
A non-contact type vehicle approaching object detection device comprising a multiplexer that selects, in time sequence, an electrical quantity related to the coil impedance Zc of each coil. The approaching body detection device for a non-contact type vehicle according to any one of claims 1 to 8 ,
A non-contact type vehicle approaching object detection device comprising a compensation circuit that compensates for a change in an electrical quantity related to the coil impedance Zc due to a temperature change in the electrical resistance of the coil. The non-contact vehicle approaching body detection device according to any one of claims 1 to 9 ,
A dummy coil having a coil impedance Zc ′ substantially matching the coil impedance Zc of the coil in the absence of an approaching body and connected in parallel to the parallel-connected capacitor and having a temperature resistance change rate substantially the same as the coil Have
The capacitance C substantially matches the ground capacitance Co of the ground capacitor in the absence of the approaching body,
The dummy coil is electromagnetically shielded with respect to the approaching body. The approaching body detection device for a non-contact type vehicle according to any one of claims 1 to 10 ,
The AC power supply is
Output AC voltage of multiple frequencies to the coil,
The said discrimination circuit processes the said electric quantity separately for every said frequency, The non-contact-type approaching body detection apparatus for vehicles characterized by the above-mentioned.

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