JP2008175772A - Capacitive proximity sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitive proximity sensor device for vehicle capable of being preferably applied to detection of obstacles outside a vehicle, without misdetections, while being not reacting with rain drops or snow. <P>SOLUTION: The capacitive proximity sensor device includes two sets of electrodes 1a, 1b for generating electrostatic capacitance (electric field) in a detection area and detection circuits 2a, 2b connected to the electrodes, respectively, and detecting variation in the electrostatic capacitance. In the electrodes 1a, 1b, two are vertically arranged side-by-side so that the rain drops sequentially descend and drop. A ground electrode 4 is provided between the two of the electrodes 1a, 1b so as to establish the ground. The outputs of the detection circuits 2a, 2b are input and a determination circuit 3 is made. The determination circuit 3 performs the detection operation to determine that it is the detection of external disturbance, when only any one of the outputs of the detection circuits 2a, 2b performs the detection and also determine that it is the detection of external disturbance when any one of them performs the detection and is then restored and thereafter the other performs the detection and is then restored (in accordance with the time difference). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitance-type proximity sensor device that detects the presence of an object in a non-contact manner from a change in capacitance (electric field) within a detection region. The present invention relates to an improvement in determination operation when an object is detected in a detection area, such as when an obstacle is detected.

  As is well known, there is a capacitance type proximity sensor that detects the proximity of an object and the presence or absence of a nearby object in a non-contact manner. This capacitive proximity sensor generates a capacitance (electric field) in the detection area by electrodes, and detects the presence of an object (dielectric material) in a non-contact manner by detecting the change in capacitance. Most objects can be detected regardless of whether they are metal or non-metal. For example, as shown in Patent Document 1 or the like, for example, a configuration using an oscillation circuit is generally used to detect a change in capacitance, and the capacitance related to the electrode described above is an element of oscillation conditions. Thus, the oscillation circuit is configured, and the change in capacitance is detected by monitoring the oscillation state.

Japanese Patent Laid-Open No. 11-84019

  However, when a capacitive proximity sensor is arranged in a vehicle, for example, to detect an obstacle outside the vehicle, there is a problem of erroneous detection as pointed out in Patent Document 1. In other words, I want to detect an object or person approaching the vehicle, or an obstacle such as an object or person existing in the vicinity of the vehicle, but other objects such as raindrops or snowfall are not the obstacles. There is a problem that the electrostatic capacity may be changed by these other objects, causing false detection.

  Therefore, in Patent Document 1, the rate of change (rate of change) is also detected in relation to the change in capacitance, the rate of change related to obstacles such as objects and people, and the change related to other objects such as raindrops. By detecting the difference from the rate, false detection is prevented. However, in this case, since the change rate (differential value) of the capacitance is determined and discriminated, it reacts to the raindrops that slowly flow down and cannot be distinguished from the obstacles. There is a fault that false detection occurs when they are similar.

  There are many types of proximity sensors other than the capacitance type, and proximity sensors such as ultrasonic type, photoelectric type, and Doppler type are known. However, the ultrasonic type and the photoelectric type have a drawback that the detection becomes impossible when the raindrop or the snowfall adheres to the sensing part, or the detection region is changed and reduced. The Doppler method is similar to the capacitance method, and has a drawback of causing false detection when raindrops flow around the antenna.

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an object of the present invention is to provide a capacitive proximity sensor that can be preferably applied to the detection of an obstacle outside a vehicle without reacting to raindrops, snowfall, etc. and causing no false detection. To provide an apparatus.

  In order to achieve the above-described object, the capacitive proximity sensor device according to the present invention includes a pair of the electrode and the detection means, and the electrodes are arranged side by side, and the detection means Determining means for determining that the detection is a disturbance when only one of the outputs is detected and when either one is detected and then returned after being detected and then the other is restored after being detected Is provided.

  In addition, two electrodes are arranged side by side so that raindrops are transmitted sequentially. Furthermore, a ground electrode is provided between the two electrodes.

  Therefore, in the present invention, the electrode for generating the capacitance in the detection region and the detection means for detecting the change in the capacitance are provided in pairs, and the electrodes are arranged side by side, and the determination means The determination operation is performed at. In the determination operation, when only one of the outputs of the detection means is detected, it is determined that the disturbance is detected, and one of them returns after detection is detected, and then the other returns after detection is detected. If it is, it is determined that the disturbance is detected. In the latter case, a disturbance is detected when the time difference from the return of one to the detection of the other is a preset time difference (a certain width may be set), otherwise May be determined not to be a disturbance (detection of an object). Of course, when a signal with detection is output from both, it can be determined that the detection target is detected in the detection region.

  In the capacitive proximity sensor device according to the present invention, two electrodes for generating capacitance are arranged side by side in the detection region, and the determination unit performs the determination operation. The determination operation is performed by the detection unit. When only one of the outputs is detected, it is determined that disturbance is detected, and when either one returns after detection is detected and then the other returns after detection, it is determined that disturbance is detected. Therefore, it does not react to raindrops or snowfall and does not cause false detection. Therefore, it can be preferably applied to the detection of an obstacle outside the vehicle for a vehicle.

  FIG. 1 shows a preferred embodiment of the present invention. In this embodiment, the capacitive proximity sensor device includes electrodes 1a and 1b for generating capacitance in a detection region, and a detection circuit that detects changes in capacitance by connecting to the electrodes 1a and 1b. Two sets of 2a and 2b are provided. A detection signal is sent from each of the detection circuits 2a and 2b to the determination circuit 3, and the determination circuit 3 performs a determination operation when an object is detected in the detection area.

  Two electrodes 1a and 1b are arranged side by side so that raindrops can be transmitted sequentially. A ground electrode 4 for partitioning is provided between the electrodes 1a and 1b, and the ground electrode 4 is grounded. The two electrodes 1a and 1b and the ground electrode 4 are arranged at an appropriate interval, and the interval is set to a distance that prevents raindrops from adhering to two adjacent parties.

  The arrangement of the electrodes 1a and 1b is not necessarily limited to the arrangement in which the two are arranged one above the other. For example, when there is a need to prevent erroneous detection of a non-fluid object such as snowfall or dust, the electrodes 1a and 1b You may take the arrangement which arranges two on a plane.

  The detection circuit 2a has a resonance / coupling circuit 21a, an oscillation circuit 22a, and a detection / amplification circuit 23a connected in series in order, and outputs a change in the capacitance of the capacitance (electric field) generated by the electrode 1a. It is like that. Similarly, in the detection circuit 2b, a resonance / coupling circuit 21b, an oscillation circuit 22b, and a detection / amplification circuit 23b are connected in series, and the capacitance (electric field) generated by the electrode 1b changes in capacitance. Is output. That is, the electrostatic capacitance applied to the electrodes 1a and 1b is an element that is connected to the oscillation circuits 22a and 22b by the resonance / coupling circuits 21a and 21b to determine the oscillation conditions, and detects the frequency level of the oscillation circuits 22a and 22b. The amplifier circuit 23a, 23b converts the voltage into a DC voltage and outputs it.

  In the two detection circuits 2a and 2b, the oscillation frequencies in the oscillation circuits 22a and 22b are made different, which prevents mutual interference. That is, in the arrangement in which the electrodes 1a and 1b are arranged close to each other, the oscillation circuits 22a and 22b may cause interference. If there is no mutual interference, the same frequency may be set.

  In the oscillation circuits 22a and 22b, the frequency level changes according to the change in the oscillation condition due to the change in the capacitance. This is detected and amplified by the detection / amplification circuits 23a and 23b, and the change in the capacitance is The detection circuits 2a and 2b output the oscillation levels VL1 and VL2 as changes. The detection circuits 2a and 2b can be the same as the detection circuit in the capacitance proximity sensor device using a conventional pair of electrodes and a ground electrode.

  The determination circuit 3 is a so-called computer, takes in the outputs (oscillation levels VL1 and VL2) of the two detection circuits 2a and 2b, determines that only one of them is detected and is a disturbance detection, and either one is detected. Is detected after detection, and when the other returns after detection, a determination operation is performed to determine that a disturbance is detected according to the time difference.

  Now, when it rains, raindrops d1 may adhere to one electrode 1. At this time, the oscillation levels VL1 and VL2 change the capacitance only on the side where the raindrop d1 adheres, and the oscillation level on that side changes. Therefore, the determination circuit 3 can determine that the oscillation level has changed due to disturbance.

  In addition, when it rains, raindrops d2 may flow from top to bottom. At this time, the oscillation levels VL1 and VL2 are recovered by first changing the upper oscillation level VL1, and then returning by changing the lower oscillation level VL2. It can be determined that the oscillation level has changed due to a disturbance according to the time difference between the oscillation levels VL1 and VL2 (within a predetermined time).

  Specifically, as shown in FIG. 2, this capacitive proximity sensor device includes a main body 10, a cable 11 extending from the main body 10, and a connector 12 at the tip of the cable 11. Built in the main body 10, the connector 12 is connected to a vehicle security device.

  The main body 10 is molded with a resin material, and as shown in FIG. 3, the electrodes 1a and 1b are arranged in parallel and a ground electrode 4 is provided between them. The two electrodes 1a and 1b and the ground electrode 4 are connected to the circuit board 13, and the circuit board 13 is provided with detection circuits 2a and 2b and a determination circuit 3. The mold member is not limited to a resin material, and may be a non-conductive material such as rubber, wood, or glass.

  The electrodes 1a and 1b and the ground electrode 4 are formed on a strip having a predetermined length, and the width and length are appropriately set according to the detection region. The interval between these electrodes is set to about 2 mm, for example, and is set to an interval at which raindrops do not adhere to two adjacent parties.

  As shown in FIG. 4, the vehicle body can be installed in a structure in which the main body 10 is assembled to the upper edge portion of the door panel in the vehicle interior, and is fixed by a double-sided tape, Velcro (registered trademark), or the like. In assembling, it is preferable to take an arrangement where the distance from the outer plate of the vehicle is as far as possible, and to make the capacitance between the outer plate and the outer plate as small as possible. In this case, as shown in FIG. 5, the detection area S has a predetermined spread outside the door, but the detection area S can be secured large by being separated from the outer plate, and the degree of freedom of adjustment of the detection area S can be increased. Can do. Since the detection region S varies depending on the shape of the vehicle and the size of the electrodes 1a and 1b, the detection region S is adjusted appropriately for each vehicle.

  Moreover, as shown in FIG. 6, the installation to a vehicle can also take the structure which assemble | attaches the main body 10 to the center site | part of the door panel outside the vehicle, and the main body 10 is each provided about the front and back doors. In this case, since the main body 10 is fixed to the door panel, there is a disadvantage in that the capacitance between the outer panel and the main body 10 is increased. However, since the main body 10 is provided by connecting two front and rear doors, the side of the vehicle is more The detection area can be wide.

  By the way, the comparison with other types of proximity sensors will be described. However, in the same manner as in the present invention, when two are placed side by side and the determination operation is performed, there are the following problems, and it is against disturbances such as raindrops and snowfall. Cannot function effectively.

  In the ultrasonic type and photoelectric type, the transmission / reception part of the ultrasonic and light for detection is a configuration type that is exposed to the object to be detected. It becomes possible. Therefore, if raindrops, snowfall, etc. cover the transmission / reception part, it cannot be detected at all, or the detection area changes, so if one transmission / reception part is covered in the two-line configuration, detection is only possible on the other side. The determination operation of the determination circuit 3 according to the present invention cannot be performed.

  In that respect, the capacitance type according to the present invention makes it difficult to think that raindrops or the like cover the entire electrodes 1a and 1b, and the detection operation can be performed by correcting the oscillation conditions even when the electrodes 1a and 1b are covered. It can continue by 1a, 1b.

  In the Doppler system, the detection type is a wide-angle aperture that faces almost all directions in the immediate vicinity of the transmission / reception part because it is a type that receives the reflected wave from the object by directly transmitting radio waves for detection. In the two-line configuration, the overlap of the detection areas is large in the immediate vicinity of the transmission / reception part. Therefore, both react to raindrops and the like, and the determination operation of the determination circuit 3 according to the present invention cannot be performed.

  In that respect, since the electrostatic capacitance type according to the present invention is provided with a ground electrode plate 4 between the two electrodes 1a and 1b to form a partition, when the two electrodes 1a and 1b react together, an object is used. It can be determined that there is. In addition, since the amount of change in capacitance is small for raindrops and the like, sensitivity is set so that the raindrops are not detected to the extent that the raindrops are caught at the ends of the electrodes 1a and 1b. Is almost impossible.

  From the above, in the capacitive proximity sensor device according to the present invention, it can be said that detection and discrimination of raindrops and the like are more advantageous than other methods.

  As described above, in the present invention, the electrode for generating the capacitance in the detection region and the detection circuit for detecting the change in the capacitance are provided in pairs, and the electrodes 1a and 1b are arranged side by side. The determination circuit 3 performs a determination operation. The determination operation determines that a disturbance is detected when only one of the outputs of the detection circuits 2a and 2b is detected, and either one is detected. When it returns later and then returns after detection of the other, it is determined that the disturbance is detected according to the time difference, so that it does not react to raindrops, snowfall, etc., and no false detection occurs. Therefore, it can be preferably applied to the detection of an obstacle outside the vehicle for a vehicle. That is, when a signal with detection is output from both, it can be determined that the detection target is detected in the detection region.

It is a block diagram which shows suitable one Embodiment of the electrostatic capacitance type proximity sensor apparatus which concerns on this invention. It is a perspective view of a capacitive proximity sensor device. FIG. 3 is a cross-sectional view of the capacitive proximity sensor device shown in FIG. 2. It is a perspective view explaining arrangement | positioning to the vehicle of a capacitive proximity sensor apparatus. It is a top view explaining a detection area about the arrangement shown in FIG. It is a perspective view explaining the other example of arrangement | positioning to the vehicle of a capacitive proximity sensor apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode 2 Detection circuit 3 Judgment circuit 4 Ground electrode 10 Main body 11 Cable 12 Connector 13 Circuit board 21 Resonance / coupling circuit 22 Oscillation circuit 23 Detection / amplification circuit S Detection area

Claims (3)

In a capacitive proximity sensor device comprising: an electrode for generating a capacitance in a detection region; and a detecting means connected to the electrode to detect a change in capacitance.
The electrode and the detection means are provided as a pair, and the electrodes are arranged side by side and the output of the detection means is taken in, and only one of them is detected, and either one is detected An electrostatic capacity proximity sensor device comprising: a determination unit that determines that a disturbance is detected when the other is detected and then returned after the other is detected.   The capacitive proximity sensor device according to claim 1, wherein two electrodes are arranged side by side so that raindrops are sequentially transmitted.   The capacitive proximity sensor device according to claim 1, wherein a ground electrode is provided between the two electrodes.

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