JP2009085961A - Object sensor and opening/closing pinching sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an object sensor which has both functions as a contact sensor and an electrical capacitance sensor serving as a non-contact sensor and also has a simple structure, or a simple, high-reliability and responsive opening/closing pinching sensor that uses the object sensor. <P>SOLUTION: The object sensor includes a sensor body having the basic constitution as a contact sensor (having a piezo cable 11 as a sensor head), a detection circuit of the contact sensor (contact detection circuit 30) and a detection circuit of the electric capacitance sensor (approach detection circuit 40) using a conductor (shield mesh wire 18) of the sensor body as a detection electrode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an object detection sensor suitable for detecting pinching of an opening / closing body such as a sliding door of a vehicle, for example.

  For example, in a control system for an open / close body such as an electric sliding door of a vehicle or an automatic door of a building, an automatic closing operation (the open / close body automatically moves to a fully closed position even if the user stops the operation) to prevent the human body from being caught. In such a case, a pinch prevention function is provided that detects the occurrence of such pinching or the risk of such pinching and stops at least the closing operation of the opening / closing body or further reverses the operation (opening operation). . As one-box type automobile door systems, sliding doors and rear opening / closing doors (tailgates) attached to the left and right side surfaces are increasing. Such slide doors and rear opening / closing doors are large and heavy in shape, and therefore require a large force to open and close. In recent years, therefore, an automatic opening / closing system such as an electric sliding door that electrically opens and closes the door has become widespread. However, with automation, there is a possibility that a hand or a finger may be squeezed into the end of the door, or may be pushed by the door and fall down, and a pinching prevention function that effectively prevents this is desired.

  Conventionally, there are indirect detection and direct detection as a method of the detection device that performs pinching detection for preventing such pinching. Indirect detection is to indirectly detect pinching based on operation information (rotation position, rotation speed, etc.) of the drive motor of the opening / closing body and drive current, and direct detection is either close to the opening / closing end of the opening / closing body or A sensor that detects an object to be touched (such as a human body) is used. Among these, indirect detection has the disadvantage that it is relatively difficult to detect pinching quickly and reliably with a load as low as possible.

On the other hand, since direct detection directly detects an object, it has an advantage of relatively high reliability. However, since a conventional contact sensor such as a pressure sensitive switch is used as this type of sensor, the pinching is as low as possible. The load could not be detected early. For example, as shown in FIG. 9A, the pressure-sensitive switch has linear electrodes 2 and 3 formed by coating the inner surface of an insulating hollow rubber tube 1 with a conductive resin on the core wire. Are formed in a spiral shape, and the internal linear electrodes 2 and 3 are mutually connected by deformation of the rubber tube 1 due to the contact load of the object as shown in FIGS. 9 (b) and 9 (c). It operates by contacting and conducting. For this reason, the pressure sensitive switch is activated only when the object comes into contact with a certain pressure, and at that time, the pinching prevention function is finally activated.
In addition, pressure-sensitive switches enable reliable detection when a small object such as a finger or hand contacts within a narrow range.For example, a child or an elderly person wearing soft clothes has a wide contact area. When contact is made (when the contact load per area is small), the operation becomes unstable, and in some cases, the door may be pushed and fall down.

By the way, in general, sensors that detect the approach of an object in a non-contact manner include an optical type, a radio wave type, and a capacitance type. Among these, the optical type cannot arrange the detection area along the curved opening / closing end of an opening / closing body such as a vehicle door (that is, there is a dead band), and the radio wave type has directivity at the opening / closing end. There is a problem that it is difficult to limit only to the direction approaching the part, and the possibility of malfunction is high. On the other hand, the electrostatic capacitance type is promising in that it can be easily attached along a curved opening / closing end, has no dead band, and directivity can be easily controlled.
In view of this, the inventors are considering applying a capacitance sensor as a pinching detection device in an electric sliding door of a vehicle.
In addition, although the prior art example which applied the electrostatic capacitance sensor as the pinching detection apparatus in the electric slide door of a vehicle is not found, in patent document 1, the opening / closing state (including pinching) of a train door is used using the electrostatic capacitance sensor. A door opening / closing detection device to be detected is described. Patent Document 2 discloses a technique that uses a capacitance sensor to detect a human being caught in a shutter. In addition, as a high-performance capacitance sensor that provides a plurality of sets of electrodes constituting capacitance (capacitance) and detects an object with high sensitivity based on the difference in signal according to each capacitance, a patent There is a pachinko ball passage detector disclosed in Document 3. Patent Document 4 describes an elevator door safety device using a capacitance sensor or the like.

Japanese Patent Laid-Open No. 10-96368 JP 2001-264448 A JP 2001-318162 A International Publication No. 98/18710

However, when the above-described capacitance sensor is applied to an opening / closing body such as a vehicle door, there are the following problems.
(I) That is, there may be cases where an object with a low dielectric constant such as dried cardboard, glass equipment, or polystyrene foam cannot be detected. For example, a bag made of such an object or a user holding the baggage can be reliably inserted. There is a possibility that it cannot be detected.
(B) Moreover, a malfunction that turns on the sensor may occur due to adhesion of water having a high dielectric constant (water droplets due to rain or the like). In particular, if a large amount of water flows to the open / close end where the sensor is attached due to heavy rain, the detection signal is output even if the target does not exist, and the operation to close the open / close body stops. There is a possibility that a malfunction may occur in which the reversing operation moves in the opening direction against the user's intention.
(C) In a state immediately before the fully closed position where the open / close body approaches the fully closed position, the open / close end of the open / close body is joined or opposed to the frame portion (for example, when the vehicle slide door is fully closed). May cause a malfunction in which the sensor is turned on.

In addition, since the contact sensor such as the pressure sensitive switch described above performs detection regardless of the dielectric constant of the object, the above problems (a) to (b) do not occur. Thus, the inventors are considering using a contact sensor such as a pressure-sensitive switch and a capacitance sensor to complement each other's disadvantages, but the structure with a simple configuration with two sensors is complicated. Therefore, there is a problem that the cost is increased and the productivity is lowered.
For this reason, the present invention has both a function as a contact sensor and a function as a capacitance sensor which is a non-contact sensor, and an object detection sensor having a simple configuration, or a simple, reliable and responsive function using the same. An object of the present invention is to provide a high opening / closing body pinching detection device.

The object detection sensor of the present invention includes a sensor body having a sensor head in which a resistance or voltage between conductors forming an internal pair is changed by deformation of an object, and changes.
A contact detection circuit that detects contact of an object with the sensor body and outputs a contact detection signal based on a change in resistance or voltage between the conductors;
An approach detection circuit that uses the conductor of the sensor head as a detection electrode and detects an approach of an object to the sensor body and outputs an approach detection signal based on a change in stray capacitance formed by the detection electrode; It is to be prepared.

In the object detection sensor of the present invention, when an object such as a human body having a high dielectric constant approaches the sensor body, the stray capacitance formed by the detection electrode changes, so that the approach of the object is detected by the approach detection circuit. A detection signal is output. Even if the object has a low dielectric constant, if the sensor head is deformed by contact with the sensor body, the resistance or voltage between the conductors of the sensor head changes, so the contact of this object is detected by the contact detection circuit. A contact detection signal is output. That is, the object detection sensor of the present invention has both a function as a contact sensor and a function as a capacitance sensor that is a non-contact sensor.
For this reason, by complementing the shortcomings of the sensor methods, it is possible to detect an object with high reliability and high responsiveness as much as possible. For example, in the case of an adverse condition such as a rainy state or the state immediately before full closure, the function of the proximity detection circuit (that is, the function of the capacitance sensor) is invalidated, or the sensitivity of the proximity detection circuit is relatively set. By setting it to a low value, the malfunction of the capacitance sensor due to water or the like is prevented, while the object is reliably detected by the function of the contact sensor to maintain reliability. Also, when it is not an adverse condition such as a rainy condition, the function of the proximity detection circuit (that is, the function of the capacitance sensor) is set to high sensitivity, and the object such as a human body having a high dielectric constant is responsive without contact. Highly detectable. Even an object with a low dielectric constant can be detected with high reliability by at least the function of the contact sensor.

  As described above, the object detection sensor of the present invention is a simple device that can detect an object with high reliability and responsiveness as much as possible, while also using the conductor constituting the contact sensor as the detection electrode of the capacitance sensor. Therefore, the number of parts can be reduced compared with the case where a contact sensor and a capacitance sensor are separately provided, which is advantageous in terms of cost, productivity, and installation space. .

The sensor head and the contact detection circuit constituting the contact sensor may be of a pressure sensitive switch type. That is, the sensor head is arranged such that a pair of deformable conductors is separated from each other in a natural state, and the contact detection circuit is configured such that the conductors contact each other and the resistance between the conductors The contact detection signal may be output by detecting the contact of the object with the sensor main body based on the decrease of the sensor.
However, it is desirable that the sensor head has, for example, the following cable shape. That is, in the case of a pressure sensitive switch type, the sensor head is formed by spirally attaching a plurality of linear electrodes to the inner surface of an insulating tube, and the linear electrodes function as the conductor. It is a cable-like thing, and the approach detection circuit preferably uses the linear electrode as the detection electrode. Thus, when the sensor head is in the form of a cable, the entire sensor body can be easily attached along the opening / closing end of the opening / closing body, making it more suitable as a pinch detection device for the opening / closing body. It becomes.

According to another preferred aspect of the present invention, the sensor body includes a differential correction detection electrode disposed on the back side of the sensor head (opposite side to detect the approach or contact of an object), and the approach detection The circuit calculates a difference value between a value corresponding to the stray capacitance constituted by the detection electrode and a value corresponding to the stray capacitance constituted by the difference correction detection electrode, and based on the change of the difference value The approach detection signal is output by detecting the approach of the object to the sensor body. In this mode, environmental changes such as the state of water droplet adhesion and adverse effects of temperature drift are suppressed, and highly sensitive non-contact detection is possible.
When the sensor head is in a cable shape, it is desirable that the difference correction detection electrode is also in a cable shape and is arranged along the back side of the sensor head. If it does in this way, the high performance sensor main body provided with the detection electrode for difference correction will become a cable shape as a whole, and there exists an advantage which becomes easy to attach along the opening-and-closing end part of an opening-and-closing body.
Further, it is preferable that an elastic body is interposed between the sensor head and the difference correction detection electrode in the sensor body. According to this aspect, even when the difference correction detection electrode is difficult to deform together with the sensor head, only the sensor head can be sufficiently deformed, and the reliability as a contact sensor is improved.

  In another preferred aspect of the present invention, the shield for shielding the sensor body so as to cover a non-detection range including at least a back side of the sensor body (a side opposite to a side for detecting approach or contact of an object). This is an embodiment in which electrodes are disposed. In this case, the directivity on the detection side can be particularly enhanced by the shielding action of the shield electrode, and the possibility of malfunction when a dielectric approaches a side surface that is not a desired detection area can be basically reduced.

Next, the opening / closing body pinching detection device of the present invention includes the object detection sensor of the present invention, and the sensor main body of the object detection sensor is attached to the opening / closing end portion of the opening / closing body and may be pinched by the opening / closing body. The object in is detected.
Here, the “opening and closing body” may be a vehicle door (including a tailgate), a vehicle trunk lid, a sunroof window, a building door or window, an elevator door, or a safe lid. Also good. In addition, the “opening / closing end” is an end edge of the opening / closing body that forms one edge (movable edge) of the opening when the opening / closing body is opened. , A portion that is joined or opposed to the other edge (the edge on the fixed side) of the opening.

  According to the opening / closing body pinching detection apparatus of the present invention, since the object detection sensor of the present invention is used, it is possible to detect pinching with high reliability and as much responsiveness as possible while having a simple configuration. For example, in the case of an adverse condition such as a rainy state or the state immediately before full closure, the function of the proximity detection circuit (that is, the function of the capacitance sensor) is invalidated, or the sensitivity of the proximity detection circuit is relatively set. Setting it to a low value prevents malfunctions caused by water, etc. (the problem that the closing operation stops or reverses when no pinching has occurred), while pinching is reliably detected by the contact sensor function. And maintain reliability. Also, when it is not an adverse condition such as a rainy condition, the function of the proximity detection circuit (that is, the function of the capacitance sensor) is set to high sensitivity, and the object such as a human body having a high dielectric constant is responsive without contact. As a result, it is possible to significantly reduce the possibility of occurrence of problems such as a child being pushed by the sliding door and falling. Further, even an object with a low dielectric constant (for example, a baggage such as a dry cardboard) can be detected with high reliability by at least the function of the contact sensor and can be reliably prevented from being caught.

  According to the present invention, an object detection sensor having a function as a contact sensor and a capacitance sensor that is a non-contact sensor and having a simple configuration, or simple, reliable and responsiveness using the same. A high opening / closing body pinching detection device can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
First, the first embodiment will be described.
This example is a pinching detection device that detects, by an object detection sensor, a human body or the like (object) that approaches a position range that may be pinched by a slide door (opening / closing body) in a four-wheeled vehicle.
FIG. 1 is a cross-sectional view showing a configuration of a sensor body 10 of the object detection sensor of this example, and FIG. 2 is a diagram showing a detection circuit of the object detection sensor of this example. FIG. 3A is a timing chart for explaining the operation of the detection circuit, and FIG. 3B is a diagram showing a deformed state of the sensor body 10 due to contact with an object. FIG. 8 is a view for explaining a mounting state of the sensor main body 10, and is a view of the slide door 5 to which the sensor main body 10 is mounted as viewed from the end face side.

As shown in FIG. 1, the sensor body 10 has a cable-like electrode 12 arranged in parallel on the back side of the piezo cable 11 corresponding to the sensor head, and the shield electrode 13 is placed on the back side and side surface (mainly the cable-like electrode 12). It is a cable-like one (covered with a uniform cross-section) that is disposed so as to cover the back side and is further covered with a protective outer cover 14 made of an insulating resin. It was manufactured to a length approximately equal to the total length of.
In this case, an elastic body 15 made of rubber is interposed between the piezo cable 11 and the cable-like electrode 12. When such an elastic body 15 is provided, for example, as shown in FIG. 3B, the piezo cable 11 is sufficiently easily deformed so as to be locally bent by the contact load of the object. Since such a piezo cable 11 is more sensitive to deformation in the bending direction than compression, if it can be deformed as shown in FIG. 3B, a smaller contact load can be detected and sensitivity is improved. Rise.
Further, the surface of the sensor body 10 has an arc shape along the circular outer periphery of the piezo cable 11 on the detection side (upper side in FIG. 1) for detecting the approach or contact of an object, and is opposite to the detection side. The back surface (the lower surface in FIG. 1) is a flat mounting surface 14a. The sensor main body 10 is attached to the end face of the slide door 5 of the automobile, for example, as shown in FIG. Mounted across.
Further, the protective outer skin 14 can be formed of, for example, foam rubber used for automobile weather strips or the like.

The piezo cable 11 has a structure similar to that of a general coaxial cable, in which an insulator between a core wire and a shield net is replaced with a piezo polymer. That is, as shown in FIG. 1, a core wire 16 made of a conductor (for example, copper), a piezo polymer 17 provided so as to cover the outer periphery of the core wire 16, and an outer periphery of the piezo polymer 17 are provided. A shield net 18 made of a conductive material and an insulating protective sheath 19 provided so as to cover the outer periphery of the shield net 18. The piezo cable 11 generates a voltage corresponding to the deformation amount between the core wire 16 and the shield net 18 due to the piezoelectric effect of the piezo polymer 17 due to deformation (compression, bending, etc.) due to external pressure. The shield net 18 of the piezo cable 11 is used as a detection electrode (A electrode) of a capacitance sensor, as will be described later.
The cable-shaped electrode 12 includes a core wire 20 made of a conductor and an insulating protective sheath 21 provided so as to cover the outer periphery of the core wire 20. As will be described later, the core wire 20 of the cable electrode 12 is used as a difference correction detection electrode (B electrode) of the capacitance sensor.
The shield electrode 13 (S electrode) is formed of, for example, an aluminum foil and has a U-shaped cross section with an opening on the detection surface side. The back side of the sensor body 10 (in this case, the back side of the cable electrode 12) It arrange | positions so that the non-detection range containing may be covered.

The sensor main body 10 having such a configuration can be made sufficiently small, has sufficient flexibility, can be easily curved in the longitudinal direction, and follows the shape of the end portion of the slide door 5. And it is possible to arrange it compactly. Further, due to the shielding action of the shield electrode 13, only the detection surface side (that is, the side of the position range that is mainly opposed to the end portion of the sliding door 5 and is likely to be sandwiched between the sliding doors 5) is made highly sensitive. It becomes possible to make the surface of the surface basically insensitive.

Next, the detection circuit will be described. In FIG. 2, the contact detection circuit 30 that constitutes a contact sensor is above the one-dot chain line, and the proximity detection circuit 40 that constitutes a capacitance sensor that is a non-contact sensor below the one-dot chain line.
The contact detection circuit 30 amplifies a voltage generated between the core wire 16 and the shield network 18 of the piezo cable 11 by an amplifier circuit composed of three OP amplifiers (operational amplifiers) A1 to A3. The signal is output as a piezo sensor output (contact detection signal) to a controller (not shown) of the slide door 5. The controller determines that a contact has been detected when the output of the contact detection circuit 30 (piezo sensor output) reaches a level exceeding a prescribed threshold value, for example.
The amplifier circuit needs to have high input impedance, and the OP amplifiers A1 and A2 are also connected to the capacitance sensor side circuit (approach detection circuit 40). A small capacitance between the input terminal and ground should be used. Also, the resistor R1 shown in FIG. 2 is for adjusting the attenuation characteristic of the voltage generated in the piezo cable 11.

The OP amplifier A3 constitutes a differential amplifier, and the output of the OP amplifier A1 (voltage value corresponding to the potential of the core wire 16) and the output of the OP amplifier A2 (voltage value corresponding to the potential of the shield network 18). ) Is amplified and used as the piezo sensor output. In this case, since the shield net 18 of the piezo cable 11 is connected to the proximity detection circuit 40 as a detection electrode (A electrode), the stray capacitance formed between the core wire 16 of the piezo cable 11 and the ground is also described later. Charge / discharge is repeated in the same manner as the stray capacitances Ca and Cb (periodic charge transfer is received). However, the effect of the charging / discharging is canceled by the operation of the OP amplifier A3 (differential amplifier), and only when a potential difference is generated between the core wire 16 and the shield net 18 (that is, the piezo cable 11 is connected). The contact detection circuit 30 outputs an output exceeding the threshold value (piezo sensor output) only when the object to be deformed contacts.

On the other hand, as shown in FIG. 2, the approach detection circuit 40 includes analog switches S1 to S13 that are periodically operated by a drive circuit (not shown), OP amplifiers A4 to A7, and the like.
In FIG. 2, the capacitor symbol indicated by Ca is a capacitance formed between the ground or the vehicle body that is the ground potential, the human body that is the detection target, and the A electrode (the shield mesh 18 described above). (So-called stray capacitance). Similarly, the capacitor symbol indicated by the symbol Cb indicates the capacitance formed between the vehicle body, the human body, and the like and the B electrode (the core wire 20 described above). A symbol Cs indicates a capacitance formed between the vehicle body or the human body and the S electrode (the shield electrode 13 described above). Further, the symbols Cas and Cbs indicate the capacitance between the S electrode and the A electrode and between the S electrode and the B electrode, respectively. However, in the case of this example, since the A electrode, the B electrode, and the S electrode are basically controlled to the same potential, the capacitances Cas and Cbs do not appear apparently.

The analog switches S1 and S2 constitute a pulse drive circuit for the A electrode, and are driven by a drive circuit (not shown) to switch the connection of the A electrodes at a predetermined cycle. Among them, the switch S1 opens and closes a line connecting the A electrode and the ground, and the switch S2 opens and closes a line connecting the detection electrode A and the inverting input of the OP amplifier A4.
The analog switches S3 and S4 constitute a pulse drive circuit for the B electrode, and switch the connection of the B electrode at a predetermined cycle. Among them, the switch S3 opens and closes a line connecting the B electrode and the ground, and the switch S4 opens and closes a line connecting the B electrode and the inverting input of the OP amplifier A5.
The analog switches S5 and S6 constitute a pulse drive circuit for the S electrode, and switch the connection of the S electrode at a predetermined cycle. Among them, the switch S6 opens and closes a line connecting the S electrode and the ground, and the switch S5 opens and closes a line connecting the S electrode and the reference voltage line.

The analog switches S1 and S3 are periodically turned on as shown in the fourth row from the top in FIG. Similarly, the analog switches S2 and S4 are periodically turned on, but are turned on when the analog switches S1 and S3 are turned off, as shown in the third row from the top in FIG.
Further, as shown in the second row from the top in FIG. 3A, the analog switch S5 is turned on at a timing after the analog switches S1 and S3 are turned off and before the analog switches S2 and S4 are turned on. After the analog switches S2 and S4 are turned off, they are turned off at a timing before the analog switches S1 and S3 are turned on. Also, the analog switch S6 is turned on and off at exactly the opposite timing as the analog switch S5, as shown in the first row from the top in FIG.

The OP amplifier A4 constitutes an A electrode charge integration circuit, and a capacitor Cc1 and an analog switch S7 are connected in parallel between the output and the inverting input of the OP amplifier A4. The non-inverting input of the OP amplifier A4 is connected to the reference voltage line, and a reference voltage is applied. The analog switch S7 is a switch that opens and closes between both terminals of the capacitor Cc1 (that is, between the output and the inverting input of the OP amplifier A4). As shown in the fifth row from the top of FIG. It is turned on at the same time as S1 and S3 and turned off at the timing immediately after the switches S1 and S3 are turned off.
The OP amplifier A5 constitutes a charge integration circuit for the B electrode, and a capacitor Cc2 and an analog switch S8 are connected in parallel between the output and the inverting input of the OP amplifier A5. Further, the non-inverting input of the OP amplifier A5 is connected to the reference voltage line, and the reference voltage is applied. The analog switch S8 is a switch that opens and closes between both terminals of the capacitor Cc2 (that is, between the output and the inverting input of the OP amplifier A5), and operates in exactly the same manner as the analog switch S7.

Next, the OP amplifier A6 constitutes a difference circuit that amplifies and outputs the difference between the output of the OP amplifier A4 (hereinafter referred to as output VA) and the output of the OP amplifier A5 (hereinafter referred to as output VB).
The analog switches S10 and S13 and the OP amplifier A7 constitute a synchronous detection circuit. This synchronous detection circuit is a circuit that outputs a capacitance sensor output V1 (approach detection signal) from an output (hereinafter referred to as difference output V0) of an OP amplifier A6 (difference circuit). In this case, the differential output V0 changes, for example, as shown in the sixth stage (bottom stage) from the top in FIG. 3A, but the high voltage portion (that is, the switches S7 and S8 in the waveform of the differential output V0). The voltage when the differential output V0 is stabilized after the switches S2 and S4 are turned on is output to the controller (not shown) of the slide door 5 as the capacitance sensor output V1.
The analog switch S10 and the analog switch S13 operate in the same manner as the analog switch S6 and S5 (see FIG. 3A).
The controller determines that the approach of the object has been detected when the output V1 of the approach detection circuit 40 reaches a level exceeding a prescribed threshold value, for example.

In the proximity detection circuit 40 configured as described above, when the analog switches S1, S3, and S6 are on, the stray capacitances Ca, Cb, and Cs are short-circuited and the voltage between the terminals is zero. At this time, since the analog switches S7 and S8 are also turned on, the voltages between the terminals of the capacitors Cc1 and Cc2 are similarly zero, and the outputs VA and VB are both reference voltages. Therefore, at this time, the differential output V0 becomes zero.
However, when the analog switches S1 and S3, the analog switches S7 and S8, and the analog switch S6 are sequentially turned off, and the analog switch S5 and the analog switches S2 and S4 are sequentially turned on, the short circuit of the capacitors Cc1 and Cc2 is released. A reference voltage is applied to each electrode (A electrode, B electrode, and S electrode). Therefore, a voltage corresponding to the capacitance ratio between the capacitor Cc1 and the stray capacitance Ca is output as the output VA, and a voltage according to the capacitance ratio between the capacitor Cc2 and the stray capacitance Cb is output as the output VB. Therefore, as a result, a voltage corresponding to the capacitance difference (difference value) between the stray capacitance Ca and the stray capacitance Cb is output as the difference output V0, and the stable value of this voltage is output from the capacitance sensor by the synchronous detection circuit described above. It is output as V1 (approach detection signal).
In this case, if the stray capacitance Ca increases with respect to the capacitor Cc1 due to the approach of a human body or the like, the output VA decreases.

According to the object detection sensor of the present example described above, when an object having a high dielectric constant such as a human body approaches the detection side of the sensor body 10, the detection function as a capacitance sensor by the approach detection circuit 40 described above is used. This is detected with high responsiveness and high reliability. That is, when an object having a high dielectric constant such as a human body approaches the detection side, the capacitance sensor output V1 changes sensitively. Therefore, by comparing this signal voltage with a predetermined threshold value, highly sensitive detection can be performed. It becomes possible. In particular, in this example, since it is a differential equation that takes the difference between signals according to two detection electrodes (A electrode and B electrode), it is hardly affected by adverse effects such as temperature drift, and basically has reliability and responsiveness. High detection is possible.
In the object detection sensor of this example, even if the object has a low dielectric constant, if the piezo cable 11 that is a sensor head is deformed by contacting the sensor body 10, it is between the core wire 16 and the shield net 18. Therefore, the contact detection circuit 30 detects the contact of the object, and outputs a piezo sensor output (contact detection signal) exceeding a specified threshold value.

That is, the object detection sensor of this example has both a function as a contact sensor and a function as a high-performance non-contact sensor (capacitance sensor).
For this reason, by complementing the shortcomings of the sensor methods, it is possible to detect an object with high reliability and high responsiveness as much as possible. For example, in the case of an adverse condition such as a rainy state or a state immediately before full closure, the function of the approach detection circuit 30 (that is, the function of the capacitance sensor) is disabled or the sensitivity of the approach detection circuit 30 is increased. By setting it relatively low (threshold adjustment on the controller side may be used), malfunction of the capacitance sensor due to water etc. is prevented, while the object is reliably detected by the function of the contact sensor. And maintain reliability. Further, when it is not an adverse condition such as a rainy state, the function of the capacitance sensor is set to high sensitivity, and an object such as a human body having a high dielectric constant can be detected without contact and with high responsiveness. Even an object with a low dielectric constant can be detected with high reliability by at least the function of the contact sensor.

As described above, the object detection sensor of the present example is capable of detecting an object with high reliability and high responsiveness as much as possible, and the conductor constituting the contact sensor (in this case, the shield net 18 described above). Since it is a simple configuration that can also be used as the detection electrode (A electrode) of the capacitance sensor, the number of parts can be reduced compared to the case where a contact sensor and a capacitance sensor are simply provided separately, and in terms of cost and production. This is particularly advantageous in terms of safety and installation space.
In particular, in the case of this example, the productivity is high because of the simple configuration in which only two cable-like members (piezo cable 11 and cable-like electrode 12) are mainly stacked. Moreover, it is a main body structure in which the number of cable-shaped members (cable-shaped electrodes 12) is basically increased by one compared to the conventional structure having only one cable-shaped member (configuration of only a cable-shaped pressure sensitive switch). Therefore, the increase in the outer dimensions of the sensor body is relatively small. In addition, when it is not necessary to be a differential type capacitance sensor, the cable-like electrode 12 is not necessary, and the sensor main body fits in the same outer dimensions as the conventional one.

Further, according to the opening / closing body pinching detection device (car sliding door pinching detection device) of the present example, since the above-described object detection sensor is used, the reliability is as high as possible while having a simple configuration. It is possible to detect pinching with high responsiveness. For example, in the case of adverse conditions such as rain conditions or the state immediately before full closure described above, the malfunction of the capacitance sensor is disabled or the sensitivity is set to a relatively low level to prevent malfunctions (such as pinching). This prevents the sliding door from closing or reversing when it does not occur), and the contact sensor function reliably detects pinching and prevents reliability (sliding door pinching) Maintain the reliability of the function. In addition, when it is not an adverse condition such as a rainy condition, the function of the capacitance sensor is set to high sensitivity, and an object such as a human body having a high dielectric constant can be detected without contact and with high responsiveness. It is possible to significantly reduce the possibility of malfunctions such as falling by being pushed by the sliding door. Further, even an object with a low dielectric constant (for example, a baggage such as a dry cardboard) can be detected with high reliability by at least the function of the contact sensor and can be reliably prevented from being caught.

(Second embodiment)
Next, a second embodiment will be described.
In this example, a position range in which the object detection sensor including the sensor body 50 having the cable-like pressure-sensitive switch 51 may be sandwiched by the slide door 5 (opening / closing body) instead of the piezo cable 11 in the first embodiment. It is a pinching detection device that detects a human body or the like (object) that approaches the object.
FIG. 4 is a cross-sectional view showing a configuration of the sensor main body 50 of this example, and FIG. 5 is a diagram showing a detection circuit of the object detection sensor of this example. FIG. 6 is a timing chart for explaining the operation of the detection circuit.
Note that the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

The cable-like pressure sensitive switch 51 has the same configuration as the pressure sensitive switch 1 described with reference to FIG. That is, as shown in FIG. 4, it is a cable-like one in which four linear electrodes 53 to 56 are spirally attached to the inner surface of an insulating tube 52 while being separated from each other. Here, the linear electrodes 53 to 56 are obtained by coating the core wire with conductive rubber and have sufficient flexibility. For this reason, with the deformation of the tube 52 due to the contact of the object, the linear electrodes become conductive.
In this example, of the four linear electrodes 53 to 56, for example, the linear electrodes 53 and 55 constitute one electrode (conductor) of the cable-shaped pressure sensitive switch 51, and the remaining linear electrodes 54 and 56 constitute the other electrode (conductor) of the cable-like pressure sensitive switch 51. In this case, the linear electrodes 53 and 55 are connected to the inverting input of the OP amplifier A4 of the proximity detection circuit 40 via the analog switch S2, and the linear electrodes 54 and 56 are connected to the analog switch S2 and the analog switch S2 described later. The analog switch S11 is also connected to the inverting input of the OP amplifier A4 (see FIG. 5). For this reason, all the linear electrodes 53-56 become a structure which can function as an A electrode of an electrostatic capacitance sensor, and the electrode area of this A electrode is ensured as widely as possible.

Next, the detection circuit of this example will be described.
First, the approach detection circuit 40 has the same configuration as that of the first embodiment except that the linear electrode of the cable-like pressure sensitive switch 51 is an A electrode as described above. However, in this case, as shown in FIG. 6, the analog switches S1 and S3 are controlled to be in an ON state even at a contact detection timing described later.
On the other hand, as shown in FIG. 5, the contact detection circuit 60 includes an analog switch S12 and a resistor R2, which are sequentially connected in series between the power supply voltage line Vcc of the cable-like pressure sensitive switch 51 and the linear electrodes 54 and 56. The OP amplifier A1 whose downstream terminal of the resistor R2 is connected to the non-inverting input, the OP amplifier A2 whose upstream terminal of the resistor R2 is connected to the non-inverting input, the output of the OP amplifier A1, and the OP amplifier A2 An OP amplifier A3 that amplifies the output difference; an AND circuit AD1 that receives the output of the OP amplifier A3 as one input; an analog switch S14 that opens and closes between the other input of the AND circuit AD1 and the power supply voltage line Vcc; An analog switch S11 that opens and closes a line that short-circuits the linear electrodes 53 and 55 and the linear electrodes 54 and 56 is provided. The output of the AND circuit AD1 is input to the controller of the slide door 5 as a pressure sensitive switch output (contact detection signal).
In this case, the output of the OP amplifier A2 is divided by resistors R3 and R4 and input to the OP amplifier A3.

  Here, as shown in FIG. 6, the analog switch S <b> 11 is driven to be turned off at the contact detection time when the cable-like pressure sensitive switch 51 is detected and turned on at other times. In contrast to the analog switch S11, the analog switches S12 and S14 are driven so as to be turned on at the contact detection time and turned off at other times. In this case, the contact detection time is a period from the time when the analog switch S10 of the approach detection circuit 40 is turned on to the time when the analog switches S7 and S8 are turned on from the off state. Is the timing immediately after the approach detection timing (that is, the timing when the analog switch S10 is in the OFF state).

  According to the detection circuit configured as described above, since the analog switch S11 is on and the analog switch S12 is off at the approach detection time as the capacitance sensor, all linear shapes The electrodes 53 to 56 function as A electrodes that are disconnected from the power supply voltage line Vcc and connected to the approach detection circuit 40. Therefore, the excellent function as a capacitance sensor by the operation of the approach detection circuit 40 is exhibited as in the first embodiment.

At the time of contact detection as a pressure-sensitive contact sensor, the analog switch S11 is turned off and the analog switches S12 and S14 are turned on. Detected.
That is, when there is no contact between the objects and there is no conduction between one of the linear electrodes 53 and 55 and the other of the linear electrodes 54 and 56, no current flows through the resistor R2. The upstream terminal and the downstream terminal are at the same potential (both are the power supply voltage Vcc), and the difference between the output of the OP amplifier A1 and the output of the OP amplifier A2 becomes zero. As a result, the output of the OP amplifier A3 also becomes zero. The output (contact detection signal) of the AND circuit AD1 is also turned off.
However, when there is contact of an object and there is sufficient conduction between the linear electrodes 53 and 55 and the linear electrodes 54 and 56 (when the contact resistance is below a predetermined threshold). In the state where the upstream terminal of the resistor R2 is connected to the power supply voltage line Vcc by the analog switch S12, the downstream terminal of the resistor R2 is the cable-like pressure sensitive switch 51 (that is, the linear electrodes 53 and 55 and the linear electrode 54). , 56) and the analog switch S1, and the non-inverting input of the OP amplifier A1 is substantially at the ground level. Therefore, a sufficient current flows through the resistor R2 at this moment, and a voltage corresponding to the voltage drop of the resistor R2 is generated between the upstream terminal and the downstream terminal of the resistor R2. As a result, the output of the OP amplifier A3 Is turned on, the output of the AND circuit AD1 is also turned on, and the contact of the object is detected.

In the above detection operation, the resistances R3 and R4 are set to OP when the contact resistance of the cable-like pressure sensitive switch 51 (that is, the contact resistance between the linear electrodes 53 and 55 and the linear electrodes 54 and 56) decreases. This is for adjusting the above-described threshold value that determines whether the output of the amplifier A3 is turned on to detect contact.
The AND circuit AD1 prevents an erroneous contact detection signal from being output from the contact detection circuit 60 when it is not the contact detection time. That is, when it is not the contact detection time, the analog switch S14 is turned off and one input of the AND circuit AD1 is turned off, so that the output of the AND circuit AD1 is kept off regardless of the output of the OP amplifier A3. Is done.

  In the case of the charge transfer type capacitance sensor as in this example, the frequency at which each analog switch is turned on / off is normally set to a high speed of several KHz or more. For this reason, when the detection determination is performed by the output of the AND circuit AD1 at one contact detection timing, the determination time is limited to be considerably short. Therefore, the detection determination by the actual controller is performed, for example, when the output of the AND circuit AD1 is turned on at the contact detection timing for a predetermined number of times or more (that is, for a predetermined time or longer, for example, several msec or longer) It is also possible to determine that an object has been touched (when 51 corresponds to the on state). The same applies to the determination of approach detection and the determination of contact detection in the first embodiment.

  According to the second embodiment described above, the object detection sensor and the pinch detection device of the present invention using the pressure sensitive switch as a contact sensor are realized. In addition to the same effects as the first embodiment, the following There are inherent advantages. That is, since the main body configuration is basically a simple cable-like member (cable-like electrode 12) added to the same cable-like pressure-sensitive switch as that of the conventional product, effective use of the conventional product is expected. As a result, there are advantages in that the burden of designing and parts procurement is reduced, and the manufacturing can be performed at a lower cost. In addition, when it is not necessary to be a differential type capacitance sensor, the cable-like electrode 12 is unnecessary, and the sensor body fits in the same external dimensions as the conventional one and is basically substantially the same as the conventional product. Configuration may be sufficient.

The present invention is not limited to the above-described embodiments, and various modifications and applications are possible.
For example, the sensor head (the piezo cable 11 and the cable-shaped pressure sensitive switch 51) and the difference correction electrode (the cable-shaped electrode 12) do not necessarily have to be a cable having a circular cross section. As an example, a tape-shaped sensor head having a tape-shaped metal facing each other and a piezopolymer interposed therebetween, or a tape-shaped differential correction electrode may be used.
In the second embodiment, the cable-like pressure-sensitive switch 51 is exemplified as having four linear electrodes. However, when the electrode area as the detection electrode of the capacitance sensor is sufficient, FIG. As shown in FIG. 9, it may be a type having two linear electrodes.
Further, the configuration of the detection circuit is not limited to the above embodiment. The basic idea of the present invention is, for example, as shown in FIG. 7, a sensor body (for example, a piezo cable 11) basically having a configuration as a contact sensor, a contact sensor detection circuit (for example, a contact detection circuit 30), and the like. The detection circuit of the capacitance sensor (for example, the proximity detection circuit 40) using the conductor (for example, the shield mesh 18) of the sensor body as the detection electrode may be used. The detailed configuration is not particularly limited.

It is sectional drawing which shows the structure of the sensor main body of an object detection sensor. It is a figure which shows the detection circuit of an object detection sensor. It is a figure explaining operation | movement of an object detection sensor. It is sectional drawing which shows the structure of the sensor main body of an object detection sensor (2nd form example). It is a figure which shows the detection circuit of an object detection sensor (2nd form example). It is a figure explaining operation | movement of an object detection sensor (2nd form example). It is a figure explaining the basic composition of the present invention. It is a figure explaining the attachment state of a sensor main body. It is a figure which shows the conventional pressure sensitive switch.

Explanation of symbols

5 Sliding door (opening / closing body)
10, 50 Sensor body 11 Piezo cable (sensor head)
12 Cable electrode 13 Shield electrode 15 Elastic body 16 Core wire (conductor)
17 Piezopolymer 18 Shield net (conductor, detection electrode)
19 Protective skin 20 Core wire (detection electrode for differential correction)
30, 60 Contact detection circuit 40 Approach detection circuit 51 Cable-shaped pressure-sensitive switch (sensor head)
52 Tube 53-56 Linear electrode (conductor)

Claims (8)

A sensor body having a sensor head in which the resistance or voltage between the conductors forming a pair inside is deformed by contact with an object; and
A contact detection circuit that detects contact of an object with the sensor body and outputs a contact detection signal based on a change in resistance or voltage between the conductors;
An approach detection circuit that uses the conductor of the sensor head as a detection electrode, detects an approach of an object to the sensor body based on a change in stray capacitance formed by the detection electrode, and outputs an approach detection signal; An object detection sensor comprising: The sensor head is arranged such that a pair of deformable conductors is separated from each other in a natural state,
The contact detection circuit detects contact of an object with the sensor main body and outputs a contact detection signal based on a decrease in resistance between the conductors due to contact between the conductors. The object detection sensor according to claim 1. The sensor head is a cable-like one in which a plurality of linear electrodes are spirally attached to the inner surface of an insulating tube, and the linear electrodes function as the conductor,
The object detection sensor according to claim 2, wherein the approach detection circuit uses the linear electrode as the detection electrode. The sensor body includes a differential correction detection electrode disposed on the back side of the sensor head,
The approach detection circuit calculates a difference value between a value corresponding to the stray capacitance constituted by the detection electrode and a value corresponding to the stray capacitance constituted by the detection electrode for difference correction, and a change in the difference value The object detection sensor according to claim 1, wherein an approach detection signal is output by detecting the approach of the object to the sensor body based on the above. The sensor main body includes a cable-shaped differential correction detection electrode disposed along the back side of the sensor head,
The approach detection circuit calculates a difference value between a value corresponding to the stray capacitance constituted by the detection electrode and a value corresponding to the stray capacitance constituted by the detection electrode for difference correction, and based on the difference value The object detection sensor according to claim 3, wherein an approach detection signal is output by detecting the approach of the object to the sensor body. The object detection sensor according to claim 4, wherein an elastic body is interposed between the sensor head and the difference correction detection electrode in the sensor body. The object according to any one of claims 1 to 6, wherein a shield electrode for shielding is disposed on the sensor body so as to cover a non-detection range including at least the back side of the sensor body. Detection sensor. An object detection sensor according to any one of claims 1 to 7, wherein the sensor main body of the object detection sensor is attached to an opening / closing end of an opening / closing body, and an object in a position range that may be sandwiched between the opening / closing body is detected. An opening / closing body pinching detection device characterized by detecting.

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