JP2004198437A - Piezoelectric sensor and pinching-preventing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein the output of a conventional-type piezoelectric sensor is low, related to the piezoelectric sensor that detects contact of an object, and to a pinching-prevention equipment that detects pinching of the object, in an opening/closing part. <P>SOLUTION: By having on a piezoelectric sensor 8 formed with a protruding part 11, a recessed part 30, and a hole 31, and having an opposing member formed with a protruding part 35, a recessed part 37, and a hole 33, and using a mesh 39 and a coil spring 40, the area that receives a contact load is reduced, to increase a load per a unit area, and strain is increased due to a part tending to deform and a part not tending to deform, and which can make the output large. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a piezoelectric sensor that generates an output upon contact with an object, a load detection device for the piezoelectric sensor, and an anti-jamming device that arranges the piezoelectric sensor in an opening / closing unit such as a window, a door, or a shutter to detect and prevent jamming of an object. It is about.

A conventional piezoelectric sensor, a piezoelectric sensor load detecting device, and an anti-jamming device of this type (see, for example, Patent Document 1 or Patent Document 2) dispose a cable-shaped or film-shaped piezoelectric sensor in a window or a window frame to form a piezoelectric sensor. There has been a device that detects the pinching of an object by generating an output from a sensor. Since the piezoelectric sensor generates an electric charge proportional to the applied stress (strain), by taking out the electric charge as a polarization current, it is possible to detect a contact caused by pinching of an object.
JP-A-10-76843 JP-A-10-132669

  However, the conventional piezoelectric sensor load detecting device and anti-jamming device have the following problems.

  The piezoelectric sensor is electrically close to the capacitor C, and if a resistor R is connected in parallel to the output terminal, it becomes a high-pass filter having a cutoff frequency fc (= 1 / (2πCR)). On the other hand, an output signal due to contact with an object is generally a low-frequency signal of several tens of Hz or less, and if processed by a high-pass filter, the output level may be significantly reduced. Therefore, it is necessary to reduce the cutoff frequency fc by increasing the resistance R as much as possible. However, if the resistance is higher than 1 MΩ, it is expensive and handling such as noise countermeasures becomes difficult. For this reason, a practically high resistance must be employed, and the output level may be somewhat sacrificed. Further, the piezoelectric sensor has a very high output impedance and a low output voltage from the beginning, though it depends on the piezoelectric material and shape. Therefore, after the signal is received by an impedance conversion circuit such as an FET, the gain must be greatly increased by an amplifier circuit.

  After all, the conventional piezoelectric sensor, the piezoelectric sensor load detecting device, and the pinching prevention device have a problem that the output of the piezoelectric sensor is small.

  In order to solve the above-described problems, the piezoelectric sensor and the piezoelectric sensor load detecting device of the present invention reduce the area that receives a contact load from an object.

  According to the above invention, since the area receiving the contact load from the object is reduced, the load (pressure) per unit area of the contact portion increases, the displacement of the contact portion increases, the strain increases, and the generated electric charge increases. Increases, the polarization current increases, and the output of the piezoelectric sensor increases.

  Further, the piezoelectric sensor load detecting device according to the present invention has a reduced area that is displaced by receiving a contact load from an object.

  According to the above invention, since the area that is displaced by receiving a contact load from the object is reduced, there are portions that are displaced and portions that are not displaced, so that the strain in the piezoelectric sensor increases, the generated charge increases, and the polarization current increases. As a result, the output of the piezoelectric sensor increases.

  Also, the anti-jamming device of the present invention reduces the area that receives a contact load from an object, or reduces the area that is displaced by receiving a contact load from an object, by using a piezoelectric sensor and a piezoelectric sensor load detection device that abut the moving member. A piezoelectric sensor disposed in an opening / closing section composed of a member, and control means for detecting an object caught in the opening / closing section based on an output of the piezoelectric sensor and controlling opening / closing operation of the opening / closing section. Things.

  According to the invention, when the area where the piezoelectric sensor receives the contact load from the object is reduced, the load (pressure) per unit area of the contact portion increases, the displacement amount of the contact portion increases, and the strain is reduced. As a result, the generated charge increases, the polarization current increases, and the output of the piezoelectric sensor increases. Therefore, the output of the piezoelectric sensor is increased, and the accuracy of pinch detection can be improved. On the other hand, if the area of the piezoelectric sensor that is displaced by receiving a contact load from the object is reduced, there are parts that displace and parts that do not displace, so the strain in the piezoelectric sensor increases, the generated charge increases, and the polarization current increases. As a result, the output of the piezoelectric sensor increases, so that the accuracy of pinch detection can be improved.

  As described above, the piezoelectric sensor according to claim 1 of the present invention reduces the area where the piezoelectric sensor itself receives a contact load from an object, so that the load (pressure) per unit area of the contact portion increases, The displacement of the contact portion increases, the strain increases, the generated charge increases, the polarization current increases, and the output of the piezoelectric sensor increases.

  In addition, at least one convex portion, concave portion, or hole is provided on a surface that receives a contact load from the object. The projection of the piezoelectric sensor easily contacts the object, and the periphery of the projection hardly contacts the object. Conversely, the concave portion or the hole of the piezoelectric sensor hardly comes into contact with the object, and the periphery of the concave portion or the periphery of the hole easily comes into contact with the object. Therefore, the piezoelectric sensor has a portion that is likely to be in contact with the object and a portion that is not easily contacted, so that the area that receives the contact load from the object can be reduced. Therefore, there is an effect that the output of the piezoelectric sensor can be easily increased.

  According to a second aspect of the present invention, there is provided a piezoelectric sensor load detecting device in which an opposing member having at least one convex portion, concave portion, or hole is opposed to the piezoelectric sensor.

  First, when the opposing member is disposed on the object side when viewed from the piezoelectric sensor, the piezoelectric sensor at the position opposing the convex portion of the opposing member is easily pressed by the convex portion, and thus easily receives a load from the object. The piezoelectric sensors at the opposed positions are less likely to receive a load from the object. Conversely, the piezoelectric sensor at the position facing the concave portion or the hole of the opposing member is not pressed from the concave portion or the hole, so it is difficult to receive the load from the object, and the piezoelectric sensor at the position around the concave portion or around the hole is It becomes easy to receive the load from the object. Therefore, the piezoelectric sensor has a portion that is likely to receive the load from the object and a portion that is unlikely to receive the load from the object, so that the area receiving the contact load from the object can be reduced.

  On the other hand, when the opposing member is located on the opposite side of the object as viewed from the piezoelectric sensor, the piezoelectric sensor at the position opposing the convex portion of the opposing member is displaced even when receiving a load from the object because it is obstructed by the convex portion. Therefore, the piezoelectric sensor at a position facing the periphery of the convex portion is easily displaced. Conversely, the piezoelectric sensor at a position facing the concave portion or the hole of the opposing member is easily displaced when receiving a load from an object because the piezoelectric sensor is not hindered by the concave portion or the hole, and is located at a position facing the periphery of the concave portion or around the hole. Is difficult to be displaced. Therefore, the piezoelectric sensor has a portion that is easily displaced when receiving a load from the object and a portion that is hardly displaced when receiving a load from the object, and thus the area that is displaced by receiving the contact load from the object can be reduced. Therefore, in any case, there is an effect that the output of the piezoelectric sensor increases.

  In the piezoelectric sensor according to the third aspect of the present invention, the facing member has a mesh shape, and in the piezoelectric sensor according to the fourth aspect of the present invention, the facing member has a coil spring shape. Protrusions or depressions or holes can be formed. Therefore, similarly to the second aspect, the area where the piezoelectric sensor receives the contact load from the object can be reduced, and the area where the piezoelectric sensor receives the contact load from the object can be reduced, so that the output of the piezoelectric sensor can be easily increased. There is an effect that can be done.

  Further, in the piezoelectric sensor according to claim 5 of the present invention, since the piezoelectric sensor is disposed along the facing member having at least one convex or concave portion or hole, the piezoelectric sensor itself has at least one convex or concave portion. Alternatively, since the hole has the hole, the area receiving the contact load from the object can be reduced, and the area where the piezoelectric sensor is displaced by receiving the contact load from the object can be reduced. Therefore, there is an effect that the output of the piezoelectric sensor can be easily increased.

  Further, an anti-jamming device according to claim 6 of the present invention is an opening / closing unit configured by the piezoelectric sensor and the piezoelectric sensor load detecting device according to any one of claims 1 to 5 comprising a moving member and a contact member. And a control means for detecting the object being caught in the opening / closing section based on the output of the piezoelectric sensor and controlling the opening / closing operation of the opening / closing section.

  When the area where the piezoelectric sensor receives the contact load from the object is reduced, the load (pressure) per unit area of the contact portion increases, the displacement of the contact portion increases, the strain increases, and the generated charge increases. Increases, the polarization current increases, and the output of the piezoelectric sensor increases.

  On the other hand, when the load sensor reduces the area in which the piezoelectric sensor receives a contact load from an object and is displaced, there is a portion that is displaced and a portion that is not displaced. The polarization current increases, and the output of the piezoelectric sensor increases.

  Therefore, in any case, the output of the piezoelectric sensor is increased, so that there is an effect that the accuracy of the entrapment detection can be improved.

  In order to increase the output of the piezoelectric sensor, the piezoelectric sensor according to claim 1 of the present invention has at least one convex or concave portion or hole on the surface that receives the contact load from the object, so that the object receives the contact load from the object. In this case, the area receiving the light is reduced.

  Since the area of the piezoelectric sensor itself that receives the contact load from the object is reduced, the load (pressure) per unit area of the contact area increases, the displacement of the contact area increases, the strain increases, and the generated charge increases. As the polarization current increases, the output of the piezoelectric sensor increases.

  A piezoelectric sensor according to a second aspect of the present invention has at least one convex portion, concave portion, or hole on a surface that receives a contact load from an object in order to increase the output of the piezoelectric sensor.

  The projection of the piezoelectric sensor easily contacts the object, and the periphery of the projection hardly contacts the object. Conversely, the concave portion or the hole of the piezoelectric sensor hardly comes into contact with the object, and the periphery of the concave portion or the periphery of the hole easily contacts the object. Therefore, the piezoelectric sensor has a portion that is likely to be in contact with the object and a portion that is not easily contacted, so that the area that receives the contact load from the object can be reduced.

  Further, an opposing member having at least one convex portion, concave portion, or hole is made to oppose the piezoelectric sensor.

  When the opposing member is disposed on the object side when viewed from the piezoelectric sensor, the piezoelectric sensor at the position opposing the convex portion of the opposing member is pressed by the convex portion, so that it is likely to receive a load from the object, and the periphery of the convex portion The piezoelectric sensors at the opposed positions are less likely to receive a load from the object. Conversely, the piezoelectric sensor at the position facing the concave portion or the hole of the opposing member is not pressed from the concave portion or the hole, so it is difficult to receive the load from the object, and the piezoelectric sensor at the position around the concave portion or around the hole is It becomes easy to receive the load from the object. Therefore, the piezoelectric sensor has a portion that is likely to receive the load from the object and a portion that is unlikely to receive the load from the object, so that the area receiving the contact load from the object can be reduced. On the other hand, when the opposing member is located on the opposite side of the object as viewed from the piezoelectric sensor, the piezoelectric sensor at the position opposing the convex portion of the opposing member is displaced even when receiving a load from the object because it is obstructed by the convex portion. Therefore, the piezoelectric sensor at a position facing the periphery of the convex portion is easily displaced. Conversely, the piezoelectric sensor at a position facing the concave portion or the hole of the opposing member is easily displaced when receiving a load from an object because the piezoelectric sensor is not hindered by the concave portion or the hole, and is located at a position facing the periphery of the concave portion or around the hole. Is difficult to be displaced. Therefore, the piezoelectric sensor has a portion that is easily displaced when receiving a load from the object and a portion that is hardly displaced when receiving a load from the object, and thus the area that is displaced by receiving the contact load from the object can be reduced.

  In the piezoelectric sensor according to a third aspect of the present invention, the opposing member has a mesh shape.

  In a piezoelectric sensor according to a fourth aspect of the present invention, the opposed member has a coil spring shape.

  If the facing member has a mesh shape or a coil spring shape, a convex portion, a concave portion, or a hole portion can be easily formed on the surface facing the piezoelectric sensor, so that the area where the piezoelectric sensor receives a contact load from an object can be reduced, The area where the piezoelectric sensor is displaced by receiving a contact load from an object can be reduced.

  According to a fifth aspect of the present invention, in addition to the above, the piezoelectric sensor is provided along the facing member.

  When the piezoelectric sensor is disposed along the facing member having at least one convex portion, concave portion, or hole, the piezoelectric sensor itself has at least one convex portion, concave portion, or hole, and a contact load is applied from an object. The receiving area can be reduced, and the area where the piezoelectric sensor is displaced by receiving a contact load from an object can be reduced.

  According to a sixth aspect of the present invention, there is provided an anti-jamming device, comprising: a piezoelectric sensor provided in an opening / closing portion formed by a moving member and a contact member by the piezoelectric sensor according to any one of the first to fifth aspects. And control means for detecting the object being caught in the opening / closing section based on the output of the piezoelectric sensor and controlling the opening / closing operation of the opening / closing section.

  When the area where the piezoelectric sensor receives the contact load from the object is reduced, the load (pressure) per unit area of the contact portion increases, the displacement of the contact portion increases, the strain increases, and the generated charge increases. Increases, the polarization current increases, and the output of the piezoelectric sensor increases. On the other hand, when the load detection device reduces the area where the piezoelectric sensor receives a contact load from an object and is displaced, there are portions that are displaced and portions that are not displaced. The polarization current increases, and the output of the piezoelectric sensor increases. Therefore, in any case, the output of the piezoelectric sensor is increased, so that the accuracy of the entrapment detection can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Example 1)
FIG. 1 is an external view of an anti-jamming device according to a first embodiment of the present invention. This embodiment shows a case where the opening / closing section is applied to, for example, a power window for a vehicle. In the figure, 1 is a window glass as a moving member, 2 is a crank for moving up and down the window glass 1, and 3 is a driving means for driving the crank 2, which is, for example, a pulse-driven electric motor. Reference numeral 4 denotes, for example, an open / close position detecting unit that counts a pulse signal applied to the drive unit 3 and detects the open / close position of the window glass 1. A control unit 5 controls the driving unit 3 by outputting a pulse signal, for example. Reference numeral 6 denotes a window frame as an abutting member, and the window glass 1 and the window frame 6 form an opening / closing section 7. Numeral 8 denotes a piezoelectric sensor which is disposed along the window frame 6 so that the object contacts the piezoelectric sensor 8 when the object is sandwiched between the window glass 1 and the window frame 6, or that the sandwiched vibration is transmitted. Is used to detect entrapment.

  FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 2 shows a state in which the object 9 is sandwiched between the weather strip 10 attached to the window frame 6 due to the rising of the window glass 1, and at the same time, the object 9 also comes into contact with the piezoelectric sensor 8 attached to the window frame 6. ing. Since the piezoelectric sensor 8 has the convex portion 11 as a surface that receives a contact load with the object 9, the contact area with the object is much smaller than that without the convex portion 11. This is because the convex portion 11 easily contacts the object 9, but the periphery of the convex portion 11 hardly contacts the object 9.

  3A and 3B are views showing a state when the object 9 comes into contact with the piezoelectric sensor 8. FIG. 3A shows a case where the piezoelectric sensor 8 having a conventional shape is used, and FIG. This is a case where the piezoelectric sensor 8 having the portion 11 is used. In the conventional example and the present embodiment, assuming that the length X in the depth direction of the contact surface is equal and the lengths of the contact surface in the left-right direction are Yo and Ya (= Y1 + Y2 + Y3 + Y4 + Y5), the object 9 and the piezoelectric sensor 8 The contact areas are So = X × Yo and Sa = X × Ya, respectively, and the ratio of the contact areas can be expressed by So: Sa = Yo: Ya. 3A and 3B clearly show that Yo> Ya, so that the contact area also becomes So> Sa. Here, the piezoelectric sensor 8 has a configuration in which the piezoelectric material 12 has a pair of electrodes 13a and 13b, and in the case of FIG. 3B of the present embodiment, the protrusions 11 are formed by the shapes of the piezoelectric material 12 and the electrodes 13b to make contact. The area is reduced.

  In the present embodiment, the surface (convex portion 11) that receives the contact load from the object 9 is small, the load (ie, pressure) applied per unit area increases, and the displacement due to the load increases. As the displacement of the piezoelectric sensor 8 increases, the strain increases, the generated charge increases, the polarization current increases, and the output increases. Therefore, the piezoelectric sensor 8 according to the present embodiment generates a large output. be able to.

  The piezoelectric sensor 8 according to the present embodiment includes a flexible piezoelectric material 12 that is obtained by blending a sintered body of lead zirconate titanate as a piezoelectric ceramic with a rubber elastic organic base material and conducting polarization treatment on both surfaces thereof. A pair of electrodes 13a and 13b made of rubber are formed, and the piezoelectric sensor 8 as a whole has flexibility. If the piezoelectric material is formed by mixing the piezoelectric material with the rubber elastic body as in the present embodiment, the piezoelectric ceramic is excellent in heat resistance of depolarization, and therefore, the place where the temperature becomes high (for example, the place exposed to direct sunlight) ). For example, when it is installed in a place exposed to the outside world, such as an outdoor side of a window frame or a weather strip (10 in FIG. 2) or a side visor (shade for sunshade), the durability is good, and when detecting contact with an object. Reliability is improved. Also, since rubber elastic bodies are used for each of the piezoelectric material and the electrode, the workability is good and any shape can be accommodated.

  In this example, a sintered powder of lead zirconate titanate was used. However, it has high heat resistance and the orientation of the crystal structure due to polarization, that is, the property of generating a voltage with respect to a pressure load ( As long as it has piezo-electricity, for example, the same result as in the present embodiment can be obtained even when a sintered powder of lead titanate is used.

  When the use temperature is low, a conventional polyvinylidene fluoride film disclosed in JP-A-10-76843, JP-A-10-132669, or the like may be used.

  The electrode is not limited to conductive rubber, but may be a metal foil such as copper or aluminum, or a conductive paint.

  Note that the piezoelectric sensor 8 may be covered with an insulator, or the periphery thereof may be covered with a shield material.

  FIG. 4 is a configuration diagram of the piezoelectric sensor 8 before the arrangement according to the present embodiment. The piezoelectric sensor 8 is formed and arranged along the shape of the window frame 6. The contact detecting means 14 is formed integrally with the end of the piezoelectric sensor 8 and performs a circuit process to extract an output generated by the piezoelectric material 12 from a pair of electrodes and determine contact of an object. The lead 15 transmits and receives signals from the contact detecting means 14 and the control means 5.

  Although FIG. 4 shows a fixed shape having no irregularities in the longitudinal direction, irregularities may be formed in the longitudinal direction.

  FIG. 5 is an output characteristic diagram of the piezoelectric sensor of this embodiment. Assuming that an object (for example, a driver's finger) is sandwiched between the window glass 1 and the window frame 6 at time t0, the piezoelectric sensor generates an output as shown in FIG.

  FIG. 6 is a block diagram showing the circuit processing of this embodiment. The contact detecting means 14 for detecting a contact of an object based on the output signal from the piezoelectric sensor 8 converts the impedance of the output signal from the piezoelectric sensor 8 into an impedance, and filters the output signal from the impedance converter 16. It has a first filtering unit 17, a second filtering unit 18, and a contact determining unit 19 for determining contact of an object based on output signals from the two filtering units. Note that the contact detection means 14 may be entirely shielded by a metal case or the like in order to shield the signal processing circuit from electrical noise depending on the use environment, installation location, and the like.

  Although not shown, a resistor for detecting disconnection and short circuit between the electrodes 13a and 13b is connected to the tip of the piezoelectric sensor 8.

  FIG. 7 shows an example of a circuit diagram for detecting the disconnection / short circuit. In the drawing, Ps is a piezoelectric sensor 8, and r1 is a resistor for detecting disconnection, which is connected between the pair of electrodes 13a and 13b (p1 and p2 in the drawing) as described above. r1 is connected to the power supply Vd via another resistor r2. r3 and r4 are resistors for deriving a signal from the piezoelectric sensor 8, and Q1 is an FET for impedance conversion.

  Next, the operation and operation of the anti-jamming device will be described with reference to the drawings.

  In FIG. 1, for example, in a state where the windowpane 1 is below and the opening / closing unit 7 is open, the drive switch of the power window installed in the vehicle is operated to drive the drive means 3 and the windowpane 1 is closed. It is assumed that an object such as a part of a human body or a bag contacts the piezoelectric sensor 8 during the operation. A contact load is applied to the contact portion of the piezoelectric sensor 8 due to the contact of the object, and a displacement occurs to cause distortion in the piezoelectric material 12 itself. Therefore, a voltage as shown in FIG. The generated voltage level changes depending on the magnitude of the displacement at the time of contact and the sensitivity of the piezoelectric sensor 8 itself, that is, the piezoelectric constant of the piezoelectric material 12.

  Next, the signal generated from the piezoelectric sensor 8 is converted to a low impedance by the impedance conversion unit 16 of the contact detection unit 14. The impedance-converted signal is filtered by the first filtering unit 17 and the second filtering unit 18. FIG. 8 shows the filtering characteristics of the first filtering unit 17 and the second filtering unit 18. In the figure, the vertical axis represents power Pw and the horizontal axis represents frequency f. In the figure, when an object comes into contact, particularly when a part of a human body comes into contact, an output signal mainly about low frequency f1 is output from the piezoelectric sensor 8. Therefore, the filtering characteristic of the first filtering unit 17 is set to f1. Further, in the case of application to a power window of a vehicle as in the present embodiment, vibration of the vehicle itself centered on f2 (> f1) mainly due to vibrations caused by an engine, running, or the like is applied as a noise component to the piezoelectric sensor 8. The second filtering unit 18 sets the filtering characteristic to f2 in order to catch this component because the components are superimposed. Next, the contact determination unit 19 determines the contact of the object based on the filtered signals from the two filtering units.

  FIG. 9 illustrates the criterion. The horizontal axis is the output signal Vf2 from the second filtering unit 18, and the vertical axis is the output signal Vf1 from the first filtering unit 17. In the figure, when the value of Vf1 / Vf2 is large as in the region D1, it is determined that the object has touched, and when the value of Vf1 / Vf2 is small as in the region D2, it is determined that there is no contact.

  FIG. 10 is a judgment flowchart showing the procedure of the above judgment. When the SW of the power window is turned on in step 20, the drive means operates in step 21, Vf1 and Vf2 are calculated in step 22, and the ratio k between Vf1 and Vf2 is calculated in step 23. Next, in step 24, k is compared with a predetermined set value k0. If k> k0, it is determined in step 25 that there is contact with an object, and in step 26 the driving means is stopped. If k> k0 is not satisfied in step 24, it is determined that there is no contact in step 27, and the processing from step 22 is continued until the closing of the window is detected in step 28. The detection of the closing of the window is performed, for example, by detecting that the current value applied to the motor of the driving means at the time of closing the window becomes a certain value or more. In step 26, the driving means may be reversed to lower the window.

  Although two filtering units are provided in the above description, the number of filtering units is not limited to two, and the characteristics and number of the filtering units can be optimized according to an application example so as to detect pinching. In particular, if the output signal level at the time of contact with an object is much higher than the level of vibration noise of the vehicle due to the shape and arrangement method of the piezoelectric sensor 8, one filtering unit may be used. The unit may not be used. The value of k may be optimized in advance by experiments or the like in consideration of the vibration characteristics of the vehicle and the like.

  Further, as shown in FIG. 7, by applying a voltage between the electrodes via the resistor r1 and monitoring the output VO1, disconnection of the electrodes can be detected. That is, in FIG. 7, VO1 in the normal state is a divided voltage of r1, r2, and r3 with respect to the power supply voltage Vd. If the point p1 or the point p2 is equivalently opened when the electrode of the piezoelectric sensor 8 is disconnected, VO1 becomes the partial pressure value of r2 and r3. When the electrodes are short-circuited, p1 and p2 are equivalently short-circuited, so that VO1 becomes 0. As described above, an abnormality such as disconnection or short-circuit of the electrode of the piezoelectric sensor 8 can be detected based on the value of VO1, and reliability can be improved.

  With the above operation, the opening / closing operation of the opening / closing unit can be stopped when contact with the object is detected based on the output signal of the piezoelectric sensor, and the piezoelectric sensor converts distortion caused by contact with the object into an electric signal. Therefore, even if the piezoelectric sensor gets wet due to rain, car washing, or the like, it is possible to accurately detect the entrapment without erroneous detection. In addition, since the piezoelectric sensor does not have a contact such as a pressure-sensitive switch, it is possible to realize a durable anti-jamming device without poor contact or short circuit.

  If the piezoelectric sensor is disposed on the window frame side, that is, on the contact member, as in the present embodiment, the piezoelectric sensor does not move at the time of opening and closing, so that the holding of the lead wire or the like is easy.

  The piezoelectric sensor may be provided on the window glass side, that is, on the moving member side. In this case, there is an effect that the detection error and the detection delay hardly occur because the contact is surely made at the time of the pinching. Similarly, in the case of automobiles, the window is positioned lower than the window frame, and when an object is sandwiched, it is likely that the window frame comes into contact with the window frame earlier than the window frame. And it is more likely that the vehicle can be stopped before being pinched, and the safety is higher.

  Further, in the present embodiment, the contact detection means detects only a specific frequency component generated at the time of contact with an object out of the signals output from the piezoelectric sensor. The contact signal of the object can be detected by distinguishing the output signal of the piezoelectric sensor due to the vibration of the object from the output signal of the contact with the object, and the detection accuracy is improved.

  Also, if the output signal of whether or not the object has contacted is made valid only when the open / close position signal output from the open / close position detecting unit is within a predetermined set range, the open / close position exceeds the set range, and the normal When the opening / closing section is completely closed, even if a signal is output from the piezoelectric sensor and the contact detection means detects that an object is in contact, the detection signal is ignored and unnecessary opening can be prevented.

  In addition, the piezoelectric sensor has a resistor between the electrodes on the sensor tip side to detect disconnection or short circuit of the sensor, and detects a disconnection or short circuit of the electrode by applying a voltage between the electrodes via the resistor and monitoring Therefore, reliability can be improved.

  In the above embodiment, one piezoelectric sensor is provided. However, if two piezoelectric sensors are provided, for example, the following effects can be obtained.

  If one is installed in the opening / closing part for detecting pinching and the other is installed for detecting vehicle vibration, only the output due to vehicle vibration is offset by taking the difference between the two outputs. As a result, pinch detection accuracy is improved.

  In addition, by providing the movable member and the abutting member respectively and stopping the driving of the driving means only when both of them generate a pinching output, the accuracy of pinching prevention is improved. For example, if the driver's finger touches the window glass when the window glass starts to rise from the fully opened state, it does not lead to the pinching, so there is no need to originally stop the vehicle (if it stops, the switch must be pressed again). In such a case, it can be stopped only when it is really caught, without stopping.

(Example 2)
11 and 12 show a configuration of the piezoelectric sensor 8 according to the second embodiment of the present invention. FIG. 11 is an enlarged cross-sectional view, and FIG. 12 is a view from the side. The piezoelectric sensor 8 of the present embodiment is formed in a coaxial cable shape by disposing the piezoelectric material 12 between the inner layer electrode 13a and the outer layer electrode 13b and covering the periphery with a covering material 29. The covering material 29 has a concave portion 30, and the concave portion 30 is hardly in contact with the object, and is configured to contact the object only in a portion other than the concave portion 30. Therefore, the area that receives the contact load from the object can be reduced, so the load (pressure) per unit area of the contact area increases, the displacement of the contact area increases, the strain increases, the generated charge increases, and the polarization current increases. As a result, the output of the piezoelectric sensor increases.

  According to the present embodiment, since the piezoelectric sensor 8 has a cable shape, the surface is a curved surface, and there is a possibility that the area receiving a contact load with an object can be further reduced.

  Further, in the piezoelectric sensor 8 of the present embodiment, the outer layer electrode 13b can also serve as an electric shield layer.

  Although the concave portion 30 is shown in a circular shape in FIG. 12, the present invention is not limited to this, and the concave portion 30 may be formed like a groove continuously in the longitudinal direction or the circumferential direction.

  The covering material 29 may be integrated with the weather strip or the side visor. In this case, the number of parts and the assembly process can be reduced.

  Further, the covering material 29 may be mounted not only on the vehicle body but also on a weather strip or side visor.

(Example 3)
FIG. 13 shows a configuration of the piezoelectric sensor 8 according to the third embodiment of the present invention. The piezoelectric sensor 8 of the present embodiment has the hole 31, and the hole 31 is hardly in contact with the object, and is in contact with the object only in a portion other than the hole 31. Therefore, the area that receives the contact load from the object can be reduced, so the load (pressure) per unit area of the contact area increases, the displacement of the contact area increases, the strain increases, the generated charge increases, and the polarization current increases. As a result, the output of the piezoelectric sensor increases.

(Example 4)
FIG. 14 shows the configuration of the piezoelectric sensor 8 according to the fourth embodiment of the present invention. The piezoelectric sensor 8 is configured to be bent in an accordion shape (or bellows shape). When an object moves upward from below and comes into contact with the piezoelectric sensor 8, it can be said that the concave portion 30 and the convex portion 11 are evenly arranged. . In this case, the convex portion 11 easily contacts the object, and the concave portion 30 does not easily contact the object. Therefore, the area where the piezoelectric sensor 8 receives the contact load from the object can be reduced, so that the load (pressure) per unit area of the contact portion increases, the displacement of the contact portion increases, the strain increases, and the generated charge increases. The polarization current increases, and the output of the piezoelectric sensor increases.

  As described above, in the first to fourth embodiments, the example in which the area receiving the contact load from the object is reduced by the configuration of the piezoelectric sensor itself has been described. However, each embodiment is not limited to only the configuration. May be combined with each other or partially replaced.

  Regarding the anti-jamming device, the piezoelectric sensor may be mounted at a position where the object can be contacted when the object is nipped, so that the anti-jamming device may be mounted on the moving member or the abutting member, or other parts near the opening / closing unit ( For example, it may be mounted on a weather strip or a side visor.

(Example 5)
FIG. 15 shows a load detecting device for a piezoelectric sensor according to a fifth embodiment of the present invention. This embodiment is an example in which the area of receiving a contact load from an object is reduced by a method of disposing a piezoelectric sensor. The piezoelectric sensor 8 is provided on a weather strip 32 as an opposing member, and the weather strip 32 has a hole 33 formed on a surface facing the piezoelectric sensor 8. When an object coming from below the piezoelectric sensor 8 comes into contact with the weather strip 32, the piezoelectric sensor 8 at a position facing the hole 33 is not pushed from the hole 33, so it is difficult to receive a load from the object, and The load is applied only to the piezoelectric sensor 8 located at a position facing the portion without the hole 33. Therefore, the piezoelectric sensor 8 has a portion that is likely to receive the load from the object and a portion that is unlikely to receive the load from the object, so that the area that receives the contact load from the object can be reduced. As a result, the area receiving the contact load by the hole 33 is reduced, so that the load (pressure) per unit area of the contact part increases, the displacement of the contact part increases, the strain increases, and the The charge increases, the polarization current increases, and the output of the piezoelectric sensor 8 increases.

(Example 6)
FIG. 16 shows a piezoelectric sensor load detecting device according to a sixth embodiment of the present invention. In this embodiment, a convex portion is formed on the facing member. FIG. 16A shows an example in which the piezoelectric sensor 8 and the facing member 34 are separately configured, and FIG. In each of the examples mounted inside the strip 32, a projection 35 is formed on the surface facing the piezoelectric sensor 8. When an object coming from below the piezoelectric sensor 8 comes into contact with the opposing member 34 or the weather strip 32, the piezoelectric sensor 8 at a position facing the convex portion 35 is pressed by the convex portion 35, and thus easily receives a load from the object. The piezoelectric sensor 8 at a position facing the periphery of the projection 35 is less likely to receive a load from an object. Therefore, the piezoelectric sensor has a portion that is likely to receive the load from the object and a portion that is unlikely to receive the load from the object, so that the area receiving the contact load from the object can be reduced. As a result, the area receiving the contact load by the convex portion 35 is reduced, so that the load (pressure) per unit area of the contact portion increases, the displacement of the contact portion increases, the strain increases, and the The charge increases, the polarization current increases, and the output of the piezoelectric sensor 8 increases.

(Example 7)
FIG. 17 shows a piezoelectric sensor load detecting device according to a seventh embodiment of the present invention. The present embodiment is an example relating to an anti-jamming device for a power window of a vehicle, in which a flexible piezoelectric sensor 8 is disposed on a window glass 36 as a moving member. A concave portion 37 is formed at the tip of the window glass 36, and when an object comes into contact with the piezoelectric sensor 8 from above, the piezoelectric sensor 8 is bent and pushed until it contacts the tip of the window glass 36. When a load is further applied, the window glass 36 is considered to be an opposing member disposed on the side opposite to the object when viewed from the piezoelectric sensor. Therefore, the piezoelectric sensor 8 is easily displaced downward, and the piezoelectric sensor 8 at the position facing the periphery of the concave portion 37 is not easily displaced. Therefore, since the piezoelectric sensor 8 has a portion that is easily displaced and a portion that is hardly displaced when receiving a load from an object, the strain in the piezoelectric sensor 8 increases, the generated electric charge increases, and the polarization current increases. The output of the piezoelectric sensor 8 increases.

  In this embodiment, the window glass 36 also serves as the facing member, but may be constituted by another component.

(Example 8)
FIG. 18 shows a piezoelectric sensor load detecting device according to an eighth embodiment of the present invention. In this embodiment, an accordion-shaped opposing member 34 is provided on a support member 38, and a piezoelectric sensor 8 is disposed on the opposing member 34. An object coming from below hits the piezoelectric sensor 8. The opposing member 34 is disposed on the opposite side of the piezoelectric sensor 8 from the object, and has a convex portion 35 and a concave portion 37. In this case, the piezoelectric sensor 8 at the position facing the convex portion 35 is hardly displaced even when receiving a load from an object because the piezoelectric sensor 8 is obstructed by the convex portion 35, and the piezoelectric sensor 8 at the position facing the concave portion 37 is obstructed by the concave portion 37. Because it cannot be displaced, it becomes easy to be displaced if it receives a load from an object. Therefore, since the piezoelectric sensor 8 has a portion that is easily displaced and a portion that is hardly displaced when receiving a load from an object, the strain in the piezoelectric sensor 8 increases, the generated electric charge increases, and the polarization current increases. The output of the piezoelectric sensor 8 increases.

(Example 9)
FIG. 19 shows a piezoelectric sensor load detecting device according to a ninth embodiment of the present invention. In this embodiment, the piezoelectric sensor 8 is covered with the mesh 39, and the mesh 39 as the opposing member is disposed on the object side when viewed from the piezoelectric sensor 8. In this configuration, an object coming from below comes in contact with the mesh 39 and transmits a contact load to the piezoelectric sensor 8 via the convex portion 35 of the mesh 39. Since the area where the piezoelectric sensor 8 receives the contact load from the object is reduced by the mesh 39, the load (pressure) per unit area of the contact portion increases, the displacement amount of the contact portion increases, and the strain increases. As a result, the generated charge increases, the polarization current increases, and the output of the piezoelectric sensor 8 increases.

(Example 10)
FIG. 20 shows a piezoelectric sensor load detecting device according to a tenth embodiment of the present invention. In the present embodiment, the piezoelectric sensor 8 is supported via the coil spring 40, and the coil spring 40 as the opposing member is disposed on the opposite side of the piezoelectric sensor 8 from the object. When an object coming from below comes into contact with the piezoelectric sensor 8, the piezoelectric sensor 8 at a position facing the coil portion of the coil spring 40 is hardly displaced even when receiving a load, and the piezoelectric sensor 8 at a position facing the gap is displaced. It will be easier. Therefore, since the piezoelectric sensor 8 has a portion that is easily displaced and a portion that is hardly displaced when receiving a load from an object, the strain in the piezoelectric sensor 8 increases, the generated electric charge increases, and the polarization current increases. The output of the piezoelectric sensor 8 increases.

(Example 11)
FIG. 21 shows a load sensor for a piezoelectric sensor according to an eleventh embodiment of the present invention. In this embodiment, the piezoelectric sensor 8 is disposed along the facing member 34 having the convex portion 35 and the concave portion 37, and as a result, the piezoelectric sensor 8 itself has irregularities. In this embodiment, since the area where the piezoelectric sensor 8 receives the contact load from the object is reduced, the load (pressure) per unit area of the contact portion increases, and the displacement amount of the contact portion increases. The distortion increases, the generated charge increases, the polarization current increases, and the output of the piezoelectric sensor 8 increases.

  In addition, it is conceivable that the opposing member forms irregularities on the surface opposite to the object so that the piezoelectric sensor follows the object. In this case, the piezoelectric sensor at a position close to the support member (on the convex portion of the opposing member) is hindered by the support member and is not easily displaced, whereas the piezoelectric sensor at a position far from the support member (on the concave portion of the opposing member). Is not disturbed by the support member, so that it is easily displaced. Therefore, a portion that is displaced and a portion that is not displaced are generated, so that the strain in the piezoelectric sensor increases, the generated charge increases, the polarization current increases, and the output of the piezoelectric sensor increases.

(Example 12)
FIG. 22 is an operation block diagram of the anti-jamming device according to the twelfth embodiment of the present invention. FIG. 22 also shows a cross section of the piezoelectric sensor 8. In the present embodiment, the piezoelectric sensor 8 of the other embodiment is formed into a laminated film and replaced with the following configuration. Two piezoelectric materials 12a and 12b provided with electrodes 13c and 13d and 13e and 13f are laminated and molded, and a voltage signal of a specific frequency is applied to the electrodes 13e and 13f of one piezoelectric material 12b constituting the piezoelectric sensor 8. And a signal applying unit 41 for generating vibrations. The contact detecting means 14 calculates a pressure applied to the piezoelectric sensor 8 based on an output signal generated between the electrodes 13c and 13d of another piezoelectric material 12a by the vibrations. It is provided with a pressure calculation unit 42 and a contact determination unit 43 that determines contact of an object based on an output signal of the pressure calculation unit 42. The contact detection means 14 includes a first band-pass filter 44 having a center frequency of the frequency f3 generated by the signal applying section 41 and a second band-pass filter 45 having a center frequency of f1 in FIG. Since the piezoelectric sensor 8 of this embodiment is in the form of a film and has a small thickness even when laminated, the displacement can be increased and the output can be increased.

  The outside of the piezoelectric sensor 8 may be sealed with a protective layer such as PET or a metal film for electrical shielding.

  Next, the operation and operation will be described.

  In short, in other embodiments, the pinching is detected by the output of the piezoelectric sensor, whereas in the present embodiment, the pinching is detected by a change in the output of the piezoelectric sensor.

  In the piezoelectric sensor 8, the piezoelectric material 12b vibrates according to the voltage signal of the frequency f3 generated by the signal applying unit 41. Then, a piezoelectric electromotive force is generated in the piezoelectric material 12a according to the vibration. The generated output signal is filtered by the first band pass filter 44. At this time, the signal waveforms of the oscillation signal V3 of the signal applying unit 41 and the output V4 of the first bandpass filter 44 are as shown in FIGS. 23 (a) and 23 (b), respectively. 23 (a) and 23 (b), the vertical axis is V3 and V4, and the horizontal axis is time t. It is assumed that the object is in contact with the piezoelectric sensor 8 at time t1 and the pressure Pr1 is applied. In a state where the object is not in contact (t <t1), the amplitude of V4 is D40. When the object comes into contact at time t1 and the pressure Pr1 is applied to the piezoelectric sensor 8, the amplitude of V4 changes to D41. Here, there is a relationship between the amplitude D4 of V4 and the pressure Pr as shown in FIG. 24, and D4 has a characteristic of decreasing as the pressure Pr increases. Since this characteristic changes depending on the oscillation frequency f3, the shape of the piezoelectric materials 12a and 12b, and the like, it may be optimized in advance by experiments or the like according to the application. The pressure calculation unit 42 calculates Pr1 from D41 based on the relationship in FIG. Then, the contact determination unit 43 determines that an object has contacted if Pr1 is equal to or greater than a certain threshold value Pr0, and determines that there is no object contact if Pr1 is smaller than Pr0. If the contact of the object is detected as described above during the closing operation of the moving member such as the window glass, the closing operation is reversed to prevent the object from being pinched. In the present embodiment, the piezoelectric sensor is formed thin in the shape of a film to reduce the radius of curvature of the deformed portion, so that the amplitude D4 becomes large as a whole, and it becomes easy to see the change in Pr1. Can be.

  According to the above-described operation, for example, when vibration during traveling of the vehicle is applied to the piezoelectric sensor 8, if the piezoelectric sensor 8 is of a type that detects vibration or distortion as in the first embodiment, the piezoelectric sensor 8 due to traveling vibration In some cases, it is difficult to distinguish the output signal from the output signal of the piezoelectric sensor 8 due to the contact of the object, but the piezoelectric sensor 8 of the present embodiment outputs a signal corresponding to the contact pressure of the object, Since the contact pressure of the object is detected by the pressure calculation unit 42 and the contact is determined by the contact determination unit 43, the contact of the object can be detected with high accuracy even when the running vibration as described above is applied.

  Note that the contact determination unit 43 determines that an object has contacted if Pr1 is equal to or greater than a certain threshold value Pr0. However, the contact of the object may be determined based on a change rate or a variation pattern of Pr1.

  Further, as shown in FIG. 22, the contact detecting means 14 includes a second band-pass filter 45 having a center frequency of f1. May be configured to detect the contact of the object based on the output signal of. The operation of this configuration will be described below. FIG. 23C shows the signal waveform of the output V5 of the second bandpass filter 45. In the figure, the vertical axis is V5 and the horizontal axis is time t. When an object comes into contact with the piezoelectric sensor at time t1, the vibration of frequency f3 by the piezoelectric material 12a and the vibration near f1 lower than f3 due to the distortion due to the contact of the object are applied to the piezoelectric material 12a, and f3 is applied from the piezoelectric material 12a. And a signal having a frequency component in which f1 is superimposed is output. Based on this output signal, the pressure calculation unit 42 calculates the pressure Pr via the first band-pass filter 44 as described above, and the output V5 of the second band-pass filter 45 is, for example, as shown in FIG. A signal having an amplitude D5 appears at a proper frequency f1. Then, for example, when D5 is equal to or greater than a certain threshold value D50, the contact determination unit 43 determines that an external vibration such as a running vibration of a vehicle is applied to the piezoelectric sensor 8 and determines that the object contacts based on the value of Pr as described above. judge. When D5 is smaller than D50, the contact of the object is determined based on at least one of the change rate and the variation pattern of D5 and the value of Pr. Thus, the presence / absence of an external vibration is determined by the output signal of the piezoelectric sensor 8, and the contact determination threshold is switched according to the presence / absence of the external vibration to perform the contact determination. The detection accuracy is improved as compared to the case of detecting the contact of

  In addition, regarding the arrangement of the piezoelectric sensor in the anti-jamming device of the automobile, the piezoelectric sensor may be disposed on the vehicle body on the window frame side, a weather strip, a side visor, or the like, may be integrated, or may be disposed on the window glass side. In the case of the hard top type, it may be provided on the vehicle body side instead of the window frame.

  In the above-described embodiment, the anti-jamming device using the piezoelectric sensor in the power window for a vehicle is described. However, the anti-jamming device may be used not only for a window but also for a door such as a door or a sunroof, or used for a shutter. Good. Basically, the present invention can be applied to a device in which a gap between the moving member and the contact member changes, that is, a device in which a certain object may be sandwiched.

  In the case of a train door or an automatic door at the entrance, it is considered that two moving members are opposed to each other, but those included in the present invention by placing the other viewed from one moving member as a contact member It is.

  The configuration of each of the above embodiments is not a limited configuration, and can be partially replaced or combined with the configuration shown in another embodiment. You can choose. For example, the facing member may be on the object side when viewed from the piezoelectric sensor, or may be on the side opposite to the object. The piezoelectric sensor may be provided on the facing member or may be provided on another member. The protrusions, recesses, and holes are not limited to those, and can be easily replaced with each other or combined with each other.

FIG. 1 is an external view of a piezoelectric sensor load detection device and a pinch prevention device according to a first embodiment of the present invention. Sectional view of the same device taken along line AA. (A) Cross-sectional view showing the arrangement of a conventional piezoelectric sensor (b) External view showing the arrangement of a piezoelectric sensor according to the first embodiment of the present invention External configuration diagram of the piezoelectric sensor Characteristic diagram of the same piezoelectric sensor Block diagram of the anti-jamming device Circuit diagram for disconnection detection of the same device FIG. 4 is a characteristic diagram showing filtering characteristics of a first filtering unit and a second filtering unit of the device. Characteristic diagram showing determination criteria for determining contact of an object with the opening / closing part of the device Flow chart showing the operation of the device Sectional view of a piezoelectric sensor according to a second embodiment of the present invention. External configuration diagram of the piezoelectric sensor Configuration diagram of a piezoelectric sensor according to a third embodiment of the present invention Sectional view of a piezoelectric sensor according to a fourth embodiment of the present invention. Sectional drawing which shows arrangement | positioning structure of the piezoelectric sensor in Example 5 of this invention. (A) Cross-sectional view showing the arrangement of piezoelectric sensors in Embodiment 6 of the present invention (b) Cross-sectional view showing the arrangement of piezoelectric sensors in another embodiment Sectional drawing which shows arrangement | positioning structure of the piezoelectric sensor in Example 7 of this invention. Sectional drawing which shows arrangement | positioning structure of the piezoelectric sensor in Example 8 of this invention. Sectional drawing which shows arrangement | positioning structure of the piezoelectric sensor in Example 9 of this invention. Sectional drawing which shows arrangement | positioning structure of the piezoelectric sensor in Example 10 of this invention. Sectional drawing which shows the arrangement structure of the piezoelectric sensor in Example 11 of this invention. Operation block diagram of an anti-jamming device in embodiment 12 of the present invention (A) a waveform characteristic diagram of the oscillation signal V3 of the signal application section of the device; (b) a waveform characteristic diagram of the output V4 of the first bandpass filter; and (c) an output waveform of the output V5 of the second bandpass filter. Waveform characteristic diagram A characteristic diagram showing a relationship between the amplitude D4 of the output V4 of the first bandpass filter of the device and the pressure Pr.

Explanation of reference numerals

1 Window glass (moving member)
5 control means 6 window frame (contact member)
7 Opening / closing part 8 Piezoelectric sensor 9 Object 11 Convex part (surface receiving contact load)
30, 37 recess 31, 33 hole 32 weather strip (opposing member)
34 Opposing member 35 Convex part 36 Window glass (moving member, opposing member)
39 mesh (opposite member)
40 coil spring (opposite member)

Claims (6)

A piezoelectric sensor made of a flexible piezoelectric material, wherein at least one convex or concave portion or hole is provided on a surface which receives a contact load from an object in order to increase the output of the piezoelectric sensor. A piezoelectric sensor with a reduced area that receives a contact load from an object. A piezoelectric sensor made of a flexible piezoelectric material, wherein in order to increase the output of the piezoelectric sensor, a facing member having at least one convex or concave portion or hole is opposed to the piezoelectric sensor, and a contact is made from an object. Piezoelectric sensor with reduced load receiving area. What is claimed is: 1. A piezoelectric sensor comprising a flexible piezoelectric material, wherein an opposing member has a mesh shape in order to increase an output of said piezoelectric sensor, and an area receiving a contact load from an object is reduced. A piezoelectric sensor made of a flexible piezoelectric material, wherein an opposing member has a coil spring shape and a reduced area for receiving a contact load from an object so as to increase the output of the piezoelectric sensor. The piezoelectric sensor according to claim 1, wherein the piezoelectric sensor is arranged along the facing member. The piezoelectric sensor according to any one of claims 1 to 5, which is provided in an opening / closing unit including a moving member and a contact member, and sandwiching an object in the opening / closing unit based on an output of the piezoelectric sensor. And a control means for controlling the opening and closing operation of the opening / closing section.

Images