JP3719046B2 - Anti-pinch device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric sensor that generates an output by contact of an object, and a pinching prevention device that detects and prevents the object from being caught in an opening / closing part such as a window, door, or shutter using a piezoelectric sensor.
[0002]
[Prior art]
In this type of conventional piezoelectric sensor and pinch prevention device, as described in JP-A-10-76843 and JP-A-10-132669, a cable-shaped or film-shaped piezoelectric sensor is disposed in a window or a window frame. Some of them detect the pinching of an object by generating an output from a piezoelectric sensor. Since the piezoelectric sensor generates an electric charge proportional to the applied stress (strain), it is possible to detect contact due to the object being caught by taking it out as a polarization current.
[0003]
[Problems to be solved by the invention]
However, conventional piezoelectric sensors and pinching prevention devices have the following problems.
[0004]
The piezoelectric sensor is electrically close to the capacitor C, and if a resistor R is connected in parallel to the output end, it becomes a high-pass filter having a cutoff frequency fc (= 1 / (2πCR)).
On the other hand, the output signal due to the contact of the object is generally a low frequency signal of several tens of Hz or less, so that if the signal is processed by a high pass filter, the output level may be significantly reduced. Therefore, it is necessary to increase the resistance R as much as possible to lower the cut-off frequency fc. However, when the resistance is higher than 1 MΩ, it is expensive and difficult to handle noise countermeasures. For this reason, a practically high resistance must be employed, and the output level may be sacrificed somewhat. In addition, although the piezoelectric sensor depends on the piezoelectric material and shape, the output impedance is very high and the output voltage tends to be low originally. Therefore, after receiving by an impedance conversion circuit such as an FET, processing such as significantly increasing the gain must be performed by an amplifier circuit.
[0005]
After all, the conventional piezoelectric sensor and the anti-pinch device have a problem that the output is small.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the piezoelectric sensor and the pinching prevention device of the present invention include a piezoelectric sensor disposed in an opening / closing portion configured by a moving member and a contact member, and the opening / closing operation based on an output of the piezoelectric sensor. Control means for controlling the opening / closing operation of the opening / closing part by detecting the object sandwiched in the part, the piezoelectric sensor comprising electrodes formed on both surfaces of the piezoelectric material, an insulator covering the electrode, and the insulator Of the piezoelectric sensor of the portion having the piezoelectric material, which is disposed through a buffer material so that the piezoelectric material and the electrode are disposed at least in a portion that receives a load due to contact with the object. The thickness is made thinner than the thickness of the piezoelectric sensor in the portion that does not have the piezoelectric material, and the thickness of the piezoelectric material in the portion that receives the load due to the contact with the object is the pressure of the portion that does not receive the load due to the contact with the object. Is obtained is characterized in that thinner than the thickness of the wood.
[0007]
According to the above invention, when the radius of curvature of the deformed portion is small, the displacement with respect to the same load increases, the strain increases, the generated charge increases, the polarization current increases, and the output increases.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, there is provided a pinching prevention device comprising: a piezoelectric sensor disposed in an opening / closing portion composed of a moving member and a contact member; and an object being caught in the opening / closing portion based on an output of the piezoelectric sensor. The piezoelectric sensor comprises an electrode formed on both surfaces of the piezoelectric material, an insulator covering the electrode, and a shield member covering the insulator. The piezoelectric material and the electrode are disposed through a buffer material so that the piezoelectric material and the electrode are disposed at least in a portion that receives a load due to contact with the object, and the thickness of the piezoelectric sensor in the portion having the piezoelectric material is the thickness of the piezoelectric material. The thickness of the piezoelectric sensor in the part that does not have the thickness is made thinner, and the thickness of the piezoelectric material in the part that receives the load due to the contact with the object is made thinner than the thickness of the piezoelectric material in the part that does not receive the load due to the contact with the object. It is obtained by the features.
[0009]
Claims of the invention 2 The pinching prevention device according to the present invention includes a piezoelectric sensor disposed in an opening / closing portion constituted by a moving member and a contact member, and detects the object pinching in the opening / closing portion based on an output of the piezoelectric sensor. The piezoelectric sensor has an accordion shape to reduce the curvature radius of the deformed portion in order to increase the output.
[0010]
And since it is an accordion shape, it is easy to deform | transform, the curvature radius of a deformation | transformation site | part becomes small easily, and an output becomes large.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
(Example 1)
FIG. 1 shows an external view of a pinching prevention device according to Embodiment 1 of the present invention. This embodiment shows a case where the opening / closing portion 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 raising and lowering the window glass 1, and 3 is a driving means for driving the crank 2, for example, a pulse-driven electric motor. Reference numeral 4 denotes an open / close position detection unit that detects the open / close position of the window glass 1 by counting pulse signals applied to the driving means 3, for example. Reference numeral 5 denotes control means for controlling the drive means 3 by outputting a pulse signal, for example. Reference numeral 6 denotes a window frame as a contact member, and the window glass 1 and the window frame 6 form an opening / closing part 7. A piezoelectric sensor 8 is disposed along the window frame 6. When an object is sandwiched between the window glass 1 and the window frame 6, the object contacts the piezoelectric sensor 8, or the sandwiched vibration is transmitted. Thus, the pinching is detected.
[0013]
FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 2 shows a state in which the object 9 is sandwiched between the window glass 1 and the window frame 6, and the piezoelectric sensor 8 disposed on the window frame 6 and the object 9 are in contact with each other through the cushioning material 10. . The piezoelectric sensor 8 has a shape in which the thickness of the central portion at the lower end (contact portion 11 with the object 9) is thinner than other portions.
[0014]
FIG. 3 is a cross-sectional configuration diagram of a main part of the piezoelectric sensor 8 and shows a difference in deformation due to thickness. FIG. 3A shows a case where the thick piezoelectric sensor 8 is used, and the curvature radius of the deformed portion can be expressed as R11 and R12. FIG. 3B shows the case where the piezoelectric sensor 8 of this embodiment having a small thickness is used, and the curvature radii of the deformed portions can be expressed as R21 and R22. When the same contact load 12 is applied, the smaller the thickness is, the easier it is to bend, so the radius of curvature is small (R21 <R11, R22 <R12). If the displacement amounts are L1 and L2, respectively, L2> L1 is large. . As the displacement of the piezoelectric sensor 8 increases, the strain increases, the generated charge increases, the polarization current increases, and the output increases. In this embodiment, by reducing the thickness of the contact portion 11 of the piezoelectric sensor 8, the radius of curvature of the deformed portion caused by the contact of the object is reduced, the displacement is increased, and the output is increased.
[0015]
FIG. 4 is a cross-sectional configuration diagram of a principal part showing in detail the piezoelectric sensor 8 of the present embodiment. The piezoelectric sensor 8 is a pair of conductive rubbers formed on both surfaces of a flexible piezoelectric material 13 obtained by blending a sintered elastomer of lead zirconate titanate as a piezoelectric ceramic with a rubber elastic organic base material. The electrode 14 is formed. These are covered with an insulator 15 made of a rubber elastic body, and the periphery thereof is covered with a shield 16 made of conductive rubber. Therefore, the piezoelectric sensor 8 has flexibility as a whole.
[0016]
In the piezoelectric sensor 8 according to the present embodiment, the surface of the piezoelectric material 13 is perpendicular to the direction of receiving a contact load at the same time as reducing the radius of curvature by reducing the portion (contact portion 11) where the object is supposed to contact. It is configured to be. With this configuration, the contact of the object is most efficiently transmitted to the piezoelectric material 13 and the maximum strain can be generated.
[0017]
Further, in this embodiment, the piezoelectric sensor 8 becomes thicker as the distance from the contact portion 11 increases. This is because the displacement of the portion without the piezoelectric material 13 is less likely to occur. By thickening the portion without the piezoelectric material 13 to make it difficult to bend, most of the contact load received from the object is changed in the piezoelectric material 13.
Can be converted to a position.
[0018]
Alternatively, the entire piezoelectric sensor 8 may be configured to have the same thickness, and may be held while reinforcing the end with another member.
[0019]
In addition, you may make it the structure which extended the piezoelectric material 13 and the electrode 14 not only to the vicinity of the contact site | part 11, but to the end. If both the piezoelectric material 13 and the electrode 14 are flexible as in this embodiment, they can be curved and arranged. In this case, it is also conceivable to decrease the thickness of the piezoelectric material 13 itself only at the contact portion and increase it at other portions.
[0020]
FIG. 5 is a configuration diagram of the piezoelectric sensor 8 before the arrangement of the present embodiment. A piezoelectric sensor 8 is molded and disposed along the shape of the window frame 6. The contact detection means 17 is configured integrally with the end of the piezoelectric sensor 8 and performs circuit processing to take out the output generated by the piezoelectric material 13 from the pair of electrodes 14 and determine the contact of the object. The lead wire 18 exchanges signals between the contact detection means 17 and the control means 5.
[0021]
FIG. 6 is an output characteristic diagram of the piezoelectric sensor of this embodiment. If 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.
[0022]
FIG. 7 is a block diagram showing the circuit processing of this embodiment. A contact detection unit 17 that detects contact of an object based on an output signal from the piezoelectric sensor 8 filters an output signal from the impedance conversion unit 19 that converts the impedance of the output signal from the piezoelectric sensor 8 and the impedance conversion unit 19. The first filtering unit 20 and the second filtering unit 21, and a contact determination unit 22 that determines contact of an object based on output signals from the two filtering units. The contact detection means 17 shields the signal processing circuit from electrical noise according to the usage environment, installation location, etc., so that the whole may be electrically shielded with a metal case or the like.
[0023]
Although not shown, a resistor for detecting disconnection / short circuit between the electrodes 14 is connected to the tip of the piezoelectric sensor 8.
[0024]
FIG. 8 shows an example of a circuit diagram for detecting the disconnection / short circuit. In the figure, Ps is the piezoelectric sensor 8, and r1 is a resistor for detecting disconnection, and is connected between the pair of electrodes 14 (p1 and p2 in the figure) as described above. r1 is connected to the power source Vd through 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.
[0025]
Next, the operation and action of the pinching prevention device will be described with reference to the drawings.
[0026]
In FIG. 1, for example, in a state where the window glass 1 is below and the opening / closing part 7 is opened, the drive switch of the power window installed in the vehicle is operated to operate the driving means 3 to close the window glass 1. It is assumed that an object such as a part of a human body or a heel contacts the piezoelectric sensor 8 during the process. As shown in FIG. 3B, contact load 12 is applied to piezoelectric sensor 8 due to the contact of the object, and displacement L2 is generated to cause distortion in piezoelectric material 13 itself. Therefore, a voltage as shown in FIG. appear. The generated voltage level varies depending on the magnitude of displacement at the time of contact and the sensitivity of the piezoelectric sensor 8 itself, that is, the piezoelectric constant of the piezoelectric material 13.
[0027]
Next, the signal generated from the piezoelectric sensor 8 is converted to a low impedance by the impedance converter 19 of the contact detector 17. The impedance-converted signal is filtered by the first filtering unit 20 and the second filtering unit 21. FIG. 9 shows the filtering characteristics of the first filtering unit 20 and the second filtering unit 21. In the figure, the vertical axis represents power Pw, and the horizontal axis represents frequency f. In the figure, when the object touches, particularly when a part of the human body touches, an output signal mainly centering on the low frequency f1 is output from the piezoelectric sensor 8. Therefore, the filtering characteristic of the first filtering unit 20 is set to f1. Further, in the case of application to the power window of the vehicle as in the present embodiment, the vibration of the vehicle itself centered on f2 (> f1) mainly due to the vibration caused by the engine or traveling, etc. is applied to the piezoelectric sensor 8 as a noise component. In order to superimpose, the second filtering unit 21 captures this component, and the filtering characteristic is set to f2. Next, the contact determination unit 22 determines the contact of the object based on the filtered signals from the two filtering units.
[0028]
FIG. 10 illustrates the determination criteria. The horizontal axis represents the output signal Vf2 from the second filtering unit 21, and the vertical axis represents the output signal Vf1 from the first filtering unit 20. In the figure, when the value of Vf1 / Vf2 is large as in the region D1, it is determined that the object is in contact, and when the value of Vf1 / Vf2 is small as in the region D2, it is determined that there is no contact.
[0029]
FIG. 11 is a determination flowchart showing the above-described determination procedure. When the SW of the power window is turned on in step 23, the driving means is operated in step 24, Vf1 and Vf2 are calculated in step 25, and the ratio k of Vf1 and Vf2 is calculated in step 26. Next, in step 27, k is compared with a predetermined set value k0. If k> k0, it is determined in step 28 that there is an object contact, and in step 29, the driving means is stopped. If it is determined in step 27 that k> k0 is not satisfied, it is determined in step 30 that there is no contact, and the processing in and after step 25 is continued until it is detected in step 31 that the window is closed. The detection of the closing of the window is performed, for example, by detecting that the value of the current applied to the motor of the driving means when the window is closed is greater than a certain value. In step 29, the drive means may be reversed to lower the window.
[0030]
In the above description, two filtering units are provided. However, the number of filtering units is not limited to two, and it is possible to optimize the characteristics and number of filtering units according to application examples so as to detect pinching. In particular, by reducing the radius of curvature of the deformed portion of the piezoelectric sensor 8, if the output signal level when the object comes into contact is much higher than the level of vibration noise of the vehicle, one filtering section may be used. In some cases, the filtering section may not be used. In addition, the value of k may be optimized by experiments in advance in consideration of the vibration characteristics of the vehicle.
[0031]
Further, as shown in FIG. 8, disconnection of the electrode can be detected by applying a voltage between the electrodes via the resistor r <b> 1 and monitoring the output VO <b> 1. That is, in FIG. 8, VO1 at normal time is a divided voltage value 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 a partial pressure value of r2 and r3. When the electrodes are short-circuited, equivalently, p1 and p2 are short-circuited, so V1 becomes zero. Thus, abnormality such as disconnection or short-circuit of the electrode of the piezoelectric sensor 8 can be detected based on the value of V1, and the reliability can be improved.
[0032]
With the above action, the opening / closing operation of the opening / closing part can be stopped when the contact of the object is detected based on the output signal of the piezoelectric sensor, and the piezoelectric sensor converts the distortion caused by the contact with the object into an electrical signal. Therefore, even if the piezoelectric sensor gets wet due to rain, car washing or the like, it is possible to detect pinching with high accuracy without erroneous detection. In addition, since the piezoelectric sensor does not have a contact point like a pressure-sensitive switch, it is possible to realize a pinching prevention device that has no contact failure or short circuit and has high durability.
[0033]
If the piezoelectric sensor is disposed on the window frame side, that is, the contact member as in this embodiment, the lead wire can be easily held because it does not move during opening and closing.
[0034]
The piezoelectric sensor may be disposed on the window glass side, that is, on the moving member side. In this case, there is no doubt that detection mistakes and detection delays are unlikely to occur because the contact is definitely made during the pinching. Similarly, in the case of an automobile, the window is lower in position than the window frame, and when objects are caught, it is considered that the window glass often comes in contact with the window glass first, so that only the window glass side contacts. Can be detected early, and it is highly possible that the vehicle can be stopped before being caught.
[0035]
In this embodiment, since the contact detection means detects only a specific frequency component generated when the object is in contact with the signal output from the piezoelectric sensor, for example, other than the object contact such as vibration due to the opening / closing operation of the opening / closing part or external vibration. It is possible to detect the contact of the object by distinguishing the output signal of the piezoelectric sensor due to the vibration and the output signal due to the contact of the object, and the detection accuracy is improved.
[0036]
In addition, if the output signal indicating whether or not an object has contacted is made valid only when the open / close position signal output from the open / close position detection unit is within a predetermined set range, the open / close position will normally exceed the set range. When the opening / closing part is closed, even if a signal is output from the piezoelectric sensor and the contact detection means detects that there is contact with an object, the detection signal can be ignored to prevent unnecessary opening.
[0037]
In addition, the piezoelectric sensor is equipped with a resistor for detecting the disconnection or short circuit of the sensor between the electrodes on the tip side of the sensor. By monitoring the voltage applied between the electrodes via the resistor, the disconnection or the short circuit of the electrode is detected. Therefore, reliability can be improved.
[0038]
In the above embodiment, one piezoelectric sensor is provided. However, if two piezoelectric sensors are provided, for example, the following effects can be obtained.
[0039]
First, if one is placed in the opening and closing part for detecting pinching and the other is placed for detecting vibration of the vehicle, only the output due to the vibration of the vehicle is canceled by taking the difference between the two outputs. This improves the pinching detection accuracy.
[0040]
Further, if the driving means is stopped only when both the moving member side and the abutting member side are disposed and both of them generate a pinching output, the pinching prevention accuracy is improved. For example, when the driver's finger touches when the window glass starts to rise from the fully open state, it is not necessary to stop it because it is not pinched (the switch must be pressed again when it stops). In such a case, it can be stopped only when it is really caught without being stopped.
[0041]
Further, as in this embodiment, if the piezoelectric material is formed by mixing a piezoelectric elastic with a rubber elastic body, the piezoelectric ceramic is excellent in heat resistance against depolarization, so that it is exposed to high temperatures (for example, exposed to direct sunlight). Place). For example, it is durable even when placed in places exposed to the outside, such as the outside of a window frame or weather strip (32 in FIG. 2) or side visor (shade for sunshade). Reliability is improved. In addition, since a rubber elastic body is used for each of the piezoelectric material and the electrode, the workability is good and it can correspond to any shape.
[0042]
Here, the piezoelectric material of this example (organic base material is chlorinated polyethylene, piezoelectric ceramic is a sintered powder of lead zirconate titanate), JP-A-10-76843, JP-A-10-132669, etc. In order to compare the conventional polyvinylidene fluoride (PVDF) shown in Fig. 2, it is molded into a size of about 2 tatami mats and placed on the floor, and the temperature is adjusted so that the temperature of the piezoelectric material becomes 100 ° C with a heating element. We measured and compared the voltage generated when a person entered the floor every hour. The weight of the subject at this time was 63 kg, and the voltage generated at the time of entering the floor in the present Example before the heat generation and the conventional product was designed to be 200 mV. The result is shown in FIG. The elapsed time is taken on the horizontal axis, and the generated voltage is taken on the vertical axis. The generated voltage a of the piezoelectric material of this example has almost no change with time, but the generated voltage b of the conventional piezoelectric material gradually increases. The voltage will decrease. In other words, the sensitivity of the piezoelectric material of this example can be stably maintained for a longer time than the conventional piezoelectric material.
[0043]
This is because a conventional polyvinylidene fluoride film is used, and if it is left for a long time at a high temperature of 100 ° C., the molecular crystal of polyvinylidene fluoride that has been oriented in the direction of voltage generation is disturbed. It seems that the structure changes and the generated voltage gradually decreases. On the other hand, since the heat resistance of the lead zirconate titanate sintered powder of this example is 300 ° C. to 350 ° C., the polarized crystal structure does not change even when left in 100 ° C., and the sensitivity is high. It is thought that it can be maintained stably.
[0044]
In this example, sintered powder of lead zirconate titanate was used, but the heat resistance is high, and the orientation of the crystal structure by polarization, that is, the property of generating a voltage against pressure load ( As long as it has a piezo property, for example, a lead titanate sintered powder can be used to obtain the same result as in this example.
[0045]
When the operating temperature is low, a polyvinylidene fluoride film may be used as in the conventional case.
[0046]
The electrode is not limited to conductive rubber, but may be a metal foil such as copper or aluminum or a conductive paint. However, it is desirable that the electrode is thinner in order to provide flexibility.
[0047]
(Example 2)
13 to 15 are configuration diagrams of the piezoelectric sensor according to the second embodiment of the present invention. In FIG. 13, the piezoelectric sensor 8 has a cut portion 33 and forms a thin portion 34. Both ends of the piezoelectric sensor 8 are fixed to the rigid body 35, but there is a gap 36 in the central portion of the rigid body 35 so that the central portion of the piezoelectric sensor 8 is not prevented from being displaced upward. FIG. 14A shows a cross-sectional configuration diagram of the main part when the conventional piezoelectric sensor 8 is used, and FIG. The radius of curvature of the deformed portion of this embodiment can be expressed as R31 and R32. When the same contact load 12 is applied, since the thin portion 34 is easily bent, the radius of curvature as a whole becomes small (R31 <R11, R32 <R12), and when the displacement amount is L3, L3> L1. As the displacement of the piezoelectric sensor 8 increases, the strain increases, the generated charge increases, the polarization current increases, and the output increases. In the present embodiment, since the piezoelectric sensor 8 has the thin portion 34 locally, the radius of curvature of the deformed portion caused by the contact of the object is reduced, the displacement is increased, and the output is increased.
[0048]
In this embodiment, since the gap 36 is provided at the location where the piezoelectric sensor 8 is disposed, the output can be further increased without hindering upward displacement.
[0049]
FIG. 15 is a perspective view showing an embodiment of the piezoelectric sensor 8. FIG. 15A shows the piezoelectric sensor 8 having a caterpillar shape, and a locally thin portion 34 is formed by the notch 33 in the depth direction of FIG. In this embodiment, since the radius of curvature in the left-right direction is particularly small during deformation, not only objects with a very small area, but also objects with long shapes in the depth direction (such as fingers and arms in the case of an anti-pinch device) However, the output can be increased.
[0050]
FIG. 15B shows another embodiment, in which the cut portion 33 is configured in the depth direction and the width direction to form a thin portion 34. In this embodiment, since the radius of curvature decreases in the left-right direction and the front-rear direction at the time of deformation, the output can be increased for objects of any shape.
[0051]
(Example 3)
FIG. 16 shows a configuration diagram of the piezoelectric sensor according to the third embodiment of the present invention. The piezoelectric sensor 8 is provided with notches 33 on the lower side as well as the upper side to form a thin portion 34. According to the piezoelectric sensor 8 of the present embodiment, since the cut portion 33 is also on the contact surface side with the object, the contact area with the object is reduced. When the load of the same magnitude is received by contact with an object, the smaller the contact area, the larger the load (pressure) per unit area, so that the displacement is further increased and the output can be further increased.
[0052]
In the present embodiment, the upper cut portion 33 and the lower cut portion 33 are arranged to face the thin portion 34, but the present invention is not limited to this.
[0053]
(Example 4)
17 and 18 are configuration diagrams of the piezoelectric sensor 8 according to the fourth embodiment of the present invention. FIG. 17 shows a cross section and an arrangement configuration of the main part of the piezoelectric sensor 8, and the piezoelectric sensor 8 has a hole 37 and is arranged on the rigid body 35 via the buffer material 10. Since the piezoelectric sensor 8 has improved flexibility due to the hole 37, the radius of curvature of the deformed portion due to contact with the object is smaller than when there is no hole.
Therefore, the displacement can be increased to increase the output.
[0054]
In the present embodiment, the piezoelectric sensor 8 is disposed on the buffer material 10, but the buffer material 10 has an effect of absorbing the impact, so that the reliability of the strength of the piezoelectric sensor 8 can be improved.
[0055]
FIG. 18 is a perspective view showing an embodiment of the piezoelectric sensor 8. 18A shows the piezoelectric sensor 8 in a lattice shape, and the hole 37 has a square shape. FIG. 18B shows the piezoelectric sensor 8 in which a circular hole 37 is formed in a punching shape. In any case, the size of the hole 37 is smaller than that of the contacting object so that the object does not enter the hole 37.
[0056]
If the piezoelectric sensor 8 is covered with another member having no hole or a small hole between the piezoelectric sensor 8 and the object, the hole 37 can be enlarged.
[0057]
The buffer material and another member having no hole or a small hole may be integrally formed to enclose the piezoelectric sensor 8, or the piezoelectric sensor 8 may be configured inside the buffer material. Further, the weather strip 32 and the side visor (not shown) of FIG. In this case, the number of parts and the assembly process can be reduced.
[0058]
(Example 5)
FIG. 19 is a cross-sectional configuration diagram of the piezoelectric sensor 8 according to the fifth embodiment of the present invention. The piezoelectric sensor 8 of this embodiment has an accordion shape (bellows shape) folded several times. FIG. 19A shows a state before contact with an object, and FIG. 19B shows a state after contact with the object. The radius of curvature of the deformed portion of the piezoelectric sensor 8 of this embodiment can be expressed as R41 and R42 as a whole. When the same contact load 12 is applied, the accordion shape easily expands and contracts, so that the curvature radii R41 and R42 of the deformed portion as a whole become small (R41 <R11, R42 <R12), and the displacement is L4> L1. And get bigger. As the displacement of the piezoelectric sensor 8 increases, the strain increases, the generated charge increases, the polarization current increases, and the output increases. In this embodiment, the accordion shape of the piezoelectric sensor 8 reduces the radius of curvature of the deformed portion caused by the contact of the object, increases the displacement, and increases the output.
[0059]
According to the present embodiment, the piezoelectric sensor 8 has not only a vertical direction but also a horizontal direction stretchability. The piezoelectric sensor 8 can be arranged freely while being pulled, arranged while being compressed, or curved. The degree is extremely high.
[0060]
(Example 6)
FIG. 20 shows an arrangement configuration of the piezoelectric sensor 8 according to the sixth embodiment of the present invention. The piezoelectric sensor 8 of the present embodiment is configured in a hollow shape, and the gap 36 is covered with the piezoelectric sensor 8. According to this embodiment, even if the piezoelectric sensor 8 is directly disposed on the rigid body 35, the hollow shape having the gap 36 therein.
Therefore, the flexibility is maintained, the radii of curvature R51 and R52 of the deformed part due to contact with the object can be reduced, the displacement L5 can be increased, and the output can be increased.
[0061]
(Example 7)
21 and 22 show a seventh embodiment of the present invention. FIG. 21 is a configuration diagram in which the piezoelectric sensor 8 is mounted on the window glass 1 as a pinching prevention device, and FIG. 22 is an enlarged cross-sectional view of the piezoelectric sensor 8 of FIG. The piezoelectric sensor 8 of this embodiment is configured in a coaxial cable shape in which the piezoelectric material 13 is disposed between the inner layer electrode 14a and the outer layer electrode 14b, and in a hollow shape having a gap 36 in the center.
[0062]
Furthermore, in this embodiment, the piezoelectric sensor 8 is fixed to the window glass 1 while being covered with a flexible covering material 38 such as rubber. In this embodiment, the contact load 12 is downward, and the covering material is This is transmitted to the piezoelectric sensor 8 via 38. Since the piezoelectric sensor 8 is hollow, the flexibility is improved, the radius of curvature of the deformed portion due to contact with the object is reduced, the amount of displacement is increased, and the output can be increased.
[0063]
In the piezoelectric sensor 8 of the present embodiment, the outer layer electrode 14b can also serve as an electrical shield layer.
[0064]
(Example 8)
FIG. 23 is an operation block diagram of the pinching prevention device according to the eighth embodiment of the present invention. FIG. 23 also shows a cross section of the piezoelectric sensor 8. In this embodiment, the piezoelectric sensor 8 of another embodiment is formed in a laminated film shape and replaced with the following configuration. Two piezoelectric materials 13a and 13b provided with electrodes 14c and 14d, 14e and 14f are laminated, and a voltage signal having a specific frequency is applied to the electrodes 14e and 14f of one piezoelectric material 13b constituting the piezoelectric sensor 8. The contact detection means 17 calculates a pressure applied to the piezoelectric sensor 8 based on an output signal generated between the electrodes 14c and 14d of the other piezoelectric material 13a due to the vibration. The pressure calculation unit 40 and a contact determination unit 41 that determines contact of an object based on an output signal of the pressure calculation unit 40 are provided. The contact detection means 17 includes a first band pass filter 42 having a frequency f3 generated by the signal applying unit 39 as a center frequency, and a second band pass filter 43 having a center frequency f1 in FIG. Since the piezoelectric sensor 8 of the present embodiment is in the form of a film, the thickness is thin even when laminated, so that the radius of curvature of the deformed portion can be kept small. Therefore, the displacement can be increased and the output can be increased.
[0065]
The outside of the piezoelectric sensor 8 may be sealed with a protective layer such as PET or a metal film for electrical shielding.
[0066]
Next, the operation and action will be described.
[0067]
In short, in the other embodiments, the pinching is detected by the output of the piezoelectric sensor, whereas in this embodiment, the pinching is detected by the change in the output of the piezoelectric sensor.
[0068]
In the piezoelectric sensor 8, the piezoelectric material 13 b vibrates according to the voltage signal having the frequency f <b> 3 generated by the signal applying unit 39. In response to the vibration, a piezoelectric electromotive force is generated in the piezoelectric material 13a. The generated output signal is filtered by the first bandpass filter 42. Signal waveforms of the oscillation signal V3 of the signal applying unit 39 and the output V4 of the first bandpass filter 42 at this time are as shown in FIGS. 24 (a) and 24 (b), respectively. 24A and 24B, it is assumed that the vertical axis is V3 and V4, the horizontal axis is time t, and the object Pr contacts the piezoelectric sensor 8 and the pressure Pr1 is applied at time t1. 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 as shown in FIG. 25 between the amplitude D4 of V4 and the pressure Pr, and D4 has a characteristic of decreasing as the pressure Pr increases. Since this characteristic varies depending on the oscillation frequency f3, the shape of the piezoelectric materials 13a and 13b, etc., it may be optimized in advance by experiments or the like according to the application. The pressure calculation unit 40 calculates Pr1 from D41 based on the relationship of FIG. The contact determination unit 41 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. When 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 caught. In this embodiment, since the piezoelectric sensor is thinly formed into a film and the radius of curvature of the deformed portion is reduced, the amplitude D4 is increased as a whole, and it becomes easy to see the change of Pr1, so that the accuracy of the determination is increased. Can do.
[0069]
For example, when the vibration at the time of traveling of the vehicle is applied to the piezoelectric sensor 8 by the above action, the piezoelectric sensor 8 is a type that detects vibration and distortion as in the first embodiment. Although it may be difficult to distinguish between the output signal and the output signal of the piezoelectric sensor 8 due to the contact of the object, the piezoelectric sensor 8 of the present embodiment outputs a signal corresponding to the contact pressure of the object, and the contact detection means 17 Since the contact pressure of the object is detected by the pressure calculation unit 40 and the contact is determined by the contact determination unit 41, the contact of the object can be accurately detected even when the above-described traveling vibration is applied.
[0070]
The contact determination unit 41 determines that the 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 the rate of change or variation pattern of Pr1.
[0071]
Further, as shown in FIG. 23, the contact detection unit 17 includes a second bandpass filter 43 having f1 as the center frequency, and the contact determination unit 41 includes both the second bandpass filter 43 and the pressure calculation unit 40. It is good also as a structure which detects the contact of an object based on this output signal. The operation of this configuration will be described below. FIG. 24 (c) shows the signal waveform of the output V5 of the second bandpass filter 43. FIG. In the figure, the vertical axis represents V5 and the horizontal axis represents time t. When an object comes into contact with the piezoelectric sensor at time t1, vibration at a frequency f3 due to the piezoelectric material 13a and vibration in the vicinity of f1 lower than f3 due to distortion due to contact with the object are applied to the piezoelectric material 13a, and f3 is applied from the piezoelectric material 13a. And a signal having a frequency component superimposed on f1 are output. Based on this output signal, the pressure calculation unit 40 calculates the pressure Pr via the first bandpass filter 42 as described above, and the output V5 of the second bandpass filter 43 is, for example, as shown in FIG. A signal having an amplitude D5 appears at a certain frequency f1. In the contact determination unit 41, for example, when D5 is equal to or greater than a certain threshold value D50, it is assumed that an external vibration such as a driving vibration of the vehicle is applied to the piezoelectric sensor 8, and the object is contacted 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 rate of change of D5, the variation pattern, and the value of Pr.
Accordingly, the presence or absence of external vibration is determined from the output signal of the piezoelectric sensor 8, and the contact determination is performed by switching the threshold value for contact determination according to the presence or absence of the external vibration. Therefore, the object is detected only by vibration detected by the piezoelectric sensor or only by pressure. The detection accuracy is improved as compared with the case of detecting the contact.
[0072]
The configurations of the above-described embodiments are not limited to each other, and can be partially replaced or combined with the configurations shown in other embodiments. Just choose.
[0073]
In addition, regarding the arrangement | positioning of the piezoelectric sensor in the pinching prevention apparatus of a motor vehicle, you may arrange | position to the vehicle body, weather strip, side visor, etc. by the side of a window frame, and may arrange | position to a window glass side. In the case of the hard top type, it may be arranged on the vehicle body side instead of the window frame.
[0074]
In the above-described embodiment, the pinch prevention device using the piezoelectric sensor for the power window for the vehicle has been described. Good. Basically, the present invention can be applied to a case in which the gap with the abutting member changes due to the movement of the moving member, that is, there is a possibility that some object may be sandwiched.
[0075]
In the case of a train door or an automatic door of a front door, it is considered that two moving members are facing each other. However, the moving member is included in the present invention by placing the other viewed from one moving member as an abutting member. It is.
[0076]
【The invention's effect】
As described above, in the pinching prevention device according to claim 1 of the present invention, the piezoelectric sensor includes the electrodes formed on both surfaces of the piezoelectric material, the insulator covering the electrodes, and the shield member covering the insulators. In addition, a piezoelectric material and an electrode are disposed through a buffer material so that a piezoelectric material and an electrode are disposed at least in a portion that receives a load due to contact with an object. The thickness of the piezoelectric material in the portion that receives a load due to contact with the object is made thinner than the thickness of the piezoelectric material in the portion that does not receive a load due to contact with the object. Thereby, the displacement with respect to the same load becomes large (that is, it becomes easy to deform), the strain increases, the generated charge increases, the polarization current increases, and the output becomes large.
[0077]
Further, since at least the contact part is made thin, it is easy to be deformed, and there is an effect that the radius of curvature of the deformed part is easily reduced and the output is increased.
[0078]
Further, the claims of the present invention 2 Since the squeezing prevention device is accordion-shaped, it can be easily deformed, and the radius of curvature of the deformed portion can be easily reduced to increase the output.
[Brief description of the drawings]
FIG. 1 is an external view of a piezoelectric sensor and a pinching prevention device according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of the apparatus.
3A is a sectional view of a conventional piezoelectric sensor. FIG.
(B) Sectional view of the piezoelectric sensor in Example 1 of the present invention
FIG. 4 is a sectional view of the piezoelectric sensor
FIG. 5 is an external configuration diagram of the piezoelectric sensor.
FIG. 6 is a characteristic diagram of the piezoelectric sensor.
FIG. 7 is a block diagram of the pinching prevention device.
FIG. 8 is a circuit diagram for detecting disconnection of the apparatus.
FIG. 9 is a characteristic diagram showing the filtering characteristics of the first filtering unit and the second filtering unit of the apparatus.
FIG. 10 is a characteristic diagram showing a criterion for determining contact of an object with the opening / closing part of the apparatus
FIG. 11 is a flowchart showing the operation of the apparatus.
FIG. 12 is a characteristic diagram comparing changes with time in the generated voltage of the piezoelectric material of the apparatus and a conventional piezoelectric material.
FIG. 13 is a cross-sectional view showing an arrangement configuration of piezoelectric sensors in Embodiment 2 of the present invention.
FIG. 14A is a sectional view of a conventional piezoelectric sensor.
(B) Sectional view of the piezoelectric sensor in Example 2 of the present invention
FIG. 15A is a configuration diagram of the piezoelectric sensor.
(B) Configuration diagram of a piezoelectric sensor in another embodiment of the present invention
FIG. 16 is a cross-sectional view showing an arrangement configuration of a piezoelectric sensor according to a third embodiment of the present invention.
FIG. 17 is a cross-sectional view showing an arrangement configuration of a piezoelectric sensor in Example 4 of the present invention.
FIG. 18A is a configuration diagram of the piezoelectric sensor.
(B) Configuration diagram of a piezoelectric sensor in another embodiment of the present invention
FIG. 19A is a cross-sectional view of a piezoelectric sensor according to a fifth embodiment of the present invention before contact with an object.
(B) Sectional view after the object of the piezoelectric sensor comes into contact
FIG. 20 is a cross-sectional view showing an arrangement configuration of a piezoelectric sensor in Example 6 of the present invention.
FIG. 21 is a cross-sectional view showing an arrangement configuration of a piezoelectric sensor according to a seventh embodiment of the present invention.
FIG. 22 is a sectional view of the same piezoelectric sensor.
FIG. 23 is an operation block diagram of the pinching prevention device according to the eighth embodiment of the present invention.
24A is a waveform characteristic diagram of an oscillation signal V3 of a signal applying unit of the apparatus. FIG.
(B) Waveform characteristic diagram of output V4 of the first bandpass filter
(C) Waveform characteristic diagram showing the output waveform of the output V5 of the second bandpass filter
FIG. 25 is a characteristic diagram showing the relationship between the amplitude D4 of the output V4 of the first bandpass filter of the same device and the pressure Pr.
[Explanation of symbols]
1 Window glass (moving member)
5 Control means
6 Window frame (contact member)
7 Opening and closing part
8 Piezoelectric sensor
9 objects
11 Contact area
34 Thin parts
R11, R12, R21, R22, R31, R32, R41, R42, R51, R52 Curvature radius of deformation part

Claims (2)

A piezoelectric sensor disposed in an opening / closing part composed of a moving member and a contact member;
Control means for controlling the opening and closing operation of the opening and closing unit by detecting the object sandwiched in the opening and closing unit based on the output of the piezoelectric sensor, the piezoelectric sensor, electrodes formed on both surfaces of the piezoelectric material,
An insulator covering the electrode and a shield member covering the insulator, and disposed via a buffer material so that the piezoelectric material and the electrode are disposed at least in a portion that receives a load due to contact with the object. The thickness of the piezoelectric sensor in the portion having the piezoelectric material is made thinner than the thickness of the piezoelectric sensor in the portion not having the piezoelectric material, and the thickness of the piezoelectric material in the portion receiving the load due to the contact with the object is reduced by the contact with the object. An anti-pinch device characterized in that it is thinner than the thickness of the piezoelectric material in the portion not receiving the load. A piezoelectric sensor disposed in an opening / closing part composed of a moving member and a contact member;
Control means for controlling the opening / closing operation of the opening / closing part by detecting the object sandwiched in the opening / closing part based on the output of the piezoelectric sensor, and the piezoelectric sensor has an accordion shape in order to increase the output. An anti-pinch device that reduces the radius of curvature of a deformed part caused by contact with an object.

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