JP2004189431A - Contact detection device and switchgear - Google Patents

Abstract

Conventionally, a safety shoe and a limit switch have been used to detect contact with an elevator door, but there has been a problem that sensitivity is poor.
A flexible piezoelectric sensor disposed along an end of an elevator door, and determination means for determining contact of an object to the elevator door based on an output signal of the piezoelectric sensor. Is provided, it is possible to detect with high sensitivity when a human body or the like comes into contact with the door 4 of the elevator.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a contact detection device that detects contact of a human body, an object, or the like with a door of an elevator such as an elevator, and an opening / closing device.
[0002]
[Prior art]
As shown in FIG. 9, a conventional device for detecting contact or entrapment of an elevator door, when a human body or the like comes into contact with or is entrapped in an elevator door 1, a safety shoe 2 is pushed in and a mechanism such as a cam is used. After that, the door is opened by detecting with the switch 3 (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-44148 A
[Problems to be solved by the invention]
However, the conventional method has a problem that it takes time until the switch is activated by being sandwiched between the safety shoes and the sensitivity is poor.
[0005]
An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a contact detection device and an opening / closing device capable of detecting, with high sensitivity, when a human body or the like touches an elevator door.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides a flexible piezoelectric sensor disposed along an end of an elevator door, and contacts an object to the elevator door based on an output signal of the piezoelectric sensor. By providing the determination means, it is possible to provide a contact detection device and an opening / closing device that can detect with high sensitivity when a human body or the like comes into contact with an elevator door.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
In order to solve the above-mentioned problem, the invention of claim 1 provides a flexible piezoelectric sensor in which a flexible piezoelectric sensor is disposed along an end of an elevator door, and an output signal of the piezoelectric sensor. A determination means for determining contact of an object with the elevator door based on the above means enables highly sensitive detection when a human body or the like touches the elevator door. Further, the invention according to claim 2 has an elastic body provided with a piezoelectric sensor and a support portion for supporting the elastic body and fixing the elastic body to an elevator door, so that when a human body or the like comes into contact with the elevator door. Sensing can be performed with high sensitivity, and the attachment and detachment of the contact detection device from the door becomes easy, and maintenance becomes easy. According to the third aspect of the present invention, since the elastic body and the supporting portion are integrally formed, the number of manufacturing steps is reduced, and the manufacturing is facilitated. Further, according to the present invention, a support portion is provided at a front end portion of a door, an opening is provided at a front end portion of the support portion, and the piezoelectric sensor has a convex portion protruding from the opening portion. Even when a strong external force is applied, disconnection or the like can be suppressed. According to the fifth aspect of the present invention, the sensitivity is further improved by a configuration in which a gap is provided inside the elastic body. According to the sixth aspect of the present invention, since the judging means is mounted on the supporting portion, it is not necessary to separately provide and judge the judging means, and the judging means can be integrally attached and detached. According to a seventh aspect of the present invention, the piezoelectric sensor has a plurality of electrodes for signal derivation and a disconnection detecting resistor connected between the electrodes, and the piezoelectric sensor includes a disconnection detecting resistor. Since the disconnection of the electrode can be detected, the reliability of the device is improved. Further, according to the invention of claim 8, the piezoelectric sensor has a plurality of electrodes for signal derivation, and both ends of the piezoelectric sensor are connected to a judging means, and the judging means detects the presence or absence of conduction of the electrodes, thereby detecting the piezoelectricity. Since the disconnection of the sensor is determined, the reliability of the device is improved. According to a ninth aspect of the present invention, there is provided the contact detecting device according to any one of the first to eighth aspects, and a driving unit for driving a door, wherein the contact is released when the contact is determined based on an output signal of the determining unit. It has a control means for controlling the driving means. When the contact is determined, the contact is released, so that unnecessary pinching can be prevented.
[0008]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0009]
(Example 1)
The first embodiment will be described with reference to FIG. FIG. 1 is an external view of a contact detection device and an opening / closing device according to the first embodiment of the invention, and shows a case where the invention is applied to an elevator door 4. FIG. 2 is a cross-sectional configuration diagram of a main part at an end 5 of the door 4 of FIG. First, the configuration of the contact detection device according to the first embodiment of the present invention is as follows. 1 and 2, the door 4 is provided in the elevator cage 6, and the opening 7 is closed. Reference numeral 8 denotes a support for holding the elastic body 9, reference numeral 10 denotes a piezoelectric sensor, reference numeral 11 denotes fixing means for fixing the support 8 to the door 4, and reference numeral 12 denotes a gap provided in the support 8. A P plate or the like, which is the determination means 13, is installed in the gap 12. The piezoelectric sensor 10 is installed inside the elastic body 9, and the elastic body 9 is provided with a void 14.
[0010]
FIG. 3 is a configuration diagram of the piezoelectric sensor 10. As shown in FIG. 3, the piezoelectric sensor 10 has a coaxial cable shape formed by concentrically laminating a composite piezoelectric layer 15 as a piezoelectric material and a center electrode 16 and an outer electrode 17 as electrodes sandwiching the composite piezoelectric layer 15. The elastic member 9 is provided on the outermost layer, and the overall structure is excellent in flexibility. The elastic body 9 is provided with a void portion 14 and is formed integrally with the support portion 8.
[0011]
The piezoelectric sensor 10 is manufactured by the following steps. First, a chlorinated polyethylene sheet and (40 to 70) vol% piezoelectric ceramic (here, lead zirconate titanate) powder are uniformly mixed in a sheet shape by a roll method. After the sheet is finely cut into pellets, these pellets are continuously extruded together with the center electrode 16 to form the composite piezoelectric layer 15. Then, the outer electrode 17 is wound around the composite piezoelectric layer 15. The elastic body 9 and the support portion 8 are continuously extruded around the outer electrode 17. Finally, a DC high voltage of (5 to 10) kV / mm is applied between the center electrode 16 and the outer electrode 17 to polarize the composite piezoelectric layer 15.
[0012]
By forming the support 8 and the elastic body 9 by integral molding as described above, the bonding operation or the like becomes unnecessary, and the working efficiency is improved.
[0013]
In addition, other than the integral molding, a method of fixing the elastic body to the supporting portion by bonding or screwing is also possible.
[0014]
By providing the gap 14, when the pressing by the object or the like is applied to the piezoelectric sensor 10 at the time of contact, the degree of deformation of the piezoelectric sensor 10 is increased due to the collapse of the gap 14, and the output signal from the piezoelectric sensor 10 is reduced. Since it increases, the detection load at the time of contact detection can be reduced, stress and damage to the contacted object can be reduced, and detection can be performed with high sensitivity. It should be noted that even in the case where the inside of the elastic body is filled without providing the void portion 14, the sensitivity of the contact detection is higher than in the related art.
[0015]
For the chlorinated polyethylene sheet, a mixture of amorphous chlorinated polyethylene and crystalline chlorinated polyethylene is used. In this case, 75 wt% of amorphous chlorinated polyethylene having a molecular weight of 60,000 to 150,000 and a molecular weight of 200,000 at a crystallinity (15 to 25)% are taken into consideration in consideration of the workability, flexibility, piezoelectric characteristics, and the like of extrusion. It has been experimentally found that a chlorinated polyethylene in which ｗｔ400,000 crystalline chlorinated polyethylene is mixed at 25 wt% is preferable. The mixed chlorinated polyethylene can include up to about 70 vol% piezoceramic powder.
[0016]
When the piezoelectric ceramic powder is added to the mixed chlorinated polyethylene, it is preferable that the piezoelectric ceramic powder is immersed and dried in a solution of a titanium coupling agent in advance. By this treatment, the surface of the piezoelectric ceramic powder is covered with the hydrophilic groups and the hydrophobic groups contained in the titanium coupling agent. The hydrophilic group prevents aggregation of the piezoelectric ceramic powders, and the hydrophobic group increases the wettability between the mixed chlorinated polyethylene and the piezoelectric ceramic powder. As a result, the piezoelectric ceramic powder can be uniformly added to the mixed chlorinated polyethylene in a large amount up to 70 vol%. Instead of immersion in the above-mentioned titanium coupling agent solution, it was found that the same effect as above was obtained by adding the titanium coupling agent at the time of rolling the mixed chlorinated polyethylene and the piezoelectric ceramic powder. . This treatment is excellent in that no special immersion treatment in a titanium coupling agent solution is required.
[0017]
As the center electrode 16, a normal metal single wire or a metal stranded wire may be used, but here, an electrode in which a metal coil 19 is wound around an insulating polymer fiber 18 is used. As the insulating polymer fiber 18 and the metal coil 19, a polyester fiber and a copper alloy containing 5 wt% of silver, which are commercially used in an electric blanket, are preferable.
[0018]
The outer electrode 17 has a configuration in which a band-shaped electrode in which a metal film is adhered on a polymer layer is wound around the composite piezoelectric layer 15. An electrode having polyethylene terephthalate (PET) as the polymer layer and an aluminum film adhered thereon has high thermal stability at 120 ° C. and is mass-produced commercially. 17 is preferable. Since it is difficult to solder the aluminum film when connecting this electrode to the sandwiching determination means 13, it is connected by, for example, caulking or eyelets. Alternatively, a configuration may be employed in which a metal single-wire coil or a metal braid is wound around the aluminum film of the outer electrode 17 to establish conduction with the aluminum film, and the metal single-wire coil or the metal braid is sandwiched and soldered to the determination means 13. Since attachment is possible, work efficiency can be improved. In order to shield the piezoelectric sensor 10 from electric noise in the external environment, the outer electrode 17 is preferably wound around the composite piezoelectric layer 15 so as to partially overlap. When a copper film is used instead of an aluminum film, soldering is facilitated and work efficiency can be improved.
[0019]
As the elastic body 9, an elastic material such as rubber, which is more flexible and flexible than the composite piezoelectric layer 15, is used so that the piezoelectric sensor 10 is easily deformed when pressed by contact or pinching of an object. It is preferable to select a material in consideration of its properties and cold resistance, and specifically, to select a material at -30 ° C. to 85 ° C. with little decrease in flexibility. As such a rubber, for example, ethylene propylene rubber (EPDM), chloroprene rubber (CR), butyl rubber (IIR), silicon rubber (Si), thermoplastic elastomer, or the like may be used. With the configuration as described above, the minimum curvature of the piezoelectric sensor 10 is possible up to a radius of 5 mm.
[0020]
Further, the support section 7 is provided with fixing means 11 for fixing to the door 4. Here, a method is used in which a screw hole is provided in the support portion 8 and fixed to the door 4 with a screw. In addition to the screws, it is possible to use a fitting type or an adhesive, but it is difficult to attach and detach the screws.
[0021]
FIG. 4 is a configuration diagram of a main part of the piezoelectric sensor 10. 1 and 4, the piezoelectric sensor 10 is disposed along the end 5 of the door 4. A first resistor (not shown) as a resistor for detecting disconnection is connected between the center electrode 16 and the outer electrode 17 at one end 20 of the piezoelectric sensor 10 and molded with resin or the like. I have. The other end is provided with a judgment unit 13 integrated with the piezoelectric sensor 10. 21 is a cable for supplying power and outputting a detection signal, and 22 is a connector. The end portion 20 and the judging means 13 are folded at the upper end or the lower end of the door 4 and are disposed in the gap 12 of the support portion 8. Since the piezoelectric sensor 10 and the judging means 13 are integrated as described above, a cable or the like for connecting the piezoelectric sensor 10 and the judging means 13 is not required, so that the rationalization can be achieved. In order to remove extraneous electrical noise, it is preferable that the determination means 13 be entirely covered with a shield member and be electrically shielded. A strong electric field measure may be taken by adding a feedthrough capacitor, an EMI filter, or the like to the input / output unit of the determination unit 13.
[0022]
FIG. 5 is a block diagram of the contact detection device and the opening / closing device of the first embodiment. 5, 23 is a first resistor, 24 is a second resistor for detecting disconnection, 25 is a third resistor for deriving a signal from the piezoelectric sensor 10, and 26 is an output signal from the piezoelectric sensor 10. , A filtering unit that allows only a predetermined frequency component to pass therethrough, 27 a determination unit that determines entrapment based on an output signal from the filtering unit 26, and 28 a piezoelectric sensor 10 based on the voltage value formed by the first to third resistors. An abnormality determining unit for determining a disconnection abnormality, a driving unit for driving the door, a control unit for controlling the driving unit based on an output signal of the determining unit, and a determination result of the determining unit in the elevator. And 34, a power supply unit. The filtering unit 26 has a filtering characteristic of removing an unnecessary signal due to an elevator vibration or the like from an output signal of the piezoelectric sensor 10 and extracting a signal having a frequency component specific to contact with an object. In order to determine the filtering characteristics, the filtering characteristics may be optimized in consideration of the vibration characteristics of the elevator. Specifically, it is desirable to use a low-pass filter for extracting a signal component of about 10 Hz or less in order to remove vibration due to elevator driving or the like.
[0023]
Next, the operation will be described. As shown in FIGS. 1 to 4, in the first embodiment, a flexible piezoelectric sensor 10 is used to detect that a human body or the like has come into contact between the door 4 and the opening 7 of the elevator. Bendable along the end face portion of the horn. Therefore, the piezoelectric sensor 10 can be disposed at the upper end and the lower end of the door 4, bent and folded, and the resistance section 20 and the determination means 13 can be disposed in the gap 12. Thereby, the resistance portion 20 and the determination means 13 can be disposed in the support body 8 and the elastic body 9. Therefore, the screw which is the fixing means 11 of the support body 8 can be removed from the door 4 integrally by removing the screw. it can. Therefore, since the replacement can be performed simply by removing the screw and the connector 22, an effect that maintenance is easy can be obtained. Note that the determination means can be provided at a place other than the gap 12.
[0024]
Further, even if the end face of the door is bent, it is possible to dispose it along the end face. Therefore, since the door can be disposed even if the end face is not vertical, the rigidity is enhanced and the degree of freedom in design is improved.
[0025]
Next, a procedure for determining contact will be described below. A human body or an object enters between the door 4 and the opening 7, comes into contact with the piezoelectric sensor 10 provided at the end 5 of the door 4, and the piezoelectric sensor 10 is deformed by pressing the human body or the object.
[0026]
FIG. 6 is a characteristic diagram showing the output signal V of the filtering unit 26, the determination output J of the contact determination unit 27, and the voltage Vm applied to the driving unit 29 at this time. In FIG. 6, the vertical axis represents V, J, and Vm in order from the top, and the horizontal axis represents time t. At time t1, a voltage of + Vd is applied to the motor 29 to drive the door 4 in the closing direction. When the contact occurs, the piezoelectric sensor 10 outputs a signal (a signal component larger than the reference potential V0 in FIG. 6) corresponding to the acceleration of the deformation of the piezoelectric sensor 10 due to the piezoelectric effect. If the amplitude V-V0 of V from V0 is equal to or greater than D0, the contact determination unit 27 determines that a contact has occurred, and outputs a Lo → Hi → Lo pulse signal as a determination output at time t0. When this pulse signal is present, the control means 30 stops applying the + Vd voltage to the driving means 29, causes the display unit 31 to indicate that the entrapment has occurred, applies the -Vd voltage for a certain period of time, and opens the door 4. Drive in the direction to release the contact. When the contact is determined, an alarm may be generated from the display unit 31. When the contact is released, a signal (a signal component smaller than the reference potential V0 in FIG. 6) corresponding to the acceleration at which the deformation is restored is output from the piezoelectric sensor 10.
[0027]
Whether V is larger or smaller than V0 at the time of contact depends on the bending direction and the polarization direction of the piezoelectric sensor 10, the assignment of electrodes (which is the reference potential), and the supporting direction of the piezoelectric sensor 10. Therefore, the contact determination unit 27 may determine the contact based on the amplitude | V−V0 | of V from V0, and the contact can be determined regardless of the magnitude of V with respect to V0.
[0028]
Next, the procedure of disconnection determination in the abnormality determination unit 28 will be described below. In FIG. 5, the resistance values of the first to third resistors are R1, R2, R3, the voltage at point P is Vp, and the voltage of the power supply 32 is Vs. R1, R2, and R3 generally have a resistance of several mega to several tens of mega ohms. When the electrode of the piezoelectric sensor 10 is normal, Vp is a divided voltage value of R1 and the parallel resistance of R2 and R3 with respect to Vs. Here, since the resistance value of the composite piezoelectric layer 15 is usually several hundred megaohms or more, it hardly contributes to the parallel resistance value of R2 and R3, so that it is ignored in the calculation of the partial pressure value. When the electrode of the piezoelectric sensor 10 is disconnected, the point Pa or the point Pb is equivalently opened, so that Vp is a partial pressure value of R2 and R3. When the electrodes are short-circuited, equivalently, the points Pa and Pb are short-circuited, so that Vp becomes equal to Vs. As described above, since the abnormality determination unit 28 detects an abnormality such as a disconnection or a short circuit of the electrode of the piezoelectric sensor 10 based on the value of Vp, the reliability can be improved.
[0029]
Due to the above-described operation, the flexible piezoelectric sensor 10 is arranged to be bent along the end face of the door 4 of the elevator, so that the contact can be detected with high sensitivity.
[0030]
In addition, the minimum curvature of the piezoelectric sensor is 5 mm in radius, and the piezoelectric sensor can be disposed on the bent portion of the door 4 up to the minimum curvature radius of 5 mm, so that rigidity is enhanced and the degree of freedom in design is improved.
[0031]
Further, the piezoelectric sensor has a plurality of electrodes for signal derivation and a disconnection detecting resistor connected between the electrodes, and the disconnection of the electrode of the piezoelectric sensor can be detected by the disconnection detecting resistor. Therefore, the reliability of the device is improved.
[0032]
The apparatus further includes a contact detection device using a piezoelectric sensor and a driving unit that drives the door, and a control unit that controls the driving unit to release the contact when the contact is determined based on an output signal of the determination unit. Since the contact is sometimes released, it is possible to provide an opening / closing device that prevents an accident such as a bruise or a fall due to strong contact, or that prevents unnecessary pinching.
[0033]
As described above, a mixture of amorphous chlorinated polyethylene and crystalline chlorinated polyethylene is used as a raw material of the composite piezoelectric layer 15 of the piezoelectric sensor 10; Up to 80 vol% piezoceramic powder can be added and the pellets can be easily extruded. The extruded composite piezoelectric layer 15 also has excellent flexibility. However, since the composite piezoelectric layer 15 has low rigidity, it is not practical because it easily deforms at about 80 ° C. or higher. In order to impart sufficient rigidity to the composite piezoelectric layer 15 such that the composite piezoelectric layer 15 hardly deforms even at 120 ° C., vulcanization is required. On the other hand, when only crystalline chlorinated polyethylene is used, the composite piezoelectric layer 15 has sufficient rigidity so that it is hardly deformed even at 120 ° C., so that vulcanization is not required, but extrusion is difficult. Also, the piezoelectric ceramic powder can be added only up to about 40 vol%.
[0034]
The piezoelectric sensor 10 of the present invention has a composite piezoelectric layer 15 made of a mixed composition containing amorphous chlorinated polyethylene, crystalline chlorinated polyethylene, and piezoelectric ceramic powder, and the composite piezoelectric layer 15 is made of amorphous. It has both advantages such as the flexibility of high-grade chlorinated polyethylene and the high-temperature durability of crystalline chlorinated polyethylene, and can operate at 120 ° C. for 1000 hours or more. Further, the vulcanizing step required for producing general synthetic rubber is not required for the piezoelectric sensor 10 of the present invention.
[0035]
With the above configuration, the contact detection device can be installed in a range thinner than the thickness of the elevator door 4, so that a conventional safety shoe and mechanism are not required, and the inside of the elevator cage body is reduced by the thickness. A large volume can be taken.
[0036]
(Example 2)
A second embodiment will be described with reference to FIG. FIG. 7 is a sectional view of a main part of a contact detection device and an opening / closing device according to the second embodiment of the invention. The second embodiment is different from the first embodiment in that an elastic body 36 provided with a support portion 33 at the front end of the door 4, an opening 34 at the front end of the support portion 33, and a piezoelectric sensor 35 is provided. It has a convex portion 37 protruding from the opening 34. The elastic body 36 is installed on a holding section 38 provided on the support section 33.
[0037]
With the above configuration, when the door 4 of the elevator operates and a human body or an object comes into contact with the tip of the elevator, the projection 37 is pressed, and the piezoelectric sensor 35 detects the acceleration. The following operation is the same as in the first embodiment. With the above configuration, even if a strong force is applied to the tip of the door 4, the contact can be detected without breaking the piezoelectric sensor 35.
[0038]
(Example 3)
A third embodiment will be described with reference to FIGS. FIG. 8 is a sectional view of a main part of a contact detection device and an opening / closing device according to the third embodiment of the invention. The third embodiment is different from the second embodiment in that an elastic body 42 provided with a support portion 39 at the front end of the door 4, an opening 40 at the front end of the support portion 39, and a piezoelectric sensor 41 is provided. It has a projection 43 protruding from the opening 40. The elastic body 42 is provided on a holding section 44 provided on the support section 39, and has a gap 45.
[0039]
With the above configuration, when the door 4 of the elevator is operated and a human body or an object comes into contact with the tip of the elevator, the projection 37 is pressed and the piezoelectric sensor 41 detects the acceleration. The following operation is the same as in the first embodiment. With the above configuration, even if a strong force is applied to the tip of the door 4, the piezoelectric sensor 41 can detect contact without breaking, and by providing the gap 45, pressing by an object or the like at the time of contact can be applied to the piezoelectric sensor 41. When the voltage is applied, the degree of deformation of the piezoelectric sensor 41 increases due to the collapse of the gap 45, and the output signal from the piezoelectric sensor 41 increases, so that the detection load at the time of contact detection can be reduced, and Stress and damage can be reduced, and detection can be performed with high sensitivity.
[0040]
Further, in the first to third embodiments, the present invention is applied to the case where the present invention is applied to a single-sided door as an elevator door. Even if there is a bent portion, contact or pinching can be detected without erroneous detection.
[0041]
In the first to third embodiments, the flexible piezoelectric sensor is provided on the door. However, instead of the piezoelectric sensor, a type of pressure sensing means for detecting the capacitance between the electrodes and Other pressure-sensitive means, such as a pressure-sensitive means of which conductivity changes depending on the pressure, may be used.
[0042]
【The invention's effect】
According to the above invention, since the flexible piezoelectric sensor is disposed to bend along the end surface of the door of the elevator, even if there is a bent portion at the time of disposing the door and the door, contact can be detected without erroneous detection. There is such an effect.
[Brief description of the drawings]
FIG. 1 is an external view of a contact detection device and an opening / closing device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional configuration view of a main part of the first embodiment of the present invention. FIG. FIG. 4 is a configuration diagram of a main part of a piezoelectric sensor of the device. FIG. 5 is a block diagram of the device. FIG. 6 is an output signal V from a filtering unit of the device, a determination output J of a contact determination unit, and a signal to a driving unit. FIG. 7 is a characteristic diagram showing an applied voltage Vm. FIG. 7 is a cross-sectional view of a main part of a contact detection device and a switching device according to a second embodiment of the invention. FIG. Fig. 9: Configuration diagram of a conventional elevator door [Explanation of reference numerals]
4 Door 5 Ends 8, 33, 39 Supports 9, 36, 42 Elastic bodies 10, 35, 41 Piezoelectric sensor 13 Judging means 16 Center electrode (electrode)
17 Outer electrode (electrode)
23 1st resistor (resistor)
29 Driving means 30 Control means 34, 40 Opening 37, 43 Convex 45 Spacing

Claims (9)

A contact detection device comprising: a flexible piezoelectric sensor disposed along an end of an elevator door; and determination means for determining contact of an object with the elevator door based on an output signal of the piezoelectric sensor. . The contact detection device according to claim 1, further comprising: an elastic body provided with a piezoelectric sensor; and a supporting portion that supports the elastic body and fixes the elastic body to an elevator door. 3. The contact detection device according to claim 2, wherein the elastic body and the support are integrally formed. The contact detection device according to claim 1, wherein a support portion is provided at a front end portion of the door, an opening is provided at the front end portion of the support portion, and the piezoelectric sensor has a convex portion protruding from the opening portion. 5. The contact detection device according to claim 4, wherein a void is provided inside the elastic body. The contact detection device according to claim 1, wherein the determination unit is mounted on a support. The contact detection device according to any one of claims 1 to 6, wherein the piezoelectric sensor has a plurality of electrodes for signal derivation, and a disconnection detection resistor connected between the electrodes. The piezoelectric sensor has a plurality of electrodes for signal derivation, and both ends of the piezoelectric sensor are connected to a determination unit, and the determination unit determines whether the piezoelectric sensor is disconnected by detecting whether or not the electrodes are conductive. The contact detection device according to any one of claims 6 to 6. 9. A control device comprising: the contact detection device according to claim 1; and a driving unit that drives a door, wherein the control unit controls the driving unit to release the contact when the contact is determined based on an output signal of the determination unit. Switchgear.

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