JP3680779B2 - Pressure-sensitive sensor and contact detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric pressure sensor and a contact detection device for detecting contact of an object.
[0002]
[Prior art]
Conventionally, this type of piezoelectric pressure sensor, as a detection principle, outputs a voltage signal according to the acceleration of the displacement due to the piezoelectric effect when the pressure sensor itself is displaced due to external vibration, bending, load, etc. It was something to do.
[0003]
[Problems to be solved by the invention]
However, the conventional pressure-sensitive sensor has a problem that, for example, when an object contacts at a very low speed, contact detection cannot be performed because the deformation acceleration is small.
[0004]
The present invention solves the above-described conventional problems, and an object thereof is to provide a piezoelectric pressure sensor and a contact detection device that can detect contact of an object regardless of contact speed.
[0005]
[Means for Solving the Problems]
In order to solve the above-described conventional problems, a pressure-sensitive sensor according to the present invention includes a flexible piezoelectric sensor having a flexible piezoelectric layer and a flexible electrode, and a non-linear displacement with respect to a load. A non-linear flexible member that deforms when a pressing load exceeds a predetermined value, and the piezoelectric sensor is in contact with at least a part of the non-linear flexible member, and is deformed by displacement of the non-linear flexible member. When the pressure load on the pressure sensor exceeds a predetermined value, the non-linear bending member is suddenly deformed, and the piezoelectric sensor is also suddenly deformed by the displacement of the non-linear bending member. A sufficiently large output signal can be obtained from the piezoelectric sensor, and if this signal is used, the contact of the object can be detected regardless of the contact speed.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, there is provided a flexible piezoelectric sensor having a flexible piezoelectric layer and a flexible electrode, and deformed when the displacement with respect to the load is non-linear and the pressing load exceeds a predetermined value. And the piezoelectric sensor is in contact with at least a part of the nonlinear flexible member and is deformed by the displacement of the nonlinear flexible member, and a pressure load applied to the pressure-sensitive sensor by an object is predetermined. When the value exceeds the value, the nonlinear flexible member is suddenly deformed, and the piezoelectric sensor is also suddenly deformed by the displacement of the nonlinear flexible member, so that an output signal having a magnitude sufficient to detect contact of the object is generated. It can be obtained from a sensor, and if this signal is used, the contact of an object can be detected regardless of the contact speed.
[0007]
According to a second aspect of the present invention, the non-linear deflection member and the piezoelectric sensor are arranged in a deformation means that can be deformed by a load. Therefore, the deformation means can support the piezoelectric sensor and the flexible member, and can be easily deformed and is practical.
[0008]
The invention described in claim 3 is a flexible piezoelectric sensor having a flexible piezoelectric layer and a flexible electrode, and is deformed when the amount of displacement relative to the load is non-linear and the pressing load exceeds a predetermined value. The non-linear flexible member, the non-linear flexible member and the piezoelectric sensor are arranged in a deforming means which can be deformed by a load, and the piezoelectric sensor is arranged at least through the deforming means between the non-linear flexible member and the piezoelectric sensor. The piezoelectric sensor is configured to be deformed prior to the nonlinear flexible member when a load is applied, and then the nonlinear flexible member is deformed. With this configuration, the piezoelectric sensor is deformed before the nonlinear flexible member is deformed, and the contact of the object can be detected.
[0009]
According to a fourth aspect of the present invention, the deforming means has a hollow portion at least on the side that receives a load from the nonlinear deflecting member, and is formed so that at least one of the nonlinear deflecting member and the piezoelectric sensor is easily deformed. It is characterized by. With this configuration, when an object comes into contact, the piezoelectric sensor is more easily deformed, so that the output signal is larger and the contact determination is easier.
[0010]
According to a fifth aspect of the present invention, the nonlinear flexible member is formed of a thin elastic body that is formed in a band shape and has a convex portion. With this configuration, the non-linear flexible member has a characteristic that the amount of displacement with respect to the load is non-linear when the pressing load is increased to a predetermined value or more, and is deformed into a concave shape when the pressing load is stopped. Regardless of the contact speed of the piezoelectric sensor, a large output appears in the piezoelectric sensor due to abrupt deformation of the non-linear flexible member.
[0011]
According to a sixth aspect of the present invention, the convex portion side of the nonlinear flexible member is a load receiving side, and the piezoelectric sensor is disposed on the convex portion side of the nonlinear flexible member. With this configuration, the piezoelectric sensor itself can be deformed and detected before the nonlinear flexure member is deformed, and vibration can be detected particularly when the contacting object vibrates.
[0012]
According to a seventh aspect of the present invention, the pressure sensor according to any one of the first to sixth aspects and an output signal of a piezoelectric sensor disposed in the pressure sensitive sensor are used to detect the object to the pressure sensitive sensor. And a determination means for determining contact, so that contact of an object can be detected regardless of the contact speed.
[0013]
According to an eighth aspect of the present invention, the determination means determines whether or not an object is kept in contact with the pressure sensor based on an output signal of the piezoelectric sensor, and the static load detection type is a piezoelectric pressure sensor. The operation similar to the pressure-sensitive switch can be realized, improving usability.
[0014]
According to the ninth aspect of the present invention, the pressure-sensitive sensor is disposed in an opening / closing part of a vehicle or a building, and the determination means determines whether the object is caught in the opening / closing part based on an output signal of the piezoelectric sensor. It can be used to prevent inadvertent pinching in buildings.
[0015]
In a tenth aspect of the present invention, the pressure-sensitive sensor is disposed in a bumper of a moving body such as an automatic transport vehicle, and the determination unit determines whether or not the moving body and the object are in contact based on an output signal of the piezoelectric sensor. Therefore, it can be used to prevent inadvertent collision between the moving body and the object.
[0016]
In the eleventh aspect of the invention, the pressure-sensitive sensor is disposed in a living place such as a chair, a seat, a bedding, a bathtub, a toilet seat, and a floor, and the determination means is based on an output signal of the piezoelectric sensor and the human body in the living place. It is used to determine the presence or absence, and can be used as human body information for device control in the house and for watching life.
[0017]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
(Example 1)
FIG. 1 is an external view of a pressure sensor in Embodiment 1 of the present invention, and FIG. 2 is a block diagram of a contact detection apparatus using the pressure sensor. In FIG. 1, a pressure-sensitive sensor 1 includes a deforming means 2 made of an elastic member, a non-linear deflection member 3, and a flexible sheet-like piezoelectric sensor 4. As the non-linear flexible member 3, for example, a belt-like thin elastic body having a convex shape as used in convex measures is used. Such a belt-like thin elastic body has a characteristic that when a pressing load is set to a predetermined value or more, it is suddenly deformed into a concave shape and is restored to its original shape when the load application is stopped.
[0019]
In FIG. 2, the piezoelectric sensor 4 has a piezoelectric layer 4a made of a flexible piezoelectric material such as polyvinylidene fluoride or piezoelectric rubber, and flexible electrodes 4b and 4c formed on both surfaces of the piezoelectric layer 4a. . Reference numeral 5 denotes determination means for determining contact of an object with the pressure sensor 1 based on an output signal of the piezoelectric sensor 4.
[0020]
The operation and action of the above configuration will be described. FIG. 3 is an external view showing a state of deformation of the pressure sensor 1 when a load W is applied to the pressure sensor 1 by contact with an object, and FIG. 4 is a view of the load W and the displacement L of the pressure sensor 1 (FIG. 3). Reference) is a characteristic diagram showing the output signal D of the piezoelectric sensor 4 and the determination output J of the determination means. In FIG. 4, the vertical axis indicates W, L, D, J in order from the top, and the horizontal axis indicates time t.
[0021]
3 and 4, a load W is applied to the pressure sensor 1 by contact with an object, and when W becomes larger than W1 at time t1, the non-linear flexible member 3 is deformed into a concave shape, and L rapidly increases non-linearly. To do. The state at this time is the state shown in FIG. At this time, since the piezoelectric sensor 4 is also subjected to a large deformation, a large signal force appears in D. Then, the determination means 5 determines that there is an object contact if D is greater than D1, and sets J to Hi at time t2 and holds it.
[0022]
Next, when W is decreased and W becomes smaller than W1 at time t3, the nonlinear flexure member 3 is deformed into a convex shape and returns to its original shape, so that L rapidly decreases nonlinearly. At this time, since the piezoelectric sensor 4 is also subjected to a large deformation in the opposite direction, a large signal force having a polarity opposite to the above appears in D. Then, the determination means 5 determines that the contact of the object is lost if D is smaller than D2, and sets J to Lo at time t4.
[0023]
FIG. 5 is a flowchart showing the determination procedure. First, when starting, J is set to Lo as an initial value in step ST1 and no object contact. Next, if D is larger than D1 in step ST2, it is determined in step ST3 that there is an object contact, and J is set to Hi. If D is less than or equal to D1, the process waits for D to be greater than D1 in step ST2. Next, if D is smaller than D2 in step ST4, the process returns to step ST1 and it is determined that there is no object contact, and J is set to Lo. If D is greater than or equal to D2, the process waits for D to become smaller than D2 in step ST4.
[0024]
Due to the above action, when the pressure load on the pressure-sensitive sensor by the object becomes a predetermined value or more, the nonlinear flexure member is suddenly deformed, and the piezoelectric sensor is also suddenly deformed by the displacement of the nonlinear flexure member. An output signal having a magnitude sufficient to detect contact can be obtained from the piezoelectric sensor, and a piezoelectric sensor that can detect contact of an object regardless of the contact speed can be realized.
[0025]
Further, the non-linear bending member is formed of a thin elastic body formed into a band shape and having a convex portion, and an elastic body used in a commercially available convex measure may be used, which is simple and highly practical.
[0026]
In addition, the non-linear flexible member and the piezoelectric sensor are arranged in a deforming means that can be deformed by a load, and the deforming means supports the non-linear flexible member and the piezoelectric sensor and easily deforms the non-linear flexible member and the piezoelectric sensor. Because it can, it is practical.
[0027]
Further, since the determination means determines the contact of the object with the pressure sensor based on the output signal of the piezoelectric sensor disposed in the pressure sensor, the piezoelectric type pressure sensor is used to detect the object regardless of the contact speed. A contact detection device capable of detecting contact can be realized.
[0028]
Further, the determining means determines whether or not the object is kept in contact with the pressure sensor based on the output signal of the piezoelectric sensor, and is the same as that of a static load detection type pressure sensitive switch. Operation is possible and usability is improved.
[0029]
(Example 2)
The invention of the second embodiment will be described with reference to FIG. FIG. 6A is a cross-sectional view of the pressure-sensitive sensor 1 when a flexible cable-shaped piezoelectric sensor 6 is used as the piezoelectric sensor. Since the cable-shaped piezoelectric sensor 6 is used, FIG. The degree of freedom of arrangement of the pressure sensor 1 is improved.
[0030]
FIG. 6B shows a configuration in which a distance is provided between the cable-shaped piezoelectric sensor 6 and the non-linear deflection member 3, and when a load is applied to the pressure-sensitive sensor 1, first, the cable-shaped piezoelectric sensor. 6 is deformed, and after that, the elastic member between the cable-shaped piezoelectric sensor 6 and the nonlinear flexible member 3 is sufficiently compressed, and then the nonlinear flexible member 3 is deformed. Therefore, if the object begins to contact and the cable-like piezoelectric sensor 6 is deformed, the contact of the object can be determined before the nonlinear flexure member 3 is deformed. Further, since there is a distance between the cable-shaped piezoelectric sensor 6 and the non-linear deflection member 3, for example, when the contacting object vibrates, the vibration characteristic can be detected by the cable-shaped piezoelectric sensor 6.
[0031]
FIG. 6C is a configuration in which the hollow portion 7 is further provided in the configuration of FIG. 6B, and the cable-like piezoelectric sensor 6 is more easily deformed when contacting an object, so that the output signal becomes larger. It becomes easy to make contact determination.
[0032]
(Example 3)
As a third embodiment, a pressure-sensitive sensor may be provided in an opening / closing part of a vehicle or a building, and the determination unit may determine whether an object is caught in the opening / closing part based on an output signal of the piezoelectric sensor. This configuration can be used to prevent inadvertent pinching in vehicles and buildings. In FIG. 7, the pressure-sensitive sensor 1 is disposed on the electric hatchback door 8 of the automobile to detect the object being caught between the electric hatchback door 8 and the body 9. From FIG. 7, the closing speed decreases as the rotation axis is approached, particularly at the place P. Therefore, it is desirable to dispose the pressure sensitive sensor 1 at such a place.
[0033]
(Example 4)
As a fourth embodiment, a pressure-sensitive sensor may be provided in a bumper of a moving body such as an automatic transport vehicle, and the determination unit may determine whether or not the moving body and an object are in contact based on an output signal of a piezoelectric sensor. . This configuration can be used to prevent inadvertent collision between the moving body and the object.
[0034]
(Example 5)
As Example 5, a pressure-sensitive sensor is disposed in a living place such as a chair, seat, bedding, bathtub, toilet seat, floor, etc., and the determination means determines the presence or absence of a human body in the living place based on the output signal of the piezoelectric sensor. It is good also as a structure. With this configuration, it can be used as human body information for device control in the house and for watching life.
[0035]
【The invention's effect】
As described above, since the pressure-sensitive sensor of the present invention is configured to include a non-linear flexible member, when the pressure load applied to the pressure-sensitive sensor by an object exceeds a predetermined value, the non-linear flexible member suddenly deforms, and the non-linear flexible member Since the piezoelectric sensor is also subjected to abrupt deformation due to the displacement of the sensor, an output signal large enough to detect the contact of the object can be obtained from the piezoelectric sensor, and the contact of the object can be detected regardless of the contact speed. effective.
[Brief description of the drawings]
FIG. 1 is an external view of a pressure sensor according to a first embodiment of the present invention. FIG. 2 is a block diagram of a contact detection device according to a first embodiment of the present invention. FIG. 4 is an external view showing a deformation state when a pressure is applied. FIG. 4 shows a load W when a load is applied to the pressure sensor, a displacement L of the pressure sensor, an output signal D of the piezoelectric sensor, and a determination result J of the determination means. FIG. 5 is a flow chart showing a determination procedure in the determination means of the contact detection device according to the first embodiment of the present invention. FIG. 6A is a sectional view of the pressure-sensitive sensor according to the second embodiment of the present invention. Sectional drawing of the pressure-sensitive sensor in Example 2 of this invention (The distance was put between the piezoelectric sensor and the nonlinear bending member).
(C) Sectional view of pressure-sensitive sensor in Example 2 of the present invention (provided with a hollow portion)
FIG. 7 is an external view in which a pressure-sensitive sensor according to a third embodiment of the present invention is disposed on a power hatch door of an automobile.
DESCRIPTION OF SYMBOLS 1 Pressure-sensitive sensor 2 Deformation means 3 Non-linear bending member 4 Piezoelectric sensor 5 Judgment means 6 Cable-shaped piezoelectric sensor (piezoelectric sensor)
7 Hollow part

Claims (11)

  A flexible piezoelectric sensor having a flexible piezoelectric layer and a flexible electrode, a non-linear flexible member that deforms when the displacement with respect to the load is non-linear and the pressing load exceeds a predetermined value, and the piezoelectric sensor Is a pressure-sensitive sensor which is in contact with at least a part of the nonlinear flexible member and is deformed by displacement of the nonlinear flexible member.   The pressure-sensitive sensor according to claim 1, wherein the non-linear flexible member and the piezoelectric sensor are arranged in a deformation means that can be deformed by a load. A flexible piezoelectric sensor having a flexible piezoelectric layer and a flexible electrode, a non-linear flexible member that deforms when the displacement with respect to the load is non-linear and the pressing load exceeds a predetermined value, and the non-linear flexible member And the piezoelectric sensor is disposed in a deformation means that can be deformed by a load, and the piezoelectric sensor is disposed at a distance from the nonlinear flexure member via at least a deformation means, and a load is applied. A pressure-sensitive sensor, wherein the piezoelectric sensor is configured to be deformed before the non-linear flexible member, and then the non-linear flexible member is deformed.   4. The deformation means according to claim 3, wherein the deformation means has a hollow portion at least on the side that receives a load from the non-linear bending member, and is formed so that at least one of the non-linear bending member and the piezoelectric sensor is easily deformed. Pressure sensitive sensor.   The pressure-sensitive sensor according to any one of claims 1 to 4, wherein the non-linear flexible member is formed of a thin elastic body formed in a band shape and having a convex portion.   6. The pressure-sensitive sensor according to claim 5, wherein the convex portion side of the nonlinear flexible member is a load receiving side, and the piezoelectric sensor is disposed on the convex portion side of the nonlinear flexible member.   A pressure-sensitive sensor according to any one of claims 1 to 6, and a determination unit that determines contact of an object with the pressure-sensitive sensor based on an output signal of a piezoelectric sensor disposed in the pressure-sensitive sensor. Touch detection device.   The contact detection apparatus according to claim 7, wherein the determination unit determines whether or not an object continues to contact the pressure sensor based on an output signal of the piezoelectric sensor.   The contact detection device according to claim 7 or 8, wherein the pressure-sensitive sensor is disposed in an opening / closing part of a vehicle or a building, and the determination unit determines whether an object is caught in the opening / closing part based on an output signal of the piezoelectric sensor.   9. The contact detection according to claim 7, wherein the pressure-sensitive sensor is disposed on a bumper of a moving body such as an automatic transport vehicle, and the determination unit determines whether or not the moving body is in contact with an object based on an output signal of the piezoelectric sensor. apparatus.   9. The pressure sensitive sensor is disposed in a living place such as a chair, a seat, a bedding, a bathtub, a toilet seat, and a floor, and the determination unit determines the presence or absence of a human body in the living place based on an output signal of the piezoelectric sensor. The contact detection apparatus as described.

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