JP2003294549A - Cable type piezoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that a concrete and reliable constitution for connecting a resistance for disconnection detection to a piezoelectric sensor is not expressed clearly on a conventional piezoelectric sensor, and that insertion is difficult when inserting the piezoelectric sensor into an inner hole provided in a rubber member because a printed circuit board becomes larger than the outer diameter of the piezoelectric sensor even if the printed circuit board is used when fixing the resistance. <P>SOLUTION: A resistor 5 having the size smaller than the outer diameter of the piezoelectric sensor is connected between a core electrode 1 and an outside electrode 3, to thereby enable the outer diameter of a terminal part to be the same as or smaller than the outer diameter of the piezoelectric sensor, and hereby the piezoelectric sensor can be easily inserted and fixed in the inner hole of the mounting rubber member. Besides, a constitution wherein the long axis direction of the resistor 5 is squared with the coaxial direction of the core electrode 1, and one lead wire 6a of the resister is connected to the core electrode 1, and the other lead wire 6b is folded back and connected to the outside electrode 3, namely, the concrete and reliable constitution for connecting the resistance for disconnection detection to the piezoelectric sensor is provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable-shaped piezoelectric sensor.

[0002]

2. Description of the Related Art Conventionally, a cable-shaped piezoelectric sensor has the following structure. That is, as shown in FIG. 5, the flexible composite piezoelectric layer 2 is formed on at least the surface of the flexible core electrode 1 forming the internal electrode, and the surface of the flexible composite piezoelectric layer 2 is covered. And the conductive tape 3 forming the outer electrode. In other words, the cable-shaped piezoelectric sensor has the flexible composite piezoelectric layer 2 formed by the composite piezoelectric material in which the synthetic resin and the ceramic piezoelectric powder are mixed around the flexible core electrode 1 forming the internal electrode. It is formed by spirally winding a conductive tape 3 in the form of an extrusion film. Then, when pressure is applied from the outside to deform, stress is applied to the piezoelectric ceramic existing in the flexible composite piezoelectric layer 2, and a voltage is induced between the core electrode 1 and the conductive tape 3. Therefore, the pressure is detected by the voltage. At this time, the conductive tape 3 is in close contact with the flexible composite piezoelectric layer 2 and functions as a stable outer electrode.

Such a piezoelectric sensor is usually used by being arranged on a flexible resin member, preferably a rubber member, in order to enhance sensitivity. Specifically, the piezoelectric sensor is used by inserting it into a rubber member having an inner hole. As an application, for example, it is provided in a window frame of an automobile and used as a sensor for preventing a power window from being caught, or as a sensor for detecting a collision of a moving body.

A signal processing circuit for detecting a voltage signal from the piezoelectric sensor is disclosed in, for example, Japanese Patent Laid-Open No. 10-76843.
It is disclosed in the publication. FIG. 6 shows an example of the circuit diagram. In the figure, Ps is a piezoelectric sensor, and R1 is a resistor for detecting disconnection, which is connected between the electrodes of the piezoelectric sensor. R1 is connected to the power supply Vd via another resistor R2. R3, R
Reference numeral 4 is a resistor for deriving a signal from the piezoelectric sensor, and Q1 is an FET for impedance conversion.

The resistance R1 for detecting disconnection is provided at the tip end opposite to the one connected to the signal processing circuit, for detecting disconnection when the cable-shaped piezoelectric sensor is accidentally cut by a cutting tool. Installed on. Then, the voltage value V formed by R1, R2, R3 and Vd in the signal processing circuit
The disconnection was detected by monitoring 1. When the piezoelectric sensor is used for the above-mentioned applications, the disconnection detection improves reliability.

[0006]

However, the conventional piezoelectric sensor described above has a problem in that a specific and reliable structure for connecting a resistance for detecting disconnection to the piezoelectric sensor has not been clearly indicated.

Further, for example, when a printed circuit board is used for mounting a resistor, the printed circuit board becomes larger than the outer diameter of the piezoelectric sensor, and as described above, the piezoelectric sensor tries to be inserted into the inner hole provided in the rubber member. Also becomes difficult to insert. Therefore, it takes time and effort to insert the piezoelectric sensor into the rubber member before attaching the resistor and then attach the printed circuit board with the resistor to the end of the piezoelectric sensor, which is a mounting problem.

The present invention has been made to solve the above-mentioned problems of the prior art by clearly showing a concrete and reliable structure for connecting a resistance for wire breakage detection to a piezoelectric sensor and connecting a resistance for wire breakage detection. However, it is an object of the present invention to provide a piezoelectric sensor that can be easily mounted.

[0009]

In order to solve the above-mentioned problems, the present invention provides a cable-shaped piezoelectric sensor in which the outer diameter of the piezoelectric sensor is equal to or smaller than the outer diameter of the piezoelectric sensor between the core electrode and the outer electrode in the terminal portion of the piezoelectric sensor. By connecting a resistor of size, the outer diameter of the terminal can be made the same as or less than the outer diameter of the piezoelectric sensor.
When the piezoelectric sensor is attached to the rubber member for mounting the piezoelectric sensor, since the terminal portion can be passed through the inner hole of the rubber member, the manufacturing process can be simplified.

Further, the cable-shaped piezoelectric sensor of the present invention is
The outer electrode is at ground potential, the major axis direction of the resistor is aligned with the core electrode, and one lead wire of the resistor is connected to the core electrode, and the other lead wire is folded back and connected to the outer electrode. With the configuration, it is possible to provide a specific and reliable configuration in which a resistor for detecting disconnection is connected to the piezoelectric sensor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a terminal portion of a piezoelectric sensor, in which a resistor having a size equal to or smaller than the outer diameter of the piezoelectric sensor is connected between the core electrode and the outer electrode. Since the outer diameter of can be made the same as or smaller than the outer diameter of the piezoelectric sensor, the terminal part can be passed through the inner hole of the rubber member when mounting the piezoelectric sensor on the rubber member for mounting the piezoelectric sensor. Can be simplified.

The invention according to claim 2 uses a resistor having lead wires at both ends as the resistor according to claim 1, and is practically used as a resistor connectable to a core wire of a piezoelectric sensor and an outer electrode. Specific configuration can be provided.

According to a third aspect of the invention, in the first or second aspect of the invention, the outer electrode is at ground potential, and the major axis direction of the resistor is aligned with the core electrode in the coaxial direction. One lead wire is connected to the core electrode, the other lead wire is folded back and connected to the outer electrode, providing a concrete and reliable structure for connecting a resistance for disconnection detection to the piezoelectric sensor You can do it.

According to a fourth aspect of the present invention, the resistor according to any one of the first to third aspects is covered with a conductor having a ground potential, and the resistor and the resistor and the core wire are combined. It is possible to prevent the influence of noise on the connecting portion and the like.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the outer electrode is at ground potential, and the long axis direction of the resistor is aligned with the core electrode in the coaxial direction. One of the lead wires is connected to the core electrode, and the other lead wire is connected to a conductor having a ground potential that covers the resistor body. Specifically, a resistance for disconnection detection is connected to the piezoelectric sensor. In addition, it is possible to provide a reliable structure, and it is possible to prevent the influence of noise on the resistor and the connection between the resistor and the core wire.

According to a sixth aspect of the present invention, the conductor according to the fourth or fifth aspect is molded into a cap shape and can be fitted into an end of a piezoelectric sensor to which a resistor is connected. The conductor is a cap. Since it is molded into a shape, the piezoelectric sensor can be easily passed through the inner hole of the rubber member.

According to a seventh aspect of the present invention, the conductor according to the fifth aspect is formed into a cap shape and can be fitted into an end portion of a piezoelectric sensor to which a resistor is connected, and the side where the piezoelectric sensor is fitted. Has a through hole capable of penetrating the lead wire of the resistor at the opposite end, and the conductor and the lead wire can be crimped by the through hole, and the conductor is formed into a cap shape. Therefore, the piezoelectric sensor can be easily passed through the inner hole of the rubber member, and the lead wire of the resistor can be penetrated through the through hole to crimp the conductor and the lead wire. There is no need to fold the wire, and the resistor mounting can be simplified.

The invention described in claim 8 is the one in which the conductor according to claim 4 or 5 is connected to the outer electrode, and it is possible to provide a specific configuration in which the conductor is set to the ground potential.

According to a ninth aspect of the present invention, in the invention according to any one of the third to sixth aspects, the connecting portion between the lead wire of the resistor and the core electrode and its vicinity are electrically insulated. Is.

The invention according to a tenth aspect is the second to fifth aspects.
In the invention described in any one of 1, the one lead wire of the resistor and the core electrode are connected by at least one method of welding, brazing, and caulking with a caulking member.

The invention described in claim 11 is the invention according to claims 2 to 6.
In the invention described in any one of 1, the one lead wire of the resistor and the outer electrode are connected by at least one method of processing by welding, brazing, or caulking with a caulking member.

[0022]

Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is an external perspective view showing the structure of a cable-shaped piezoelectric sensor according to a first embodiment of the present invention. A flexible composite piezoelectric layer 2 is formed on the surface of a flexible core electrode 1 forming an internal electrode, and a conductive tape 3 covering the surface of the flexible composite piezoelectric layer 2 to form an outer electrode.
Then, a protective coating layer 4 is further formed around it.

As the core electrode 1, a coiled metal wire or a wire obtained by bundling fine metal wires can be used. In this embodiment, a stainless stranded wire having an outer diameter of 0.3 mm is used.

As the flexible composite piezoelectric layer 2, a composite piezoelectric material obtained by adding a ceramic piezoelectric powder such as lead zirconate titanate to a polymer base material such as epoxy resin, urethane resin, chloroprene resin, chlorinated polyethylene resin. Or P
A polymer piezoelectric material such as VDF is used, and in the present embodiment, the outer diameter is 1.7 mm, which is formed by coating.

As the conductive tape 3, a copper foil, an aluminum foil, a PET film on which aluminum is vapor deposited, or the like is used. In this embodiment, an Al-PET-Al three-layer laminated film having a width of 3 mm is spirally wound. As the protective coating layer 4, vinyl chloride, fluororesin, polyurethane or the like is used. In this embodiment, vinyl chloride is coated and molded to have an outer diameter of 2.5 mm.

The major axis direction and the lead wire direction of the resistor 5 are aligned with the core electrode coaxial direction, the lead wire 6a on the side close to the piezoelectric sensor is connected to the core electrode 1, and the lead wire 6b is folded back on the opposite side to conduct electricity. To the sex tape 3. As a result, the resistor 5 is arranged so that it is smaller than the outer diameter of the protective coating layer 4 and the electrically exposed portions of the lead wire 6a and the core electrode 1 are reduced. The resistor 5 may be a chip resistor, a resistor with a lead wire, or the like as long as the outer diameter is smaller than the protective coating layer 4,
In the present embodiment, a 1/4 W lead wire coating resistor in which lead wires are integrated is used.

The lead wire 6a and the core electrode 1 are electrically connected by welding, brazing, caulking or the like, and the lead wire 6b and the conductive tape 3 are electrically connected by welding, brazing or caulking. Connected. An insulating coating 7 is formed on the surface of the lead wire 6b to prevent a short circuit with the lead wire 6a. The insulating coating 7 is made of vinyl chloride, fluororesin, polyurethane, or the like. Insulation coating 7 is lead wire 6
It may be molded on the side of a.

Finally, a heat-shrink tube 8 is arranged around the resistor 5 to protect it. The heat-shrinkable tube 8 may be replaced with epoxy, silicon, hot melt or the like as long as it is an insulator.

With the above structure, the outer diameter of the terminal portion can be made equal to or smaller than the outer diameter of the piezoelectric sensor. Therefore, when the piezoelectric sensor is mounted on the rubber member for mounting the piezoelectric sensor, the terminal portion is covered by the rubber member 9. Since it can be passed through the hole, the manufacturing process can be simplified.

Further, a resistor having lead wires at both ends can be used as the resistor, and a practical structure can be provided as a resistor connectable to the core wire of the piezoelectric sensor and the outer electrode.

Further, the outer electrode is at earth potential, the long axis direction of the resistor is aligned with the core electrode coaxially, one lead wire of the resistor is connected to the core electrode, and the other lead wire is folded back. With the structure connected to the outer electrode, it is possible to provide a concrete and reliable structure in which a resistance for disconnection detection is connected to the piezoelectric sensor.

(Embodiment 2) FIG. 2 is an external perspective view showing the structure of a cable-shaped piezoelectric sensor according to a second embodiment of the present invention. This embodiment is different from the first embodiment in that the resistor 5
Is covered with a metal sleeve 10 as a conductor, and the metal sleeve 10 is connected to a conductive tape 3 as an outer electrode having a ground potential.

The metal sleeve 10 may be made of any material such as copper and aluminum as long as it is conductive, and may be wrapped with copper foil, aluminum foil or the like to replace the sleeve. The conductive tape 3 is at ground potential, and the metal sleeve 10 and the conductive tape 3 are electrically connected to each other, so that the metal sleeve 10 becomes at ground potential. As a result, the metal sleeve 10 can protect the resistor 5 and can also serve as a shield for the resistor 5 to reduce the influence of noise on the resistor 5 and the connection between the resistor and the core wire.

(Embodiment 3) FIG. 3 is an external perspective view showing the structure of a cable-shaped piezoelectric sensor according to a third embodiment of the present invention. This embodiment is different from Embodiments 1 and 2 in that the conductive tape 3 as the outer electrode is at the ground potential, the major axis direction of the resistor 5 is aligned with the core electrode 1 in the coaxial direction, and One of the lead wires 6a is connected to the core electrode 1, and the other lead wire 6b is connected to a cap-shaped conductor 11 having a ground potential for covering the resistor 5. The conductor 11
Is a through hole that can be fitted into the end 12 of the piezoelectric sensor on the side to which the resistor 5 is connected, and through which the lead wire 6b of the resistor 5 can penetrate through the end 13 opposite to the side on which the piezoelectric sensor is fitted. 14 is provided, and the conductor 11 and the lead wire 6b can be crimped by the through hole 14. Further, the connection between the conductor 11 and the conductive tape 3 as the outer electrode is
By pressing the conductor 11 at the K1 position, the conductor 11 is pressed.
Presses onto the conductive tape 3.

With the above structure, the outer electrode is at the ground potential, the long axis direction of the resistor is aligned with the core electrode,
Since one lead wire of the resistor is connected to the core electrode and the other lead wire is connected to a conductor having a ground potential for covering the resistor, as in Examples 1 and 2,
It is possible to provide a concrete and reliable configuration in which a resistance for disconnection detection is connected to the piezoelectric sensor, and it is possible to prevent the influence of noise on the resistor or the connection between the resistor and the core wire. .

Further, since the conductor is formed in the shape of a cap, the piezoelectric sensor can be easily passed through the inner hole of the rubber member, and the lead wire of the resistor is passed through the through hole to cause the conductor to pass through. Since the lead wire and the lead wire can be crimped together, it is not necessary to fold the lead wire, and the mounting of the resistor can be further simplified.

As shown in FIG. 4, the resistor 5 is previously arranged inside the conductor 11, and the core electrode 1 and the lead wire 6 are provided.
When connecting a, the insulator 15 and the caulking member 16 may be used to pressurize the conductor 11 at the position K2 to connect the core electrode 1 and the lead wire 6a by caulking.

Further, although the present invention provides a concrete structure in which a resistor for detecting disconnection is connected to the end of the cable-shaped piezoelectric sensor, when detecting disconnection of another cable-shaped sensor or cord. Also, a configuration similar to the resistor connection configuration of the present invention may be used.

[0040]

As described above, according to the cable-shaped piezoelectric sensor of the present invention, in the terminal portion of the piezoelectric sensor,
A resistor with a size smaller than the outer diameter of the piezoelectric sensor can be connected between the core electrode and the outer electrode, and the outer diameter of the terminal can be made the same as or smaller than the outer diameter of the piezoelectric sensor. When the sensor is attached, the terminal portion can be passed through the inner hole of the rubber member, so that the manufacturing process can be simplified.

According to the cable-shaped piezoelectric sensor of the present invention, the outer electrode is at ground potential, the major axis direction of the resistor is aligned with the core electrode in the coaxial direction, and one lead wire of the resistor is the core electrode. , And the other lead wire is folded back and connected to the outer electrode. Therefore, it is possible to provide a concrete and reliable structure in which a resistor for detecting disconnection is connected to the piezoelectric sensor.

[Brief description of drawings]

FIG. 1 is an external perspective view showing a configuration of a cable-shaped piezoelectric sensor according to a first embodiment of the present invention.

FIG. 2 is an external perspective view showing the configuration of a cable-shaped piezoelectric sensor according to a second embodiment of the present invention.

FIG. 3 is an external perspective view showing the configuration of a cable-shaped piezoelectric sensor according to a third embodiment of the present invention.

FIG. 4 is an external perspective view showing the configuration of a cable-shaped piezoelectric sensor according to another embodiment of the present invention.

FIG. 5 is an external perspective view showing the configuration of a conventional cable-shaped piezoelectric sensor.

FIG. 6 is a circuit diagram for detecting disconnection of a conventional cable-shaped piezoelectric sensor.

[Explanation of symbols]

1-core electrode 2 Flexible composite piezoelectric layer (piezoelectric) 3 Conductive tape (outer electrode) 5 resistor 6a lead wire 6b lead wire 10 Metal sleeve (conductor) 11 conductor 14 through holes 16 caulking member

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Ogino             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (11)

[Claims] 1. A cable-shaped piezoelectric sensor, comprising: a core electrode; a piezoelectric body arranged around the core electrode; and an outer electrode arranged around the piezoelectric body. A cable-shaped piezoelectric sensor, comprising a terminal portion in which a resistor having a size equal to or smaller than the outer diameter of the piezoelectric sensor is connected between the core electrode and the outer electrode at either end. 2. The cable-shaped piezoelectric sensor according to claim 1, wherein the resistor is a resistor having lead wires at both ends. 3. The outer electrode is at earth potential, the major axis direction of the resistor is aligned with the core electrode, the one lead wire of the resistor is connected to the core electrode, and the other lead wire is folded back. 3. The structure according to claim 1, wherein the structure is connected to the outer electrode.
The cable-shaped piezoelectric sensor according to 1. 4. The cable-shaped piezoelectric sensor according to claim 1, wherein the resistor is covered with a conductor having a ground potential. 5. The outer electrode is at ground potential, the major axis direction of the resistor is aligned with the core electrode, the one lead wire of the resistor is connected to the core electrode, and the other lead wire is the resistor. The cable-shaped piezoelectric sensor according to claim 1 or 2, wherein the piezoelectric sensor is connected to a conductor having a ground potential that covers the body. 6. The electric conductor is shaped like a cap and can be fitted into the end of the piezoelectric sensor to which the resistor is connected.
Alternatively, the cable-shaped piezoelectric sensor according to item 5. 7. A conductor is formed in a cap shape and can be fitted into an end of a piezoelectric sensor to which a resistor is connected, and a lead wire of the resistor is provided at an end opposite to a side where the piezoelectric sensor is fitted. The cable-shaped piezoelectric sensor according to claim 5, further comprising a through hole through which the conductor and the lead wire can be crimped. 8. The cable-shaped piezoelectric sensor according to claim 4, wherein the conductor has a structure connected to the outer electrode. 9. The connecting part between the lead wire of the resistor and the core electrode and its vicinity are electrically insulated.
The cable-shaped piezoelectric sensor according to claim 1. 10. The resistor according to claim 2, wherein one lead wire of the resistor and the core electrode are connected by at least one method of processing by welding, brazing, or caulking with a caulking member.
The cable-shaped piezoelectric sensor according to item. 11. At least one of one lead wire of the resistor and the outer electrode is welded, brazed, or crimped by a caulking member.
The cable-shaped piezoelectric sensor according to any one of claims 2 to 6, which is connected by one processing method.