JP2005175043A - Polarization device and polarization method of cable-like pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to polarize a flexible pressure sensitive body even if there is a small defect. <P>SOLUTION: A polarization device for a cable-like pressure sensor comprises the flexible pressure sensitive body 12 put around a core electrode 11, a conductor 17 having air holes 16 and a passage 15 for the flexible pressure sensitive body 12 to pass through, a DC voltage generating means 19 connected to the core electrode 11 and the conductor 17, and a current detecting means 20 for detecting a value of current in the core electrode 11 and in the conductor 17. Due to this structure, even if there is a defective portion, a failure of polarizing a flexible piezoelectric body as a whole can be prevented and the defective part and a polarized state of the flexible piezoelectric body can be grasped by means of the current detecting means, making it possible to polarize the flexible piezoelectric body under constant conditions and hence increasing an yield. By forming the air holes 16 in the conductor, attachment of residual volatile components to the conductor 17 can be prevented, resulting in stable polarization. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polarization device for a cable-shaped pressure sensor and a polarization method thereof.

Conventionally, this type of cable-type pressure sensor is shown in FIG. 7 (see, for example, Patent Document 1). As shown in FIG. 7, a flexible pressure-sensitive body 2 is arranged around the core electrode 1, and an outer electrode 3 and an outer skin 4 are sequentially covered around the flexible pressure-sensitive body 2. As the flexible pressure-sensitive body 2, a composite in which ceramic piezoelectric powder of lead titanate and lead zirconate titanate is added to synthetic rubber or synthetic resin is used. The surface is coated with a conductive paint such as silver rubber paint. When a pressure is applied to a part or the whole surface of the cable-shaped pressure sensor, a voltage is induced between the core electrode 1 and the outer electrode 3 as a result of distortion of the pressure sensor of the part, and this induced voltage is used. The pressure is detected. In the polarization method, a high voltage is applied between the core electrode 1 and the outer electrode 3 to polarize the flexible piezoelectric body 2 (see, for example, Non-Patent Document 1). Due to this polarization, the direction of spontaneous polarization of the ceramic particles is aligned with the direction of the electric field, so that piezoelectricity is imparted to the flexible piezoelectric body 4.
JP-A-62-230071 "Piezoelectric composite material consisting of piezoelectric ceramic powder and synthetic rubber" Powder and Industry, Vol. 22, No. 1, 1990, p50 / 56

  However, in the polarization method of the conventional cable-shaped pressure sensor, when a high voltage is applied between the core electrode 1 and the outer electrode 3, there are small cracks or holes in the flexible piezoelectric body 2. When a defect exists, a micro discharge is generated at the defective portion. Due to this minute discharge, the constituent material of the flexible piezoelectric body 2 is thermally evaporated and scattered, the core electrode 1 and the outer electrode 3 are short-circuited, and a high voltage cannot be applied between the core electrode 1 and the outer electrode 3. Therefore, there is a problem that the flexible piezoelectric body 2 cannot be polarized.

  In addition, after the outer electrode 3 is formed on the flexible piezoelectric body 2 and configured as a substantially cable-shaped pressure sensor, the presence of a defect can be detected only by applying a high voltage between the core electrode 1 and the outer electrode 3. Therefore, there was a problem that the yield decreased.

  Further, when the flexible piezoelectric body is heated, volatile components contained in the flexible piezoelectric body adhere to the outer electrode 3, so that efficient polarization cannot be performed, and the voltage concentrates on the attached portion to cause a micro discharge. There was a problem that it was easy.

  An object of the present invention is to solve the above-mentioned conventional problems and to provide a cable-shaped pressure sensor having stable characteristics.

  In order to solve the above-described conventional problems, a polarization device for a cable-shaped pressure sensor according to the present invention is configured to detect a direct current voltage generating means connected to the core electrode and a conductor, and a current value flowing through the core electrode and the conductor. And current detecting means.

  As a result, the conductor acts as an outer electrode, so that a DC voltage is applied between the core electrode and the conductor by a DC voltage generating means to polarize the portion of the flexible piezoelectric body disposed on the conductor. . Furthermore, since it is possible to grasp the defect location and polarization state of the flexible piezoelectric body with the current detection means, the flexible piezoelectric body can be polarized under a certain condition.

  In addition, by providing air holes in the conductor, volatile components such as additives contained in the flexible piezoelectric body can be released to the outside air, so that adhesion of volatile component residues to the conductor can be prevented. The characteristics are stable.

  The cable-shaped pressure sensor according to the present invention prevents the entire flexible piezoelectric body from being polarized even if there is a defect portion, and a minute defect has a certain length before the outer electrode layer or the outer electrode is formed. By detecting the presence within the range by the current detection means, it is possible to grasp the defective portion and polarization state of the flexible piezoelectric body, and to improve the yield.

  Further, by providing an air hole in the conductor, it is possible to prevent the residue of the volatile component from adhering to the conductor and to stably polarize the conductor.

  According to a first aspect of the present invention, there is provided a flexible pressure-sensitive body that is provided around, a conductor that forms a passage for the flexible pressure-sensitive body and has air holes, and a DC voltage generating means that is connected to the core electrode and the conductor. And a polarization device for a cable-shaped pressure sensor comprising the core electrode and a current detection means for detecting a current value flowing through the conductor, so that the current detection means can detect a defective portion or polarization state of the flexible piezoelectric body. Since it can be grasped, it is possible to prevent the entire flexible piezoelectric body from being polarized even if a defect exists, and a minute defect exists within a certain length range before forming the outer electrode. By detecting this, the yield can be improved. Further, by providing an air hole in the conductor, it is possible to prevent the residue of the volatile component from adhering to the conductor and to stably polarize the conductor.

  According to a second aspect of the present invention, in particular, in the first aspect of the present invention, there is provided stop means for determining that the flexible piezoelectric body is defective if the signal from the current detection means is equal to or greater than a predetermined value and stopping the current voltage generation means. By providing, a cable-shaped pressure sensor having stable characteristics can be realized by visually detecting or removing the discharge portion, and the yield can be improved.

  In particular, the third aspect of the invention described in the first or second aspect of the invention automatically defines the discharge location by providing an abnormal location detection means for marking a defective location by a signal from the current detection means. Thus, a cable-like pressure sensor having stable characteristics can be realized, and the yield can be improved.

  In the fourth invention, in particular, the conductor of any one of the first to third inventions is constituted by a plurality of blocks, and the current flowing between each block and the core electrode is detected by the current detection means. It is possible to automatically detect the discharge location with high accuracy, improve the yield, and realize a cable-like pressure sensor having stable characteristics.

  In the fifth aspect of the invention, in particular, the temperature of the flexible piezoelectric body is controlled by providing heating means for heating the flexible pressure sensitive body in the polarization device of any one of the first to fourth aspects of the invention. And efficient polarization is possible, so that the yield can be improved.

  The sixth invention can be automated by improving the yield by providing a moving means for moving the flexible piezoelectric body in the polarization device of any one of the first to fifth inventions.

  In the seventh invention, in particular, when the flexible piezoelectric body is disposed in the passage provided in the conductor, and the flexible piezoelectric body is stationary or moved by the moving means, the flexible piezoelectric body is provided. This is a method in which a DC voltage is applied between the core electrode and the conductor to polarize the electrode, preventing the entire flexible piezoelectric body from being polarized even if a defect exists, By detecting that a minute defect exists within a certain length range before forming the electrode, the yield can be improved.

  The eighth invention is a polarization method for a cable-shaped pressure sensor provided with a heating means for heating a flexible piezoelectric body in particular, and can provide a highly reliable cable-shaped pressure sensor.

  The ninth aspect of the invention is a polarization method in which a core electrode of a flexible piezoelectric body is set to ground potential and a DC voltage is applied between the core electrode and a conductor, and a DC high voltage portion that is dangerous to the human body is provided. Since it can limit to a conductor, the safety | security with respect to a human body can be ensured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is an external sketch showing the configuration of a polarization device for a cable-shaped pressure sensor according to Embodiment 1 of the present invention.

  In FIG. 1, the cable-shaped pressure sensor is formed with a flexible pressure-sensitive body 12 that is provided around the core electrode 11. As the core electrode 11, a coiled metal wire, a wire bundled with fine metal wires, or the like is used. As the flexible piezoelectric body 12, a polymer material such as lead zirconate titanate is used as a polymer base material such as an epoxy resin, a urethane resin, a chloroprene resin, a chlorinated polyethylene, or a silicon resin. The flexible piezoelectric body 12 has a passage 15 for the flexible piezoelectric body 12 and is disposed on a conductor 17 having an air hole 16 formed therein. As the conductor 17, a conductor such as iron, stainless steel, copper, brass, or aluminum is used. There is no problem as long as the passage 15 of the flexible piezoelectric body 12 has a shape that allows the flexible piezoelectric body 12 to pass, such as a circle, an ellipse, and a rectangle. The passage 15 was formed by cutting, polishing, electric discharge, extrusion, forging, and pressing. In the embodiment of the present invention, the conductor 17 is made of aluminum, and the shape of the passage 15 is circular. By making it circular, a DC voltage can be uniformly applied to the flexible piezoelectric body 12, and stable sensor characteristics can be obtained. Specifically, a circular hole having a diameter of 4 mm was provided in the conductor 17 as a passage 15 for the flexible piezoelectric body 12 having an outer diameter of 2 mm. Furthermore, the conductor 17 is provided with an air hole 16 through which volatile components such as additives generated from the flexible piezoelectric body 12 are released to the outside air when polarized or heated. In the present embodiment, the air holes 16 have a mesh shape. In particular, by making the mesh shape, the state of polarization of the flexible piezoelectric body 12 can be seen from the outside. Therefore, even if a failure occurs, the failure portion can be easily found.

  The conductor 17 is electrically connected by a lead wire 18b. The lead wire 18a is electrically connected to the positive or negative electrode of the DC voltage generating means 19, and the core electrode 11 is electrically connected to the other pole of the DC voltage generating means 19 via the lead wire 18a. Since the flexible piezoelectric body 12 is connected in this way and a high voltage is applied between the core electrode 11 and the conductor 17 by the DC voltage generating means 19, the flexible piezoelectric body 12 is polarized. The current flowing through the flexible piezoelectric body 12 during polarization, that is, the value of the current flowing between the core electrode 11 and the conductor 17 is detected by the current detection means 20.

  In the present embodiment, polarization was performed at an applied voltage of 8 kv / mm. In particular, by applying a DC voltage between the core electrode 11 and the conductor 17 by setting the core electrode 11 of the flexible piezoelectric body 12 to the ground potential, the DC high voltage portion dangerous to the human body is limited to the conductor 17. Safety to the human body can be ensured.

  When a minute defect is included in the flexible piezoelectric member 12 and the portion is disposed on the conductor 17, a high current is generated between the conductor 17 and the core electrode 11 due to a minute discharge generated in the defect portion. It cannot be polarized due to current flow and short circuit. However, if the defective portion is detached from the conductor 17 and there is no defect in the flexible piezoelectric body 12 disposed on the conductor 17, the insulation between the conductor 17 and the core electrode 11 is restored again. , Polarization becomes possible. As described above, according to the polarization device of the present invention, polarization cannot be performed only when a portion including a defect is disposed on the conductor 17, but polarization is possible in other cases. Therefore, the flexible piezoelectric body 12 cannot be polarized throughout due to the presence of defects.

  Further, since the discharge can be detected by a signal from the current detection means 20 that detects the current flowing between the core electrode 11 and the conductor 17, the presence of a defect in the flexible piezoelectric body 12 at that time can be detected. Can do. Therefore, since it can be detected that a defect exists in the flexible piezoelectric body 12 having a certain length before the outer electrode 13 is formed, the defect portion can be easily removed after the cable-shaped pressure sensor is completed.

  Furthermore, even if no discharge is performed, if there is a defect such as a minute crack in the flexible piezoelectric body 12, the current flowing through the flexible piezoelectric body 12 increases. That is, the state of the flexible piezoelectric body 20 can be grasped by the signal of the current detection means 20.

  In addition, since part of the flexible piezoelectric body 12 is exposed to a high temperature when discharged, volatile components such as additives contained in the flexible piezoelectric body 12 may evaporate. At this time, if there is no air hole 16, it adheres to the flexible piezoelectric body 12 side of the passage 15 of the conductor 17. As a result, the voltage applied from the DC voltage generating means 19 is applied to the flexible piezoelectric body 12 via the deposit, and the voltage actually applied to the flexible piezoelectric body 12 may be reduced. In addition, there is a possibility that a stable polarization cannot be performed due to a difference from a portion having no deposit. However, in the present invention, since the air hole 16 is provided, even if a volatile component is generated, it escapes to the outside air through the air hole 16, so that the voltage is stably applied without adhering in the passage 15. be able to.

  Further, as shown in FIG. 2, if a signal from the current detection means 20 is equal to or greater than a predetermined value, a stop means 21 for stopping the current voltage generation means 19 is provided, so that a defective part is visually detected during the polarization process. Alternatively, it can be removed, the production can be stabilized, and the yield can be improved.

  In this embodiment, the conductor 17 and the passage 15 are circular. However, the conductor 17 and the passage 15 are formed in a concave shape, and a conductive plate provided with an air hole 16 is provided as a lid on the upper portion of the concave conductor 17. The same effect can be obtained even if it is disposed.

(Embodiment 2)
FIG. 3 is a cross-sectional view of a main part of the cable-shaped pressure sensor according to Embodiment 2 of the present invention. In FIG. 3, the difference from the first embodiment is that an abnormal point detection unit 22 that marks a discharge point by a signal from the current detection unit 20 is provided. The same members as those in the first embodiment are given the same reference numerals.

  In the present embodiment, the abnormal location detection means 22 determines that there is a discharge location in the flexible piezoelectric body 12 disposed on the conductor 17 based on a signal from the current detection means 20, and applies ink or the like. To mark. By providing the abnormal part detecting means 22, the defective part can be automatically clarified and the defective part can be easily removed later, so that the manufacturing efficiency and the yield can be improved.

  In this embodiment, the defective portion is marked with ink, but the present invention is not limited to this as long as the defective portion becomes clear.

(Embodiment 3)
FIG. 4 is a cross-sectional view of a main part of the cable-shaped pressure sensor according to Embodiment 3 of the present invention. In FIG. 4, the difference from Embodiments 1 and 2 is that the conductor 17 is composed of a plurality of blocks 23, and the current flowing between each block 23 and the core electrode 11 is detected by the current detection means 20. Is a point. The same members as those in the first embodiment are given the same reference numerals.

  With this configuration, even if a micro discharge occurs, it is possible to detect in which block 23 the micro discharge has occurred by detecting the current flowing between each block 23 and the core electrode 11 with the current detection means 20. . For this reason, the defective part of the flexible piezoelectric body 12 can be easily identified with high accuracy. Further, by applying ink or the like with the abnormal part detection means 22 and marking it, a defective part which is a discharge part can be automatically clarified, and a cable-like pressure sensor having a stable characteristic while improving the yield is provided. Can be realized.

  In this embodiment, the defective portion is marked with ink, but the present invention is not limited to this as long as the defective portion becomes clear.

(Embodiment 4)
FIG. 5 is a cross-sectional view of a main part of the cable-shaped pressure sensor according to Embodiment 4 of the present invention. In FIG. 5, the difference from Embodiments 1 to 3 is that a heating means 24 for heating the flexible pressure sensitive body is provided. The same members as those in the first embodiment are given the same reference numerals.

  As shown in FIG. 4, in the present embodiment, the heating means 24 is constituted by a heater that heats the conductor 17.

  The temperature at which the flexible piezoelectric body 12 is polarized is preferably higher than the temperature at which it is used. This is because the polymer, additive, and the like constituting the flexible piezoelectric body 12 are thermally expanded and compositionally deformed by heat, and the direction of spontaneous polarization aligned by the polarization is shifted, so that the piezoelectric characteristics may be deteriorated. . For this reason, a cable-shaped pressure sensor with high reliability can be realized by appropriately holding and polarizing the temperature of the flexible piezoelectric body 12 by the heating means 24.

  Further, when polarized at a high temperature, volatile components such as additives contained in the flexible piezoelectric body 12 may evaporate. At this time, when there is no air hole 16, it may adhere to the flexible piezoelectric body 12 side of the passage 15 of the conductor 17. However, since the polarization device of the present invention has the air hole 16, the volatile component is not present. Even if it occurs, it escapes to the outside air through the air holes 16, so that the voltage can be stably applied without adhering to the passage 15.

  Although a heater for heating the conductor 17 is used as the heating means 24 in the embodiment of the present invention, the same effect can be obtained by heating the flexible piezoelectric body 12 by generating hot air and circulating it in the passage. can get.

(Embodiment 5)
FIG. 6 is an external view of a main part of a cable-shaped pressure sensor according to Embodiment 5 of the present invention. In FIG. 6, the difference from the first to fourth embodiments is that a moving means 25 for moving the flexible piezoelectric body 12 is provided. The same members as those in the first and second embodiments are given the same reference numerals.

  As shown in FIG. 6, the flexible piezoelectric body 12 is disposed on the conductor 17, and a rotating drum is used as the moving means 25 for moving. By changing the rotation speed of the rotating drum, it is possible to easily adjust the time for which the flexible piezoelectric body 12 is disposed in the conductor 17, in other words, the polarization time. Further, by providing the moving means 25, it is possible to automate, so that the yield can be improved.

  As described above, the polarization device of the cable-shaped pressure sensor and the polarization method according to the present invention prevent the entire flexible piezoelectric body from being unable to polarize even if a defect exists, Before forming the outer electrode layer or the outer electrode, it is possible to improve the yield by detecting the presence of minute defects within a certain length range, and to reduce the residual volatile component to the conductor. It is a polarization device that can prevent adhesion and can be stably polarized. For this reason, it is applicable not only to a cable-shaped pressure sensor but also to a piezoelectric body that requires polarization.

FIG. 1 is an external perspective view showing a configuration of a polarization device in Embodiment 1 of the present invention. External perspective view showing another configuration of the polarization device External appearance perspective view which shows the structure of the polarization apparatus in Embodiment 2 of this invention. External appearance perspective view which shows the structure of the polarization apparatus in Embodiment 3 of this invention. External appearance perspective view which shows the structure of the polarization apparatus in Embodiment 4 of this invention. External appearance perspective view which shows the structure of the polarization apparatus in Embodiment 5 of this invention. External perspective view showing the configuration of a conventional polarization device

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Core electrode 12 Flexible pressure sensitive body 13 External electrode 14 Outer skin 15 Passage 16 Air hole 17 Conductor 18 Lead wire 19 DC voltage generation means 20 Current detection means 21 Stop means 22 Abnormal location detection means 23 Block 24 Heating means 25 Movement means

Claims (10)

A flexible pressure-sensitive body provided around the core electrode; a conductor that forms a passage of the flexible pressure-sensitive body and has air holes; and a DC voltage generating means connected to the core electrode and the conductor; A polarization device for a cable-shaped pressure sensor, provided with the core electrode and a current detection means for detecting a current value flowing through the conductor. 2. The polarization device for a cable-like pressure sensor according to claim 1, further comprising a stopping unit that determines that the flexible piezoelectric body is defective if the signal from the current detecting unit is equal to or greater than a predetermined value and stops the current-voltage generating unit. . The polarization device for a cable-like pressure sensor according to claim 1 or 2, further comprising an abnormal point detection unit for marking a defective portion by a signal from the current detection unit. The polarization device for a cable-shaped pressure sensor according to any one of claims 1 to 3, wherein the conductor is composed of a plurality of blocks, and a current flowing between each block and the core electrode is detected by a current detection means. An abnormality location detection means is provided for determining that the flexible piezoelectric body is defective if the signal from the current detection means is equal to or greater than a predetermined value, and marking the flexible piezoelectric body in the block. 5. A polarization device for a cable-shaped pressure sensor according to 4. The polarization device for a cable-shaped pressure sensor according to any one of claims 1 to 5, further comprising heating means for heating the flexible pressure sensitive body. The polarization device for a cable-shaped pressure sensor according to any one of claims 1 to 6, further comprising a moving means for moving the flexible piezoelectric body. A flexible piezoelectric body is disposed in a passage provided in the conductor, and when the flexible piezoelectric body is stationary or moved by a moving means, the core electrode of the flexible piezoelectric body and the conductor A polarization method for a cable-type pressure sensor in which a DC voltage is applied between the two. 9. The method for polarizing a cable-shaped pressure sensor according to claim 8, further comprising a heating means for heating the flexible piezoelectric body. The polarization method for a cable-shaped pressure sensor according to claim 8 or 9, wherein a core voltage of the flexible piezoelectric body is set to a ground potential, and a DC voltage is applied between the core electrode and the conductor.

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