JP2008041677A - Polarizing apparatus of pressure sensor, and polarizing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems that an entire flexible pressure-sensitive material cannot be polarized when a slight defect is present in applying high voltage to between a core electrode and an external electrode for polarization and, in addition, that characteristics vary when the flexible pressure-sensitive material is mounted on a passage of a polarized electrode. <P>SOLUTION: The polarized apparatus is provided with the flexible pressure-sensitive material 12 provided around the core electrode 11, a conductor 13 constituted of a plurality of conductive foils to come into contact with the entire circumference of the material 12, a voltage applying means 16 connected with the core electrode 11 and the conductor 13, a heating means 14 for heating the material 12, and a moving means 15 for moving the material 12 while in contact with the conductor 13. The conductor 13 can be uniformly brought into contact with the flexible pressure-sensitive material 12, and therefore uniform and thorough polarization is possible from the entire periphery. Thus, no unpolarized part remains, and stable characteristics can be obtained free from variation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarization device and a polarization method for a pressure sensor.

  Conventionally, there is such a pressure sensor as shown in FIG. 6 (see, for example, Patent Document 1). As shown in FIG. 6, 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, and the outer electrode 3 is made of the flexible pressure-sensitive body 2. The surface is coated with a conductive paint such as silver rubber paint. When a pressure is applied to a part or the entire 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. 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 pressure-sensitive body 2 (see, for example, Non-Patent Document 1). In addition, as shown in FIG. 7, the flexible pressure-sensitive body 2 is disposed in the passage of the block-shaped conductor 5, and a voltage is applied between the block-shaped conductor 5 and the core electrode 1, whereby the block-shaped conductor 5. The portion of the flexible pressure-sensitive body 2 disposed in is polarized (for example, see Patent Document 2). 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 pressure-sensitive body 2.
JP 62-230071 A JP 2002-280633 A "Piezoelectric composite material consisting of piezoelectric ceramic powder and synthetic rubber" Powder and Industry, Vol. 22, No. 1, 1990, p50 / 56

  However, in the conventional pressure sensor polarization method, when a high voltage is applied between the core electrode 1 and the outer electrode 3, there is a defect such as a minute crack or a hole in the flexible pressure-sensitive body 2. A minute discharge occurs at the defective portion. Due to this minute discharge, the constituent material of the flexible pressure-sensitive 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 was a problem that the flexible pressure-sensitive body 2 could not be polarized. In the case where the flexible pressure-sensitive body 2 is disposed on the block-shaped conductor 5 and is polarized while being moved by the moving means 7, the flexible pressure-sensitive body 2 has a cable shape. Therefore, there is a problem that a portion that contacts the block-like conductor 5 and a portion that does not contact are generated, a difference occurs in the degree of polarization, and characteristic variation occurs. Furthermore, even when the flexible pressure-sensitive body 2 is heated by heating the block-shaped conductor 5 by the heating means 6, the flexible pressure-sensitive body 2 has a portion that is not heated, and the temperature There has been a problem that characteristic variations occur due to the distribution.

  The present invention solves the above-described conventional problems, and prevents the entire flexible pressure-sensitive body from being unable to polarize even if a defect exists. In addition, it is intended to obtain a stable characteristic with no characteristic variation by uniformly and evenly polarizing the conductor made of conductive foil so that it is in contact with the entire circumference of the flexible pressure-sensitive body. And

In order to solve the above-described conventional problems, a polarization device for a cable-shaped pressure sensor according to the present invention includes a flexible pressure-sensitive body provided around a core electrode, and a conductive pressure-sensitive body so as to contact the flexible pressure-sensitive body. A conductor made of foil, a voltage applying means connected to the core electrode and the conductor, a heating means for heating the flexible pressure-sensitive body, and the flexible pressure-sensitive body in contact with the conductor By providing the moving means that moves while moving, it is possible to uniformly contact the conductor with the flexible pressure-sensitive body, and thus it is possible to uniformly polarize the entire circumference. For this reason, there are no unpolarized portions, and stable characteristics without characteristic variations can be obtained. In addition, since the entire circumference of the flexible pressure sensitive body can be moved while being in contact with the conductor in a state where the contact resistance with the flexible pressure sensitive body is reduced, the productivity is improved. While improving, the damage of the flexible pressure sensitive body which arises by contact resistance can also be prevented.

  The cable-shaped pressure sensor of the present invention can prevent the flexible pressure-sensitive body of the entire long cable from being unable to polarize even if a defect exists. Furthermore, by configuring the conductor made of conductive foil so as to be in contact with the entire circumference of the flexible pressure-sensitive body, it can be uniformly polarized evenly and stable characteristics without characteristic variation can be obtained. . In addition, the entire circumference of the flexible pressure sensitive body can be moved in the passage in a state in which the contact resistance with the flexible pressure sensitive body is reduced, rather than closely contacting with the polarization electrode, and productivity can be improved. It is also possible to prevent damage to the flexible pressure-sensitive body caused by contact resistance, deformation due to heat accumulation, and change in composition.

  A conductor composed of a first foil, a voltage applying means connected to the core electrode and the conductor, a heating means for heating the flexible pressure sensitive body, and the flexible pressure sensitive body A moving means for moving while in contact with the conductor is provided, and the conductor can be uniformly contacted with the flexible pressure-sensitive body, so that it is possible to uniformly polarize the entire circumference. For this reason, there are no unpolarized portions, and stable characteristics without characteristic variations can be obtained. In addition, since the entire circumference of the flexible pressure sensitive body can be moved while being in contact with the conductor in a state where the contact resistance with the flexible pressure sensitive body is reduced, the productivity is improved. While improving, the damage of the flexible pressure sensitive body which arises by contact resistance can also be prevented.

  According to a second invention, in particular, in the first invention, the conductive foil is disposed so as to surround the entire circumference of the flexible pressure-sensitive body, so that the conductive foil is surrounded by the entire circumference of the flexible pressure-sensitive body. Can be uniformly and uniformly polarized from the entire periphery.

  In the third invention, in particular, in the first or second invention, by forming the conductor with a plurality of conductive foils, the portion not contacting the composite piezoelectric body and the conductor can be reduced, and the flexibility The piezoelectric body can be uniformly and evenly polarized.

  According to a fourth aspect of the present invention, in particular, in the first to third aspects of the present invention, the conductive member is fixed to a support member made of a conductive material, whereby the voltage applying means is connected to the single conductive member. Since a voltage can be applied to the conductor made of the foil, the connection from the voltage applying means can be simplified.

  According to a fifth aspect of the invention, in particular, in the first to fourth aspects of the invention, the flexible pressure sensitive member is rotated so as to rotate at least once while being in contact with the conductor during voltage application by the voltage applying means. Even if there is a place where the pressure body and the conductor do not contact, it is possible to uniformly contact the conductor by rotating the flexible pressure-sensitive body, so that uniform polarization can be performed. For this reason, there are no unpolarized portions, and stable characteristics without characteristic variations can be obtained.

According to a sixth invention, in particular, in the first to fifth inventions, when a plurality of conductors fixed to the support member are provided via a gap, a defective portion exists in the flexible pressure-sensitive body. A series of flexible pressure-sensitive bodies including a part of the electrode could not be polarized, but by intermittently providing a plurality of polarization electrodes, there was a part that could not be polarized with a certain length However, it becomes possible to polarize again by keeping the portion that could not be polarized to the minimum unit. Therefore, before forming the outer electrode of a series of flexible pressure-sensitive bodies, it can be detected that a minute defect exists within a certain length range, and when this is processed to produce a piezoelectric cable Yield can be improved.

According to a seventh aspect of the invention, in particular, in the second to sixth aspects of the invention, by fixing the conductor to a support member made of a conductive material, the voltage application means is connected to the support member, and the voltage is applied to each conductor. Therefore, connection from the voltage applying means can be simplified.
According to an eighth aspect of the present invention, a step is provided in which a flexible pressure-sensitive body is provided around the core electrode, and a conductor composed of a plurality of conductive foils that polarize the flexible pressure-sensitive body, and the core electrode is connected. It is a polarization method of a cable-shaped pressure sensor comprising a step of applying a voltage by a voltage applying means and a step of heating the flexible pressure sensitive body during polarization. And by this polarization method, voltage application is applied to the entire circumference of the cable, so that a cable-shaped pressure sensor having uniform polarization characteristics can be manufactured.

  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 perspective view showing a 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 pressure-sensitive body 12, a polymer material in which a piezoelectric base material such as lead zirconate titanate is combined with a polymer base material such as epoxy resin, urethane resin, chloroprene resin, chlorinated polyethylene, or silicon resin is used. . The flexible pressure sensitive body 12 is disposed so as to contact a conductor 13 made of a conductive foil. The conductor 13 made of conductive foil is made of iron, stainless steel, copper, brass, aluminum, or the like. Furthermore, a heating means 14 is provided on the top of the conductor 13 in order to heat the conductor 13. Polarization can be performed efficiently by polarizing the conductor 13 made of conductive foil while heating the flexible pressure-sensitive body 12. Further, a rotating drum was used as the moving means 15 for moving the flexible pressure sensitive body 12. The flexible pressure-sensitive body 12 is wound up by the moving means 15 and can be moved while being in contact with the conductor 13. By changing the rotation speed of the rotating drum that is the moving means 15, it is possible to easily adjust the time during which the flexible pressure sensitive body 12 contacts the conductor 13, in other words, the polarization time. In addition, since the moving means 15 can be automated, the yield can be improved.

  In the present embodiment, a 12 μm Al foil was used as the conductive foil. A cut is made in the central portion of the Al foil, and the cut portion is arranged so as to contact the entire circumference of the flexible pressure sensitive body.

  In this embodiment, as shown in FIG. 2, the conductor 13 has a concentric cut having a width of 0.2 mm and a length of 30 mm in the central portion of the conductive foil, and the flexible pressure sensitive body 12 is placed in the cut portion. The conductor 13 is configured so that the entire circumference of the flexible pressure-sensitive body 12 is in contact with the conductive foil. The output of the voltage application means 16 is connected to the conductor 13 to polarize the flexible pressure sensitive body 12.

By connecting in this way, a high voltage is applied between the core electrode 11 and the conductor 13 by the voltage applying means 16, so that the flexible pressure sensitive body 12 is polarized. In this embodiment, the applied voltage is 5 k.
Polarization was performed at V / mm. When the flexible pressure-sensitive body 12 includes a minute defect and the portion is disposed on the conductor 13, a high current is generated between the conductor 13 and the core electrode 11 due to a minute discharge generated in the defect portion. Although it cannot be polarized because it flows and is short-circuited, if the defective part is detached from the conductor 13 and there is no defect in the flexible pressure-sensitive body 12 disposed on the conductor 13, the conductor 13 and the core electrode 11 Since the insulation between them 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 13, but polarization is possible in other cases. Therefore, the flexible pressure-sensitive body 12 cannot be polarized as a whole due to the presence of defects. In the first embodiment, the core electrode 11 of the flexible pressure sensitive body 12 is set to the ground potential, and a DC voltage is applied between the core electrode 11 and the conductor 13. By connecting in this way, the direct current high voltage part dangerous to the human body can be limited to the conductor 13, and safety to the human body can be secured.

  In the conventional polarization device shown in FIG. 7, the vibration is applied to each of the portions that do not contact the block-shaped conductor 5 and the portions that contact the block-shaped conductor 5, and the voltage generated at that time is measured. There was a difference of about 1.6 times in output voltage between the part and the part in contact with the part. However, when the polarization device of the present invention was used and the vibration was applied in four directions with a 90 ° angle changed with respect to the coaxial direction of the flexible pressure sensitive body 12, the ratio of the highest output voltage to the smallest one was as follows. 1. It was suppressed to 20 times or less. Therefore, during the voltage application by the voltage application means 16, the voltage can be applied uniformly from the entire circumference of the flexible pressure sensitive body 12 by the conductor 13 in which the flexible pressure sensitive body 12 is composed of a plurality of conductive foils. Uniform polarization could be realized. In addition, since the contact with the flexible pressure-sensitive body 12 is reduced, it can be moved while being in contact with the flexible pressure-sensitive body 12 as compared with the case where the entire circumference of the flexible pressure-sensitive body 12 is in close contact with the conductor 13. In addition to improving productivity, it is also possible to prevent damage to the flexible pressure sensitive body caused by contact resistance. In particular, in the present embodiment, by using a foil as the conductor, it is possible to prevent the flexible pressure sensitive body 12 from being damaged even if it is in contact with the flexible pressure sensitive body 12.

  Further, the flexible pressure sensitive body 12 and the conductor 13 do not come into contact with each other by rotating the flexible pressure sensitive body 12 so as to make at least one rotation while being in contact with the conductor 13 during voltage application by the voltage applying means 16. The number of locations can be reduced, and uniform contact with the conductor can be performed evenly. As a result of applying vibration in four directions with a 90 ° angle change with respect to the coaxial direction of the flexible pressure-sensitive body 12, the ratio of the highest output voltage to the smallest output voltage could be suppressed to 1.14 times or less. .

(Embodiment 2)
FIG. 3 is an external perspective view of a polarization device for a cable-shaped pressure sensor according to Embodiment 2 of the present invention. 3 is different from the first embodiment in that the conductor 13 is composed of a plurality of strip-shaped conductive foils. Further, in this embodiment, the plurality of conductive foils are fixed by a support member 17 made of a conductive material. The support member 17 was composed of an aluminum block. With this configuration, the output of the voltage applying means 16 can be connected to one of the conductors 13 made of a plurality of conductive foils disposed on the support member 17, and the support member 17 can be connected to the output. This is the same as the state in which the output of the voltage applying means 16 is connected to all of the plurality of fixed conductors 13. Therefore, it is not necessary to connect the output of the voltage application means 16 to the plurality of conductors 13, and the configuration can be simplified. Similarly, the same effect can be obtained by connecting to the support member 18 instead of connecting the output of the voltage applying means 16 to one conductor 13.

(Embodiment 3)
FIG. 4 is an external perspective view of a polarization device for a cable-shaped pressure sensor according to Embodiment 3 of the present invention. 3 is different from the first embodiment in that a conductive foil constituting the conductor 13 is disposed so as to surround the entire circumference of the flexible pressure-sensitive body 12. In this embodiment,
The support member 17 has a ring shape, and a plurality of conductors 13 which are conductive foils are provided inside the ring.
The flexible pressure-sensitive body 12 passes through the ring and is polarized while contacting the conductor 13 which is a conductive foil on the entire circumference, so that it can be uniformly and evenly polarized from the entire circumference.

  In this embodiment, as a result of applying vibration in four directions with an angle changed by 90 ° with respect to the coaxial direction of the flexible pressure-sensitive body 12, the ratio of the highest output voltage to the smallest output voltage is suppressed to 1.10 times or less. It was. Therefore, the voltage can be uniformly applied from the entire circumference of the flexible pressure-sensitive body 12 by the conductor 13 in which the flexible pressure-sensitive body 12 is formed of a conductive foil while the voltage is applied by the voltage applying means 16. Can be realized.

(Embodiment 4)
FIG. 5 is an external perspective view of a polarization device for a cable-shaped pressure sensor according to Embodiment 3 of the present invention. In FIG. 5, the difference from the first embodiment is that a plurality of conductors 13 made of conductive foil fixed to the support member 18 are provided via gaps, and the flexible pressure-sensitive body 12 is continuously provided as a conductor. It is the point comprised so that 13 may be contacted. The same members as those in the first and second embodiments are given the same reference numerals.

  In the present embodiment, the output of the voltage applying means 16 is connected to the output of the voltage applying means 16 to each of the core electrode 11 and a plurality of supporting members 17, and the supporting members 17 are connected in parallel. By doing so, the output of the voltage applying means 16 is efficiently applied to the plurality of conductive foil conductors 13 fixed to the respective support members 18.

  For example, when the length of the support member 17 to which the conductor 13 is fixed is 2 m, the polarization time is shorter than a predetermined time or 2 m before and after the defective portion of the flexible pressure-sensitive body 12 (total 4 m). Not a defective part. However, when four conductors 13 fixed to the 0.5 m support member 18 are provided, 0.5 m before and after the defective portion (1 m in total) becomes a defective portion, and the defective portion can be reduced to ¼. Yield can be improved.

  Further, by providing a plurality of support members 17 and measuring the voltage or current value applied between the support member 17 and the core electrode 11, it is possible to detect which support member 17 has a defective portion. It is possible to contribute to the determination of a defective portion of the flexible pressure sensitive body 12.

  In addition, it is possible to adjust the polarization time by adjusting the length and the continuous number of the supporting members 17 together with the moving speed by the moving means 15, under conditions that match the purpose of use of the flexible piezoelectric body 12. It is also possible to configure so that the polarization conditions can be selected.

  As described above, the polarization device for a pressure sensor and the polarization method thereof according to the present invention prevent the entire flexible pressure sensing body from being polarized even if a defect exists, and a plurality of flexible pressure sensing bodies. By making the conductor made of conductive foil in contact with the entire circumference of the flexible pressure-sensitive body, it is possible to obtain uniform characteristics evenly polarized and stable characteristics without characteristic variation. It can be used for a polarization device such as a piezoelectric body.

FIG. 1 is an external perspective view showing a configuration of a polarization device in Embodiment 1 of the present invention. The perspective view which shows the structure of the electroconductive foil which is a conductor of the polarization apparatus in Embodiment 1 of this invention. 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 other 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. Outline drawing showing the structure of a conventional piezoelectric cable sensor External perspective view showing a configuration of a polarization device of a conventional piezoelectric cable sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Core electrode 12 Flexible pressure sensitive body 13 Electric conductor 14 Heating means 15 Moving means 16 DC voltage generating means 17 Support member 18 Heating element

Claims (8)

A flexible pressure-sensitive body provided around the core electrode; a conductor composed of a conductive foil provided so as to be in contact with the flexible pressure-sensitive body; and the core electrode and the conductor connected to each other. A pressure sensor polarization device, comprising: a voltage applying means; a heating means for heating the flexible pressure sensitive body; and a moving means for moving the flexible pressure sensitive body while contacting the conductor. 2. The pressure sensor polarization device according to claim 1, wherein a conductive foil is disposed so as to surround the entire circumference of the flexible pressure-sensitive body. 3. The pressure sensor polarization device according to claim 1, wherein the conductor is composed of a plurality of conductive foils. The pressure sensor polarization device according to any one of claims 1 to 3, wherein the conductor made of conductive foil is fixed to a support member made of a conductive material. The polarization of the pressure sensor according to any one of claims 1 to 4, wherein the flexible pressure sensitive member is rotated so as to rotate at least once while being in contact with the conductor during voltage application by the voltage applying means. apparatus. The conductive member fixed to the support member is provided in plural via a gap, and the flexible pressure-sensitive member is provided so as to be continuously in contact with the conductive member. The polarization device of the pressure sensor described. The polarization device for a cable-shaped pressure sensor according to any one of claims 2 to 6, wherein the voltage applying means is configured to be connected to the core electrode and the support member. A voltage is applied by a step of arranging a flexible pressure-sensitive body around the core electrode, a conductor composed of a conductive foil that polarizes the flexible pressure-sensitive body, and a voltage applying means connected to the core electrode. A pressure sensor polarization method comprising: a step; and heating the flexible pressure sensitive body during polarization.