JP3642288B2 - Coaxial flexible piezoelectric cable polarization apparatus and polarization method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to polarization of a coaxial flexible piezoelectric cable.
[0002]
[Prior art]
As shown in FIG. 4, the coaxial flexible piezoelectric cable has an outer electrode 4 formed on the outer surface of a piezoelectric tube 3 in which a coaxial flexible piezoelectric body 2 is formed around a core electrode 1, A protective coating layer 5 is formed around the periphery.
[0003]
Conventionally, flexible piezoelectric cables have been polarized as follows.
[0004]
In Reference 1 (“Piezoelectric Composite Material Composed of Piezoelectric Ceramic Powder and Synthetic Rubber”, Powder and Industry, Vol. 22, No. 1, pp. 50-56, 1990), a high voltage is applied between the core electrode 1 and the outer electrode 4. Is applied to polarize the coaxial flexible piezoelectric body 2. This is also specified in USP 4,568,851. Due to the 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 coaxial flexible piezoelectric body 2. In this respect, polarization plays an important role.
[0005]
[Problems to be solved by the invention]
However, the conventional method has the following problems. When a high voltage is applied between the core electrode 1 and the outer electrode 4, if a defect such as a minute crack or a gap exists in the coaxial flexible piezoelectric body 2, a minute discharge occurs at the defect portion. By this slight discharge, the constituent material of the flexible piezoelectric body 2 is thermally evaporated and scattered, and the core electrode 1 and the outer electrode 4 are short-circuited. As a result, since it becomes impossible to apply a high voltage between the core electrode 1 and the outer electrode 4, the coaxial flexible piezoelectric body 2 (usually a length of several hundreds m or more) cannot be polarized.
[0006]
Further, since the presence of defects cannot be detected until a high voltage is applied between the core electrode 1 and the outer electrode 4, in other words, except for polarization, it is impossible to detect the presence of defects until the coaxial flexible piezoelectric cable is completed. It becomes unstable and the yield decreases.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a piezoelectric tube in which a coaxial flexible piezoelectric body is formed around a core electrode, moving means for moving the piezoelectric tube , and stopping and moving the piezoelectric tube. Control means for controlling time or moving speed, and DC voltage generating means connected to the block-shaped conductor and the core electrode, and the piezoelectric tube is disposed on the surface of the block-shaped conductor. A polarization device for a coaxial flexible piezoelectric cable is provided.
[0008]
According to the above invention, since the coaxial flexible piezoelectric material is in contact with the block-shaped conductor, the block-shaped conductor acts as the outer electrode 4. Therefore, by applying a DC voltage between the block-shaped conductor and the core electrode by a DC voltage means, the portion of the coaxial flexible piezoelectric body disposed on the block-shaped conductor can be polarized.
[0009]
Further, the control means stops the movement time of the piezoelectric tubing, or can polarize the coaxial flexible piezoelectric member at the required time by controlling the moving speed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the polarization device according to the first aspect, the piezoelectric conductor is disposed on the surface of the block-like conductor so that the block-like conductor acts as an outer electrode. Therefore, by applying a high voltage between the block-shaped conductor and the core electrode, a coaxial flexible piezoelectric body (hereinafter referred to as a portion of the block-shaped conductor disposed on the surface of the block-shaped conductor and the surface of the block-shaped conductor). Only a polarized coaxial flexible piezoelectric body). Further, since it is not necessary to process the piezoelectric tube passage on the block-shaped conductor, the block-shaped conductor processing is facilitated. Further, since it is not necessary to dispose the piezoelectric tube in the groove or hole of the block-like conductor, the piezoelectric tube can be disposed more easily.
[0011]
In addition, the piezoelectric tube is provided with a control means for controlling the stop and moving time or moving speed of the piezoelectric tube, and polarization is performed by stopping or moving the piezoelectric tube. Thus, stopping the travel time of the piezoelectric tubing, or can polarize the coaxial flexible piezoelectric member at the required time by controlling the moving speed.
[0012]
When the coaxial flexible piezoelectric body in a portion including a minute defect becomes a polarized coaxial flexible piezoelectric body, the conduction means and the core electrode are caused by a short circuit between the core electrode and the outer electrode due to discharge at the defective portion. A high voltage cannot be applied between them. However, the polarized coaxial flexible piezoelectric body after the short-circuit portion is separated from the block-shaped conductor and the block-shaped conductor can be normally polarized again. Therefore, even if there is a defect portion, the entire coaxial flexible piezoelectric body does not become polarized. In addition, this indicates that a minute defect exists in a portion of the polarized coaxial flexible piezoelectric body having a certain length, so that the minute defect has a certain length range before forming the outer electrode. Can be detected.
[0013]
In addition to the structure of claim 1, the polarization device according to claim 2 heats the block-shaped conductor by a heating block provided with a heater, and the piezoelectric device disposed on the block-shaped conductor is heated. The heating means for applying heat is provided. Therefore, since the temperature of the piezoelectric tube can be controlled, the coaxial flexible piezoelectric body can be polarized at a necessary temperature.
[0014]
The polarization device according to claim 3 has a configuration in which a resistor is provided in series with the piezoelectric tube in addition to the configuration of the invention described above . When the coaxial flexible piezoelectric material in a portion including a minute defect becomes a polarized coaxial flexible piezoelectric material, the applied voltage is lowered in the coaxial flexible piezoelectric material and cannot be polarized. However, since the current can be controlled by an appropriate resistance, the DC voltage generating means is not damaged. In addition, the polarized coaxial flexible piezoelectric material after the defective portion of the coaxial flexible piezoelectric material is detached from the block-shaped conductor can be normally polarized again. Therefore, even if there is a defect portion, the entire coaxial flexible piezoelectric body does not become polarized. In addition, this indicates that a minute defect exists in a portion of the polarized coaxial flexible piezoelectric body having a certain length, so that the minute defect has a certain length range before forming the outer electrode. Can be detected.
[0015]
Invention according to claim 4, arranged piezoelectric tube on the surface of the block-shaped conductors, stopped before Symbol piezoelectric tube, or moved by moving means, stopping of the piezoelectric tube by the control means And a moving time or a moving speed, and a direct current voltage is applied between the core wire of the piezoelectric tube and the block-shaped conductor. Therefore, the block conductor acts as an outer electrode, and therefore, by applying a high voltage between the block conductor and the core electrode, the block conductor is disposed on the surface of the block conductor and in the passage of the block conductor. Only the coaxial flexible piezoelectric body in the part can be polarized. And since the control means which controls the stop and moving time or moving speed of a piezoelectric material tube is provided, a coaxial flexible piezoelectric material can be polarized in required time.
[0016]
Moreover, according to the method of the present invention, the piezoelectric tube can be continuously polarized.
[0017]
Polarization method according to claim 5, in the polarization method described above, and the core wire of the piezoelectric tube to a ground potential, a polarization method of applying a DC voltage between the core wire and the block-shaped conductors. When a DC high voltage is applied between the block-shaped conductor and the core electrode, a DC high-voltage portion that is dangerous to the human body can be limited to the block-shaped conductor, so that safety to the human body can be easily ensured by a partition wall or the like.
[0018]
In the polarization method according to claim 6 , the block conductor is heated by a heating block provided with a heater, and heat is applied to the piezoelectric tube disposed on the block conductor, This is a polarization method in which a DC voltage is applied between block-shaped conductors. Since the temperature of the piezoelectric tube can be controlled, the coaxial flexible piezoelectric material can be polarized at a necessary temperature.
[0019]
【Example】
Examples of the present invention will be described below with reference to FIGS.
[0020]
(Example 1)
FIG. 1 is an outline sketch showing the configuration of a coaxial flexible piezoelectric polarization device in a first embodiment of the present invention. A coaxial flexible piezoelectric body 2 is formed with respect to the core electrode 1 (hereinafter, this molded body is referred to as a piezoelectric tube 3). As the core electrode 1, a coiled metal wire, a wire bundled with fine metal wires, or the like is used. As the flexible piezoelectric body 2, a composite piezoelectric body in which a ceramic piezoelectric powder such as lead zirconate titanate is added to a polymer base material such as an epoxy resin, a urethane resin, a chloroprene resin, or a chlorinated polyethylene resin, PVDF, or the like is used. A polymer piezoelectric material is used.
[0021]
The piezoelectric tube 3 is disposed on the surface of the block-like conductor 6 and then moved by a moving means (not shown). As the block-like conductor 6, a conductor such as iron, stainless steel, copper, brass, or aluminum is used. The block-shaped conductor 6 is processed by cutting, grinding, extrusion, pressing, or the like. In this embodiment, aluminum that can be easily obtained and easily processed is used as the material of the block-shaped conductor 6. Specifically, for the piezoelectric tube 3 having an outer diameter of 2 mm, the width is 30 mm, the height is 20 mm, and the length is 500 mm. As a moving means (not shown), the piezoelectric tube 3 is wound around a winding drum, and the piezoelectric tube 3 is moved by rotating the winding drum. In FIG. 1, the moving direction of the piezoelectric tube 3 disposed on the block-like conductor 6 is indicated by an arrow.
[0022]
The temperature at which the coaxial flexible piezoelectric body 2 is polarized is generally higher than the temperature at which it is used. For this reason, a heating means is provided in order to appropriately maintain the temperature of the coaxial flexible piezoelectric body 2 during polarization. As a heating means, a heating block 71 provided with a heater 7 is used to heat the block-like conductor 6 to an arbitrary temperature via an insulating sheet 72. In this embodiment, mica having a thickness of 0.5 mm was used as the insulating sheet 72. However, polyimide, poly-tetra-fluoro-ethylene, polyethylene terephthalate (abbreviated as PET), silicone rubber, or the like may be used. Good. The piezoelectric tube 3 is indirectly heated from below the piezoelectric tube 3 by being disposed on the surface of the block-shaped conductor 6. Since the temperature of the piezoelectric tube 3 can be arbitrarily maintained by controlling the output of the heater 7, the coaxial flexible piezoelectric body 2 can be polarized at a necessary temperature.
[0023]
The block conductors 6 are electrically connected by lead wires 8b. The lead wire 8a is electrically connected to the positive electrode or the negative electrode of the DC voltage generating means 9, and the core electrode 1 is electrically connected to the other pole of the DC voltage generating means 9 via the lead wire 8a.
[0024]
Since a high voltage is applied between the core electrode 1 and the block-shaped conductor 6 by the DC voltage generating means 9 while the piezoelectric tube 3 is stationary or moved while being connected in this way, the coaxial flexible piezoelectric The body 2 is polarized. At the time of polarization, a high voltage of 5 to 10 kV / mm is applied to the core electrode 1 and the block-shaped conductor 6. Specifically, the piezoelectric tube 3 was polarized at a temperature of 120 ° C. and an applied voltage of 8 kV / mm 2.
[0025]
When a minute defect is included in the coaxial flexible piezoelectric member 2 and the portion is disposed on the block-like conductor 6, the block-like conductor 6 and the core are caused by a minute discharge generated at the defect portion. A short circuit occurs between the electrodes 1. As a result, polarization cannot be performed. However, if this defective portion is detached from the block-shaped conductor 6 and there is no defect in the coaxial flexible piezoelectric body 2 disposed in the block-shaped conductor 6 at that time, the block-shaped conductor 6 and the core are removed. Since the insulation between the electrodes 1 is restored again, polarization becomes possible. As described above, according to the polarization device of the present invention, polarization cannot be performed only when the portion including the defect is disposed on the surface of the block-like conductor 6, but in other cases, polarization is possible. Therefore, the piezoelectric tube 3 cannot be polarized throughout due to the presence of the defect. In addition, it is clear that a defect exists in the coaxial flexible piezoelectric body 2 at the time when the discharge occurs. Therefore, since it can be detected that a defect exists in the piezoelectric tube 3 having a certain length before the outer electrode 4 is formed, the defect portion can be easily removed after the piezoelectric cable is completed. As a result, the production can be stabilized and the yield can be improved.
[0026]
(Example 2)
FIG. 2 is an outline sketch showing the configuration of the coaxial flexible piezoelectric polarization device in the second embodiment of the present invention. The difference from the first embodiment is that a cover 10 is provided. The cover 10 is provided with a space so that the piezoelectric tube 3 can move, and has a concave shape. The piezoelectric tube 3 is indirectly heated from below the piezoelectric tube 3 by being disposed on the upper surface of the block-like conductor 6. Furthermore, since the piezoelectric tube 3 is covered with the cover 10, the temperature of the piezoelectric tube 3 can be kept more uniform, and the coaxial flexible piezoelectric body 2 can be polarized at a necessary temperature. As the cover 10, a general heat insulating material (glass wool, ceramic fiber, etc.), heat resistant resin, metal (iron, stainless steel, copper, brass, aluminum, etc.), etc. are used. In this embodiment, an aluminum extruded material was used as the cover 10.
[0027]
(Example 3)
FIG. 3 is an outline sketch showing the configuration of the coaxial flexible piezoelectric polarization device in the third embodiment of the present invention. In the present embodiment, in addition to the configuration of the first or second embodiment, the resistor 11 is provided in series with the piezoelectric tube 3. When the coaxial flexible piezoelectric member 2 in a portion including a minute defect becomes the polarized coaxial flexible piezoelectric member 2, the voltage applied to the coaxial flexible piezoelectric member 2 is lowered and cannot be polarized. However, since the current can be controlled by the resistor 11, the DC voltage generating means is not damaged, and the polarization of the coaxial flexible piezoelectric body 2 after the defect is removed from the block-shaped conductor is allowed. The flexible piezoelectric body 2 can be normally polarized again. Therefore, even if there is a defect portion, the entire coaxial flexible piezoelectric body 2 will not be polarized. In addition, this indicates that a minute defect exists in a portion of the polarized coaxial flexible piezoelectric body 2 having a certain length, so that the minute defect has a certain length before the outer electrode 4 is formed. It can be detected that it exists within the range.
[0028]
【The invention's effect】
According to the onset bright As described above, if it contains very small defects in the portion of the flexible piezoelectric member arranged in the block-shaped conductor, a certain length of the polarization flexible piezoelectric having defects The body cannot be polarized, but the remaining piezoelectric tubes can be polarized. In addition, before the outer electrode 4 is formed, it can be detected that a defect exists in the polarized flexible piezoelectric body having a certain length.
[0029]
Further, according to this onset Ming methods, can be continuously polarize the piezoelectric tube.
[Brief description of the drawings]
FIG. 1 is an outline sketch showing the configuration of a polarization device in Embodiment 1 of the present invention. FIG. 2 is an outline sketch showing the configuration of a polarization device in Embodiment 2 of the present invention. Fig. 4 is an external perspective view showing the configuration of a conventional coaxial flexible piezoelectric element.
DESCRIPTION OF SYMBOLS 1 Core electrode 2 Coaxial flexible piezoelectric body 3 Piezoelectric tube 4 Outer electrode 6 Conductor block 7 Heater 71 Heating block 10 Cover 11 Resistance

Claims (6)

A piezoelectric tube formed with coaxial flexible piezoelectric member surrounding the core electrode, moving means for moving the piezoelectric tube is stopped and the movement time of the piezoelectric tube or a control means for controlling the moving speed A coaxial flexible piezoelectric device having a DC voltage generating means connected to a block-shaped conductor and the core electrode , wherein the piezoelectric tube is disposed on a surface of the block-shaped conductor. Cable polarization device. 2. The coaxial flexible piezoelectric cable polarization device according to claim 1 , wherein a heating means for heating the block-like conductor is provided to heat the lower side of the piezoelectric tube . Claim is provided a resistance to the piezoelectric tube series 1 or coaxial flexible piezoelectric cable of the polarization device according to 2. A piezoelectric tube in which a coaxial flexible piezoelectric body is formed around the core electrode is stopped or moved on the surface of the block-shaped conductor, and the stop and moving time or moving speed of the piezoelectric tube is controlled by the control means. And a direct current voltage is applied between the block-like conductor and the core electrode. 5. The method for polarizing a coaxial flexible piezoelectric cable according to claim 4 , wherein the core wire of the piezoelectric tube is set to ground potential, and a DC voltage is applied between the core wire and the block-shaped conductor. 6. The method for polarizing a coaxial flexible piezoelectric cable according to claim 4, wherein a heating means for heating the block-shaped conductor is provided to heat the lower side of the piezoelectric tube .

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