JP6689119B2 - Piezoelectric element using braid form and device using them - Google Patents

Description

  The present invention relates to a braid-like piezoelectric element with a terminal in which a braid using a piezoelectric fiber is covered with a conductive layer, a cloth-like piezoelectric element using the braid-like piezoelectric element with a terminal, and a device using them.

  In recent years, so-called wearable sensors have been attracting attention, and eyeglass-shaped and wristwatch-shaped products have begun to appear. However, these devices have a feeling of being worn and are desired to be cloth-like, that is, clothing-like, which is the ultimate wearable. As such a sensor, a piezoelectric element using the piezoelectric effect of piezoelectric fibers is known. For example, Patent Document 1 discloses a piezoelectric element that includes two conductive fibers and one piezoelectric fiber, and has piezoelectric elements that are arranged on substantially the same plane while having contact points with each other. Has been done. Further, in Patent Document 2, a fibrous material or a molded material made of a piezoelectric polymer is used. In order to generate piezoelectricity by the tension applied in the axial direction of the fibrous material, the tension is applied in a direction different from the applied direction. A piezoelectric material characterized by being twisted is disclosed.

  On the other hand, in recent years, the number of input devices that employ a so-called touch panel system, that is, touch-type input devices, has significantly increased. In addition to bank ATMs and station ticket vending machines, smartphones, mobile phones, portable game consoles, portable music players, and the like, along with the development of thin display technology, the number of devices using a touch panel as an input interface has increased significantly. . As a means for realizing such a touch panel method, a method using a piezoelectric sheet or a piezoelectric fiber is known. For example, Patent Document 3 discloses a touch panel using a piezoelectric sheet made of L-type polylactic acid having a stretching axis oriented in a predetermined direction.

  In these wearable sensors and touch panel type sensors, it is desired to extract a large electric signal even for a small stress generated in the piezoelectric material due to a small deformation applied to the piezoelectric material. For example, it is desired to stably extract a large electric signal even with a relatively small stress generated in the piezoelectric material by bending and stretching a finger or rubbing the surface with a finger or the like.

  Although the piezoelectric fiber of Patent Document 1 is an excellent material that can be applied to various uses, it cannot be said that a large electric signal can be output for a stress generated by a relatively small deformation, and a large electric signal is obtained. It does not specify the technology. Further, in the piezoelectric element described in Patent Document 1, the conductive fiber that becomes the signal line is exposed, and therefore, in order to suppress the noise signal, it is necessary to construct a noise shield structure separately. Therefore, the piezoelectric element described in Patent Document 1 still has room for improvement in practical use.

  The piezoelectric fiber disclosed in Patent Document 2 can output an electric signal when the piezoelectric fiber is twisted in advance by twisting the piezoelectric fiber by a special manufacturing method. However, Patent Document 2 does not disclose a technique of generating a sufficient electric signal against bending stress such as bending or stretching of the piezoelectric fiber or shear stress caused by rubbing the surface of the piezoelectric fiber. Therefore, when such a piezoelectric fiber is used, it is difficult to extract a sufficient electric signal only by the stress generated by a relatively small deformation such as rubbing the surface.

  The piezoelectric sheet of Patent Document 3 can output an electric signal by deformation (stress) of the piezoelectric sheet. However, since it is a sheet in the first place, it is poor in flexibility and cannot be used flexibly like a cloth.

International Publication No. 2014/058077 Japanese Patent No. 3540208 JP, 2011-253517, A

  An object of the present invention is to provide a fibrous piezoelectric element capable of extracting a large electric signal and suppressing a noise signal even by a stress generated by a relatively small deformation. Another object of the present invention is to provide a piezoelectric element with a terminal that enables this element to be efficiently connected to a signal detection circuit.

As a combination of the conductive fiber and the piezoelectric fiber, the inventors of the present invention efficiently coat the surface of the conductive fiber serving as the core with the braided piezoelectric fiber and further provide a conductive layer around the piezoelectric element to improve the efficiency. We discovered that electricity can be extracted well and that noise signals can be suppressed.
In addition, various techniques for attaching a terminal to an insulation-coated conductor wire have been disclosed. However, when the terminal is connected to a conductive fiber that is covered with a piezoelectric fiber in a braided shape and a conductive layer is further provided around the braided wire, the conventional technique It was found that the above method is difficult to apply from the viewpoints of difficulty in removing the coating, characteristics of fibers of the sheath portion and noise of piezoelectricity. Furthermore, not only can the wiring from the ground terminal of the circuit to the surrounding conductive layer be prevented from interfering with noise at the terminal portion, but also the piezoelectric fiber can be unraveled as a result of complicated wiring work, and as a piezoelectric element, It turned out to be easy to lose functionality. Therefore, a specific structure should be adopted so that the electrical connection of the terminals connected to the core conductor and the surrounding conductive layer can be secured while fixing the fibers in the sheath of the connecting portion and the surrounding conductive layer at once. I found that can solve this problem.
Furthermore, when applied to wearable devices, by reducing the distance between the terminal of the piezoelectric element and the fixed part to the flexible substrate such as cloth, noise due to instability of the braided piezoelectric fiber is reduced. I figured out what I could do.
The present invention has been completed by inventing a method that can efficiently create a device having a plurality of braids and facilitates connection and disconnection with a circuit in order to make a wearable device with higher functionality.

That is, the present invention includes the following inventions.
1. A core formed of conductive fibers,
A sheath portion formed of a braided piezoelectric fiber so as to cover the core portion,
A conductive layer provided around the sheath,
A piezoelectric element including: a signal metal terminal connected and fixed to the core portion; and a shield metal terminal connected and fixed to the conductive layer, the signal metal terminal and the signal metal terminal A piezoelectric element in which a metal terminal for shielding is fixed to each other via an insulator.
2. 2. The piezoelectric element according to 1 above, wherein a coverage of the sheath with the conductive layer is 25% or more.
3. 3. The piezoelectric element according to 1 or 2, wherein the conductive layer is made of fiber.
4. 4. The piezoelectric element according to any one of 1 to 3 above, wherein the shield metal terminal covers and holds the signal metal terminal via an insulator.
5. The signal metal terminal is connected and fixed in one of the following modes A and B, and the piezoelectric element is fixed by the signal metal terminal or a component fixed to the signal metal terminal. Any one of the above 1 to 4, wherein at the end of the portion, the piezoelectric fibers that have been loosened from the sheath and separated from the core have a portion that is less than 20% of the entire piezoelectric fibers of the sheath. The piezoelectric element according to one item.
A) A part of the signal metal terminal grips a part having a length of 0.5 mm or more of a fiber constituting the end part of the piezoelectric element, and the grip part or a place within 1 mm from the grip part, A state in which the core portion of the piezoelectric element and the signal metal terminal are electrically connected and fixed directly or indirectly through a conductive material B) A part of the signal metal terminal is fork-shaped or needle-shaped The fork-shaped portion or the needle-shaped portion is connected to the conductive fiber of the core portion directly or indirectly through a conductive material while being in contact with the sheath portion of the piezoelectric element, and 10 mm from this connection point. 5. A mode in which the piezoelectric element is fixed to the signal metal terminal by another part of the signal metal terminal or a part fixed to the signal metal terminal in a place within In any one of 1 to 5 above, a part or all of the piezoelectric fiber of the sheath portion within 5 mm from a connection portion between the core portion and the signal metal terminal is fused and fused. The piezoelectric element described.
7. The surface of the sheath is provided with a conductive material made of solder or a conductive paste and electrically connected to the core, and the conductive material provided on the surface of the sheath and the signal metal. 7. The piezoelectric element according to any one of 1 to 6 above, wherein the core portion and the signal metal terminal are indirectly electrically connected by contact with the terminal.
8. A piezoelectric element comprising a cloth including the piezoelectric element according to any one of 1 to 7 above, wherein the signal metal terminal or the shield metal terminal has a length of 10 mm or less from a portion fixed to the piezoelectric element. In the range, at least a part of the piezoelectric element is fixed to a fabric-like substrate.
9. Two or more piezoelectric elements according to any one of the above 1 to 7 are arranged substantially in parallel, and two or more metal terminals for signals connected to the respective piezoelectric elements are collected in one connector housing. The piezoelectric element according to any one of 1 to 8 above, which is capable of being collectively connected to another connector.
10. 10. The piezoelectric element according to 9 above, wherein two or more of the piezoelectric elements according to any one of 1 to 7 above are arranged substantially parallel to each other as a part of a yarn constituting a woven fabric or a knitted fabric.
11. Piezoelectric fiber contains polylactic acid as the main component,
11. The piezoelectric element according to any one of 1 to 10 above, wherein a winding angle of the piezoelectric fiber with respect to the conductive fiber is 15 ° or more and 75 ° or less.
12. 12. The piezoelectric element according to any one of 1 to 11 above, wherein the total fineness of the piezoelectric fibers is 1 to 20 times the total fineness of the conductive fibers.
13. 13. The piezoelectric element according to any one of 1 to 12 above, wherein the fineness per piezoelectric fiber is not less than 1/20 times and not more than 2 times the total fineness of the conductive fibers.
14. 11. The piezoelectric element according to any one of 8 to 10 above, further comprising a conductive fiber that intersects and contacts at least a part of the piezoelectric element.
15. 15. The piezoelectric element according to the above 14, wherein the conductive fiber constitutes 30% or more of the fiber intersecting with the piezoelectric element.
16. The piezoelectric element according to any one of 1 to 15 above,
An amplifying unit that amplifies an electric signal output from the piezoelectric element according to the applied pressure,
Output means for outputting the electric signal amplified by the amplifying means,
Device with.

  According to the present invention, it is possible to provide a fibrous piezoelectric element with a terminal capable of extracting a large electric signal and suppressing a noise signal even by a stress generated by a relatively small deformation.

It is a schematic diagram which shows the structural example of the braided piezoelectric element which concerns on embodiment. It is a schematic diagram which shows the example of a connection of the braided piezoelectric element and metal terminal which concern on embodiment (mode A). It is a schematic diagram which shows the example of a connection of the braided piezoelectric element and metal terminal which concern on embodiment (mode B fork). It is a schematic diagram which shows the example of a connection of the braided piezoelectric element and metal terminal which concern on embodiment (mode B needle shape). It is a schematic diagram which shows the structural example of the cloth-like piezoelectric element which concerns on embodiment. It is a block diagram showing a device provided with a piezoelectric element concerning an embodiment. It is a schematic diagram which shows the structural example of the device provided with the cloth-like piezoelectric element which concerns on embodiment. It is a schematic diagram which shows the other structural example of the device provided with the cloth-like piezoelectric element which concerns on embodiment.

(Braid-shaped piezoelectric element)
FIG. 1 is a schematic diagram showing a configuration example of a braided piezoelectric element according to an embodiment.
The braided piezoelectric element 1 covers the core portion 3 formed of the conductive fiber B, the sheath portion 2 formed of the braided piezoelectric fiber A so as to cover the core portion 3, and the sheath portion 2. And a conductive layer 4.
The coverage of the sheath 2 with the conductive layer 4 is preferably 25% or more. Here, the coverage is the ratio of the area of the conductive region contained in the conductive layer 4 when the conductive layer 4 is projected onto the sheath 2 and the surface area of the sheath 2, and the value is preferably 25% or more, It is more preferably 50% or more, further preferably 75% or more. If the coverage of the conductive layer 4 is less than 25%, the effect of suppressing noise signals may not be sufficiently exhibited. When the conductive region is not exposed on the surface of the conductive layer 4, for example, when the sheath 2 is covered by using a fiber containing the conductive region as the conductive layer 4, the sheath 2 of the fiber is moved to the sheath 2. The ratio of the projected area to the surface area of the sheath 2 can be used as the coverage.

  The conductive region is a part that is responsible for conductivity contained in the conductive layer 4, and refers to, for example, a conductive fiber part when the conductive layer 4 is composed of conductive fibers and insulating fibers.

  In the braided piezoelectric element 1, a large number of piezoelectric fibers A densely surround the outer peripheral surface of at least one conductive fiber B. Although not bound to a particular theory, when the braid-shaped piezoelectric element 1 is deformed, stress is generated in each of the many piezoelectric fibers A, which causes an electric field in each of the many piezoelectric fibers A. (Piezoelectric effect), and as a result, it is presumed that a voltage change in which the electric fields of a large number of piezoelectric fibers A surrounding the conductive fiber B are superimposed occurs in the conductive fiber B. That is, the electric signal from the conductive fiber B is increased as compared with the case where the braided sheath 2 of the piezoelectric fiber A is not used. As a result, in the braid-shaped piezoelectric element 1, a large electric signal can be taken out even by the stress generated by a relatively small deformation. The conductive fibers B may be plural.

  Here, the piezoelectric fiber A preferably contains polylactic acid as a main component. “As a main component” means that polylactic acid is the most abundant component of the components of the piezoelectric fiber A. The lactic acid unit in the polylactic acid is preferably 90 mol% or more, more preferably 95 mol% or more, still more preferably 98 mol% or more.

The winding angle α of the piezoelectric fiber A with respect to the conductive fiber B is preferably 15 ° or more and 75 ° or less. That is, the winding angle α of the piezoelectric fiber A with respect to the direction of the central axis CL of the conductive fiber B (core portion 3) is preferably 15 ° or more and 75 ° or less. However, in the present embodiment, since the central axis CL of the conductive fiber B overlaps with the central axis of the braid (sheath portion 2) of the piezoelectric fiber A (hereinafter, also referred to as “braid axis”), the piezoelectric fiber. It can be said that the winding angle α of the piezoelectric fiber A with respect to the direction of the braid axis of A is preferably 15 ° or more and 75 ° or less. From the viewpoint of extracting a larger electric signal, the angle α is more preferably 25 ° or more and 65 ° or less, further preferably 35 ° or more and 55 ° or less, and 40 ° or more and 50 ° or less. Is particularly preferred. This is because if the angle α is out of this angle range, the electric field generated in the piezoelectric fiber A is significantly reduced, and the electric signal obtained by the conductive fiber B is significantly reduced.
The angle α can also be referred to as an angle formed by the main direction of the piezoelectric fiber A forming the sheath 2 and the central axis CL of the conductive fiber B, and a part of the piezoelectric fiber A is loosened. It may be fluffy.

  Here, the reason why the electric field generated in the piezoelectric fiber A is significantly reduced is as follows. The piezoelectric fiber A contains polylactic acid as a main component and is uniaxially oriented in the fiber axis direction of the piezoelectric fiber A. Here, polylactic acid generates an electric field when shear stress is generated in the orientation direction (in this case, the direction of the fiber axis of the piezoelectric fiber A), but tensile stress or compression is applied in the orientation direction. When a stress is generated, an electric field is not generated so much. Therefore, in order to cause shear stress in the piezoelectric fiber A when it is deformed parallel to the direction of the braid axis, the orientation direction of the piezoelectric fiber A (polylactic acid) is set in a predetermined angle range with respect to the braid axis. It is presumed that it is good to be in.

  In the braid-shaped piezoelectric element 1, as long as the object of the present invention is achieved, the sheath portion 2 may be combined with a fiber other than the piezoelectric fiber A to carry out the fiber mixing, and the core portion 3 may be electrically conductive. You may perform a mixed fiber etc. by combining with fibers other than the fiber B.

  There is no particular limitation on the length of the braid-shaped piezoelectric element including the core portion 3 of the conductive fiber B, the sheath portion 2 of the braid-shaped piezoelectric fiber A, and the conductive layer 4 covering the sheath portion 2. For example, the braided piezoelectric element may be manufactured continuously in manufacturing, and then cut to a required length and used. The length of the braided piezoelectric element is 1 mm to 10 m, preferably 5 mm to 2 m, more preferably 1 cm to 1 m. If the length is too short, the convenience of the fiber shape will be lost, and if the length is too long, it will be necessary to consider the resistance value of the conductive fiber B.

Hereinafter, each configuration will be described in detail.
(Conductive fiber)
The conductive fiber B may be any one as long as it exhibits conductivity, and any known fiber can be used. Examples of the conductive fibers B include metal fibers, fibers made of a conductive polymer, carbon fibers, fibers made of a polymer in which a fibrous or granular conductive filler is dispersed, or a conductive material on the surface of a fibrous material. A fiber provided with a layer having Examples of the method for providing the conductive layer on the surface of the fibrous material include metal coating, conductive polymer coating, and winding of conductive fibers. Among them, the metal coat is preferable from the viewpoint of conductivity, durability, flexibility and the like. Specific methods for coating the metal include vapor deposition, sputtering, electrolytic plating, and electroless plating, but plating is preferable from the viewpoint of productivity. Fibers plated with such a metal can be referred to as metal-plated fibers.

  As the base fiber coated with a metal, known fibers can be used with or without conductivity, for example, polyester fiber, nylon fiber, acrylic fiber, polyethylene fiber, polypropylene fiber, vinyl chloride fiber, aramid fiber, In addition to synthetic fibers such as polysulfone fibers, polyether fibers, and polyurethane fibers, natural fibers such as cotton, hemp, and silk, semi-synthetic fibers such as acetate, and regenerated fibers such as rayon and cupra can be used. The base fiber is not limited to these, and known fibers can be arbitrarily used, and these fibers may be used in combination.

  Any metal may be used as the metal coated on the base fiber, as long as it exhibits conductivity and exhibits the effects of the present invention. For example, gold, silver, platinum, copper, nickel, tin, zinc, palladium, indium tin oxide, copper sulfide, etc., or a mixture or alloy thereof can be used.

  When the metal fiber-coated organic fiber having bending resistance is used as the conductive fiber B, the conductive fiber is hardly broken, and the durability and safety as a sensor using a piezoelectric element are excellent.

  The conductive fiber B may be a multifilament in which a plurality of filaments are bundled, or may be a monofilament composed of one filament, or a single spun yarn or a yarn bundle in which a plurality of spun yarns are bundled. It may be in a form (including twisted yarn), or may be a long / short composite yarn in which a filament and a spun yarn are combined. The multifilament is preferable from the viewpoint of long-term stability of electric characteristics. In the case of a monofilament or one spun yarn, the single yarn diameter is 1 μm to 5000 μm, preferably 2 μm to 100 μm. More preferably, it is 3 μm to 50 μm. In the case of a multifilament, a yarn bundle form, and a long / short composite yarn, the number of filaments or yarns is preferably 1 to 100,000, more preferably 5 to 500, and further preferably 10 to 100. However, the fineness and the number of the conductive fibers B are the fineness and the number of the core portion 3 used when producing the braid, and a multifilament formed by a plurality of monofilaments is also a bundle of a plurality of spun yarns. Both the yarn bundle form (including twisted yarn) and the long and short composite yarn in which the filament and the spun yarn are combined are counted as one conductive fiber B. Here, the core 3 is the total amount including the fibers even when fibers other than the conductive fibers are used.

  When the diameter of the fiber is small, the strength is lowered and the handling becomes difficult, and when the diameter is large, the flexibility is sacrificed. The cross-sectional shape of the conductive fiber B is preferably a circle or an ellipse from the viewpoint of designing and manufacturing the piezoelectric element, but is not limited to this.

Further, in order to efficiently take out the electric output from the piezoelectric polymer, the electric resistance is preferably low, the volume resistivity is preferably 10 ⁻¹ Ω · cm or less, and more preferably 10 ⁻² Ω · cm or less, more preferably 10 ⁻³ Ω · cm or less. However, the resistivity of the conductive fiber B is not limited to this as long as sufficient strength can be obtained by detecting the electric signal.

The conductive fiber B must be resistant to repeated bending and twisting movements for the purposes of this invention. As the index, one having a higher knot strength is preferred. The knot strength can be measured by the method of JIS L1013: 2010 8.6. The degree of knot strength suitable for the present invention is preferably 0.5 cN / dtex or more, more preferably 1.0 cN / dtex or more, and further preferably 1.5 cN / dtex or more. , 2.0 cN / dtex or more is most preferable. Further, as another index, one having a smaller bending rigidity is preferred. The bending rigidity is generally measured by a measuring device such as KES-FB2 pure bending tester manufactured by Kato Tech Co., Ltd. The degree of bending rigidity suitable for the present invention is preferably smaller than that of carbon fiber "Tenax" (registered trademark) HTS40-3K manufactured by Toho Tenax Co., Ltd. Specifically, the flexural rigidity of the conductive fiber is preferably 0.05 × 10 ⁻⁴ N · m ² / m or less, and 0.02 × 10 ⁻⁴ N · m ² / m or less. It is more preferably 0.01 × 10 ⁻⁴ N · m ² / m or less.

(Piezoelectric fiber)
As the piezoelectric polymer that is the material of the piezoelectric fiber A, a polymer having piezoelectricity such as polyvinylidene fluoride or polylactic acid can be used, but in the present embodiment, the piezoelectric fiber A is the main component as described above. It is preferable to include polylactic acid. Polylactic acid is excellent in productivity because, for example, it is easily oriented by stretching after melt spinning and exhibits piezoelectricity, and the electric field orientation treatment required for polyvinylidene fluoride or the like is unnecessary. However, this is not intended to preclude the use of polyvinylidene fluoride or other piezoelectric materials in the practice of the present invention.

  As polylactic acid, depending on its crystal structure, L-lactic acid, poly-L-lactic acid obtained by polymerizing L-lactide, D-lactic acid, poly-D-lactic acid obtained by polymerizing D-lactide, and further, those There is a stereocomplex polylactic acid having a hybrid structure and the like, but any one having piezoelectricity can be used. From the viewpoint of high piezoelectric constant, poly-L-lactic acid and poly-D-lactic acid are preferable. Since poly-L-lactic acid and poly-D-lactic acid have opposite polarizations under the same stress, it is possible to use them in combination depending on the purpose.

  The optical purity of polylactic acid is preferably 99% or more, more preferably 99.3% or more, and further preferably 99.5% or more. If the optical purity is less than 99%, the piezoelectric coefficient may be significantly reduced, and it may be difficult to obtain a sufficient electric signal due to the shape change of the piezoelectric fiber A. In particular, the piezoelectric fiber A preferably contains poly-L-lactic acid or poly-D-lactic acid as the main component, and the optical purity of these is preferably 99% or more.

  The piezoelectric fiber A containing polylactic acid as a main component is stretched at the time of manufacturing and is uniaxially oriented in the fiber axis direction. Further, the piezoelectric fiber A is preferably not only uniaxially oriented in the fiber axis direction but also containing polylactic acid crystals, and more preferably uniaxially oriented polylactic acid crystals. This is because polylactic acid exhibits higher piezoelectricity due to its high crystallinity and uniaxial orientation.

The crystallinity and the uniaxial orientation are determined by the homo-PLA crystallinity X _homo (%) and the crystal orientation Ao (%). As the piezoelectric fiber A of the present invention, it is preferable that the _homo PLA crystallinity X _homo (%) and the crystal orientation Ao (%) satisfy the following formula (1).
X _homo × Ao × Ao ÷ 10 ⁶ ≧ 0.26 (1)
If the above formula (1) is not satisfied, the crystallinity and / or the uniaxial orientation may be insufficient, and the output value of the electric signal with respect to the operation may decrease, or the sensitivity of the signal with respect to the operation in the specific direction may decrease. is there. The value on the left side of the above formula (1) is more preferably 0.28 or more, further preferably 0.3 or more. Here, each value is obtained according to the following.

Homopolylactic acid crystallinity X _homo :
The homopolylactic acid crystallinity X _homo is determined by crystal structure analysis by wide-angle X-ray diffraction analysis (WAXD). In wide-angle X-ray diffraction analysis (WAXD), an X-ray diffraction pattern of a sample is recorded on an imaging plate under the following conditions by a transmission method using an ultrax18 type X-ray diffractometer manufactured by Rigaku.
X-ray source: Cu-Kα ray (confocal mirror)
Output: 45kV x 60mA
Slit: 1st: 1mmΦ, 2nd: 0.8mmΦ
Camera length: 120mm
Cumulative time: 10 minutes Sample: Align 35 mg of polylactic acid fiber to form a fiber bundle of 3 cm.
In the obtained X-ray diffraction pattern, the _total scattering intensity I _total was obtained over the azimuth angle, and the integral of each diffraction peak derived from the homopolylactic acid crystal that appears near 2θ = 16.5 °, 18.5 °, 24.3 ° was obtained. The sum ΣI _HMi of intensities is _obtained . From these values, the homopolylactic acid crystallinity X _homo is calculated according to the following formula (2).
Homopolylactic acid crystallinity X _homo (%) = ΣI _HMi / I _total × 100 (2)
It should be _noted that ΣI _HMi is calculated by subtracting the diffuse scattering due to the background and amorphous in the total scattering intensity.

(2) Crystal orientation degree Ao:
Regarding the crystal orientation degree Ao, in the X-ray diffraction pattern obtained by the above-mentioned wide-angle X-ray diffraction analysis (WAXD), the direction of the diffraction peak derived from the homopolylactic acid crystal appearing in the vicinity of 2θ = 16.5 ° in the radial direction, The intensity distribution with respect to the angle (°) is taken, and it is calculated from the total half width Σ _Wi (°) of the obtained distribution profile by the following formula (3).
Crystal orientation degree Ao (%) = (360−ΣW _i ) ÷ 360 × 100 (3)

  Since polylactic acid is a polyester that is relatively rapidly hydrolyzed, in the case where the heat and humidity resistance is a problem, a known hydrolysis inhibitor such as an isocyanate compound, an oxazoline compound, an epoxy compound, or a carbodiimide compound is added. Good. Further, if necessary, an antioxidant such as a phosphoric acid compound, a plasticizer, a photodegradation inhibitor, etc. may be added to improve the physical properties.

  Although polylactic acid may be used as an alloy with other polymers, if polylactic acid is used as the main piezoelectric polymer, it contains at least 50% by mass or more of polylactic acid based on the total mass of the alloy. It is preferably 70% by mass or more, and most preferably 90% by mass or more.

  Examples of the polymer other than polylactic acid in the case of alloy include polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate copolymer, polymethacrylate and the like, but are not limited thereto, and the present invention is not limited thereto. Any polymer may be used as long as it exhibits the desired piezoelectricity.

  The piezoelectric fiber A may be a multifilament in which a plurality of filaments are bundled, or may be a monofilament composed of one filament, or a single spun yarn or a yarn bundle in which a plurality of spun yarns are bundled. It may be in a form (including twisted yarn), and may be a long / short composite yarn in which a filament and a spun yarn are combined. In the case of a monofilament or one spun yarn, the single yarn diameter is 1 μm to 5 mm, preferably 5 μm to 2 mm, more preferably 10 μm to 1 mm. In the case of multifilament, yarn bundle form, and long / short composite yarn, the single yarn diameter is 0.1 μm to 5 mm, preferably 2 μm to 100 μm, and more preferably 3 μm to 50 μm. The number or filaments of multifilaments, yarn bundles, and long / short composite yarns is preferably 1 to 100,000, more preferably 50 to 50,000, and further preferably 100 to 20,000. However, the fineness and the number of the piezoelectric fibers A are the fineness and the number per one carrier when producing the braid, and the multifilament formed of a plurality of monofilaments is also a bundle of a plurality of spun yarns. Both the yarn bundle form (including twisted yarn) and the long and short composite yarn in which the filament and the spun yarn are combined are counted as one piezoelectric fiber A. Here, even when a fiber other than the piezoelectric fiber is used in one carrier, the total amount including it is included.

  In order to use such a piezoelectric polymer as the piezoelectric fiber A, any known method for forming a fiber from a polymer can be adopted as long as the effects of the present invention are exhibited. For example, a method of extruding a piezoelectric polymer to form a fiber, a method of melt-spinning a piezoelectric polymer to form a fiber, a method of forming a piezoelectric polymer into a fiber by dry or wet spinning, a piezoelectric polymer A method of forming fibers by electrostatic spinning, a method of forming a film and then cutting it into thin pieces, and the like can be adopted. For these spinning conditions, a known method may be applied depending on the piezoelectric polymer to be used, and a melt spinning method that is industrially easy to produce may be usually adopted. Furthermore, after forming the fibers, the formed fibers are stretched. As a result, the piezoelectric fiber A which is uniaxially stretched and has a large piezoelectric property including crystals is formed.

  Further, the piezoelectric fiber A can be subjected to treatments such as dyeing, twisting, plying, and heat treatment before using the braids prepared as described above.

  Furthermore, the piezoelectric fibers A may rub against each other when forming a braid, and may break or fluff. Therefore, it is preferable that the strength and abrasion resistance are high. It is preferably 5 cN / dtex or more, more preferably 2.0 cN / dtex or more, further preferably 2.5 cN / dtex or more, and most preferably 3.0 cN / dtex or more. The wear resistance can be evaluated by the JIS L1095 9.10.2 B method or the like, and the number of times of friction is preferably 100 times or more, more preferably 1000 times or more, further preferably 5000 times or more. Most preferably, it is 10,000 times or more. The method for improving the wear resistance is not particularly limited, and any known method can be used, for example, improving the crystallinity, adding fine particles, or surface-treating. You can In addition, when the braid is processed, a lubricant can be applied to the fibers to reduce friction.

Further, it is preferable that the contraction rate of the piezoelectric fiber has a small difference from the contraction rate of the conductive fiber described above. If the difference in shrinkage is large, the braid may be bent or the flatness of the fabric may become poor, or the piezoelectric signal may become weak, when heat is applied during the post-treatment process after making the braid or after making the fabric, or when it is actually used, or due to aging. It may happen. When the shrinkage rate is quantified by the boiling water shrinkage rate described later, it is preferable that the boiling water shrinkage rate S (p) of the piezoelectric fiber and the boiling water shrinkage rate S (c) of the conductive fiber satisfy the following formula (4). .
| S (p) -S (c) | ≦ 10 (4)
The left side of the above formula (4) is more preferably 5 or less, further preferably 3 or less.

In addition, it is preferable that the contraction rate of the piezoelectric fiber has a small difference from the contraction rate of fibers other than the conductive fiber, for example, the insulating fiber. If the difference in shrinkage is large, the braid may be bent or the flatness of the fabric may become poor, or the piezoelectric signal may become weak, when heat is applied during the post-treatment process after making the braid or after making the fabric, or when it is actually used, or due to aging. It may happen. When the shrinkage rate is quantified by the boiling water shrinkage rate, it is preferable that the boiling water shrinkage rate S (p) of the piezoelectric fiber and the boiling water shrinkage rate S (i) of the insulating fiber satisfy the following formula (5).
| S (p) -S (i) | ≦ 10 (5)
The left side of the above formula (5) is more preferably 5 or less, and further preferably 3 or less.

Further, it is preferable that the shrinkage rate of the piezoelectric fiber is small. For example, when the shrinkage rate is quantified by boiling water shrinkage rate, the shrinkage rate of the piezoelectric fiber is preferably 15% or less, more preferably 10% or less, further preferably 5% or less, and most preferably 3% or less. is there. As a means for reducing the shrinkage rate, any known method can be applied. For example, the heat treatment can reduce the shrinkage rate by relaxing the orientation of the amorphous part and increasing the crystallinity. The timing is not particularly limited, and examples thereof include drawing, twisting, braiding, and cloth forming. The boiling water shrinkage ratio is measured by the following method. A cassette having a winding number of 20 was made with a measuring machine having a frame circumference of 1.125 m, a load of 0.022 cN / dtex was applied, and the cassette was hung on a scale plate to measure the initial cassette length L0. Then, the casks were treated in a boiling water bath at 100 ° C. for 30 minutes, allowed to cool, and again hung on the scale plate by applying the above load, and the casks length L after contraction was measured. Using the measured L0 and L, the boiling water shrinkage rate is calculated by the following formula (6).
Shrinkage rate of boiling water = (L0-L) / L0 × 100 (%) (6)

(Coating)
The surface of the conductive fiber B, that is, the core portion 3 is covered with the piezoelectric fiber A, that is, the braided sheath portion 2. The thickness of the sheath 2 covering the conductive fibers B is preferably 1 μm to 10 mm, more preferably 5 μm to 5 mm, further preferably 10 μm to 3 mm, most preferably 20 μm to 1 mm. preferable. If it is too thin, there may be a problem in strength, and if it is too thick, the braided piezoelectric element 1 may become hard and difficult to deform. In addition, the sheath portion 2 referred to here means a layer adjacent to the core portion 3.

In the braided piezoelectric element 1, the total fineness of the piezoelectric fibers A of the sheath portion 2 is preferably 1/2 times or more and 20 times or less the total fineness of the conductive fibers B of the core portion 3, and preferably 1 times or more. 15 times or less, more preferably 2 times or more and 10 times or less. When the total fineness of the piezoelectric fiber A is too small as compared with the total fineness of the conductive fiber B, the amount of the piezoelectric fiber A surrounding the conductive fiber B is too small and the conductive fiber B cannot output a sufficient electric signal. Furthermore, the conductive fiber B may come into contact with another conductive fiber in the vicinity. If the total fineness of the piezoelectric fibers A is too large with respect to the total fineness of the conductive fibers B, the amount of the piezoelectric fibers A surrounding the conductive fibers B is too large and the braided piezoelectric element 1 becomes hard and difficult to be deformed. That is, in any case, the braided piezoelectric element 1 does not function sufficiently as a sensor.
The total fineness referred to here is the sum of the finenesses of all the piezoelectric fibers A constituting the sheath portion 2, and for example, in the case of a general 8-braided cord, it is the total fineness of 8 fibers.

  Further, in the braided piezoelectric element 1, the fineness per piezoelectric fiber A of the sheath portion 2 is preferably 1/20 times or more and 2 times or less of the total fineness of the conductive fibers B, and It is more preferably 15 times or more and 1.5 times or less, and further preferably 1/10 times or more and 1 time or less. If the fineness per piezoelectric fiber A is too small relative to the total fineness of the conductive fibers B, the piezoelectric fibers A are too small and the conductive fibers B cannot output a sufficient electric signal. A may be cut. If the fineness per piezoelectric fiber A is too large with respect to the total fineness of the conductive fibers B, the piezoelectric fibers A become too thick and the braided piezoelectric element 1 becomes hard and difficult to deform. That is, in any case, the braided piezoelectric element 1 does not function sufficiently as a sensor.

  In addition, when a metal fiber is used as the conductive fiber B or when the metal fiber is mixed with the conductive fiber A or the piezoelectric fiber B, the fineness ratio is not limited to the above. This is because, in the present invention, the above ratio is important from the viewpoint of contact area and coverage, that is, area and volume. For example, when the specific gravity of each fiber exceeds 2, the ratio of the average cross-sectional area of the fibers is preferably the ratio of the fineness.

  It is preferable that the piezoelectric fiber A and the conductive fiber B are in close contact with each other as much as possible, but an anchor layer or an adhesive layer is provided between the conductive fiber B and the piezoelectric fiber A in order to improve the adhesion. May be.

  As a coating method, a method is used in which the conductive fiber B is used as a core yarn and the piezoelectric fiber A is wound around it in a braided shape. On the other hand, the shape of the braid of the piezoelectric fiber A is not particularly limited as long as it can output an electric signal in response to the stress generated by the applied load, but it is not limited to the 8-braid or 16-braid having the core portion 3. A braid is preferred.

  The shapes of the conductive fiber B and the piezoelectric fiber A are not particularly limited, but it is preferable that they are as concentric as possible. When the multifilament is used as the conductive fiber B, the piezoelectric fiber A may be coated so that at least a part of the surface (fiber peripheral surface) of the multifilament of the conductive fiber B is in contact. The piezoelectric fibers A may or may not be coated on the surface (fiber peripheral surface) of all filaments constituting the multifilament. The coating state of the piezoelectric fiber A on each filament inside the multifilament of the conductive fiber B may be appropriately set in consideration of the performance as the piezoelectric element, the handling property, and the like.

  Since the braid-like piezoelectric element 1 of the present invention does not need to have an electrode on its surface, it is not necessary to further cover the braid-like piezoelectric element 1 itself, and there is an advantage that malfunction does not occur easily.

(Conductive layer)
As the mode of the conductive layer 4, in addition to coating, winding of a film, cloth, or fiber is conceivable, or they may be combined.

  The coating for forming the conductive layer 4 may be any material containing a substance having conductivity, and any known material may be used. For example, a metal, a conductive polymer, or a polymer in which a conductive filler is dispersed may be used.

  When the conductive layer 4 is formed by winding a film, a film obtained by forming a conductive polymer or a polymer in which a conductive filler is dispersed is used, and a conductive layer is provided on the surface. A film may be used.

  When the conductive layer 4 is formed by winding a cloth, a cloth having conductive fibers 6 described later as a constituent component is used.

  When the conductive layer 4 is formed by winding the fibers, a covering method, a braid, and a braid can be considered as the method. The fiber used is the conductive fiber 6, and the conductive fiber 6 may be the same kind as the above-mentioned conductive fiber B or a different kind of conductive fiber. As the conductive fiber 6, for example, a metal fiber, a fiber made of a conductive polymer, a carbon fiber, a fiber made of a polymer in which a fibrous or granular conductive filler is dispersed, or a conductive material on the surface of a fibrous material is used. A fiber provided with a layer having Examples of the method for providing the conductive layer on the surface of the fibrous material include metal coating, conductive polymer coating, and winding of conductive fibers. Among them, the metal coat is preferable from the viewpoint of conductivity, durability, flexibility and the like. Specific methods for coating the metal include vapor deposition, sputtering, electrolytic plating, electroless plating and the like, but plating is preferable from the viewpoint of productivity. Fibers plated with such a metal can be referred to as metal-plated fibers.

  As the base fiber coated with a metal, known fibers can be used with or without conductivity, for example, polyester fiber, nylon fiber, acrylic fiber, polyethylene fiber, polypropylene fiber, vinyl chloride fiber, aramid fiber, In addition to synthetic fibers such as polysulfone fibers, polyether fibers, and polyurethane fibers, natural fibers such as cotton, hemp, and silk, semi-synthetic fibers such as acetate, and regenerated fibers such as rayon and cupra can be used. The base fiber is not limited to these, and known fibers can be arbitrarily used, and these fibers may be used in combination.

  Any metal may be used as the metal coated on the base fiber, as long as it exhibits conductivity and exhibits the effects of the present invention. For example, gold, silver, platinum, copper, nickel, tin, zinc, palladium, indium tin oxide, copper sulfide, etc., or a mixture or alloy thereof can be used.

  When the metal fiber-coated organic fiber having bending resistance is used as the conductive fiber 6, the conductive fiber is very unlikely to be broken, and is excellent in durability and safety as a sensor using a piezoelectric element.

  The conductive fiber 6 may be a multifilament in which a plurality of filaments are bundled, or may be a monofilament composed of one filament, or a single spun yarn or a yarn bundle in which a plurality of spun yarns are bundled. It may be in a form (including twisted yarn), or may be a long / short composite yarn in which a filament and a spun yarn are combined. The multifilament is preferable from the viewpoint of long-term stability of electric characteristics. In the case of a monofilament or one spun yarn, the single yarn diameter is 1 μm to 5000 μm, preferably 2 μm to 100 μm. More preferably, it is 3 μm to 50 μm. In the case of a multifilament, a yarn bundle form, and a long / short composite yarn, the number of filaments or yarns is preferably 1 to 100,000, more preferably 5 to 500, and further preferably 10 to 100.

  When the diameter of the fiber is small, the strength is lowered and the handling becomes difficult, and when the diameter is large, the flexibility is sacrificed. The cross-sectional shape of the conductive fiber 6 is preferably a circle or an ellipse from the viewpoint of designing and manufacturing the piezoelectric element, but is not limited to this.

Further, in order to enhance the effect of suppressing the noise signal, the electric resistance is preferably low, and the volume resistivity is preferably 10 ⁻¹ Ω · cm or less, more preferably 10 ⁻² Ω · cm or less, further preferably Is 10 ⁻³ Ω · cm or less. However, the resistivity is not limited to this as long as the effect of suppressing the noise signal can be obtained.

The conductive fibers 6 must be resistant to repeated bending and twisting movements for the purposes of this invention. As the index, one having a higher knot strength is preferred. The knot strength can be measured by the method of JIS L1013 8.6. The degree of knot strength suitable for the present invention is preferably 0.5 cN / dtex or more, more preferably 1.0 cN / dtex or more, and further preferably 1.5 cN / dtex or more. , 2.0 cN / dtex or more is most preferable. Further, as another index, one having a smaller bending rigidity is preferred. The bending rigidity is generally measured by a measuring device such as KES-FB2 pure bending tester manufactured by Kato Tech Co., Ltd. The degree of bending rigidity suitable for the present invention is preferably smaller than that of carbon fiber "Tenax" (registered trademark) HTS40-3K manufactured by Toho Tenax Co., Ltd. Specifically, the bending rigidity of the conductive fiber is preferably 0.05 × 10 ⁻⁴ N · m ² / m or less, and 0.02 × 10 ⁻⁴ N · m ² / m or less. It is more preferably 0.01 × 10 ⁻⁴ N · m ² / m or less.

(Terminal)
The braided piezoelectric element 1 of the present invention further includes a signal metal terminal connected and fixed to the core portion thereof, and a shield metal terminal connected and fixed to the conductive layer 4 provided around the sheath portion. , The metal terminal for signal and the metal terminal for shield are fixed to each other via an insulator, and these two metal terminals can be handled as an integrated connector component, so that connection to a signal processing circuit is simple. Also, it can be performed reliably and noise can be reduced stably.
In addition, it is preferable that the shielding metal terminal covers and holds the signal metal terminal via an insulator from the viewpoint of reducing noise that enters at the terminal portion. Covered here means that the metal terminal for shielding is arranged close to the metal terminal for signal, and in that state, it is projected on the front view, rear view, left side view, right side view, plan view and bottom view. At this time, the ratio of the area where the regions of the shielding metal terminals overlap with each other in the total area of the regions of the signal metal terminals in each drawing is 50% or more. In addition, an opening or an insulator necessary for connecting another terminal to the signal metal terminal may be provided.

The signal metal terminal of the braided piezoelectric element 1 of the present invention is preferably connected and fixed to the core of the signal metal terminal in any one of the following modes A and B.
A) A part of the signal metal terminal grips a part of the fiber constituting the end part of the braided piezoelectric element with a length of 0.5 mm or more, and at the grip part or a place within 1 mm from the grip part, A mode in which the core of the braided piezoelectric element and the signal metal terminal are connected and fixed directly or indirectly through a conductive material.
B) A part of the signal metal terminal is fork-shaped or needle-shaped, and the fork-shaped portion or needle-shaped portion is in contact with the sheath portion of the braid-shaped piezoelectric element and is directly or electrically conductive with the conductive fiber of the core portion. The braided piezoelectric element is indirectly connected through a material, and within a location within 10 mm from this connection point, the braided piezoelectric element is connected to another portion of the signal metal terminal or a component fixed to the signal metal terminal. The state of being fixed to the made terminal.

(Connection according to mode A)
FIG. 2 (Mode A) is a schematic diagram showing a configuration example of the connection mode of A according to the embodiment.
The piezoelectric fiber and the conductive fiber forming the end of the braided piezoelectric element are held by the holding portion which is a part of the signal metal terminal. The gripped state refers to a state in which the braided piezoelectric elements are sandwiched or rolled up by the gripped portions of the signal metal terminals and fixed to each other. A structure in which the claw-shaped signal metal terminal is plastically deformed by a tool to be in the gripped state, and a state in which the signal terminal is engaged by the metal terminal or the engaging portion provided in the insulating portion. The following structure is preferably adopted. The signal metal terminal has a shape that can be connected to another terminal on the right side of FIG. The signal metal terminal is fixed to the shield metal terminal via an insulator, and the shield metal terminal is arranged so as to cover the signal metal terminal. The metal terminal for shielding has a grip portion, and the conductive layer 4 is gripped by the grip portion to be electrically connected and fixed to the conductive layer 4.
As a connector component capable of such a connection, the coaxial connector disclosed in JP-A-4-2828080, JP-A-2002-324636, JP-A-2012-79652 or the like can be preferably used.

  The length of the gripped portion of the signal metal terminal is preferably 0.5 mm or more. If the length is shorter than this, the braid-shaped piezoelectric element and the signal metal terminal are not firmly fixed to each other, and various forces are required for wearable device applications. When the element is added to the element, the braid-like piezoelectric element may be separated from the signal metal terminal, or the electrical connection may become unstable. The length of the grip portion is more preferably 0.7 mm or more, and further preferably 1.0 mm or more. Here, the length of the gripping portion is the length at which the metal braid-like piezoelectric element is gripping the braid-like piezoelectric element, and is the length measured in the length direction of the braid-like piezoelectric element. When the braided piezoelectric element is gripped at a plurality of places as shown in FIG. 2, it is the total length of the gripped portions.

  At the gripped portion of the signal metal terminal or within 1 mm from the gripped portion, the core portion of the braided piezoelectric element and the signal metal terminal are directly or indirectly connected via a conductive material. Although not specifically shown in FIG. 2, in the present invention, as described later, it is preferable that the sheath portion of the braid-shaped piezoelectric element is not unraveled at the fixed portion with the signal metal terminal, and therefore the signal metal terminal is gripped. The coating of the sheath is not completely removed even in the part, but by partially removing it by melting the sheath and applying a conductive material such as solder or conductive paste, the core of the braided piezoelectric element and the signal It allows metal terminals to be electrically connected. However, even if the sheath is unraveled by cutting the end of the braid-like piezoelectric element or removing the sheath, the insulator that fixes the signal metal terminal sufficiently grasps the sheath, and This does not apply when it can be considered that the sheath is not unraveled, that is, when it does not become a harmful noise source.

(Connection according to mode B)
FIG. 3 (Mode B fork shape) is a schematic diagram showing a configuration example of a connection mode by a signal metal terminal including the fork-shaped portion of the mode B according to the embodiment. FIG. 4 (Mode B needle-shaped) is a schematic diagram showing a configuration example of a connection mode by the signal metal terminal including the needle-shaped portion of the mode B according to the embodiment.
In FIGS. 3 and 4, as shown in the respective cross-sectional views, the fork-shaped portion or the needle-shaped portion, which is a part of the signal metal terminal, comes into contact with the sheath portion of the braid-shaped piezoelectric element while the core portion is electrically conductive. The conductive fibers are directly or indirectly connected through a conductive material. The signal metal terminal has a shape that can be connected to another terminal on the right side of each drawing. The signal metal terminal is fixed to the shield metal terminal via an insulator, and the shield metal terminal is arranged so as to cover the signal metal terminal. The metal terminal for shielding has a grip portion, and the conductive layer 4 is gripped by the grip portion to be electrically connected and fixed to the conductive layer 4.
A stack type cable connector disclosed in Japanese Patent Laid-Open No. 2006-277960 can be preferably used as a connector component capable of such a connection.

  In mode B, when the fixing force of the braid-shaped piezoelectric element by only the fork-shaped portion or the needle-shaped portion of the signal metal terminal is insufficient, another portion of the signal metal terminal or the signal metal terminal It is preferable that the braid-like piezoelectric element is fixed to the signal metal terminal also by the component fixed to the terminal. Further, such an additional fixing part is preferably located within 10 mm from the connection part between the signal metal terminal and the conductive fiber of the core part. If there is an additional fixing part only over 10 mm from the connection point, the whole unfixed braided piezoelectric element and the sheath part unraveled by the metal terminal for signals move unstably due to impact on the sensor and noise. Can cause In order to fix the braid-shaped piezoelectric element by another part of the signal metal terminal or a component fixed to the signal metal terminal, the braid-shaped piezoelectric element may be attached to a part of the signal metal terminal as in the mode A. Although it can be gripped, the braided piezoelectric element is sandwiched and gripped by parts such as a resin housing fixed to the signal metal terminal, or it is fixed to the signal metal terminal or the signal metal terminal with an adhesive. It is more preferable to fix it to the other parts.

  In FIGS. 3 and 4, as an example of the additional fixing portion, an insulator is provided as an exterior of the signal metal terminal, and the braid-like piezoelectric element is sandwiched and gripped by the left side portion of the insulator in the drawings, It is used as a fixed part by a part fixed to the signal metal terminal. As shown in the sectional views of FIGS. 3 and 4, the insulator is divided into an upper portion and a lower portion, and the upper portion of the insulator may be fixed to the signal metal terminal in advance. When connecting and fixing the braided piezoelectric element to the signal metal terminal, sandwich the braided piezoelectric element between the signal metal terminal fixed to the upper part of the insulator and the lower part of the insulator, and apply force from the top and bottom. It is preferable that the signal metal terminal is inserted into the braided piezoelectric element and the upper and lower insulators are fixed in contact with each other. Therefore, the fork-shaped portion or the needle-shaped portion of the signal metal terminal has the thinness or thinness necessary for being inserted between the fibers of the piezoelectric fiber of the sheath portion, or the piezoelectric fiber of the sheath portion. It is preferable to have the sharpness necessary for partially cutting the. One signal metal terminal may have a plurality of fork-shaped portions or a plurality of needle-shaped portions, or may have both a fork-shaped portion and a needle-shaped portion at the same time. When using a signal metal terminal having a fork-shaped portion, if the thickness of the sheath portion is too thick or the total fineness of the core portion is too low, it is difficult for the fork-shaped portion to contact the core portion. It is preferably 1 mm or less, more preferably 0.5 mm or less, and the total fineness of the core is preferably 50 dTex or more, more preferably 100 dTex or more.

(Terminal connection part)
The braided piezoelectric element of the present invention is such that at the end of the portion fixed by the signal metal terminal or the component fixed to the signal metal terminal, the piezoelectric fiber separated from the core part by unraveling the tissue of the sheath part It is preferable to have a portion of the sheath portion which is less than 20% of the whole piezoelectric fiber. If it exceeds 20%, the piezoelectric fibers distant from the core part move instable due to an impact on the sensor or the like to randomly generate piezoelectric signals, which causes noise. The part where the braided piezoelectric element is fixed by the signal metal terminal or the part fixed to the signal metal terminal means the part gripped by the signal metal terminal in the mode A or the signal metal in the mode B. The braided piezoelectric element is formed by a portion in which the fork-shaped portion and the needle-shaped portion of the manufactured terminal are in contact with the sheath portion of the braided piezoelectric element and a component such as a resin housing fixed to the signal metal terminal in the modes A and B. Is a portion where the braided piezoelectric element is fixed to a signal metal terminal or a component fixed to the signal metal terminal by an adhesive. The end refers to a region within 1 mm from the boundary between the fixed portion and the non-fixed portion. When the tissue of the sheath part is unraveled and separated from the core part, the piezoelectric fiber of the sheath part reaches the place where the distance from the surface of the core part is 1.5 times or more the average thickness of the sheath part of the braided piezoelectric element. It refers to the state in which the piezoelectric fibers are present (that is, the fibers are supplied from one carrier when the braid is created). When the piezoelectric fiber of the sheath portion is a multi-filament, 50% or more of the filaments constituting one piezoelectric fiber is at least 1.5 times the average thickness of the sheath portion of the braided piezoelectric element from the surface of the core portion. If it reaches the core, it is determined that the one piezoelectric fiber has loosened the tissue of the sheath portion and is separated from the core portion. The determination may be made by observing from the side surface of the braided piezoelectric element or by observing the cross section. When observing the cross section, fix it with an epoxy resin or the like before cutting so that the sheath does not unravel excessively during cutting.

  The signal metal terminal of the element of the present invention may be fixed to the end of the braided piezoelectric element as shown in FIG. 2 (Mode A), FIG. 3 (Mode B fork) and FIG. 4 (Mode B needle). It is also possible to fix it in the middle of the braided piezoelectric element.

  In order to achieve the object of suppressing noise derived from piezoelectricity, the element of the present invention fixes the signal metal terminal without removing the fiber of the sheath part of the braid which is an insulating coating, and the core part and the signal metal. It has a seemingly contradictory structure of ensuring electrical connection of the manufactured terminals. The following two examples will be given as structures for achieving this.

  As one example of the structure, a structure in which part or all of the piezoelectric fibers of the connecting portion between the core portion and the signal metal terminal and the sheath portion within 5 mm from the connecting portion lose their fiber shape and are fused is preferably adopted. . That is, by melting the piezoelectric fiber forming the sheath after fixing the signal metal terminal, the piezoelectric fiber in the sheath that prevents the electrical connection between the signal metal terminal and the core is caused to flow, and the signal metal is After ensuring electrical connection between the manufactured terminal and the core, the piezoelectric fiber can be solidified and fixed again by cooling or the like. A solid obtained by melting and solidifying the piezoelectric fiber has an advantage that the braid-like piezoelectric element and the signal metal terminal can be fixed like an adhesive. Furthermore, when a polymer fiber such as polylactic acid is used as the piezoelectric fiber, the solid that is solidified after melting loses piezoelectricity, and thus there is no possibility of becoming a noise source. When polylactic acid fiber is used, the piezoelectric fiber can be melted by a heat treatment at a temperature of 160 ° C. or higher, but unnecessary decomposition of polylactic acid and unnecessary melting of the sheath and deformation of other members are prevented. Therefore, it is preferable to carry out at 220 ° C. or lower. It is also possible to melt the piezoelectric fiber when fixing the signal metal terminal, and it is preferable to increase the grip pressure of the signal metal terminal while confirming that the electrical connection is secured, which is unnecessary. In order to prevent the sheath portion from being deformed, it is preferable to heat the signal metal terminal so that heat is transferred to the sheath portion and melted. From the viewpoint of process safety and simultaneous processing of a plurality of devices, it is also preferable to carry out after mounting the signal metal terminals.

  As another example of the structure, the sheath surface is provided with a conductive material made of solder or conductive paste and electrically connected to the core portion, and the conductive material provided on the sheath surface and the signal metal are used. An example is a structure in which the core portion and the signal metal terminal are indirectly connected by contact with the terminal. The conductive material has a function of being electrically connected by being interposed between the core portion and the signal metal terminal, and is changed from a liquid state (including a slurry state) to a solid state by a temperature change, solvent removal or a chemical reaction. Any material that changes can be used, and a conductive paste containing a conductive filler such as solder, metal or carbon is preferably used. In particular, solder and silver paste are preferably used in terms of handleability and conductivity. In the braided piezoelectric element of the present invention, the insulating coating is an assembly of fibers, so that the conductive material is impregnated into the inside by adhering the above-mentioned conductive material from the surface, and the conductive surface electrically connected to the core portion is the sheath surface. However, in order to ensure more electrical connection with the core, it is possible to adjust the fluidity of the conductive material before solidification to a low level so that it easily penetrates into the core or before solidification of the conductive material. It is preferable to apply a physical stimulus to the braided piezoelectric element to widen the gap between the fibers of the sheath portion, or to attach a conductive material to the cut surface at the end of the braided piezoelectric element.

(Fixing to base material)
In the braided piezoelectric element of the present invention, at least a part of the braided piezoelectric element is a cloth within a length of 10 mm from the portion where the signal metal terminal or the shield metal terminal is fixed to the braided piezoelectric element. It is preferably fixed to the base material. If there is no place fixed to the cloth-like substrate within 10 mm, the braid-like piezoelectric element that is not fixed moves unstablely due to an impact on the cloth-like substrate and the metal terminals, which causes noise. The fixation to the cloth-like base material may be performed by post-processing such as adhesion and sewing, or may be fixed by weaving or knitting as threads constituting the cloth structure.

(Production method)
In the braid-shaped piezoelectric element 1 of the present invention, the surface of at least one conductive fiber B is covered with the braid-shaped piezoelectric fiber A, and the manufacturing method thereof includes, for example, the following method. That is, it is a method in which the conductive fiber B and the piezoelectric fiber A are manufactured in separate steps, and the piezoelectric fiber A is wound around the conductive fiber B in a braided shape and covered. In this case, it is preferable that the coating be as concentric as possible.

  In this case, the melt spinning temperature is preferably 150 ° C. to 250 ° C., and the stretching temperature is preferably 40 ° C. to 150 ° C. as the preferable spinning and stretching conditions when polylactic acid is used as the piezoelectric polymer forming the piezoelectric fiber A. The draw ratio is preferably 1.1 times to 5.0 times, and the crystallization temperature is preferably 80 ° C to 170 ° C.

  As the piezoelectric fiber A wound around the conductive fiber B, a multifilament in which a plurality of filaments are bundled may be used, a monofilament may be used, or one spun yarn or a plurality of spun yarns. It may be in the form of a bundle of yarns (including twisted yarns), or may be a long / short composite yarn in which a filament and a spun yarn are combined. As the conductive fiber B around which the piezoelectric fiber A can be wound, a multifilament in which a plurality of filaments are bundled may be used, or a monofilament may be used. Furthermore, one spun yarn, a yarn bundle form in which a plurality of spun yarns are bundled (including a twisted yarn) may be used, and a long-short composite yarn in which a filament and a spun yarn are combined may be used.

  As a preferable form of the coating, the conductive fiber B is used as the core yarn, and the piezoelectric fiber A is braided around the core yarn to form a round braid (Tubular Braid). . More specifically, an 8-placing braid or a 16-placing braid having the core portion 3 may be mentioned. However, for example, the piezoelectric fiber A may be formed into a shape like a braided tube, and the conductive fiber B may be inserted into the braided tube as a core to cover the piezoelectric fiber A.

  The conductive layer 4 is manufactured by coating or winding a fiber, and the winding of a fiber is preferable from the viewpoint of ease of manufacturing. Covering, knitting, and braiding are conceivable as the method for winding the fibers, and any method may be used.

  By the manufacturing method as described above, it is possible to obtain the braid-shaped piezoelectric element 1 in which the surface of the conductive fiber B is covered with the braid-shaped piezoelectric fiber A and the conductive layer 4 is further provided around it.

  The braided piezoelectric element 1 of the present invention does not require the formation of an electrode for detecting an electric signal on the surface, and thus can be manufactured relatively easily.

(Protective layer)
A protective layer may be provided on the outermost surface of the braided piezoelectric element 1 of the present invention. The protective layer is preferably insulative, and more preferably made of a polymer from the viewpoint of flexibility and the like. When the protective layer is made to have insulating properties, of course, in this case, the protective layer is deformed or rubbed on the protective layer, but these external forces reach the piezoelectric fiber A, There is no particular limitation as long as it can induce polarization. The protective layer is not limited to that formed by coating with a polymer or the like, and may be a film, a cloth, a fiber, or the like, or a combination thereof.

  When the thickness of the protective layer is as thin as possible, shear stress is easily transmitted to the piezoelectric fiber A, but when it is too thin, problems such as destruction of the protective layer itself are likely to occur, and therefore, preferably 10 nm to 200 μm, The thickness is more preferably 50 nm to 50 μm, further preferably 70 nm to 30 μm, and most preferably 100 nm to 10 μm. The shape of the piezoelectric element can also be formed by this protective layer.

  Further, it is possible to provide a plurality of layers made of piezoelectric fibers or a plurality of layers made of conductive fibers for extracting a signal. Of course, the order and the number of layers of the protective layer, the layer made of the piezoelectric fiber, and the layer made of the conductive fiber are appropriately determined according to the purpose. In addition, as a winding method, a method of forming a braided structure on the outer layer of the sheath 2 or covering it may be mentioned.

(Action)
The braid-like piezoelectric element 1 of the present invention has a stress generated when a load is applied to the braid-like piezoelectric element 1, for example, by rubbing the surface of the braid-like piezoelectric element 1, that is, the stress applied to the braid-like piezoelectric element 1. It can be used as a sensor for detecting its size and / or applied position. Further, in the braided piezoelectric element 1 of the present invention, if shear stress is applied to the piezoelectric fiber A by pressing force other than rubbing or bending deformation, it is of course possible to take out an electric signal. For example, the "stress applied to the braided piezoelectric element 1" is the frictional force between the surface of the piezoelectric element, that is, the surface of the piezoelectric fiber A and the surface of the contacted object such as a finger, or the piezoelectric fiber. The resistance force in the vertical direction with respect to the surface or the tip portion of A, the resistance force with respect to the bending deformation of the piezoelectric fiber A, and the like are included. In particular, the braided piezoelectric element 1 of the present invention can efficiently output a large electric signal when bent or rubbed in a direction parallel to the conductive fiber B.

  Here, the "stress applied to the braided piezoelectric element 1" is, for example, about 1 to 1000 Pa as a standard when the stress is such that the surface is rubbed with a finger. Needless to say, it is possible to detect the magnitude of the applied stress and the applied position even if the stress is higher than the above. When inputting with a finger or the like, it is preferable to operate even with a load of 1 Pa or more and 500 Pa or less, more preferably 1 Pa or more and 100 Pa or less. Of course, it operates as described above even when the load exceeds 500 Pa.

  Further, by measuring the capacitance change between the conductive fiber B of the core portion of the braided piezoelectric element 1 and the conductive layer 4, it is possible to detect the deformation due to the pressure applied to the braided piezoelectric element 1. become. Furthermore, when a plurality of braid-shaped piezoelectric elements 1 are used in combination, the pressure applied to the braid-shaped piezoelectric elements 1 is measured by measuring the capacitance change between the conductive layers 4 of each braid-shaped piezoelectric element 1. It is also possible to detect the deformation due to.

(Cloth-like piezoelectric element)
FIG. 5 is a schematic view showing a configuration example of a cloth-like piezoelectric element using the braid-like piezoelectric element according to the embodiment.
The cloth-shaped piezoelectric element 7 includes a cloth 8 including at least one braid-shaped piezoelectric element 1. The fabric 8 is not limited as long as at least one of the fibers (including the braid) forming the fabric is the braid-shaped piezoelectric element 1, and the braid-shaped piezoelectric element 1 can exhibit the function as the piezoelectric element. It may be any woven or knitted fabric. In forming a cloth, as long as the object of the present invention is achieved, it may be combined with other fibers (including braid) and subjected to interwoven or interwoven. Of course, the braided piezoelectric element 1 may be used as a part of the fibers (for example, warp or weft) forming the cloth, or the braided piezoelectric element 1 may be embroidered or bonded to the cloth. Good. In the example shown in FIG. 5, the cloth-like piezoelectric element 7 has at least one braid-like piezoelectric element 1 and insulating fibers 9 as warps, and conductive fibers 10 and insulating fibers 9 as wefts alternately. It is a plain plain fabric. The conductive fibers 10 may be the same kind as the conductive fibers B or different kinds of conductive fibers, and the insulating fibers 9 will be described later. All or part of the insulating fibers 9 and / or the conductive fibers 10 may be in a braid form.

  In this case, when the cloth-shaped piezoelectric element 7 is deformed by being bent or the like, the braid-shaped piezoelectric element 1 is also deformed along with the deformation, and thus the cloth-shaped piezoelectric element 7 is generated by the electric signal output from the braid-shaped piezoelectric element 1. The deformation of can be detected. Since the cloth-shaped piezoelectric element 7 can be used as a cloth (woven or knitted material), it can be applied to, for example, a clothing-shaped wearable sensor.

  In the cloth-shaped piezoelectric element 7 shown in FIG. 5, the conductive fiber 10 intersects the braid-shaped piezoelectric element 1 and is in contact therewith. Therefore, the conductive fiber 10 crosses and contacts at least a part of the braided piezoelectric element 1 and covers it, and shields at least a part of electromagnetic waves from the outside toward the braided piezoelectric element 1. Can be seen. Such a conductive fiber 10 has a function of reducing the influence of electromagnetic waves on the braided piezoelectric element 1 by being grounded. That is, the conductive fiber 10 can function as an electromagnetic wave shield of the braided piezoelectric element 1. Thereby, for example, the S / N ratio (signal-to-noise ratio) of the cloth-shaped piezoelectric element 7 can be remarkably improved without superposing the conductive cloth for electromagnetic wave shielding on and under the cloth-shaped piezoelectric element 7. In this case, the higher the ratio of the conductive fibers 10 in the weft (in the case of FIG. 5) that intersects with the braid-shaped piezoelectric element 1 from the viewpoint of electromagnetic wave shielding, the better. Specifically, 30% or more of the fibers forming the fabric 8 and intersecting with the braided piezoelectric element 1 are preferably the conductive fibers 10, more preferably 40% or more, and 50% or more. Is more preferable. As described above, by inserting the conductive fibers 10 as at least a part of the fibers forming the cloth in the cloth-like piezoelectric element 7, the cloth-like piezoelectric element 7 having an electromagnetic wave shielding function can be obtained.

  Examples of the woven structure of the woven fabric include a plain fabric, a twill weave, a satin weave, and the like, a modified fabric, a warp double woven fabric, a weft double woven fabric, and the like, a warp velvet, and the like. The knitted fabric may be a circular knitted fabric (weft knitted fabric) or a warp knitted fabric. Preferred examples of the structure of the circular knit (weft knit) include flat knitting, rubber knitting, double-sided knitting, pearl knitting, tuck knitting, floating knitting, single-sided knitting, lace knitting, and bristle knitting. Examples of the warp knitting structure include single denby knitting, single atlas knitting, double cord knitting, half tricot knitting, fleece knitting, and jacquard knitting. The number of layers may be a single layer or a multilayer of two or more layers. Further, it may be a napped woven fabric or a napped knitted fabric composed of a napped part composed of a cut pile and / or a loop pile and a ground structure part.

(Multiple piezoelectric elements)
Further, in the cloth-shaped piezoelectric element 7, it is possible to use a plurality of braid-shaped piezoelectric elements 1 side by side. As a method of arranging, for example, the braid-shaped piezoelectric elements 1 may be used for all warps or wefts, or the braid-shaped piezoelectric elements 1 may be used for every several or a part thereof. Alternatively, the braid-shaped piezoelectric element 1 may be used as a warp in a certain portion, and the braid-shaped piezoelectric element 1 may be used as a weft in another portion.

  In addition, when a plurality of braid-like piezoelectric elements 1 are arranged side by side, the distance between the conductive fibers B is short, which is efficient in taking out an electric signal. Particularly, in the present invention, a plurality of metal terminals connected to each braided piezoelectric element are collectively fixed to one connector housing to form a connector having a plurality of poles, and a connector having a plurality of other poles collectively. By making connection possible, device manufacturing efficiency can be increased and connection and disconnection by the user can be facilitated, which is particularly preferable. As described above, by incorporating it into the structure of the woven or knitted fabric, it is possible to easily arrange a plurality of braid-like piezoelectric elements substantially in parallel at desired intervals, and it is easy to fix each metal terminal to the connector. There are advantages. Here, “substantially parallel” means that two fibers that are adjacent to each other, such as two adjacent warp yarns that form a plain weave and two adjacent courses that form a plain knitted fabric, are not parallel because they are bent locally. It refers to the state where they are parallel when a straight line is drawn to average them. At this time, by adjusting the weaving density and the knitting density, it is preferable to adjust the intervals of the plurality of braid-like piezoelectric elements to the terminal intervals of the connector often used in electronic circuits. 0.5 mm, 1.0 mm, 1.25 mm, 1 It is more preferable to adjust the distance to any one of 0.5 mm, 2.0 mm, and 2.54 mm (distance between the centers of the braids). Also, using a connector having a fork-shaped portion of mode B, in which a plurality of metal terminals are fixed in advance in one connector housing, and connecting a plurality of metal terminals to a plurality of braid-like piezoelectric elements at once. Is particularly preferable from the viewpoint of simplifying the process.

(Insulating fiber)
In the cloth-shaped piezoelectric element 7, an insulating fiber can be used for a portion other than the braid-shaped piezoelectric element 1 (and the conductive fiber 10). At this time, as the insulating fiber, a fiber having a stretchable material and shape can be used for the purpose of improving the flexibility of the cloth piezoelectric element 7.

  By arranging the insulating fiber in this manner in addition to the braid-shaped piezoelectric element 1 (and the conductive fiber 10), the operability of the cloth-shaped piezoelectric element 7 (example: easiness of movement as a wearable sensor) is improved. It is possible to

As such an insulating fiber, a volume resistivity of 10 ⁶ Ω · cm or more can be used, more preferably 10 ⁸ Ω · cm or more, and further preferably 10 ¹⁰ Ω · cm or more.

Examples of insulating fibers include polyester fibers, nylon fibers, acrylic fibers, polyethylene fibers, polypropylene fibers, vinyl chloride fibers, aramid fibers, polysulfone fibers, polyether fibers, polyurethane fibers, and other synthetic fibers, as well as cotton, hemp, silk, and the like. Natural fibers, semi-synthetic fibers such as acetate, and regenerated fibers such as rayon and cupra can be used. It is not limited to these, and known insulating fibers can be arbitrarily used. Further, these insulating fibers may be used in combination, or may be combined with a fiber having no insulating property to form a fiber having an insulating property as a whole.
Further, fibers having any known cross-sectional shape can also be used.

(Piezoelectric element application technology)
In any of the piezoelectric elements such as the braided piezoelectric element 1 and the cloth piezoelectric element 7 of the present invention, contact with the surface, pressure, and shape change can be output as an electric signal. It can be used as a sensor (device) for detecting the magnitude of stress applied to an element and / or the position applied. Further, this electric signal can be used as a power generation element by using it as a power source for driving other devices or by storing electricity. Specifically, power generation by using it for moving parts of things that move spontaneously such as humans, animals, robots, machines, power generation on the surface of shoe soles, rugs, structures that receive pressure from the outside, shape change in fluid Power generation, etc. In addition, since an electric signal is generated due to a change in shape in the fluid, it is possible to adsorb or suppress adhesion of the charged substance in the fluid.

  FIG. 6 is a block diagram showing a device 11 including the piezoelectric element 12 of the present invention. The device 11 includes a piezoelectric element 12 (eg, a braid-shaped piezoelectric element 1, a cloth-shaped piezoelectric element 7), an amplification unit 13 that amplifies an electric signal output from the piezoelectric element 12 according to an applied pressure, and an amplification unit. Output means 14 for outputting the electric signal amplified by 13 and transmission means 15 for transmitting the electric signal output from the output means 14 to an external device (not shown). If this device 11 is used, the stress applied to the piezoelectric element 12 can be calculated by an external device (not shown) based on the electric signal output by the contact with the surface of the piezoelectric element 12, the pressure, and the shape change. The size and / or the applied position can be detected. Alternatively, the device 11 may be provided with a calculation means (not shown) for calculating the magnitude of the stress applied to the piezoelectric element 12 and / or the applied position based on the electric signal output from the output means 14. Good. It should be noted that whether the transmission method by the transmission unit 15 is wireless or wired may be appropriately determined according to the sensor to be configured.

  Further, not only the amplifying means, but also known signal processing means such as noise removing means and means for processing in combination with other signals can be used in combination. The order of connecting these means can be appropriately changed according to the purpose. Of course, the electric signal output from the piezoelectric element 12 may be directly processed to an external device and then processed.

  7 and 8 are schematic diagrams showing a configuration example of a device including the braided cord-like piezoelectric element according to the embodiment. The amplifying means 13 in FIGS. 7 and 8 corresponds to the one described with reference to FIG. 6, but the output means 14 and the transmitting means 15 in FIG. 6 are omitted in FIGS. 7 and 8. When constructing a device including the cloth-shaped piezoelectric element 7, the lead wire from the core portion 3 of the braided piezoelectric element 1 is connected to the input terminal of the amplification means 13, and the braided piezoelectric element 1 is connected to the ground terminal. The braid-like piezoelectric element different from the braid-like piezoelectric element 1 connected to the conductive layer 4 or the conductive fiber 10 of the cloth-like piezoelectric element 7 or the input terminal of the amplifying means 13 is connected. For example, as shown in FIG. 7, in the cloth-shaped piezoelectric element 7, the lead wire from the core portion 3 of the braided piezoelectric element 1 is connected to the input terminal of the amplification means 13, and the conductive layer 4 of the braided piezoelectric element 1 is connected. Ground. Instead of the conductive layer 4 of the braid-shaped piezoelectric element 1, the conductive fiber 10 that intersects and contacts the braid-shaped piezoelectric element 1 may be grounded. Further, for example, as shown in FIG. 8, when a plurality of braid-like piezoelectric elements 1 are arranged in the cloth-like piezoelectric element 7, the lead wire from the core portion 3 of one braid-like piezoelectric element 1 is connected to the input terminal of the amplifying means 13. And the lead wire from the core portion 3 of another braid-like piezoelectric element 1 arranged in line with the braid-like piezoelectric element 1 is grounded.

  Since the device 11 of the present invention is flexible and can be used in any of the string shape and the cloth shape, a very wide range of applications can be considered. Specific examples of the device 11 of the present invention include clothing such as hats, gloves and socks, supporters, handkerchief-shaped touch panels, surface pressure sensors for humans and animals, such as gloves and bands, There are sensors that detect bending, twisting, and expansion / contraction of joints in the shape of supporters. For example, when it is used for a person, it can be used as an interface for detecting contact and movement, collecting information on movement of joints and the like for medical applications, amusement applications, and moving lost tissues and robots. Besides, it can be used as a stuffed animal which imitates an animal or a humanoid, a surface pressure sensor of a robot, a sensor which detects bending, twisting, and expansion / contraction of joints. Besides, it can be used as a bedding such as sheets and pillows, a shoe sole, gloves, a chair, a rug, a bag, a surface pressure-sensitive sensor such as a flag, and a shape change sensor.

  Furthermore, since the device 11 of the present invention is in the shape of a braid or a cloth and has flexibility, it can be used as a surface pressure sensor or a shape change sensor by sticking or covering the entire surface or a part of the surface of any structure. You can

  Further, since the device 11 of the present invention can generate a sufficient electric signal only by rubbing the surface of the braid-shaped piezoelectric element 1, it can be used for a touch type input device such as a touch sensor or a pointing device. . In addition, since the position information and the shape information in the height direction of the measured object can be obtained by rubbing the surface of the measured object with the braided piezoelectric element 1, it can be used for surface shape measurement and the like.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

The fabric for the piezoelectric element was manufactured by the following method.
(Production of polylactic acid)
The polylactic acid used in the examples was produced by the following method.
0.005 parts by mass of tin octylate was added to 100 parts by mass of L-lactide (manufactured by Musashino Chemical Laboratory Co., Ltd., optical purity 100%), and 180 ° C. was added in a reactor equipped with a stirring blade under a nitrogen atmosphere. The reaction was carried out for 2 hours, and 1.2 times equivalent of phosphoric acid was added to tin octylate, and then the remaining lactide was removed under reduced pressure at 13.3 Pa to form chips, and poly-L-lactic acid (PLLA1) was obtained. . The obtained PLLA1 had a mass average molecular weight of 152,000, a glass transition point (Tg) of 55 ° C, and a melting point of 175 ° C.

(Piezoelectric fiber)
PLLA1 melted at 240 ° C. was discharged from a 24-hole cap at 20 g / min and collected at 887 m / min. The unstretched multifilament yarn was stretched 2.3 times at 80 ° C. and heat-set at 100 ° C. to obtain a 84 dTex / 24 filament multifilament uniaxially stretched yarn, which was designated as a piezoelectric fiber A.

(Conductive fiber)
Silver plated nylon manufactured by Mitsufuji Co., Ltd., product name "AGposs" 100d34f was used as the conductive fiber B, the conductive fiber 6 and the conductive fiber 10. The volume resistivity of this fiber was 1.1 × 10 ⁻³ Ω · cm.

(Insulating fiber)
Polyethylene terephthalate melted at 280 ° C. was discharged from a 24-hole cap at 45 g / min and collected at 800 m / min. This unstretched yarn was stretched 2.5 times at 80 ° C. and heat-set at 180 ° C. to obtain a 84 dTex / 24 filament multifilament stretched yarn, which was used as an insulating fiber 9.

(Braid-shaped piezoelectric element)
As the sample of Example 1, as shown in FIG. 1, the conductive fiber B was used as a core thread, and the eight piezoelectric fibers A were wound in a braid shape around the core thread to form an eight-strand braid, Further, the electrically conductive fiber 6 was wound around the piezoelectric fiber A in the sheath portion in the shape of an eight-strand braid to form the electrically conductive layer 4, and the braided piezoelectric element 1 was formed. Here, the winding angle α of the piezoelectric fiber A with respect to the fiber axis CL of the conductive fiber B was set to 45 °. The coverage of the conductive layer 4 of the sample of Example 1 was 100%. This braided piezoelectric element is cut, and the conductive fiber 6 constituting the conductive layer 4 having 10 mm at its end is loosened and separated from the piezoelectric fiber A and the conductive fiber B, and then SH connector manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. After the 0.4 mm long portion and 0.8 mm long claw portion are bent by using the contact as a signal metal terminal and the piezoelectric fiber A and the conductive fiber B remaining at the end of the braided piezoelectric element are grasped. A soldering iron was applied to the signal metal terminal to heat it, and the sheath portion of the grip portion was partially melted. The continuity between the core at the end of the braided piezoelectric element and the signal metal terminal was confirmed, and the excess braided piezoelectric element beyond the grip portion was cut. In addition, another SH connector contact manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. is used as a metal terminal for shielding, and a 0.4 mm long portion and a 0.8 mm long claw portion are bent to form a piezoelectric fiber A and a conductive fiber. The conductive fiber 6 separated from B was gripped. The conductive fiber 6 which was separated from the piezoelectric fiber A and could not be gripped by the shield metal terminal was cut off. The signal metal terminal and the shield metal terminal are inserted and fixed in an SH connector housing 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., and insulation is provided around the braid-shaped piezoelectric element 1 10 mm from the end face of the connector housing. The epoxy connector was adhered, and the SH connector and the braided piezoelectric element 1 were fixed. This braided piezoelectric element with a terminal was used as a braided piezoelectric element 101.

  As a sample of Example 2, as shown in FIG. 1, the conductive fiber B was used as a core thread, and the above-mentioned eight piezoelectric fibers A were wound in a braid shape around the core thread to form an eight-strand braid, Further, four insulating fibers 9 are wound in the right direction, one conductive fiber 6 and three insulating fibers 9 are wound in the left direction around the piezoelectric fiber A of the sheath part, and the conductive layer 4 in the shape of a braided string 4 is formed. Then, the braided piezoelectric element 1 was formed. Here, the winding angle α of the piezoelectric fiber A with respect to the fiber axis CL of the conductive fiber B was set to 45 °. The coverage of the conductive layer 4 of the sample of Example 2 was 25%. Similar to Example 1, the SH connector contact manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. was connected to the conductive fiber B as a signal metal terminal, and the conductive fiber 6 was connected to another SH connector manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. The contact is connected as a metal terminal for shield, and the metal terminal for signal and the metal terminal for shield are inserted and fixed in SH connector housing 2P made by Nippon Crimp Terminal Manufacturing Co., Ltd., and a braid of 10 mm from the end face of the connector housing An insulative epoxy-based adhesive was attached around the piezoelectric element 1 to fix the SH connector and the braided piezoelectric element 1. This braid-like piezoelectric element with a terminal was used as a braid-like piezoelectric element 102.

  As a sample of Example 3, the braid-like piezoelectric element 1 used in Example 1 and having no terminals connected thereto was cut, and the conductive fiber 6 constituting the conductive layer 4 having 10 mm at its end was disentangled to be electrically conductive with the piezoelectric fiber A. "Dotite" (registered trademark) D-363 (manufactured by Fujikura Kasei Co., Ltd.) as a conductive paste is attached to the piezoelectric fiber A and the conductive fiber B remaining at the ends of the braided piezoelectric element after being separated from the conductive fiber B. And solidify, and then using SH connector contacts made by Nippon Crimp Terminal Manufacturing Co., Ltd. as signal metal terminals, the 0.4 mm long part and 0.8 mm long claw part were bent, and the braid with the conductive paste attached The end of the piezoelectric element was grasped. Conduction was confirmed between the core at the other end of the braided piezoelectric element and the signal metal terminal. In addition, another SH connector contact manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. is used as a metal terminal for shielding, and a 0.4 mm long portion and a 0.8 mm long claw portion are bent to form a piezoelectric fiber A and a conductive fiber. The conductive fiber 6 separated from B was gripped, and the conductive fiber 6 separated from the piezoelectric fiber A could not be gripped by the shielding metal terminal and was cut off. The above-mentioned signal metal terminal and shield metal terminal are inserted and fixed in an SH connector housing 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., and epoxy is provided around the braid-shaped piezoelectric element 1 10 mm from the end surface of the connector housing. A system adhesive was attached to fix the SH connector and the braided piezoelectric element 1. This braided piezoelectric element with a terminal was used as a braided piezoelectric element 103.

  As a sample of Example 4, the braided piezoelectric element 1 used in Example 1 and having no terminals connected thereto was cut, and the conductive fiber 6 constituting the conductive layer 4 having 10 mm at its end was disentangled to be electrically conductive with the piezoelectric fiber A. "Dotite" (registered trademark) D-363 (manufactured by Fujikura Kasei Co., Ltd.) as a conductive paste is attached to the piezoelectric fiber A and the conductive fiber B remaining at the ends of the braided piezoelectric element after being separated from the conductive fiber B. Then, 2 mm was inserted into the center contact of the SMA-P type coaxial connector and solidified to form a signal metal terminal, and conduction between the core at the other end of the braided piezoelectric element and the signal metal terminal was confirmed. . In addition, the metal sheath of the SMA-P type coaxial connector is used as a metal terminal for shielding, and the conductive fiber 6 separated from the piezoelectric fiber A and the conductive fiber B is gripped and connected by a sleeve to fix the conductive fiber 6 for shielding. The conductive fiber 6 which could not be held by the metal terminal and was separated from the piezoelectric fiber A was cut off. As described above, the braided piezoelectric element with a terminal in which the signal metal terminal and the shield metal terminal are integrated via the insulator is referred to as a braided piezoelectric element 104. The SMA-P connector used in this example has a structure in which the metal terminal for shield (exterior) completely covers the metal terminal for signal (center contact) in the left side view.

  As a sample of Example 5, as shown in FIG. 8, two insulating fibers 9 and two braided piezoelectric elements 1 (the same as the sample of Example 1 in which the terminals are not connected) are arranged on the warp, and the weft is made of insulating fiber. 9 and conductive fibers 10 were alternately arranged to produce a plain woven fabric, which was used as a fabric piezoelectric element 7. After the conductive fibers 6 constituting the conductive layer 4 of 10 mm from the ends of the two braided piezoelectric elements 1 in the cloth piezoelectric element 7 are disentangled and separated from the piezoelectric fiber A and the conductive fiber B, the piezoelectric fiber Into the exposed portion of A, the fork-shaped metal portions of 2 poles of the 10 poles of the XG pressure contact connector manufactured by OMRON CORPORATION were respectively inserted to serve as the metal terminals for signals, and at the same time, from the piezoelectric fiber A and the conductive fiber B. The separated conductive fibers 6 were put together, and the conductive fiber bundle was inserted into a fork-shaped metal portion of one of the 10 contact terminals of the pressure contact connector to form a shield metal terminal. Further, the braid-shaped piezoelectric element was sandwiched and fixed by the upper portion of the connector housing fixed to the metal portion and the lower portion forming a pair therewith. Conduction between the end core of the two braided piezoelectric elements 1 and the two-pole signal metal terminals, and between the conductive layer 4 of the two braided piezoelectric elements 1 and the one-pole shield metal terminals. And the insulation between the two-pole signal metal terminal and the one-pole shield metal terminal was confirmed. The two braid-like piezoelectric elements with metal terminals for signals were referred to as braid-like piezoelectric elements 105-1 and 105-2, respectively. The braided piezoelectric element was fixed by the warp of the plain woven cloth, and the distance between the signal metal terminal and the warp of the plain woven cloth was 0.1 mm.

  As a sample of Example 6, the braid-shaped piezoelectric element 1 used in Example 1 and having no terminals connected thereto was cut, and the conductive fiber 6 constituting the conductive layer 4 having a terminal length of 10 mm was disentangled to be electrically conductive with the piezoelectric fiber A. After separating from the fiber B and further loosening the piezoelectric fiber A at the end and exposing the core portion by 1 mm, the sheath portion is removed by using SH connector contact manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. as a signal metal terminal. The braided piezoelectric element was gripped by bending the claw so that the claw part having a length of 0.4 mm grips the non-existing part and the claw part having a length of 0.8 mm grips the exposed core part. Conduction was confirmed between the core at the other end of the braided piezoelectric element and the signal metal terminal. In addition, another SH connector contact manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. is used as a metal terminal for shielding, and a 0.4 mm long portion and a 0.8 mm long claw portion are bent to form a piezoelectric fiber A and a conductive fiber. The conductive fiber 6 separated from B was gripped, and the conductive fiber 6 separated from the piezoelectric fiber A could not be gripped by the shielding metal terminal and was cut off. The signal metal terminal and the shield metal terminal were inserted and fixed in an SH connector housing 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. This braid-like piezoelectric element with a terminal was used as a braid-like piezoelectric element 106.

  As a sample of Comparative Example 1, the braided piezoelectric element 1 used in Example 1 and having no terminals connected thereto was cut, and the conductive fiber 6 constituting the conductive layer 4 having a terminal length of 10 mm was disentangled to be electrically conductive with the piezoelectric fiber A. "Dotite" (registered trademark) D-363 (manufactured by Fujikura Kasei Co., Ltd.) as a conductive paste is attached to the piezoelectric fiber A and the conductive fiber B remaining at the ends of the braided piezoelectric element after being separated from the conductive fiber B. And solidify, and then using SH connector contacts made by Nippon Crimp Terminal Manufacturing Co., Ltd. as signal metal terminals, the 0.4 mm long part and 0.8 mm long claw part were bent, and the braid with the conductive paste attached The end of the piezoelectric element was grasped. Conduction was confirmed between the core at the other end of the braided piezoelectric element and the signal metal terminal. In addition, another SH connector contact manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. is used as a metal terminal for shielding, and a 0.4 mm long portion and a 0.8 mm long claw portion are bent to form a piezoelectric fiber A and a conductive fiber. The conductive fiber 6 separated from B was gripped, and the conductive fiber 6 separated from the piezoelectric fiber A could not be gripped by the shield metal terminal and was cut off. The above-mentioned metal terminal for signal and metal terminal for shield are respectively inserted and fixed in two SH connector housings 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., and around the braid-shaped piezoelectric element 1 10 mm from the end surface of the connector housing. An epoxy-based adhesive was attached to each of the SH connectors and the braided piezoelectric element 1 was fixed to each SH connector. This braid-like piezoelectric element with a terminal was used as a braid-like piezoelectric element 201.

  As a sample of Comparative Example 2, as in Example 1, the conductive fiber B was used as a core thread, and the eight piezoelectric fibers A were wound in a braid shape around the core thread to form an eight-strand braid. However, the braided piezoelectric element was formed without forming the conductive layer 4. Here, the winding angle α of the piezoelectric fiber A with respect to the fiber axis CL of the conductive fiber B was set to 45 °. "Dotite" (registered trademark) D-363 (manufactured by Fujikura Kasei Co., Ltd.) as a conductive paste is adhered to the piezoelectric fiber A and the conductive fiber B at the end of the braided piezoelectric element to solidify them, and then manufactured by Nippon Crimping Terminal Co., Ltd. Using a SH connector contact manufactured by Co., Ltd. as a signal metal terminal, a 0.4 mm long portion and a 0.8 mm long claw portion were bent, and the end of the braided piezoelectric element to which the conductive paste was attached was grasped. Conduction was confirmed between the core at the other end of the braided piezoelectric element and the signal metal terminal. The above-mentioned metal terminal for signal is inserted and fixed in SH connector housing 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., and epoxy adhesive is attached around the braid-shaped piezoelectric element 1 10 mm from the end surface of the connector housing. , SH connector and braided piezoelectric element 1 were fixed. This braided piezoelectric element with a terminal was used as a braided piezoelectric element 202.

(Performance evaluation and evaluation results)
The performance evaluation and the evaluation results of the braided piezoelectric elements 101, 102, 103, 104, 105-1, 105-2, 106, 201, 202 are as follows.

(Example 1)
The SH connector housing manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., to which the metal terminals for signals and the metal terminals for shielding in the braided piezoelectric element 101 are fixed, is connected to the SH connector base 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. , The signal metal terminal is connected to an oscilloscope (Yokogawa Denki Co., Ltd. digital oscilloscope DL6000 series, product name "DL6000") via a 1000-fold amplification circuit for wiring to shield the braided piezoelectric element 1. Connected so that the metal terminal is grounded. The connection to the braided piezoelectric element 101, the measuring circuit, and the ground was made collectively by the SH connector. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 0% when the sheath tissue was unraveled and separated from the core portion.
As a result of bending the braid-like piezoelectric element 101 by 90 degrees, a potential difference of about 100 mV is detected by the oscilloscope as an output from the braid-like piezoelectric element 101, and a sufficiently large electric signal can be detected by the deformation of the braid-like piezoelectric element 1. Was confirmed. Further, the noise signal in the stationary state was 20 mV, and the S / N ratio was 5, indicating that the noise signal was sufficiently suppressed.

(Example 2)
The SH connector housing manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., to which the signal metal terminals and the shield metal terminals in the braided piezoelectric element 102 are fixed, is connected to the SH connector base 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. , The signal metal terminal is connected to an oscilloscope (Yokogawa Denki Co., Ltd. digital oscilloscope DL6000 series, product name "DL6000") via a 1000-fold amplification circuit for wiring to shield the braided piezoelectric element 1. Connected so that the metal terminal is grounded. The connection to the braided piezoelectric element 102, the measurement circuit, and the ground was made collectively by the SH connector. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 0% when the sheath tissue was unraveled and separated from the core portion.
As a result of bending the braid-shaped piezoelectric element 102 by 90 degrees, a potential difference of about 100 mV is detected by the oscilloscope as an output from the braid-shaped piezoelectric element 102, and a sufficiently large electric signal can be detected by the deformation of the braid-shaped piezoelectric element 1. Was confirmed. Further, the noise signal in the stationary state was 20 mV, and the S / N ratio was 5, indicating that the noise signal was sufficiently suppressed.

(Example 3)
The SH connector housing manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., to which the metal terminals for signals and the metal terminals for shielding in the braided piezoelectric element 103 are fixed, is connected to the SH connector base 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. , The signal metal terminal is connected to an oscilloscope (Yokogawa Denki Co., Ltd. digital oscilloscope DL6000 series, product name "DL6000") via a 1000-fold amplification circuit for wiring to shield the braided piezoelectric element 1. Connected so that the metal terminal is grounded. The connection to the braided piezoelectric element 103, the measuring circuit, and the ground was made collectively by the SH connector. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 0% when the sheath tissue was unraveled and separated from the core portion.
As a result of bending the braid-like piezoelectric element 103 by 90 degrees, a potential difference of about 100 mV is detected by the oscilloscope as an output from the braid-like piezoelectric element 103, and a sufficiently large electric signal can be detected by the deformation of the braid-like piezoelectric element 1. Was confirmed. Further, the noise signal in the stationary state was 20 mV, and the S / N ratio was 5, indicating that the noise signal was sufficiently suppressed.

(Example 4)
The SMA-P type coaxial connector to which the signal metal terminal and the shield metal terminal in the braided piezoelectric element 104 are fixed is connected to the SMA-J type coaxial connector, and the signal metal terminal is connected to an oscilloscope (Yokogawa). It is connected to a digital oscilloscope DL6000 series (trade name "DL6000" manufactured by Denki Co., Ltd.) via a wiring via a 1000-fold amplification circuit so that the metal terminal for shielding of the braided piezoelectric element 1 is grounded. Connected The connection to the braided piezoelectric element 104, the measuring circuit, and the ground was made collectively by the SMA type connector. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 0% when the sheath tissue was unraveled and separated from the core portion.
As a result of bending the braid-like piezoelectric element 104 by 90 degrees, a potential difference of about 100 mV is detected by the oscilloscope as an output from the braid-like piezoelectric element 104, and a sufficiently large electric signal can be detected by the deformation of the braid-like piezoelectric element 1. Was confirmed. In addition, the noise signal in the stationary state was 16 mV, and the S / N ratio was 6, indicating that the noise signal was sufficiently suppressed.

(Example 5)
Connect the Omron Co., Ltd. XG insulation displacement connector, to which the braid-like piezoelectric element 105-1 and the braid-like piezoelectric element 105-2 are fixed to the signal metal terminal and the shield metal terminal, to the pin header of 2 rows x 5 rows. The metal terminal for signal is connected to an oscilloscope (digital oscilloscope DL6000 series product name "DL6000" manufactured by Yokogawa Electric Co., Ltd.) via a 1000 times amplification circuit, and the braided piezoelectric element 1 is shielded. The metal terminal was connected so that it would be grounded. The braid-like piezoelectric element 105-1 and the braid-like piezoelectric element 105-2, the measurement circuit, and the ground were collectively connected by an XG pressure contact connector. In addition, at the end of the fork-shaped metal portion of the signal metal terminal, the piezoelectric fiber which is loosened from the sheath tissue and separated from the core portion has no braid-like piezoelectric element 105-1 and braid-like piezoelectric element 105-2. %Met.
As a result of bending the braid-like piezoelectric element 105-1 and the braid-like piezoelectric element 105-2 by bending the cloth-like piezoelectric element 7 as an output from the braid-like piezoelectric element 105-1 and the braid-like piezoelectric element 105-2. A potential difference of about 100 mV was detected by an oscilloscope, respectively, and it was confirmed that a sufficient magnitude of electric signal could be detected by the deformation of the braid-shaped piezoelectric element 1. Further, the noise signal in the stationary state was 20 mV, and the S / N ratio was 5, indicating that the noise signal was sufficiently suppressed.

(Example 6)
The SH connector housing manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., to which the metal terminals for signals and the metal terminals for shielding in the braided piezoelectric element 106 are fixed, is connected to the SH connector base 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. , The signal metal terminal is connected to an oscilloscope (Yokogawa Denki Co., Ltd. digital oscilloscope DL6000 series, product name "DL6000") via a 1000-fold amplification circuit for wiring to shield the braided piezoelectric element 1. Connected so that the metal terminal is grounded. The connection to the braided piezoelectric element 106, the measurement circuit, and the ground was made collectively by the SH connector. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 75% in which the tissue of the sheath portion was released and separated from the core portion.
As a result of bending the braid-like piezoelectric element 106 by 90 degrees, a potential difference of about 100 mV was detected by the oscilloscope as an output from the braid-like piezoelectric element 106, but noise with an amplitude of about 30 mV was superimposed on the signal near the peak. It was confirmed that noise was generated by the bending operation. Further, the noise signal in the stationary state was 20 mV, and the S / N ratio was 5, indicating that the noise signal was sufficiently suppressed.

(Comparative Example 1)
An SH connector housing manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., in which the metal terminals for signals in the braided piezoelectric element 201 are fixed, and an SH connector housing manufactured by Japan Crimp Terminal Manufacturing, Inc., in which the metal terminals for shielding are fixed, Each is connected to SH connector base 2P made by Nippon Crimp Terminal Manufacturing Co., Ltd., and the metal terminal for signal is amplified 1000 times through wiring to the oscilloscope (Yokogawa Electric Co., Ltd. digital oscilloscope DL6000 series product name "DL6000"). It was connected via a circuit, and was connected so that the shield metal terminal of the braided piezoelectric element 1 was grounded. Since the braid-like piezoelectric element 201, the measuring circuit and the ground were separately connected by two sets of SH connectors, the work was complicated and the conductive fiber 6 pulled by the shielding metal terminal was frayed. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 0% when the sheath tissue was unraveled and separated from the core portion.
As a result of bending the braid-like piezoelectric element 201 by 90 degrees, a potential difference of about 100 mV is detected by an oscilloscope as an output from the braid-like piezoelectric element 201, and a sufficiently large electric signal can be detected by the deformation of the braid-like piezoelectric element 1. Was confirmed. In addition, the noise signal in the stationary state was 25 mV, and the S / N ratio was 4, and the noise signal could not be sufficiently suppressed.

(Comparative example 2)
The SH connector housing manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., to which the signal metal terminals in the braided piezoelectric element 202 are fixed, is connected to the SH connector base 2P manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd. Was connected to an oscilloscope (digital oscilloscope DL6000 series trade name “DL6000” manufactured by Yokogawa Electric Corp.) via a 1000-fold amplification circuit via a wire, and the noise signal in the stationary state was 1000 mV. The braid-like piezoelectric element 202 was bent 90 degrees, but the noise signal was large and the electric signal derived from the bending could not be discriminated. In addition, at the end of the gripped portion of the signal metal terminal, the piezo-electric fiber was 0% when the sheath tissue was unraveled and separated from the core portion.

A piezoelectric fiber B conductive fiber 1 braided piezoelectric element 2 sheath portion 3 core portion 4 conductive layer 6 conductive fiber 7 cloth type piezoelectric element 8 cloth 9 insulating fiber 10 conductive fiber 11 device 12 piezoelectric element 13 amplifying means 14 Output means 15 Transmission means CL Fiber axis α Wrapping angle 100 Plain weave

Claims (16)

A core formed of conductive fibers,
A sheath portion formed of a braided piezoelectric fiber so as to cover the core portion,
A conductive layer provided around the sheath,
A piezoelectric element including: a signal metal terminal connected and fixed to the core portion; and a shield metal terminal connected and fixed to the conductive layer, the signal metal terminal and the signal metal terminal A piezoelectric element in which a metal terminal for shielding is fixed to each other via an insulator.   The piezoelectric element according to claim 1, wherein a coverage of the sheath with the conductive layer is 25% or more.   The piezoelectric element according to claim 1, wherein the conductive layer is formed of fibers.   The piezoelectric element according to any one of claims 1 to 3, wherein the shield metal terminal covers and holds the signal metal terminal via an insulator. The signal metal terminal is connected and fixed in one of the following modes A and B, and the piezoelectric element is fixed by the signal metal terminal or a component fixed to the signal metal terminal. Any of claims 1 to 4, wherein at the end of the portion, the piezo-electric fibers of the sheath that are disentangled and separated from the core have a portion that is less than 20% of the total piezoelectric fibers of the sheath. 2. The piezoelectric element according to item 1.
A) A part of the signal metal terminal grips a part having a length of 0.5 mm or more of a fiber constituting the end part of the piezoelectric element, and the grip part or a place within 1 mm from the grip part, A state in which the core portion of the piezoelectric element and the signal metal terminal are electrically connected and fixed directly or indirectly through a conductive material B) A part of the signal metal terminal is fork-shaped or needle-shaped The fork-shaped portion or the needle-shaped portion is connected to the conductive fiber of the core portion directly or indirectly through a conductive material while being in contact with the sheath portion of the piezoelectric element, and 10 mm from this connection point. In a place within, a state in which the piezoelectric element is fixed to the signal metal terminal by another portion of the signal metal terminal or a part fixed to the signal metal terminal.   6. A part or all of the piezoelectric fibers of the sheath portion within 5 mm from a connecting portion between the core portion and the signal metal terminal loses the fiber shape and is fused. The piezoelectric element according to 1.   The surface of the sheath is provided with a conductive material made of solder or a conductive paste and electrically connected to the core, and the conductive material provided on the surface of the sheath and the signal metal. The piezoelectric element according to any one of claims 1 to 6, wherein the core portion and the signal metal terminal are indirectly electrically connected by contact with the terminal.   A piezoelectric element comprising a cloth including the piezoelectric element according to claim 1, wherein the signal metal terminal or the shield metal terminal is within a length of 10 mm from a portion fixed to the piezoelectric element. Within the range, at least a part of the piezoelectric element is fixed to the cloth-like substrate.   Two or more piezoelectric elements according to any one of claims 1 to 7 are arranged substantially in parallel, and two or more signal metal terminals connected to each piezoelectric element are provided in one connector housing. The piezoelectric element according to any one of claims 1 to 8, which is put together and can be collectively connected to another connector.   The piezoelectric element according to any one of claims 1 to 7, wherein two or more of the piezoelectric elements according to any one of claims 1 to 7 are arranged substantially in parallel as a part of threads constituting a woven fabric or a knitted fabric. Piezoelectric fiber contains polylactic acid as the main component,
The piezoelectric element according to claim 1, wherein a winding angle of the piezoelectric fiber with respect to the conductive fiber is 15 ° or more and 75 ° or less. The total fineness of the piezoelectric fibers is 1 to 20 times the total fineness of the conductive fibers,
The piezoelectric element according to claim 1.   The piezoelectric element according to any one of claims 1 to 12, wherein a fineness per one of the piezoelectric fibers is 1/20 times or more and 2 times or less of a total fineness of the conductive fibers.   The piezoelectric element according to claim 8, further comprising a conductive fiber that intersects and contacts at least a part of the piezoelectric element.   15. The piezoelectric element of claim 14, wherein the conductive fibers make up 30% or more of the fibers that intersect the piezoelectric element. The piezoelectric element according to any one of claims 1 to 15,
An amplifying unit that amplifies an electric signal output from the piezoelectric element according to the applied pressure,
Output means for outputting the electric signal amplified by the amplifying means,
Device with.

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