JP5694856B2 - Flexible electrode structure and transducer comprising an electrode having a flexible electrode structure - Google Patents

Description

  The present invention relates to a flexible electrode structure suitable for an electrode such as a flexible transducer.

  Development of highly flexible, small and lightweight transducers using polymer materials such as elastomers is underway. Examples of the transducer include an actuator, a sensor, and a power generation element that convert mechanical energy and electrical energy, or a speaker and microphone that convert acoustic energy and electrical energy.

  For example, Patent Document 1 discloses a capacitive sensor including a dielectric layer, a front side electrode, a back side electrode, a detection unit, a front side wiring, and a back side wiring. The front side electrodes have a belt shape and are arranged in a plurality of rows. Similarly, the back side electrodes have a strip shape and are arranged in a plurality of rows. A plurality of detection units are formed by the front side electrode and the back side electrode facing each other through the dielectric layer. When a load is applied to the capacitance type sensor, the thickness of the detection unit corresponding to the portion to which the load is applied, that is, the distance between the front side electrode and the back side electrode changes. Thereby, the electrostatic capacitance of a detection part changes. The capacitance type sensor detects the surface pressure distribution based on the change in the capacitance.

  In the capacitive sensor disclosed in this document, the dielectric layer is made of an elastomer. Therefore, in order not to restrict the elastic deformation of the dielectric layer, the front side electrode and the back side electrode (hereinafter collectively referred to as “electrode”) are each formed from a carbon paste containing a polymer for elastomer and carbon black. Yes.

JP 2010-43881 A JP 2005-317638 A JP 2010-21371 A JP 2010-153821 A

The electrical resistance of the object is calculated from the following equation (1).
r = ρL / S (1)
In formula (1), r is electrical resistance, ρ is volume resistivity, L is length, and S is cross-sectional area (thickness × width). As is clear from the equation (1), when the cross-sectional area is constant, the electrical resistance r increases as the length L of the object increases. In the capacitance type sensor described above, the electrode has a strip shape. For this reason, the electrical resistance of an electrode becomes large, so that it is far from the connection part to which wiring is connected. Therefore, there is a possibility that the electric resistance of the electrode in the detection unit is different due to the distance from the connection unit. In this case, the detection value of the capacitance changes for each detection unit, and the measurement accuracy of the surface pressure distribution may be lowered.

  Moreover, the volume resistivity of carbon black is larger than that of metals such as silver. For this reason, when an electrode is formed from carbon paste, the variation in electrical resistance due to the difference in distance from the connecting portion increases. Therefore, the above problem that the detection value of the capacitance changes for each detection unit becomes more prominent.

  On the other hand, a silver paste in which a binder is filled with silver powder is known as a wiring material. The electric resistance of the silver wiring formed from the silver paste is small. For this reason, the variation in the electrical resistance in the length direction is not so problematic. However, silver powder is more expensive than carbon black. For this reason, when the electrode which occupies a big area from silver paste is formed, cost will become high. The silver paste is highly filled with silver powder. For this reason, the electrode formed from the silver paste is poor in flexibility. Therefore, if it expands greatly, a crack will generate | occur | produce and an electrical resistance will increase remarkably. In addition, the electrode cannot follow the expansion and contraction of the dielectric layer, which may hinder the movement of the dielectric layer.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the flexible electrode structure which is comparatively cheap, can be expanded-contracted, and has a small electrical resistance distribution. Another object of the present invention is to provide a relatively inexpensive and high-performance transducer by using the flexible electrode structure as an electrode.

  (1) In order to solve the above-mentioned problem, a flexible electrode structure of the present invention includes a flexible conductive layer containing an elastomer and conductive carbon powder, and is disposed on the surface of the flexible conductive layer, and has a volume resistance higher than that of the flexible conductive layer. A wiring portion having a small rate, and the wiring portion is arranged so that variation in electric resistance in the surface direction of the flexible conductive layer is reduced.

  In the flexible electrode structure of the present invention, the flexible conductive layer includes an elastomer and conductive carbon powder. Therefore, the electrical resistance increases as the distance from the connection portion of the wiring becomes longer. However, according to the flexible electrode structure of the present invention, the wiring part having a smaller volume resistivity than the flexible conductive layer is disposed on the surface of the flexible conductive layer. The wiring portion is arranged so that variation in electric resistance in the surface direction of the flexible conductive layer is reduced. Thereby, the problem that the electric resistance is different depending on the portion of the flexible conductive layer is solved, and high conductivity can be realized as the entire flexible electrode structure. As described above, according to the flexible electrode structure of the present invention, it is possible to realize a flexible, highly conductive electrode having a substantially uniform electric resistance in the plane direction by using a relatively inexpensive conductive carbon powder.

Here, the volume resistivity of the wiring part is desirably 1 × 10 ⁻⁵ Ω · cm or less. Moreover, when the flexibility of the flexible conductive layer is high, the followability to deformation of a substrate such as a dielectric layer is improved. For example, the elongation percentage of the flexible conductive layer is desirably 150% or more. In this specification, the value of elongation at break measured by a tensile test (JIS K6251 (2004)) is adopted as the elongation.

  The volume resistivity of the wiring part is smaller than the volume resistivity of the flexible conductive layer. For example, the wiring part can be formed from a conductive paste in which a binder is highly filled with metal powder or conductive carbon powder. Therefore, the wiring portion may be less flexible than the flexible conductive layer. However, according to the flexible electrode structure of the present invention, the wiring portion is disposed on the surface of the flexible conductive layer. For this reason, the flexibility of the wiring part is low, and when it is extended, even if a crack occurs in a part of the wiring part and the conduction is cut off, the conduction can be ensured through the flexible conductive layer that is in contact. That is, even when the wiring portion is disconnected, a part of the conduction path is bypassed to the flexible conductive layer, so that the conductivity as the electrode is ensured. Therefore, the flexible electrode structure of the present invention is excellent in durability.

  Incidentally, Patent Document 2 discloses a wiring board in which a silver paste wiring circuit is formed on a carbon paste circuit. Patent Document 3 discloses a wiring board in which a wiring made of silver paste is covered with a protective film made of a conductive paste containing carbon powder. These are techniques regarding the structure of the wiring. In other words, in the wiring board, migration of silver wiring is suppressed and insulation between adjacent wirings is only ensured. Therefore, there is no idea of suppressing variation in electric resistance in the electrode.

  Patent Document 4 discloses a conductive film including a conductive layer and an elastomer protective layer that covers the conductive layer. The protective layer protects and reinforces the conductive layer. Although there is a description that carbon black may be contained in the protective layer, this is to suppress migration when the conductive film is used as a wiring. As described above, Patent Document 4 also has no idea of suppressing variation in electrical resistance in the electrodes.

  (2) Preferably, in the configuration of (1), the area of the wiring portion is preferably smaller than the area of the flexible conductive layer.

  According to this configuration, it is difficult to restrict the expansion and contraction of the flexible conductive layer even if the wiring portion is inflexible. Moreover, when using a metal powder with high cost for a wiring part, the usage-amount of metal powder can be reduced only for the part with a small area. Thereby, cost can be reduced and a cheaper electrode can be realized.

  (3) Preferably, in the configuration of (1) or (2), the flexible conductive layer has a strip shape, and the wiring portion extends at least in the longitudinal direction of the flexible conductive layer. Good.

  When the flexible conductive layer has a strip shape, as described above, the electrical resistance increases as the distance from the connection portion of the wiring increases. That is, variation in electrical resistance increases in the longitudinal direction of the flexible conductive layer. According to this configuration, the wiring portion extends at least in the longitudinal direction of the flexible conductive layer. For this reason, even when the length of the flexible conductive layer is long, the distance to the wiring portion can be shortened. Thereby, the dispersion | variation in the electrical resistance at least in the longitudinal direction of the flexible conductive layer can be suppressed.

  (4) Preferably, in any one of the above configurations (1) to (3), the wiring portion may include a binder and metal powder.

  In general, the volume resistivity of metals is small. Therefore, according to this configuration, a wiring portion having a volume resistivity smaller than that of the flexible conductive layer can be easily formed. In addition, when a conductive paste containing a binder and metal powder is used, a thin-film wiring portion can be easily formed into various shapes using a printing method or the like.

  The metal powder may be appropriately selected from powders of silver, gold, copper, nickel, rhodium, palladium, chromium, titanium, platinum, iron, and alloys thereof. A metal powder may be used individually by 1 type, and 2 or more types may be mixed and used for it. Among these, silver is preferable because of its small volume resistivity. Accordingly, silver powder or silver alloy powder may be used as the metal powder.

  (5) Preferably, in any one of the configurations (1) to (4), the flexible conductive layer and the wiring portion are both formed by a printing method.

  According to the printing method, even when the flexible conductive layer and the wiring portion are thin or have a large area, they can be easily formed. Further, in the printing method, it is easy to separate the applied part and the non-applied part. For this reason, even if a flexible conductive layer and a wiring part are a thin wire | line or a complicated shape, it can form easily. Examples of the printing method include inkjet printing, flexographic printing, gravure printing, screen printing, pad printing, and lithography. Among these, the screen printing method is preferable because a highly viscous paint can be used and the thickness of the coating film can be easily adjusted.

  (6) A transducer according to the present invention includes a dielectric layer made of an elastomer or a resin, and a plurality of electrodes disposed via the dielectric layer, wherein the plurality of electrodes are the above-described (1) to (5). The flexible electrode structure of the present invention having any configuration is provided.

  The electrode of the transducer of the present invention has the flexible electrode structure of the present invention. Therefore, the electrode is relatively inexpensive and has high conductivity. In addition, variation in electric resistance is small in the surface direction of the electrode. For this reason, according to the transducer of this invention, the fall of the detection accuracy etc. resulting from the distribution of the electrical resistance of an electrode are small. Further, when the electrode is extended following the deformation of the dielectric layer, even if a crack is generated in a part of the wiring portion and the conduction is cut off, the conduction can be ensured through the flexible conductive layer that is in contact with the electrode. . That is, even if the wiring part is disconnected, conduction is ensured by partly bypassing the conductive path to the flexible conductive layer. Therefore, the transducer of the present invention is excellent in durability.

  (7) Preferably, in the configuration of (6) above, the plurality of electrodes include a plurality of front electrodes arranged on the front side of the dielectric layer, and a plurality of back electrodes arranged on the back side of the dielectric layer; A plurality of detection portions formed by the flexible conductive layer of the front electrode and the flexible conductive layer of the back electrode facing each other through the dielectric layer, the front electrode and the back electrode In each case, it is preferable that the wiring unit is a capacitance type sensor that is arranged so as to overlap at least the detection unit and can detect a surface pressure distribution from a change in capacitance of the detection unit.

  In the capacitive sensor of this configuration, the detection unit is arranged using the intersection of the front side electrode and the back side electrode. The wiring part is arranged so as to overlap at least the detection part. For this reason, in any detection part, the distance with a wiring part is small. That is, the difference in electrical resistance between the detection units is small. Therefore, the variation in the detected capacitance value due to the position of the detection unit is small. Therefore, in the capacitive sensor of this configuration, the measurement accuracy of the surface pressure distribution is high.

It is an upper surface penetration figure of the capacitive type sensor of a first embodiment. It is II-II sectional drawing of FIG. It is a top view of front side electrode 01Y and front side wiring 01y in the same capacitance type sensor. It is a schematic diagram of the lamination process in the manufacturing method of the same capacitive sensor. It is sectional drawing of the capacitive type sensor of 2nd embodiment. It is sectional drawing of the capacitive type sensor of 3rd embodiment. It is a top view of the front side electrode 01Y in the electrostatic capacitance type sensor of 4th embodiment. It is a top view of front side electrode 01Y in the capacitive sensor of 5th embodiment. It is a top view of front side electrode 01Y in the capacitive sensor of 6th embodiment. It is a top view of front side electrode 01Y in the capacitive type sensor of 7th embodiment. It is a top view of the example of an electrode which consists of a flexible electrode structure of the present invention.

  Next, embodiments of the flexible electrode structure and the transducer of the present invention will be described.

<First embodiment>
[Configuration of capacitive sensor]
An embodiment of a capacitive sensor will be described as an example of the transducer of the present invention. The flexible electrode structure of the present invention is embodied as an electrode of the same capacitive sensor. First, the configuration of the capacitive sensor of this embodiment will be described. FIG. 1 shows a top transparent view of the capacitive sensor of this embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 shows a top view of the front electrode 01Y and the front wiring 01y in the same capacitance type sensor. In FIG. 1, the member laminated | stacked on the front and back direction (thickness direction) is permeate | transmitted and shown. In addition, in the symbol “AOOΔΔ” of the detection unit, the upper two digits “OO” correspond to the back-side electrodes 01X to 06X. The last two digits “ΔΔ” correspond to the front electrodes 01Y to 06Y.

  As shown in FIGS. 1 and 2, the capacitive sensor 1 of the present embodiment includes a sensor body 2 and a calculation unit 3. The sensor body 2 includes a dielectric layer 20, a front side member 21, and a back side member 22.

  The dielectric layer 20 is made of urethane foam and has a rectangular sheet shape. The front side member 21 is disposed on the front side (upper side) of the dielectric layer 20. The back side member 22 is disposed on the back side (lower side) of the dielectric layer 20. The front side member 21 and the back side member 22 are laminated with the dielectric layer 20 interposed therebetween.

  The front side member 21 includes a base film 210, a cover film 211, front side electrodes 01Y to 06Y, front side wirings 01y to 06y, and a front side connector 212. The base film 210 is made of polyethylene terephthalate (PET) and has a sheet shape. Similarly, the cover film 211 is made of PET and has a sheet shape. The base film 210 and the cover film 211 extend in the XY direction (front / rear / left / right direction). The shape of the base film 210 and the shape of the cover film 211 are the same. The base film 210 and the cover film 211 are laminated with the front side electrodes 01Y to 06Y and the front side wirings 01y to 06y interposed therebetween.

  A total of six front side electrodes 01Y to 06Y are arranged between the base film 210 and the cover film 211. The front side electrodes 01Y to 06Y each have a strip shape. The front side electrodes 01Y to 06Y each extend in the Y direction (front-rear direction). The front-side electrodes 01Y to 06Y are arranged so as to be substantially parallel to each other in the X direction (left-right direction) with a predetermined interval. As shown in FIG. 3, the front side electrodes 01Y to 06Y each have a flexible conductive layer 23Y and a wiring portion 24Y. The front side electrodes 01Y to 06Y have the flexible electrode structure of the present invention.

The flexible conductive layer 23Y has a strip shape. The flexible conductive layer 23Y is formed including acrylic rubber and carbon black. The volume resistivity of the flexible conductive layer 23Y is about 1 Ω · cm, and the elongation is 150%. The wiring portion 24Y has a linear shape extending from the front end to the rear end of the flexible conductive layer 23Y. The wiring portion 24Y is disposed at the center of the surface (upper surface) of the flexible conductive layer 23Y. The wiring portion 24Y is arranged so that variation in electrical resistance in the length direction (front-rear direction) of the flexible conductive layer 23Y is reduced. The wiring part 24Y is formed including a polyester resin and silver powder. The volume resistivity of the wiring part 24Y is about 1 × 10 ⁻⁶ Ω · cm, and the elongation is less than 1%.

  A total of six front side wirings 01y to 06y are arranged between the base film 210 and the cover film 211. Each of the front-side wirings 01y to 06y has a linear shape. The front connector 212 is disposed at the left front corner of the front member 21. The front connector 212 is electrically connected to the calculation unit 3. The front wirings 01y to 06y connect the front end portions of the front electrodes 01Y to 06Y and the front connector 212, respectively. As illustrated in FIG. 3, the front side wirings 01y to 06y each include a flexible conductive layer 23y and a wiring part 24y.

  The flexible conductive layer 23y has a linear shape. The flexible conductive layer 23y is formed to include acrylic rubber and carbon black, like the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y. That is, the flexible conductive layer 23Y and the flexible conductive layer 23y are continuously formed. The wiring part 24y has a linear shape. The width of the wiring part 24y is slightly smaller than the width of the flexible conductive layer 23y. The wiring part 24y is formed by including a polyester resin and silver powder, similarly to the wiring part 24Y of the front side electrodes 01Y to 06Y. That is, the wiring part 24Y and the wiring part 24y are formed continuously.

  The back side member 22 includes a base film 220, a cover film 221, back side electrodes 01X to 06X, back side wirings 01x to 06x, and a back side connector 222. The configuration of the back side member 22 is the same as the configuration of the front side member 21. Briefly, the base film 220 is made of PET and has a sheet shape. The cover film 221 is also made of PET and has a sheet shape. The base film 220 and the cover film 221 are laminated with the back side electrodes 01X to 06X and the back side wirings 01x to 06x interposed therebetween.

  A total of six back-side electrodes 01X to 06X are arranged between the base film 220 and the cover film 221. Each of the back side electrodes 01X to 06X has a strip shape. The back-side electrodes 01X to 06X each extend in the X direction (left-right direction). The back-side electrodes 01X to 06X are arranged in the Y direction (front-rear direction) so as to be substantially parallel to each other at a predetermined interval. Each of the back-side electrodes 01X to 06X includes a flexible conductive layer 23X and a wiring part 24X. The back side electrodes 01X to 06X have the flexible electrode structure of the present invention.

  The flexible conductive layer 23X has a strip shape. The configuration of the flexible conductive layer 23X is the same as the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y. The wiring portion 24X has a linear shape extending from the left end to the right end of the flexible conductive layer 23X. The wiring portion 24X is disposed at the center of the back surface (lower surface) of the flexible conductive layer 23X. The wiring portion 24X is arranged so that variation in electric resistance in the length direction (left-right direction) of the flexible conductive layer 23X is reduced. The configuration of the wiring part 24X is the same as the wiring part 24Y of the front side electrodes 01Y to 06Y.

  A total of six back-side wirings 01x to 06x are arranged between the base film 220 and the cover film 221. The back side wirings 01x to 06x each have a linear shape. The back connector 222 is disposed at the left rear corner of the back member 22. The back connector 222 is electrically connected to the calculation unit 3. The back side wirings 01x to 06x connect the left end portions of the back side electrodes 01X to 06X and the back side connector 222, respectively. The back side wirings 01x to 06x each have a flexible conductive layer 23x and a wiring part 24x.

  The flexible conductive layer 23x has a linear shape. The flexible conductive layer 23x is formed by including acrylic rubber and carbon black in the same manner as the flexible conductive layer 23X of the back-side electrodes 01X to 06X. That is, the flexible conductive layer 23X and the flexible conductive layer 23x are continuously formed. The wiring part 24x has a linear shape. The width of the wiring part 24x is slightly smaller than the width of the flexible conductive layer 23x. The wiring part 24x is formed by including a polyester resin and silver powder, similarly to the wiring part 24X of the back-side electrodes 01X to 06X. That is, the wiring part 24X and the wiring part 24x are continuously formed.

  In the sensor main body 2, the detection units A0101 to A0606 are arranged at portions (overlapping portions) where the front side electrodes 01Y to 06Y and the back side electrodes 01X to 06X intersect in the vertical direction. A total of 36 (= 6 × 6) detectors A0101 to A0606 are arranged. The detectors A0101 to A0606 are arranged at substantially equal intervals over substantially the entire surface of the dielectric layer 20. Each of the detection units A0101 to A0606 includes a part of the front side electrodes 01Y to 06Y, a part of the back side electrodes 01X to 06X, a part of the dielectric layer 20, and a part of the base films 210 and 220. Yes. A surface pressure distribution is detected in a rectangular region surrounding the detection units A0101 to A0606.

  The calculation unit 3 includes a power supply circuit 30, a CPU (Central Processing Unit) 31, a RAM (Random Access Memory) 32, a ROM (Read Only Memory) 33, and an output unit 34. The computing unit 3 is electrically connected to the front side connector 212 and the back side connector 222.

  The power supply circuit 30 applies a sinusoidal AC voltage to the detection units A0101 to A0606. The ROM 33 stores in advance a map indicating the correspondence between the capacitance and the surface pressure in the detection units A0101 to A0606. The RAM 32 temporarily stores impedance and phase input from the front connector 212 and the back connector 222. The CPU 31 calculates the capacitance of the detection units A0101 to A0606 based on the impedance and the phase stored in the RAM 32. Then, the surface pressure distribution in the sensor body 2 is calculated from the capacitance. The output unit 34 outputs the surface pressure distribution calculated by the CPU 31.

[Method of manufacturing capacitive sensor]
Next, a method for manufacturing the capacitive sensor 1 of the present embodiment will be described. The manufacturing method of the capacitive sensor 1 of the present embodiment includes a front side member manufacturing step, a back side member manufacturing step, and a stacking step.

  In the front side member manufacturing step, the front side member 21 is manufactured. First, the carbon paste for forming the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23y of the front side wirings 01y to 06y is prepared. Moreover, a silver paste for forming the wiring part 24Y of the front side electrodes 01Y to 06Y and the wiring part 24y of the front side wirings 01y to 06y is prepared. Next, the prepared carbon paste is printed on the upper surface of the base film 210 using a screen printer. And a coating film is hardened by heating and flexible conductive layers 23Y and 23y are formed. Subsequently, the prepared silver paste is printed on the upper surfaces of the formed flexible conductive layers 23Y and 23y using a screen printer. And a coating film is hardened by heating and wiring part 24Y, 24y is formed. Next, the cover film 211 is covered from above the formed front side electrodes 01Y to 06Y and the front side wirings 01y to 06y. Finally, the front side members 21 are manufactured by connecting the front side wirings 01y to 06y and the front side connector 212.

  In the back side member production step, the back side member 22 is produced in the same manner as the front side member production step. First, the prepared carbon paste is screen-printed on the lower surface of the base film 220 (shown in the orientation in FIG. 2 and arranged upward at the time of printing), and the flexible conductive layer 23X of the back-side electrodes 01X to 06X and the back-side wiring 01x to A flexible conductive layer 23x of 06x is formed. Subsequently, the prepared silver paste is screen-printed on the lower surfaces of the formed flexible conductive layers 23X and 23x to form the wiring portions 24X of the back-side electrodes 01X to 06X and the wiring portions 24x of the back-side wirings 01x to 06x. Next, the cover film 221 is covered from below the formed back-side electrodes 01X to 06X and back-side wirings 01x to 06x. Finally, the back side wirings 01x to 06x and the back side connector 222 are connected to produce the back side member 22.

  In the stacking step, the front side member 21, the dielectric layer 20, and the back side member 22 are stacked. FIG. 4 shows a schematic diagram of this process. FIG. 4 corresponds to FIG. 2 (II-II cross section of FIG. 1). As shown in FIG. 4, in this process, the back side member 22, the dielectric layer 20, and the front side member 21 are laminated | stacked in an order from the bottom. At this time, the dielectric layer 20 is sandwiched between the base films 210 and 220 in the front and back members 21 and 22. The dielectric layer 20 is disposed so as to correspond to the formation region of the front side electrodes 01Y to 06Y and the back side electrodes 01X to 06X. And the electrostatic capacitance type sensor 1 of this embodiment is manufactured by bonding the peripheral part of the front side member 21 and the back side member 22 which oppose.

[Capacitive sensor movement]
Next, the movement of the capacitive sensor 1 of this embodiment will be described. First, before a load is applied to the capacitance type sensor 1 (initial state), the capacitance C is calculated for each of the detection units A0101 to A0606. That is, the capacitance C is calculated as if it were scanned from the detection unit A0101 to the detection unit A0606. The calculated capacitance C is stored in the RAM 32. Subsequently, after a load is applied to the capacitance type sensor 1, the capacitance C is calculated for each of the detection units A0101 to A0606. The calculated capacitance C is stored in the RAM 32.

  Then, the CPU 31 calculates the surface pressure applied to the sensor body 2 from the change amount ΔC of the capacitance C. Specifically, the ROM 33 stores a map indicating the correspondence between the capacitance C and the surface pressure in advance. Substituting the capacitance C into the map, the surface pressure of any of the detection units A0101 to A0606 is calculated. Then, the surface pressure is output from the output unit 34.

[Function and effect]
Next, the function and effect of the capacitive sensor 1 of the present embodiment will be described. According to the capacitive sensor 1 of the present embodiment, the front electrodes 01Y to 06Y each include the flexible conductive layer 23Y and the wiring part 24Y. The wiring portion 24Y extends in the length direction of the flexible conductive layer 23Y. For this reason, the distance to the wiring part 24Y is substantially equal from the front end to the rear end of the flexible conductive layer 23Y. Therefore, variation in electric resistance is small in the length direction of the flexible conductive layer 23Y. Moreover, the back side electrodes 01X to 06X also have the flexible conductive layer 23X and the wiring part 24X, and have the same effects as the front side electrodes 01Y to 06Y.

  Further, the wiring sections 24Y and 24X are arranged so as to overlap all the detection sections A0101 to A0606. For this reason, the variation in electrical resistance for each of the detection units A0101 to A0606 is small. Therefore, in the capacitance type sensor 1, a decrease in detection accuracy due to the electrical resistance distribution of the front-side electrodes 01Y to 06Y and the back-side electrodes 01X to 06X is small. That is, the measurement accuracy of the surface pressure distribution is high.

  The flexible conductive layers 23Y and 23X can be expanded and contracted. Therefore, it is difficult to regulate the deformation of the dielectric layer 20. On the other hand, the flexibility of the wiring portions 24Y and 24X is lower than that of the flexible conductive layers 23Y and 23X. For this reason, when the front-side electrodes 01Y to 06Y and the back-side electrodes 01X to 06X are extended following the deformation of the dielectric layer 20, there is a risk that a part of the wiring portions 24Y and 24X may crack and the conduction may be interrupted. There is. However, the wiring portions 24Y and 24X are disposed on the upper surface or the lower surface of the flexible conductive layers 23Y and 23X. Therefore, even if it is disconnected, conduction is ensured through the flexible conductive layers 23Y and 23X that are in contact with each other. Thus, the capacitive sensor 1 is excellent in durability. In the present embodiment, the areas of the wiring portions 24Y and 24X are smaller than the areas of the flexible conductive layers 23Y and 23X, respectively. Therefore, even if the wiring portions 24Y and 24X have poor flexibility, it is difficult to restrict the expansion and contraction of the flexible conductive layers 23Y and 23X. The wiring parts 24Y and 24X are formed using relatively expensive silver powder. However, since the areas of the wiring portions 24Y and 24X are small, the amount of silver powder used can be reduced as compared with the case where the wiring portions 24Y and 24X are arranged on the entire upper or lower surface of the flexible conductive layers 23Y and 23X. Thereby, manufacturing cost can be reduced.

  The capacitive sensor 1 of this embodiment is manufactured by laminating a front side member 21 and a back side member 22 with a dielectric layer 20 in between. For this reason, manufacture is easy. Further, the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23X of the back side electrodes 01X to 06X are not directly printed on the dielectric layer 20. For this reason, even if it is a material unsuitable for printing, such as a foam, it can be employ | adopted as the dielectric layer 20. FIG. Therefore, the degree of freedom in selecting the material of the dielectric layer 20 is high. The flexible conductive layers 23Y and 23X are formed from a carbon paste by a screen printing method. The wiring portions 24Y and 24X are formed from silver paste by a screen printing method. Therefore, even if the flexible conductive layers 23Y and 23X and the wiring portions 24Y and 24X are thin wires, thin films, and large areas, they can be easily formed.

<Second embodiment>
The main difference between the capacitive sensor of this embodiment and the capacitive sensor of the first embodiment is that the base films 210 and 220 are not arranged on the front member 21 and the back member 22. It is. Therefore, only the differences will be described here.

  FIG. 5 shows a cross-sectional view of the capacitive sensor of the present embodiment. The cross section shown in FIG. 5 corresponds to the II-II cross section of FIG. In FIG. 5, parts corresponding to those in FIG. As shown in FIGS. 1 and 5, the sensor main body 2 includes a dielectric layer 20, a front side member 21, and a back side member 22.

  The front side member 21 includes a cover film 211, front side electrodes 01Y to 06Y, front side wirings 01y to 06y, and a front side connector 212. The front side electrodes 01Y to 06Y are formed on the lower surface of the cover film 211. The front-side wirings 01y to 06y are formed on the lower surface of the cover film 211. A total of six front side electrodes 01Y to 06Y are arranged between the dielectric layer 20 and the cover film 211. Each of the front side electrodes 01Y to 06Y includes a flexible conductive layer 23Y and a wiring portion 24Y. The flexible conductive layer 23 </ b> Y is disposed so as to contact the upper surface of the dielectric layer 20.

  The back side member 22 includes a cover film 221, back side electrodes 01X to 06X, back side wirings 01x to 06x, and a back side connector 222. The back-side electrodes 01X to 06X are formed on the upper surface of the cover film 221. The back side wirings 01x to 06x are formed on the upper surface of the cover film 221. A total of six back-side electrodes 01X to 06X are arranged between the dielectric layer 20 and the cover film 221. Each of the back-side electrodes 01X to 06X includes a flexible conductive layer 23X and a wiring part 24X. The flexible conductive layer 23 </ b> X is disposed so as to contact the lower surface of the dielectric layer 20.

  The capacitive sensor of this embodiment is manufactured as follows. First, in the front side member manufacturing step, the silver paste is screen-printed on the lower surface of the cover film 211 (indicated by the orientation in FIG. 5 and arranged upward at the time of printing). And a coating film is hardened by heating and the wiring part 24Y of the front side electrodes 01Y-06Y and the wiring part 24y of the front side wirings 01y-06y are formed. Subsequently, the carbon paste is screen-printed on the lower surface of the cover film 211 so as to cover the wiring portions 24Y and 24y. Then, the coating film is cured by heating to form the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23y of the front side wirings 01y to 06y. Then, the front side wirings 01y to 06y and the front side connector 212 are connected to produce the front side member 21.

  Next, a silver paste is screen-printed on the upper surface of the cover film 221 in the back side member manufacturing step. Then, the coating film is cured by heating to form the wiring portion 24X of the back side electrodes 01X to 06X and the wiring portion 24x of the back side wirings 01x to 06x. Subsequently, the carbon paste is screen-printed on the upper surface of the cover film 221 so as to cover the wiring portions 24X and 24x. Then, the coating film is cured by heating to form the flexible conductive layer 23X of the back side electrodes 01X to 06X and the flexible conductive layer 23x of the back side wirings 01x to 06x. Then, the back side wirings 01x to 06x and the back side connector 222 are connected to produce the back side member 22.

  Next, in the stacking step, the back side member 22, the dielectric layer 20, and the front side member 21 are stacked in order from the bottom. At this time, the dielectric layer 20 is disposed so as to correspond to the formation region of the front-side electrodes 01Y to 06Y and the back-side electrodes 01X to 06X. That is, the dielectric layer 20 is sandwiched between the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23X of the back side electrodes 01X to 06X. And the electrostatic capacitance type sensor of this embodiment is manufactured by bonding the peripheral part of the front side member 21 and the back side member 22 which oppose.

  The capacitive sensor of the present embodiment has the same operational effects as the capacitive sensor of the first embodiment with respect to the parts having the same configuration. Further, according to the capacitive sensor of the present embodiment, the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23X of the back side electrodes 01X to 06X are directly disposed on the upper surface or the lower surface of the dielectric layer 20. ing. For this reason, the front side electrodes 01Y to 06Y and the back side electrodes 01X to 06X easily follow the deformation of the dielectric layer 20. In other words, the deformation of the dielectric layer 20 is not easily regulated. Moreover, since the base films 210 and 220 are not used, the number of parts can be reduced.

<Third embodiment>
The difference between the capacitive sensor of the present embodiment and the capacitive sensor of the first embodiment is that the front side member 21 and the back side member 22 are not disposed with the dielectric layer 20 in between, but the dielectric layer. The front-side electrodes 01Y to 06Y, the front-side wirings 01y to 06y, the back-side electrodes 01X to 06X, and the back-side wirings 01x to 06x are directly formed on the upper surface and the lower surface of 20, respectively. Therefore, only the differences will be described here.

  FIG. 6 shows a cross-sectional view of the capacitive sensor of this embodiment. The cross section shown in FIG. 6 corresponds to the II-II cross section of FIG. In FIG. 6, the parts corresponding to those in FIG. As shown in FIGS. 1 and 6, the sensor body 2 includes a dielectric layer 20, front side electrodes 01Y to 06Y, front side wirings 01y to 06y, a front side connector 212, back side electrodes 01X to 06X, and a back side wiring. 01x to 06x, and a back side connector 222.

  The dielectric layer 20 is made of silicone rubber and has a sheet shape. A total of six front side electrodes 01Y to 06Y are arranged on the upper surface of the dielectric layer 20. Similarly, a total of six front side wirings 01y to 06y are arranged on the upper surface of the dielectric layer 20. Each of the front side electrodes 01Y to 06Y includes a flexible conductive layer 23Y and a wiring portion 24Y. The flexible conductive layer 23 </ b> Y is formed on the upper surface of the dielectric layer 20.

  A total of six back-side electrodes 01X to 06X are arranged on the lower surface of the dielectric layer 20. Similarly, a total of six back side wirings 01x to 06x are arranged on the lower surface of the dielectric layer 20. Each of the back-side electrodes 01X to 06X includes a flexible conductive layer 23X and a wiring part 24X. The flexible conductive layer 23 </ b> X is formed on the lower surface of the dielectric layer 20.

  The capacitive sensor of this embodiment is manufactured as follows. First, a carbon paste is screen printed on the upper surface of the dielectric layer 20. Then, the coating film is cured by heating to form the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23y of the front side wirings 01y to 06y. Subsequently, a silver paste is screen-printed on the upper surfaces of the formed flexible conductive layers 23Y and 23y. And a coating film is hardened by heating and the wiring part 24Y of the front side electrodes 01Y-06Y and the wiring part 24y of the front side wirings 01y-06y are formed. Thereafter, the front side wirings 01y to 06y and the front side connector 212 are connected.

  Next, the carbon paste is screen-printed on the lower surface of the dielectric layer 20 (indicated by the orientation in FIG. 6 and arranged upward during printing). Then, the coating film is cured by heating to form the flexible conductive layer 23X of the back side electrodes 01X to 06X and the flexible conductive layer 23x of the back side wirings 01x to 06x. Subsequently, a silver paste is screen-printed on the lower surfaces of the formed flexible conductive layers 23X and 23x. Then, the coating film is cured by heating to form the wiring portion 24X of the back side electrodes 01X to 06X and the wiring portion 24x of the back side wirings 01x to 06x. Thereafter, the back side wirings 01x to 06x and the back side connector 222 are connected. In this manner, the capacitive sensor of this embodiment is manufactured.

  The capacitive sensor of the present embodiment has the same operational effects as the capacitive sensor of the first embodiment with respect to the parts having the same configuration. Further, according to the capacitive sensor of the present embodiment, the flexible conductive layer 23Y of the front side electrodes 01Y to 06Y and the flexible conductive layer 23X of the back side electrodes 01X to 06X are directly formed on the upper surface or the lower surface of the dielectric layer 20. ing. Therefore, it is easy to position the front side electrodes 01Y to 06Y and the back side electrodes 01X to 06X. Therefore, the detection units A0101 to A0606 can be accurately arranged at desired positions. Further, the front-side electrodes 01Y to 06Y and the back-side electrodes 01X to 06X easily follow the deformation of the dielectric layer 20. In other words, the deformation of the dielectric layer 20 is not easily regulated. Moreover, since the base films 210 and 220 and the cover films 211 and 221 are not used, the number of parts can be reduced.

<Fourth to seventh embodiments>
The difference between the capacitive sensor of the fourth to seventh embodiments and the capacitive sensor of the first embodiment is that the wiring portions 24Y and 24X in the front side electrodes 01Y to 06Y and the back side electrodes 01X to 06X are different. Arrangement form. Therefore, only the differences will be described here.

  FIG. 7 shows a top view of the front-side electrode 01Y in the capacitive sensor of the fourth embodiment. As shown in FIG. 7, the wiring part 24Y includes a trunk part 240Y and six branch parts 241Y. The trunk portion 240Y has a linear shape extending backward from the front end of the flexible conductive layer 23Y. The trunk portion 240Y is disposed on the upper left side of the flexible conductive layer 23Y. Each of the six branch portions 241Y is arranged to branch rightward from the trunk portion 240Y. The six branch portions 241Y are arranged so as to be substantially parallel to each other at regular intervals in the front-rear direction. According to this embodiment, the variation in electrical resistance in the length direction and width direction of the flexible conductive layer 23Y is reduced.

  FIG. 8 shows a top view of the front-side electrode 01Y in the capacitive sensor of the fifth embodiment. As shown in FIG. 8, the wiring part 24Y includes a trunk part 240Y and six branch parts 241Y. The trunk portion 240Y has a linear shape extending backward from the front end of the flexible conductive layer 23Y. The trunk portion 240Y is disposed at the center of the upper surface of the flexible conductive layer 23Y. Each of the six branch portions 241Y is branched from the trunk portion 240Y to the left and right. The six branch portions 241Y are arranged so as to be substantially parallel to each other at regular intervals in the front-rear direction. According to this embodiment, the variation in electrical resistance in the length direction and width direction of the flexible conductive layer 23Y is reduced.

  FIG. 9 shows a top view of the front electrode 01Y in the capacitive sensor of the sixth embodiment. As shown in FIG. 9, the wiring part 24Y has a rectangular wave shape that advances backward from the front end of the flexible conductive layer 23Y. According to this embodiment, the variation in electrical resistance in the length direction and width direction of the flexible conductive layer 23Y is reduced.

  FIG. 10 shows a top view of the front-side electrode 01Y in the capacitive sensor of the seventh embodiment. As shown in FIG. 10, the wiring part 24Y has a frame shape. The wiring portion 24Y is disposed along the peripheral edge portion of the flexible conductive layer 23Y. According to this embodiment, the variation in electrical resistance in the length direction and width direction of the flexible conductive layer 23Y is reduced.

<Others>
The embodiment of the flexible electrode structure and the transducer of the present invention has been described above. However, the embodiment is not limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, in the above embodiment, the flexible conductive layers of the front side electrode and the back side electrode are formed from a carbon paste containing acrylic rubber and carbon black. However, the type of elastomer constituting the flexible conductive layer is not particularly limited. In addition to acrylic rubber, for example, silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber Etc. are suitable.

  Also, the type of conductive carbon powder is not particularly limited. As the conductive carbon powder, graphite powder or the like can be used in addition to carbon black. Examples of carbon black include ketjen black, acetylene black, thermal black, furnace black, lamp black, and channel black. Of these, ketjen black and acetylene black are preferred from the viewpoint of high conductivity. Examples of the graphite powder include natural graphite powder such as flake graphite, lump graphite, and earth graphite, and artificial graphite powder. Of these, flake graphite powder is preferred from the viewpoint of high conductivity.

  The elongation percentage of the flexible conductive layer is desirably 150% or more. From the viewpoint of securing the stretchability of the flexible conductive layer, it is desirable that a relatively small amount of conductive carbon powder be blended to develop conductivity. For example, the blending amount of the conductive carbon powder is desirably 75 vol% or less when the volume of the flexible conductive layer is 100 vol%. It is more preferable that it is 50 vol% or less.

  The flexible conductive layer may contain various additives in addition to the elastomer and the conductive carbon powder. Examples of additives include cross-linking agents, vulcanization accelerators, vulcanization aids, curing agents, anti-aging agents, plasticizers, softeners, colorants, dispersants, coupling agents, leveling agents, antifoaming agents, and the like. Is mentioned.

In the said embodiment, the wiring part of a front side electrode and a back side electrode was formed from the silver paste containing a polyester resin and silver powder. However, the wiring portion only needs to have a smaller volume resistivity than the flexible conductive layer, and the material is not particularly limited. For example, the wiring portion may be formed from a metal wire, a metal foil, or the like. Moreover, you may form a wiring part from the electrically conductive paste which mix | blended the metal powder and the conductive carbon powder with the binder like the said embodiment. As the metal, silver, gold, copper, nickel, rhodium, palladium, chromium, titanium, platinum, iron, and alloys thereof are preferable. Moreover, the kind of binder is not specifically limited. The same or different elastomer as the flexible conductive layer may be used, or a resin may be used. As the resin, in addition to polyester resin, epoxy resin, modified polyester resin (urethane modified polyester resin, epoxy modified polyester resin, acrylic modified polyester resin, etc.), polyether urethane resin, polycarbonate urethane resin, vinyl chloride-vinyl acetate copolymer , Phenol resin, acrylic resin, polyamideimide resin, polyimide resin, polyamide resin, nitrocellulose, and modified celluloses (cellulose / acetate / butylate (CAB), cellulose / acetate / propionate (CAP), etc.). The volume resistivity of the wiring part is desirably 1 × 10 ⁻⁵ Ω · cm or less.

  Moreover, the arrangement | positioning form of a wiring part is not specifically limited. The wiring portion may be arranged so that variation in electric resistance in the surface direction of the flexible conductive layer is smaller than when the flexible conductive layer is used alone. For example, you may arrange | position so that the whole surface of a flexible conductive layer may be coat | covered. However, from the viewpoint of reducing the manufacturing cost and making it difficult to restrict the expansion and contraction of the flexible conductive layer, the area of the wiring portion is desirably smaller than the area of the flexible conductive layer. As an arrangement form of the wiring portion, a curved shape, a meandering shape, a zigzag shape, or the like may be used in addition to the above embodiment. Moreover, in the capacitive sensor of the above embodiment, different arrangement forms may be adopted for the front side electrode and the back side electrode.

  In the above embodiment, the front-side wiring and the back-side wiring constituting the capacitance type sensor are also composed of the flexible conductive layer and the wiring portion in the same manner as the front-side electrode and the back-side electrode. However, the configuration of the front side wiring and the back side wiring is not particularly limited. For example, you may comprise only a wiring part. Moreover, a well-known metal wiring etc. may be sufficient.

  As the dielectric layer constituting the transducer, an elastomer or a resin may be used. Elastomers include rubber and thermoplastic elastomers. For example, from the viewpoint of increasing the capacitance, one having a high relative dielectric constant is desirable. Specifically, it is desirable that the relative dielectric constant at room temperature is 3 or more, and further 5 or more. For example, an elastomer having a polar functional group such as an ester group, a carboxyl group, a hydroxyl group, a halogen group, an amide group, a sulfone group, a urethane group, or a nitrile group, or an elastomer added with a polar low molecular weight compound having these polar functional groups Is preferred. The elastomer may or may not be cross-linked. In addition, the detection sensitivity and detection range of the capacitive sensor can be adjusted by adjusting the Young's modulus of the elastomer or resin used for the dielectric layer. For example, when detecting a small load, a foam having a small Young's modulus may be used.

  Examples of suitable elastomers include silicone rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and urethane rubber. Suitable resins include polyethylene, polypropylene, polyurethane, polystyrene (including cross-linked expanded polystyrene), polyvinyl chloride, vinylidene chloride copolymer, ethylene-vinyl acetate copolymer, and the like. As polypropylene, polypropylene (modified PP) modified with polyethylene (PE) and / or ethylene propylene rubber (EPR) may be used. Moreover, you may use the polymer alloy or polymer blend containing 2 or more types of these resin.

  In other than the third embodiment, the capacitive sensor was configured by sandwiching the dielectric layer between the front side substrate and the back side substrate. Here, the materials of the base film and the cover film in the front side substrate and the back side substrate are not particularly limited. In addition to PET in the above embodiment, a flexible resin film made of polyimide, polyethylene, polyethylene naphthalate (PEN), or the like can be used. In the third embodiment, a cover film may be disposed so as to cover the electrode.

  In the said embodiment, the flexible electrode structure of this invention was embodied as a strip | belt-shaped electrode. However, the shape of the electrode having the flexible electrode structure of the present invention (the shape of the flexible conductive layer) is not particularly limited. In the present specification, the “strip shape” means an elongated shape. Therefore, the width is not necessarily constant in the length direction. For example, even if the width of the predetermined portion in the length direction is wide, the width of the predetermined portion may be narrow on the contrary. Further, the side portion may be linear or curved.

  For example, the shape of the electrode may be a circle, an ellipse, or the like in addition to a rectangle. FIG. 11 shows a top view of an electrode example having the flexible electrode structure of the present invention. The electrode 25 has a flexible conductive layer 250 and a wiring portion 251. The flexible conductive layer 250 has a circular shape. The wiring portions 251 are arranged radially from the center of the surface of the flexible conductive layer 250. In addition to this embodiment, the wiring portion may be arranged in a spiral shape. Circular and elliptical electrodes are suitable for use in, for example, speakers and actuators.

  The formation method of the electrode which has a flexible electrode structure of this invention is not specifically limited. For example, a flexible conductive layer may be formed by pressurizing and heating a composition containing a polymer for an elastomer and conductive carbon powder by molding or extrusion molding. Alternatively, a flexible conductive layer may be formed by applying and curing a conductive paste containing a polymer for elastomer and conductive carbon powder. And a metal wire etc. may be arrange | positioned on the surface of a flexible conductive layer, and a wiring part should just be formed. Alternatively, the wiring portion may be formed from a conductive paste. In order to apply the conductive paste, various known methods may be employed. For example, in addition to printing methods such as inkjet printing, flexographic printing, gravure printing, screen printing, pad printing, and lithography, dipping, spraying, bar coating, and the like can be given.

  A transducer is a device that converts one type of energy into another type of energy. The transducer includes an actuator, a sensor, a power generation element, or the like that converts mechanical energy and electric energy, or a speaker, a microphone, or the like that converts acoustic energy and electric energy. Therefore, the transducer of the present invention is not limited to the capacitive sensor of the above embodiment.

1: Capacitive sensor (transducer)
2: Sensor body 20: Dielectric layer 21: Front side member 22: Back side member 23X, 23Y, 23x, 23y: Flexible conductive layer 24X, 24Y, 24x, 24y: Wiring part 25: Electrode 210, 220: Base film 211, 221: Cover film 212: Front side connector 222: Back side connector 240Y: Trunk part 241Y: Branch part 250: Flexible conductive layer 251: Wiring part 3: Calculation part 30: Power supply circuit 31: CPU 32: RAM 33: ROM
34: Output unit 01X to 06X: Back side electrode 01Y to 06Y: Front side electrode 01x to 06x: Back side wiring 01y to 06y: Front side wiring A0101 to A0606: Detection unit

Claims (6)

A flexible conductive layer comprising an elastomer and conductive carbon powder;
A wiring portion that is disposed on the surface of the flexible conductive layer and has a smaller volume resistivity than the flexible conductive layer;
With
The area of the wiring portion is smaller than the area of the flexible conductive layer,
The flexible electrode structure, wherein the wiring portion is arranged so that variation in electric resistance in a surface direction of the flexible conductive layer is reduced. The flexible conductive layer has a strip shape,
The flexible electrode structure according to claim 1, wherein the wiring portion extends at least in a longitudinal direction of the flexible conductive layer. The flexible electrode structure according to claim 1, wherein the wiring part includes a binder and a metal powder. The flexible electrode structure according to any one of claims 1 to 3 , wherein the flexible conductive layer and the wiring portion are both formed by a printing method. A dielectric layer made of elastomer or resin, and a plurality of electrodes disposed through the dielectric layer,
The plurality of electrodes are transducers having the flexible electrode structure according to any one of claims 1 to 4 . The plurality of electrodes comprises a plurality of front side electrodes disposed on the front side of the dielectric layer, and a plurality of back side electrodes disposed on the back side of the dielectric layer,
A plurality of detection parts formed by the flexible conductive layer of the front electrode and the flexible conductive layer of the back electrode facing each other through the dielectric layer;
In each of the front side electrode and the back side electrode, the wiring part is disposed so as to overlap at least the detection part,
The transducer according to claim 5 , wherein the transducer is a capacitance type sensor capable of detecting a surface pressure distribution from a change in capacitance of the detection unit.

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