JP4565359B2 - Capacitance type surface pressure distribution sensor - Google Patents

Description

  The present invention relates to a capacitance-type surface pressure distribution sensor capable of detecting a concavo-convex shape of a measurement object as a surface pressure distribution from a change in capacitance.

  For example, Patent Document 1 discloses a sensor sheet in which a large number of sensor cells are distributed. The sensor cell includes a capacitor element electrode and a displacement electrode. A gap is defined between the capacitive element electrode and the displacement electrode. In other words, an air layer is interposed between the capacitive element electrode and the displacement electrode.

When a load is applied from the measurement object to the sensor cell, the thickness of the air layer changes. When the thickness of the air layer changes, the capacitance between the capacitive element electrode and the displacement electrode changes. Based on the change in the capacitance, the sensor sheet detects the uneven shape of the measurement object as a surface pressure distribution.
JP 2004-117042 A

Incidentally, the capacitance of the capacitance type sensor cell is derived from the following equation (1).

In the formula (1), C is a capacitance, ε ₀ is a vacuum dielectric constant, ε _r is a relative dielectric constant, s is an area of the electrode, and d is a distance between the pair of electrodes. As is clear from the equation (1), the capacitance C increases as the relative dielectric constant ε _r increases. For this reason, the electrostatic capacitance output from the sensor cell also increases. That is, the change in capacitance after the load is applied from the measurement object to the sensor cell with respect to that before the load is applied from the measurement object to the sensor cell also increases.

However, in the case of the sensor cell described in the above document, an air layer is interposed between the capacitive element electrode and the displacement electrode. That is, an air layer is disposed as a dielectric layer. For this reason, compared with the case where organic substance is arrange | positioned as a dielectric layer, the sensor cell of the said literature description has a small dielectric constant (epsilon) _r . Therefore, the change in the capacitance output from the sensor cell is small.

  Further, in the case of the sensor sheet described in the above document, one sensor cell is arranged for each part where the surface pressure is to be detected. For this reason, the number of sensor cells arranged, that is, the number of electrodes arranged is large. In addition, since the number of electrodes arranged is large, the number of wires for detecting the capacitance is also large.

  The capacitive surface pressure distribution sensor of the present invention has been completed in view of the above problems. Therefore, an object of the present invention is to provide a capacitance-type surface pressure distribution sensor with a large change in capacitance and a small number of electrodes.

  (1) In order to solve the above-described problem, the capacitive surface pressure distribution sensor of the present invention is provided with an elastomeric dielectric layer and at least one dielectric layer on the front side of the dielectric layer, and the elastomer and the elastomer are filled. A belt-shaped front electrode having a front-side connection portion, at least one disposed on the back side of the dielectric layer, an elastomer, and a conductive filler filled in the elastomer. A plurality of detection parts formed by crossing the front-side electrode and the back-side electrode when viewed from the front-back direction, and the front-side connection part. An elastomer and conductive particles filled in the elastomer, and connected to the front-side wiring having a lower electrical resistance than the front-side electrode and to the back-side connecting portion; And a conductive particle filled with the elastomer, and a back side wiring having an electric resistance smaller than that of the back side electrode. An electrical resistance that is electrically connected to the backside wiring and that is detected from the frontside wiring and the backside wiring, according to a distance from the front side connection part to the detection part in the front side electrode, and the back side in the back side electrode Calculation to separate the electrical resistance depending on the distance from the connection part to the detection part, extract the capacitance of the detection part, and calculate the surface pressure distribution in the sensor body from the capacitance of the detection part And a section (corresponding to claim 1).

  The capacitance-type surface pressure distribution sensor of the present invention includes a sensor main body and a calculation unit. The sensor main body includes a dielectric layer, a front side electrode, a back side electrode, a detection unit, a front side wiring, and a back side wiring. The dielectric layer is made of an elastomer. For this reason, compared with the case where a dielectric layer is air, an electrostatic capacitance becomes large. That is, the change in the capacitance after the load is applied from the measurement object to the sensor body (when the load is applied) with respect to before the load is applied from the measurement object to the sensor body is increased.

  Moreover, both the front side electrode and the back side electrode are strip-shaped. And the detection part is arrange | positioned using the cross | intersection part of a front side electrode and a back side electrode. For this reason, the number of electrodes is reduced. In addition, the number of wires for detecting the capacitance from the detection unit is reduced.

  Moreover, the front side electrode and the back side electrode are formed including an elastomer and a conductive filler filled in the elastomer. For this reason, when a surface pressure is applied from the measurement object, the front side electrode and the back side electrode can expand and contract together with the dielectric layer in accordance with the surface pressure. Therefore, there is little possibility that the expansion or contraction of the dielectric layer is restricted by the front side electrode or the back side electrode.

  Moreover, the front side wiring and the back side wiring are formed including an elastomer and conductive particles filled in the elastomer. For this reason, when a load is applied from the measurement object, the front-side wiring and the back-side wiring can expand and contract according to the load. Therefore, there is little possibility that the expansion or contraction of the dielectric layer is restricted by the front side wiring or the back side wiring.

Incidentally, the electrical resistance of the object is derived from the following equation (2).

  In formula (2), r is electrical resistance, ρ is resistivity, L is length, and S is a cross-sectional area. As apparent from the above formula (2), the longer the length L of the object, the greater the electrical resistance r. For this reason, electrical resistance becomes large, so that the distance from the front side connection part in a front side electrode to a detection part is long. Similarly, the longer the distance from the back side connection part to the detection part in the back side electrode, the greater the electrical resistance. That is, the electrical resistance due to the distance may be different in each of the plurality of detection units. Therefore, when the surface pressure distribution is calculated using the impedance detected from the front side wiring and the back side wiring as they are, the measurement accuracy of the surface pressure distribution is lowered due to the influence of the electric resistance.

  In this regard, according to the capacitance-type surface pressure distribution sensor of the present invention, from the impedance detected from the front side wiring and the back side wiring, the electrical resistance depending on the distance from the front side connection part to the detection part in the front side electrode, and the back side in the back side electrode The electric resistance according to the distance from the connection part to the detection part is separated. That is, the capacitance of the detection unit is extracted from the detected impedance. For this reason, the measurement accuracy of the surface pressure distribution is high.

  (1-1) Preferably, in the configuration of the above (1), the elastomer that is a material of the dielectric layer is silicone rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, It is better to set it as the structure containing 1 or more types chosen from chlorinated polyethylene and urethane rubber. According to this configuration, the dielectric constant of the dielectric layer is increased. For this reason, an electrostatic capacitance can be enlarged.

  (1-2) Preferably, in the configuration of (1) above, at least one of the elastomer that is the material of the front electrode and the elastomer that is the material of the back electrode is made of silicone rubber or ethylene-propylene copolymer. It is better to have one or more types selected from rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and urethane rubber. Good. According to this configuration, the elasticity of at least one of the front side electrode and the back side electrode is increased. For this reason, at least one of the front-side electrode and the back-side electrode and the dielectric layer are easily expanded and contracted integrally.

  (1-3) Preferably, in the configuration of (1) above, the conductive filler contained in the front side electrode and the back side electrode is preferably a nonmetallic conductive filler. According to this structure, compared with the case where a front side electrode and a back side electrode contain a metal-type conductive filler, the electrical resistance of a front side electrode and a back side electrode becomes large. That is, the electrical resistance due to the distance from the front side connection part to the detection part in the front side electrode and the electrical resistance due to the distance from the back side connection part to the detection part in the back side electrode increase. These electrical resistances are separated from the detected impedance. For this reason, according to this structure, although the electrical resistance of a front side electrode and a back side electrode is large, the measurement precision of surface pressure distribution is high.

  (1-4) Preferably, in the configuration of (1-3) above, the nonmetallic conductive filler is preferably a carbon conductive filler. According to this configuration, the measurement accuracy of the surface pressure distribution is high even though the electrical resistance of the front electrode and the back electrode is large.

  (2) Preferably, in the configuration of (1), the calculation unit is configured to calculate a total load applied to the sensor body by integrating the capacitances of the plurality of detection units. Good (corresponding to claim 2). According to this configuration, the total load applied to the sensor body can be calculated from the capacitance of each detection unit. For this reason, for example, the weight of the measurement object can be detected.

  (3) Preferably, in the configuration of the above (1) or (2), the front side electrodes are arranged in a plurality of rows, the back side electrodes are arranged in a plurality of rows, and a plurality of the front sides are arranged. The electrode and the plurality of backside electrodes are preferably arranged so as to be substantially orthogonal when viewed from the front and back directions (corresponding to claim 3).

  According to this configuration, it is easy to disperse a plurality of detection units over the entire surface of the sensor body. For this reason, the area of the part which can detect surface pressure which occupies the whole sensor main body can be enlarged. In addition, it is possible to suppress variations in the arrangement of the detection units on the entire surface of the sensor body.

  (4) Preferably, in any one of the configurations (1) to (3), the front side electrode and the front side wiring are printed on a surface of the dielectric layer, and the back side electrode and the back side wiring are It is better to have a structure printed on the back surface of the dielectric layer (corresponding to claim 4).

  That is, in this configuration, the sensor body is manufactured by printing the front side electrode, the front side wiring, the back side electrode, and the back side wiring on the dielectric layer. According to this configuration, the components essential for the surface pressure measurement such as the dielectric layer, the front side electrode, the front side wiring, the back side electrode, and the back side wiring can be integrated relatively easily. For this reason, the productivity of the sensor body, and hence the capacitive surface pressure distribution sensor, is high.

  Moreover, the front side electrode and the back side electrode are directly printed on the dielectric layer. For this reason, positioning with a front side electrode and a back side electrode is easy. Therefore, the detection unit can be accurately arranged at a desired position.

  (5) Preferably, in the configuration according to any one of (1) to (4), the sensor main body is further printed by directly or indirectly covering the front side electrode and the front side wiring. A front-side insulation coating layer that insulates the electrode and the front-side wiring from the outside, and a back-side insulation that covers the back-side electrode and the back-side wiring, directly or indirectly, and that insulates the back-side electrode and the back-side wiring from the outside. It is better to have a structure having a coating layer (corresponding to claim 5).

  According to this structure, it can suppress that a front side electrode and front side wiring, and the member outside an electrostatic capacitance type surface pressure distribution sensor conduct | electrically_connect. In addition, it is possible to suppress conduction between the back-side electrode and the back-side wiring and a member outside the capacitive surface pressure distribution sensor.

  (6) Preferably, in any one of the configurations (1) to (3), the sensor main body further includes a cylindrical cylindrical insulating member that insulates the inside and outside of the cylinder, and the dielectric layer includes The front side electrode and the front side wiring are housed in the insulating cylinder member, and are printed on the inner surface of the insulating cylinder member and facing the surface of the dielectric layer. It is preferable that the back-side wiring is printed on the inner surface of the insulating cylinder member and on the portion facing the back surface of the dielectric layer (corresponding to claim 6).

  According to this configuration, the components essential for the surface pressure measurement, such as the dielectric layer, the front side electrode, the front side wiring, the back side electrode, and the back side wiring, are accommodated inside the insulating cylinder member. For this reason, it can suppress that these members and the member of the outer side of an insulating cylinder member conduct | electrically_connect.

  (7) Preferably, in any one of the configurations (1) to (6), the surface resistance between the longitudinal ends of at least one of the front side electrode and the back side electrode is 100 kΩ or less. It is better (corresponding to claim 7). Here, the surface resistance between both ends in the longitudinal direction is set to 100 kΩ or less because when 100 kΩ is exceeded, the current that flows when the AC voltage is applied becomes small, and the impedance measurement accuracy decreases, resulting in a capacitance measurement error. This is to expand.

  (7-1) Preferably, in any one of the configurations (1) to (6), at least one of the front electrode and the back electrode includes the elastomer and the conductive filler. In the percolation curve representing the relationship between the blending amount of the conductive filler and the electrical resistance of the elastomer composition, the electrical conductivity at the first inflection point where the electrical resistance decreases and the insulator-conductor transition occurs. It is better to have a configuration in which the filler content (critical volume fraction: φc) is 25 vol% or less.

  Generally, when an electrically conductive filler is mixed with an insulating elastomer to form an elastomer composition, the electrical resistance of the elastomer composition varies depending on the blending amount of the conductive filler. In FIG. 1, the relationship between the compounding quantity of an electroconductive filler and an electrical resistance in an elastomer composition is shown typically.

  As shown in FIG. 1, when the conductive filler 102 is mixed with the elastomer 101, the electrical resistance of the elastomer composition is almost the same as the electrical resistance of the elastomer 101 at the beginning. However, when the blending amount of the conductive filler 102 reaches a certain volume fraction, the electric resistance rapidly decreases and an insulator-conductor transition occurs (first inflection point). A blending amount of the conductive filler 102 at the first inflection point is referred to as a critical volume fraction (φc). Further, when the conductive filler 102 is further mixed, from a certain volume fraction, the change in electrical resistance is reduced and the change in electrical resistance is saturated (second inflection point). The blending amount of the conductive filler 102 at the second inflection point is referred to as a saturated volume fraction (φs). Such a change in electrical resistance is called a percolation curve and is considered to be due to the formation of a conductive path P1 by the conductive filler 102 in the elastomer 101.

  For example, when primary particles of the conductive filler aggregate and secondary particles are formed, a conductive path is easily formed by a three-dimensional network structure. In such a case, the critical volume fraction (φc) of the elastomer composition is relatively small, such as about 20 vol%. In other words, when the critical volume fraction (φc) is small, the conductive filler tends to form a secondary aggregate having a structure property. For this reason, even if the compounding quantity of a conductive filler is comparatively small, a highly conductive elastomer composition can be obtained.

  According to this configuration, at least one of the front electrode and the back electrode is made of an elastomer composition having a critical volume fraction (φc) of 25 vol% or less. Since the critical volume fraction (φc) is relatively small, the conductive filler tends to form aggregates. Therefore, an electrode having good conductivity can be obtained with a relatively small amount of the conductive filler. The “elastomer composition” in the present specification includes a mixture of an elastomer, a conductive filler, and other additives in addition to a mixture of an elastomer and a conductive filler.

  (8) Preferably, in any one of the constitutions (1) to (7), the conductive filler is selected from conductive carbon black, carbon nanotubes, carbon nanotube derivatives, graphite, and conductive carbon fibers. It is better to have a configuration composed of more than one type (corresponding to claim 8). Among these, conductive carbon black, graphite, and conductive carbon fiber have good conductivity and are relatively inexpensive. For this reason, according to this structure, the manufacturing cost of an electrostatic capacitance type surface pressure distribution sensor can be reduced.

  According to the present invention, it is possible to provide a capacitance-type surface pressure distribution sensor having a large capacitance change and a small number of electrodes.

  Next, an embodiment of the capacitive surface pressure distribution sensor of the present invention will be described.

<First embodiment>
[Configuration of Capacitive Surface Pressure Distribution Sensor]
First, the configuration of the capacitive surface pressure distribution sensor of this embodiment will be described. FIG. 2 is a top transparent view of the capacitive surface pressure distribution sensor of this embodiment. In FIG. 2, the front side insulating coating layer and the back side insulating coating layer are omitted. Further, the back side electrode and the back side wiring are shown by thin lines. In addition, the detection unit is hatched. FIG. 3 shows a cross-sectional view in the III-III direction of FIG. In FIG. 3, the thickness of the sensor body in the vertical direction is highlighted. As shown in FIGS. 2 and 3, the capacitive surface pressure distribution 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, front side electrodes 01X to 16X, back side electrodes 01Y to 16Y, detection units A0101 to A1616, front side wirings 01x to 16x, back side wirings 01y to 16y, and a front side insulating coating layer 21. A back-side insulating coating layer 22, a front-side wiring connector 23, and a back-side wiring connector 24. It should be noted that in the sign “AOOΔΔ” of the detection unit, the upper two digits “OO” correspond to the front electrodes 01X to 16X. The last two digits “ΔΔ” correspond to the back-side electrodes 01Y to 16Y.

  The dielectric layer 20 is made of ether urethane rubber and has a sheet shape. The dielectric layer 20 has a hardness (type A durometer hardness: JIS K6253 (2006)) of 90 degrees. The dielectric layer 20 extends in the XY direction (front / rear / left / right direction).

  A total of 16 front side electrodes 01 </ b> X to 16 </ b> X are arranged on the upper surface of the dielectric layer 20. The front-side electrodes 01X to 16X are each formed including acrylic rubber and conductive carbon black. The front side electrodes 01X to 16X each have a strip shape. The front side electrodes 01X to 16X each extend in the X direction (left-right direction). The front-side electrodes 01X to 16X are arranged in the Y direction (front-rear direction) so as to be substantially parallel to each other at a predetermined interval. Front side connection portions 01X1 to 16X1 are arranged at the left ends of the front side electrodes 01X to 16X, respectively.

  A total of 16 front side wirings 01x to 16x are arranged on the upper surface of the dielectric layer 20. The front side wirings 01x to 16x are each formed to include urethane rubber and silver powder. The front side wirings 01x to 16x each have a linear shape. The front wiring connector 23 is disposed at the left rear corner of the dielectric layer 20. The front side wirings 01x to 16x connect the front side connection portions 01X1 to 16X1 and the front side wiring connector 23, respectively.

  The front-side insulating coating layer 21 is disposed above the dielectric layer 20. The front-side insulating coating layer 21 is formed including acrylic rubber. The front-side insulating coating layer 21 has a sheet shape. The front-side insulating coating layer 21 covers the dielectric layer 20, the front-side electrodes 01X to 16X, and the front-side wirings 01x to 16x from above.

  A total of 16 back-side electrodes 01Y to 16Y are arranged on the lower surface of the dielectric layer 20. The back-side electrodes 01Y to 16Y are each formed including acrylic rubber and conductive carbon black. The back side electrodes 01Y to 16Y each have a strip shape. The back-side electrodes 01Y to 16Y each extend in the Y direction. The back-side electrodes 01Y to 16Y are arranged in the X direction so as to be substantially parallel to each other at a predetermined interval. Back side connection portions 01Y1 to 16Y1 are arranged at the front ends of the back side electrodes 01Y to 16Y, respectively.

  A total of 16 backside wirings 01y to 16y are arranged on the lower surface of the dielectric layer 20. The back side wirings 01y to 16y are each formed including urethane rubber and silver powder. The back side wirings 01y to 16y each have a linear shape. The back side wiring connector 24 is disposed at the left front corner of the dielectric layer 20. The back side wirings 01y to 16y connect the back side connection portions 01Y1 to 16Y1 and the back side wiring connector 24, respectively.

  The back side insulating coating layer 22 is disposed below the dielectric layer 20. The back side insulating coating layer 22 is formed including acrylic rubber. The back side insulating coating layer 22 has a sheet shape. The back side insulating coating layer 22 covers the dielectric layer 20, the back side electrodes 01Y to 16Y, and the back side wirings 01y to 16y from below.

  As shown by hatching in FIG. 2, the detection units A0101 to A1616 are arranged at portions (overlapping portions) where the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y intersect in the vertical direction. A total of 256 (= 16 × 16) detectors A0101 to A1616 are arranged. The detectors A0101 to A1616 are arranged at substantially equal intervals over substantially the entire surface of the sensor body 2. Each of the detection units A0101 to A1616 includes a part of the front side electrodes 01X to 16X, a part of the back side electrodes 01Y to 16Y, and a part of the dielectric layer 20.

  The arithmetic 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 a display 34. The computing unit 3 is electrically connected to the front-side wiring connector 23 and the back-side wiring connector 24.

  The power supply circuit 30 applies a sinusoidal AC voltage to the detection units A0101 to A1616. The ROM 33 stores in advance a map indicating the correspondence between the capacitance and the surface pressure in the detection units A0101 to A1616. The ROM 33 stores formulas (3) and (5) described later. The RAM 32 temporarily stores impedance and phase input from the front-side wiring connector 23 and the back-side wiring connector 24. As will be described later, the CPU 31 extracts capacitances of the detection units A0101 to A1616 using the equations (3) and (5) 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 display 34 displays the surface pressure distribution calculated by the CPU 31 on a screen (not shown) as, for example, a three-dimensional graph.

[Manufacturing Method of Capacitive Surface Pressure Distribution Sensor]
Next, a manufacturing method of the capacitive surface pressure distribution sensor 1 of the present embodiment will be described. The manufacturing method of the capacitance type surface pressure distribution sensor 1 of the present embodiment includes a paint preparation step, a front side electrode printing step, a front side wiring printing step, a front side insulating coating layer printing step, a back side electrode printing step, and a back side. A wiring printing process and a back side insulating coating layer printing process.

  In the paint preparation step, an electrode paint, a wiring paint, and a coating layer paint are prepared. The electrode paint is prepared by the following procedure. First, 100 parts by mass of a polymer (acrylic rubber, trade name: Nipol (registered trademark) AR51, manufactured by Nippon Zeon Co., Ltd.), a vulcanization aid (stearic acid, trade name: Lunac (registered trademark) S30, manufactured by Kao Corporation) 00 parts by mass, vulcanization accelerator (zinc dimethyldithiocarbamate, trade name: Noxeller (registered trademark) PZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 2.50 parts by mass, vulcanization accelerator (ferric dimethyldithiocarbamate, commodity Name: Noxeller TTFE (manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.50 part by mass is weighed and rubber is kneaded using a roll. Then, a rubber compound is prepared. Subsequently, the prepared rubber compound is immersed in 1500 parts by mass of an organic solvent (methyl ethyl ketone, Sankyo Chemical Co., Ltd.), the organic solvent is stirred, and a solution in which the rubber compound is uniformly dissolved in the organic solvent is obtained. Then, 22.86 parts by mass of conductive carbon black (Ketjen Black, trade name: EC300J, manufactured by Lion Corporation) is added to the solution. Then, a MEK (methyl ethyl ketone) solution having a solid content of about 7.8% by mass is obtained. Then, the MEK solution is milled to improve the dispersibility of the conductive carbon black in the MEK solution. Specifically, the MEK solution is put into a dyno mill rotating at 3200 rpm, and the MEK solution is circulated about 40 times. Thereafter, 686.7 parts by mass of a printing solvent (diethylene glycol monobutyl ether acetate, manufactured by Sankyo Chemical Co., Ltd.) is added to the milled MEK solution. Then, the MEK solution to which the printing solvent is added is transferred to a container having a wide mouth in order to widen the area in contact with the atmosphere. Then, the MEK solution is allowed to stand for about one day with occasional stirring to sufficiently evaporate MEK having a low boiling point. In this way, an electrode paint is prepared. The boiling point of the printing solvent is 200 ° C. or higher. For this reason, the volatilization of the printing solvent is negligible.

  The wiring paint is prepared by the following procedure. First, 333 parts by mass of polymer (polyurethane dissolved in MEK / toluene / isopropyl alcohol, trade name: NIPPOLAN (registered trademark) 5230, manufactured by Nippon Polyurethane Industry Co., Ltd.), because the solid content of the polymer is 30% by mass, 333 mass of polymer Part corresponds to 100 parts by mass of polyurethane), 10 μm flaky silver particles (trade name: FA-D-4, manufactured by DOWA Electronics) 400 parts by mass, 1 μm spherical silver particles (trade names: AG2-1C, DOWA) 400 parts by mass of Electronics Co., Ltd.) and 150 parts by mass of a printing solvent (butyl carbitol, Sankyo Chemical Co., Ltd.) are weighed and stirred to homogenize. Then, the solution after stirring is transferred to a container having a wide mouth in order to widen the area in contact with the atmosphere. Then, the solution is allowed to stand for about a day with occasional stirring to sufficiently evaporate MEK, toluene and isopropyl alcohol having a low boiling point. In this way, a wiring paint is prepared.

  The coating layer paint is prepared by the following procedure. First, 100 parts by mass of a polymer (acrylic rubber, trade name: Nipol AR51, manufactured by Nippon Zeon), vulcanization aid (stearic acid, trade name: Lunac S30, manufactured by Kao Corporation), 1.00 parts by weight, vulcanization accelerator (Zinc dimethyldithiocarbamate, trade name: Noxeller PZ, manufactured by Ouchi Shinsei Chemical) 2.50 parts by mass, vulcanization accelerator (Ferric dimethyldithiocarbamate, trade name: Noxeller TTFE, manufactured by Ouchi Shinsei Chemical) 0.50 part by mass is weighed, and rubber kneading is performed using a roll. Then, a rubber compound is prepared. Subsequently, the prepared rubber compound is immersed in 300 parts by mass of a printing solvent (ethylene glycol monobutyl ether acetate, manufactured by Daicel Chemical Industries, Ltd.), and stirred to make it uniform. In this way, a coating layer paint is prepared.

  In the front side electrode printing process, the electrode paint prepared in the paint preparation process is printed on the upper surface of the dielectric layer 20. FIG. 4 shows a schematic diagram of the first half of the front-side electrode printing process of the method for manufacturing the capacitive surface pressure distribution sensor of the present embodiment. FIG. 5 shows a schematic diagram of the latter half of the process.

  As shown in FIGS. 4 and 5, in this step, the electrode paint 80 is printed on the upper surface of the dielectric layer 20 by the screen printer 9. The screen printing machine 9 includes a table 90, a frame 91, a screen mask 92, and a squeegee 93. A dielectric layer 20 is placed on the table 90. The screen mask 92 is disposed above the table 90. The screen mask 92 is stretched on the frame 91. The screen mask 92 has holes 920 corresponding to the front side electrodes 01X to 16X (see FIG. 3). The squeegee 93 is disposed above the screen mask 92.

  In this step, first, electrode paint 80 is placed on the upper surface of the screen mask 92. Subsequently, the lower surface of the screen mask 92 is pressed against the upper surface of the dielectric layer 20. Then, the electrode paint 80 on the upper surface of the screen mask 92 is pushed into the hole 920 by moving the squeegee 93 in the Y direction. Then, the front side electrodes 01X to 16X (see FIG. 3) are printed on the portions corresponding to the holes 920 on the upper surface of the dielectric layer 20. Thereafter, the front side electrodes 01X to 16X are heated to vulcanize the polymer.

  In the front side wiring printing step, the wiring coating material prepared in the coating material preparation step is printed on the upper surface of the dielectric layer 20 using the screen printer 9 as in the front side electrode printing step. Then, the front-side wirings 01x to 16x (see FIG. 2) are arranged on the upper surface of the dielectric layer 20. Thereafter, the front wirings 01x to 16x are dried. The holes 920 of the screen mask 92 are arranged corresponding to the front side wirings 01x to 16x.

  In the front side insulating coating layer printing step, similarly to the front side electrode printing step, using the screen printer 9, the top surface of the dielectric layer 20, the front side electrodes 01X to 16X and the front side wirings 01x to 16x was prepared in the paint preparation step. Print overcoat paint. Then, the front-side insulating coating layer 21 (see FIG. 3) is disposed on the top surfaces of the dielectric layer 20, the front-side electrodes 01X to 16X, and the front-side wirings 01x to 16x. Thereafter, the front insulating coating layer 21 is heated to vulcanize the polymer. The holes 920 of the screen mask 92 are arranged corresponding to the front insulating coating layer 21.

  In the back side electrode printing step, similarly to the front side electrode printing step, it was prepared in the paint preparation step using the screen printer 9 on the lower surface of the dielectric layer 20 (the lower surface in FIG. 3. The electrode paint 80 is printed. Then, the back-side electrodes 01Y to 16Y (see FIG. 2) are disposed on the lower surface of the dielectric layer 20. Thereafter, the back-side electrodes 01Y to 16Y are heated to vulcanize the polymer.

  In the back side wiring printing process, the wiring paint prepared in the paint preparation process is printed on the lower surface of the dielectric layer 20 by using the screen printer 9 as in the front side wiring printing process. Then, backside wirings 01y to 16y (see FIG. 2) are arranged on the lower surface of the dielectric layer 20. Thereafter, the back side wirings 01y to 19y are dried.

  In the back side insulating coating layer printing step, similarly to the front side insulating coating layer printing step, the screen printing machine 9 is used to apply the dielectric layer 20, the back side electrodes 01Y to 16Y, and the bottom surfaces of the back side wirings 01y to 16y in the paint preparation step. The prepared coating layer paint is printed. And the back side insulation coating layer 22 (refer FIG. 3) is arrange | positioned on the lower surface of the dielectric layer 20, back side electrode 01Y-16Y, and back side wiring 01y-16y. Thereafter, the back insulating coating layer 22 is heated to vulcanize the polymer. In this way, the capacitive surface pressure distribution sensor 1 of the present embodiment is manufactured.

[Movement of capacitive surface pressure distribution sensor]
Next, the movement of the capacitive surface pressure distribution sensor 1 of this embodiment will be described. First, a capacitance calculation method of the calculation unit 3 will be described. This capacitance calculation method is executed for each of the detection units A0101 to A1616.

  As shown in the above equation (2), the electrical resistance of the object is proportional to the length. The front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y ensure conductivity by conductive carbon black. For this reason, the electrical resistances of the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y are larger than those of the front-side wirings 01x to 16x and the back-side wirings 01y to 16y.

  Further, the distances (corresponding to the length L in Expression (2)) from the front side connection portions 01X1 to 16X1 to the detection portions A0101 to A1616 in the front side electrodes 01X to 16X are not constant. That is, the electrical resistance from the front side connection portions 01X1 to 16X1 to the detection portions A0101 to A1616 in the front side electrodes 01X to 16X is not constant. As an example, focusing on the front side electrode 01X in FIG. 2, the distance from the front side connection unit 01X1 to the detection unit A0116 is longer than the distance from the front side connection unit 01X1 to the detection unit A0101. Therefore, the electrical resistance from the front side connection unit 01X1 to the detection unit A0116 is larger than the electrical resistance from the front side connection unit 01X1 to the detection unit A0101. Similarly, the electrical resistance from the back side connection portions 01Y1 to 16Y1 to the detection portions A0101 to A1616 in the back side electrodes 01Y to 16Y is not constant.

  FIG. 6 shows an equivalent circuit diagram of an arbitrary front side electrode-detection unit-back side electrode of the capacitive surface pressure distribution sensor of the present embodiment. As shown in FIG. 6, the optional front side electrodes 01X to 16X—detecting portions A0101 to A1616—back side electrodes 01Y to 16Y are equivalent to an RC series circuit. That is, the impedance Z of the arbitrary front side electrodes 01X to 16X-detecting portions A0101 to A1616-back side electrodes 01Y to 16Y is the electrical resistance rX from the front side connecting portions 01X1 to 16X1 to the detecting portions A0101 to A1616 in the front side electrodes 01X to 16X. And the capacitive reactance 1 / ωC of the detection parts A0101 to A1616 and the electrical resistance rY from the back side connection parts 01Y1 to 16Y1 to the detection parts A0101 to A1616 in the back side electrodes 01Y to 16Y.

  On the other hand, from the sensor body 2, the calculation unit 3 receives the impedance Z of any front side electrode 01X to 16X-detection unit A0101 to A1616-back side electrode 01Y to 16Y, and the lead angle (phase) θ of the current with respect to the voltage (described later). Are input).

In order to calculate the capacitance C of the detection units A0101 to A1616 with high accuracy in the calculation unit 3, it is necessary to separate the influence of the electrical resistances rX and rY from the impedance Z. FIG. 7 shows an impedance vector diagram of the RC series circuit. Moreover, the impedance relational expression of RC series circuit is shown to Formula (3)-(5).

  Here, the electric resistance R is the sum of the electric resistance rX and the electric resistance rY. Ω is an angular frequency. The angular frequency ω is known.

  The ROM 33 stores equations (3) and (5) in advance. The CPU calculates the electric resistance R by substituting the impedance Z and the phase θ temporarily stored in the RAM 32 into the equation (3). Then, the capacitance C is calculated by substituting the impedance Z, the electric resistance R, and the angular frequency ω into the equation (5).

  Next, the movement of the capacitance-type surface pressure distribution sensor when measuring the measurement object will be described. First, before placing the measurement object on the sensor body 2, the capacitance C is calculated for each of the detection units A0101 to A1616 using the capacitance calculation method. That is, the capacitance C is calculated so as to scan from the detection unit A0101 to the detection unit A1616. The calculated capacitance C is stored in the RAM 32 for each of the detection units A0101 to A1616.

  Subsequently, the measurement object is placed on the sensor main body 2, and the capacitance C is calculated for each of the detection units A0101 to A1616 using the capacitance calculation method in the same manner as before the placement. That is, the capacitance C is calculated so as to scan from the detection unit A0101 to the detection unit A1616. The calculated capacitance C is stored in the RAM 32 for each of the detection units A0101 to A1616.

  Then, the CPU 31 calculates the surface pressure applied to the sensor body 2 from the change amount ΔC of the capacitance C before and after placing the measurement object. 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 A1616 is calculated. Then, the surface pressure is displayed on the screen of the display 34 for each of the detection units A0101 to A1616.

  Further, the CPU 31 displays the total load applied to all the detection units A0101 to A1616, that is, the sensor main body 2 on the screen of the display 34 by integrating the variation ΔC of the capacitance C of each detection unit A0101 to A1616. You can also.

[Function and effect]
Next, the function and effect of the capacitive surface pressure distribution sensor 1 of the present embodiment will be described. According to the capacitive surface pressure distribution sensor 1 of the present embodiment, the dielectric layer 20 is made of ether urethane rubber. For this reason, compared with the case where the dielectric layer 20 is air, the electrostatic capacitance C output from detection part A0101-A1616 becomes large. Further, the change amount ΔC of the capacitance C increases.

  The front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y are both strip-shaped. And detection part A0101-A1616 is arrange | positioned using the cross | intersection part of front side electrode 01X-16X and back side electrode 01Y-16Y. For this reason, the number of electrodes is reduced. In addition, the number of wirings is reduced. That is, a total of 256 detection units A0101 to A1616 are arranged in the sensor body 2. Here, if electrodes are arranged for each of the detection portions A0101 to A1616, 256 front side electrodes and 256 back side electrodes are required. On the other hand, according to the capacitance-type surface pressure distribution sensor 1 of the present embodiment, a total of 32 front-side electrodes 01X to 16X and back-side electrodes 01Y to 16Y are provided in order to secure 256 detection units A0101 to A1616. It is only necessary to arrange (= 16 + 16). For this reason, the number of electrodes is reduced.

  The front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y are formed including acrylic rubber and conductive carbon black. For this reason, when a load is applied from the measurement object, the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y can expand and contract together with the dielectric layer 20 according to the load. Therefore, the expansion and contraction of the dielectric layer 20 is less likely to be regulated by the front side electrodes 01X to 16X or the back side electrodes 01Y to 16Y.

  Further, the front side wirings 01x to 16x and the back side wirings 01y to 16y are formed to include urethane rubber and silver powder. For this reason, when a load is applied from the measurement object, the front-side wirings 01x to 16x and the back-side wirings 01y to 16y can be expanded and contracted according to the load. Accordingly, the expansion and contraction of the dielectric layer 20 is less likely to be regulated by the front side wirings 01x to 16x or the back side wirings 01y to 16y.

  Further, according to the capacitance-type surface pressure distribution sensor 1 of the present embodiment, the impedance R, the electrical resistance rX from the front side connection parts 01X1 to 16X1 to the detection parts A0101 to A1616, and the detection part from the back side connection parts 01Y1 to 16Y1. The electric resistance rY from A0101 to A1616 is separated. That is, the capacitance C of the detection units A0101 to A1616 is extracted from the impedance Z. For this reason, the measurement accuracy of the surface pressure distribution is high.

  Further, according to the capacitance-type surface pressure distribution sensor 1 of the present embodiment, the calculation unit 3 integrates the change amount ΔC of the capacitance C of the detection units A0101 to A1616, so that the total load applied to the sensor main body 2 is calculated. Can be calculated. For this reason, the weight of the measurement object can be detected.

  Further, according to the capacitive surface pressure distribution sensor 1 of the present embodiment, the front side electrodes 01X to 16X are arranged at substantially equal intervals in the X direction and the Y direction over the entire surface of the sensor body 2. Similarly, the back-side electrodes 01Y to 16Y are disposed at substantially equal intervals in the X direction and the Y direction over the entire surface of the sensor body 2. Further, the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y are arranged substantially orthogonally when viewed from the vertical direction. Therefore, the detection units A0101 to A1616 can be dispersed on the entire surface of the sensor body 2. Therefore, the area of the portion where the surface pressure can be detected in the entire sensor body 2 can be increased.

  Further, according to the capacitive surface pressure distribution sensor 1 of the present embodiment, the front side electrodes 01X to 16X, the front side wirings 01x to 16x, the back side electrodes 01Y to 16Y, and the back side wirings 01y to the dielectric layer 20 are formed by a screen printing method. 16y is arranged. For this reason, it is possible to integrate the components essential for measuring the surface pressure relatively easily. Therefore, the productivity of the sensor main body 2, and thus the capacitance type surface pressure distribution sensor 1, is high.

  Further, the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y are directly printed on the dielectric layer 20. For this reason, positioning with front side electrode 01X-16X and back side electrode 01Y-16Y is easy. Therefore, the detection units A0101 to A1616 can be accurately arranged at desired positions.

  In the capacitive surface pressure distribution sensor 1 of the present embodiment, a front-side insulating coating layer 21 and a back-side insulating coating layer 22 are disposed. For this reason, it can suppress that the front side electrodes 01X-16X and the front side wiring 01x-16x and the member outside the electrostatic capacitance type surface pressure distribution sensor 1 conduct | electrically_connect. In addition, the back-side electrodes 01Y to 16Y and the back-side wirings 01y to 16y can be prevented from conducting to the external member of the capacitive surface pressure distribution sensor 1.

  Moreover, the relationship between the compounding quantity of electroconductive carbon black and the electrical resistance of the elastomer composition which forms the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y of the capacitive surface pressure distribution sensor 1 of the present embodiment is expressed. In the percolation curve, the blending amount (critical volume fraction: φc) of the conductive carbon black at the first inflection point where the electrical resistance is lowered and the insulator-conductor transition occurs is about 4 vol%. For this reason, conductive carbon black tends to form aggregates. Therefore, the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y having good conductivity can be obtained with a relatively small amount of conductive carbon black.

<Second embodiment>
The difference between the capacitance-type surface pressure distribution sensor of the present embodiment and the capacitance-type surface pressure distribution sensor of the first embodiment is that the sensor body has an insulating cylinder member. Therefore, only the differences will be described here.

  FIG. 8 is a cross-sectional view in the Y direction of the capacitive surface pressure distribution sensor of the present embodiment. In addition, about the site | part corresponding to FIG. 3, it shows with the same code | symbol. As shown in FIG. 8, the sensor main body 2 includes an insulating cylinder member 25. The insulating cylinder member 25 includes a front side insulating sheet 250 and a back side insulating sheet 251. The materials of the front side insulating sheet 250 and the back side insulating sheet 251 are the same as the materials of the front side insulating coating layer and the back side insulating coating layer of the first embodiment.

  A total of 16 front side electrodes 01 </ b> X to 16 </ b> X are printed on the inner surface of the front side insulating sheet 250. A total of 16 back-side electrodes 16Y are printed on the inner surface of the back-side insulating sheet 251. Inside the insulating cylindrical member 25, a dielectric layer 20 is interposed between the front side electrodes 01X to 16X and the back side electrode 16Y.

  The manufacturing method of the capacitance type surface pressure distribution sensor of the present embodiment includes a paint preparation step, a front side electrode printing step, a front side wiring printing step, a back side electrode printing step, a back side wiring printing step, and an insulating cylinder member production. And a dielectric layer insertion step. In the paint preparation step, an electrode paint and a wiring paint are prepared. In the front side electrode printing step, the front side electrodes 01X to 16X are printed on the inner surface of the front side insulating sheet 250 by a screen printer. Then, the front side electrodes 01X to 16X are vulcanized. In the front side wiring printing step, the front side wiring is printed on the inner surface of the front side insulating sheet 250 by a screen printer. Then, the front wiring is dried. In the back side electrode printing step, the back side electrode 16Y is printed on the inner surface of the back side insulating sheet 251 by a screen printer. Then, the back electrode 16Y is vulcanized. In the back side wiring printing step, the back side wiring is printed on the inner surface of the back side insulating sheet 251 by a screen printer. Then, the back side wiring is dried. In the insulating cylinder member manufacturing step, the front side insulating sheet 250 and the back side insulating sheet 251 are bonded together. And the insulation cylinder member 25 is produced. In the dielectric layer insertion step, the dielectric layer 20 is inserted into the insulating cylinder member 25.

  The capacitance-type surface pressure distribution sensor 1 of the present embodiment has the same operational effects as the capacitance-type surface pressure distribution sensor of the first embodiment with respect to the parts having the same configuration.

  Further, according to the capacitive surface pressure distribution sensor 1 of the present embodiment, printing is not directly performed on the dielectric layer 20. For this reason, even a material unsuitable for printing (for example, a foam) can be used as the dielectric layer 20. Therefore, the degree of freedom in selecting the material of the dielectric layer 20 is increased.

  Further, according to the capacitance type surface pressure distribution sensor 1 of the present embodiment, the surface pressure measurement of the dielectric layer 20, the front side electrodes 01X to 16X, the front side wiring, the back side electrode 16Y, and the back side wiring is provided inside the insulating cylinder member 25. The essential components are housed. For this reason, it can suppress that these members and the member of the outer side of the insulating cylinder member 25 conduct | electrically_connect.

<Others>
The embodiments of the capacitive surface pressure distribution sensor of the present invention have been described above. However, the embodiment is not particularly 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 capacitance C before placing the measurement object and the capacitance C after placing the measurement object are calculated, and the surface pressure distribution is obtained from the change amount ΔC of the capacitance. . However, the surface pressure before placement is obtained from the capacitance C before placing the measurement object, the surface pressure after placement is obtained from the capacitance C after placing the measurement object, and the amount of change in the surface pressure is calculated. The surface pressure distribution may be obtained.

  Further, the number of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y and the crossing angle are not particularly limited. Further, the interval between the adjacent front side electrodes 01X to 16X and the interval between the back side electrodes 01Y to 16Y are not particularly limited. Moreover, you may print antioxidant so that front side wiring 01x-16x and back side wiring 01y-16y may be covered. This can suppress the oxidation of silver in the wiring. Further, the use of the capacitance-type surface pressure distribution sensor 1 is not particularly limited. For example, it may be used as a seat detection sensor for a vehicle seat, a touch sensor, a user position detection sensor in a hot carpet, or the like. The sensor body 2 of the capacitive surface pressure distribution sensor 1 of the present invention is formed of an elastomer and is particularly flexible. For this reason, even if it arrange | positions the electrostatic capacitance type surface pressure distribution sensor 1 of this invention comparatively close to a user's body, there is little discomfort which a user suffers. Therefore, it is particularly suitable for detecting a load (for example, weight) from a human. Further, a personal computer may be used as the calculation unit 3.

  Moreover, in the manufacturing method of the electrostatic capacitance type surface pressure distribution sensor 1, you may perform a process in order of a front side wiring printing process-> front side electrode printing process. Similarly, you may perform a process in order of a back side wiring printing process-> back side electrode printing process.

  Moreover, the printing method in the manufacturing method of the electrostatic capacitance type surface pressure distribution sensor 1 is not specifically limited. In addition to screen printing, inkjet printing, flexographic printing, gravure printing, pad printing, lithography, or the like may be used.

  Moreover, the elastomer which comprises the dielectric layer 20 can be suitably selected from rubber | gum and a thermoplastic elastomer. The elastomer is not particularly limited. For example, from the viewpoint of increasing the capacitance, a high relative dielectric constant is desirable. For example, 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 preferably used. The elastomer may or may not be cross-linked. Moreover, what is necessary is just to adjust a detection sensitivity or a detection range according to a use by adjusting the Young's modulus of an elastomer. That is, the dielectric layer 20 having various Young's moduli can be selected according to the magnitude of the load on the measurement object. In particular, when the load of the measurement object is small, it is preferable to use a foam as the elastomer of the dielectric layer 20. The reason is that since the foam has a small Young's modulus, the dielectric layer 20 is sufficiently deformed even when the load on the object to be measured is small. That is, it is because the surface pressure and load of the measurement object can be reliably detected.

  Examples of suitable elastomers include silicone rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and urethane rubber.

  The thickness of the dielectric layer is not particularly limited. For example, the detection sensitivity can be increased by increasing the capacitance C proportional to the reciprocal of the thickness of the dielectric layer 20 (distance d between the electrodes) as shown in Equation (1) from the viewpoint of downsizing the sensor body 2. From the viewpoint of improving the above, it is desirable that the thickness be 1 μm or more and 3000 μm or less. 50 μm or more and 500 μm or less is more preferable.

  Moreover, the elastomer which comprises the front side electrodes 01X-16X and the back side electrodes 01Y-16Y may be the same as the elastomer used for the dielectric layer 20, and may differ. When the front side electrodes 01X to 16X, the back side electrodes 01Y to 16Y, and the dielectric layer 20 are made of the same elastomer, the followability of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y with respect to deformation of the dielectric layer 20 is improved. Further, adhesion between the dielectric layer 20 and the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y is improved. For this reason, even if subjected to repeated fatigue, peeling between the dielectric layer 20, the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y is suppressed, and the reliability is improved.

  Examples of elastomers suitable for the front electrodes 01X to 16X and the back electrodes 01Y to 16Y include silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, Examples include epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and urethane rubber.

  Moreover, in the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y, the shape of the conductive filler blended in the elastomer is not particularly limited, such as a spherical shape, a needle shape, or a prism shape. For example, the aspect ratio (the ratio of the long side to the short side) of the conductive filler is preferably 1 or more. For example, when a needle-like conductive filler having a relatively large aspect ratio is used, a three-dimensional conductive network can be easily formed, and high conductivity can be realized with a small amount. In addition, it is possible to suppress a change in conductivity when the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y expand and contract.

  Moreover, when selecting a conductive filler, it is good to consider an average particle diameter, compatibility with an elastomer, etc. For example, when a spherical conductive filler is employed, the average particle diameter (primary particles) of the conductive filler is desirably 0.01 μm or more and 0.5 μm or less. When the thickness is less than 0.01 μm, the cohesiveness is high, and it is difficult to uniformly disperse the electrode paint. Preferably it is 0.03 micrometer or more. On the other hand, when it exceeds 0.5 μm, it becomes difficult to form aggregates (secondary particles). Preferably it is 0.1 micrometer or less. The critical volume fraction (φc) in the percolation curve can be adjusted within a desired range by appropriately adjusting the combination of the conductive filler and the elastomer, the average particle diameter of the conductive filler, and the like.

  Moreover, in order to express desired electroconductivity, it is desirable that the conductive filler is blended at a ratio equal to or higher than the critical volume fraction (φc) in the percolation curve. On the other hand, when the filling rate of the conductive filler exceeds 30 vol%, mixing with the elastomer becomes difficult, and molding processability is deteriorated. In addition, the stretchability of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y is lowered. For this reason, it is desirable that it is 30 vol% or less. Further, from the viewpoint of securing the stretchability of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y, it is desirable that a relatively small amount of a conductive filler is blended to express high conductivity. Therefore, the filling rate of the conductive filler is desirably 25 vol% or less when the volume of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y is 100 vol%. It is more preferable that it is 15 vol% or less.

  Further, the thicknesses of the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y are not particularly limited. From the viewpoint of downsizing the sensor body 2 in consideration of the followability to the dielectric layer 20, it is preferably 1 μm or more and 100 μm or less. In addition, in order to improve followability to deformation of the dielectric layer 20, it is desirable that the Young's modulus of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y be 0.1 MPa or more and 10 MPa or less. Similarly, the elongation at break in the tensile test (JIS K6251) is desirably 200% or more.

  The electrical resistance of the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y is preferably 100 kΩ or less in the thickness direction and the surface direction, and more preferably 10 kΩ or less. Here, even if the front side electrodes 01X to 16X and the back side electrodes 01Y to 16Y expand and contract, the change in conductivity is small. For example, the inter-terminal resistance (R1) when the front-side electrodes 01X to 16X and the back-side electrodes 01Y to 16Y are expanded in one direction and the inter-terminal distance is increased by 100% is compared to the inter-terminal resistance (R0) before expansion. If it is 10 times or less (R1 / R0 ≦ 10), it can be said that “the change in conductivity is small even if it expands and contracts”.

  Moreover, in addition to the said elastomer and a conductive filler, various additives may be mix | blended with the front side electrodes 01X-16X and the back side electrodes 01Y-16Y. Examples of the additive include a crosslinking agent, a vulcanization accelerator, a vulcanization aid, an antiaging agent, a plasticizer, a softening agent, and a colorant.

  Moreover, the elastomer which comprises the front side wiring 01x-16x and the back side wiring 01y-16y may be the same as the elastomer used for the dielectric layer 20, the front side electrodes 01X-16X, and the back side electrodes 01Y-16Y, and may differ. For example, silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber, etc. Is preferred.

  Moreover, the kind of electroconductive particle will not be specifically limited if the electroconductivity is high. For example, metal powder such as silver, copper, gold, or nickel may be employed. Moreover, in order to express desired conductivity, the filling rate of the conductive particles in the elastomer is desirably 20 vol% or more when the volume of the front wirings 01x to 16x or the back wirings 01y to 16y is 100 vol%. . Moreover, in order to suppress the reduction | decrease in the elasticity of front side wiring 01x-16x and back side wiring 01y-16y, it is desirable that the filling rate of the electroconductive particle in an elastomer is 50 vol% or less.

  Moreover, as a material which forms the front side insulating coating layer 21, the back side insulating coating layer 22, and the insulating cylinder member 25, for example, acrylic rubber, urethane rubber, silicone rubber, ethylene propylene copolymer rubber, natural rubber, styrene-butadiene rubber, Sheets of acrylonitrile butadiene rubber, epichlorohydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene rubber or the like may be used.

  Hereinafter, a surface pressure measurement experiment performed on the capacitance-type surface pressure distribution sensor 1 (see FIGS. 2 and 3) according to the first embodiment will be described.

<Experiment method>
The area of the arrangement | positioning part of the front side electrodes 01X-16X and back side electrodes 01Y-16Y of the sensor main body 2 was 552 cm < ² >. The shape of the weight that presses the sensor body 2 was a rectangular parallelepiped. The area of the surface that presses the sensor body 2 in the weight (load application area) was 324 cm ² , 180 cm ² , and 149 cm ² . In these three patterns of load application areas, changes in capacitance obtained from the detection units A0101 to A1616 were observed when the load was increased.

<Experimental result>
FIG. 9 is a graph showing the relationship between the load and the integrated capacitance value. 9, the load application area is in either case ^{324cm 2, 180cm 2, 149cm 2} , when the load increases, the integral of the electrostatic capacitance obtained from the capacitance integration value (= detector A0101~A1616 It can be seen that things are getting bigger. That is, it can be seen that the total load applied to the sensor body 2 from the weight is proportional to the integrated capacitance value.

FIG. 10 is a graph showing the relationship between the surface pressure and the capacitance. From FIG. 10, even when the load application area is any of 324 cm ² , 180 cm ² , and 149 cm ² , when the surface pressure (= load / load application area) increases, the capacitance (= each of the detection units A0101 to A1616). It can be seen that the (capacitance) increases. It can also be seen that the surface pressure is proportional to the capacitance regardless of the load application area. Further, it can be seen from FIG. 10 that the surface pressure can be calculated from the capacitance.

FIG. 11 is a graph showing the capacitance distribution when the weight load application area is 149 cm ² and the load is 3.4 kgf. The number of detection units that have detected the electrostatic capacitance is 70 out of 256 total detection units A0101 to A1616. The integrated capacitance value is 10728 pF. The surface pressure is 2236 (Pa) [= (3.4 (kgf) × 9.8 (N / kgf)) / (149 × 10 ⁻⁴ (m ² ))]. The capacitance change per detection unit A0101-A1616 (= capacitance after load application-capacitance before load application) is 153.3 (pF / piece) [= 10728 (pF) / 70 (pieces) ]]. It can be seen from FIG. 11 that the capacitance distribution corresponds to the shape (substantially square) of the weight load application surface.

It is a schematic diagram which shows the relationship between the compounding quantity of the electroconductive filler in an elastomer composition, and an electrical resistance. It is an upper surface penetration figure of a capacity type surface pressure distribution sensor of a first embodiment. It is the III-III direction sectional drawing of FIG. It is a schematic diagram of the front-side electrode printing process first half of the manufacturing method of the same capacitance type surface pressure distribution sensor. It is a schematic diagram of the latter half of the process. It is an equivalent circuit diagram of the arbitrary front side electrode-detection part-back side electrode of the same capacitance type surface pressure distribution sensor. It is an impedance vector diagram of RC series circuit. It is a Y direction sectional view of a capacitance type surface pressure distribution sensor of a second embodiment. It is a graph which shows the relationship between a load and an electrostatic capacitance integral value. It is a graph which shows the relationship between a surface pressure and an electrostatic capacitance. It is a graph which shows an electrostatic capacitance distribution in case the load application area of a weight is 149 cm < ² > and a load is 3.4 kgf.

Explanation of symbols

1: Capacitive surface pressure distribution sensor, 2: sensor body, 3: calculation unit, 9: screen printer.
20: Dielectric layer, 21: Front side insulating coating layer, 22: Back side insulating coating layer, 23: Front side wiring connector, 24: Back side wiring connector, 25: Insulating cylindrical member, 30: Power supply circuit, 31: CPU, 32: RAM, 33: ROM, 34: display, 80: electrode paint, 90: table, 91: frame, 92: screen mask, 93: squeegee.
101: Elastomer, 102: Conductive filler, 250: Front insulating sheet, 251: Back insulating sheet, 920: Hole.
01X1 to 16X1: Front side connection part, 01X to 16X: Front side electrode, 01Y1 to 16Y1: Back side connection part, 01Y to 16Y: Back side electrode, 01x to 16x: Front side wiring, 01y to 16y: Back side wiring, A0101 to A1616: Detection part , P1: Conductive path.

Claims (8)

An elastomeric dielectric layer;
At least one disposed on the front side of the dielectric layer, formed of an elastomer and a conductive filler filled in the elastomer, and formed into a strip-shaped front electrode having a front side connection portion;
At least one disposed on the back side of the dielectric layer, formed of an elastomer and a conductive filler filled in the elastomer, and formed into a strip-shaped back side electrode having a back side connection portion;
A plurality of detection units formed by crossing the front-side electrode and the back-side electrode when viewed from the front-back direction;
A front-side wiring connected to the front-side connection portion, formed of an elastomer and conductive particles filled in the elastomer, and having a lower electrical resistance than the front-side electrode;
A back-side wiring connected to the back-side connecting portion, formed of an elastomer and conductive particles filled in the elastomer, and having a lower electrical resistance than the back-side electrode;
A sensor body that can be extended and contracted integrally,
An electrical resistance electrically connected to the front side wiring and the back side wiring, from an impedance detected from the front side wiring and the back side wiring, an electrical resistance depending on a distance from the front side connection part to the detection part in the front side electrode, and the back side The electrical resistance according to the distance from the backside connection part to the detection part in the electrode is separated, the capacitance of the detection part is extracted, and the surface pressure distribution in the sensor main body from the capacitance of the detection part An arithmetic unit for calculating
A capacitance-type surface pressure distribution sensor comprising:   The capacitance-type surface pressure distribution sensor according to claim 1, wherein the calculation unit calculates a total load applied to the sensor body by integrating the capacitances of the plurality of detection units. The front side electrodes are arranged in a plurality of rows,
The back side electrodes are arranged in a plurality of rows,
The capacitive surface pressure distribution sensor according to claim 1 or 2, wherein the plurality of front-side electrodes and the plurality of back-side electrodes are disposed substantially orthogonally when viewed from the front-back direction. The front side electrode and the front side wiring are printed on the surface of the dielectric layer,
4. The capacitive surface pressure distribution sensor according to claim 1, wherein the back-side electrode and the back-side wiring are printed on a back surface of the dielectric layer. 5. The sensor body is further printed by directly or indirectly covering the front side electrode and the front side wiring, and the front side insulating coating layer for insulating the front side electrode and the front side wiring from the outside, the back side electrode, and the A back side insulating coating layer that is printed directly or indirectly covering the back side wiring, and that insulates the back side electrode and the back side wiring from the outside;
The electrostatic capacitance type surface pressure distribution sensor according to claim 1, comprising: The sensor body is further cylindrical and has an insulating cylinder member that insulates the inside and outside of the cylinder,
The dielectric layer is accommodated in the insulating cylinder member,
The front side electrode and the front side wiring are printed on the inner surface of the insulating cylinder member and facing the surface of the dielectric layer,
4. The capacitance type according to claim 1, wherein the back-side electrode and the back-side wiring are printed on an inner surface of the insulating cylinder member and facing a back surface of the dielectric layer. 5. Surface pressure distribution sensor.   The capacitive surface pressure distribution sensor according to any one of claims 1 to 6, wherein at least one of the front-side electrode and the back-side electrode has a surface resistance between both longitudinal ends of 100 kΩ or less.   The capacitance type according to any one of claims 1 to 7, wherein the conductive filler is composed of one or more kinds selected from conductive carbon black, carbon nanotubes, carbon nanotube derivatives, graphite, and conductive carbon fibers. Surface pressure distribution sensor.

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