Tactile sensor

Abstract

To provide a tactile sensor having a wiring structure that reduces the effect on detection sensitivity.SOLUTION: The tactile sensor includes five first pressure-sensitive elements and a plurality of wiring provided on a first substrate and five second pressure-sensitive elements provided on a second substrate. The five first pressure-sensitive elements include two first detection elements aligned in a predetermined first direction, two second detection elements aligned in a second direction, and one third detection element. The plurality of wiring includes wiring connected to the two first detection elements, wiring connected to the two second detection elements, and wiring connected to the third detection element. The wiring connected to the two first detection elements has a portion that outputs the potential between the two first detection elements. The wiring connected to the two second detection elements includes a portion that outputs the intermediate potential of the two second detection elements. Within the area enclosed by the wiring connected to the two first detection elements, the wiring connected to the two second detection elements and the wiring connected to the third detection element are provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tactile sensor capable of detecting pressure and shear force.

Background Art

[0002] As a tactile sensor for detecting pressure and shear force, there is known one having a structure in which a conductor layer or a resin layer is sandwiched between two opposed electrodes. This tactile sensor can detect pressure and shear force based on a change in a physical quantity between the electrodes by deforming the conductor layer or the resin layer by an external force (Patent Documents 1 to 3). Further, in a general tactile sensor, a change in resistance value between electrodes formed between two opposed substrates (upper and lower substrates) is measured via wirings connected to the electrodes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since a tactile sensor for detecting pressure and shear force includes electrodes for pressure detection and a plurality of electrodes for shear force detection, the arrangement of a plurality of wirings connected to each electrode becomes complicated. If the wirings cross each other or the number of wirings passing between adjacent electrodes increases, it may affect the detection sensitivity of the tactile sensor, so there is room for improvement in the wiring structure.

[0005] Therefore, an object of the present invention is to provide a tactile sensor having a wiring structure that hardly affects detection sensitivity.

Means for Solving the Problem

[0006] One aspect of the present invention for solving the above problems includes a first base material, a second base material facing one surface of the first base material, five first pressure-sensitive elements provided on one surface of the first base material, and five second pressure-sensitive elements provided on the surface of the second base material facing the first base material and facing each of the five first pressure-sensitive elements, and a plurality of wirings provided on one surface of the first base material. The first pressure-sensitive element and the second pressure-sensitive element are elements whose resistance value changes in response to a pressure change. The five first pressure-sensitive elements include two first detection elements aligned in a predetermined first direction, two second detection elements aligned in a second direction orthogonal to the first direction, and one third detection element. The two first detection elements are arranged at equal intervals around the third detection element, and the two second detection elements are arranged at equal intervals around the third detection element. The plurality of wirings include a wiring connected to the two first detection elements, a wiring connected to the two second detection elements, and a wiring connected to the third detection element. The wiring connected to the two first detection elements has a portion that outputs the potential in the middle of the two first detection elements. The wiring connected to the two second detection elements has a portion that outputs the potential in the middle of the two second detection elements. The wiring connected to the two second detection elements and the wiring connected to the third detection element are provided in the region surrounded by the wiring connected to the two first detection elements. It is a tactile sensor.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a tactile sensor having a wiring structure that has little influence on detection sensitivity.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the shape and number of each component constituting the tactile sensor according to the embodiment are examples and do not limit the present invention. Also, for the sake of simplicity of explanation, the drawings are drawn at a ratio different from the actual dimensions, but this does not impair the gist of the technology according to the present invention.

[0010] <First Embodiment> FIG. 1 is a schematic diagram showing a schematic configuration of a tactile sensor according to a first embodiment of the present invention. More specifically, FIG. 1(a) is a plan view of the tactile sensor, and FIG. 1(b) is a cross-sectional view taken along line A-A' shown in FIG. 1(a). FIG. 2 is a schematic diagram of the first base material side of the tactile sensor. More specifically, FIG. 2(a) is a plan view of the first base material side of the tactile sensor, and FIG. 2(b) is a cross-sectional view taken along line B-B' shown in FIG. 2(a). FIG. 3 is a schematic diagram of the second base material side of the tactile sensor. More specifically, FIG. 3(a) is a plan view of the second base material side of the tactile sensor, and FIG. 3(b) is a cross-sectional view taken along line C-C' shown in FIG. 3(a). In FIGS. 1(b), 2(b), and 3(b), for the sake of convenience, the wirings described later are omitted.

[0011] The tactile sensor 100 is a sensor capable of detecting pressure and shear force (shearing force) applied to a base material, and includes a first base material 1, a second base material 2, five first pressure-sensitive elements 10 provided on one surface of the first base material 1, five second pressure-sensitive elements 20 provided opposite to each of the first pressure-sensitive elements 10 on the surface of the second base material 2 facing the first base material 1, and a plurality of wirings provided on one surface of the first base material 1. Note that the pressure indicates a force component in the direction perpendicular to the sensor surface (the Z-axis direction in FIG. 1), and the shear force indicates a force component in the surface direction of the base material (the Z-axis and Y-axis directions in FIG. 1).

[0012] The first pressure-sensitive element 10 and the second pressure-sensitive element 20 are elements whose resistance value changes according to the load. The tactile sensor 100 includes an output circuit such as a bridge circuit that converts the resistance value generated between the first pressure-sensitive element 10 and the second pressure-sensitive element 20 into a voltage and outputs it. The first base material 1 and the second base material 2 are adhered via a connection layer 5 provided so as to surround all the first pressure-sensitive elements 10 and the second pressure-sensitive elements 20. Further, if necessary, a buffer material for inputting a load to the tactile sensor 100 may be provided on the surface of the second base material 2 opposite to the first base material 1. The buffer material is provided in a region inside the inner circumference of the connection layer 5 in a plan view. By providing the buffer material, the detection region of the tactile sensor 100 becomes clear, and since the input load is dispersed within the buffer material, it becomes easier to apply a force stably to all the pressure-sensitive elements. The detection region is a region where a load should be input for the tactile sensor 100 to perform accurate detection, and corresponds to the region of the smallest circle including the first pressure-sensitive element 10 and the second pressure-sensitive element 20 in a plan view.

[0013] (Base material) The material of the first substrate 1 is not particularly limited as long as it is a substrate on which a pressure-sensitive element and wiring can be formed. A first pressure-sensitive element 10 and a plurality of wirings are provided on the first substrate 1. Also, the material of the second substrate 2 is not particularly limited as long as it is a substrate on which a pressure-sensitive element can be formed. A second pressure-sensitive element 20 is provided on the second substrate 2. The first substrate 1 and the second substrate 2 are preferably flexible sheet-like members. In this case, for example, plastic films such as polyester, polyethylene, polyethylene terephthalate, polyethylene naphthalate (PEN), polybutylene terephthalate, polyamide, polymethyl methacrylate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyimide, polyether ether ketone, ethylene-vinyl alcohol copolymer, cellophane, etc., dimethyl polysiloxane of silicone rubber, and processed papers such as clean paper, coated paper, calendar paper, etc. can be used. Also, when considering the use of the tactile sensor 100 on a living body, as the material of the substrate, polyesters made of homopolymers or copolymers such as polylactic acid, polyglycolic acid, polycaprolactone, acrylic resins, silicones, cellulose derivatives such as cellulose acetate, cellulose propionate, cellulose butyrate, polycarbonate, cycloolefin copolymer, styrene-butadiene elastomer, etc. can be used. Furthermore, depending on the pressure to be sensed, an elastic body such as rubber may be used as a pressure buffer. When using a conductive substrate, it is desirable to coat the surface with an insulating material so as not to affect the sensor, signal line, and electrode. Also, not only a flexible substrate having flexibility but also a flat substrate that does not substantially bend may be used, and it can be appropriately selected according to the use of the tactile sensor 100 and the like. Also, when using a plastic film as the substrate, either an unstretched substrate or a stretched substrate may be used. Considering mechanical strength and dimensional stability, it is preferable to use a stretched substrate such as a uniaxially stretched substrate and a biaxially stretched substrate, particularly a biaxially stretched substrate.

[0014] There are no particular restrictions on the thicknesses of the first substrate 1 and the second substrate 2. However, from the perspective of thinning, it is preferably thin, while it is necessary to have a thickness that can achieve sufficient strength as a substrate. The thickness of the substrate is preferably, for example, 6 μm or more and 200 μm or less. Further, as described in FIG. 1, in the present embodiment, the planar shape of the substrate is a quadrilateral, but the planar shape is not limited to this, and a shape suitable for the place where the sensor is installed, such as a triangle or a circle, can be appropriately selected. However, considering mass productivity, the substrate before cutting is preferably a long object. Further, the materials, thicknesses, and sizes of the first substrate 1 and the second substrate 2 do not have to be the same.

[0015] (Pressure-sensitive element) Five first pressure-sensitive elements 10 are provided on one surface (the surface facing the second substrate 2) of the first substrate 1. The five first pressure-sensitive elements 10 include two first detection elements X1 and X2 aligned in a predetermined first direction (the X-axis direction in FIG. 2), two second detection elements Y1 and Y2 aligned in a second direction (the Y-axis direction in FIG. 2) orthogonal to the first direction, and one third detection element O. The first detection elements X1 and X2 are arranged at equal intervals around the third detection element O, and the second detection elements Y1 and Y2 are arranged at equal intervals around the third detection element O. That is, as shown in FIG. 2(a), the five first pressure-sensitive elements 10 are arranged so that one first pressure-sensitive element 10 (the third detection element O) is centered and the other four first pressure-sensitive elements 10 (the first detection elements X1, X2, Y2, Y2) are rotationally symmetric four times.

[0016] Five second pressure-sensitive elements 20 are provided on the surface of the second substrate 2 facing the one surface of the first substrate 1 so as to face each of the first pressure-sensitive elements 10. The five second pressure-sensitive elements 20 are composed of a fourth detection element X1' facing the first detection element X1, a fourth detection element X2' facing the first detection element X2, a fifth detection element Y1' facing the second detection element Y1, a fifth detection element Y2' facing the second detection element Y2, and a sixth detection element O' facing the third detection element O.

[0017] Wiring is connected to each of the first detection elements X1 and X2, the second detection elements Y1 and Y2, and the third detection element O. The third detection element O and the sixth detection element O' facing it can detect the pressure in the Z-axis direction. Also, the first detection elements X1 and X2 arranged in the X-axis direction and the fourth detection elements X1' and X2' facing them can detect the shearing force in the X-axis direction, and the second detection elements Y1 and Y2 arranged in the Y-axis direction and the fifth detection elements Y1' and Y2' facing them can detect the shearing force in the Y-axis direction.

[0018] As shown in Fig. 2(a), each of the first detection elements X1 and X2, the second detection elements Y1 and Y2, and the third detection element O that make up the first pressure-sensitive element 10 consists of a pair of divided elements 11 and 12 arranged at a predetermined interval. Each of the divided elements 11 and 12 has, in order from the first base material 1 side, a first small electrode 10a and a first small pressure-sensitive layer 10b laminated on the first small electrode 10a.

[0019] As shown in Fig. 3(a), each of the fourth detection elements X1' and X2', the fifth detection elements Y1' and Y2', and the sixth detection element O' that make up the second pressure-sensitive element 20 has, in order from the second base material 2 side, a second electrode 20a, a second small pressure-sensitive layer 21 laminated on one end of the second electrode 20a, and a second small pressure-sensitive layer 22 laminated on one end of the second electrode 20a. The second small pressure-sensitive layers 21 and 22 are arranged at a predetermined interval and are electrically connected by the second electrode 20a. Each of the pair of second small pressure-sensitive layers 21 and 22 overlaps both of the pair of divided elements 11 and 12 in the first pressure-sensitive element 10 arranged at a position facing the second pressure-sensitive element 20 in a plan view. In this embodiment, although the second small pressure-sensitive layers 21 and 22 are arranged at a predetermined interval, instead of the pair of second small pressure-sensitive layers 21 and 22, one second small pressure-sensitive layer may be provided.

[0020] (Small electrode) The first small electrode 10a is provided on one surface of the first substrate 1 (the surface facing the second substrate 2). The second electrode 20a is provided on the surface of the second substrate 2 facing the one surface of the first substrate 1 so as to overlap each of the first small electrodes 10a. Hereinafter, the first small electrode 10a and the second electrode 20a are also simply referred to as "electrodes". Further, the second electrode 20a electrically connects each of the pair of second small pressure-sensitive layers 21, 22 (FIG. 3). As a result, when the divided elements 11, 12 come into contact with the second small pressure-sensitive layers 21, 22 facing each other, a series current path is formed with each first small electrode 10a included in the pair of divided elements 11, 12 arranged on the first substrate 1 side as both ends and passing through the second electrodes 20a included in the pair of second small pressure-sensitive layers 21, 22 arranged on the second substrate 2 side. That is, it is a current path in which the current input from the first substrate 1 side once flows to the second substrate 2 side and then returns to the first substrate 1 side again. For this reason, since it is not necessary to provide wiring for signal extraction for the second substrate 2, the wiring design is simple, the sensor can be easily miniaturized, and defective formation of the wiring can also be reduced.

[0021] The resistivity of the electrode is preferably 1.0×10 -3 Ω·cm or less. Also, the thickness of each electrode is not particularly limited, but is preferably 0.01 μm or more and 30 μm or less, and more preferably 0.05 μm or more and 20 μm or less. If it is less than 0.01 μm, the formed film is likely to be a discontinuous film and sufficient conductivity cannot be obtained. Also, if it exceeds 30 μm, there is a risk that the electrode will crack when the tactile sensor 100 formed on the flexible substrate is bent. Also, the shape and area of the overlapping portions of the respective electrodes facing each other above and below may be the same shape and area, but it is preferable that one electrode has an area larger than the overlapping portion (FIGS. 5 to 6). The area of the overlapping portion is preferably 1 / 5 or more and 2 / 3 or less of the area of the electrode having a relatively large area. If it is less than 1 / 5, the sensitivity of the tactile sensor 100 will decrease. Also, if it exceeds 2 / 3, it becomes difficult to align both electrodes.

[0022] The electrode is not limited in terms of material or formation method as long as it is a conductive material suitable for the specifications of the sensor element to be used. For example, as the material, metals such as Au, Pt, Ag, Cu, Ni, Cr, Rh, Pd, Zn, Co, Ru, W, Os, Ir, Fe, Mn, Ge, Sn, Ga, In, etc., and conductive metal oxides such as ITO (indium tin oxide), ZnO (zinc oxide), SnO2 (tin oxide), etc. can be used. As the formation method, methods using printing methods such as inkjet printing method, screen printing method, offset printing method, gravure offset printing method, reverse offset printing method, etc., or methods of forming a film on the entire surface of a substrate using vapor deposition methods such as vacuum evaporation method, sputtering method, etc., and then patterning the film by an etching method can be used. When using a printing method, a material obtained by mixing the electrode material with a resin and inkifying it so that it can be applied by each printing method can be used. In the case of a vapor deposition method, it may be formed by depositing the material only at a predetermined position using a metal mask. Also, general vinyl wires, etc. may be fixed on the substrate with an adhesive, etc. Any other general signal extraction line and electrode formation method may be used. The electrode may be fabricated in the same process as the wiring. In this embodiment, the shape of the first small electrode 10a is a shape obtained by dividing a circular ring in the circumferential direction and a shape in which one side of a rectangle is curved outward (FIG. 2(a), FIG. 3(a)), but it may be a rectangle, square, circle, etc., and the shape of the second electrode 20a is also appropriately designed accordingly.

[0023] (Small pressure-sensitive layer) The first small pressure-sensitive layer 10b is laminated on each of the first small electrodes 10a. The second small pressure-sensitive layers 21 and 22 are laminated so as to overlap both ends of each of the second electrodes 20a. The first small pressure-sensitive layer 10b completely covers the first small electrode 10a and is formed so as to be separated from the first small pressure-sensitive layer 10b laminated on the adjacent first small electrode 10a. In a plan view, it is preferable that the sizes of the small pressure-sensitive layers are the same. Also, the pair of second small pressure-sensitive layers 21 and 22 may be separated from each other (FIG. 2), but instead of the pair of second small pressure-sensitive layers 21 and 22, one second small pressure-sensitive layer may be provided so as to cover the second electrode 20a.

[0024] The thickness of the small pressure-sensitive layer is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less. When the small pressure-sensitive layer is less than 1 μm, it becomes difficult to sufficiently cover the electrodes, and the upper and lower electrodes conduct without passing through the small pressure-sensitive layer, resulting in poor sensor operation. When the small pressure-sensitive layer exceeds 100 μm, the deformation in response to the change in the pressing force becomes dull, or the time until the pressing force is evenly transmitted to all of the small pressure-sensitive layer increases, resulting in a decrease in the detection accuracy of the pressure and shear force. Also, from the perspective of thinning, the first small electrode 10a, the first small pressure-sensitive layer 10b, the second electrode 20a, and the second small pressure-sensitive layer 21 (or the second small pressure-sensitive layer 22) are preferably formed to have a total thickness of 260 μm or less.

[0025] Since the tactile sensor 100 according to this embodiment detects the pressure and shear force based on the change in the resistance value between the opposing electrodes, the small pressure-sensitive layer is formed of a conductive material. However, it is necessary to use a material having a higher resistivity than that of the electrodes. The resistivity of the small pressure-sensitive layer is preferably 1.0×10 -1 Ω·cm or more and 1.0×10 6 Ωcm or less. In this case, the change amount of the conduction resistance value with respect to the change in the pressing force becomes suitable, and the detection accuracy of the tactile sensor 100 becomes good.

[0026] Also, the tactile sensor 100 can detect the input pressing force by the change in the contact resistance of the contact surface between the first pressure-sensitive element 10 and the second pressure-sensitive element 20 due to the input pressing force. When the pressing force is input, the upper and lower small pressure-sensitive layers come into contact with each other, and the unevenness on the surface is slightly deformed and the contact area increases. Then, since the resistance value changes according to the change in the contact area, the input pressing force can be detected. In this case, it is preferable to use a material that deforms in response to the pressing force for the small pressure-sensitive layer. For example, conductive carbon or conductive nanocarbon can be used. As a method of forming unevenness on the surface of the small pressure-sensitive layer, for example, a method of printing and forming conductive carbon ink using screen printing can be used. Also, unevenness on the order of several μm may be formed on the surface of each small pressure-sensitive layer to make the change in the contact area prominent and make it easier to detect the change in the resistance value.

[0027] Further, the tactile sensor 100 may detect the input pressing force based on the change in the resistance value between the upper and lower small pressure-sensitive layers that occurs with the change in the thickness of the small pressure-sensitive layer caused by the input pressing force. In this case, it is preferable to use a material having a piezoresistive effect in which the resistivity changes due to deformation for the small pressure-sensitive layer. For example, conductive polymers such as polyethylene dioxythiophene, polyaniline, and polypyrrole, carbon paste using graphite or carbon nanotubes, and materials obtained by mixing these with an adjuster such as a medium to adjust the resistivity can be used, and can be formed using known printing methods such as inkjet printing, screen printing, and offset printing, or known coating methods such as spray coating. Further, it may be formed entirely using a vapor deposition method such as a vacuum evaporation method, a sputtering method, a thermal chemical vapor deposition method, or a plasma chemical vapor deposition method and then formed by an etching method. In this case, it can also be formed by forming a film of the material only at a predetermined position using a metal mask.

[0028] The resistivity of the small pressure-sensitive layer is preferably adjusted according to the magnitude of the assumed pressing force. When the assumed pressing force is large, it is preferable to select a material with a gentle change in resistivity, and when the assumed stress is small, it is preferable to select a material with a steep change in resistivity.

[0029] (Connection layer) The connection layer 5 is provided between the first base material 1 and the second base material 2 so as to surround all the first pressure-sensitive elements 10 and the second pressure-sensitive elements 20, and connects the first base material 1 and the second base material 2. The thickness of the connection layer 5 is preferably less than the total thickness of the first pressure-sensitive element 10 and the second pressure-sensitive element 20 (see FIG. 5). Further, there is no particular limitation on the material of the connection layer 5 as long as it has good adhesion to the base material. For example, adhesives such as rubber-based, acrylic-based, and silicone-based adhesives are preferably used. Further, a double-sided tape or the like may be used as the connection layer 5.

[0030] The connection layer 5 is preferably in an annular shape as shown in FIG. 1, centered on the center of the detection region (corresponding to the center of the third detection element O). When the center of the annular connection layer 5 coincides with the center of the detection region, the distances between the detection elements (the first detection elements X1, X2 and the second detection elements Y1, Y2) contributing to the shear force detection and the connection layer 5 are all equal. In this case, the repulsive force of the connection layer 5 when a shear force is applied becomes constant regardless of the direction of the shear force, and the dependence on the application direction of the shear force is reduced, so the detection accuracy is further improved. Also, from the viewpoint of detection accuracy, the connection layer 5 preferably has a radius larger than that of the detection region. Note that the connection layer 5 is not limited to an annular shape and may be square.

[0031] As a method for forming the connection layer 5, for example, in the case of a printing method, an inkjet printing method, a screen printing method, or an offset printing method can be used. Also, it may be formed by attaching a double-sided tape processed into a desired shape to the formation position of the connection layer 5. The double-sided tape is preferably used when it is not desired to apply an excessive heat load to the base material or when it is desired to avoid uneven adhesion due to printing variations.

[0032] (Wiring) Referring further to FIG. 4, the wiring structure according to the present embodiment will be described. FIG. 4 is a schematic circuit diagram of the tactile sensor according to the embodiment. The wiring in the present embodiment includes a plurality of wirings provided on one surface of the first base material 1 and connected to the first detection element X1 and the first detection element X2, a wiring connected to the second detection element Y1 and the second detection element Y2, and a wiring connected to the third detection element O. Also, the wiring connected to the first detection element X1 and the first detection element X2 has a portion that outputs the intermediate potential of the first detection element, and the wiring connected to the second detection element Y1 and the second detection element Y2 has a portion that outputs the intermediate potential of the second detection element. Note that "fixed R" shown in FIG. 4 represents a fixed resistor.

[0033] Here, for the purpose of comparing with the wiring structure of the tactile sensor 100 according to the present embodiment, as a reference example, a wiring structure of a tactile sensor generally considered when there are five pressure-sensitive elements on one base material will be described. FIG. 12 is a schematic diagram of the first base material side of the tactile sensor according to the reference example, and FIG. 13 is a schematic circuit diagram of the tactile sensor according to the reference example. When the number of pressure-sensitive elements is five as in the present embodiment, as shown in FIGS. 12 and 13, one output wiring (X, Y, Z) is connected to each of the first detection element X1, the first detection element X2, the second detection element Y1, the second detection element Y2, and the third detection element O. Hereinafter, such a wiring structure in which one output wiring is provided for one detection element is referred to as "one active wiring". In one active wiring, each output wiring outputs the voltage of the detection element connected thereto.

[0034] On the other hand, in the wiring structure according to the present embodiment, as shown in FIGS. 2(a) and 4, output wirings (corresponding to the first output wiring X and the second output wiring Y described later, respectively) are provided between the first detection element X1 and the first detection element X2, and between the second detection element Y1 and the second detection element Y2. Hereinafter, such a wiring structure in which one output wiring is provided between two pairs of detection elements is referred to as "two active wirings". In two active wirings, the first output wiring X can output the potential between the first detection element X1 and the first detection element X2, and the second output wiring Y can output the potential between the second detection element Y1 and the second detection element Y2. Thus, in the present embodiment, it is characterized in that two active wirings are adopted for the detection elements that detect the shearing force.

[0035] Also, in the present embodiment, as shown in FIG. 2(a), the power supply wiring COM is commonly connected to the divided elements 11 of the first detection element X2, the divided elements 11 of the second detection element Y2, and the divided elements 11 of the third detection element O. The first ground wiring Gx is connected to the divided elements 11 constituting the first detection element X1. The first output wiring X is connected to the divided elements 12 of the first detection element X1 and the divided elements 12 of the first detection element X2. The second ground wiring Gy is connected to the divided elements 11 of the second detection element Y1. The second output wiring Y is connected to the divided elements 12 of the second detection element Y1 and the divided elements 12 of the second detection element Y2. The third output wiring Z is connected to the divided elements 12 of the third detection element O. At this time, within the region surrounded by the wirings (a part of the power supply wiring COM, the first ground wiring Gx, and the first output wiring X) connected to the first detection elements X1 and X2, the wirings (a part of the power supply wiring COM, the second ground wiring Gy, and the second output wiring Y) connected to the second detection elements Y1 and Y2 and the wirings (a part of the power supply wiring COM and the third output wiring Z) connected to the third detection element O are designed to be arranged. By adopting such a wiring design, the wirings connected to the first detection elements X1 and X2, which are arranged on the outermost side when viewed from the direction in which the wirings of the first base material 1 extend (the Y-axis direction in FIG. 2(a)), are arranged on the outermost side, and the other wirings (the wirings connected to the second detection elements Y1 and Y2 and the third detection element O, which are arranged inside the first detection elements X1 and X2 when viewed from the direction in which the wirings extend) are housed within that region. Therefore, the wiring structure becomes simple, and the tactile sensor 100 can be miniaturized. When the wiring design does not satisfy the above conditions, as shown in FIG. 14, the wirings are partially dense or a plurality of wirings are arranged outside the first pressure-sensitive element 10, so that the wiring structure becomes complicated and the miniaturization of the tactile sensor is inhibited. In FIG. 14, for the sake of convenience, the small pressure-sensitive layer is omitted from the description.

[0036] Next, when six types of wirings (power supply wiring COM, first ground wiring Gx, second ground wiring Gy, first output wiring X, second output wiring Y, and third output wiring Z) are used as in this embodiment, a more detailed description will be given. As shown in Fig. 2(a), the portion connecting the divided element 12 of the first detection element X1 and the divided element 12 of the first detection element X2 of the first output wiring X is provided so as to pass outside the five first pressure-sensitive elements 10. Further, the second ground wiring Gy, the second output wiring Y, the third output wiring Z, and a part of the power supply wiring COM are located inside the innermost current path (the path passing through the power supply wiring COM, the divided element 11 of the first detection element X2, the fourth detection element X2', and the divided element 12 of the first detection element X2 in sequence and reaching the first ground wiring Gx or the first output wiring X) from the power supply wiring COM to the first ground wiring Gx or the first output wiring X. Also, since the power supply wiring COM is commonly connected to the divided elements 11 of the first detection element X2, the second detection element Y2, and the third detection element O respectively, the wiring has branches, but the branches are formed inside the first detection elements X1, X2 and the second detection elements Y1, Y2. Thereby, since the divided elements 11 of the first detection element X2, the second detection element Y2, and the third detection element O can be connected to each other at the shortest distance, unnecessary wiring routing can be avoided and wiring density can be suppressed. Note that all the wirings (power supply wiring COM, first ground wiring Gx, second ground wiring Gy, first output wiring X, second output wiring Y, third output wiring Z) do not cross each other.

[0037] Also, outside the five first pressure-sensitive elements 10, the power supply wiring COM, the first ground wiring Gx, the first output wiring X, the second ground wiring Gy, the second output wiring Y, and the third output wiring Z are arranged so as to extend parallel to each other and in the same direction, and it is preferable that the power supply wiring COM and the first output wiring X are arranged on both outer sides in the parallel direction. Further, outside the five first pressure-sensitive elements 10, it is preferable that the first output wiring X, the first ground wiring Gx, the second output wiring Y, the second ground wiring Gy, the third output wiring Z, and the power supply wiring COM are arranged in this order.

[0038] (Detection principle) First, the pressure detection of the tactile sensor 100 according to this embodiment will be described. In this embodiment, the pressure can be detected by the third detection element O and the sixth detection element O' facing it.

[0039] FIG. 5 is a partial cross-sectional view of the tactile sensor during pressure measurement. In FIG. 5, the case where the first small electrode 10a is larger than the overlapping portion between the first small electrode 10a and the second electrode 20a is shown, but they may have the same size. When no pressure is applied, the contact area between the third detection element O and the sixth detection element O' is small, or the upper and lower small pressure-sensitive layers are not in contact with each other, so the electrical resistance value between the third detection element O and the sixth detection element O' is large (FIG. 5(a)). By applying the pressure F1, the uneven shape of the surface of the upper and lower small pressure-sensitive layers is slightly deformed, and the contact area increases (FIG. 5(b)). When the contact area increases, the conduction paths between the first small electrode 10a of the third detection element O on the first base material 1 and the second electrode 20a of the sixth detection element O' on the second base material 2 increase, so the electrical resistance value decreases. Therefore, the pressure can be detected based on the electrical resistance value between the third detection element O on the first base material 1 and the sixth detection element O' on the second base material 2. The conversion from the electrical resistance value to the pressure is performed based on the relationship between the pressure obtained in advance as a calibration curve and the resistance value between the third detection element O and the sixth detection element O'.

[0040] Next, the shear force detection of the tactile sensor 100 according to this embodiment will be described. In this embodiment, the shear force in the X-axis direction can be detected by the first detection elements X1, X2 and the fourth detection elements X1', X2' facing them, and the shear force in the Y-axis direction can be detected by the second detection elements Y1, Y2 and the fifth detection elements Y1', Y2' facing them.

[0041] When two active wirings are adopted as in this embodiment, the first output wiring X can output the potential between the first detection elements X1 and X2, and the second output wiring Y can output the potential between the second detection elements Y1 and Y2 (Fig. 4). At this time, when a shearing force is input in the first direction (X-axis direction), the resistance value of either one of the first detection elements X1 and X2 increases and the resistance value of the other decreases. Then, the output changes according to the ratio of the change amounts of the resistance values of the first detection element X1 and the first detection element X2, and the shearing amount can be directly obtained from the output voltage change. Further, when a shearing force is input in the second direction (Y-axis direction), the resistance value of either one of the second detection elements Y1 and Y2 increases and the resistance value of the other decreases, and output becomes possible according to the ratio of the change amounts of the resistance values of the second detection element Y1 and the second detection element Y2, and the shearing amount can be directly obtained from the output voltage change.

[0042] The detection of the shearing force will be described in more detail with reference to Figs. 6 to 8. Fig. 6 is a cross-sectional view of the tactile sensor at the time of measuring the shearing force. Fig. 7 is a diagram for explaining the detection of the shearing force in the X-axis direction. Fig. 8 is a graph showing the relationship between the shearing displacement and the output value in the X-axis direction when two active wirings are adopted. In the shearing displacement of Fig. 7, the positive direction is the right direction on the paper surface in Fig. 1 (positive direction of the X-axis), and the negative direction is the left direction on the paper surface in Fig. 1 (negative direction of the X-axis). Here, the detection of the shearing force in the X-axis direction will be described, but the detection method of the shearing force in the Y-axis direction can also be detected by the same principle.

[0043] The case where no load is applied to the tactile sensor 100 is taken as the initial state, and the resistance values of the first detection elements X1 and X2 at this time are respectively denoted as R1 and R2 (Fig. 7(a)). Note that the output value in this initial state can be appropriately changed according to the application and conditions.

[0044] When only a predetermined pressure is applied to the tactile sensor 100 (Fig. 6(a)), the loads applied to the first detection element X1 and the first detection element X2 are the same (Fig. 7(b)). At this time, if the change amounts of the resistance values from the initial states in the first detection element X1 and the first detection element X2 are ΔR1 and ΔR2 respectively, ΔR1 and ΔR2 are equal. That is, the resistance values of the first detection element X1 and the first detection element X2 are equal (R1 + ΔR1 = R2 + ΔR2), and the output value from the first output wiring X (the potential between the first detection elements X1 and X2) does not change from the initial state (Fig. 8). From this, it is required that the shear displacement is 0 μm. Note that both ΔR1 and ΔR2 are negative values.

[0045] When a shear force is applied in the positive direction of the X-axis (the right direction of the paper surface in Fig. 1) in addition to the pressure to the tactile sensor 100 (Fig. 6(b)), a larger load is applied to the first detection element X2 than to the first detection element X1 (Fig. 7(c)). At this time, if the change amounts from the state of Fig. 7(b) (the state where only pressure is applied) in the first detection element X1 and the first detection element X2 are ΔR1' and ΔR2' respectively, |ΔR1'| = |ΔR2'| (however, ΔR1' is a positive value and ΔR2' is a negative value). Also, the resistance value of the first detection element X1 becomes larger than the resistance value of the first detection element X2 (R1 + ΔR1 > R2 + ΔR2), and the output value from the first output wiring X (the potential between the first detection elements X1 and X2) becomes smaller. Since the output value from the first output wiring X changes from the initial state according to the ratio of the change amounts ΔR1 and ΔR2 of the resistance values of the first detection element X1 and the first detection element X2, the shear force can be obtained from the relationship between the output value and the potential and the shear force acquired in advance as a calibration curve. Thus, when a shear force in the positive direction of the X-axis is applied, the output value decreases from 2.8 V in proportion to the shear displacement (Fig. 8).

[0046] When a shearing force is applied to the tactile sensor 100 in the negative direction of the X-axis (the left direction on the paper surface in FIG. 1) in addition to the pressure, a larger load is applied to the first detection element X1 than to the first detection element X2 (FIG. 7(d)). At this time, if the amounts of change from the state of FIG. 7(b) (the state where only pressure is applied) in the first detection element X1 and the first detection element X2 are ΔR1’ and ΔR2’ respectively, then |ΔR1’| = |ΔR2’| (however, ΔR1’ is a negative value and ΔR2’ is a positive value). Also, the resistance value of the first detection element X1 becomes smaller than the resistance value of the first detection element X2 (R1 + ΔR1 < R2 + ΔR2), and the output value from the first output wiring X (the potential between the first detection elements X1 and X2) becomes larger. At this time, since the output value from the first output wiring X changes from the initial state according to the ratio of the change amounts ΔR1 and ΔR2 of the resistance values of the first detection element X1 and the first detection element X2, the shearing force can be obtained from the relationship between the output value and the potential and the shearing force that was previously obtained as a calibration curve. Thus, when a shearing force in the negative direction of the X-axis is applied, the output value increases from 2.8V in proportion to the shearing displacement (FIG. 8).

[0047] FIG. 9 is a graph showing the relationship between the shearing displacement and the output value in the X-axis direction when one active wiring is adopted. FIG. 10 is a graph showing the relationship between the shearing displacement and the output value in one active wiring and two active wirings. In the case of two active wirings, since the change amounts ΔR1’ and ΔR2’ of the resistance values of the first detection element X1 and the first detection element X2 change with opposite signs to each other, for example, when the absolute values of the change amounts ΔR1’ and ΔR2’ are the same, the output change becomes twice as large as when taking the output from each of the first detection element X1 and the first detection element X2 as in the case of one active wiring, and the sensitivity is improved. On the other hand, when simply adopting one active wiring, since the direction and magnitude of the applied shearing force are detected based on the outputs of the first detection element X1 and the first detection element X2 respectively, the sensitivity is lower compared to the case of two active wirings (FIGS. 9 and 10).

[0048] As described above, the tactile sensor 100 according to the present embodiment employs two active wirings. Therefore, it is possible to provide a tactile sensor with higher sensitivity than when a general single active wiring is employed. Further, in the wirings connected to the first detection elements X1 and X2, the wirings connected to the second detection elements Y1 and Y2, and the wiring connected to the third detection element O, within the region surrounded by the wiring connected to the first detection elements X1 and X2, the wiring connected to the second detection elements Y1 and Y2 and the wiring connected to the third detection element O are provided. Therefore, even when two active wirings are employed, it is possible to provide a tactile sensor having a simple wiring structure and being advantageous for miniaturization. Further, in this wiring structure, the number of wirings passing between adjacent electrodes can be reduced (to within one in the present embodiment). Therefore, the influence on the detection sensitivity of the tactile sensor is small.

[0049] <Second Embodiment> FIG. 11 is a plan view of the first base material side of the tactile sensor according to the second embodiment of the present invention. In the tactile sensor 100 in the first embodiment, there are six types of wirings arranged on the first base material 1 (power supply wiring COM, first ground wiring Gx, second ground wiring Gy, first output wiring X, second output wiring Y, third output wiring Z). However, in the tactile sensor according to the second embodiment, the wirings are five types: power supply wiring COM, ground wiring G, first output wiring X, second output wiring Y, and third output wiring Z. The ground wiring G can be regarded as a wiring that combines the first ground wiring Gx and the second ground wiring Gy in the tactile sensor 100.

[0050] More specifically, the wirings include a power supply wiring COM connected to one of the divided elements 11 of the first detection element X2, the divided elements 11 of the second detection element Y2, and the divided elements 11 of the third detection element O, a ground wiring G connected to the divided elements 11 of the first detection element X1 and the divided elements 12 of the second detection element Y1, a first output wiring X connected to the divided elements 12 of the first detection element X1 and the divided elements 12 of the first detection element X2, a second output wiring Y connected to the divided elements 11 and 12 of the second detection element Y1, and a third output wiring Z connected to the divided elements 12 of the third detection element O.

[0051] And, among the first output wirings X, the portion connecting at least the divided element 12 of the first detection element X1 and the divided element 12 of the first detection element X2 is provided so as to pass outside the five first pressure-sensitive elements 10, and a part of the ground wiring G, the second output wiring Y, the third output wiring Z, and a part of the power supply wiring COM are provided inside the innermost current path leading from the power supply wiring COM to the ground wiring G or the first output wiring X. Further, since the power supply wiring COM is commonly connected to the divided elements 11 of the first detection element X2, the second detection element Y2, and the third detection element O respectively, the wiring has branches, but the branches are formed inside the first detection elements X1, X2 and the second detection elements Y1, Y2. Thereby, since the divided elements 11 of the first detection element X2, the second detection element Y2, and the third detection element O can be connected to each other at the shortest distance, useless wiring routing can be avoided, and wiring density can be suppressed. Note that all the wirings (power supply wiring COM, ground wiring G, first output wiring X, second output wiring Y, third output wiring Z) do not cross each other.

[0052] Note that when the wiring design does not satisfy the above conditions, as shown in FIG. 15, the wiring is partially dense or a plurality of wirings are arranged outside the first pressure-sensitive element 10, so that the wiring structure becomes complicated and miniaturization of the tactile sensor is hindered. In FIG. 15, the small pressure-sensitive layer is omitted for convenience of description.

[0053] Also, outside the five first pressure-sensitive elements 10, the power supply wiring COM, the ground wiring G, the second output wiring Y, and the third output wiring Z are arranged so as to extend parallel to each other and in the same direction, and it is preferable that the power supply wiring COM and the first output wiring X are arranged on both outer sides in the parallel direction. Further, outside the five first pressure-sensitive elements 10, it is preferable that the first output wiring X, the ground wiring G, the second output wiring Y, the third output wiring Z, and the power supply wiring COM are arranged in this order.

Industrial Applicability

[0054] The present invention can be applied to a tactile sensor capable of detecting pressure and shear force.

Explanation of Signs

[0055] 1: First base material 2: Second base material 5: Connection layer 10: First pressure-sensitive element 11: Divided element 12: Divided element 20: Second pressure-sensitive element 100: Tactile sensor COM: Power supply wiring G: Ground wiring Gx: First ground wiring Gy: Second ground wiring O: Third detection element O': Sixth detection element X: First output wiring X1: First detection element X1': Fourth detection element X2: First detection element X2': Fourth detection element Y: Second output wiring Y1: Second detection element Y1': Fifth detection element Y2: Second detection element Y2': Fifth detection element Z: Third output wiring

Claims

1. a first substrate, a second substrate facing one surface of the first substrate, five first pressure-sensitive elements provided on the one surface of the first substrate, five second pressure-sensitive elements provided on the surface of the second substrate facing the first substrate and facing each of the five first pressure-sensitive elements, a plurality of wirings provided on the one surface of the first substrate, the first pressure-sensitive element and the second pressure-sensitive element are elements whose resistance value changes in response to a pressure change, the five first pressure-sensitive elements, two first detection elements aligned in a predetermined first direction, two second detection elements aligned in a second direction orthogonal to the first direction, including one third detection element, the two first detection elements are arranged at equal intervals around the third detection element, and the two second detection elements are arranged at equal intervals around the third detection element, the plurality of wirings include a wiring connected to the two first detection elements, a wiring connected to the two second detection elements, and a wiring connected to the third detection element, the wiring connected to the two first detection elements has a portion that outputs the potential in the middle of the two first detection elements, and the wiring connected to the two second detection elements has a portion that outputs the potential in the middle of the two second detection elements, A tactile sensor in which a wiring connected to the two second detection elements and a wiring connected to the third detection element are provided inside a region surrounded by the wiring connected to the two first detection elements.

2. Each of the first detection element, the second detection element, and the third detection element constituting the first pressure-sensitive element is composed of a pair of divided elements arranged at a predetermined interval, each of the second pressure-sensitive elements overlaps both of a pair of divided elements arranged at opposing positions in a plan view, the plurality of wirings, a power supply wiring connected to one of the divided elements constituting one of the first detection elements, one of the divided elements constituting one of the second detection elements, and one of the divided elements constituting the third detection element, a first ground wiring connected to one of the divided elements constituting the other of the first detection elements, a first output wiring connected to the other of the divided elements constituting the one of the first detection elements and the other of the divided elements constituting the other of the first detection elements, a second ground wiring connected to one of the divided elements constituting the other of the second detection elements, A second output wiring connected to the other of the split elements constituting one of the second detection elements and the other of the split elements constituting the other of the second detection elements; A third output wiring connected to the other of the split elements constituting the third detection element; Among the first output wirings, at least the portion connecting the other of the split elements constituting one of the first detection elements and the other of the split elements constituting the other of the first detection elements is provided so as to pass outside the five first pressure-sensitive elements; The second ground wiring, the second output wiring, the third output wiring, and a part of the power supply wiring are provided inside the innermost current path extending from the power supply wiring to the first ground wiring or the first output wiring; The tactile sensor according to claim 1, wherein the power supply wiring, the first ground wiring, the first output wiring, the second ground wiring, the second output wiring, and the third output wiring do not cross each other.

3. The tactile sensor according to claim 2, wherein the power supply wiring branches inside the first detection element and the second detection element.

4. Outside the five first pressure-sensitive elements, the power supply wiring, the first ground wiring, the first output wiring, the second ground wiring, the second output wiring, and the third output wiring are arranged so as to extend parallel to each other and in the same direction, and the power supply wiring and the first output wiring are arranged on both outer sides in the parallel direction. The tactile sensor according to claim 2.

5. The tactile sensor according to claim 4, wherein the first output wiring, the first ground wiring, the second output wiring, the second ground wiring, the third output wiring, and the power supply wiring are arranged in this order outside the five first pressure-sensitive elements.

6. Each of the first detection element, the second detection element, and the third detection element constituting the first pressure-sensitive element is composed of a pair of split elements arranged at a predetermined interval; Each of the second pressure-sensitive elements overlaps with both of a pair of split elements arranged at opposing positions in a plan view; The plurality of wirings are A power supply wiring connected to one of the split elements constituting one of the first detection elements, one of the split elements constituting one of the second detection elements, and one of the split elements constituting the third detection element; A ground wiring connected to one of the split elements constituting the other of the first detection elements and one of the split elements constituting the other of the second detection elements; A first output wiring connected to the other of the divided elements constituting one of the first detection elements and the other of the divided elements constituting the other of the first detection elements; A second output wiring connected to the other of the divided elements constituting one of the second detection elements and the other of the divided elements constituting the other of the second detection elements; A third output wiring connected to the other of the divided elements constituting the third detection element, Among the first output wiring, at least the portion connecting the other of the divided elements constituting one of the first detection elements and the other of the divided elements constituting the other of the first detection elements is provided so as to pass outside the five first pressure-sensitive elements; A part of the ground wiring, the second output wiring, the third output wiring, and a part of the power supply wiring are provided inside the innermost current path extending from the power supply wiring to the ground wiring or the first output wiring; The tactile sensor according to claim 1, wherein the power supply wiring, the ground wiring, the first output wiring, the second output wiring, and the third output wiring do not cross each other. **Claim 7** The tactile sensor according to claim 6, wherein the power supply wiring branches inside the first detection element and the second detection element. **Claim 8** Outside the five first pressure-sensitive elements, the power supply wiring, the ground wiring, the first output wiring, the second output wiring, and the third output wiring are arranged to extend parallel to each other and in the same direction, and the power supply wiring and the first output wiring are arranged on both outer sides in the parallel direction. The tactile sensor according to claim 6. **Claim 9** Outside the five first pressure-sensitive elements, the first output wiring, the ground wiring, the second output wiring, the third output wiring, and the power supply wiring are arranged in this order. The tactile sensor according to claim 6. **Claim 10** The tactile sensor according to claim 2 or 6, wherein the total thickness of the first base material and the second base material is 200 μm or less. **Claim 11** The first output wiring outputs the potential between the two first detection elements. The second output wiring outputs the potential between the two second detection elements. When a shearing force is applied in the first direction, the resistance value of either one of the two first detection elements increases and the resistance value of the other decreases. The tactile sensor according to claim 2 or 6, wherein when a shearing force is applied in the second direction, the resistance value of either one of the two second detection elements increases and the resistance value of the other decreases.

12. The tactile sensor according to claim 2 or 6, wherein the first substrate and the second substrate are connected by a connection layer formed so as to surround the five first pressure-sensitive elements and the five second pressure-sensitive elements.

Images