Stretchable device

Abstract

According to the present invention, a stretchable substrate of a stretchable device comprises a resin base material and an array layer layered in that order in the thickness direction of said substrate. The stretchable substrate is divided into a plurality of body parts and a plurality of hinge parts. The array layer includes a strain detection circuit. The strain detection circuit includes: a strain gauge; a first resistance part, a first end of which is connected to a second end of the strain gauge; a second resistance part, a first end of which is connected to a first end of the strain gauge; and a third resistance part, a first end of which is connected to a second end of the second resistance part and a second end of which is connected to a second end of the first resistance part. The body parts are composed of an array layer and include a first surface facing a direction opposing the resin base material, and a second surface composed of a resin base material and facing a direction opposing the array layer. A heat dissipation opening that opens toward the outer side in the thickness direction is formed on at least one of the first surface and the second surface.

Description

Stretchable Device

[0001] The present invention relates to a stretchable device.

[0002] The stretchable device has a stretchable substrate that is excellent in elasticity and flexibility. The stretchable substrate includes a resin base material and an array layer provided along the resin base material. The stretchable substrate has body portions arranged in a matrix and hinge portions that connect the body portions to each other. The hinge portion in Patent Document 1 has multiple arc portions and a meandering shape. When a tensile load, for example, acts on the stretchable substrate, the arc portions of the hinge portion expand. As a result, the body portions connected to both ends of the hinge portion separate from each other, and the stretchable substrate elongates.

[0003] JP 2020-202208 A

[0004] In recent years, in order to detect the load acting on a stretchable device, studies have been conducted on installing strain gauges in the hinge section to detect the strain (deformation) of the hinge section. However, because the resistance value of strain gauges changes with temperature changes, the signal output from the strain gauge may contain noise. As a result, it may not be possible to accurately detect the strain of the hinge section.

[0005] An object of the present invention is to provide a stretchable device that can accurately detect the amount of strain at a hinge portion.

[0006] A stretchable device according to one aspect of the present disclosure includes a plate-shaped stretchable substrate having a plurality of lightening holes formed therethrough in the thickness direction. The stretchable substrate includes a resin base material and an array layer laminated in this order in the thickness direction. When viewed from the thickness direction, the stretchable substrate is divided into a plurality of body portions and a plurality of hinge portions connecting the body portions. The array layer includes a strain detection circuit that detects the amount of strain in the hinge portions. The strain detection circuit includes a strain gauge extending from the body portion to the hinge portion and folding back to the body portion, a first resistor disposed in the body portion where both ends of the strain gauge are located and having one end connected to the other end of the strain gauge, a second resistor disposed in the body portion where both ends of the strain gauge are located and having one end connected to one end of the strain gauge, and a third resistor disposed in the body portion where both ends of the strain gauge are located and having one end connected to the other end of the second resistor and the other end connected to the other end of the first resistor. The body portion has a first surface formed by the array layer and facing away from the resin substrate, and a second surface formed by the resin substrate and facing away from the array layer. At least one of the first surface and the second surface has a heat dissipation opening that opens outward in the thickness direction.

[0007] FIG. 1 is a plan view of a stretchable device according to a first embodiment. FIG. 2 is a schematic diagram illustrating a cross section of the stretchable device according to the first embodiment, specifically a cross section taken along line II-II in FIG. 3. FIG. 3 is an enlarged view of a portion of the stretchable substrate according to the first embodiment that is included in a detection region. FIG. 4 is an enlarged view of a vertical hinge portion according to the first embodiment. FIG. 5 is an enlarged view of the vertical hinge portion according to the first embodiment when a tensile load in a first direction is applied to the vertical hinge portion. FIG. 6 is a plan view schematically illustrating each component of a strain detection circuit disposed in a body portion according to the first embodiment. FIG. 7 is a schematic diagram illustrating a Wheatstone bridge circuit according to the first embodiment. FIG. 8 is a plan view of the body portion of the stretchable substrate as viewed from the first thickness direction. FIG. 9 is a cross-sectional view taken along line IX-IX. FIG. 10 is a cross-sectional view of a body portion according to a first modification. FIG. 11 is a cross-sectional view of a body portion according to a second modification. FIG. 12 is a cross-sectional view of a body portion according to a third modification. FIG. 13 is a cross-sectional view of a body portion according to a fourth modification. Fig. 14 is a cross-sectional view of a body portion of Modification 5. Fig. 15 is a plan view of a body portion of Modification 6 as viewed from the second thickness direction.

[0008] Modes (embodiments) for carrying out the present disclosure will be described in detail with reference to the drawings. The invention of the present disclosure is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the components described below can be combined as appropriate. Note that the disclosure is merely an example, and any appropriate modifications that a person skilled in the art can easily conceive while maintaining the gist of the invention are naturally included within the scope of the present invention. For clarity of explanation, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to the actual embodiment. However, these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each figure, components similar to those described above with reference to the previous figures are designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0009] Furthermore, in this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case in which another structure is placed above a certain structure via yet another structure.

[0010] (Embodiment 1) Fig. 1 is a plan view of a stretchable device according to embodiment 1. As shown in Fig. 1, the stretchable device 100 is formed in a flat plate shape. The stretchable device 100 has a front surface 1 and a back surface 2 (not shown in Fig. 1; see Fig. 2) that face in opposite directions. Hereinafter, the directions parallel to each of the front surface 1 and the back surface 2 will be referred to as planar directions.

[0011] Fig. 2 is a diagram schematically illustrating a cross section of the stretchable device according to the first embodiment, and more specifically, a cross section taken along line II-II in Fig. 3. As shown in Fig. 2, the stretchable device 100 has a first stretchable resin 60, a stretchable substrate 10, and a second stretchable resin 70, which are layered in this order. Hereinafter, the direction in which the first stretchable resin 60, the stretchable substrate 10, and the second stretchable resin 70 are arranged will be referred to as the thickness direction. Therefore, the stretchable substrate 10 is sandwiched between a pair of stretchable resins (the first stretchable resin 60 and the second stretchable resin 70) on both sides in the thickness direction.

[0012] Hereinafter, with regard to the thickness direction, the direction in which the second elastic resin 70 is arranged as viewed from the first elastic resin 60 will be referred to as the first thickness direction Z1, and the direction opposite to the first thickness direction Z1 will be referred to as the second thickness direction Z2. Also, viewing the stretchable device 100 from the first thickness direction Z1 will be referred to as a planar view.

[0013] 1, the stretchable device 100 is formed into a rectangular (quadrilateral) shape in a plan view. Therefore, the surface 1 of the stretchable device 100 has a pair of long sides 3 and a pair of short sides 4. Hereinafter, the direction parallel to the planar direction and parallel to the long sides 3 will be referred to as the first direction X, and the direction parallel to the short sides 4 will be referred to as the second direction Y.

[0014] In a plan view, the stretchable device 100 is divided into a detection area 5 that detects a load and a non-detection area 6 other than the detection area 5. The detection area 5 is located in the center of the stretchable device 100 and is formed into a rectangle (quadrilateral) in a plan view. The non-detection area 6 is formed into a quadrangular frame in a plan view, and the detection area 5 is located inside it. Note that a boundary line L1 is drawn in FIG. 1 to make the boundary between the detection area 5 and the non-detection area 6 easier to understand.

[0015] 2, the first elastic resin 60 and the second elastic resin 70 have insulating properties, elasticity, and flexibility. Examples of resins used as the first elastic resin 60 and the second elastic resin 70 include acrylic elastomers. Note that the first elastic resin 60 and the second elastic resin 70 of the present disclosure are not limited to acrylic elastomers, and may be acrylic resins, epoxy resins, urethane resins, or the like, and are not particularly limited.

[0016] The first elastic resin 60 and the second elastic resin 70 are formed in a plate shape and extend in a planar direction. The surface of the first elastic resin 60 in the second thickness direction Z2 constitutes the back surface 2 of the stretchable device 100. The first elastic resin 60 has an opposing surface 61 that faces the first thickness direction Z1 and faces the stretchable substrate 10.

[0017] The surface of the second stretchable resin 70 in the first thickness direction Z1 constitutes the surface 1 of the stretchable device 100. The second stretchable resin 70 faces the second thickness direction Z2 and has an opposing surface 71 that faces the stretchable substrate 10. In addition, a frame portion 72 that protrudes in the second thickness direction Z2 beyond the opposing surface 71 is provided on the edge of the second stretchable resin 70.

[0018] The frame portion 72 is formed in a ring shape in a plan view, and surrounds the outer periphery of the stretchable substrate 10. A surface 72a of the frame portion 72 in the second thickness direction Z2 is adhered to the opposing surface 61 of the first stretchable resin 60. As a result, the first stretchable resin 60 and the second stretchable resin 70 cooperate with each other to form a housing that houses the stretchable substrate 10.

[0019] The stretchable substrate 10 is provided with a plurality of lightening holes 19 penetrating in the thickness direction. The second stretchable resin 70 has a plurality of protrusions 73 that protrude from the opposing surface 71 in the second thickness direction Z2 and are disposed in the lightening holes 19.

[0020] Although the lightening hole 19 in this embodiment is filled with the second elastic resin 70 (protrusion 73), in the present disclosure it may be filled with the first elastic resin 60. Alternatively, the lightening hole 19 may be filled with both the first elastic resin 60 and the second elastic resin 70. Alternatively, the lightening hole 19 may be filled with a resin other than the first elastic resin 60 and the second elastic resin 70. Alternatively, the lightening hole 19 may be empty, leaving a space.

[0021] 3 is an enlarged view of a portion of the stretchable substrate 10 included in the detection area 5 in embodiment 1. As shown in Fig. 3, when viewed in plan, the portion of the stretchable substrate 10 included in the detection area 5 is divided into a plurality of body portions 11 in the detection area 5 and a plurality of hinge portions 12 that extend in a serpentine manner in the planar direction.

[0022] 4 is an enlarged view of the vertical hinge portion of the first embodiment. As shown in FIG. 4, the body portion 11 has an octagonal shape in a plan view. The multiple body portions 11 are arranged in the first direction X and the second direction Y and are spaced apart from one another. Note that the shape of the body portion 11 in a plan view according to the present disclosure is not limited to an octagonal shape, and may be a circle or another polygonal shape.

[0023] 3, the hinge portion 12 connects adjacent body portions 11. There are two types of hinge portions 12: a vertical hinge portion 12A extending in the first direction X, and a horizontal hinge portion 12B extending in the second direction Y.

[0024] Next, details of the hinge portion 12 will be described. When the horizontal hinge portion 12B is rotated by 90 degrees, it has the same shape as the vertical hinge portion 12A. Therefore, the vertical hinge portion 12A will be described below as a representative example.

[0025] As shown in Fig. 4, the vertical hinge portion 12A has four bent portions 13 and extends in a serpentine manner in the first direction X. In this embodiment, each bent portion 13 has an arc shape. Note that the bent portions of the present disclosure may be formed in an angular shape instead of an arc shape. Furthermore, the number of bent portions is not limited to four.

[0026] The four bent portions 13 are a first arc portion 14, a second arc portion 15, a third arc portion 16, and a fourth arc portion 17, which are arranged in this order in the first direction X. The first arc portion 14 and the fourth arc portion 17 are quadrant-shaped and bent at 90 degrees. The second arc portion 15 and the third arc portion 16 are semicircular-shaped and bent at 180 degrees.

[0027] Fig. 5 is an enlarged view of the vertical hinge portion of the first embodiment when a tensile load in a first direction acts on the vertical hinge portion. As shown in Fig. 5, when a tensile load in the first direction X (see arrow W in Fig. 5) acts on the vertical hinge portion 12A, the first arc portion 14, the second arc portion 15, the third arc portion 16, and the fourth arc portion 17 are deformed so that their curvatures become smaller. As a result, the distance from one end to the other end of the vertical hinge portion 12A increases, and the body portions 11 are separated from each other.

[0028] Furthermore, although not shown, when a compressive load in the first direction X acts on the vertical hinge portion 12A, the first arc portion 14, the second arc portion 15, the third arc portion 16, and the fourth arc portion 17 are deformed so as to increase their curvatures, respectively, and as a result, the distance from one end to the other end of the vertical hinge portion 12A decreases, and the body portions 11 move closer to each other.

[0029] Although not specifically shown, the portion of the stretchable substrate 10 included in the non-detection region 6 has a frame shape along the non-detection region 6 when viewed in plan. The portion of the stretchable substrate 10 included in the non-detection region 6 of the present disclosure may have a lightening hole 19 formed therein, and may have a frame shape formed by a plurality of body portions 11 and a plurality of hinge portions 12.

[0030] 2, the stretchable substrate 10 has a resin substrate 20 and an array layer 21. The resin substrate 20 is a base material for producing the array layer 21, and has stretchability, flexibility, and insulating properties. The resin substrate 20 is made of a resin material such as polyimide.

[0031] The array layer 21 is provided on a surface of the resin substrate 20 in the first thickness direction Z1. The array layer 21 has a plurality of insulating layers (see the first insulating layer 23, the second insulating layer 24, and the third insulating layer 25 in FIG. 9 ) stacked in the thickness direction, and an electrical circuit (strain detection circuit) whose insulation from the outside is ensured by the plurality of insulating layers. The insulating layer may be, for example, an organic layer such as a silicon oxide film or a resin layer made of polyimide, and is not particularly limited. Next, the strain detection circuit included in the array layer 21 will be described in detail.

[0032] 6 is a plan view schematically illustrating each component of the strain detection circuit arranged in the body portion of embodiment 1. The strain detection circuit included in the array layer 21 is a circuit for detecting a load input to the stretchable device 100. As shown in FIG. 6, the strain detection circuit includes a strain gauge 30 (see FIG. 4 for details), a first resistor 41, a second resistor 42, a third resistor 43, a first potential line 44, a second potential line 45, a transistor 46, a gate line 47, a first detection line 48, and a second detection line 49.

[0033] As shown in FIG. 4 , the strain gauge 30 extends from the body portion 11 to the hinge portion 12, then folds back and returns to the body portion 11. Therefore, the strain gauge 30 includes a first strain gauge 31 and a second strain gauge 32 extending along the hinge portion 12, and a connection portion 33 connecting the ends of the first strain gauge 31 and the second strain gauge 32. This strain gauge 30 is twice as long as a conventional strain gauge (a strain gauge having the same length as the first strain gauge 31). This allows it to detect a larger amount of strain and has high detection sensitivity. Furthermore, as shown in FIG. 6 , the start end 31 a and end end 32 a of the strain gauge 30 are located in the body portion 11.

[0034] In this embodiment, the strain gauges 30 are not provided in all hinge portions 12. The strain gauges 30 are provided only in the vertical hinge portions 12A. In the present disclosure, the strain gauges 30 may be provided only in the horizontal hinge portions 12B that overlap the detection area 5, instead of in the vertical hinge portions 12A that overlap the detection area 5, or may be provided in all hinge portions 12 that overlap the detection area 5; there are no particular limitations.

[0035] 6, the first resistor 41, the second resistor 42, and the third resistor 43 are each disposed in the body portion 11 where both ends (starting end 31a and ending end 32a) of the strain gauge 30 are disposed. The resistance values ​​of the first resistor 41, the second resistor 42, and the third resistor 43 will be described later. One end of the first resistor 41 is connected to the ending end 32a of the strain gauge 30. Hereinafter, the connection point between the ending end 32a of the strain gauge 30 and one end of the first resistor 41 will be referred to as a first intermediate point P2.

[0036] One end of the second resistor 42 is connected to the starting end 31a of the strain gauge 30. Hereinafter, the connection point between the starting end 31ab of the strain gauge 30 and one end of the second resistor 42 will be referred to as the first connection point P1. One end of the third resistor 43 is connected to the other end of the second resistor 42. Hereinafter, the connection point between the other end of the second resistor 42 and one end of the third resistor 43 will be referred to as the second intermediate point P4. Furthermore, the other end of the third resistor 43 is connected to the other end of the first resistor 41. Hereinafter, the connection point between the other end of the first resistor 41 and the other end of the third resistor 43 will be referred to as the second connection point P3.

[0037] 3, the first potential line 44 and the second potential line 45 are each disposed across a plurality of vertical hinge portions 12A and a plurality of body portions 11, and extend in the first direction X. Note that in Fig. 3, the first potential line 44 and the second potential line 45 extending in the first direction X are collectively illustrated as a single line. Furthermore, the first potential line 44 and the second potential line 45 are provided for each of the body portions 11 and vertical hinge portions 12A arranged in the second direction Y, but Fig. 3 illustrates only some of the plurality of first potential lines 44 and second potential lines 45.

[0038] 6, the first potential line 44 is connected to a first connection point P1 via a switch element (transistor 46) in the body portion 11. Therefore, when the transistor 46 is closed, the first connection point P1 is applied to the first potential line 44 and becomes a first potential V1. The first potential line 44 is connected to the first connection points P1 of each of the body portions 11 arranged in the first direction X1.

[0039] 6 , the second potential line 45 is connected to the second connection point P3 in the body portion 11. Therefore, the second connection point P3 is applied with the second potential line 45 and becomes the second potential V2. In this embodiment, the second potential V2 is 0 V. The second potential line 45 is connected to the second connection point P3 of each of the body portions 11 arranged in the first direction X1.

[0040] 3, the gate line 47 is disposed across multiple horizontal hinge portions 12B and multiple body portions 11, and extends in the second direction Y. As shown in Fig. 6, the gate line 47 is connected to the gate electrode of the transistor 46 in the body portion 11. The gate line 47 is also connected to the transistor 46 in each body portion 11 arranged in the second direction X2. Note that although multiple gate lines 47 are arranged in the first direction X, only some of the multiple gate lines 47 are shown in Fig. 3.

[0041] The first detection line 48 is a wiring for detecting the potential at the first intermediate point P2 and extends from the first intermediate point P2. The first detection line 48 is disposed across the horizontal hinge portions 12B and the body portions 11, and extends in one direction in the second direction Y.

[0042] The second detection line 49 is a wiring for detecting the potential at the second intermediate point P4 and extends from the second intermediate point P4. The second detection line 49 is disposed across the horizontal hinge portions 12B and the body portions 11, and extends in the other direction in the second direction Y.

[0043] The strain detection circuit described above constitutes a Wheatstone bridge circuit, which will be described in detail below.

[0044] 7 is a schematic diagram of the Wheatstone bridge circuit of the first embodiment. The variable resistance value of the strain gauge 30 when the hinge portion 12 is not deformed is Rg. The first resistance value R1 of the first resistor portion 41, the second resistance value R2 of the second resistor portion 42, and the third resistance value R3 of the third resistor portion 43 are all equal to the variable resistance value Rg (Rg = R1 = R2 = R3). The first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are provided in the body portion 11. Therefore, the change in resistance value is zero even when the hinge portion 12 is deformed.

[0045] When detecting the amount of strain, a detection signal having a predetermined first potential V1 is supplied to the first potential line 44. A second potential V2 lower than the first potential V1 (V2>V1) is supplied to the second potential line 45. In this embodiment, the second potential V2 is 0 V. Therefore, when the transistor 46 is closed, the potential of the first connection point P1 becomes the first potential V1.

[0046] When the hinge portion 12 is not deformed, the resistance value of the strain gauge 30 remains at the variable resistance value Rg. Therefore, the variable resistance value Rg of the strain gauge 30 is equal to the first resistance value R1 of the first resistor portion 41, the second resistance value R2 of the second resistor portion 42, and the third resistance value R3 of the third resistor portion 43. Therefore, the potential V3 of the first intermediate point P2 read by the first detection line 48 is equal to the potential V4 of the second intermediate point P4 read by the second detection line 49.

[0047] On the other hand, the hinge portion 12 deforms, and the variable resistance value Rg of the strain gauge 30 changes. That is, the potential V3 at the first intermediate point P2 changes. A potential difference is then generated between the first intermediate point P2 and the second intermediate point P4. From the above, the amount of change in the resistance value of the strain gauge 30 can be detected by detecting the potentials V3 and V4.

[0048] Furthermore, the hinge portion 12 (vertical hinge portion 12A) provided with the strain gauge 30 and the body portion 11 provided with the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are adjacent to and connected to each other. Therefore, the temperatures of the hinge portion 12 and the body portion 11 are approximately the same. Therefore, the temperatures of the strain gauge 30, the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are also approximately the same.

[0049] Therefore, for example, if the temperature of the strain gauge 30 is high and the variable resistance value Rg is large, the temperatures of the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are also high, and therefore the values ​​of the first resistance value R1, the second resistance value R2, and the third resistance value R3 are also large. In other words, the variable resistance value Rg is prevented from becoming relatively large (or small) compared to the first resistance value R1, the second resistance value R2, and the third resistance value R3. Therefore, changes in resistance value (noise) due to temperature differences in the strain gauge 30 are not detected. Therefore, the amount of strain in the hinge portion 12 can be detected with high accuracy.

[0050] Furthermore, if the strain gauge 30, the first resistor 41, the second resistor 42, and the third resistor 43 are made of the same material, the magnitude of the resistance value that changes with temperature will also be the same. This is preferable because it reduces noise contained in the detection signal. However, the strain gauge 30, the first resistor 41, the second resistor 42, and the third resistor 43 of the present disclosure may be made of different materials.

[0051] 1 , in order to drive the strain detection circuit, the array layer 21 has a connection portion 101, a gate line driving circuit 102, a first potential line selection circuit 103, a second potential line selection circuit 104, a first detection line selection circuit 105, and a second detection line selection circuit 106. The connection portion 101, the gate line driving circuit 102, the first potential line selection circuit 103, the second potential line selection circuit 104, the first detection line selection circuit 105, and the second detection line selection circuit 106 are each arranged in a non-detection region 6 in a plan view, at an end of the stretchable device 100.

[0052] The connection portion 101 is for connecting to a driving IC (Integrated Circuit) arranged outside the stretchable device 100. The driving IC may be mounted as a COF (Chip On Film) on a flexible printed circuit board or a rigid board (not shown) connected to the connection portion 101.

[0053] The gate line driving circuit 102 is a circuit that drives a plurality of gate lines 47 (see FIG. 6 ) based on various control signals from the driving IC. The gate line driving circuit 102 selects the plurality of gate lines 47 sequentially or simultaneously, and supplies a gate driving signal to the selected gate lines 47.

[0054] The first potential line selection circuit 103 is a switch circuit that sequentially or simultaneously selects the multiple first potential lines 44. The first potential line selection circuit 103 connects the first potential lines 44 to the driving IC based on a selection signal supplied from the driving IC. As a result, a predetermined first potential V1 is applied to the first potential line 44.

[0055] The second potential line selection circuit 104 is a switch circuit that sequentially or simultaneously selects the plurality of second potential lines 45. The second potential line selection circuit 104 connects the second potential lines 45 to the driving IC based on a selection signal supplied from the driving IC. As a result, a predetermined second potential V2 is applied to the second potential lines 45.

[0056] The first detection line selection circuit 105 is a switch circuit that sequentially or simultaneously selects the multiple first detection lines 48. The first detection line selection circuit 105 connects the selected first detection line 48 to the driver IC based on a selection signal supplied from the driver IC. This causes the potential V3 of the first intermediate point P2 to be sent to the driver IC.

[0057] The second detection line selection circuit 106 is a switch circuit that sequentially or simultaneously selects the multiple second detection lines 49. The second detection line selection circuit 106 connects the selected second detection line 49 to the driver IC based on a selection signal supplied from the driver IC. This causes the potential V4 of the second intermediate point P4 to be sent to the driver IC.

[0058] 8 is a plan view of the body portion of the stretchable substrate as viewed from the first thickness direction. Next, details of the body portion 11 of the stretchable substrate 10 will be described. In the following description, the four sides of the body portion 11 will be referred to as a first side 201, a second side 202, a third side 203, and a fourth side 204 in the counterclockwise direction in a plan view (see FIG. 8). These four sides may be used to describe the orientation of each component.

[0059] 8 , the array layer 21 constituting the body portion 11 is provided with a first resistor portion 41, a second resistor portion 42, and a third resistor portion 43. The first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 have the same shape in a plan view. In the following description of the resistor portions, the first resistor portion 41 will be described as a representative example, and descriptions of the second resistor portion 42 and the third resistor portion 43 will be omitted.

[0060] The first resistor portion 41 has a plurality of straight wirings 210 and a plurality of intersecting wirings 220. The straight wirings 210 are electrical wirings that extend linearly along the planar direction. In this embodiment, the straight wirings 210 are parallel to the first side 201 and the third side 203. The intersecting wirings 220 are electrical wirings that extend from the ends of the straight wirings 210 in an intersecting direction that intersects with the straight wirings 210. Therefore, the intersecting wirings 220 are parallel to the second side 202 and the fourth side 204. The intersecting direction in this embodiment is a direction parallel to the second side 202 and the fourth side 204.

[0061] The multiple straight wirings 210 are arranged in the intersecting direction with a gap therebetween. Each intersecting wiring 220 is arranged between adjacent straight wirings 210. Each intersecting wiring 220 connects one end (end closer to the second side 202) of the straight wirings 210 to each other or the other end (end closer to the fourth side 204) of the straight wirings 210 to each other. The ends of the straight wirings 210 connected to the intersecting wirings 220 alternate in the intersecting direction between the one end and the other end. As a result, the multiple straight wirings 210 and the multiple intersecting wirings 220 form a single continuous wiring (first resistor section 41). Both ends of the first resistor section 41, the second resistor section 42, and the third resistor section 43 are connected to wiring (not shown) to form a Wheatstone bridge circuit.

[0062] 9 is a cross-sectional view taken along the line IX-IX. As shown in FIG. 9, the body portion 11 has a first surface 27 facing the first thickness direction Z1 and a second surface 28 facing the second thickness direction Z2. The first surface is formed by the surface of the array layer 21 facing the first thickness direction Z1 and faces away from the resin substrate 20. The first surface 27 is in contact with the second elastic resin 70 (see FIG. 2). The second surface 28 is formed by the surface of the resin substrate 20 in the second thickness direction Z2 and faces away from the array layer 21. The second surface 28 is in contact with the first elastic resin 60 (see FIG. 2).

[0063] The body portion 11 has a first insulating layer 23, a second insulating layer 24, and a third insulating layer 25 as multiple insulating layers that constitute the array layer 21. The first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are stacked on the first insulating layer 23 and covered by the second insulating layer 24 and the third insulating layer 25. When the strain detection circuit is driven, heat is generated from each of the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 and transferred to the array layer 21 and the resin substrate 20. The heat is then transferred from the first surface 27 of the body portion 11 through the second elastic resin 70. Alternatively, the heat is transferred from the second surface 28 of the body portion 11 through the first elastic resin 60.

[0064] The body portion 11 is formed with a heat dissipation opening 50 for improving the heat dissipation performance of the body portion 11. The heat dissipation opening 50 in the first embodiment is a first heat dissipation opening 51. The first heat dissipation opening 51 is recessed from the first surface 27 in the second thickness direction Z2 and opens toward the first thickness direction Z1 (outward in the thickness direction). A second elastic resin 70 (see FIG. 2 ) fills the first heat dissipation opening 51. The first heat dissipation opening 51 extends to the surface of the first insulating layer 23 in the first thickness direction Z1. Therefore, heat transferred to the array layer 21 is transferred not only from the first surface 27 but also from the second elastic resin 70 through the inner surface 51 a of the first heat dissipation opening 51. This improves the heat dissipation performance of the body portion 11.

[0065] 8 , the first heat dissipation openings 51 extend in the planar direction and are parallel to the first side 201 and the third side 203. This increases the contact area between the inner surface 51 a of the first heat dissipation opening 51 and the second elastic resin 70. The first heat dissipation openings 51 are also disposed between the linear wirings 210. This reduces the distance from the first resistor portion 41 to the first heat dissipation openings 51, making it easier for heat from the first resistor portion 41 to be dissipated through the first heat dissipation openings 51. Note that a plurality of the same first heat dissipation openings 51 are also provided near the second resistor portion 42 and the third resistor portion 43.

[0066] As described above, according to the first embodiment, a large amount of heat is generated from each of the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43, but this heat is easily dissipated through the heat dissipation opening 50. This prevents the temperatures of the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 from becoming relatively higher than that of the strain gauge 30. In other words, changes in resistance value (noise) caused by the temperature difference between the strain gauge 30 and the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are not detected. This allows the amount of strain in the hinge portion 12 to be detected with high accuracy. Furthermore, the heat dissipation opening 50 is provided only in a portion of the body portion 11, and the mechanical strength of the body portion 11 is maintained.

[0067] Although the first embodiment has been described above, the heat dissipation opening 50 of the present disclosure is not limited to the first heat dissipation opening 51. Next, other heat dissipation openings will be described.

[0068] (Variation 1) FIG. 10 is a cross-sectional view of the body portion of Variation 1. As shown in FIG. 10 , the heat dissipation opening 50 of the body portion 11A is a second heat dissipation opening 52. The second heat dissipation opening 52 is provided in the resin base material 20. The second heat dissipation opening 52 is recessed from the second surface 28 in the first thickness direction Z1 and opens toward the second thickness direction Z2 (outward in the thickness direction). A first elastic resin 60 (see FIG. 2 ) is inserted into the second heat dissipation opening 52. The second heat dissipation opening 52 is also offset in the planar direction relative to the linear wiring 210 so as not to overlap in the thickness direction. In other words, in a planar view, the second heat dissipation opening 52 is disposed between two adjacent linear wirings 210. As described above, according to Variation 1, heat from the body portion 11A is dissipated from the first surface 27, the second surface 28, and the inner surface 52 a of the second heat dissipation opening 52. Therefore, similarly to the first embodiment, the heat dissipation of the body portion 11A is high, and the amount of strain of the hinge portion 12 can be detected with high accuracy.

[0069] (Modification 2) Fig. 11 is a cross-sectional view of a body portion of Modification 2. As shown in Fig. 11, the heat dissipation opening 50 of the body portion 11B includes both the first heat dissipation opening 51 described in the first embodiment and the second heat dissipation opening 52 described in Modification 1. That is, the heat dissipation opening 50 is provided on both the first surface 27 and the second surface 28 of the body portion 11B. Note that the first heat dissipation opening 51 and the second heat dissipation opening 52 are not continuous in the thickness direction. According to Modification 2, heat from the body portion 11B is dissipated from the first surface 27, the second surface 28, the inner surface 51a of the first heat dissipation opening 51, and the inner surface 52a of the second heat dissipation opening 52, resulting in higher heat dissipation than in Embodiment 1 and Modification 1.

[0070] (Variation 3) Fig. 12 is a cross-sectional view of the body portion of Variation 3. As shown in Fig. 12, the heat dissipation opening 50 of the body portion 11C is the same as that of Variation 2 in that it includes both a first heat dissipation opening 51 and a second heat dissipation opening 52. However, the first heat dissipation opening 51 and the second heat dissipation opening 52 are continuous in the thickness direction. In other words, the heat dissipation opening 50 of Variation 3 is a through-hole 53 formed by the first heat dissipation opening 51 and the second heat dissipation opening 52. As described above, the body portion 11C of Variation 3 has a larger heat dissipation area than that of Variation 2, resulting in high heat dissipation performance.

[0071] (Modification 4) Fig. 13 is a cross-sectional view of the body portion of Modification 4. As shown in Fig. 13, the heat dissipation opening 50 of the body portion 11D is a second heat dissipation opening 54, which is the same as the second heat dissipation opening 52 of Modification 1 in that it is provided in the resin base material 20. However, the second heat dissipation opening 54 differs from the second heat dissipation opening 52 of Modification 1 in that it is arranged to overlap the straight wiring 210 in the thickness direction. With Modification 4, the body portion 11D has high heat dissipation properties, so the amount of strain in the hinge portion 12 can be detected with high accuracy.

[0072] (Modification 5) Fig. 14 is a cross-sectional view of a body portion of Modification 5. As shown in Fig. 14, the body portion 11E includes both the first heat dissipation opening 51 described in the first embodiment and the second heat dissipation opening 54 described in Modification 4. Furthermore, the first heat dissipation opening 51 and the second heat dissipation opening 54 are not continuous in the thickness direction. Even the body portion 11E of Modification 5 has high heat dissipation properties.

[0073] (Variation 6) Fig. 15 is a plan view of the body portion of Variation 6 as viewed from the second thickness direction. Note that in Fig. 15, the second resistor portion 42 and the third resistor portion 43 are not shown to make the heat dissipation opening 50 easier to see. As shown in Fig. 15, the heat dissipation opening 50 of Variation 6 is a second heat dissipation opening 55 formed on the second surface 28. The second heat dissipation opening 55 extends in the first direction X. In other words, the second heat dissipation opening 55 is not parallel to the linear wiring 210 of the first resistor portion 41 but intersects with it. Even in this variation, the heat dissipation area of ​​the body portion 11F is increased, resulting in high heat dissipation performance.

[0074] Although the embodiments and various modified examples have been described above, the present disclosure is not limited to the examples described in the embodiments, etc. For example, the heat dissipation openings are formed as grooves extending in the planar direction, but they may also be holes. Furthermore, if the heat dissipation openings are holes, multiple holes may be provided spaced apart in the planar direction. Note that, although the heat dissipation openings in the embodiments, etc., are filled with elastic resin, they may not be filled with elastic resin and may instead be empty spaces.

[0075] Although the strain detection circuit of this embodiment includes a switch element and a gate line for opening and closing the switch element, the present disclosure does not necessarily include a switch element and a gate line. In other words, the first potential line 44 and the second potential line 45 may be drawn out for each body portion 11 (each Wheatstone bridge circuit).

[0076] Furthermore, although the array layer 21 is configured with three insulating layers, the present disclosure is not limited to three. Furthermore, the shapes of the first resistor portion 41, the second resistor portion 42, and the third resistor portion 43 are not limited to the examples shown in the embodiments. Furthermore, although the widths of the wirings appear to be the same in each drawing, the present disclosure does not particularly limit the widths of the wirings, and the widths of the wirings may be different.

[0077] 5 Detection area 6 Non-detection area 10 Stretchable substrate 11, 11A, 11B, 11C, 11D, 11E, 11F Body part 12 Hinge part 19 Lightening hole 20 Resin base material 21 Array layer 23 First insulating layer 24 Second insulating layer 25 Third insulating layer 27 First surface 28 Second surface 30 Strain gauge 41 First resistance part 42 Second resistance part 43 Third resistance part 44 First potential line 45 Second potential line 46 Transistor 47 Gate line 48 First detection line 49 Second detection line 50 Heat dissipation opening 51 First heat dissipation opening 52, 54, 55 Second heat dissipation opening 53 Through hole 60 First stretchable resin 70 Second stretchable resin 100 Stretchable device 210 Straight wiring 220 Cross Wiring

Claims

1. A plate-shaped stretchable substrate having a plurality of lightening holes formed therethrough in a thickness direction, the stretchable substrate having a resin base material and an array layer laminated in this order in the thickness direction, when viewed from the thickness direction, the stretchable substrate is divided into a plurality of body portions and a plurality of hinge portions connecting the body portions together, the array layer including a strain detection circuit that detects the amount of strain in the hinge portions, the strain detection circuit comprising: a strain gauge that extends from the body portion to the hinge portion and turns back to the body portion; a first resistor that is disposed in the body portion where both ends of the strain gauge are disposed, one end connected to the other end of the strain gauge; a second resistor that is disposed in the body portion where both ends of the strain gauge are disposed, one end connected to one end of the strain gauge; and a third resistor that is disposed in the body portion where both ends of the strain gauge are disposed, one end connected to the other end of the second resistor and the other end connected to the other end of the first resistor. the body portion has: a first surface formed of the array layer and facing in a direction opposite to the resin substrate; and a second surface formed of the resin substrate and facing in a direction opposite to the array layer, wherein at least one of the first surface and the second surface has a heat dissipation opening that opens toward the outside in the thickness direction.

2. The stretchable device according to claim 1, wherein the heat dissipation openings that open outward in the thickness direction are formed on both the first surface and the second surface.

3. The stretchable device according to claim 2, wherein the first heat dissipation opening formed on the first surface and the second heat dissipation opening formed on the second surface are continuous in the thickness direction.

4. A stretchable device as described in claim 2, wherein the first heat dissipation opening formed on the first surface and the second heat dissipation opening formed on the second surface are not continuous in the thickness direction.

5. The stretchable device of claim 1, wherein the array layer is provided with three wirings constituting the first resistance portion, the second resistance portion, and the third resistance portion, the wirings comprising: a plurality of straight wirings arranged in the body portion and extending linearly along a plane direction in which the stretchable substrate extends; and a plurality of crossing wirings arranged in the body portion and extending from ends of the straight wirings in a crossing direction crossing the straight wirings, the plurality of straight wirings are arranged with spaces between them in the crossing direction, the plurality of crossing wirings are arranged one by one between adjacent straight wirings in the crossing direction, and connect one ends or the other ends of adjacent straight wirings in the crossing direction, the ends of the straight wirings connected by the plurality of crossing wirings alternate in the crossing direction, and the heat dissipation opening is a first heat dissipation opening formed in the first surface, and the first heat dissipation opening is arranged between adjacent straight wirings in the crossing direction.

6. The stretchable device according to claim 1, wherein the array layer is provided with three wirings constituting the first resistance portion, the second resistance portion, and the third resistance portion, the wirings comprising: a plurality of straight wirings arranged in the body portion and extending linearly along a plane direction in which the stretchable substrate extends; and a plurality of crossing wirings arranged in the body portion and extending from ends of the straight wirings in a crossing direction crossing the straight wirings, the plurality of straight wirings are arranged with spaces between them in the crossing direction, the plurality of crossing wirings are arranged one by one between the straight wirings adjacent to each other in the crossing direction, and connect one ends or the other ends of the straight wirings adjacent to each other in the crossing direction, the ends of the straight wirings connected by the plurality of crossing wirings alternate in the crossing direction, and the heat dissipation opening is a second heat dissipation opening formed in the second surface, and the second heat dissipation opening overlaps the straight wirings in the thickness direction.

7. A stretchable device according to any one of claims 1 to 6, comprising a pair of elastic resins sandwiching the stretchable substrate from both sides in the thickness direction.

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