Stretchable device

Abstract

A strain detection circuit of a stretchable substrate of this stretchable device includes: a strain gauge; a first resistance part having one end connected to the other end of the strain gauge; a second resistance part having one end connected to one end of the strain gauge; a third resistance part having one end connected to the other end of the second resistance part and the other end connected to the other end of the first resistance part; a first potential line for applying a first potential to a first connection point at which one end of the strain gauge and one end of the second resistance part are connected; a second potential line for applying a second potential lower than the first potential to a second connection point at which the other end of the first resistance part and the other end of the third resistance part are connected; a first detection line for detecting a potential at a first intermediate point at which the other end of the strain gauge and the first resistance part are connected; and a second detection line for detecting a potential at a second intermediate point at which the second resistance part and the third resistance part are connected.

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 a 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 to each other. 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 that extends from the body portion to the hinge portion and then 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 and has 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 and has one end connected to one end of the strain gauge, and a second resistor that is disposed in the body portion where both ends of the strain gauge are disposed and has one end connected to the other end of the second resistor and the other end connected to the first resistor. a third resistor portion connected to the other end of the strain gauge; a first potential line that applies a first potential to a first connection point where one end of the strain gauge and one end of the second resistor portion are connected; a second potential line that applies a second potential lower than the first potential to a second connection point where the other end of the first resistor portion and the other end of the third resistor portion are connected; a first detection line that detects the potential of a first intermediate point where the other end of the strain gauge and the first resistor portion are connected; and a second detection line that detects the potential of a second intermediate point where the other end of the second resistor portion and the third resistor portion are connected.

[0007] FIG. 1 is a plan view of a stretchable device according to a first embodiment. FIG. 2 is a schematic diagram of a cross section of the stretchable device according to the first embodiment, specifically a partial cross section of the detection region 5 of FIG. 1 , 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. 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 illustrating the layout of the strain detection circuit in a stretchable device according to a second embodiment, as viewed from a first thickness direction. FIG. 9 is a cross section taken along line VIII-VIII in FIG. 8 . FIG. 10 is a plan view illustrating the layout of the strain detection circuit in a stretchable device according to a third embodiment, as viewed from a first thickness direction. FIG. 11 is a plan view showing the layout of the strain detection circuit in the stretchable device of the fourth embodiment when viewed from the first 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] 2 is a diagram schematically illustrating a cross section of the stretchable device according to the first embodiment, and more specifically, a partial cross section of the detection region 5 in FIG. 1, 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. Thus, 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 (opposite 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 (opposite 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] Fig. 3 is an enlarged view of a portion of the stretchable substrate of embodiment 1. As shown in Fig. 3, when viewed in plan, the stretchable substrate 10 is divided into a plurality of body portions 11 and a plurality of hinge portions 12 that extend in a serpentine manner in the planar direction.

[0022] The body portion 11 has an octagonal shape in a plan view. The 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] 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] Fig. 4 is an enlarged view of the vertical hinge portion of the first embodiment. 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. Each bent portion 13 of this embodiment 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. 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] 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.

[0030] The array layer 21 is provided on a surface of the resin base material 20 in the first thickness direction Z1. The array layer 21 has a plurality of insulating layers (not shown) stacked in the thickness direction, and an electric circuit (strain detection circuit) whose insulation from the outside is ensured by the plurality of insulating layers. Next, the strain detection circuit included in the array layer 21 will be described in detail.

[0031] 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.

[0032] 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. Thus, the strain gauge 30 has 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). Furthermore, as shown in Fig. 6, a start end 31a and a finish end 32a of the strain gauge 30 are disposed in the body portion 11.

[0033] In this embodiment, strain gauges 30 are not provided in all hinge portions 12. Strain gauges 30 are provided only in vertical hinge portions 12A that overlap with the detection area 5. Therefore, strain gauges 30 are not provided in horizontal hinge portions 12B that overlap with the detection area 5 and in hinge portions 12 that overlap with the non-detection area 6. In the present disclosure, strain gauges 30 may be provided only in horizontal hinge portions 12B that overlap with the detection area 5, rather than in vertical hinge portions 12A that overlap with the detection area 5, or may be provided in all hinge portions 12 that overlap with the detection area 5; there are no particular limitations.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The strain detection circuit described above constitutes a Wheatstone bridge circuit, which will be described in detail below.

[0043] 7 is a schematic diagram of the Wheatstone bridge circuit of the first embodiment. The variable resistance of the strain gauge 30 when the hinge portion 12 is not deformed is represented by Rg. The first resistance R1 of the first resistor portion 41, the second resistance R2 of the second resistor portion 42, and the third resistance R3 of the third resistor portion 53 are all equal to the variable resistance Rg (Rg = R1 = R2 = R3). The second resistor portion 42, the third resistor portion 43, and the fourth resistor portion 54 are provided in the body portion 11. Therefore, the change in resistance is zero even when the hinge portion 12 is deformed.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] Although the first embodiment has been described above, the present disclosure is not limited to the example described in the first embodiment. For example, the strain detection circuit of the present embodiment includes a switch element and a gate line that opens and closes the switch element, but 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).

[0058] Next, another embodiment will be described showing a specific layout example of the strain detection circuit. Note that, although the other embodiment will be described using an example in which the strain detection circuit does not have switch elements and gate lines, the present disclosure also applies to a case in which the strain detection circuit has switch elements and gate lines.

[0059] (Embodiment 2) FIG. 8 is a plan view showing the layout of the strain detection circuit in a stretchable device of embodiment 2 when viewed from the first thickness direction. FIG. 9 is a cross-sectional view taken along line VIII-VIII in FIG. 8. In FIG. 8, hatching is applied to each layer to make it easier to distinguish the wiring of the strain detection circuit. The hatching in FIG. 8 is common to each insulating layer on which the wiring is stacked. In other words, for example, the wiring stacked on the first insulating layer is common to each other. Furthermore, the circles in FIG. 8 indicate connections with wiring on other layers. The same applies to the hatching and circles in FIGS. 10 and 11.

[0060] In the description of the second embodiment and subsequent embodiments, the four sides of the body 11 are 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 ( FIG. 8 ). The orientation of each component may be described using the four sides.

[0061] In the stretchable device 100A of the second embodiment, a first resistor portion 41A, a second resistor portion 42A, and a third resistor portion 43A are formed in the array layer 21 that constitutes the body portion 11. The first resistor portion 41A, the third resistor portion 43A, and the second resistor portion 42A are arranged in this order from the third side 203 of the body portion 11 toward the first side 201. The first resistor portion 41A, the second resistor portion 42A, and the third resistor portion 43A have the same shape in a planar view. Therefore, in describing the shapes of the resistor portions, the first resistor portion 41A will be described as a representative example, and descriptions of the second resistor portion 42A and the third resistor portion 43A will be omitted.

[0062] The first resistor portion 41A 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.

[0063] The multiple straight wirings 210 are arranged in the intersecting direction with gaps between them. Each intersecting wiring 220 is arranged between adjacent straight wirings 210. The intersecting wirings 220 connect one end (ends closer to the second side 202) of the straight wirings 210 to each other or the other end (ends closer to the fourth side 204) of the straight wirings 210 to each other. The ends of the straight wirings 210 to which the intersecting wirings 220 connect 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 portion 41A).

[0064] As shown in FIG. 9 , the array layer 21 constituting the body portion 11 includes a first insulating layer 22, a second insulating layer 23, a third insulating layer 24, and a fourth insulating layer 25, which are stacked in this order in the first thickness direction Z1. The first resistor portion 41A (a plurality of linear wirings 210 and a plurality of cross wirings 220) is stacked on the first insulating layer 22. Although not specifically shown, the second resistor portion 42A and the third resistor portion 43A are also stacked on the first insulating layer 22. The first strain gauge 31 of the strain gauge 30 is also stacked on the first insulating layer 22. That is, the first strain gauge 31, the first resistor portion 41A, the second resistor portion 42A, and the third resistor portion 43A are simultaneously deposited on the first insulating layer 22 and made of the same material. Therefore, the first strain gauge 31, the first resistor portion 41A, the second resistor portion 42A, and the third resistor portion 43A have the same temperature characteristics. That is, the resistance values ​​change in accordance with temperature changes, and the detection signal is less likely to contain noise.

[0065] 8, the strain detection circuit of this embodiment has a plurality of connection wires connecting the respective resistance parts. The plurality of connection wires are a first connection wire 231 connecting the first connection point P1 (the starting end 31a of the strain gauge 30) and one end of the second resistance part 42, a second connection wire 232 connecting the other end of the second resistance part 42A and one end of the third resistance part 43A, and a third connection wire 233 connecting the other end of the second resistance part 42A and the other end of the third resistance part 43A.

[0066] The first connection wiring 231, the second connection wiring 232, and the third connection wiring 233 each extend in a direction parallel to the first side 201. As shown in Fig. 9 , the first connection wiring 231, the second connection wiring 232, and the third connection wiring 233 are provided on the second insulating layer 23. In addition, although not shown in Fig. 9 , the first detection line 48A, the second detection line 49A, and the second strain gauge 32 are provided on the second insulating layer 23.

[0067] As shown in FIG. 8 , the directions in which the first potential line 44A, the second potential line 45A, the first detection line 48A, and the second detection line 49A extend are different from those in the first embodiment. Specifically, the first potential line 44A is drawn from the body portion 11 in one direction of the second direction Y. The second potential line 45A is drawn from the body portion 11 in the other direction of the second direction Y. The first detection line 48A is drawn from the body portion 11 in one direction of the first direction X. The second detection line 49A is drawn from the body portion 11 in the other direction of the first direction X. As shown in FIG. 8 , the first potential line 44A and the second potential line 45A are provided on the third insulating layer 24. The first potential line 44A is connected to one end of the first connection wiring 231. The second potential line 45A is connected to the other end of the third connection wiring 233.

[0068] As described above, in the stretchable device 100A of the second embodiment described above, the amount of strain in the hinge portion 12 can be detected with high accuracy, similar to the first embodiment.

[0069] 10 is a plan view showing the layout of the strain detection circuit in a stretchable device according to the third embodiment, as viewed from the first thickness direction. The strain detection circuit of the stretchable device 100B according to the third embodiment differs from that of the second embodiment in that it has serpentine wiring 330 instead of the straight wiring 210. The serpentine wiring 330 has a plurality of bent portions 331, similar to the hinge portion 12, and extends in a serpentine manner in a direction parallel to the first side 201 and the third side 203. According to the second embodiment, the shapes of the serpentine wiring 330 and the strain gauges 30 are similar. Therefore, the temperature difference between each resistor portion and the strain gauges 30 is small, and the amount of strain in the hinge portion 12 can be detected more accurately.

[0070] 11 is a plan view showing the layout of the strain detection circuit when viewed from the first thickness direction in a stretchable device according to embodiment 4. In FIG. 11, different hatching is applied to each layer to make it easier to distinguish the wiring of the strain detection circuit.

[0071] As shown in Fig. 11, the strain detection circuit of the stretchable device 100C of the fourth embodiment has a spiral wiring 400. The spiral wiring 400 is formed in a spiral shape around the center of the body portion 11. The spiral wiring 400 of this embodiment increases in diameter as it moves clockwise in a plan view. The spiral wiring 400 is divided into three parts in the length direction to form three resistance portions. The three resistance portions are arranged in order from the innermost side as a first resistance portion 41C, a third resistance portion 43C, and a second resistance portion 42C.

[0072] Although not specifically shown, the spiral wiring 400 and the first strain gauge 31 are formed on the first insulating layer 22. Furthermore, the spiral wiring 400 is disposed away from the center of the body portion 11 and closer to the four sides of the body portion 11. Therefore, there is space inside the spiral wiring 400 on the first insulating layer 22 (see FIG. 9 ) where other wiring, etc. can be formed.

[0073] Next, the wiring provided on the second insulating layer 23 (see FIG. 9 ) will be described. The first connection wiring 431, the second connection wiring 432, the third connection wiring 433, the second strain gauge 32, the second potential line 45C, and the first detection line 48C are provided on the second insulating layer 23. The first connection wiring 431 connects the starting end 31a of the strain gauge to one end of the second resistor 42C. The second connection wiring 432 connects the other end of the second resistor 42C to one end of the third resistor 43C. The third connection wiring 433 connects the other end of the second resistor 42C to the other end of the third resistor 43C. The ending end 32a of the strain gauge 30 is connected to one end of the first resistor 41C. The second potential line 45C is drawn from the third connection wiring 333 and extends over the horizontal hinge portion 12B. The first detection line 48C is connected to a first intermediate point P2 where the end 32a of the strain gauge and one end of the first resistor portion 41 are connected.

[0074] Next, the wiring provided on the third insulating layer 24 (see FIG. 9 ) will be described. A first potential line 44C and a second detection line 49C are provided on the third insulating layer 24. The first potential line 44C extends from the horizontal hinge portion 12B to the body portion 11, extends along the first side 201, and connects to the first connection point P1. The second detection line 49C extends from the vertical hinge portion 12A to the body portion 11, extends along the third side 203, and connects to the second intermediate point P4. As described above, the stretchable device 100C of the fourth embodiment described above can accurately detect the amount of strain in the hinge portion 12, just like the first embodiment.

[0075] Each embodiment has been described above, and although the width of each wire appears to be the same in each drawing, the present disclosure does not particularly limit the width of each wire, and the width of each wire may be different.

[0076] 5 Detection area 6 Non-detection area 10 Stretchable substrate 11 Body portion 12 Hinge portion 12A Vertical hinge portion 12B Horizontal hinge portion 13 Bending portion 20 Resin substrate 21 Array layer 22 First insulating layer 23 Second insulating layer 24 Third insulating layer 25 Fourth insulating layer 30 Strain gauge 41, 41A, 41C First resistance portion 42, 42A, 42C Second resistance portion 43, 43A, 43C Third resistance portion 44, 44A, 44C First potential line 45, 45A, 45C Second potential line 46 Transistor 47 Gate line 48, 48A, 48C First detection line 49, 49A, 49C Second detection line 60 First stretchable resin 70 Second stretchable resin 100, 100A, 100B, 100C Stretchable device 201 First edge 202 Second edge 203 Third edge 204 Fourth edge 210 Straight wiring 220 Intersecting wiring 231, 431 First connecting wiring 232, 432 Second connecting wiring 233, 433 Third connecting wiring 330 Serpentine wiring 331 Bent portion 400 Spiral wiring P1 First connecting point P2 First intermediate point P3 Second connecting point P4 Second intermediate point

Claims

1. A stretchable substrate having a plate shape and provided with a plurality of lightening holes that penetrate in the thickness direction, the stretchable substrate having a resin base material and an array layer that are 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 that connect the body portions together, the array layer includes 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, and has 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, and has 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, and has one end connected to the other end of the second resistor and the other end connected to the other end of the first resistor. a first potential line that applies a first potential to a first connection point where one end of the strain gauge and one end of the second resistor are connected; a second potential line that applies a second potential lower than the first potential to a second connection point where the other end of the first resistor and the other end of the third resistor are connected; a first detection line that detects the potential of a first intermediate point where the other end of the strain gauge and the first resistor are connected; and a second detection line that detects the potential of a second intermediate point where the other end of the second resistor and the third resistor are connected.

2. The stretchable device according to claim 1, wherein the array layer is provided with three wiring sections constituting the first resistance section, the second resistance section, and the third resistance section, the wiring sections comprising: a plurality of straight wirings arranged in the body section and extending linearly along a plane direction in which the stretchable substrate extends; and a plurality of crossing wirings arranged in the body section 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.

3. The stretchable device according to claim 1, wherein the array layer is provided with three wiring sections constituting the first resistance section, the second resistance section, and the third resistance section, the wiring sections comprising: a plurality of serpentine wirings arranged in the body section and extending in a serpentine manner along a plane direction in which the stretchable substrate extends; and a plurality of intersecting wirings arranged in the body section and extending from ends of the serpentine wirings in an intersecting direction intersecting the serpentine wirings, the plurality of serpentine wirings being arranged with spaces between them in the intersecting direction, the plurality of intersecting wirings being arranged one between each of the serpentine wirings adjacent to each other in the intersecting direction, and connecting one ends or the other ends of the serpentine wirings adjacent to each other in the intersecting direction, the ends of the serpentine wirings connected by the plurality of intersecting wirings being alternated in the intersecting direction.

4. The stretchable device according to claim 1, wherein one wiring section is provided in the array layer, the wiring section is arranged in the body section, and has spiral wiring that forms a spiral shape around the center of the body section when viewed in the thickness direction, and the spiral wiring is divided into three in the length direction to form the first resistance section, the second resistance section, and the third resistance section.

5. A stretchable device according to any one of claims 1 to 4, wherein the strain detection circuit has: a switch element interposed between the first potential line and the first connection point; and a gate line that opens and closes the switch element.

6. A stretchable device according to any one of claims 1 to 4, comprising a pair of elastic resin layers sandwiching the stretchable substrate from both sides in the thickness direction.

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