Deformation detection sensor and electronic device

Abstract

This deformation detection sensor comprises: a flexible film that exhibits changes in electrical characteristics due to deformation, said film having a first main surface and a second main surface facing in the opposite direction from the first main surface; and a plurality of first main surface electrodes that are provided to the first main surface at intervals from each other and that are electrically independent from each other. At least one of the plurality of first main surface electrodes is a detection electrode that outputs a change in electrical characteristics as an electric signal. Considering, in a plan view, virtual line segments passing between two adjacent first main surface electrodes from among the plurality of first main surface electrodes with two opposing points on the outer edge of the film defining the two ends thereof, there is no virtual line segment that does not pass through any of the plurality of first main surface electrodes.

Description

Deformation detection sensor and electronic device

[0001] The present invention relates to a deformation detection sensor and an electronic device.

[0002] A known example of a conventional invention related to a deformation detection sensor is the touch panel described in Patent Document 1. The touch panel described in Patent Document 1 is made of a molecularly oriented polylactic acid film. The polylactic acid film has a first main surface and a second main surface. Electrodes are formed on each of the first and second main surfaces. The electrode formed on the first main surface is a divided electrode electrically divided into at least four parts by a plurality of electrode dividing lines consisting of electrode-free portions. The electrode dividing lines are formed as straight lines having a predetermined width.

[0003] Patent No. 5819890

[0004] In the touch panel described in Patent Document 1, the deformation of the polylactic acid film may differ depending on whether the user presses on the divided electrodes or on the electrode dividing lines. Specifically, when the divided electrodes are pressed, the entire polylactic acid film is likely to bend. On the other hand, when the electrode dividing lines are pressed, only a portion of the polylactic acid film is likely to bend across the electrode dividing lines. When the entire polylactic acid film is bent, a relatively weak voltage is generated across the entire polylactic acid film. However, when only a portion of the polylactic acid film is bent, a relatively strong voltage is generated in only that portion of the polylactic acid film. Therefore, even if a user presses the touch panel with the same pressure, the voltage generated by the polylactic acid film may differ depending on the location of the pressure, making it difficult to estimate the magnitude of the pressure from the voltage generated by the polylactic acid film.

[0005] Therefore, an object of the present invention is to provide a deformation detection sensor and an electronic device that can suppress differences in the state of deformation of a film depending on differences in the pressed location.

[0006] A deformation detection sensor according to one embodiment of the present invention comprises: a flexible film whose electrical properties change with deformation, the film having a first main surface and a second main surface opposite the first main surface; and a plurality of first main surface electrodes provided on the first main surface, arranged at intervals along the planar direction of the first main surface, and electrically independent of each other, wherein at least one of the plurality of first main surface electrodes is a detection electrode that outputs a change in the electrical properties as an electrical signal, and when an imaginary line segment is considered that passes between two adjacent first main surface electrodes of the plurality of first main surface electrodes, with two opposing points on the outer edge of the film as both ends in a planar view, there is no imaginary line segment that does not pass through any of the plurality of first main surface electrodes.

[0007] According to the present invention, it is possible to prevent the film from deforming differently depending on the pressed location.

[0008] FIG. 1 is a perspective view of the deformation detection sensor 1. FIG. 2 is a plan view of the deformation detection sensor 1. FIG. 3 is a plan view of the detection electrode 3d. FIG. 4 is a plan view of the detection electrodes 3a, 3d, and 3e. FIG. 5 is a plan view of the deformation detection sensor 1 showing the imaginary line segment il1. FIG. 6 is a plan view of the deformation detection sensor 50. FIG. 7 is a cross-sectional view showing the deformation of the deformation detection sensor 50 when a point PP1 on the detection electrode 3e is pressed. FIG. 8 is a cross-sectional view showing the deformation of the deformation detection sensor 50 when a point PP2 on the imaginary line segment ILc is pressed. FIG. 9 is a cross-sectional view showing the deformation of the deformation detection sensor 1 when a point PP1 on the detection electrode 3e is pressed. FIG. 10 is a cross-sectional view showing the deformation of the deformation detection sensor 1 when a point PP3 on the electrode-free portion 5 is pressed. FIG. 11 is an exploded perspective view of the electronic device 20. FIG. 12 is a plan view of the deformation detection sensor 1a. FIG. 13 is a plan view of touch panel electrodes 86, 87 and detection electrodes 3a to 3f. FIG. 14 is a plan view of deformation detection sensor 1b. FIG. 15 is a plan view of detection electrode 3e. FIG. 16 is a plan view of detection electrode 3e and reinforcing electrode 10g. FIG. 17 is a model diagram of deformation detection sensor 1b. FIG. 18 is a plan view of deformation detection sensor 1c. FIG. 19 is a plan view of deformation detection sensor 1d. FIG. 20 is a plan view of deformation detection sensor 1e. FIG. 21 is a plan view of deformation detection sensor 1f. FIG. 22 is a plan view of deformation detection sensor 1g. FIG. 23 is a plan view of deformation detection sensor 1h. FIG. 24 is a plan view of deformation detection sensor 1i.

[0009] [First Embodiment] A deformation detection sensor 1 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of the deformation detection sensor 1. Fig. 2 is a plan view of the deformation detection sensor 1. Fig. 3 is a plan view of the detection electrode 3d. Fig. 4 is a plan view of the detection electrodes 3a, 3d, and 3e. Fig. 5 is a plan view of the deformation detection sensor 1 showing the imaginary line segment il1. Note that in Fig. 3, reference symbols are assigned only to representative first convex portions T1 and representative second concave portions O2 out of the plurality of first convex portions T1 and representative second concave portions O2.

[0010] In the deformation detection sensor 1, directions are defined as follows, for example. As shown in FIG. 1 , the direction in which the front and rear edges of the upper main surface US2 extend is defined as the left-right direction. The direction in which the left and right edges of the upper main surface US2 extend is defined as the front-rear direction. The direction in which the upper main surface US2 and the lower main surface DS2 are aligned is defined as the up-down direction. The left-right direction, front-rear direction, and up-down direction are perpendicular to each other. Viewing in an upward or downward direction corresponds to a planar view according to the present invention. Furthermore, a direction perpendicular to the up-down direction corresponds to the planar direction of the first main surface according to the present invention. The left-right direction and front-rear direction are examples of the planar direction of the first main surface according to the present invention. However, the left-right direction, front-rear direction, and up-down direction in this specification are defined for convenience of explanation and may not coincide with the left-right direction, front-rear direction, and up-down direction when the deformation detection sensor 1 is in use. Furthermore, in each drawing, the left direction and the right direction may be interchanged, the front direction and the rear direction may be interchanged, and the up direction and the down direction may be interchanged.

[0011] The deformation detection sensor 1 detects deformation of an object to be measured. The deformation detection sensor 1 is flexible. As shown in FIG. 1 , the deformation detection sensor 1 includes a piezoelectric film 2, detection electrodes 3a to 3i, and a reference electrode 4. Any of the detection electrodes 3a to 3i, the piezoelectric film 2, and the reference electrode 4 are arranged in this order downward. The piezoelectric film 2 and the reference electrode 4 correspond to the film and second principal surface electrode, respectively, according to the present invention. In this embodiment, the detection electrodes 3a to 3i correspond to the plurality of first principal surface electrodes according to the present invention.

[0012] The piezoelectric film 2 is flexible. The piezoelectric film 2 is flat. The piezoelectric film 2 has an upper principal surface US2 and a lower principal surface DS2 arranged in this order in a downward direction. The lower principal surface DS2 faces the upper principal surface US2. In this embodiment, the upper principal surface US2 and the lower principal surface DS2 are each rectangular having a front side and a rear side extending in the left-right direction and a left side and a right side extending in the front-to-back direction. The upper principal surface US2 and the lower principal surface DS2 correspond to the first principal surface and the second principal surface, respectively, according to the present invention. However, the shape and arrangement of the film according to the present invention are not limited to the shape and arrangement of the piezoelectric film 2.

[0013] The piezoelectric film 2 is polarized by deformation, generating a potential difference between the upper principal surface US2 and the lower principal surface DS2. The potential difference generated between the upper principal surface US2 and the lower principal surface DS2 depends on the amount of deformation of the piezoelectric film 2. Note that if the amount of deformation of the piezoelectric film 2 differs from part to part of the piezoelectric film 2, the potential difference generated between the upper principal surface US2 and the lower principal surface DS2 will differ from part to part of the upper principal surface US2.

[0014] The piezoelectric film 2 is, for example, a film formed from a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA), such as poly-L-lactic acid (PLLA) or poly-D-lactic acid (PDLA). The PLA has a helical structure in its main chain. PLA has piezoelectricity due to the orientation of its molecules after uniaxial stretching. The piezoelectric film 2 has a piezoelectric constant of d14.

[0015] The PLA is stretched in a uniaxial stretching direction. In this embodiment, the uniaxial stretching direction of the PLA forms an angle of 45 degrees with respect to each of the left-right direction and the front-back direction. Note that the 45 degrees may be within a range of approximately 45 degrees ±10 degrees. When the piezoelectric film 2 is stretched or compressed along the left-right direction, a potential difference is generated between the upper principal surface US2 and the lower principal surface DS2. Similarly, when the piezoelectric film 2 is stretched or compressed along the front-back direction, a potential difference is generated between the upper principal surface US2 and the lower principal surface DS2. In this embodiment, the magnitude of the potential difference generated between the upper principal surface US2 and the lower principal surface DS2 is proportional to the differential value of the deformation amount of the piezoelectric film 2. Note that the uniaxial stretching direction of the PLA may form an angle of 0 degrees or 90 degrees with respect to the left-right direction. The 0 degrees and 90 degrees may be within a range of approximately 0 degrees ±10 degrees and approximately 90 degrees ±10 degrees, respectively.

[0016] The reference electrode 4 is flexible and conductive. The material of the reference electrode 4 is, for example, copper. The reference electrode 4 is in the form of a flat film. The reference electrode 4 is provided on the lower main surface DS2. The reference electrode 4 covers the entire lower main surface DS2. The reference electrode 4 functions as a reference electrode and a shield conductor by being connected to the ground potential. The shape and arrangement of the reference electrode 4 are not limited to those shown in this embodiment. Furthermore, the reference electrode 4 is not an essential component of the present invention. Furthermore, the reference electrode 4 does not necessarily have to cover the entire lower main surface DS2, and may cover substantially the entire lower main surface DS2.

[0017] Each of the detection electrodes 3a to 3i is electrically conductive. The material of each of the detection electrodes 3a to 3i is, for example, copper. Each of the detection electrodes 3a to 3i is in the form of a flat film. Each of the detection electrodes 3a to 3i is provided on the upper main surface US2. More specifically, the detection electrodes 3a to 3i are provided on the upper main surface US2 at intervals from each other in the left-right direction and the front-back direction, and are electrically independent from each other. Note that each of the detection electrodes 3a to 3i does not have to be in the form of a flat film.

[0018] As shown in FIG. 2, the detection electrodes 3a to 3i are arranged in a matrix of 3 rows and 3 columns. The detection electrodes 3a to 3c are arranged at equal intervals along the right direction. Similarly, the detection electrodes 3d to 3f are arranged at equal intervals along the right direction. The detection electrodes 3g to 3i are arranged at equal intervals along the right direction. Furthermore, the detection electrodes 3a, 3d, and 3g are arranged at equal intervals along the rear direction. Similarly, the detection electrodes 3b, 3e, and 3h are arranged at equal intervals along the rear direction. The detection electrodes 3c, 3f, and 3i are arranged at equal intervals along the rear direction. Note that the detection electrodes 3a to 3i do not have to be arranged in a matrix.

[0019] Each of the detection electrodes 3a to 3i functions as an electrode for outputting the potential difference generated by the piezoelectric film 2 as an electric charge. That is, each of the detection electrodes 3a to 3i outputs the potential difference generated by the piezoelectric film 2 as an electric signal. More specifically, each of the detection electrodes 3a to 3i outputs an electric charge according to the amount of deformation of the portion of the piezoelectric film 2 located directly below the detection electrode 3a to 3i. Each of the detection electrodes 3a to 3i is harder than the piezoelectric film 2. The number of detection electrodes is not limited to nine. Each of the detection electrodes 3a to 3i does not have to be harder than the piezoelectric film 2.

[0020] When viewed from below, the detection electrodes 3a to 3i are congruent to one another. Furthermore, when viewed from below, the areas of the detection electrodes 3a to 3i are equal to one another. More specifically, when viewed from below, by translating the detection electrode 3a, it can be superimposed on each of the detection electrodes 3c, 3e, 3g, and 3i. When viewed from below, by rotating the detection electrode 3a 90 degrees clockwise and translating it, it can be superimposed on each of the detection electrodes 3b, 3d, 3f, and 3h. Note that when viewed from below, the detection electrodes 3a to 3i do not have to be congruent to one another. Furthermore, when viewed from below, the areas of the detection electrodes 3a to 3i may be different from one another.

[0021] Here, the shape and arrangement of detection electrodes 3d and 3e will be described in detail as an example of two adjacent detection electrodes among the detection electrodes 3a to 3i. Note that two adjacent detection electrodes refer to any two of the detection electrodes 3a to 3i, with no other detection electrodes located between them. In the case of detection electrodes 3d and 3e, none of the detection electrodes 3a to 3c or 3f to 3i are located between the two detection electrodes 3d and 3e. Detection electrode 3d is also adjacent to detection electrodes 3a and 3g. Note that detection electrodes 3d, 3e, and 3a correspond to the first, second, and third detection electrodes, respectively, according to the present invention. However, the first, second, and third detection electrodes according to the present invention are not limited to detection electrodes 3d, 3e, and 3a, respectively. Furthermore, detection electrode 3d does not have to be adjacent to detection electrodes 3a and 3g either.

[0022] As shown in FIG. 3 , when viewed from below, the detection electrode 3d includes a first convex portion T1. When viewed from below, the shape of the detection electrode 3d is such that the first convex portion T1 is provided on at least one of the four sides S1 to S4 of a rectangle VR1. When viewed from below, the shape of the detection electrode 3d is such that a second concave portion O2 is provided on at least one of the sides on which the first convex portion T1 is not provided. More specifically, the rectangle VR1 has sides S1 to S4. The sides S1 and S3 each extend in the front-to-rear direction. The side S1 is located to the right of the side S3. The sides S2 and S4 each extend in the left-to-right direction. The side S2 is located in front of the side S4. When viewed from below, the detection electrode 3d does not necessarily have to include the first convex portion T1.

[0023] The first convex portions T1 are provided on the sides S1 and S3. The second concave portions O2 are provided on the sides S2 and S4. The first convex portion T1 provided on the side S3 has a shape that is bilaterally symmetrical with the first convex portion T1 provided on the side S1, and therefore a description thereof will be omitted. The second concave portion O2 provided on the side S4 has a shape that is front-to-back symmetrical with the second concave portion O2 provided on the side S2, and therefore a description thereof will be omitted. The sides S1 and S2 correspond to the first and second sides, respectively, according to the present invention. However, the first and second sides according to the present invention are not limited to the sides S1 and S2, respectively. The shapes of the detection electrodes 3a to 3i are not limited to those shown in this embodiment.

[0024] As shown in FIG. 4 , the first protrusion T1 provided on the side S1 protrudes to the right from the side S1. The rightward direction is the direction from the detection electrode 3d toward the detection electrode 3e, which corresponds to the first direction according to the present invention. As shown in FIG. 3 , the length LPA1 of the portion PA1 where the side S1 and the first protrusion T1 contact each other is greater than or equal to ¼ and less than 1 / 2 the length LS1 of the side S1. In this embodiment, the length LPA1 of the portion PA1 where the side S1 and the first protrusion T1 contact each other is ¼ of the length LS1 of the side S1. The length LPA1 of the portion PA1 where the side S1 and the first protrusion T1 contact each other can also be considered the maximum length of the first protrusion T1 in the rear direction.

[0025] 4, the detection electrode 3e includes a first recess O1 recessed to the right. The first recess O1 and the first protrusion T1 face each other. When viewed from below, the first recess O1 and the first protrusion T1 face each other.

[0026] The second recess O2 provided on the side S2 is recessed rearward from the side S2. The rearward direction is the direction from the detection electrode 3a toward the detection electrode 3d and corresponds to the second direction according to the present invention. As shown in FIG. 3 , the length LPA2 of the portion PA2 where the side S2 and the second recess O2 contact is greater than or equal to ¼ and less than 1 / 2 the length LS2 of the side S2. In this embodiment, the length LPA2 of the portion PA2 where the side S2 and the second recess O2 contact is ¼ of the length LS2 of the side S2. The length LPA2 of the portion PA2 where the side S2 and the second recess O2 contact can also be considered the maximum length of the second recess O2 in the rightward direction.

[0027] 4, the detection electrode 3a includes a second protrusion T2 that protrudes rearward. The second protrusion T2 and the second recess O2 face each other. When viewed from below, the second protrusion T2 and the second recess O2 face each other.

[0028] 5, consider a virtual line segment that, when viewed from below, has two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends and passes between two adjacent detection electrodes 3a to 3i. Consider virtual line segment il1 as an example of a virtual line segment that has two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends and passes between two adjacent detection electrodes 3a to 3i.

[0029] The imaginary line segment il1 is an imaginary line segment having two opposing points A and B at its ends on the outer edge OE2 of the piezoelectric film 2. The imaginary line segment il1 passes between the detection electrodes 3a and 3b, between the detection electrodes 3d and 3e, and between the detection electrodes 3g and 3h. The imaginary line segment il1 also passes through the detection electrodes 3b, 3d, and 3h.

[0030] Similar to the case of the virtual line segment il1, when a virtual line segment is considered to pass between two adjacent detection electrodes 3a to 3i, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as both ends, in the deformation detection sensor 1, the virtual line segment passes through at least one of the detection electrodes 3a to 3i when viewed from below. In other words, when a virtual line segment is considered to pass between two adjacent detection electrodes 3a to 3i, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as both ends, in the case of the deformation detection sensor 1, the virtual line segment does not pass through any of the detection electrodes 3a to 3i.

[0031] The deformation detection sensor 1 can prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location. As a comparative example, a deformation detection sensor 50 will first be described with reference to the drawings. Fig. 6 is a plan view of the deformation detection sensor 50. Regarding the deformation detection sensor 50, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0032] 6, in the deformation detection sensor 50, the detection electrodes 3a to 3i are divided by electrode-free portions 5. In the deformation detection sensor 50, as in the deformation detection sensor 1, an imaginary line segment is considered that passes between two adjacent detection electrodes, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends, when viewed from below. Here, imaginary line segments ILa to ILd are considered as an example of an imaginary line segment that passes between two adjacent detection electrodes, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends.

[0033] The imaginary line segment ILa is a virtual line segment having two opposing points C and D on the outer edge OE2 of the piezoelectric film 2 as its both ends. The imaginary line segment ILa passes between the detection electrodes 3a and 3d, between the detection electrodes 3b and 3e, and between the detection electrodes 3c and 3f. The imaginary line segment ILa does not pass through any of the detection electrodes 3a to 3i. Therefore, when viewed from below, the imaginary line segment ILa is a virtual line segment IL having two opposing points on the outer edge OE2 of the piezoelectric film 2 as its both ends and passing between any two adjacent detection electrodes 3a to 3i, but does not pass through any of the detection electrodes 3a to 3i.

[0034] The imaginary line segment ILb is also an imaginary line segment IL, similar to the imaginary line segment ILa.

[0035] The imaginary line segment ILc is an imaginary line segment having two opposing points E and F on the outer edge OE2 of the piezoelectric film 2 as its ends. The imaginary line segment ILc passes between the detection electrodes 3a and 3b, between the detection electrodes 3d and 3e, and between the detection electrodes 3g and 3h. The imaginary line segment ILc does not pass through any of the detection electrodes 3a to 3i. Therefore, the imaginary line segment ILc is the imaginary line segment IL.

[0036] The imaginary line segment ILd is also an imaginary line segment IL, similar to the imaginary line segment ILc.

[0037] In the deformation detection sensor 50, there is a virtual line segment IL, such as the virtual line segments ILa to ILd, which, when viewed downward, have two opposing points on the outer edge OE2 of the piezoelectric film 2 as their ends and pass between two adjacent detection electrodes 3a to 3i, but do not pass through any of the detection electrodes 3a to 3i.

[0038] In the case of the deformation detection sensor 50, the deformation of the piezoelectric film 2 may differ depending on whether the user presses a point on any of the detection electrodes 3a to 3i or a point on the imaginary line segments ILa to ILd. Fig. 7 is a cross-sectional view showing the deformation of the deformation detection sensor 50 when point PP1 on the detection electrode 3e is pressed. Fig. 8 is a cross-sectional view showing the deformation of the deformation detection sensor 50 when point PP2 on the imaginary line segment ILc is pressed.

[0039] For example, when a user presses point PP1 on detection electrode 3e downward, the entire piezoelectric film 2 deforms and curves downward, as shown in Figure 7. Similarly, when a user presses points on detection electrodes 3a to 3d and 3f to 3i downward, the entire piezoelectric film 2 deforms and curves downward. When a user presses points on detection electrodes 3a to 3i downward, the entire piezoelectric film 2 deforms and curves downward, and a relatively weak voltage is generated across the entire piezoelectric film 2.

[0040] On the other hand, for example, when a user presses point PP2 on the imaginary line segment ILc downward, as shown in FIG. 8 , the piezoelectric film 2 deforms so that only a portion of the piezoelectric film 2 bends, with the imaginary line segment ILc as a boundary. Similarly, when a user presses points on the imaginary line segments ILa, ILb, and ILd downward, only a portion of the piezoelectric film 2 bends, with the imaginary line segments ILa, ILb, and ILd as a boundary, respectively. In other words, the imaginary line segments ILa, ILb, and ILd can serve as folding boundaries. When a user presses points on the imaginary line segments ILa to ILd downward, only a portion of the piezoelectric film 2 bends, and a relatively strong voltage is generated only in that portion of the piezoelectric film 2. In other words, the deformation of the piezoelectric film 2 differs when a user presses points on the detection electrodes 3a to 3i downward and when a user presses points on the imaginary line segments ILa to ILd downward. Therefore, even if the user presses the deformation detection sensor 50 with the same pressure, the voltage generated by the piezoelectric film 2 will differ depending on the location of the pressure, which may make it difficult to estimate the magnitude of the pressure from the voltage generated by the piezoelectric film 2.

[0041] Next, the deformation detection sensor 1 will be described with reference to the drawings. Fig. 9 is a cross-sectional view showing deformation of the deformation detection sensor 1 when a point PP1 on the detection electrode 3e is pressed. Fig. 10 is a cross-sectional view showing deformation of the deformation detection sensor 1 when a point PP3 on the electrode-free portion 5 is pressed.

[0042] For example, when a user presses point PP1 on detection electrode 3e downward, the entire piezoelectric film 2 deforms and curves downward, as shown in Figure 9. Similarly, when a user presses points on detection electrodes 3a to 3d and 3f to 3i downward, the entire piezoelectric film 2 deforms and curves downward. When a user presses points on detection electrodes 3a to 3i downward, the entire piezoelectric film 2 deforms and curves downward, and a relatively weak voltage is generated across the entire piezoelectric film 2.

[0043] Similarly, when a user presses point PP3 on the non-electrode portion 5 downward, the entire piezoelectric film 2 similarly deforms to curve downward, as shown in FIG. 10 . When a user presses point PP3 on the non-electrode portion 5 downward, the entire piezoelectric film 2 also deforms to curve, and a relatively weak voltage is generated throughout the entire piezoelectric film 2. In the deformation detection sensor 1, when a user presses point PP3 on the non-electrode portion 5 downward, the entire piezoelectric film 2 deforms to curve because, when viewed from below in the deformation detection sensor 1, two opposing points on the outer edge OE2 of the piezoelectric film 2 are considered as two imaginary line segments passing between two adjacent detection electrodes 3a-3i, no imaginary line segment IL does not pass through any of the detection electrodes 3a-3i. In other words, when viewed from below, two opposing points on the outer edge OE2 of the piezoelectric film 2 are considered as two imaginary line segments passing between two adjacent detection electrodes 3a-3i, and no imaginary line segment IL does not pass through any of the detection electrodes 3a-3i. That is, when a user presses downward a point on one of the detection electrodes 3a to 3i, the piezoelectric film 2 deforms in the same manner as when the user presses downward a point on the electrode-free portion 5. Therefore, the deformation detection sensor 1 can prevent the deformation of the piezoelectric film 2 from differing depending on the pressing location. As a result, when a user presses the deformation detection sensor 50 with the same pressing force, the voltage generated by the piezoelectric film 2 will be approximately the same even if the pressing location is different. Therefore, the deformation detection sensor 1 can accurately estimate the magnitude of the pressing force from the voltage generated by the piezoelectric film 2.

[0044] In this embodiment, since the first recess O1 and the first protrusion T1 face each other when viewed from below, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3 a to 3 i, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends, there is no imaginary line segment IL that does not pass through any of the detection electrodes 3 a to 3 i. The first protrusion T1 prevents deformation so that only a portion of the piezoelectric film 2 bends when a user presses a point PP3 on the electrode-free portion 5 downward.

[0045] The deformation detection sensor 1 can further suppress variations in the deformation of the piezoelectric film 2 depending on the location of pressure. More specifically, the length LPA1 of the portion PA1 where the side S1 and the first convex portion T1 contact each other is greater than or equal to ¼ and less than 1 / 2 the length LS1 of the side S1. That is, the proportion of the first convex portion T1 in the detection electrode 3d is relatively large. As described above, the first convex portion T1 suppresses deformation such that only a portion of the piezoelectric film 2 bends when a user presses a point PP3 on the non-electrode portion 5 downward. Therefore, when the shape of the detection electrode 3d is such that the first convex portion T1 is provided on at least one of the four sides S1 to S4 of the rectangle VR1 when viewed from below, the larger the proportion of the first convex portion T1 in the detection electrode 3d, the more effectively the deformation of the piezoelectric film 2 depending on the location of pressure can be suppressed.

[0046] The deformation detection sensor 1 can further prevent the piezoelectric film 2 from deforming differently depending on the location of pressure. More specifically, when viewed from below, the second recess O2 of the detection electrode 3d and the second protrusion T2 of the detection electrode 3a face each other. Furthermore, the length LPA2 of the portion PA2 where the side S2 and the second recess O2 meet is greater than or equal to ¼ and less than 1 / 2 the length LS2 of the side S2. This allows for a larger proportion of the detection electrode 3a occupied by the second protrusion T2. ​​Like the first protrusion T1, the second protrusion T2 also prevents deformation of only a portion of the piezoelectric film 2 from bending when a user presses downward at point PP3 on the non-electrode portion 5. Therefore, the deformation detection sensor 1 can further prevent the piezoelectric film 2 from deforming differently depending on the location of pressure.

[0047] The deformation detection sensor 1 can suppress variations in the parasitic capacitance formed between each of the detection electrodes 3a to 3i and the reference electrode 4. More specifically, each of the detection electrodes 3a to 3i faces the reference electrode 4 via the piezoelectric film 2. Therefore, a parasitic capacitance is formed between each of the detection electrodes 3a to 3i and the reference electrode 4. This parasitic capacitance may cause unpredictable resonance or the like in a circuit to which the detection electrodes 3a to 3i and the reference electrode 4 are connected. Therefore, in the deformation detection sensor 1, the areas of the detection electrodes 3a to 3i are equal to one another when viewed from below. This makes it easy to make the areas where each of the detection electrodes 3a to 3i faces the reference electrode 4 approximately uniform. Therefore, variations in the parasitic capacitance formed between each of the detection electrodes 3a to 3i and the reference electrode 4 can be suppressed and made approximately uniform. As a result, the occurrence of unpredictable resonance or the like can be suppressed in a circuit to which the detection electrodes 3a to 3i and the reference electrode 4 are connected.

[0048] In this embodiment, the detection electrodes 3a to 3i are congruent with one another when viewed from below. This makes it easier to make the areas where the detection electrodes 3a to 3i face the reference electrode 4 substantially uniform. This further reduces variations in the parasitic capacitance formed between the detection electrodes 3a to 3i and the reference electrode 4.

[0049] Furthermore, the deformation detection sensor 1 can instantly detect pressure. More specifically, piezoelectric elements have excellent responsiveness. When the piezoelectric film 2 deforms, a potential difference is instantly generated between the upper principal surface US2 and the lower principal surface DS2. As a result, the deformation detection sensor 1 can instantly detect pressure.

[0050] Furthermore, in the deformation detection sensor 1, the reference electrode 4 covers substantially the entire lower main surface DS2, thereby preventing noise from entering the piezoelectric film 2.

[0051] [First Modification] An electronic device 20 and a deformation detection sensor 1a according to a first modification of the present invention will be described below with reference to the drawings. FIG. 11 is an exploded perspective view of the electronic device 20. FIG. 12 is a plan view of the deformation detection sensor 1a. FIG. 13 is a plan view of the touch panel electrodes 86, 87 and the detection electrodes 3a to 3f. Note that in FIGS. 11 and 13, reference symbols are assigned only to representative touch panel electrodes 86, 87. Also, in FIG. 13, for ease of explanation, the outer edges OE3a to OE3f of the detection electrodes 3a to 3f are drawn with thick lines. Regarding the deformation detection sensor 1a, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0052] 11, an electronic device 20 includes a deformation detection sensor 1a and a touch panel 6. The deformation detection sensor 1a differs from the deformation detection sensor 1 in that the number of detection electrodes is six and in the shapes of the detection electrodes 3a to 3f. However, in this modification, the detection electrodes 3a to 3f are also congruent with one another when viewed from below. More specifically, when viewed from below, translating the detection electrode 3a allows it to overlap with each of the detection electrodes 3b to 3f.

[0053] The touch panel 6 is plate-shaped. The touch panel 6 has an upper main surface US6 and a lower main surface DS6 arranged in this order along a downward direction. The lower main surface DS6 faces the upper main surface US6. The upper main surface US6 and the lower main surface DS6 each have a rectangular shape with front and rear sides extending in the left-right direction and left and right sides extending in the front-to-back direction. The upper main surface US6 and the lower main surface DS6 correspond to the third main surface and the fourth main surface according to the present invention, respectively. However, the shapes of the third main surface and the fourth main surface according to the present invention are not limited to the shapes of the upper main surface US6 and the lower main surface DS6, respectively.

[0054] The touch panel 6 includes a surface panel 7, a touch sensor 8, and a display 9. The surface panel 7 is plate-shaped. The surface panel 7 is transparent. The surface panel 7 is made of, for example, glass. The surface panel 7 has an upper main surface and a lower main surface arranged in this order along a downward direction. The upper and lower main surfaces of the surface panel 7 are each rectangular, having front and rear sides extending in the left-right direction and left and right sides extending in the front-to-back direction. A user touches or presses the upper main surface of the surface panel 7 using a pen, the user's own finger, or the like. That is, the upper main surface of the surface panel 7 is pressed by the user. In this modification, the upper main surface of the surface panel 7 corresponds to the upper main surface US6 of the touch panel 6.

[0055] The touch sensor 8 is, for example, a capacitance-type sensor. The touch sensor 8 includes a first electrode sheet 81 and a second electrode sheet 82. The first electrode sheet 81 is flat. The first electrode sheet 81 has an upper main surface and a lower main surface that are arranged in this order along a downward direction. The upper main surface and the lower main surface of the first electrode sheet 81 are each rectangular having a front side and a rear side extending in the left-right direction and a left side and a right side extending in the front-rear direction. In this modified example, the upper main surface of the first electrode sheet 81 is attached to the lower main surface of the surface panel 7 by an adhesive member (not shown). A plurality of touch panel electrodes 86 are provided on the lower main surface of the first electrode sheet 81. The plurality of touch panel electrodes 86 are arranged in a matrix of 6 rows and 11 columns.

[0056] The second electrode sheet 82 is in the form of a flat film. The second electrode sheet 82 has an upper main surface and a lower main surface arranged in this order along a downward direction. The upper and lower main surfaces of the second electrode sheet 82 are each rectangular having a front side and a rear side extending in the left-right direction and a left side and a right side extending in the front-to-back direction. A plurality of touch panel electrodes 87 are provided on the upper main surface of the second electrode sheet 82. In this modified example, the upper main surface of the second electrode sheet 82 is attached to the lower main surface of the first electrode sheet 81 by an adhesive member (not shown). The plurality of touch panel electrodes 87 are arranged in a matrix of 6 rows and 10 columns.

[0057] When viewed from below, the multiple touch panel electrodes 86 do not overlap with the multiple touch panel electrodes 87. When viewed from below, adjacent touch panel electrodes 86, 87 are capacitively coupled, and the touch sensor 8 detects a touch operation or a pressing operation by the user on the surface panel 7 based on a change in capacitance between the adjacent touch panel electrodes 86, 87. The touch sensor 8 is made of a transparent material. The first electrode sheet 81 and the second electrode sheet 82 are each made of an acrylic resin, for example. The touch panel electrodes 86, 87 are each made of an indium tin oxide, zinc oxide, or the like, for example.

[0058] The display 9 is plate-shaped. The display 9 is, for example, a liquid crystal display or an organic EL display. The display 9 has an upper main surface and a lower main surface arranged in this order along a downward direction. The upper and lower main surfaces of the display 9 are each rectangular, having front and rear sides extending in the left-right direction and left and right sides extending in the front-to-back direction. In this modification, the upper main surface of the display 9 is attached to the lower main surface of the second electrode sheet 82 by an adhesive member (not shown). This allows the user to view the image displayed on the display 9 through the surface panel 7 and the touch sensor 8. Note that in this modification, the lower main surface of the display 9 corresponds to the lower main surface DS6 of the touch panel 6. However, the configuration of the touch panel according to the present invention is not limited to the touch panel 6.

[0059] In this modification, the deformation detection sensor 1a is attached to the lower main surface of the display 9 so that the upper main surface US2 of the piezoelectric film 2 faces the lower main surface DS6. As a result, in the electronic device 20, the touch panel 6, any one of the detection electrodes 3a to 3f, the piezoelectric film 2, and the reference electrode 4 are aligned in this order along the downward direction. On the other hand, the deformation detection sensor 1a may also be attached to the lower main surface of the display 9 so that the lower main surface DS2 of the piezoelectric film 2 faces the lower main surface DS6. In this case, in the electronic device 20, the touch panel 6, the reference electrode 4, the piezoelectric film 2, and any one of the detection electrodes 3a to 3f are aligned in this order along the downward direction.

[0060] Here, the shape and arrangement of the detection electrodes 3d and 3e will be described in detail as an example of two adjacent detection electrodes among the detection electrodes 3a to 3f.

[0061] As shown in FIG. 12 , when viewed from below, the detection electrode 3d includes a wavy first wavy portion PW1. In this modification, the entire detection electrode 3d is wavy when viewed from below. Furthermore, when viewed from below, the detection electrode 3e includes a wavy second wavy portion PW2. In this modification, the entire detection electrode 3e is wavy when viewed from below. Note that, in a wavy wavy portion, the outer edge of the wavy portion may be curved, or, as in this modification, the outer edge of the wavy portion may be a broken line. The first wavy portion PW1 and the second wavy portion PW2 face each other. When viewed from below, the first recess O1 and the first protrusion T1 face each other. Note that, when viewed from below, the entire detection electrode 3d and the entire detection electrode 3e do not necessarily have to be wavy.

[0062] 13 , when viewed from below, the outer edge OE3d of the detection electrode 3d is aligned along at least a portion of the outer edges of the touch panel electrodes 86 and 87. Similarly, when viewed from below, the outer edges OE3a to OE3c, OE3e, and OE3f of the detection electrodes 3a to 3c, 3e, and 3f are aligned along at least a portion of the outer edges of the touch panel electrodes 86 and 87, respectively. It is sufficient that at least one of the outer edges OE3a to OE3f of the detection electrodes 3a to 3f is aligned along at least a portion of the outer edge of at least one of the touch panel electrodes 86 and 87.

[0063] In the deformation detection sensor 1a as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a to 3f, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as both ends, there is no imaginary line segment IL that does not pass through any of the detection electrodes 3a to 3f. Therefore, in the deformation detection sensor 1a as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0064] Furthermore, according to the electronic device 20, when viewed from below, at least one of the outer edges OE3a to OE3f of the detection electrodes 3a to 3f is aligned along at least a portion of the outer edge of at least one of the touch panel electrodes 86, 87, making it easier to align the wiring connected to at least one of the detection electrodes 3a to 3f along at least a portion of the outer edge of at least one of the touch panel electrodes 86, 87, and making the wiring less visible from above the surface panel 7.

[0065] [Second Modification] A deformation detection sensor 1b according to a second modification of the present invention will be described below with reference to the drawings. FIG. 14 is a plan view of the deformation detection sensor 1b. FIG. 15 is a plan view of the detection electrode 3e. FIG. 16 is a plan view of the detection electrode 3e and the reinforcing electrode 10g. FIG. 17 is a model diagram of the deformation detection sensor 1b. Note that in FIG. 17, reference symbols are assigned only to representative detection electrodes 3a, reinforcing electrodes 10a, and switching elements 11e, respectively, among the detection electrodes 3a to 3i, reinforcing electrodes 10a to 10p, and switching elements 11e to 11g, 11i to 11k, and 11m to 11o. Regarding the deformation detection sensor 1b, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0066] 14, the deformation detection sensor 1b differs from the deformation detection sensor 1 in that it further includes reinforcing electrodes 10a to 10p and switching elements 11e to 11g, 11i to 11k, and 11m to 11o. The number of reinforcing electrodes is not limited to 16.

[0067] Each of the reinforcing electrodes 10a to 10p is electrically conductive. The material of each of the reinforcing electrodes 10a to 10p is, for example, copper. Each of the reinforcing electrodes 10a to 10p is flat. Each of the reinforcing electrodes 10a to 10p is harder than the piezoelectric film 2. Each of the reinforcing electrodes 10a to 10p is provided on the upper principal surface US2. More specifically, the reinforcing electrodes 10a to 10p are provided on the upper principal surface US2 at intervals from each other in the left-right direction and the front-back direction and are electrically independent from each other. Each of the reinforcing electrodes 10a to 10p is fixed to the upper principal surface US2, for example, with insulating double-sided tape (not shown). This electrically insulates each of the reinforcing electrodes 10a to 10p from the piezoelectric film 2. Therefore, each of the reinforcing electrodes 10a to 10p does not function as an electrode for outputting the potential difference generated by the piezoelectric film 2 as an electric charge. That is, each of the reinforcing electrodes 10a to 10p is different from the detection electrodes 3a to 3i. Note that each of the reinforcing electrodes 10a to 10p does not have to be in the form of a flat film. Also, each of the reinforcing electrodes 10a to 10p does not have to be harder than the piezoelectric film 2. In this modification, the detection electrodes 3a to 3i and the reinforcing electrodes 10a to 10p correspond to the first principal surface electrodes according to the present invention. Note that it is not necessary for all of the first principal surface electrodes according to the present invention to be detection electrodes; as in this modification, it is sufficient that at least one of the first principal surface electrodes is a detection electrode.

[0068] The reinforcing electrodes 10a to 10p are arranged in a matrix of four rows and four columns. The reinforcing electrodes 10a to 10d are arranged at equal intervals along the rightward direction. Similarly, the reinforcing electrodes 10e to 10h are arranged at equal intervals along the rightward direction. The reinforcing electrodes 10i to 10l are arranged at equal intervals along the rightward direction. The reinforcing electrodes 10m to 10p are arranged at equal intervals along the rightward direction. Furthermore, the reinforcing electrodes 10a, 10e, 10i, and 10m are arranged at equal intervals along the rearward direction. Similarly, the reinforcing electrodes 10b, 10f, 10j, and 10n are arranged at equal intervals along the rearward direction. The reinforcing electrodes 10c, 10g, 10k, and 10o are arranged at equal intervals along the rearward direction. The reinforcing electrodes 10d, 10h, 10l, and 10p are arranged at equal intervals along the rearward direction. The reinforcing electrodes 10a to 10p do not have to be arranged in a matrix.

[0069] When viewed from below, reinforcing electrode 10f is located between detection electrodes 3a and 3e and between detection electrodes 3b and 3d. Similarly, when viewed from below, reinforcing electrode 10g is located between detection electrodes 3b and 3f and between detection electrodes 3c and 3e. When viewed from below, reinforcing electrode 10j is located between detection electrodes 3d and 3h and between detection electrodes 3e and 3g. When viewed from below, reinforcing electrode 10k is located between detection electrodes 3e and 3i and between detection electrodes 3f and 3h.

[0070] When viewed from below, the reinforcing electrodes 10a to 10p are each rectangular with a right front edge and a left rear edge extending in a right-rear direction, and a left front edge and a right rear edge extending in a left-rear direction. Note that the shape and arrangement of the reinforcing electrodes according to the present invention are not limited to the shape and arrangement of the reinforcing electrodes 10a to 10p.

[0071] The shapes of the detection electrodes 3a to 3i of the deformation detection sensor 1b are different from the shapes of the detection electrodes 3a to 3i of the deformation detection sensor 1. However, in this modification, the detection electrodes 3a to 3i are congruent with one another when viewed from below. More specifically, when viewed from below, translating the detection electrode 3a allows it to overlap with each of the detection electrodes 3b to 3i.

[0072] As shown in Fig. 15, when viewed from below, the shape of the detection electrode 3e is a rectangle VR2 in which at least one of the four vertices V1 to V4 is cut out by a cutout area CA. More specifically, the shape of the detection electrode 3e is a rectangle VR2 in which all of the four vertices V1 to V4 are cut out by cutout areas CA1 to CA4, respectively. As a result, when viewed from below, the detection electrode 3e has an octagonal shape. However, when viewed from below, the detection electrode 3e does not have to have an octagonal shape.

[0073] Rectangle VR2 has sides S5 to S8. Sides S5 and S7 each extend in the front-to-rear direction. Side S5 is located to the right of side S7. Sides S6 and S8 each extend in the left-to-right direction. Side S6 is located in front of side S8. Sides S5 and S6 are cut out by cutout area CA1. Side S5 corresponds to the third side according to the present invention. However, the third side according to the present invention is not limited to side S5. In this modified example, cutout area CA2 has a shape that is bilaterally symmetrical with cutout area CA1, so a description thereof will be omitted. Furthermore, cutout area CA3 has a shape that is bilaterally symmetrical with cutout area CA1, so a description thereof will be omitted. Furthermore, cutout area CA4 has a shape that is point-symmetrical with cutout area CA1, so a description thereof will be omitted. However, the cutout areas CA2 to CA4 do not have to have a shape symmetrical to the cutout area CA1.

[0074] The cutout area CA1 has a right-angled triangular shape with a hypotenuse NS, whose two ends are a point on the side S5 and a point on the side S6. When viewed from below, the detection electrode 3e has a side S3e that completely overlaps with the hypotenuse NS, which is a portion of the outer edge of the cutout area CA1. The cutout area CA1 does not have to be a right-angled triangular shape, as long as at least one of the four vertices V1 to V4 of the rectangle VR2 is cut out. In other words, the hypotenuse NS is not limited to a line segment with one point on the side S5 and one point on the side S6 as its two ends, but may also be a curve with one point on the side S5 and one point on the side S6 as its two ends. In other words, the side S3e is not limited to a line segment, but may also be a curve.

[0075] The length LPA5 of the portion PA5 of the side S5 cut out by the cutout area CA1 is equal to or greater than ¼ and equal to or less than 1 / 2 of the length LS5 of the side S5. In this modification, the length LPA5 of the portion PA5 of the side S5 cut out by the cutout area CA1 is ¼ of the length LS5 of the side S5.

[0076] 16, when viewed from below, the side S3e of the detection electrode 3e faces at least a part of the reinforcing electrode 10g. In this modification, when viewed from below, the side S3e of the detection electrode 3e faces the left rear side of the reinforcing electrode 10g.

[0077] As shown in FIG. 14 , the switching elements 11e to 11g, 11i to 11k, and 11m to 11o are provided on the reinforcing electrodes 10e to 10g, 10i to 10k, and 10m to 10o, respectively. The switching elements 11e to 11g, 11i to 11k, and 11m to 11o are, for example, field effect transistors (FETs). The switching elements 11e to 11g, 11i to 11k, and 11m to 11o each have, for example, a gate terminal (not shown), a drain terminal (not shown), and a source terminal (not shown). The gate terminals of the switching elements 11e to 11g, 11i to 11k, and 11m to 11o are connected to a power supply circuit (not shown). When the power supply circuit outputs a voltage equal to or greater than a predetermined threshold to each gate terminal, the drain terminal and source terminal of each of the switching elements 11e to 11g, 11i to 11k, and 11m to 11o are brought into a conductive state, and when the power supply circuit outputs a voltage less than the predetermined threshold to each gate terminal, the drain terminal and source terminal of each of the switching elements 11e to 11g, 11i to 11k, and 11m to 11o are brought into a non-conductive state. The switching elements 11e to 11g, 11i to 11k, and 11m to 11o each correspond to an electrical element according to the present invention. However, the number of switching elements is not limited to nine. Furthermore, the electrical element according to the present invention is not limited to a switching element such as an FET, but may also be an electronic component such as an amplifier.

[0078] In FIG. 17 , one end of the switching element 11e is a drain terminal, and the other end of the switching element 11e is a source terminal. In this modification, the drain terminal of the switching element 11e is connected to the detection electrode 3a, and the source terminal of the switching element 11e is connected to the wiring 12. Similarly, the drain terminals of the switching elements 11f, 11g, 11i to 11k, and 11m to 11o are connected to the detection electrodes 3b to 3i, respectively, and the source terminals of the switching elements 11f, 11g, 11i to 11k, and 11m to 11o are connected to the wiring 12. The wiring 12 is connected to, for example, an arithmetic circuit (not shown). The arithmetic circuit performs a process to estimate the magnitude of the pressing force based on, for example, an input signal. Alternatively, the source terminal of the switching element 11e may be connected to the detection electrode 3a, and the drain terminal of the switching element 11e may be connected to the wiring 12.

[0079] In deformation detection sensor 1b, when viewed from below, when two opposing points on outer edge OE2 of piezoelectric film 2 are taken as both ends and an imaginary line segment passing between two adjacent detection electrodes or reinforcing electrodes among detection electrodes 3a to 3i and reinforcing electrodes 10a to 10p is considered, there is no imaginary line segment IL that does not pass through any of detection electrodes 3a to 3i and reinforcing electrodes 10a to 10p. Therefore, deformation detection sensor 1b can also prevent the deformation of piezoelectric film 2 from differing depending on the pressing location.

[0080] Furthermore, according to the deformation detection sensor 1b, by providing the switching elements 11e to 11g, 11i to 11k, and 11m to 11o on at least one of the reinforcing electrodes 10a to 10p, the circuit to which the detection electrodes 3a to 3i are connected can be made smaller.

[0081] Furthermore, in the deformation detection sensor 1b, the reinforcing electrode 10f is located between the detection electrodes 3a and 3e when viewed from below. This allows a virtual line segment il1, which has two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends and passes between the detection electrodes 3a and 3e, to pass through the reinforcing electrode 10f, regardless of the shapes of the detection electrodes 3a and 3e. Furthermore, the reinforcing electrode 10f is located between the detection electrodes 3b and 3d. This allows a virtual line segment il1, which has two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends and passes between the detection electrodes 3b and 3d, to pass through the reinforcing electrode 10f, regardless of the shapes of the detection electrodes 3b and 3d.

[0082] Furthermore, deformation detection sensor 1b can further suppress variations in the deformation of piezoelectric film 2 due to differences in the location of pressure. More specifically, when viewed from below, side S3e of detection electrode 3e faces at least a portion of reinforcing electrode 10g. Reinforcing electrode 10g can be made larger by setting the length LPA5 of portion PA5 of side S5 cut out by cutout area CA1 to between ¼ and 1 / 2 the length LS5 of side S5. Similar to detection electrodes 3a to 3i, reinforcing electrodes 10a to 10p suppress deformation of only a portion of piezoelectric film 2 when a user presses a point on non-electrode portion 5 downward. Therefore, the larger reinforcing electrode 10g, the more effectively it can suppress variations in the deformation of piezoelectric film 2 due to differences in the location of pressure.

[0083] [Third Modification] A deformation detection sensor 1c according to a third modification of the present invention will be described below with reference to the drawings. Fig. 18 is a plan view of the deformation detection sensor 1c. Note that in Fig. 18, only the representative detection electrode 3a among the detection electrodes 3a to 3i is designated by a reference symbol. Regarding the deformation detection sensor 1c, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0084] 18, deformation detection sensor 1c differs from deformation detection sensor 1 in the shapes of detection electrodes 3a to 3i. In this modification, detection electrodes 3a to 3i are also congruent with one another when viewed from below. More specifically, when viewed from below, detection electrode 3a can be moved in parallel to overlap with each of detection electrodes 3b to 3i.

[0085] In the deformation detection sensor 1c as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a to 3i, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as both ends, there is no imaginary line segment IL that does not pass through any of the detection electrodes 3a to 3i. Therefore, in the deformation detection sensor 1c as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0086] [Fourth Modification] A deformation detection sensor 1d according to a fourth modification of the present invention will be described below with reference to the drawings. Fig. 19 is a plan view of the deformation detection sensor 1d. Note that in Fig. 19, only the representative detection electrode 3a among the detection electrodes 3a to 3i is designated by a reference symbol. Regarding the deformation detection sensor 1d, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0087] 19, deformation detection sensor 1d differs from deformation detection sensor 1 in the shapes of detection electrodes 3a to 3i. In this modification, detection electrodes 3a to 3i are also congruent with one another when viewed from below. More specifically, when viewed from below, detection electrode 3a can be moved in parallel to overlap with each of detection electrodes 3b to 3i.

[0088] In the deformation detection sensor 1d as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a to 3i, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as both ends, there is no imaginary line segment IL that does not pass through any of the detection electrodes 3a to 3i. Therefore, in the deformation detection sensor 1d as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0089] [Fifth Modification] A deformation detection sensor 1e according to a fifth modification of the present invention will be described below with reference to the drawings. Fig. 20 is a plan view of the deformation detection sensor 1e. Note that in Fig. 20, only the representative detection electrode 3a among the detection electrodes 3a to 3i is designated by a reference symbol. Regarding the deformation detection sensor 1e, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0090] 20, deformation detection sensor 1e differs from deformation detection sensor 1 in the shapes of detection electrodes 3a to 3i. In this modification, detection electrodes 3a to 3i are also congruent with one another when viewed from below. More specifically, when viewed from below, detection electrode 3a can be moved in parallel to overlap with each of detection electrodes 3b to 3i.

[0091] In deformation detection sensor 1e as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a to 3i, with two opposing points on outer edge OE2 of piezoelectric film 2 as both ends, there is no imaginary line segment IL that does not pass through any of detection electrodes 3a to 3i. Therefore, deformation detection sensor 1e can also prevent the deformation of piezoelectric film 2 from varying depending on the pressing location.

[0092] [Sixth Modification] A deformation detection sensor 1f according to a sixth modification of the present invention will be described below with reference to the drawings. Fig. 21 is a plan view of the deformation detection sensor 1f. Note that with regard to the deformation detection sensor 1f, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0093] 21 , deformation detection sensor 1f differs from deformation detection sensor 1 in that it has ten detection electrodes and in the shapes of detection electrodes 3a to 3j. In this modification, detection electrodes 3a to 3j are also congruent with one another when viewed from below. More specifically, when viewed from below, detection electrode 3a can be moved in parallel to overlap with each of detection electrodes 3b to 3j.

[0094] In the deformation detection sensor 1f as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a to 3j, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends, there is no imaginary line segment IL that does not pass through any of the detection electrodes 3a to 3j. Therefore, in the deformation detection sensor 1f as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0095] [Seventh Modification] A deformation detection sensor 1g according to a seventh modification of the present invention will be described below with reference to the drawings. Fig. 22 is a plan view of the deformation detection sensor 1g. Note that with regard to the deformation detection sensor 1g, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0096] As shown in Fig. 22, the deformation detection sensor 1g differs from the deformation detection sensor 1 in that the number of detection electrodes is two and the shapes of the detection electrodes 3a and 3b. In this modification, the detection electrodes 3a and 3b are not congruent when viewed from below. Also, the areas of the detection electrodes 3a and 3b are different when viewed from below. The detection electrodes 3a and 3b are aligned in the rearward direction.

[0097] In the deformation detection sensor 1g as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a, 3b, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as its both ends, there is no imaginary line segment IL that does not pass through either of the detection electrodes 3a, 3b. Therefore, in the deformation detection sensor 1g as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0098] [Eighth Modification] A deformation detection sensor 1h according to an eighth modification of the present invention will be described below with reference to the drawings. Fig. 23 is a plan view of the deformation detection sensor 1h. Note that with regard to the deformation detection sensor 1h, only the differences from the deformation detection sensor 1 will be described, and the rest will be omitted.

[0099] As shown in FIG. 23 , deformation detection sensor 1h differs from deformation detection sensor 1 in that the number of detection electrodes is six and in the shapes of detection electrodes 3a to 3f. In this modification, detection electrodes 3a, 3c, and 3e are congruent with one another when viewed from below. Furthermore, detection electrodes 3b, 3d, and 3f are congruent with one another when viewed from below. When viewed from below, detection electrodes 3a, 3c, and 3e are not congruent with detection electrodes 3a, 3c, and 3e. Furthermore, when viewed from below, the areas of detection electrodes 3a, 3c, and 3e are different from the areas of detection electrodes 3a, 3c, and 3e. The detection electrodes 3a to 3f are arranged in a matrix of two rows and three columns. Note that the detection electrodes 3a to 3f do not have to be arranged in a matrix.

[0100] In the deformation detection sensor 1h as well, when viewed from below, if an imaginary line segment is considered that passes between two adjacent detection electrodes 3a to 3f, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as both ends, there is no imaginary line segment IL that does not pass through any of the detection electrodes 3a to 3f. Therefore, in the deformation detection sensor 1h as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0101] [Ninth Modification] A deformation detection sensor 1i according to a ninth modification of the present invention will be described below with reference to the drawings. Fig. 24 is a plan view of the deformation detection sensor 1i. Note that, regarding the deformation detection sensor 1i, only the differences from the deformation detection sensor 1b will be described, and the rest will be omitted.

[0102] As shown in FIG. 24, the deformation detection sensor 1i differs from the deformation detection sensor 1b in that the number of detection electrodes and reinforcing electrodes is one, and in the shapes and arrangements of the detection electrodes 3a and reinforcing electrodes 10a.

[0103] In the deformation detection sensor 1i as well, when viewed from below, if an imaginary line segment is considered that passes between the detection electrode 3a and the reinforcing electrode 10a, with two opposing points on the outer edge OE2 of the piezoelectric film 2 as its two ends, there is no imaginary line segment IL that does not pass through either the detection electrode 3a or the reinforcing electrode 10a. Therefore, in the deformation detection sensor 1i as well, it is possible to prevent the deformation of the piezoelectric film 2 from varying depending on the pressing location.

[0104] Other Embodiments The deformation detection sensor according to the present invention is not limited to the deformation detection sensors 1, 1a to 1i, and can be modified within the scope of the gist. In addition, the structures of the deformation detection sensors 1, 1a to 1i may be combined arbitrarily.

[0105] The outer edge OE2 of the piezoelectric film 2 when viewed from below is not limited to a rectangular shape, but may be a polygonal or elliptical shape.

[0106] The film according to the present invention is not limited to the piezoelectric film 2, but may be any film whose electrical properties change with deformation. An example of a film whose electrical properties change with deformation is a flat strain gauge. The electrical resistance value of a strain gauge changes with deformation. That is, the electrical properties of a strain gauge change with deformation.

[0107] The detection electrodes according to the present invention are not limited to the detection electrodes 3a to 3j, but may be any electrodes that output a change in electrical characteristics due to deformation as an electrical signal.

[0108] The present invention has the following configuration.

[0109] (1) A deformation detection sensor comprising: a flexible film whose electrical characteristics change with deformation, the film having a first main surface and a second main surface opposite the first main surface; and a plurality of first main surface electrodes provided on the first main surface, arranged at intervals along the planar direction of the first main surface, and electrically independent from one another; at least one of the plurality of first main surface electrodes is a detection electrode that outputs a change in the electrical characteristics as an electrical signal; and when imaginary line segments that pass between two adjacent first main surface electrodes among the plurality of first main surface electrodes, with two opposing points on the outer edge of the film as both ends in a planar view, do not exist that do not pass through any of the plurality of first main surface electrodes.

[0110] (2) The deformation detection sensor according to (1), wherein the detection electrode has adjacent first and second detection electrodes, the first detection electrode includes a first convex portion protruding in a first direction from the first detection electrode toward the second detection electrode, and the second detection electrode includes a first concave portion recessed in the first direction, and the first convex portion and the first concave portion face each other in a planar view.

[0111] (3) The deformation detection sensor according to (2), wherein, in a plan view, the first detection electrode has a shape in which the first convex portion is provided on at least one of four sides of a rectangle, and when the side of the rectangle on which the first convex portion is provided is defined as a first side, the first convex portion protrudes from the first side in the first direction, and the length of the portion where the first side and the first convex portion contact each other is greater than or equal to 1 / 4 and less than 1 / 2 of the length of the first side.

[0112] (4) The deformation detection sensor according to (3), wherein the detection electrode further includes a third detection electrode, the first detection electrode is adjacent to the third detection electrode, the third detection electrode includes a second protrusion protruding in a second direction from the third detection electrode toward the first detection electrode, and the first detection electrode has a shape in which, in a plan view, at least one of the sides on which the first protrusion is not provided has a second recess that is recessed in the second direction and faces the second protrusion, and when the side of the rectangle on which the second recess is provided is defined as a second side, the second recess is recessed in the second direction from the second side, and a length of a portion where the second side and the second recess meet is equal to or greater than ¼ and equal to 1 / 2 of the length of the second side.

[0113] (5) The deformation detection sensor according to any one of (1) to (4), wherein the number of the detection electrodes includes adjacent first detection electrodes and second detection electrodes, the first detection electrodes include a wavy first wave portion in plan view, the second detection electrodes include a wavy second wave portion in plan view, and the first wave portion and the second wave portion face each other in plan view.

[0114] (6) The deformation detection sensor according to any one of (1) to (5), wherein the number of the detection electrodes is plural, and the areas of the plurality of detection electrodes are equal to each other in a plan view.

[0115] (7) The deformation detection sensor according to any one of (1) to (6), wherein the number of the detection electrodes is plural, and the plurality of detection electrodes are congruent with one another in a plan view.

[0116] (8) The deformation detection sensor according to any one of (1) to (7), wherein at least one of the plurality of first principal surface electrodes is a reinforcing electrode different from the detection electrode.

[0117] (9) The deformation detection sensor according to (8), further comprising an electric element provided on at least one of the reinforcing electrodes.

[0118] (10) The deformation detection sensor according to (8) or (9), wherein the number of the detection electrodes is plural, and the reinforcing electrode is located between the plurality of detection electrodes in a plan view.

[0119] (11) The deformation detection sensor according to any one of (8) to (10), wherein, in a plan view, the detection electrode has a shape in which at least one of four vertices of a rectangle is cut out by a cutout region, and, in a plan view, a side of the detection electrode that completely overlaps with a portion of an outer edge of the cutout region faces at least a portion of the reinforcing electrode, and, when one of the sides of the rectangle that is cut out by the cutout region is defined as a third side, the length of the portion of the third side that is cut out by the cutout region is between 1 / 4 and 1 / 2 of the length of the third side.

[0120] (12) The deformation detection sensor according to any one of (1) to (11), wherein the film includes a piezoelectric film that generates a potential difference between the first principal surface and the second principal surface when deformed.

[0121] (13) The deformation detection sensor according to any one of (1) to (12), further including a second principal surface electrode provided on the second principal surface, wherein the second principal surface electrode covers substantially the entire second principal surface.

[0122] (14) An electronic device comprising: the deformation detection sensor according to (5); and a touch panel including a plurality of touch panel electrodes, wherein the touch panel has a third main surface that is pressed by a user and a fourth main surface that faces the third main surface, the deformation detection sensor is attached to the touch panel so that the first main surface or the second main surface faces the fourth main surface, and an outer edge of the detection electrode is aligned along at least a portion of an outer edge of at least one of the plurality of touch panel electrodes in a plan view.

[0123] 1, 1a to 1i: deformation detection sensor 2: piezoelectric film 3a to 3j: detection electrode 4: reference electrode 5: electrode-free portion 6: touch panel 7: surface panel 8: touch sensor 9: display 10a to 10p: reinforcing electrodes 11e to 11g, 11i, 11j, 11k: switching element 12: wiring 20: electronic device 81: first electrode sheet 82: second electrode sheet 86, 87: touch panel electrode CA, CA1 to CA4: cutout area DS2, DS6: lower main surface IL, il1, ILa to ILd: imaginary line segment NS: oblique side O1: first recess O2: second recess OE2, OE3a, OE3d: outer edge PA1, PA2, PA5: portion PW1: first wavy portion PW2: second wavy portion S1 to S3, S3e, S4 to S8: Sides T1: First convex portion T2: Second convex portion US2, US6: Upper principal surface V1 to V4: Vertices VR1, VR2: Rectangle

Claims

1. A deformation detection sensor comprising: a flexible film whose electrical properties change with deformation, the film having a first main surface and a second main surface opposite the first main surface; and a plurality of first main surface electrodes provided on the first main surface, arranged at intervals along the planar direction of the first main surface, and electrically independent from one another; at least one of the plurality of first main surface electrodes is a detection electrode that outputs a change in the electrical properties as an electrical signal; and when an imaginary line segment passing between two adjacent first main surface electrodes among the plurality of first main surface electrodes, with two opposing points on the outer edge of the film as both ends in a planar view, does not exist that does not pass through any of the plurality of first main surface electrodes.

2. The deformation detection sensor according to claim 1, wherein the detection electrode has adjacent first and second detection electrodes, the first detection electrode includes a first convex portion protruding in a first direction from the first detection electrode toward the second detection electrode, and the second detection electrode includes a first concave portion recessed in the first direction, and the first convex portion and the first concave portion face each other in a plan view.

3. The deformation detection sensor according to claim 2, wherein, in a plan view, the first detection electrode has a shape in which the first convex portion is provided on at least one of four sides of a rectangle, and when the side of the rectangle on which the first convex portion is provided is defined as a first side, the first convex portion protrudes from the first side in the first direction, and the length of the portion where the first side and the first convex portion contact each other is between 1 / 4 and 1 / 2 of the length of the first side.

4. The deformation detection sensor according to claim 3, wherein the detection electrode further includes a third detection electrode, the first detection electrode is adjacent to the third detection electrode, the third detection electrode includes a second convex portion protruding in a second direction from the third detection electrode toward the first detection electrode, the shape of the first detection electrode in a plan view is such that at least one of the sides on which the first convex portion is not provided has a second concave portion that is recessed in the second direction and faces the second convex portion, when the side of the rectangle on which the second concave portion is provided is defined as a second side, the second concave portion is recessed from the second side in the second direction, and the length of the portion where the second side and the second concave portion meet is between 1 / 4 and 1 / 2 of the length of the second side.

5. A deformation detection sensor as described in any one of claims 1 to 4, wherein the number of detection electrodes includes adjacent first detection electrodes and second detection electrodes, the first detection electrodes include a wavy first wave portion in plan view, the second detection electrodes include a wavy second wave portion in plan view, and the first wave portion and the second wave portion face each other in plan view.

6. A deformation detection sensor according to any one of claims 1 to 5, wherein the number of the detection electrodes is plural, and the areas of the plurality of detection electrodes are equal to each other in a plan view.

7. The deformation detection sensor according to any one of claims 1 to 6, wherein the number of the detection electrodes is plural, and the plurality of detection electrodes are congruent with one another in a plan view.

8. The deformation detection sensor according to any one of claims 1 to 7, wherein at least one of the plurality of first principal surface electrodes is a reinforcing electrode different from the detection electrode.

9. The deformation detection sensor according to claim 8, further comprising an electrical element provided on at least one of the reinforcing electrodes.

10. The deformation detection sensor according to claim 8 or claim 9, wherein the number of the detection electrodes is plural, and the reinforcing electrode is located between the plurality of detection electrodes in a plan view.

11. A deformation detection sensor as described in any of claims 8 to 10, wherein, in a plan view, the detection electrode has a rectangular shape with at least one of its four vertices cut out by a cutout region, and an edge of the detection electrode that completely overlaps with a portion of the outer edge of the cutout region in a plan view faces at least a portion of the reinforcing electrode, and when one of the edges of the rectangle that is cut out by the cutout region is designated as a third edge, the length of the portion of the third edge that is cut out by the cutout region is between 1 / 4 and 1 / 2 of the length of the third edge.

12. A deformation detection sensor according to any one of claims 1 to 11, wherein the film includes a piezoelectric film that generates a potential difference between the first principal surface and the second principal surface when deformed.

13. The deformation detection sensor according to any one of claims 1 to 12, further comprising a second principal surface electrode provided on the second principal surface, the second principal surface electrode covering substantially the entire second principal surface.

14. An electronic device comprising: a deformation detection sensor according to claim 5; and a touch panel including a plurality of touch panel electrodes, wherein the touch panel has a third main surface that is pressed by a user and a fourth main surface that faces the third main surface, the deformation detection sensor is attached to the touch panel so that the first main surface or the second main surface faces the fourth main surface, and an outer edge of the detection electrode follows at least a portion of the outer edge of at least one of the plurality of touch panel electrodes in a plan view.

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