Deformation detection sensor and electronic device

Abstract

A deformation detection sensor according to one embodiment of the present invention comprises: a holding plate that is pressed by a user; a piezoelectric film; a buffer material; and a support body that supports the holding plate, the piezoelectric film, and the buffer material and that is harder than the holding plate. The piezoelectric film is disposed between the holding plate and the buffer material, and the buffer material is disposed between the piezoelectric film and the support body.

Description

Deformation detection sensor and electronic device

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

[0002] Patent Document 1 describes an input terminal that includes a housing, a holding member, and a piezoelectric sensor. The piezoelectric sensor includes a piezoelectric film. The holding member is fixed to the outer periphery of the housing. The piezoelectric sensor is attached to the holding member. The piezoelectric sensor detects deformation of the holding member. Specifically, a user presses the holding member. The piezoelectric film of the piezoelectric sensor deforms in accordance with the deformation of the holding member. The piezoelectric film is polarized according to the amount of strain of the piezoelectric film.

[0003] International Publication No. 2016 / 027603

[0004] In the structure of the input terminal described in Patent Document 1, when a user presses the holding member, the entire holding member is deformed. In other words, the structure of the input terminal described in Patent Document 1 is not a structure in which the area pressed by the user is locally deformed. Patent Document 1 does not describe detecting local deformation of the area of ​​the holding member pressed by the user.

[0005] An object of the present invention is to provide a deformation detection sensor that can detect local deformation at a pressed location on a holding plate.

[0006] A deformation detection sensor according to one embodiment of the present invention comprises a holding plate that is pressed by a user, a piezoelectric film, a buffer material, and a support that supports the holding plate, the piezoelectric film, and the buffer material and is harder than the holding plate, wherein the piezoelectric film is disposed between the holding plate and the buffer material, and the buffer material is disposed between the piezoelectric film and the support.

[0007] The deformation detection sensor according to one embodiment of the present invention can detect local deformation at a pressed location on the holding plate.

[0008] FIG. 1 is a top view of the smartphone SP1. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIGS. 3A and 3B are diagrams illustrating deformation of the touch panel 11 when the touch panel 11 is pressed in a deformation detection sensor 1ex according to a comparative example. FIGS. 4A and 4B are diagrams illustrating deformation of the touch panel 11 when the touch panel 11 is pressed in a deformation detection sensor 1. FIG. 5 is a diagram illustrating the results of an experiment conducted to examine the amount of deformation of the piezoelectric film 120 when the center portion CE of the touch panel 11 is pressed in a deformation detection sensor 1ex according to a comparative example. FIG. 6 is a diagram illustrating the results of an experiment conducted to examine the amount of deformation of the piezoelectric film 120 when the center portion CE of the touch panel 11 is pressed in a deformation detection sensor 1. FIG. 7 is a diagram illustrating the results of an experiment conducted to examine the amount of deformation of the piezoelectric film 120 when multiple portions CL3 and CR3 of the touch panel 11 are pressed in a deformation detection sensor 1ex according to a comparative example. FIG. 8 shows the results of an experiment in which the deformation amount of the piezoelectric film 120 in the deformation detection sensor 1 was examined when multiple portions CL4 and CR4 of the touch panel 11 were pressed. FIG. 9 shows a deformation detection sensor 1a according to Modification 1 of the deformation detection sensor 1. FIG. 10 shows a deformation detection sensor 1b according to Modification 2 of the deformation detection sensor 1. FIG. 11 shows a deformation detection sensor 1c according to Modification 3 of the deformation detection sensor 1. FIG. 12 is a top view showing the piezoelectric film 120 and the buffer material 13 in a deformation detection sensor 1d according to Modification 4 of the deformation detection sensor 1. FIG. 13(A) is a top view of the piezoelectric film 120 and the buffer material 13 in a deformation detection sensor 1e according to Modification 4 of the deformation detection sensor 1. FIG. 13(B) is a top view of the piezoelectric film 120 and the buffer material 13 in a deformation detection sensor 1f according to Modification 4 of the deformation detection sensor 1. FIG. 14 shows a result D1 of an experiment using the deformation detection sensor 1e. FIG. 15 shows a result D2 of an experiment using the deformation detection sensor 1f. FIG. 16 is a diagram showing a deformation detection sensor 1 g according to a fifth modification of the deformation detection sensor 1 .

[0009] [First embodiment] A smartphone SP1 equipped with 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 top view of the smartphone SP1. In Fig. 1, the piezoelectric sensor 12 is shown in perspective with a dashed line. Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1.

[0010] The smartphone SP1 is an example of an electronic device in the present application. Note that the electronic device in the present application does not necessarily have to be a smartphone. The electronic device in the present application may be, for example, a tablet computer. The following describes the deformation detection sensor 1 in the smartphone SP1, and a description of the configuration other than the deformation detection sensor 1 is omitted.

[0011] As shown in FIGS. 1 and 2 , the deformation detection sensor 1 includes a housing 10 , a touch panel 11 , a piezoelectric sensor 12 , and a buffer material 13 .

[0012] The touch panel 11 corresponds to the holding plate in the present application. As shown in FIGS. 1 and 2 , the touch panel 11 is plate-shaped and has a first main surface SF1 that is pressed by a user and a second main surface SF2 that faces the first main surface SF1. The touch panel 11 detects a touch operation on the touch panel 11 by a user. For example, the touch panel 11 includes a surface panel and a capacitive touch sensor. The touch sensor detects whether or not a touch operation has been performed on the surface panel and the position of the touch operation. Note that the touch panel 11 does not necessarily have to include a capacitive touch sensor, and may include a resistive touch sensor or the like instead of the capacitive touch sensor.

[0013] The piezoelectric sensor 12 has a sheet shape in a plan view. The piezoelectric sensor 12 is disposed between the touch panel 11 and the buffer material 13. The piezoelectric sensor 12 is fixed to the touch panel 11 with an adhesive (not shown). As shown in Fig. 1 , the piezoelectric sensor 12 is disposed so as to overlap substantially the entire surface of the touch panel 11 in a plan view. As shown in Fig. 2 , the piezoelectric sensor 12 includes a piezoelectric film 120, a first ground electrode 121, and a signal electrode 122.

[0014] The piezoelectric film 120 is, for example, a film formed from a chiral polymer. Examples of chiral polymers include polylactic acid (PLA), particularly poly(L-lactic acid) (PLLA) or poly(D-lactic acid) (PDLA). PLA, a chiral polymer, has a helical main chain structure. The piezoelectric film 120 made of PLA has a piezoelectric constant of d14. The piezoelectric film 120 exhibits piezoelectricity by uniaxially stretching the molecules to orient them. As shown in FIG. 1 , the stretching direction OD of the piezoelectric film 120 forms a 45-degree angle with respect to the sides of the piezoelectric film 120. However, the angle between the stretching direction OD and the sides of the piezoelectric film 120 may be approximately 45 degrees ±10 degrees. The piezoelectric film 120 is polarized according to the amount of deformation of the piezoelectric film 120. The direction of polarization when the piezoelectric film 120 is stretched in the direction in which the long sides of the film 120 extend is opposite to the direction of polarization when the piezoelectric film 120 is stretched in the direction in which the short sides of the film 120 extend. Note that the above angle is an example, and the angle between the stretching direction OD and the side of the piezoelectric film 120 may be, for example, approximately 0 degrees ± 10 degrees or 90 degrees ± 10 degrees.

[0015] The first ground electrode 121 is connected to a ground potential. As shown in FIG. 2 , the first ground electrode 121 is disposed between the piezoelectric film 120 and the touch panel 11. The first ground electrode 121 is fixed to the upper surface of the piezoelectric film 120 with an adhesive (not shown). The first ground electrode 121, which is connected to the ground potential, prevents signals generated by the piezoelectric film 120 from affecting external devices as noise. The first ground electrode 121 also prevents external noise from affecting the piezoelectric sensor 12.

[0016] 2, the signal electrode 122 is disposed between the piezoelectric film 120 and the bottom of the housing 10. The signal electrode 122 is fixed to the bottom surface of the piezoelectric film 120 by an adhesive (not shown).

[0017] Alternatively, the signal electrode 122 may be fixed to the top surface of the piezoelectric film 120, and the first ground electrode 121 may be fixed to the bottom surface of the piezoelectric film 120. However, by disposing the first ground electrode 121 between the touch panel 11 and the piezoelectric film 120, it is possible to prevent the signal of the piezoelectric film 120 from affecting the touch panel 11 as noise, or prevent the signal of the touch panel 11 from affecting the piezoelectric film 120 as noise.

[0018] The piezoelectric sensor 12 detects deformation of the touch panel 11. Specifically, when a user presses the touch panel 11 toward the bottom of the housing 10, the touch panel 11 is deformed. As the touch panel 11 deforms, the piezoelectric sensor 12 arranged on the touch panel 11 is deformed. The piezoelectric sensor 12 outputs a signal corresponding to the deformation of the piezoelectric sensor 12.

[0019] The buffer material 13 is disposed between the piezoelectric sensor 12 and the bottom of the housing 10. The buffer material 13 is fixed to the piezoelectric sensor 12 and the bottom of the housing 10, for example, by an adhesive (not shown). Note that the buffer material 13 may be fixed to only one of the piezoelectric sensor 12 or the bottom of the housing 10, or may not be fixed at all.

[0020] The cushioning material 13 is a foam-molded member, and is made of, for example, a material having shape restoring properties. Specifically, the ratio of the thickness of the cushioning material 13 after it is compressed to 50% or less and then released to the thickness of the cushioning material 13 before compression is 80% or more. This allows the cushioning material 13 to easily return to its pre-compression shape when the user releases pressure on the touch panel 11. The restoring force generated when the cushioning material 13 returns to its pre-compression shape pushes up the touch panel 11. Therefore, when the user releases pressure on the touch panel 11, the touch panel 11 easily returns to its pre-deformation shape. Note that the cushioning material 13 does not necessarily have to be a foam-molded member.

[0021] It should be noted that the cushioning material 13 does not necessarily have to have shape restoring properties. The ratio of the thickness of the cushioning material 13 after it is compressed to 50% or less and then released to the thickness of the cushioning material 13 before compression may be 80% or less, for example, 50%.

[0022] The elastic modulus of the buffer material 13 is smaller than the elastic modulus of the touch panel 11. As an example, the elastic modulus of the touch panel 11 is 5 MPa or more and 10 GPa or less, and the elastic modulus of the buffer material 13 is smaller than 5 MPa. In other words, the buffer material 13 is softer and more easily deformed than the touch panel 11. Therefore, when a user presses the touch panel 11, the deformation of the touch panel 11 is not hindered by the buffer material 13. Therefore, the deformation of the piezoelectric sensor 12 arranged on the touch panel 11 is not hindered by the buffer material 13. In other words, the piezoelectric sensor 12 is more easily deformed, making it easier to detect the deformation of the touch panel 11. Note that the elastic moduli of the touch panel 11 and the buffer material 13 are not limited to the above values.

[0023] The touch panel 11 is fixed to the outer peripheral edge of the housing 10. The piezoelectric sensor 12 and the buffer material 13 are disposed inside the housing 10. The housing 10 is harder than the touch panel 11, the piezoelectric sensor 12, and the buffer material 13. When the touch panel 11 is pressed, the housing 10 supports the touch panel 11, the piezoelectric sensor 12, and the buffer material 13 without substantially deforming. The housing 10 corresponds to the support body in this application.

[0024] The ability of the deformation detection sensor 1 to detect local deformation at a pressed location will be described below by comparing a deformation detection sensor 1ex according to a comparative example with the deformation detection sensor 1. Figures 3A and 3B are diagrams showing the deformation of the touch panel 11 when the touch panel 11 is pressed by the deformation detection sensor 1ex according to the comparative example. The configuration of the deformation detection sensor 1ex is the same as that of the deformation detection sensor 1, except that it does not include the cushioning material 13. In Figures 3A and 3B, the housing 10 of the deformation detection sensor 1ex is omitted.

[0025] 3A, when a user presses the deformation detection sensor 1ex on the center portion CE of the touch panel 11 downward in the plane of the drawing, a force is generated on the center portion CE in the downward direction of the plane of the drawing, causing the center portion CE of the touch panel 11 to deform so as to bend convexly downward in the plane of the drawing.

[0026] Therefore, the entire touch panel 11 deforms so as to expand in a direction parallel to the first main surface SF1. In other words, in the deformation detection sensor 1ex, when a user presses the touch panel 11, the pressed area does not deform locally, but the entire touch panel 11 deforms so as to expand downward in the plane of the page.

[0027] 4A and 4B are diagrams showing deformation of the touch panel 11 when the touch panel 11 is pressed by the deformation detection sensor 1. In FIGS. 4A and 4B, the side surface of the housing 10 is not shown.

[0028] As shown in Fig. 4A, a user presses the center portion CE of the touch panel 11 of the deformation detection sensor 1 downward on the paper surface in Fig. 4A. In this case, a force is generated downward on the center portion CE. At this time, the center portion CE of the touch panel 11 deforms so as to bend convexly downward on the paper surface. In other words, as shown in Fig. 4B, the second main surface SF2 at the center portion CE (pressed location) stretches.

[0029] The downward pressure on the central portion CE generates a downward force on the page at a location SR around the central portion CE. The downward force on the page generated at the location SR compresses the cushioning material 13. The restoring force generated in the compressed cushioning material 13 generates an upward force on the page at the location SR. The upward force on the page generated at the location SR pushes the location SR upward. This makes it difficult for the location SR to deform so as to bend convexly downward on the page. At this time, as shown in FIG. 4B , the first main surface SF1 at the location SR (other than the pressed location) stretches.

[0030] As described above, the deformation detection sensor 1 can suppress deformation of portions other than the central portion CE when the central portion CE is pressed. That is, compared to the deformation detection sensor 1ex according to the comparative example, the entire touch panel 11 does not deform downward in the plane of the drawing, but the central portion CE deforms locally, bending convexly downward in the plane of the drawing. In other words, compared to the deformation detection sensor 1ex according to the comparative example, the structure of the deformation detection sensor 1 is such that the area pressed by the user deforms locally. Therefore, in the deformation detection sensor 1, when the piezoelectric sensor 12 detects deformation of the touch panel 11, the piezoelectric sensor 12 detects the deformation of the touch panel 11 in a state in which deformation of portions other than the pressed area of ​​the touch panel 11 is suppressed. That is, the deformation detection sensor 1 can detect deformation of the pressed area of ​​the touch panel 11 in a more localized manner.

[0031] Fig. 5 is a diagram showing the results of an experiment in which the amount of deformation of the piezoelectric film 120 when the center portion CE of the touch panel 11 is pressed in a deformation detection sensor 1ex according to a comparative example is measured. The graph on the right side of Fig. 5 shows the amount of deformation of the piezoelectric film 120 at the position indicated by the dashed line on the left side of Fig. 5. Fig. 6 is a diagram showing the results of an experiment in which the amount of deformation of the piezoelectric film 120 when the center portion CE of the touch panel 11 is pressed in a deformation detection sensor 1. The graph on the right side of Fig. 6 shows the amount of deformation of the piezoelectric film 120 at the position indicated by the dashed line on the left side of Fig. 6.

[0032] 5, when a user presses the central portion CE of the touch panel 11 with the deformation detection sensor 1ex, the entire piezoelectric film 120 deforms so as to bend convexly downward on the page from the left end L1 and the right end R1 of the piezoelectric film 120 toward the central portion CE of the piezoelectric film 120. In other words, when a user presses the central portion CE of the touch panel 11 with the deformation detection sensor 1ex, the central portion CE does not deform locally, but the entire touch panel 11 deforms so as to bend convexly downward on the page.

[0033] 6, when a user presses the central portion CE of the touch panel 11 of the deformation detection sensor 1, the central portion CE of the piezoelectric film 120 deforms so as to bend convexly downward on the page, while portions other than the central portion CE (for example, the vicinity of the left end L2 or the vicinity of the right end R2 of the piezoelectric film 120) do not deform so as to bend convexly downward on the page. In other words, in the deformation detection sensor 1, the pressed area of ​​the touch panel 11 (the central portion CE) deforms in a manner that is similar to that of the deformation detection sensor 1ex according to the comparative example.

[0034] As shown in FIG. 6, when a user presses the center portion CE of the touch panel 11 of the deformation detection sensor 1, a portion SR of the piezoelectric film 120 surrounding the center portion CE is pushed upward in the plane of the drawing.

[0035] Fig. 7 is a diagram showing the results of an experiment conducted to examine the amount of deformation of the piezoelectric film 120 when multiple portions CL3, CR3 of the touch panel 11 are pressed in a deformation detection sensor 1ex according to a comparative example. The graph on the right side of Fig. 7 shows the amount of deformation of the piezoelectric film 120 at the position of the dashed line shown on the left side of Fig. 7. Fig. 8 is a diagram showing the results of an experiment conducted to examine the amount of deformation of the piezoelectric film 120 when multiple portions CL4, CR4 of the touch panel 11 are pressed in a deformation detection sensor 1. The graph on the right side of Fig. 8 shows the amount of deformation of the piezoelectric film 120 at the position of the dashed line shown on the left side of Fig. 8.

[0036] As shown in FIG. 7, when a user presses two portions CL3 and CR3 of the touch panel 11 on the deformation detection sensor 1ex, the entire touch panel 11 is deformed so as to bend convexly downward in the plane of the drawing.

[0037] On the other hand, as shown in FIG. 8 , when a user presses two positions, CL4 and CR4, of the touch panel 11 using the deformation detection sensor 1, the positions CL4 and CR4 are each deformed so as to bend convexly downward in the plane of the drawing, but the portions other than the positions CL4 and CR4 are not deformed so as to bend convexly downward in the plane of the drawing. In other words, when multiple positions on the touch panel 11 are pressed simultaneously, each of the multiple positions deforms in a similar manner to the localized position. Therefore, the deformation detection sensor 1 can simultaneously detect the deformation of each of the multiple pressed positions. Therefore, the smartphone SP1 equipped with the deformation detection sensor 1 can realize an application that takes advantage of the simultaneous detection of multiple pressed positions.

[0038] [Modification 1] Hereinafter, a deformation detection sensor 1a according to Modification 1 of the deformation detection sensor 1 will be described with reference to the drawings. Fig. 9 is a diagram showing the deformation detection sensor 1a according to Modification 1 of the deformation detection sensor 1.

[0039] As shown in Fig. 9, the deformation detection sensor 1a differs from the deformation detection sensor 1 in that it includes an adhesive 13a having adhesive properties instead of the buffer material 13. The adhesive 13a fixes the piezoelectric sensor 12 to the bottom of the housing 10. The elastic modulus of the adhesive 13a is less than 5 MPa. Note that the elastic modulus of the adhesive 13a does not necessarily have to be less than 5 MPa. The other configurations of the deformation detection sensor 1a are the same as those of the deformation detection sensor 1, so a description thereof will be omitted.

[0040] The deformation detection sensor 1 a having the adhesive 13 a has the same effect as the deformation detection sensor 1 .

[0041] [Modification 2] Hereinafter, a deformation detection sensor 1b according to Modification 2 of the deformation detection sensor 1 will be described with reference to the drawings. Fig. 10 is a diagram showing a deformation detection sensor 1b according to Modification 2 of the deformation detection sensor 1.

[0042] The deformation detection sensor 1b differs from the deformation detection sensor 1 in that the deformation detection sensor 1b further includes a second ground electrode 14 and an adhesive 15 having adhesive properties.

[0043] The second ground electrode 14 is, for example, a conductive nonwoven fabric. Of course, the second ground electrode 14 does not necessarily have to be a conductive nonwoven fabric. As shown in FIG. 10 , the second ground electrode 14 is disposed between the signal electrode 122 and the buffer material 13. The second ground electrode 14 is connected to the ground potential. In this case, the signal electrode 122 is sandwiched between the first ground electrode 121 and the second ground electrode 14. This prevents the signal generated by the piezoelectric film 120 from affecting external devices as noise, and prevents external noise from affecting the piezoelectric sensor 12.

[0044] Furthermore, by using a highly conductive material such as Ag as the material for the first ground electrode 121 on the touch panel 11 side, the signal generated by the piezoelectric film 120 is further prevented from affecting external devices as noise, and external noise is further prevented from affecting the piezoelectric sensor 12.

[0045] The adhesive 15 is disposed between the second ground electrode 14 and the signal electrode 122. The adhesive 15 is formed of, for example, an insulating material. This prevents the second ground electrode 14 from being electrically connected to the signal electrode 122. The adhesive 15 fixes the second ground electrode 14 and the signal electrode 122 together.

[0046] In this modification, the second ground electrode 14 is disposed below the piezoelectric film 120 in Fig. 10. This positions the piezoelectric film 120 above the neutral plane (the plane where the laminate does not expand or contract when the laminate is deformed) of the laminate consisting of the piezoelectric sensor 12, the adhesive 15, and the second ground electrode 14. In other words, the piezoelectric film 120 moves away from the neutral plane. When the touch panel 11 is pressed and a force is generated in the laminate, the amount of deformation of the piezoelectric film 120 moving away from the neutral plane tends to increase. This makes it easier for the piezoelectric sensor 12 to detect deformation of the touch panel 11.

[0047] In this modification, the signal electrode 122 and the second ground electrode 14 are stretchable. The first ground electrode 121 is softer than the signal electrode 122 and the second ground electrode 14. That is, the portion of the laminate facing the touch panel 11 is soft and easily deformed. Therefore, when the touch panel 11 is pressed, the piezoelectric film 120 facing the touch panel 11 is easily deformed, and the amount of deformation is likely to be large.

[0048] The other configurations of the deformation detection sensor 1b are the same as those of the deformation detection sensor 1, and therefore, description thereof will be omitted.

[0049] [Modification 3] Hereinafter, a deformation detection sensor 1c according to Modification 3 of the deformation detection sensor 1 will be described with reference to the drawings. Fig. 11 is a diagram showing the deformation detection sensor 1c according to Modification 3 of the deformation detection sensor 1.

[0050] The arrangement of the first ground electrode 121, the signal electrode 122, and the second ground electrode 14 in the deformation detection sensor 1c is different from the arrangement of the first ground electrode 121, the signal electrode 122, and the second ground electrode 14 in the deformation detection sensor 1b.

[0051] 11 , in the deformation detection sensor 1c, the signal electrode 122 is disposed between the piezoelectric film 120 and the touch panel 11. The first ground electrode 121 is disposed between the piezoelectric film 120 and the buffer material 13. The second ground electrode 14 is disposed between the signal electrode 122 and the touch panel 11. The adhesive 15 is disposed between the signal electrode 122 and the second ground electrode 14. This prevents the signal electrode 122 from being electrically connected to the second ground electrode 14. In this modification, the signal electrode 122 and the second ground electrode 14 are fixed together by the adhesive 15. The deformation detection sensor 1c has the same effects as the deformation detection sensor 1b.

[0052] The other configurations of the deformation detection sensor 1c are the same as those of the deformation detection sensor 1b, and therefore, description thereof will be omitted.

[0053] [Modification 4] Hereinafter, a deformation detection sensor 1d according to Modification 4 of the deformation detection sensor 1 will be described with reference to the drawings. Fig. 12 is a top view showing the piezoelectric film 120 and the buffer material 13 in the deformation detection sensor 1d according to Modification 4 of the deformation detection sensor 1. In Fig. 12, description of the configuration of the deformation detection sensor 1d other than the piezoelectric film 120 and the buffer material 13 is omitted.

[0054] The size of the piezoelectric film 120 in the deformation detection sensor 1d is different from the size of the piezoelectric film 120 in the deformation detection sensor 1. As shown in Fig. 12 , in the deformation detection sensor 1d, the piezoelectric film 120 overlaps the buffer material 13 in a plan view. In this case, no matter which part of the touch panel 11 is pressed, the area around the pressed part is pushed up by the buffer material 13, causing the pressed part to deform locally. In other words, it is possible to detect local deformation of the pressed part over the entire area of ​​the touch panel 11.

[0055] Furthermore, if the piezoelectric film 120 and the buffer material 13 overlap at the pressed point, the piezoelectric sensor 12 can detect local deformation at the pressed point even if the piezoelectric film 120 and the buffer material 13 do not overlap in a portion away from the pressed point.

[0056] 13A is a top view of the piezoelectric film 120 and the buffer material 13 in a deformation detection sensor 1e according to a fourth modification of the deformation detection sensor 1. In the deformation detection sensor 1e, in a plan view, the short side of the piezoelectric film 120 overlaps the short side of the buffer material 13. The deformation detection sensor 1e has the same effect as the deformation detection sensor 1d.

[0057] 13B is a top view of the piezoelectric film 120 and the buffer material 13 in a deformation detection sensor 1f according to a fourth modification of the deformation detection sensor 1. In the deformation detection sensor 1f, in plan view, the long sides of the piezoelectric film 120 overlap the long sides of the buffer material 13. The deformation detection sensor 1f has the same effects as the deformation detection sensor 1d.

[0058] The other configurations of the deformation detection sensors 1d, 1e, and 1f are the same as the configuration of the deformation detection sensor 1, and therefore, description thereof will be omitted.

[0059] [Experiment Using Deformation Detection Sensors 1e and 1f] An experiment using the deformation detection sensors 1e and 1f will be described below with reference to the drawings. FIG. 14 shows the result D1 of an experiment using the deformation detection sensor 1e. In this experiment, the voltage distribution of the piezoelectric film 120 when a point P1 on the touch panel 11 was pressed was examined under four conditions (1) to (4) in which the short side of the piezoelectric film 120 had different lengths (see FIG. 14). The point P1 is a point on the touch panel 11 that overlaps with the vicinity of the center of the long side of the piezoelectric film 120. Under conditions (1) to (4), the long side of the piezoelectric film 120 has the same length.

[0060] 14 , under conditions (1) and (2), the length of the short side of the buffer material 13 is shorter than the length of the short side of the piezoelectric film 120. In other words, under conditions (1) and (2), in plan view, the buffer material 13 does not overlap the vicinity of the long side of the piezoelectric film 120. Therefore, as shown in FIG. 14 , under conditions (1) and (2), when position P1 is pressed, the entire vicinity of the long side of the piezoelectric film 120 is deformed. In other words, under conditions (1) and (2), the pressed position P1 on the touch panel 11 is not locally deformed.

[0061] On the other hand, under conditions (3) and (4) in Fig. 14 , the length of the short side of the buffer material 13 is longer than or equal to the length of the short side of the piezoelectric film 120. That is, under conditions (3) and (4), in a plan view, the buffer material 13 overlaps the vicinity of the long side of the piezoelectric film 120. Therefore, as shown in Fig. 14 , under conditions (3) and (4), when point P1 is pressed, the portion of the piezoelectric film 120 that overlaps with point P1 is deformed in a nearly localized manner. That is, under conditions (3) and (4), the pressed point P1 on the touch panel 11 is deformed in a nearly localized manner.

[0062] Fig. 15 shows the result D2 of an experiment using the deformation detection sensor 1f. In this experiment, the voltage distribution of the piezoelectric film 120 when point P2 of the touch panel 11 was pressed was examined under four conditions (5) to (8) in which the long side of the piezoelectric film 120 had different lengths (see Fig. 15). Point P2 is a point on the touch panel 11 that overlaps with the vicinity of the center of the short side of the piezoelectric film 120. Under conditions (5) to (8), the short side of the piezoelectric film 120 has the same length.

[0063] 15 , under conditions (5) and (6), the length of the long side of the buffer material 13 is shorter than the length of the long side of the piezoelectric film 120. In other words, under conditions (5) and (6), in a plan view, the buffer material 13 does not overlap the vicinity of the short side of the piezoelectric film 120. Therefore, as shown in FIG. 15 , under conditions (5) and (6), when position P2 is pressed, the entire vicinity of the short side of the piezoelectric film 120 is deformed. In other words, under conditions (5) and (6), the pressed position P2 on the touch panel 11 is not locally deformed.

[0064] On the other hand, under conditions (7) and (8) in Fig. 15 , the length of the long side of the buffer material 13 is longer than or equal to the length of the long side of the piezoelectric film 120. That is, under conditions (7) and (8), in plan view, the buffer material 13 overlaps the vicinity of the short side of the piezoelectric film 120. Therefore, as shown in Fig. 15 , under conditions (7) and (8), when point P2 is pressed, the portion of the piezoelectric film 120 that overlaps with point P2 is deformed in a nearly localized manner. That is, under conditions (7) and (8), the pressed point P2 on the touch panel 11 is deformed in a nearly localized manner.

[0065] [Modification 5] Hereinafter, a deformation detection sensor 1g according to Modification 5 of the deformation detection sensor 1 will be described with reference to the drawings. Fig. 16 is a diagram showing a deformation detection sensor 1g according to Modification 5 of the deformation detection sensor 1.

[0066] 16 , the deformation detection sensor 1g differs from the deformation detection sensor 1 in that the piezoelectric sensor 12 is disposed on a liquid crystal display 16 of the smartphone SP1. In this modification, the liquid crystal display 16 is part of the configuration of the deformation detection sensor of the present application. The liquid crystal display 16 corresponds to the holding plate of the present application.

[0067] The liquid crystal display 16 is disposed between the touch panel 11 and the piezoelectric sensor 12. In this modification, the liquid crystal display 16 is deformed when the touch panel 11 is pressed. The deformation of the liquid crystal display 16 deforms the piezoelectric sensor 12 disposed on the liquid crystal display 16. The deformation detection sensor 1g has the same effect as the deformation detection sensor 1.

[0068] The smartphone SP1 may include an organic EL display instead of the liquid crystal display 16. In this case, the piezoelectric sensor 12 is disposed on the organic EL display. The organic EL display corresponds to the holding plate in this application.

[0069] The smartphone SP1 does not necessarily have to include the touch panel 11 and the liquid crystal display 16 separately. For example, the smartphone SP1 may include a liquid crystal display with a touch panel or an organic EL display with a touch panel instead of the touch panel 11 and the liquid crystal display 16 separately. The piezoelectric sensor 12 is disposed on the liquid crystal display with a touch panel or the organic EL display with a touch panel. In this case, the liquid crystal display with a touch panel or the organic EL display with a touch panel corresponds to the holding plate in this application.

[0070] [Other Embodiments] The description of the present embodiment should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above-described embodiments. Furthermore, the scope of the present invention includes the scope equivalent to the claims.

[0071] The deformation detection sensor according to the present invention is not limited to the deformation detection sensors 1, 1a to 1g, and can be modified within the scope of the invention. The configurations of the deformation detection sensors 1, 1a to 1g may be combined arbitrarily.

[0072] The smartphone SP1 in the present application may include deformation detection sensors 1a to 1g instead of the deformation detection sensor 1.

[0073] The present invention has the following structure:

[0074] (1) A deformation detection sensor comprising: a holding plate pressed by a user; a piezoelectric film; a buffer material; and a support body that supports the holding plate, the piezoelectric film, and the buffer material and is harder than the holding plate, wherein the piezoelectric film is disposed between the holding plate and the buffer material, and the buffer material is disposed between the piezoelectric film and the support body.

[0075] (2) The deformation detection sensor according to (1), wherein the ratio of the thickness of the buffer material after being compressed to 50% or less and released to the thickness of the buffer material before compression is 80% or more.

[0076] (3) The deformation detection sensor according to (1) or (2), wherein the elastic modulus of the buffer material is smaller than the elastic modulus of the holding plate.

[0077] (4) The deformation detection sensor according to (3), wherein the elastic modulus of the holding plate is 5 MPa or more and 10 GPa or less, and the elastic modulus of the buffer material is less than 5 MPa.

[0078] (5) The deformation detection sensor according to any one of (1) to (4), wherein the buffer material is an adhesive having adhesiveness.

[0079] (6) The deformation detection sensor according to (5), wherein the buffer material has an elastic modulus of less than 5 MPa.

[0080] (7) The deformation detection sensor according to any one of (1) to (6), wherein the piezoelectric film overlaps the buffer material in a plan view.

[0081] (8) The deformation detection sensor according to any one of (1) to (7), further comprising: a first ground electrode disposed between the piezoelectric film and the holding plate; and a signal electrode disposed between the piezoelectric film and the buffer material.

[0082] (9) The deformation detection sensor according to (8), further comprising a second ground electrode disposed between the signal electrode and the buffer material, wherein the signal electrode and the second ground electrode are stretchable, and the first ground electrode is softer than the signal electrode and the second ground electrode.

[0083] (10) The deformation detection sensor described in any one of (1) to (7), further comprising: a signal electrode disposed between the piezoelectric film and the holding plate; a first ground electrode disposed between the piezoelectric film and the buffer material; and a second ground electrode disposed between the signal electrode and the holding plate, wherein the signal electrode and the second ground electrode are stretchable, and the first ground electrode is softer than the signal electrode and the second ground electrode.

[0084] (11) The deformation detection sensor according to any one of (1) to (10), wherein the orientation direction of the piezoelectric film forms an angle of 45 degrees with respect to a side of the piezoelectric film.

[0085] (12) The deformation detection sensor according to any one of (1) to (11), wherein the holding plate has a first main surface that is pressed by the user and a second main surface that faces the first main surface, and when the holding plate is pressed, the second main surface extends at the pressed location, and the first main surface extends at a location other than the pressed location.

[0086] (13) An electronic device including the deformation detection sensor according to any one of (1) to (12), wherein the holding plate is any one of a touch panel, a liquid crystal display, an organic EL display, a liquid crystal display with a touch panel, and an organic EL display with a touch panel.

[0087] 1 to 1g: Deformation detection sensor 10: Housing 11: Touch panel 12: Piezoelectric sensor 120: Piezoelectric film 121: First ground electrode 122: Signal electrode 13: Cushioning material 13a, 15: Adhesive 14: Second ground electrode 16: Liquid crystal display SP1: Smartphone

Claims

1. A deformation detection sensor comprising: a holding plate pressed by a user; a piezoelectric film; a cushioning material; and a support body that supports the holding plate, the piezoelectric film, and the cushioning material and is harder than the holding plate, wherein the piezoelectric film is disposed between the holding plate and the cushioning material, and the cushioning material is disposed between the piezoelectric film and the support body.

2. The deformation detection sensor according to claim 1, wherein a ratio of the thickness of the cushioning material after it is compressed to 50% or less and then released to the thickness of the cushioning material before compression is 80% or more.

3. The deformation detection sensor according to claim 1 or 2, wherein the elastic modulus of the buffer material is smaller than the elastic modulus of the holding plate.

4. The deformation detection sensor according to claim 3, wherein the elastic modulus of the retaining plate is 5 MPa or more and 10 GPa or less, and the elastic modulus of the buffer material is less than 5 MPa.

5. The deformation detection sensor according to any one of claims 1 to 4, wherein the cushioning material is an adhesive having adhesive properties.

6. The deformation detection sensor according to claim 5, wherein the elastic modulus of the buffer material is less than 5 MPa.

7. The deformation detection sensor according to any one of claims 1 to 6, wherein the piezoelectric film overlaps the buffer material in a plan view.

8. A deformation detection sensor as described in any one of claims 1 to 7, further comprising: a first ground electrode arranged between the piezoelectric film and the retaining plate; and a signal electrode arranged between the piezoelectric film and the buffer material.

9. The deformation detection sensor according to claim 8, further comprising a second ground electrode disposed between the signal electrode and the buffer material, the signal electrode and the second ground electrode having elasticity, and the first ground electrode being softer than the signal electrode and the second ground electrode.

10. A deformation detection sensor as described in any of claims 1 to 7, further comprising: a signal electrode arranged between the piezoelectric film and the retaining plate; a first ground electrode arranged between the piezoelectric film and the buffer material; and a second ground electrode arranged between the signal electrode and the retaining plate, wherein the signal electrode and the second ground electrode are elastic, and the first ground electrode is softer than the signal electrode and the second ground electrode.

11. A deformation detection sensor according to any one of claims 1 to 10, wherein the orientation direction of the piezoelectric film forms an angle of 45 degrees with respect to a side of the piezoelectric film.

12. A deformation detection sensor as described in any one of claims 1 to 11, wherein the holding plate has a first main surface that is pressed by the user and a second main surface opposite the first main surface, and when the holding plate is pressed, the second main surface stretches at the pressed location, and the first main surface stretches at locations other than the pressed location.

13. An electronic device comprising the deformation detection sensor according to any one of claims 1 to 12, wherein the holding plate is any one of a touch panel, a liquid crystal display, an organic EL display, a liquid crystal display with a touch panel, and an organic EL display with a touch panel.

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