Sensors and electronic devices

Description

Technical Field

[0001] The present invention relates to a sensor for detecting deformation of a member and an electronic device including the sensor.

Background Art

[0002] Patent Document 1 describes a displacement sensor including an elastic body and a piezoelectric sheet. The elastic body is formed of a polymer having high strength. The piezoelectric sheet is attached to the elastic body. The displacement sensor is provided in a housing. The displacement sensor detects displacement of the housing. Specifically, the elastic body is attached to the housing. As the housing is deformed, the piezoelectric sheet attached to the elastic body is deformed. The piezoelectric sheet is polarized according to the amount of displacement of the piezoelectric sheet.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The direction of polarization of the piezoelectric sheet varies depending on the direction of deformation. Therefore, when the piezoelectric sheet is used as a sensor, polarization of different polarities may occur in the piezoelectric sheet depending on the deformation situation. In this case, since the level of the output signal of the sensor significantly changes depending on the position where the detection object is deformed, the stability as a sensor may decrease.

[0005] An object of the present invention is to provide a sensor that improves the stability of an output signal.

Means for Solving the Problems

[0006] A sensor according to an embodiment of the present invention includes a holding plate, A piezoelectric film is placed on the holding plate and has four sides and four corners, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, In a plan view, the reinforcing portion overlaps with the first and second corners of the four corners, which are located on the diagonal, but does not overlap with the third corner of the four corners, which is other than the first and second corners.

[0007] A sensor according to one embodiment of the present invention is Retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four vertices, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, In a plan view, the reinforcing portion is positioned near the first and second vertices, which are located on the diagonal of the four vertices, and does not overlap with the four vertices. [Effects of the Invention]

[0008] According to a sensor of one embodiment of the present invention, it is possible to provide a sensor that improves the stability of the output signal. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an exploded perspective view of the sensor 1 according to the first embodiment. [Figure 2] Figure 2 is a top view of sensor 1. [Figure 3] Figure 3 is an enlarged view of the piezoelectric film sensor 11 and the reinforcing parts 13 and 14. [Figure 4] Figure 4 is a side view of the piezoelectric film sensor 11. [Figure 5] Figures 5(A) and 5(B) show the deformation of the piezoelectric film sensor 11C1 according to Comparative Example 1. [Figure 6] Figure 6 shows the deformation of the piezoelectric film sensor 11. [Figure 7]Each of FIGS. 7(A), 7(B), and 7(C) is a diagram showing sensors 1a, 1b, and 1c according to Modification 1. [Figure 8] Each of FIGS. 8(A), 8(B), 8(C), 8(D), and 8(E) is a diagram showing sensors 1d, 1e, 1f, 1g, and 1h according to Modification 2. [Figure 9] FIG. 9 is a plan view of a sensor 1i according to Modification 3. [Figure 10] FIG. 10 is a diagram showing a sensor CP according to Comparative Example 2. [Figure 11] FIG. 11 is a diagram showing a sensor 1k according to Modification 4. [Figure 12] FIG. 12 is a diagram showing a sensor 1m according to Modification 5. [Figure 13] FIG. 13 is an exploded perspective view showing an electronic device EE1 including a sensor 1. [Figure 14] FIG. 14 is an exploded perspective view showing an electronic device EE2 according to a modification of the electronic device EE1. [Embodiments for Carrying Out the Invention]

[0010] [First Embodiment] Hereinafter, the sensor 1 according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of the sensor 1 according to the first embodiment. FIG. 2 is a top view of the sensor 1. FIG. 3 is an enlarged view of the piezoelectric film sensor 11 and the reinforcing portions 13 and 14. FIG. 4 is a side view of the piezoelectric film sensor 11.

[0011] In this embodiment, the directions are defined as shown in FIGS. 1 and 3. As shown in FIG. 1, the direction in which the holding plate 10 and the piezoelectric film sensor 11 are arranged in the order of the holding plate 10 and the piezoelectric film sensor 11 is the positive direction of the Z-axis. The opposite direction of the positive direction of the Z-axis is the negative direction of the Z-axis. As shown in FIG. 3, the direction in which the first corner portion D11 and the third corner portion D13 are arranged in the order of the first corner portion D11 and the third corner portion D13 is the positive direction of the X-axis. The opposite direction of the positive direction of the X-axis is the negative direction of the X-axis. The X-axis direction is orthogonal to the Z-axis direction. The direction in which the fourth corner portion D14 and the first corner portion D11 are arranged in the order of the fourth corner portion D14 and the first corner portion D11 is the positive direction of the Y-axis. The opposite direction of the positive direction of the Y-axis is the negative direction of the Y-axis. The Y-axis direction is orthogonal to the X-axis direction and the Z-axis direction. The direction from the first corner portion D11 to the second corner portion D12 is the first direction DIR1. The direction from the second corner portion D12 to the first corner portion D11 is the second direction DIR2. The direction from the third corner portion D13 to the fourth corner portion D14 is the third direction DIR3. The direction from the fourth corner portion D14 to the third corner portion D13 is the fourth direction DIR4.

[0012] Note that the X-axis direction, the Y-axis direction, and the Z-axis direction are directions defined for the purpose of explanation. Therefore, the X-axis direction, the Y-axis direction, and the Z-axis direction during actual use of the sensor 1 do not necessarily have to coincide with the X-axis direction, the Y-axis direction, and the Z-axis direction in each embodiment and each modification. Similarly, the first direction DIR1, the second direction DIR2, the third direction DIR3, and the fourth direction DIR4 during actual use of the sensor 1 do not necessarily have to coincide with the first direction DIR1, the second direction DIR2, the third direction DIR3, and the fourth direction DIR4 in each embodiment and each modification.

[0013] The sensor 1 is, for example, a module provided in an electronic device such as a smartphone. As shown in FIGS. 1 and 2, the sensor 1 includes a holding plate 10, a piezoelectric film sensor 11, an adhesive 12, and reinforcing portions 13 and 14.

[0014] As shown in Figures 1 and 2, the retaining plate 10 has a plate shape that includes a long side extending in the X-axis direction and a short side extending in the Y-axis direction. The retaining plate 10 includes a first main surface DF10 and a second main surface UF10. The first main surface DF10 and the second main surface UF10 are arranged in the positive Z-axis direction, in the order of the first main surface DF10 and the second main surface UF10. In plan view, the retaining plate 10 has a rectangular shape with four corners, including corner D1. For example, corner D1 is the end of the retaining plate 10 in the negative X-axis direction and the end in the negative Y-axis direction (see Figure 1). The retaining plate 10 is an elastic body that undergoes elastic deformation. The material of the retaining plate 10 is metal or resin, etc. For example, the outer edge of the retaining plate 10 and its vicinity are fixed to a frame-shaped housing or the like provided by electronic equipment.

[0015] As shown in Figures 1 to 3, the piezoelectric film sensor 11 has a plate shape including a long side extending in the X-axis direction and a short side extending in the Y-axis direction. The piezoelectric film sensor 11 has a first main surface SF1 and a second main surface SF2. The first main surface SF1 and the second main surface SF2 are arranged in the positive direction of the Z-axis, in the order of the first main surface SF1 and the second main surface SF2. The piezoelectric film sensor 11 is positioned on the holding plate 10. In Figures 1 and 2, the piezoelectric film sensor 11 is positioned at the corner D1 of the holding plate 10.

[0016] The piezoelectric film sensor 11 does not necessarily have to be fixed to corner D1 of the holding plate 10. The piezoelectric film sensor 11 may be fixed to a corner other than corner D1 among the four corners of the holding plate 10.

[0017] As shown in Figures 1 and 4, the piezoelectric film sensor 11 includes a piezoelectric film 110, a first electrode 111, a second electrode 112, and a detection circuit (not shown).

[0018] As shown in Figures 1 and 2, the piezoelectric film 110 has a sheet shape with a long side extending in the X-axis direction and a short side extending in the Y-axis direction. As shown in Figure 4, the piezoelectric film 110 has a first film main surface DF11 and a second film main surface UF11. The first film main surface DF11 and the second film main surface UF11 are arranged in the positive Z-axis direction, in the order of the first film main surface DF11 and the second film main surface UF11.

[0019] The piezoelectric film 110 is polarized according to the amount of deformation of the piezoelectric film 110. The direction of polarization when the piezoelectric film 110 is stretched in the first direction DIR1 or the second direction DIR2 is opposite to the direction of polarization when the piezoelectric film 110 is stretched in the third direction DIR3 or the fourth direction DIR4. For example, the piezoelectric film 110 is a film formed from a chiral polymer. A chiral polymer is, for example, polylactic acid (PLA), especially L-type polylactic acid (PLLA). PLLA, which is made of a chiral polymer, has a helical structure in its main chain. The piezoelectric film 110 has a piezoelectric constant of d14. As shown in Figures 2 and 3, the piezoelectric film 110 has piezoelectric properties when uniaxially stretched, with the molecules oriented in the orientation direction OD1. The orientation direction OD1 forms an angle of 0 degrees or 180 degrees with respect to the X-axis direction. For example, this 0 degrees includes angles including approximately 0 degrees ± 10 degrees, and this 180 degrees includes angles including approximately 180 degrees ± 10 degrees. The potential difference between the first film main surface DF11 and the second film main surface UF11 when polarized depends on the time derivative of the amount of deformation of the piezoelectric film 110 due to stretching or contraction. Note that the orientation direction OD1 does not necessarily form an angle of 0 degrees or 180 degrees with respect to the X axis. The orientation direction OD1 may form an angle of 90 degrees or 270 degrees with respect to the X axis.

[0020] As shown in Figure 3, the piezoelectric film 110 has a rectangular shape with four vertices K11, K12, K13, and K14, and four sides H1, H2, H3, and H4 connecting the four vertices K11, K12, K13, and K14. Vertex K11 is located at the negative end of the X-axis and the positive end of the Y-axis in the piezoelectric film 110. Vertex K12 is located diagonally from vertex K11. Vertex K13 is located at the positive end of the X-axis and the positive end of the Y-axis in the piezoelectric film 110. Vertex K14 is located diagonally from vertex K13. Side H1 connects vertex K11 and vertex K13. Side H2 connects vertex K12 and vertex K13. Side H3 connects vertex K12 and vertex K14. Edge H4 connects vertices K11 and K14.

[0021] As shown in Figures 2 and 3, the piezoelectric film 110 has four corners: a first corner D11, a second corner D12, a third corner D13, and a fourth corner D14.

[0022] In this embodiment, as shown in Figure 3, the first corner D11 is the end of the piezoelectric film 110 in the negative X direction and the end in the positive Y direction. The first corner D11 includes vertex K11 and the vicinity of vertex K11. The first corner D11 includes the position of the piezoelectric film 110 excluding vertex K11 (the vicinity of vertex K11). The first corner D11 does not include the midpoint M1 of side H1 and the midpoint M4 of side H4.

[0023] In this embodiment, the second corner D12 is located on the diagonal of the first corner D11. The second corner D12 includes vertex K12 and the vicinity of vertex K12. The second corner D12 includes the position in the piezoelectric film 110 excluding vertex K12 (the vicinity of vertex K12). The second corner D12 does not include the midpoint M2 of side H2 and the midpoint M3 of side H3.

[0024] In this embodiment, the third corner D13 is the end of the piezoelectric film 110 in the positive X direction and the end in the positive Y direction, as shown in Figure 3. The third corner D13 includes vertex K13 and the vicinity of vertex K13. The third corner D13 includes the position of the piezoelectric film 110 excluding vertex K13 (the vicinity of vertex K13). The third corner D13 does not include the midpoint M1 and the midpoint M2.

[0025] In this embodiment, the fourth corner D14 is located on the diagonal of the third corner D13. The fourth corner D14 includes vertex K14 and the vicinity of vertex K14. The fourth corner D14 includes the position in the piezoelectric film 110 excluding vertex K14 (the vicinity of vertex K14). The fourth corner D14 does not include the midpoint M3 and the midpoint M4.

[0026] The first electrode 111 is, for example, a signal electrode. As shown in Figure 4, the first electrode 111 is positioned on the first film main surface DF11. The first electrode 111 is fixed to the first film main surface DF11 by an adhesive (not shown) such as OCA (Optically Clear Adhesive). The first electrode 111 covers substantially the entire surface of the first film main surface DF11. The first electrode 111 is in contact with the holding plate 10 via the adhesive 12.

[0027] The second electrode 112 is, for example, a reference electrode. The second electrode 112 is connected to a reference potential (for example, ground potential). The second electrode 112 is positioned on the second film main surface UF11. The second electrode 112 is fixed to the second film main surface UF11 by an adhesive such as OCA (not shown). The second electrode 112 covers almost the entire surface of the second film main surface UF11. The second electrode 112, connected to the reference potential, prevents the signal generated by the piezoelectric film sensor 11 from affecting external equipment as noise.

[0028] Furthermore, the first electrode 111 does not necessarily have to be the signal electrode and the second electrode 112 the reference electrode. The first electrode 111 may be the reference electrode and the second electrode 112 may be the signal electrode.

[0029] The detection circuit converts the charge generated by the piezoelectric film 110 into a voltage signal. The detection circuit generates a digital signal by performing an A / D conversion on the voltage signal.

[0030] As shown in Figure 1, the adhesive 12 is placed between the holding plate 10 and the piezoelectric film sensor 11. The adhesive 12 is, for example, a double-sided adhesive tape. Of course, the adhesive 12 does not necessarily have to be double-sided tape.

[0031] The piezoelectric film sensor 11 is fixed to the second main surface UF10 of the holding plate 10 by the adhesive 12. As a result, the piezoelectric film sensor 11 outputs a signal corresponding to the deformation of the holding plate 10. Specifically, when the user pushes the holding plate 10 in the normal direction, the holding plate 10 bends and deforms. Along with the deformation of the holding plate 10, the piezoelectric film sensor 11 fixed to the holding plate 10 also bends and deforms. The piezoelectric film sensor 11 outputs a signal corresponding to the deformation of the piezoelectric film sensor 11.

[0032] The reinforcing portion 13 has a rectangular shape with four sides, as shown in Figures 1 to 3. The reinforcing portion 13 is positioned on the second main surface SF2. The reinforcing portion 13 is positioned at the first corner D11. As shown in Figures 1 to 3, the reinforcing portion 13 overlaps the piezoelectric film sensor 11 in a plan view. The reinforcing portion 13 overlaps the first corner D11 in a plan view. The reinforcing portion 13 may be formed of a material having an elastic modulus higher than that of the retaining plate 10, or it may be formed of a material having an elastic modulus lower than that of the retaining plate 10. The reinforcing portion 13 suppresses deformation of the piezoelectric film 110. The reinforcing portion 13 suppresses deformation of the first corner D11. Specifically, the first corner D11 becomes less prone to deformation (harder) than the parts of the piezoelectric film 110 where the reinforcing portions 13 and 14 are not provided, due to the presence of the reinforcing portion 13. Therefore, even when a force is applied to the piezoelectric film sensor 11 in the direction normal to the film sensor (for example, when a user presses the holding plate 10), the first corner portion D11 is less likely to twist in the first direction DIR1 or the second direction DIR2 due to that force.

[0033] The reinforcing portion 14 is positioned at the second corner D12, as shown in Figures 1 to 3. In a plan view, the reinforcing portion 14 overlaps the second corner D12. The reinforcing portion 14 suppresses deformation of the second corner D12. The other components of the reinforcing portion 14 are the same as those of the reinforcing portion 13, so their description is omitted.

[0034] In this embodiment, the reinforcing parts 13 and 14 are not located at the third corner D13 and the fourth corner D14. When viewed from above, the reinforcing parts 13 and 14 do not overlap the third corner D13 and the fourth corner D14.

[0035] The reinforcing parts 13 and 14 may be frame-shaped housings found in electronic devices such as smartphones. For example, the housing can fix side H4 and its vicinity, and side H3 and its vicinity, of the piezoelectric film sensor 11 to the holding plate 10. The housing can suppress deformation of the first corner D11, the second corner D12, and the fourth corner D14.

[0036] (effect) The effects of sensor 1 will be explained below in comparison with the sensor in the comparative example (hereinafter simply referred to as Comparative Example 1). Figures 5(A) and 5(B) show the deformation of the piezoelectric film sensor 11C1 in Comparative Example 1, respectively. Figure 6 shows the deformation of the piezoelectric film sensor 11. In the experiment shown in Figure 6, the reinforcing portion overlaps the first corner D11, the second corner D12, and the fourth corner D14. In the experiment shown in Figure 6, the piezoelectric film sensor 11 is positioned at the corner D1 of the holding plate 10, but it does not overlap with the frame-shaped housing or the like provided by the electronic device.

[0037] The piezoelectric film sensor 11C1 of Comparative Example 1 differs from the piezoelectric film sensor 11 of this embodiment in that the reinforcing portions 13 and 14 do not overlap the first corner portion D11 and the second corner portion D12. Therefore, the piezoelectric film 110 of the piezoelectric film sensor 11C1 of Comparative Example 1 is not deformed by the reinforcing portions 13 and 14. Figure 5(A) shows the deformation of the piezoelectric film sensor 11C1 when the third corner portion D13 is pressed in the normal direction. When the piezoelectric film 110 of the piezoelectric film sensor 11C1 is pressed in the normal direction at the third corner portion D13, it stretches along the fourth direction DIR4 and contracts along the first direction DIR1 and the second direction DIR2, so the portion that is positively polarized with respect to the reference potential becomes dominant. Figure 5(B) shows the deformation of the piezoelectric film sensor 11C1 when the second corner portion D12 is pressed in the normal direction. When the second corner D12 of the piezoelectric film sensor 11C1 is pressed in the normal direction, the piezoelectric film 110 stretches along the first direction DIR1 and contracts along the third direction DIR3 and the fourth direction DIR4, so that the portion that is negatively polarized with respect to the reference potential is predominant.

[0038] The output of the piezoelectric film sensor 11C1 corresponds to the total charge generated on the piezoelectric film 110. Therefore, in the piezoelectric film sensor 11C1 of Comparative Example 1, the polarity of the sensor output is reversed when the second corner D12 is pressed in the normal direction compared to when the fourth corner D14 is pressed in the normal direction.

[0039] Furthermore, in Comparative Example 1, if any of the midpoints of the four sides (midpoints M1 to M4) are pressed, the area of ​​the part that is positively polarized with respect to the reference potential and the area of ​​the part that is negatively polarized with respect to the reference potential will be the same. Therefore, in the piezoelectric film sensor 11C1 of Comparative Example 1, if any of the midpoints of the four sides (midpoints M1 to M4) are pressed, the output of the sensor will become extremely small or even "0".

[0040] In the sensor 1 according to this embodiment, since the reinforcing parts 13 and 14 do not overlap the third corner D13, when the third corner D13 is pressed in the normal direction, the piezoelectric film 110 stretches along the fourth direction DIR4. On the other hand, the deformation of the first corner D11 and the second corner D12 is suppressed by the reinforcing parts 13 and 14. Therefore, the piezoelectric film 110 is less likely to contract or stretch along the first direction DIR1 or the second direction DIR2. Thus, the portion of the piezoelectric film 110 that is positively polarized with respect to the reference potential is predominant. Accordingly, in the sensor 1 according to this embodiment, the output of the piezoelectric film sensor 11 when the third corner D13 is pressed in the normal direction is similar to the output of the piezoelectric film sensor 11C1 of Comparative Example 1 shown in Figure 5(A).

[0041] Figure 6 shows the deformation of the piezoelectric film sensor 11 when the second corner D12 is pressed in the normal direction. The deformation of the first corner D11 and the second corner D12 is suppressed by the reinforcing parts 13 and 14. Therefore, the piezoelectric film 110 is difficult to shrink or stretch along the first direction DIR1 and the second direction DIR2. On the other hand, the force applied to the second corner D12 in the normal direction is transmitted to the holding plate 10, causing the piezoelectric film 110 to stretch along the fourth direction DIR4. Consequently, the portion of the piezoelectric film 110 that is positively polarized with respect to the reference potential is dominant. Therefore, in the piezoelectric film sensor 11 of this embodiment, the polarity of the sensor output does not reverse when the second corner D12 is pressed in the normal direction compared to when the fourth corner D14 is pressed in the normal direction.

[0042] Furthermore, in the piezoelectric film sensor 11 of this embodiment, even if any of the midpoints of the four sides (midpoints M1 to M4) are pressed, the portion that is positively polarized with respect to the reference potential becomes dominant. Therefore, in the piezoelectric film sensor 11 of this embodiment, if any of the midpoints of the four sides (midpoints M1 to M4) are pressed, the output of the sensor will not become extremely small or become "0".

[0043] Therefore, sensor 1 can prevent the output of signals with unintended polarities, either positive or negative. Furthermore, sensor 1 can prevent a significant decrease in the output signal value. Consequently, sensor 1 can improve the stability of the output signal of the piezoelectric film sensor 11.

[0044] Furthermore, the calculation circuit (not shown) connected to sensor 1 determines that a user has pressed the sensor when the value of the output signal of the piezoelectric film sensor 11 exceeds a predetermined threshold. The calculation circuit (not shown) determines that the user has released the pressing operation when the value of the output signal of the piezoelectric film sensor 11 falls below a predetermined threshold (a predetermined negative value). In this embodiment, sensor 1 does not reverse the polarity of the output signal, nor does the value of the output signal decrease significantly, thus preventing misjudgment by the calculation circuit.

[0045] Furthermore, even if the orientation direction OD1 of the piezoelectric film 110 in sensor 1 forms an angle of 0 degrees or 180 degrees with respect to the X-axis direction, the polarity of the output of sensor 1 does not reverse when the second corner D12 is pressed in the normal direction compared to when the fourth corner D14 is pressed in the normal direction. Therefore, the effect is achieved that the output of the piezoelectric film sensor 11 as a sensor becomes extremely small or never becomes "0".

[0046] [Example 1] The following describes sensors 1a, 1b, and 1c related to Modification 1 of Sensor 1 with reference to the drawings. Figures 7(A), 7(B), and 7(C) are diagrams showing sensors 1a, 1b, and 1c related to Modification 1.

[0047] As shown in Figure 7(A), sensor 1a differs from sensor 1 in that it has reinforcing parts 13a and 14a that are different from reinforcing parts 13 and 14. Specifically, the shape of reinforcing parts 13a and 14a is L-shaped when viewed from above. The other components of sensor 1a are the same as those of sensor 1, so their description is omitted.

[0048] As shown in Figure 7(B), sensor 1b differs from sensor 1 in that it has reinforcing parts 13b and 14b, which are different from reinforcing parts 13 and 14. Specifically, the shapes of reinforcing parts 13b and 14b are triangular when viewed from above. The other components of sensor 1b are the same as those of sensor 1, so their description is omitted.

[0049] As shown in Figure 7(C), sensor 1c differs from sensor 1 in that it has one reinforcing portion 13c. The reinforcing portion 13c has a rectangular shape extending from the first corner D11 to the second corner D12. The other components of sensor 1c are the same as those of sensor 1, so their description is omitted.

[0050] Sensors 1a, 1b, and 1c each produce the same effect as sensor 1.

[0051] [Differentiation 2] The following describes sensors 1d, 1e, 1f, 1g, and 1h related to modified example 2 of sensor 1, with reference to the drawings. Figures 8(A), 8(B), 8(C), 8(D), and 8(E) are diagrams showing sensors 1d, 1e, 1f, 1g, and 1h related to modified example 2.

[0052] Sensors 1d, 1e, 1f, 1g, and 1h differ from sensor 1 in that, when viewed from above, their reinforcing portion overlaps with the fourth corner D14.

[0053] As shown in Figure 8(A), the sensor 1d further includes a reinforcing portion 15. The reinforcing portion 15 is located at the fourth corner D14. In a plan view, the reinforcing portion 15 overlaps with the fourth corner D14. The other components of the reinforcing portion 15 are the same as those of the reinforcing portion 13, so their description is omitted.

[0054] As shown in Figure 8(B), the sensor 1e has a reinforcing portion 13e that overlaps with the first corner D11, the second corner D12, and the fourth corner D14 when viewed from above. The reinforcing portion 13e has an L-shape when viewed from above. Part of the reinforcing portion 13e extends from the first corner D11 toward the fourth corner D14. Therefore, the reinforcing portion 13e is positioned in the area connecting the fourth corner D14 toward the first corner D11. The remaining part of the reinforcing portion 13e extends from the fourth corner D14 toward the second corner D12. Therefore, the reinforcing portion 13e is positioned in the area connecting the fourth corner D14 toward the second corner D12. The other configurations of the reinforcing portion 13e are the same as those of the reinforcing portion 13, so their description is omitted.

[0055] As shown in Figure 8(C), the sensor 1f has a reinforcing portion 13f that is different from the reinforcing portion 13e. A portion of the reinforcing portion 13f extends from the first corner D11 toward the second corner D12. The other components of the reinforcing portion 13f are the same as those of the reinforcing portion 13e, so their description is omitted.

[0056] As shown in Figure 8(D), the sensor 1g is equipped with one reinforcing section 13g. The reinforcing section 13g is triangular in shape when viewed from above. The three vertices of the reinforcing section 13g are located at the first corner D11, the second corner D12, and the fourth corner D14, respectively. The other components of the reinforcing section 13g are the same as those of the reinforcing section 13, so their description is omitted.

[0057] As shown in Figure 8(E), the sensor 1h is equipped with one reinforcing portion 13h. The reinforcing portion 13h does not cover vertex K13 or the area around vertex K13. The reinforcing portion 13h covers all parts of the piezoelectric film sensor 11 except for vertex K13 and the area around vertex K13. The other configurations of the reinforcing portion 13h are the same as those of the reinforcing portion 13, so their description is omitted.

[0058] Each of sensors 1a to 1h produces the same effect as sensor 1.

[0059] [Difference 3] The following describes the sensor 1i according to the modified example 3 of sensor 1, with reference to the drawings. Figure 9 is a plan view of the sensor 1i according to the modified example 3.

[0060] As shown in Figure 9, sensor 1i differs from sensor 1 in that it has reinforcing parts 13i, 14i, 15i, and 16i that are different from reinforcing parts 13 and 14. Each of the reinforcing parts 13i, 14i, 15i, and 16i is not located at vertices K11 to K14 in the piezoelectric film sensor 11. In other words, each of the reinforcing parts 13i, 14i, 15i, and 16i does not overlap with vertices K11 to K14 when viewed from above. Vertex K11 corresponds to the first vertex in this application. Vertex K12 corresponds to the second vertex in this application. Vertex K13 corresponds to the third vertex in this application. Vertex K14 corresponds to the fourth vertex in this application.

[0061] Reinforcement portion 13i is located near vertex K11 when viewed from above. Reinforcement portion 13i is located between vertex K11 and midpoint M1. Reinforcement portion 13i does not overlap with vertex K11 and midpoint M1 when viewed from above. Reinforcement portion 14i is located near vertex K11 when viewed from above. Reinforcement portion 14i is located between vertex K11 and midpoint M4. Reinforcement portion 14i does not overlap with vertex K11 and midpoint M4 when viewed from above. The deformation of the first corner portion D11 is suppressed by reinforcement portions 13i and 14i.

[0062] Reinforcement section 15i is located near vertex K12 when viewed from above. Reinforcement section 15i is located between vertex K12 and midpoint M2. Reinforcement section 15i does not overlap with vertex K12 or midpoint M2 when viewed from above. Reinforcement section 16i is located near vertex K12 when viewed from above. Reinforcement section 16i is located between vertex K12 and midpoint M3. Reinforcement section 16i does not overlap with vertex K12 or midpoint M3 when viewed from above. The deformation of the second corner section D12 is suppressed by reinforcement sections 15i and 16i.

[0063] Each of the reinforcing sections 13i to 16i does not suppress the deformation of the third corner D13 and the fourth corner D14.

[0064] (effect) Sensor 1i exhibits the same effects as sensor 1. These effects will be explained below with reference to the drawings. Figure 10 shows sensor CP according to comparative example 2. As shown in Figure 10, sensor CP is equipped with four reinforcing parts CP13, CP14, CP15, and CP16. The reinforcing parts CP13, CP14, CP15, and CP16 are not located at the corners of the piezoelectric film of the piezoelectric film sensor CP11 in sensor CP. When viewed from above, each of the reinforcing parts CP13, CP14, CP15, and CP16 overlaps with the midpoints CPM1, CPM4, CPM2, and CPM3, respectively.

[0065] In sensor CP, the reinforcing parts CP13, CP14, CP15, and CP16 do not overlap with any of the four corners of the piezoelectric film. Therefore, when the third corner DP13 or the fourth corner DP14 of sensor CP is pressed in the normal direction, the piezoelectric film stretches along the third direction DIR3 and the fourth direction DIR4, and contracts along the first direction DIR1 and the second direction DIR2, resulting in a dominant portion that is positively polarized with respect to the reference potential. On the other hand, when the first corner DP11 or the second corner DP12 of sensor CP is pressed in the normal direction, the piezoelectric film stretches along the first direction DIR1 and the second direction DIR2, and contracts along the third direction DIR3 and the fourth direction DIR4, resulting in a dominant portion that is negatively polarized with respect to the reference potential.

[0066] The output of the piezoelectric film sensor in sensor CP corresponds to the total charge generated on the piezoelectric film. Therefore, in the piezoelectric film sensor of Comparative Example 2, for example, the polarity of the sensor output will be reversed when the second corner D12 is pressed in the normal direction compared to when the fourth corner D14 is pressed in the normal direction.

[0067] On the other hand, in sensor 1i, the reinforcing parts 13i and 14i are located near vertex K11, and the reinforcing parts 15i and 16i are located near vertex K12. Therefore, the piezoelectric film 110 is less likely to stretch along the first direction DIR1 and the second direction DIR2 compared to sensor CP. For this reason, in the piezoelectric film of sensor 1i, for the same reasons as in sensor 1, the polarity of the sensor output is not determined when the second corner D12 is pressed in the normal direction or when the fourth corner D14 is pressed in the normal direction. Also, in the piezoelectric film sensor 11 of sensor 1i, when any of the midpoints of the four sides (midpoints M1 to M4) is pressed, the sensor output will not become extremely small or become "0". Therefore, sensor 1i can prevent the output of a signal with an unintended polarity, either positive or negative, similar to sensor 1. Furthermore, sensor 1i can prevent a significant decrease in the value of the output signal. Consequently, sensor 1i can improve the stability of the output signal of the piezoelectric film sensor 11.

[0068] [Differentiation Example 4] Below, we will describe the sensor 1k according to the modified version 4 of sensor 1 with reference to the drawings. Figure 11 is a diagram showing the sensor 1k according to the modified version 4.

[0069] As shown in Figure 11, sensor 1k differs from sensor 1 in that the reinforcing parts 13 and 14 do not overlap with the piezoelectric film sensor 11 in a plan view. The reinforcing parts 13 and 14 are arranged, for example, on the holding plate 10. Reinforcing part 13 is located near the first corner D11. In sensor 1k, the reinforcing part 13 is located next to the first corner D11. The reinforcing part 13 is located on the positive side of the Y-axis from the piezoelectric film sensor 11. The reinforcing part 13 is not in contact with the piezoelectric film sensor 11. Reinforcing part 14 is located near the second corner D12. The reinforcing part 14 is located next to the second corner D12. The reinforcing part 14 is located on the positive side of the X-axis from the piezoelectric film sensor 11.

[0070] Since the reinforcing part 13 is positioned near the first corner D11, the first corner D11 is fixed to the retaining plate 10. Since the reinforcing part 14 is positioned near the second corner D12, the second corner D12 is fixed to the retaining plate 10. For this reason, in the piezoelectric film sensor 11 of sensor 1k, the polarity of the sensor output does not reverse when the second corner D12 is pressed in the normal direction and when the fourth corner D14 is pressed in the normal direction, just as in sensor 1. Also, in the piezoelectric film sensor 11 of sensor 1k, when any of the midpoints of the four sides (midpoints M1 to M4) is pressed, the sensor output will not become extremely small or become "0". Therefore, for the same reasons as sensor 1, sensor 1k can improve the stability of the output signal of the piezoelectric film sensor 11.

[0071] [Difference 5] The following describes sensor 1m according to modified example 5 of sensor 1, with reference to the drawings. Figure 12 shows sensor 1m according to modified example 5.

[0072] As shown in Figure 12, sensor 1m differs from sensor 1 in that multiple sets of piezoelectric film sensors and reinforcing parts are arranged on the holding plate 10. In Figure 12, two sets of piezoelectric film sensors and reinforcing parts are arranged on the holding plate 10. Specifically, sensor 1m differs from sensor 1 in that it further comprises a piezoelectric film sensor 20 and reinforcing parts 23 and 24. The piezoelectric film sensor 20 is located at corner D2 of the holding plate 10. Corner D2 is located diagonally to corner D1 of the holding plate 10. The reinforcing part 23 is located at the first corner of the piezoelectric film sensor 20. The reinforcing part 24 is located at the second corner of the piezoelectric film sensor 20. The other configurations of the piezoelectric film sensor 20 are the same as those of the piezoelectric film sensor 11, so their explanation is omitted.

[0073] The piezoelectric film sensor 20 may be positioned at corners other than corners D1 and D2 of the holding plate 10.

[0074] Furthermore, the sensor 1m may be equipped with three or more sets of piezoelectric film sensors and reinforcing parts.

[0075] [Electronic equipment EE1] The electronic device EE1 equipped with sensor 1 will be described below with reference to the drawings. Figure 13 is an exploded perspective view showing the electronic device EE1 equipped with sensor 1.

[0076] As shown in Figure 13, the electronic device EE1 includes a sensor 1 and a touch panel 30. For example, the touch panel 30 is located between the retaining plate 10 and the piezoelectric film sensor 11. The size of the touch panel 30 is approximately the same as the size of the retaining plate 10. In the electronic device EE1, the piezoelectric film sensor 11 is located at the corner of the touch panel 30. The touch panel 30 is a touch panel of the resistive or capacitive type. Such an electronic device EE1 is a smartphone, etc.

[0077] [Differential model of electronic device EE1] The following describes electronic device EE2, a modified version of electronic device EE1, with reference to the drawings. Figure 14 is an exploded perspective view showing electronic device EE2, a modified version of electronic device EE1.

[0078] As shown in Figure 14, electronic device EE2 differs from electronic device EE1 in that it further includes a display panel 40. The display panel 40 is, for example, located between the touch panel 30 and the piezoelectric film sensor 11. The size of the display panel 40 is approximately the same as the size of the retaining plate 10. In electronic device EE2, the piezoelectric film sensor 11 is located at the corner of the display panel 40. The display panel 40 is an organic EL display or a liquid crystal display, etc. Such electronic device EE2 is a smartphone, etc.

[0079] The display panel 40 does not necessarily have to be located between the touch panel 30 and the piezoelectric film sensor 11. For example, the display panel 40 may be located between the touch panel 30 and the retaining plate 10.

[0080] [Other embodiments] The description of this embodiment should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, rather than by the embodiments described above. Furthermore, the scope of the present invention includes the scope equivalent to the claims.

[0081] Furthermore, the sensors according to the present invention are not limited to sensors 1, 1a to 1m, but can be modified within the scope of the gist thereof. The configurations of sensors 1, 1a to 1m may be combined in any way.

[0082] In this invention, the first and second corners only need to be arranged diagonally. Therefore, the combination of the first and second corners does not necessarily have to be the combination of two corners shown in Figures 1 to 14. For example, in sensor 1, the second corner D12 may correspond to the first corner in this invention, and the fourth corner D14 may correspond to the second corner in this invention.

[0083] The present invention has the following structure.

[0084] (1) Retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four corners, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, In a plan view, the reinforcing portion overlaps with the first and second corners of the four corners, which are located on the diagonal, but does not overlap with the third corner of the four corners other than the first and second corners. Sensor.

[0085] (2) Retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four vertices, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, The reinforcing portion is positioned in the vicinity of the first and second vertices, which are located on the diagonal of the four vertices, in a plan view, and does not overlap with the four vertices. Sensor.

[0086] (3) The reinforcing portion overlaps the fourth corner which is located on the diagonal of the third corner, (1) The sensor described above.

[0087] (4) The reinforcing portion is positioned in a location that overlaps with the portion of the piezoelectric film connecting the fourth corner to the first corner, and the portion connecting the fourth corner to the second corner. (3) The sensor described above.

[0088] (5) The reinforcing portion is positioned so as not to overlap with the vicinity of the third vertex, which is one of the four vertices other than the first and second vertices, but to overlap with the vicinity of the fourth vertex, which is located on the diagonal of the third vertex. (2) The sensor described above.

[0089] (6) The reinforcing portion, when viewed from above, does not overlap the piezoelectric film. The sensor described in (2) or (5).

[0090] (7) The piezoelectric film is positioned at the corner of the holding plate. A sensor as described in any of (1) to (6).

[0091] (8) Multiple sets of the piezoelectric film and the reinforcing portion are arranged on the holding plate. A sensor as described in any of (1) through (7).

[0092] (9) The piezoelectric film sensor further includes the piezoelectric film, a first electrode and a second electrode, The piezoelectric film has a first main film surface and a second main film surface, The first electrode is positioned on the main surface of the first film and is in contact with the holding plate. The second electrode is positioned on the main surface of the second film and is connected to a reference potential. A sensor as described in any of (1) through (8).

[0093] (10) A sensor as described in any of (1) to (9), Touch panel and It is equipped with electronic equipment.

[0094] (11) It also has a display panel. (10) Electronic equipment as described above. [Explanation of Symbols]

[0095] 1,1a~1m,CP: Sensor 10: Holding plate 11,11C1,CP11,20: Piezoelectric film sensor 110: Piezoelectric film 111: 1st electrode 112:Second electrode 12: Adhesive 13, 13a~13i, 14, 14a, 14b, 14i, 15, 15i, 16i, 23, 24, CP13~CP16: Reinforcement section 30: Touch panel 40: Display panel D1, D2: Corner D11,DP11: 1st corner D12, DP12: Second corner D13, DP13: Third corner D14, DP14: Fourth corner H1~H4: Sides M1~M4, CPM1~CPM4: Midpoint K11~K14: Vertex EE1,EE2:Electronic equipment DF10, SF1: 1st main surface UF10, SF2: Second main surface DF11: Main surface of the first film UF11: Second film main surface DIR1: 1st direction DIR2:Second direction DIR3: Third direction DIR4: Fourth direction OD1: Orientation direction

Claims

1. Retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four corners, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, In a plan view, the reinforcing portion overlaps with the first and second corners of the four corners, which are located on the diagonal, but does not overlap with the third corner of the four corners other than the first and second corners. Sensor.

2. Retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four vertices, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, The reinforcing portion, in a plan view, overlaps with the piezoelectric film and is positioned near the first and second vertices which are located on the diagonal of the four vertices, and does not overlap with the four vertices. Sensor.

3. The reinforcing portion overlaps the fourth corner which is located on the diagonal of the third corner, The sensor according to claim 1.

4. The reinforcing portion is positioned in a location that overlaps with the portion of the piezoelectric film connecting the fourth corner to the first corner, and the portion connecting the fourth corner to the second corner. The sensor according to claim 3.

5. The reinforcing portion is positioned so as not to overlap with the vicinity of the third vertex, which is one of the four vertices other than the first and second vertices, but to overlap with the vicinity of the fourth vertex, which is located on the diagonal of the third vertex. The sensor according to claim 2.

6. A retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four vertices, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, The aforementioned reinforcing portion is In a plan view, it is located near the first and second vertices which are positioned on the diagonal of the four vertices, and does not overlap with the four vertices. In a plan view, the fourth vertex is positioned so as to not overlap with the vicinity of the third vertex other than the first and second vertices among the four vertices, but rather overlapping with the vicinity of the fourth vertex which is located on the diagonal of the third vertex. Sensor.

7. The reinforcing portion, when viewed from above, does not overlap the piezoelectric film. The sensor according to claim 6.

8. The piezoelectric film is positioned at the corner of the holding plate. The sensor according to any one of claims 1 to 7.

9. Multiple sets of the piezoelectric film and the reinforcing portion are arranged on the holding plate. The sensor according to any one of claims 1 to 7.

10. A retaining plate and A piezoelectric film is placed on the holding plate and has four sides and four vertices, A reinforcing portion that suppresses deformation of the piezoelectric film, It is equipped with, The reinforcing portion is positioned in the vicinity of the first and second vertices, which are located on the diagonal of the four vertices, in a plan view, and does not overlap with the four vertices. Multiple sets of the piezoelectric film and the reinforcing portion are arranged on the holding plate. Sensor.

11. The piezoelectric film sensor further includes the piezoelectric film, a first electrode and a second electrode, The piezoelectric film has a first main film surface and a second main film surface, The first electrode is positioned on the main surface of the first film and is in contact with the holding plate. The second electrode is positioned on the main surface of the second film and connected to a reference potential. The sensor according to any one of claims 1 to 7 and claim 10.

12. A sensor according to any one of claims 1 to 7 and claim 10, Touch panel and It is equipped with electronic equipment.

13. It also has a display panel. The electronic device according to claim 12.

Images