Electronic equipment

Abstract

To provide an electronic apparatus capable of increasing detection sensitivity of a piezoelectric sensor.SOLUTION: An electronic apparatus includes: an operation board that has an upper main surface and a lower main surface, and allows a part of a user's body or an operation member to abut on the upper main surface of the operation board; a piezoelectric sensor that is provided on the lower main surface of the operation board and outputs a detection signal for detecting deformation of the operation board; an opposing member that has an opposing surface facing the lower main surface of the operation board; and a support member that abuts on the lower main surface of the operation board and the opposing surface of the opposing member. The support member is separated from an outer edge of the piezoelectric sensor by at least 10 mm when viewed in a vertical direction, and the support member applies force in an upper direction of magnitude of 2 N or smaller to the operation board.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electronic device equipped with a piezoelectric sensor. [Background technology]

[0002] As an example of an invention related to a conventional electronic device, a distribution sensor described in Patent Document 1 is known. This distribution sensor includes a portion corresponding to a piezoelectric element, a base substrate, and a supporting spacer. The base substrate has, for example, a rectangular shape. The supporting spacers are disposed at the four corners of the base substrate. The portion corresponding to the piezoelectric element is disposed on the base substrate. The portion corresponding to the piezoelectric element is supported by the supporting spacers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-337979 A Summary of the Invention [Problem to be solved by the invention]

[0004] In electronic devices equipped with piezoelectric sensors, there is a demand for improving the detection sensitivity of the piezoelectric sensors. However, in the distributed sensor described in Patent Document 1, the support spacer may hinder the deformation of the piezoelectric element. Therefore, it may be difficult to improve the detection sensitivity of the distributed sensor.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an electronic device capable of improving the detection sensitivity of a piezoelectric sensor. [Means for solving the problem]

[0006] An electronic device according to one embodiment of the present invention includes: An operation plate having an upper main surface and a lower main surface, wherein a part of a user's body or an operation member comes into contact with the upper main surface of the operation plate; a piezoelectric sensor provided on the lower main surface of the operation plate, the piezoelectric sensor detecting deformation of the operation plate and outputting a detection signal; an opposing member having an opposing surface facing the lower main surface of the operation plate; a support member in contact with the lower main surface of the operation plate and the opposing surface of the opposing member; Equipped with the support member is spaced from an outer edge of the piezoelectric sensor by 10 mm or more when viewed in the up-down direction, The support member applies an upward force of 2N or less to the operation plate.

[0007] In this specification, an axis or member extending in the front-rear direction does not necessarily refer only to an axis or member that is parallel to the front-rear direction. An axis or member extending in the front-rear direction refers to an axis or member that is inclined within a range of ±45° with respect to the front-rear direction. Similarly, an axis or member extending in the up-down direction refers to an axis or member that is inclined within a range of ±45° with respect to the up-down direction. An axis or member extending in the left-right direction refers to an axis or member that is inclined within a range of ±45° with respect to the left-right direction.

[0008] In the following, the first member, the second member, and the third member are structures that an electronic device has. In this specification, the term "the first member is supported by the second member" includes both the case where the first member is attached to the second member (i.e., fixed or held) so as to be immovable relative to the second member, and the case where the first member is attached to the second member so as to be movable relative to the second member. In addition, the term "the first member is supported by the second member" includes both the case where the first member is directly attached to the second member, and the case where the first member is attached to the second member via the third member.

[0009] In this specification, the first member and the second member aligned in the front-rear direction refer to the following state. When the first member and the second member are viewed in a direction perpendicular to the front-rear direction, both the first member and the second member are arranged on an arbitrary straight line indicating the front-rear direction. In this specification, the first member and the second member aligned in the front-rear direction when viewed in the up-down direction refer to the following state. When the first member and the second member are viewed in the up-down direction, both the first member and the second member are arranged on an arbitrary straight line indicating the front-rear direction. In this case, when the first member and the second member are viewed from a left-right direction different from the up-down direction, either one of the first member and the second member may not be arranged on an arbitrary straight line indicating the front-rear direction. Note that the first member and the second member may be in contact with each other. The first member and the second member may be separated from each other. A third member may be present between the first member and the second member. This definition is also applied to directions other than the front-rear direction.

[0010] In this specification, the first member being disposed in front of the second member refers to the following state. A part of the first member is disposed within an area through which the second member passes when it translates forward. Thus, the first member may be contained within an area through which the second member passes when it translates forward, or may protrude from an area through which the second member passes when it translates forward. In this case, the first member and the second member are aligned in the front-rear direction. This definition also applies to directions other than the front-rear direction.

[0011] In this specification, a first member being disposed in front of a second member when viewed in the left-right direction refers to the following state: when viewed in the left-right direction, the first member and the second member are aligned in the front-to-rear direction, and when viewed in the left-to-right direction, a portion of the first member that faces the second member is disposed in front of the second member. In this definition, the first member and the second member do not have to be aligned in the front-to-rear direction in three dimensions. This definition also applies to directions other than the front-to-rear direction.

[0012] In this specification, the term "the first member is disposed in front of the second member" refers to the following state: the first member is disposed in front of a plane that passes through the front end of the second member and is perpendicular to the front-rear direction. In this case, the first member and the second member may or may not be aligned in the front-rear direction. This definition also applies to directions other than the front-rear direction.

[0013] In this specification, unless otherwise specified, each part of the first member is defined as follows. The front part of the first member means the front half of the first member. The rear part of the first member means the rear half of the first member. The left part of the first member means the left half of the first member. The right part of the first member means the right half of the first member. The upper part of the first member means the upper half of the first member. The lower part of the first member means the lower half of the first member. The front end of the first member means the front end of the first member. The rear end of the first member means the rear end of the first member. The left end of the first member means the left end of the first member. The right end of the first member means the right end of the first member. The upper end of the first member means the upper end of the first member. The lower end of the first member means the lower end of the first member. The front end of the first member means the front end of the first member and its vicinity. The rear end of the first member means the rear end of the first member and its vicinity. The left end of the first member means the left end of the first member and its vicinity. The right end of the first member means the right end of the first member and its vicinity. The upper end of the first member means the upper end of the first member and its vicinity. The lower end of the first member means the lower end of the first member and its vicinity.

[0014] In this specification, the term "the first member and the second member are electrically connected" includes the following two meanings. The first meaning is that the first member and the second member are physically in contact with each other, so that a direct current can flow between the first member and the second member. The second meaning is that the first member and the third member are physically in contact with each other, and the third member and the second member are physically in contact with each other, so that a direct current can flow between the first member and the second member. In the second meaning, the first member and the second member may or may not be in physical contact with each other. In the second meaning, the third member may be a single member or may include multiple members. Effect of the Invention

[0015] According to the electronic device of the present invention, the detection sensitivity of the piezoelectric sensor can be improved. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a top view of the electronic device 1. As shown in FIG. [Diagram 2] FIG. 2 is a cross-sectional view of the electronic device 1 taken along line AA. [Diagram 3] FIG. 3 is a cross-sectional view of the electronic device 1 taken along line BB. [Figure 4] FIG. 4 is a bottom view of the piezoelectric sensor 13 and a cross-sectional view taken along CC. [Diagram 5] FIG. 5 is a cross-sectional view of the experimental setup 100. [Figure 6] FIG. 6 is a top view of the experimental apparatus 100. [Figure 7] FIG. 7 is a graph showing the results of Experiment 1. [Figure 8] FIG. 8 is a top view of the experimental apparatus 100. [Figure 9] FIG. 9 is a graph showing the results of Experiment 2. [Figure 10] FIG. 10 is a top view of the experimental setup 100. [Figure 11] FIG. 11 is a graph showing the results of Experiment 3. [Figure 12] FIG. 12 is a top view of the experimental apparatus 100. [Figure 13] FIG. 13 is a graph showing the results of Experiment 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] (Embodiment) The configuration of an electronic device 1 according to an embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a top view of the electronic device 1. Fig. 2 is a cross-sectional view of the electronic device 1 taken along line AA. Fig. 3 is a cross-sectional view of the electronic device 1 taken along line BB. Fig. 4 is a bottom view of the piezoelectric sensor 13 and a cross-sectional view taken along line CC.

[0018] In addition, in this specification, directions are defined as follows. In the electronic device 1, the direction in which the normal vector of the upper main surface S11 of the operation plate 2 extends is defined as the upward direction. The direction in which the normal vector of the lower main surface S12 of the operation plate 2 extends is defined as the downward direction. The direction in which the long side of the operation plate 2 extends is defined as the front-rear direction. The direction in which the short side of the operation plate 2 extends is defined as the left-right direction. The up-down direction, the left-right direction, and the front-rear direction are mutually perpendicular. Note that the definitions of directions in this specification are merely examples. Therefore, the directions in the actual use of the electronic device 1 do not need to match the directions in this specification. Also, the up-down direction may be reversed in FIG. 1. Similarly, the left-right direction may be reversed in FIG. 1. The front-rear direction may be reversed in FIG. 1.

[0019] The electronic device 1 is a portable electronic terminal such as a smartphone or a tablet computer. As shown in FIG. 1 to FIG. 3, the electronic device 1 includes an operation plate 2, a housing 3, an opposing member 4, a support member 5, and a piezoelectric sensor 13. The housing 3 is a box. The housing 3 has a rectangular shape when viewed in the vertical direction. However, the upper surface of the housing 3 is open. The opening of the housing 3 has a rectangular shape when viewed in the vertical direction. The operation plate 2 has a plate shape. The operation plate 2 has an upper main surface S11 and a lower main surface S12. The operation plate 2 has a rectangular shape with long sides extending in the front-rear direction and short sides extending in the left-right direction when viewed in the vertical direction. As a result, the operation plate 2 covers the opening of the housing 3. The operation plate 2 may include a touch panel, a fingerprint sensor, and a display. A part of the user's body or an operation member contacts the upper main surface S11 of the operation plate 2.

[0020] The operation plate 2 includes a first conductive part 21. As shown in FIG. 3, the first conductive part 21 is exposed on the lower main surface S12 of the operation plate 2. The first conductive part 21 is connected to the ground. The first conductive part 21 is, for example, a wiring layer or a ground conductor layer provided on the operation plate 2. The first conductive part 21 may be a metal plate, a metal foil, an electrode provided on glass, an electrode provided on a film, or a conductive cushion. The operation plate 2 and the housing 3 form a space inside. A battery, a circuit board, a CPU (Central Processing Unit), a frame, and the like (not shown) are provided in this space.

[0021] The facing member 4 has a facing surface S21 facing the lower main surface S12 of the operation plate 2. More specifically, the facing member 4 is disposed in a space formed by the operation plate 2 and the housing 3. The facing member 4 has an upper main surface (facing surface S21) and a lower main surface S22. The facing member 4 also includes a second conductive part 41. As shown in FIG. 3, the second conductive part 41 is exposed on the facing surface S21 of the facing member 4. The second conductive part 41 is connected to the ground. In this embodiment, the facing member 4 is a frame. However, the facing member 4 may be a circuit board, a battery, or the like. When the facing member 4 is a frame, the second conductive part 41 is, for example, a metal frame formed of a conductive material such as metal. When the facing member 4 is a battery, the second conductive part 41 is a ground for grounding provided on the surface of the facing member 4. When the facing member 4 is a circuit board, the second conductive part 41 is a wiring layer, a ground conductor layer, or the like.

[0022] The piezoelectric sensor 13 outputs a detection signal that detects the deformation of the operation plate 2. More specifically, the piezoelectric sensor 13 outputs a detection signal for detecting that the user has pressed the operation plate 2. That is, the piezoelectric sensor 13 outputs a detection signal according to the deformation caused in the operation plate 2 by the user pressing the operation plate 2. As shown in FIG. 2, the piezoelectric sensor 13 is provided on the lower main surface S12 of the operation plate 2. More specifically, the piezoelectric sensor 13 has a rectangular shape with long sides extending in the left-right direction when viewed in the up-down direction. The piezoelectric sensor 13 extends in the left-right direction at the center of the front-rear direction of the operation plate 2 when viewed in the up-down direction. The piezoelectric sensor 13 will be described below in detail with reference to FIG. 4.

[0023] The piezoelectric sensor 13 includes a piezoelectric film 14, an upper electrode 15a, a lower electrode 15b, a substrate 16, and adhesive layers 18 and 20. As shown in FIG. 4, the piezoelectric film 14 has a sheet shape. Therefore, the piezoelectric film 14 has an upper main surface S1 and a lower main surface S2. The length of the piezoelectric film 14 in the left-right direction is longer than the length of the piezoelectric film 14 in the front-rear direction. In this embodiment, the piezoelectric film 14 has a rectangular shape with long sides extending in the left-right direction when viewed in the up-down direction. The piezoelectric film 14 generates a charge according to the deformation amount of the piezoelectric film 14. In this embodiment, the piezoelectric film 14 is a PLA film. The piezoelectric film 14 will be described in more detail below.

[0024] The piezoelectric film 14 has a characteristic that the polarity of the electric charge generated when the piezoelectric film 14 is stretched in the left-right direction is opposite to the polarity of the electric charge generated when the piezoelectric film 14 is stretched in the front-back direction. Specifically, the piezoelectric film 14 is a film formed from a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA), particularly L-type polylactic acid (PLLA). PLLA made of a chiral polymer has a helical structure of the main chain. PLLA has a piezoelectricity in which the molecules are oriented by uniaxial stretching. The piezoelectric film 14 has a piezoelectric constant of d14. The uniaxial stretching direction (orientation direction) of the piezoelectric film 14 forms an angle of 45 degrees with respect to each of the front-back direction and the left-right direction. This 45 degrees includes, for example, an angle including about 45 degrees ±10 degrees. As a result, the piezoelectric film 14 generates an electric charge when the piezoelectric film 14 is stretched in the left-right direction or compressed in the left-right direction. For example, the piezoelectric film 14 generates a positive electric charge when stretched in the left-right direction. For example, when the piezoelectric film 14 is compressed in the left-right direction, it generates a negative charge. The magnitude of the charge depends on the amount of deformation of the piezoelectric film 14 due to expansion or compression. More precisely, the magnitude of the charge depends on the differential value of the amount of deformation of the piezoelectric film 14 due to expansion or compression.

[0025] The upper electrode 15a is a signal electrode. A detection signal is output from the upper electrode 15a. The upper electrode 15a is provided on the upper main surface S1 as shown in FIG. 1. The material of the upper electrode 15a is, for example, a conductive polymer such as PEDOT. The upper electrode 15a may be disposed on the substrate 16 so that the lower main surface of the upper electrode 15a faces the upper main surface S1, and the piezoelectric film 14 and the substrate 16 may be bonded by an adhesive layer 18. In this case, the upper electrode 15a is formed on the substrate 16, for example.

[0026] The lower electrode 15b is a ground electrode. The lower electrode 15b is connected to the ground. As shown in FIG. 1, the lower electrode 15b is provided on the lower main surface S2. The material of the lower electrode 15b is, for example, a conductive tape or a conductive polymer such as PEDOT. An adhesive, a double-sided tape, or the like may be present between the piezoelectric film 14 and the upper electrode 15a.

[0027] The substrate 16 is provided on the upper electrode 15a, and by holding the piezoelectric film 14, the upper electrode 15a, and the lower electrode 15b, the substrate 16 is deformed together with the piezoelectric film 14. The substrate 16 has a sheet shape. The substrate 16 has an upper main surface and a lower main surface. The length of the substrate 16 in the left-right direction is longer than the length of the substrate 16 in the front-rear direction. In this embodiment, the substrate 16 has a rectangular shape having long sides extending in the left-right direction when viewed in the up-down direction. The long sides of the substrate 16 are longer than the long sides of the piezoelectric film 14, the long sides of the upper electrode 15a, and the long sides of the lower electrode 15b. The short sides of the substrate 16 are longer than the short sides of the piezoelectric film 14, the short sides of the upper electrode 15a, and the short sides of the lower electrode 15b. The piezoelectric film 14, the upper electrode 15a, and the lower electrode 15b are arranged in a region surrounded by the outer edge of the substrate 16 when viewed in the up-down direction.

[0028] The material of the base material 16 is, for example, polyurethane or PET. It may also be formed of a flexible substrate or a printed wiring board.

[0029] As shown in FIG. 3, the adhesive layer 18 fixes the piezoelectric film 14, the upper electrode 15a, and the lower electrode 15b to the substrate 16. More specifically, the adhesive layer 18 is provided on the lower main surface of the substrate 16. The adhesive layer 18 covers a part of the lower main surface of the substrate 16. The adhesive layer 18 also covers the entire upper main surface of the upper electrode 15a. The outer edge of the adhesive layer 18 is surrounded by the outer edge of the substrate 16 when viewed in the up-down direction. The adhesive layer 18 bonds the upper electrode 15a and the substrate 16. As a result, the deformation of the substrate 16 is transmitted to the piezoelectric film 14. The material of the adhesive layer 18 is, for example, a double-sided tape, a thermosetting adhesive, or a thermoplastic adhesive.

[0030] The adhesive layer 20 is provided on the upper main surface of the base material 16. The adhesive layer 20 fixes the base material 16 to the operation plate 2. In this embodiment, the adhesive layer 20 fixes the base material 16 to the lower main surface S12 of the operation plate 2. The material of the adhesive layer 20 is, for example, a double-sided tape, a thermosetting adhesive, or a thermoplastic adhesive.

[0031] As shown in FIG. 3, the support member 5 is in contact with the lower main surface S12 of the operation plate 2 and the opposing surface S21 of the opposing member 4. More specifically, the support member 5 has a columnar shape extending in the up-down direction. In this embodiment, the support member 5 has a cylindrical shape. The support member 5 is in contact with the first conductive portion 21 and the second conductive portion 41. The upper end of the support member 5 is in contact with the first conductive portion 21. The lower end of the support member 5 is in contact with the second conductive portion 41. In addition, the support member 5 is conductive. As a result, the support member 5 electrically connects the first conductive portion 21 connected to the ground and the second conductive portion 41 connected to the ground.

[0032] Furthermore, the support member 5 is an elastic body. Therefore, the support member 5 is elastically deformed when it receives an external force. Here, the natural length of the support member 5 is slightly longer than the distance between the lower main surface S12 and the opposing surface S21 in the vertical direction. The natural length of the support member 5 is the length of the support member 5 when the support member 5 is not in contact with the lower main surface S12 and the opposing surface S21. Therefore, when the support member 5 is in contact with the lower main surface S12 and the opposing surface S21, the support member 5 is slightly compressed in the vertical direction. Therefore, the support member 5 applies an upward force of 2N or less to the operation plate 2. The material of such a support member 5 is, for example, a metal, a conductive resin, or the like.

[0033] Next, the arrangement of the support member 5 will be described with reference to FIG. 1. The support member 5 is 10 mm or more away from the outer edge of the piezoelectric sensor 13 when viewed in the up-down direction. Furthermore, the support member 5 is 10 mm or more away from the outer edge of the operation plate 2 when viewed in the up-down direction. Therefore, the support member 5 is arranged in the arrangement areas A1 and A2 hatched in FIG. 1. The arrangement area A1 is located in front of the piezoelectric sensor 13. The arrangement area A2 is located behind the piezoelectric sensor 13. In this embodiment, the support member 5 is arranged behind the center in the left-right direction of the piezoelectric sensor 13. Therefore, the support member 5 is arranged in the arrangement area A2.

[0034] (experiment) The inventors of the present application conducted the experiments described below in order to clarify the effects of the electronic device 1. Figure 5 is a cross-sectional view of an experimental device 100. First, the experimental device 100 will be described.

[0035] The experimental device 100 includes waterproof double-sided tapes 201L and 201R and housings 202L and 202R. The left end of the operation plate 2 is fixed to the housing 202L with the waterproof double-sided tape 201L. The right end of the operation plate 2 is fixed to the housing 202R with the waterproof double-sided tape 201R. The housings 202L and 202R are made of aluminum. The housings 202L and 202R correspond to the housing 3 of the electronic device 1.

[0036] The operation plate 2 includes a glass plate 101, an ultraviolet curing adhesive 102, a PET film 103, a glass plate 104, an adhesive 105, and a stainless steel plate 106. The glass plate 101, the ultraviolet curing adhesive 102, the PET film 103, the glass plate 104, the adhesive 105, and the stainless steel plate 106 are layered in this order from top to bottom. The operation plate 2 corresponds to a display and a cover glass. The operation plate 2 and the housings 202L and 202R form a rectangular parallelepiped box.

[0037] The entire surface of the piezoelectric sensor 13 is fixed to the lower main surface of the stainless steel plate 106 with an adhesive. The thickness of the adhesive is 75 μm. The elastic modulus of the adhesive is 2 MPa. The center of the piezoelectric sensor 13 in the left-right direction coincides with the center of the operation plate 2 in the left-right direction. The long sides of the piezoelectric sensor 13 are parallel to the short sides of the operation plate 2.

[0038] The conditions of the experimental apparatus 100 are described below.

[0039] Dimensions of glass plate 101: 143.5mm x 66.6mm Thickness of glass plate 101: 0.7 mm UV-curable adhesive 102 dimensions: 133.9mm x 64.1mm Thickness of UV-curable adhesive 102: 0.1 mm Dimensions of PET film 103: 133.9mm x 64.1mm Thickness of PET film 103: 0.15 mm Dimensions of glass plate 104: 133.9 mm x 64.1 mm Thickness of glass plate 104: 0.5 mm Adhesive 105 dimensions: 133.9mm x 64.1mm Adhesive 105 thickness: 0.2mm Dimensions of stainless steel plate 106: 133.9mm x 64.1mm Thickness of stainless steel plate 106: 0.15 mm Dimensions of piezoelectric sensor 13: 48mm x 10mm Waterproof double-sided tape 201L, 201R thickness: 0.35mm Elastic modulus of waterproof double-sided tape 201L, 201R: 2MPa Dimensions of housing 202L, 202R: 145.5mm x 68.6mm x 10mm Thickness of housing 202L, 202R: 2mm Shape of the housings 202L and 202R: Hollow rectangular parallelepiped with an open top Material of the support member 5: Silicone sponge Product name of support member 5: ZSR2101 Manufacturer: Hakko Electric Shape of the support member 5: a rectangular parallelepiped with each side having a length of 10 mm [Experiment 1] The inventors of the present application conducted Experiment 1 to clarify that it is preferable that the support member 5 is spaced 10 mm or more from the outer edge of the piezoelectric sensor 13 when viewed in the vertical direction.

[0040] The inventor applied a downward force to the upper main surface S11 of the operation plate 2. Specifically, the inventor applied a downward force to the center (position P1) of the piezoelectric sensor 13 in the left-right direction. The inventor applied the force by lowering a 100 g weight at a speed of 2 mm / s from a position 0.3 mm above the upper main surface S11 of the operation plate 2. The inventor set the magnitude of the force applied by the support member 5 to the operation plate 2 to 2 N.

[0041] In addition, in experiment 1, the inventor placed the support member 5 behind position P1. The inventor changed the distance D1 between the support member 5 and the piezoelectric sensor 13 to three values: 10 mm, 20 mm, and 30 mm. The inventor then measured the strength of the detection signal from the piezoelectric sensor 13. FIG. 7 is a graph showing the results of experiment 1. The horizontal axis represents the distance D1. The vertical axis represents the strength of the detection signal from the piezoelectric sensor 13.

[0042] As shown in Fig. 7, when the distance D1 becomes smaller than 10 mm, the strength of the detection signal decreases. This means that the support member 5 prevents the piezoelectric sensor 13 from deforming. Therefore, from Experiment 1, it is preferable that the support member 5 is 10 mm or more away from the outer edge of the piezoelectric sensor 13 when viewed in the vertical direction. This enables the electronic device 1 to improve the detection sensitivity of the piezoelectric sensor 13.

[0043] [Experiment 2] The inventors of the present application conducted Experiment 2 in order to clarify that it is preferable that the support member 5 is spaced 10 mm or more from the outer edge of the operation plate 2 when viewed in the up-down direction.

[0044] The inventor applied a downward force to the upper main surface S11 of the operation plate 2. Specifically, the inventor applied the downward force to position P2, which is 30 mm behind and 30 mm to the right of the center of the piezoelectric sensor 13 in the left-right direction. Position P2 is located near the right end (right long side) of the operation plate 2. The inventor applied the force by lowering a 100 g weight at a speed of 2 mm / s from a position 0.3 mm above the upper main surface S11 of the operation plate 2. The inventor set the magnitude of the force applied by the support member 5 to the operation plate 2 to 2 N.

[0045] In addition, in experiment 2, the inventor placed the support member 5 to the left of position P2. The inventor changed the distance D2 between the support member 5 and the right end (right long side) of the operation plate 2 to 10 mm, 20 mm, and 30 mm. The inventor then measured the strength of the detection signal of the piezoelectric sensor 13. FIG. 9 is a graph showing the results of experiment 2. The horizontal axis represents the distance D2. The vertical axis represents the strength of the detection signal of the piezoelectric sensor 13.

[0046] As shown in Fig. 9, it can be seen that the strength of the detection signal decreases when the distance D2 is smaller than 10 mm. This means that the support member 5 prevents the piezoelectric sensor 13 from deforming when the user presses the end of the operation plate 2. Therefore, from Experiment 2, it is preferable that the support member 5 is 10 mm or more away from the outer edge of the operation plate 2 when viewed in the up-down direction. This enables the electronic device 1 to improve the detection sensitivity of the piezoelectric sensor 13.

[0047] [Experiment 3] The inventors of the present application conducted Experiment 3 to clarify that it is preferable for the support member 5 to apply an upward force of 2 N or less to the operation plate 2, and that it is preferable for the pressure that the support member 5 applies to the lower main surface S12 of the operation plate 2 to be 0.02 MPa or less. Fig. 10 is a top view of the experimental device 100. Fig. 11 is a graph showing the experimental results of Experiment 3.

[0048] The inventor applied a downward force to the upper main surface S11 of the operation plate 2. Specifically, the inventor applied a downward force to the center (position P1) in the left-right direction of the piezoelectric sensor 13. The inventor applied the force by lowering a 100 g weight from a position 0.3 mm above the upper main surface S11 of the operation plate 2 at a speed of 2 mm / s.

[0049] In addition, in Experiment 3, the inventor placed the support member 5 behind the position P1. The inventor set the distance D1 between the support member 5 and the piezoelectric sensor 13 to 30 mm. At this time, the inventor changed the magnitude F of the force applied by the support member 5 to the operation plate 2 from 0.5 N to 2.5 N. Then, the inventor measured the intensity of the detection signal of the piezoelectric sensor 13. FIG. 11 is a graph showing the experimental results of Experiment 3. The horizontal axis indicates the magnitude of the force F. The vertical axis indicates the intensity of the detection signal of the piezoelectric sensor 13. The magnitude of the force F was measured by the following procedure. The inventor pressed the operation plate 2 downward against the housings 202L and 202R. Then, the inventor measured the magnitude of the force F by a force gauge when the upper main surface S11 of the operation plate 2 and the upper ends of the housings 202L and 202R were positioned at the same height in the vertical direction.

[0050] As shown in Fig. 11, it can be seen that when the magnitude of force F becomes larger than 2N, the strength of the detection signal decreases. This means that the support member 5 inhibits the deformation of the piezoelectric sensor 13. Therefore, based on Experiment 3, it is preferable that the support member 5 applies an upward force of 2N or less to the operation plate 2. This enables the electronic device 1 to improve the detection sensitivity of the piezoelectric sensor 13.

[0051] The shape of the support member 5 is a rectangular parallelepiped with each side having a length of 10 mm. Therefore, when the support member 5 applies a force of 2 N, the support member 5 applies a pressure of 0.02 MPa or less. Therefore, the pressure that the support member 5 applies to the lower main surface S12 of the operation plate 2 is preferably 0.02 MPa or less.

[0052] [Experiment 4] The inventors of the present application conducted Experiment 4 to clarify that the electronic device 1 including the support member 5 suppresses variation in sensitivity of the piezoelectric sensor 13 depending on the position at which the operation plate 2 is pressed. Fig. 12 is a top view of the experimental device 100. Points 1 to 25 in Fig. 12 indicate the positions of the upper main surface S11 of the operation plate 2.

[0053] The inventor applied a downward force to the upper main surface S11 of the operation plate 2. Specifically, the inventor applied a downward force to each of points 1 to 25 in Fig. 12. The inventor applied the force by lowering a 100 g weight from a position 0.3 mm above the upper main surface S11 of the operation plate 2 at a speed of 2 mm / s.

[0054] In addition, in Experiment 4, the inventor of the present application conducted an experiment using an experimental apparatus 100 including a support member 5 and an experimental apparatus 100 not including a support member 5. In the experimental apparatus 100 including the support member 5, the inventor of the present application placed the support member 5 behind the position P1. The inventor of the present application set the distance D1 between the support member 5 and the piezoelectric sensor 13 to 30 mm. The inventor of the present application set the magnitude of the force applied by the support member 5 to the operation plate 2 to 2 N. The inventor of the present application then measured the strength of the detection signal of the piezoelectric sensor 13 of each of the experimental apparatus 100 including the support member 5 and the experimental apparatus 100 not including the support member 5. FIG. 13 is a graph showing the experimental results of Experiment 3. The horizontal axis indicates points 1 to 25. The vertical axis indicates the strength of the detection signal of the piezoelectric sensor 13.

[0055] 13, in the electronic device 1 not including the support member 5, it is understood that there is a large difference between the intensity of the detection signal when the user presses the center of the operation plate 2 in the left-right direction (particularly, points 8, 13, 18) and the intensity of the detection signal when the user presses a part other than the center of the operation plate 2 in the left-right direction. On the other hand, as shown in FIG. 13, in the electronic device 1 including the support member 5, it is understood that there is a small difference between the intensity of the detection signal when the user presses the center of the operation plate 2 in the left-right direction (particularly, points 8, 13, 18) and the intensity of the detection signal when the user presses a part other than the center of the operation plate 2 in the left-right direction. In this way, by including the support member 5 in the electronic device 1, the variation in sensitivity of the piezoelectric sensor 13 depending on the position at which the operation plate 2 is pressed is suppressed.

[0056] As shown in FIG. 13, the outputs of points 17, 18, and 19 behind the operation plate 2 are also reduced. This is because the support member 5 is disposed behind the piezoelectric sensor 13. The experimental device 100 has a structure that is symmetrical in the front-to-rear direction. Therefore, when the support member 5 is disposed in front of the piezoelectric sensor 13, it is clear that the outputs of points 7, 8, and 9 located in front of the operation plate 2 will decrease. Therefore, it is preferable that the support member 5 is disposed in two locations, in front of and behind the piezoelectric sensor 13. This makes it possible to make the outputs of points 7, 8, and 9 located in front of the operation plate 2 and the outputs of points 17, 18, and 19 located behind the operation plate 2 approximately the same.

[0057] (Other embodiments) The electronic device 1 according to the present invention is not limited to the electronic device 1, and can be modified within the scope of the gist thereof.

[0058] In the electronic device 1, the support member 5 does not need to be spaced 10 mm or less from the outer edge of the operation plate 2 when viewed in the vertical direction.

[0059] In the electronic device 1, the operation plate 2 does not have to have a rectangular shape when viewed in the up-down direction.

[0060] In the electronic device 1, the piezoelectric sensor 13 does not have to extend in the left-right direction at the center in the front-rear direction of the operation plate 2 when viewed in the up-down direction. The piezoelectric sensor 13 may be disposed in front of or behind the center in the front-rear direction of the operation plate 2. The piezoelectric sensor 13 may also extend in the front-rear direction.

[0061] In addition, in the electronic device 1, either one or both of the first conductive portion 21 and the second conductive portion 41 may not be present.

[0062] In the experimental apparatus 100, a spring may be used as the support member 5. The magnitude of the force F is adjusted by adjusting the spring constant. In this case, the spring constant is, for example, 0.4 or more and 1 or less.

[0063] In the electronic device 1, the piezoelectric film 14 may be a PVDF (polyvinylidene fluoride) film.

[0064] It should be noted that it is sufficient that the first conductive portion 21 and / or the second conductive portion 41 is connected to the ground in the electronic device 1. Therefore, the first conductive portion 21 or the second conductive portion 41 does not have to be connected to the ground. [Explanation of symbols]

[0065] 1:Electronic equipment 2: Operation board 3: Housing 4: Opposing parts 5: Support member 13: Piezoelectric sensor 14: Piezoelectric film 15a: Upper electrode 15b: Lower electrode 16: Base material 18,20: Adhesive layer 21: First conductive part 41: Second conductive part A1,A2: Placement area

Claims

1. An operation plate having an upper main surface and a lower main surface, wherein a part of a user's body or an operation member comes into contact with the upper main surface of the operation plate; a piezoelectric sensor provided on the lower main surface of the operation plate, the piezoelectric sensor detecting deformation of the operation plate and outputting a detection signal; an opposing member having an opposing surface facing the lower main surface of the operation plate; a support member in contact with the lower main surface of the operation plate and the opposing surface of the opposing member; Equipped with the support member is spaced from an outer edge of the piezoelectric sensor by 10 mm or more when viewed in a vertical direction, The support member applies an upward force of 2 N or less to the operation plate. electronic equipment.

2. The support member is spaced 10 mm or more from the outer edge of the operation plate when viewed in the vertical direction.

2. The electronic device according to claim 1.

3. The operation plate has a rectangular shape having a long side extending in a front-rear direction and a short side extending in a left-right direction when viewed in a vertical direction, The piezoelectric sensor extends in the left-right direction at the center of the front-rear direction of the operation plate when viewed in the up-down direction.

3. The electronic device according to claim 1 or 2.

4. A first conductive portion is exposed on the lower main surface of the operation plate, a second conductive portion is exposed on the opposing surface of the opposing member, the first conductive portion and / or the second conductive portion are connected to ground, The support member is in contact with the first conductive portion and the second conductive portion.

4. The electronic device according to claim 1.

5. The support member is disposed in two locations, in front of and behind the piezoelectric sensor.

5. The electronic device according to claim 1.

6. The pressure applied by the support member to the lower main surface of the operation plate is 0.02 MPa or less.

6. The electronic device according to claim 1.

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