Deformation detection sensor

Abstract

Provided is a deformation detection sensor capable of outputting equal output values even when press-fit positions are different. This deformation detection sensor is provided with: a holding unit which is connected to an operation panel for receiving a press-in operation by a user, and which holds the operation panel; and a piezoelectric film that is connected to the holding portion and detects deformation of the holding portion, the holding portion having: a first portion that is connected to the housing; a second portion connected to the operation panel; and a beam portion that connects the first portion and the second portion and has elasticity, the piezoelectric film is connected across the first portion and the second portion, and the piezoelectric film includes a first piezoelectric film and a second piezoelectric film stacked on each other. When the first piezoelectric film and the second piezoelectric film are bent in the lamination direction, the first piezoelectric film and the second piezoelectric film are polarized to equal potentials with different polarities.

Description

Technical Field

[0001] The utility model relates to deformation detection for detecting the deformation of an object. Background Art

[0002] The input device disclosed in Patent Document 1 includes an input pad whose periphery is held by a frame, etc. The input device receives user operations by applying force to the input pad. The input device detects and measures the position and magnitude of the force applied to the input pad using multiple sensors.

[0003] In the input device disclosed in Patent Document 1, multiple sensors are positioned near the corners of a rectangular, flat input plate. These sensors deform according to the force applied to the input plate. The input device disclosed in Patent Document 1 measures the magnitude and position of the force applied to the input plate based on the outputs of these sensors.

[0004] In addition, the vibration device of Patent Document 2 includes a vibration unit and a touch panel. When a user presses the touch panel, the vibration unit transmits vibration to the user. The vibration unit includes a flat vibration portion, a frame-shaped frame member, and a beam (support portion) connecting the vibration portion and the frame member. The frame member and the vibration portion are connected via a piezoelectric film. The vibration device of Patent Document 2 applies a voltage to the piezoelectric film, causing the piezoelectric film to expand and contract, thereby vibrating the vibration portion.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2008-546113

[0008] Patent Document 2: Japanese Patent Application No. 2020 / 213477 Utility Model Content

[0009] Problems to be solved by utility models

[0010] In the configuration of Patent Document 1, in order to detect the position and magnitude of a force applied to the input plate (touch panel) using a plurality of sensors, at least two sensors are required.

[0011] On the other hand, it is considered that if the voltage generated in the piezoelectric film of Patent Document 2 is detected, deformation of the vibration portion can be detected, and the touch panel can function as a deformation detection sensor that detects deformation of the pressed object.

[0012] However, in the structure of Patent Document 2, a single sensor is connected to the vibrating portion and the frame-shaped member. Therefore, the deformation of the piezoelectric film varies depending on where a force is applied to the input pad when viewed from above. Specifically, if the user presses a location near the connection between the piezoelectric film and the vibrating portion, the vertical displacement of the vibrating portion at that connection becomes greater, and the deflection of the piezoelectric film increases, compared to when the user presses a location farther from the connection.

[0013] Thus, the deformation of the piezoelectric film caused by pressing in the vertical direction relative to the touch panel varies depending on the position of the pressing in a plan view. Therefore, even when the pressing amount is the same, the deformation detection sensor outputs different output values ​​depending on the pressing position.

[0014] An object of the present invention is to provide a deformation detection sensor that outputs a uniform output value even when the pressed positions are different.

[0015] Solutions for solving problems

[0016] The deformation detection sensor includes: a holding portion connected to an operating panel that receives a user's press-in operation and holds the operating panel; and a piezoelectric film connected to the holding portion and detecting deformation of the holding portion. The holding portion includes: a first portion connected to a frame; a second portion connected to the operating panel; and a beam portion connecting the first and second portions and having elasticity. The piezoelectric film is connected across the first and second portions. The piezoelectric film includes a first piezoelectric film and a second piezoelectric film stacked on each other. When bent in the stacking direction, the first piezoelectric film and the second piezoelectric film are polarized to the same potential with different polarities.

[0017] Preferably, the first piezoelectric film and the second piezoelectric film have the same shape and size in a plan view.

[0018] Preferably, the length of the first piezoelectric film in the stacking direction is set to the thickness of the first piezoelectric film, and the length of the second piezoelectric film in the stacking direction is set to the thickness of the second piezoelectric film, and the first ratio which is the ratio of the thickness of the first piezoelectric film to the dielectric constant of the first piezoelectric film and the second ratio which is the ratio of the thickness of the second piezoelectric film to the dielectric constant of the second piezoelectric film are the same.

[0019] Preferably, the piezoelectric constant of the first piezoelectric film is the same as the piezoelectric constant of the second piezoelectric film.

[0020] Preferably, a product of a piezoelectric constant of the first piezoelectric film and a thickness of the first piezoelectric film and a product of a piezoelectric constant of the second piezoelectric film and a thickness of the second piezoelectric film are the same.

[0021] In addition, the deformation detection sensor includes: a holding portion connected to an operation panel that receives a user's pressing operation and holds the operation panel; and a piezoelectric film connected to the holding portion and detecting deformation of the holding portion. The holding portion includes: a first portion connected to a frame; a second portion connected to the operation panel; and a plurality of beam portions that connect the first portion and the second portion and have elasticity. The piezoelectric film is connected across the first portion and the second portion. The direction from the first connection position where the first portion is connected to the piezoelectric film toward the second connection position where the second portion is connected to the piezoelectric film is defined as a first direction. The plurality of beam portions include: a first beam portion provided at a position close to the second connection position along the first direction; and a second beam portion provided at a position farther from the second connection position than the distance between the first beam portion and the second connection position. When the normal direction of the connection surface of the holding portion connected to the operation panel is set as the thickness direction, the first beam portion is less likely to deform in the thickness direction than the second beam portion.

[0022] Preferably, the first thickness, which is the length of the first beam portion in the thickness direction, and the second thickness, which is the length of the second beam portion in the thickness direction, are the same; a direction parallel to the connecting surface and orthogonal to the first direction is set as the second direction; the length of the first beam portion in the second direction and the length of the second beam portion in the second direction are the same; and when the length of the first beam portion in the first direction is set as the first width of the first beam portion and the length of the second beam portion in the first direction is set as the second width of the second beam portion, the first width is larger than the second width.

[0023] Preferably, the first thickness, which is the length of the first beam portion in the thickness direction, and the second thickness, which is the length of the second beam portion in the thickness direction, are the same. A direction parallel to the connection surface and orthogonal to the first direction is set as a second direction. The length of the first beam portion in the second direction and the length of the second beam portion in the second direction are different. When the length of the first beam portion in the first direction is set as the first width of the first beam portion and the length of the second beam portion in the first direction is set as the second width of the second beam portion, the following formula 1 is satisfied: Formula 1: (W1 3 ×t) / L1 3 =(W2 3 ×t) / L2 3 .

[0024] Effect of utility model

[0025] A deformation detection sensor according to one aspect of the present invention can output a uniform output value even when the pressed positions are different. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an exploded perspective view of an electronic device 100 including the deformation detection sensor 10 according to the first embodiment.

[0027] Figure 2 yes Figure 1 Cross-sectional view at line AA.

[0028] Figure 3 It is a bottom view of the deformation detection sensor 10 according to the first embodiment.

[0029] Figure 4 This is a side view of the piezoelectric film 4 as viewed from the front-back direction in the first embodiment.

[0030] Figure 5 is a side view of the curved piezoelectric film 4 .

[0031] Figure 6 It is a cross-sectional view showing an example of a depressed position of the touch panel 1 as viewed from the front-back direction Z1.

[0032] Figure 7 This is a cross-sectional view showing an example of deformation of the deformation detecting portion when point A is pressed downward.

[0033] Figure 8 This is a cross-sectional view showing an example of deformation of the deformation detecting portion when point B is pressed downward.

[0034] Figure 9 4 is a reference diagram showing an example of the output value of the piezoelectric film 4 .

[0035] Figure 10 : is a reference diagram showing an example of output values ​​of a piezoelectric film of a reference example.

[0036] Figure 11 This is an exploded perspective view of an electronic device 100A including the deformation detection sensor 10A according to the second embodiment.

[0037] Figure 12 This is a side view of the piezoelectric film 4A as viewed from the front-back direction Z1 in the second embodiment.

[0038] Figure 13 It is a bottom view of the deformation detection sensor 10A according to the second embodiment.

[0039] Figure 14 yes Figure 13 Cross-sectional view at line BB.

[0040] Figure 154 is a reference diagram showing output values ​​of the piezoelectric film 4A when point A is pressed and when point B is pressed.

[0041] Figure 16 This is a side view of a member showing an example of the deflection of the member.

[0042] Figure 17 yes Figure 16 Cross-sectional view at line CC. DETAILED DESCRIPTION

[0043] [Implementation Method 1]

[0044] [Structure of deformation detection sensor]

[0045] Hereinafter, the structure of the deformation detection sensor 10 according to one embodiment of the present invention will be described with reference to the drawings. Figure 1 This is an exploded perspective view of an electronic device 100 including the deformation detection sensor 10 according to the first embodiment. Figure 2 yes Figure 1 Cross-sectional view at line AA. Figure 3 It is a bottom view of the deformation detection sensor 10 according to the first embodiment.

[0046] The electronic device 100 includes a touch panel 1, a housing 2, a deformation detection sensor 10, and an actuator 5. The touch panel 1 in this example is an example of an operation panel of the present invention.

[0047] In this specification, directions are defined as follows. The normal direction of the touch panel 1 formed in a flat plate shape is defined as the up-down direction Y1. In addition, the touch panel 1 has a rectangular shape when viewed from above. The long side direction when viewing the touch panel 1 from above is defined as the left-right direction X1, and the short side direction when viewing the touch panel 1 from the up-down direction Y1 is defined as the front-back direction Z1. The up-down direction Y1, the left-right direction X1, and the front-back direction Z1 are orthogonal to each other. In addition, the vertical direction refers to the direction from top to bottom in the up-down direction Y1. In addition, the horizontal direction refers to the direction orthogonal to the vertical direction. Viewing from above means viewing from top to bottom. The left-right direction X1 mentioned in this example corresponds to the first direction of the present invention. In addition, the up-down direction Y1 mentioned in this example corresponds to the second direction of the present invention. In addition, in the drawings, "B" represents back. In the drawings, "F" represents front. In the drawings, "D" represents down. In the drawings, "U" represents up.

[0048] In addition, the definition of direction in this specification is an example. Therefore, the direction of the deformation detection sensor 10 and the electronic device 100 including the deformation detection sensor 10 when actually used does not need to be consistent with the direction in this specification. Figure 1 In the same way, the up-down direction Y1 can also be reversed. Figure 1In the case of Figure 1 The front-to-back direction Z1 can also be reversed.

[0049] like Figure 1 As shown, electronic device 100 includes a deformation detection sensor 10. Furthermore, electronic device 100 is, for example, a smartphone or a laptop-type personal computer, and includes a touch panel 1. Electronic device 100 provides tactile feedback to the user when a force is applied to touch panel 1. In this example, the force applied to touch panel 1 is a force that presses touch panel 1.

[0050] The touch panel 1 includes, for example, a capacitive touch sensor. The capacitive touch sensor detects a user's contact with the touch panel 1. The touch panel 1 also receives a pressing operation from the user. The deformation detection sensor 10 detects the user's pressing operation.

[0051] The frame 2 is a rigid body having a flat frame shape. The frame 2 is formed, for example, from SUS (Steel Use Stainless Steel). The frame 2 is formed to be longitudinally elongated in the left-right direction X1. The frame 2 has an opening Op1 longitudinally elongated in the left-right direction X1 when viewed from above. The opening Op1 is larger than the touch panel 1 when viewed from above. The touch panel 1 is exposed from the frame 2 through the opening Op1.

[0052] The deformation detection sensor 10 includes a holding portion 3 and a piezoelectric film 4 .

[0053] The holding portion 3 has a flat plate shape. The holding portion 3 is formed of, for example, a single metal plate. The holding portion 3 is formed of, for example, SUS (Steel Use Stainless Steel). The holding portion 3 is connected to the touch panel 1 and holds the touch panel 1. More specifically, the holding portion 3 includes, when viewed from above, a first portion 31 as an outer frame portion, a second portion 32 as an inner frame portion, and a plurality of (in the) connecting portions 1 and 2, 31. Figure 1 The first portion 31, the second portion 32, and the plurality of beam portions 33 are integrally formed by, for example, punching out a single SUS plate.

[0054] like Figure 2 As shown, the first portion 31 is connected to the lower surface of the frame body 2 in the vertical direction Y1.

[0055] The second portion 32 is connected to the lower surface of the touch panel 1 in the up-down direction Y1.

[0056] The four beams 33 have elasticity. The four beams 33 each have a rectangular shape when the holding portion 3 is viewed from above (see Figure 1The four beams 33 are provided near each corner of the second portion 32. When a force is applied to the touch panel 1 due to the elastic deformation of the four beams 33, the second portion 32 deforms relative to the first portion 31, for example, at least in the vertical direction Y1. The deformation of the beams 33 in the vertical direction Y1 and the horizontal direction X1 will be described later.

[0057] Furthermore, when the four beams 33 apply a force to the touch panel 1 , the second portion 32 may be deformed in the up-down direction Y1 and the left-right direction X1 relative to the first portion 31 .

[0058] like Figure 3 As shown in FIG. 1 , the piezoelectric film 4 is vertically elongated in the left-right direction X1 when viewed from above and has a film shape. The piezoelectric film 4 is disposed below the holding portion 3. The piezoelectric film 4 is connected across the right end of the first portion 31 and the right end of the second portion 32 of the holding portion 3. More specifically, as shown in FIG. Figure 2 and Figure 3 As shown, a first connection point 43, which is the right end of the piezoelectric film 4, is connected to a portion 31A of the first portion 31 of the holder 3. Furthermore, a second connection point 44, which is the left end of the piezoelectric film 4, is connected to a portion 32A of the second portion 32 of the holder 3. The piezoelectric film 4 deforms in response to a force applied to the touch panel 1 by a user. Details of the piezoelectric film 4 will be described below.

[0059] In this example, the portion 31A is the right end side in the left-right direction X1 of the first portion 31. The portion 32A is the right end side in the left-right direction X1 of the second portion 32. The portion 32B is the left end side in the left-right direction X1 of the second portion 32.

[0060] like Figure 1 As shown in FIG. 1 , the actuator 5 is vertically elongated in the left-right direction X1 when viewed from above and has a membrane shape. The actuator 5 is connected to the first portion 31 and the second portion 32 of the holding portion 3. More specifically, as shown in FIG. Figure 3 As shown, the actuator 5 is connected to the portion 31A of the first portion 31 at the right end in the left-right direction X1. Also, the actuator 5 is connected to the portion 32B of the second portion 32 at the left end in the left-right direction X1.

[0061] The actuator 5 includes a piezoelectric body. More specifically, the actuator 5 includes a piezoelectric film and a first electrode portion 51 and a second electrode portion 52 disposed on both main surfaces (the upper surface and the lower surface) of the piezoelectric film. The first electrode portion 51 and the second electrode portion 52 are each a metal coating film formed by vapor deposition, such as Cu, Al, or Ni.

[0062] The actuator 5 is connected to a drive circuit (not shown), for example. The drive circuit applies an AC voltage to the first electrode portion 51 and the second electrode portion 52 of the piezoelectric film of the actuator 5 when the deformation detection sensor 10 detects a press-in operation on the touch panel 1. By applying an AC voltage to the first electrode portion 51 and the second electrode portion 52, the piezoelectric film of the actuator 5 is expanded and contracted in the left-right direction X1. For example, the actuator 5 is extended in the left-right direction X1 by applying a positive voltage. On the other hand, for example, the actuator 5 is contracted in the left-right direction X1 by applying a negative voltage. The actuator 5 is connected to the second part 32, thereby vibrating the second part 32. The retaining portion 3 transmits vibration to the touch panel 1 through the vibration of the second part 32. Thus, the electronic device 100 provides tactile feedback to the user.

[0063] [Detailed Description of Piezoelectric Film 4]

[0064] Reference Figure 4 and Figure 5 , the piezoelectric film 4 is described. Figure 4 This is a side view of the piezoelectric film 4 as viewed from the front-back direction in the first embodiment. Figure 5 is a side view of the curved piezoelectric film 4 .

[0065] like Figure 4 As shown, the piezoelectric film 4 includes a first piezoelectric film 41 and a second piezoelectric film 42 stacked on each other along the up-down direction Y1. The first piezoelectric film 41 and the second piezoelectric film 42 are configured so as to be polarized with different polarities and equal potentials when bent (flexed) in the stacking direction. In other words, the first piezoelectric film 41 and the second piezoelectric film 42 are configured so as to generate opposite charges to each other and generate opposite potentials in the stacking direction. In addition, when the first piezoelectric film 41 and the second piezoelectric film 42 generate opposite charges to each other and the capacitance of the first piezoelectric film 41 and the capacitance of the second piezoelectric film 42 are the same or approximately the same, opposite potentials are generated. In addition, the stacking direction is the same as the up-down direction Y1 mentioned in this example.

[0066] The first piezoelectric film 41 and the second piezoelectric film 42 will be described in detail.

[0067] The first piezoelectric film 41 and the second piezoelectric film 42 are identical piezoelectric films. Each of the first and second piezoelectric films 41 and 42 is a rectangular film made of, for example, polyvinylidene fluoride (PVDF). PVDF exhibits piezoelectricity. Each of the first and second piezoelectric films 41 and 42 has a piezoelectric constant of d31.

[0068] In this example, the thickness ts1 of the first piezoelectric film 41 and the thickness ts2 of the second piezoelectric film 42 are the same length. For example, the thickness ts1 of the first piezoelectric film 41 and the thickness ts2 of the second piezoelectric film 42 are 30 μm. Furthermore, the first piezoelectric film 41 and the second piezoelectric film 42 have the same shape and size when viewed from above. In this example, the first piezoelectric film 41 and the second piezoelectric film 42 have a rectangular shape that is elongated along the left-right direction X1 when viewed from above.

[0069] The first piezoelectric film 41 and the second piezoelectric film 42 are respectively on the front and back (on Figure 4 Electrode portions are formed on the upper surface and the lower surface of the piezoelectric film 41. The first piezoelectric film 41 has a first electrode portion P11 formed on the upper surface. In addition, the first piezoelectric film 41 has a second electrode portion P12 formed on the lower surface. Furthermore, the second piezoelectric film 42 has a first electrode portion P21 formed on the upper surface. In addition, the second piezoelectric film 42 has a second electrode portion P22 formed on the lower surface. The first electrode portion P11, the second electrode portion P12, the first electrode portion P21, and the second electrode portion P22 are metal films such as Cu, Al, Ni, etc. formed by vapor deposition.

[0070] Figure 4 The dotted arrows indicate the stretching direction. In this example, stretching means stretching in the longitudinal direction (the horizontal direction X1 in this example).

[0071] When the first piezoelectric film 41 and the second piezoelectric film 42 are stretched in the left-right direction X1, the surface of the first piezoelectric film 41 and the second piezoelectric film 42 that generates a positive potential is defined as the front surface, and the opposite side is defined as the back surface. The front surfaces or back surfaces of the first piezoelectric film 41 and the second piezoelectric film 42 are connected, for example, using a conductive tape adhered to both sides. In this example, the second electrode portion P12 of the first piezoelectric film 41 and the first electrode portion P21 of the second piezoelectric film 42 are connected. Furthermore, the second electrode portion P12 and the second electrode 21 are grounded, for example.

[0072] In this example, when the first piezoelectric film 41 is stretched in the left-right direction X1, a positive potential is generated at the first electrode portion P11 relative to the second electrode portion P12. Furthermore, when the second piezoelectric film 42 is stretched in the left-right direction X1, a positive potential is generated at the second electrode portion P22 relative to the first electrode portion P21.

[0073] The difference in potential between the first electrode portion P11 and the second electrode portion P12 is referred to as a first potential difference V1 , and the difference in potential between the first electrode portion P21 and the second electrode portion P22 is referred to as a second potential difference V2 .

[0074] When the first piezoelectric film 41 and the second piezoelectric film 42 are extended in the left-right direction X1 by the same force, the first potential difference V1 and the second potential difference V2 have the same magnitude.

[0075] A calculation circuit (not shown) connected to the piezoelectric film 4 outputs an output value based on the sum of the first potential difference V1 and the second potential difference V2.

[0076] On the other hand, for example, Figure 5 As shown, there is a case where the piezoelectric film 4 is bent in the up-down direction Y1 by a force in the vertical direction.

[0077] When the first piezoelectric film 41 and the second piezoelectric film 42 are bent by a force in the vertical direction (vertical direction Y1), it is assumed that the median line of stress is located between the first piezoelectric film 41 and the second piezoelectric film 42. In this case, the first piezoelectric film 41 stretches in the longitudinal direction (lateral direction X1). On the other hand, the second piezoelectric film 42 contracts in the longitudinal direction (lateral direction X1). In addition, Figure 5 The dashed arrows shown indicate the stretching direction of the first piezoelectric film 41. Figure 5 The dashed-dotted arrows shown indicate the contraction direction of the second piezoelectric film 42 .

[0078] In the first piezoelectric film 41, a positive potential (+V1) is generated at the first electrode portion P11 relative to the second electrode portion P12. Furthermore, the first piezoelectric film 41 and the second piezoelectric film 42 are connected so that their back surfaces are in contact with each other when stretched in the left-right direction X1. Therefore, when bent in the vertical direction, a negative potential (-V2) is generated at the second electrode portion P22 relative to the first electrode portion P21 of the second piezoelectric film 42.

[0079] When the piezoelectric film 4 bends due to a force in the vertical direction, if the absolute value of the first potential difference V1 and the absolute value of the second potential difference V2 are the same, the output value from the deformation detection circuit is zero or a value close to zero.

[0080] Therefore, the deformation detection sensor 10 outputs a high output value for expansion and contraction deformation in the horizontal direction (including the longitudinal direction), and outputs an output value of zero or close to zero for bending deformation in the vertical direction.

[0081] [Deformation Detection Sensor Operation]

[0082] Reference Figure 6 、 Figure 7 as well as Figure 8 , deformation of the piezoelectric film 4 caused by pressure applied to the touch panel 1 will be described. Figure 6 It is a cross-sectional view showing an example of a depressed position of the touch panel 1 as viewed from the front-back direction Z1. Figure 7 This is a cross-sectional view showing an example of deformation of the deformation detecting portion when point A is pressed downward. Figure 8 This is a cross-sectional view showing an example of deformation of the deformation detecting portion when point B is pressed downward.

[0083] When the touch panel 1 is pressed by the user (in this case, the force acting in the horizontal direction is Pd1 and the force acting in the vertical direction is Pd2 (see Figure 6 )), a vertical force Pd1 and a horizontal force Pd2 act on the beam 33. In this example, the deformation of the beam 33 caused by the vertical force Pd1 is described in detail. When the touch panel 1 is pressed by the user, the beam 33 is elastically deformed by the vertical force. Figure 7 and Figure 8 As shown, the second portion 32 of the retaining portion 3 is displaced in the oblique directions (horizontally and vertically). In this case, the piezoelectric film 4 is deformed by the horizontal force Pd1 so as to be stretched in the horizontal direction (left-right direction X1). In other words, the piezoelectric film 4 is stretched in the left-right direction X1 by the horizontal force Pd1. In addition, the piezoelectric film 4 is bent in the vertical direction by the vertical force Pd2. In this case, the piezoelectric film 4 is connected to the portion 31A of the first portion 31 at the first connection position 43 and to the second portion 32 at the second connection position 44, and thus bends with the first connection position 43 as a fulcrum.

[0084] A case where the user presses point A and point B on the touch panel 1 will be described.

[0085] like Figure 6 As shown, point A is on the left side of the touch panel 1 in the left-right direction X1. Furthermore, point B is on the right side of the touch panel 1 in the left-right direction X1. That is, point A is farther from the second connection point 44 where the piezoelectric film 4 is connected to the holder 3 than point B is from the second connection point 44 where the piezoelectric film 4 is connected to the holder 3. Furthermore, the user applies the same force when pressing points A and B on the touch panel 1.

[0086] If the force applied by the user is the same, the amount of horizontal elongation and deformation will be the same whether the user is pressing at point A or point B. Figure 7 and Figure 8 As shown, even if the user presses points A and B with the same force, the amount of deformation of the piezoelectric film 4 in the vertical direction is different when point A is pressed and when point B is pressed.

[0087] When point B is pressed, the vertical force Pd2 has a greater influence on the bending deformation of the piezoelectric film 4 than when point A is pressed. If the user presses points A and B of the touch panel 1 with the same force, the vertical bending deformation of the piezoelectric film 4 is greater when point B is pressed.

[0088] When the touch panel 1 is viewed from above, the closer the pressed position is to the fulcrum serving as the first connection point 43, the greater the amount of deformation in the vertical direction of the piezoelectric film 4. Thus, the amount of deformation in the piezoelectric film 4 caused by pressure applied to the touch panel 1 varies depending on the position of pressure applied when the touch panel 1 is viewed from above.

[0089] [Function and Effect]

[0090] The amount of pressure applied to the touch panel 1 corresponds to the amount of deformation caused by the elongation and bending of the piezoelectric film 4 and is detected using the output value (first potential difference V1 + second potential difference V2). In this embodiment, the first potential difference V1 and the second potential difference V2 corresponding to changes in the vertical direction have opposite polarities and cancel each other out. Therefore, the deformation detection sensor 10 outputs no or almost no output value due to bending in the vertical direction.

[0091] Reference Figure 9 and Figure 10 The following describes a comparison of the output values ​​of the piezoelectric film 4 of this embodiment and the output values ​​of the piezoelectric film of the reference example. The reference example herein refers to a piezoelectric film that does not have the characteristics of the present invention. Specifically, the piezoelectric film of the reference example does not have two piezoelectric films that generate different charges and, as a result, opposite potentials when bent in the stacking direction. Figure 9 4 is a reference diagram showing an example of the output value of the piezoelectric film 4 . Figure 9 The horizontal axis shown represents time. Figure 9 The vertical axis shown represents the output value of the piezoelectric film 4 . Figure 10 : is a reference diagram showing an example of output values ​​of a piezoelectric film of a reference example.

[0092] Figure 10 The horizontal axis shown represents time. Figure 10 The vertical axis is the output value of the piezoelectric film. Figure 9 and Figure 10 The dashed lines Oa1 and Oa2 shown represent the output value at point A, and the solid lines Ob1 and Ob2 represent the output value at point B.

[0093] like Figure 9 As shown in FIG. 1 , the output values ​​from the piezoelectric film 4 are substantially the same at points A and B. That is, the output value of the piezoelectric film 4 of this embodiment is hardly affected by the bending in the vertical direction. On the other hand, in the piezoelectric film of the reference example, as shown in FIG. Figure 10 As shown, the output values ​​at points A and B differ significantly. When point B is pressed, the output value of the piezoelectric film of the reference example detects not only the amount of elongation caused by the horizontal force but also the amount of bending caused by the vertical force. In other words, the output value of the piezoelectric film of the reference example is influenced by the bending caused by the vertical force, depending on the position at which the touch panel 1 is pressed.

[0094] The deformation detection sensor 10 of Embodiment 1 includes a first piezoelectric film 41 and a second piezoelectric film 42 that generate different charges and, as a result, opposite potentials when bent in the stacking direction. This reduces the effects of vertical forces acting on the piezoelectric film 4. Specifically, the deformation detection sensor 10 can detect only horizontal deformation across the entire surface of the touch panel 1, regardless of the location of the pressure applied. The output value of the deformation detection sensor 10 remains constant regardless of where the touch panel 1 is pressed. Therefore, the deformation detection sensor 10 of one embodiment of the present invention can output a uniform output value even when the touch panel 1 is pressed at different locations, provided the amount of pressure remains uniform.

[0095] [Variation of Embodiment 1]

[0096] The structure of the piezoelectric film 4 will be described below in a configuration other than the above-described embodiment 1. In a modified example of embodiment 1, the film length of the first piezoelectric film 41 and the film length of the second piezoelectric film 42 in the left-right direction X1 are the same, and the film width of the first piezoelectric film 41 and the film width of the second piezoelectric film 42 in the front-back direction Z1 are the same.

[0097] When the first piezoelectric film 41 expands in the left-right direction X1 and the second piezoelectric film 42 contracts in the left-right direction X1, the conditions for making the first potential difference V1 and the second potential difference V2 equal are described using the following equations [Equation 1] to [Equation 3].

[0098] In addition, the stress generated in the piezoelectric film is set to σ, the strain generated in the piezoelectric film is set to s, the Young's modulus of the piezoelectric film is set to Y, the electric field generated in the piezoelectric film is set to E, the potential difference (voltage) between the first main surface and the second main surface of the piezoelectric film is set to V, the piezoelectric constant of the piezoelectric film is set to d31, the bending deformation amount of the piezoelectric film in the left-right direction X1 is set to Δ, the film length of the piezoelectric film in the left-right direction X1 is set to L, the dielectric constant of the piezoelectric film is set to ε, and the thickness of the piezoelectric film is set to ts.

[0099] The stress σ is obtained by the following [Formula 1].

[0100] [Formula 1]

[0101] σ=Y×s=Y×Δ / L

[0102] The electric field E is obtained by the following [Formula 2].

[0103] [Formula 2]

[0104] E=d31 / ε×σ=d31 / ε×Y×Δ / L

[0105] The potential difference (voltage) V is obtained by the following [Formula 3].

[0106] [Formula 3]

[0107] V=t×E=t / ε×Δ / L×d31×Y

[0108] If the thickness of the first piezoelectric film 41 is set to ts1, the thickness of the second piezoelectric film 42 is set to ts2, the dielectric constant of the first piezoelectric film is set to ε1, and the dielectric constant of the second piezoelectric film is set to ε2, then the first ratio ts1 / ε1, which is the ratio of the thickness ts1 of the first piezoelectric film 41 to the dielectric constant ε1 of the first piezoelectric film 41, and the second ratio ts2 / ε2, which is the ratio of the thickness ts2 of the second piezoelectric film 42 to the dielectric constant ε2 of the second piezoelectric film 42, are the same (ts1 / ε1=ts2 / ε2). If the piezoelectric constant of the first piezoelectric film 41 and the piezoelectric constant of the second piezoelectric film 42 are the same d31, then the first potential difference V1 and the second potential difference V2 generated by the first piezoelectric film 41 and the second piezoelectric film 42, respectively, are equal.

[0109] In addition, according to [Formula 3], in addition to the above, if the product of the piezoelectric constant (d311) of the first piezoelectric film and the thickness ts1 of the first piezoelectric film 41 (d311)×ts1 and the product of the piezoelectric constant (d312) of the second piezoelectric film 42 and the thickness ts2 of the second piezoelectric film 42 (d312)×ts2 are the same (d311×ts1=d312×ts2), the dielectric constant ε1 of the first piezoelectric film 41 and the dielectric constant ε2 of the second piezoelectric film 42 are the same, then the first potential difference V1 and the second potential difference V2 generated by the first piezoelectric film 41 and the second piezoelectric film 42 respectively are equal.

[0110] [Implementation Method 2]

[0111] Reference Figure 11 、 Figure 12 、 Figure 13 、 Figure 14 as well as Figure 15 , a deformation detection sensor 10A according to a second embodiment will be described. Figure 11 This is an exploded perspective view of an electronic device 100A including the deformation detection sensor 10A according to the second embodiment. Figure 12 This is a side view of the piezoelectric film 4A as viewed from the front-back direction Z1 in the second embodiment. Figure 13 It is a bottom view of the deformation detection sensor 10A according to the second embodiment. Figure 14 yes Figure 13 Cross-sectional view at line BB. Figure 15 4 is a reference diagram showing output values ​​of the piezoelectric film 4A when point A is pressed and when point B is pressed. Figure 15 The horizontal axis represents the distance from the second connection position 44. Figure 15The vertical axis represents the output value of the deformation detection sensor 10A. In addition, the same reference numerals are attached to the same configurations as those in the first embodiment, and detailed description thereof will be omitted.

[0112] In this example, the displacement amount of the second portion 32 of the holding portion 3A caused by pressing against the touch panel 1 is controlled.

[0113] In addition, in this example, Figure 11 As shown, the deformation detection sensor 10A includes a piezoelectric film 4A. Figure 11 and Figure 12 As shown in FIG. 1 , the piezoelectric film 4A has a film shape that is vertically elongated in the left-right direction X1. Figure 12 As shown, the piezoelectric film 4A has a first electrode portion P31 on its upper surface and a second electrode portion P32 on its lower surface. Furthermore, the piezoelectric film 4A includes a piezoelectric body between the electrode portions. The piezoelectric film 4A is connected to a calculation circuit (not shown). In this example, the piezoelectric film 4A is constructed from a single film. Alternatively, the piezoelectric film 4A may be constructed from a single film or a plurality of films stacked together.

[0114] When the touch panel 1 is pressed, the piezoelectric film 4A expands horizontally (e.g., the horizontal direction X1). Furthermore, when the touch panel 1 is pressed, the piezoelectric film 4A bends vertically (the vertical direction Y1). A calculation circuit (not shown) calculates a potential difference based on the output value from the piezoelectric film 4A.

[0115] like Figure 13 As shown, the holding portion 3A includes a plurality of ( Figure 13 Two) first beams 33A and a plurality of (in Figure 13 There are two second beam portions 33B.

[0116] [Structure of the holding portion]

[0117] The plurality of first beams 33A are provided at positions close to the second connection location 44 along the left-right direction X1. Furthermore, the plurality of second beams 33B are provided at positions farther from the second connection location 44 than the first beams 33A. Furthermore, a single first beam 33A or a single second beam 33B may be provided.

[0118] In this example, when the normal direction (vertical direction Y1 ) of the upper surface (connecting surface) of the holding portion 3 is defined as the thickness direction, the first beam portion 33A is less likely to deform in the thickness direction than the second beam portion 33B.

[0119] Hereinafter, the structures of the first beam portion 33A and the second beam portion 33B will be described in more detail.

[0120] like Figure 14 As shown, the plurality of first beams 33A have a rectangular shape when viewed from above. Similarly, the plurality of second beams 33B have a rectangular shape when viewed from above. In this example, the first thickness tf1, which is the length of the first beam 33A in the vertical direction Y1, and the second thickness tf2, which is the length of the second beam 33B in the vertical direction Y1, are the same. Furthermore, the first thickness tf1 and the second thickness tf2 are preferably between 0.3 mm and 10 mm.

[0121] In addition, if Figure 13 As shown, the first length L1, which is the length of the first beam portion 33A in the front-back direction Z1, and the second length L2, which is the length of the second beam portion 33B in the front-back direction Z1, are the same. Preferably, the first length L1 and the second length L2 are 5 mm to 30 mm.

[0122] The first width W1 of the first beam portion 33A in the left-right direction X1 is longer than the second width W2 of the second beam portion 33B in the left-right direction X1. Preferably, the first width W1 of the first beam portion 33A and the second width W2 of the second beam portion 33B are 0.5 mm to 2 mm.

[0123] Since the first width W1 is longer than the second width W2, the first beam portion 33A is less likely to bend in the vertical direction Y1 than the second beam portion 33B. Furthermore, the second beam portion 33B, which has a second width W2 shorter than the first width W1, is more likely to bend in the vertical direction Y1 than the first beam portion 33A.

[0124] Here, assuming that the output value of the piezoelectric film 4A when the point B is pressed is “1”, the output value of the piezoelectric film 4A when the point A is pressed will be described. Figure 15 The straight line Cp1 shown represents the inclination when the ratio of the first width W1 of the first beam portion 33A to the second width W2 of the second beam portion 33B is “1” to “1”. Figure 15 The straight line Cp2 shown represents the inclination when the ratio of the first width W1 of the first beam portion 33A to the second width W2 of the second beam portion 33B is “2” to “1”. Figure 15 The straight line Cp3 shown in FIG. 1 represents the inclination when the ratio of the first width W1 of the first beam portion 33A to the second width W2 of the second beam portion 33B is "3" to "1". Figure 15 In FIG, the force applied to the touch panel 1 at point A and point B is the same.

[0125] Furthermore, when comparing the inclinations of straight lines Cp1, Cp2, and Cp3, straight line Cp1 has the largest inclination. On the other hand, straight line Cp3 has the smallest inclination. Specifically, when the ratio of first width W1 to second width W2 is 1:1, the difference in the amount of deformation of the piezoelectric film 4A compared to the case where point B is pressed increases as the pressed position moves away from the second connection position 44.

[0126] In addition, in the straight line Cp1, as Figure 15 As shown, the output value of the piezoelectric film 4A, which is a relative value when point A is pressed, is the smallest compared to the straight line Cp2 and the straight line Cp3.

[0127] On the other hand, along line Cp3, the output value of the piezoelectric film 4A when point A is pressed is closest to "1" compared to lines Cp1 and Cp2. Thus, if the ratio of the first width W1 to the second width W2 is "3" to "1," it can be assumed that there is no actual difference in the amount of deformation of the piezoelectric film 4A when point A is pressed and when point B is pressed.

[0128] [Function and Effect]

[0129] When the touch panel 1 is pressed at point B, the piezoelectric film 4A is less likely to deform in the vertical direction Y1 than when the touch panel 1 is pressed at point A. Furthermore, when point A is pressed, the piezoelectric film 4A is more likely to deform in the vertical direction Y1 than when point B is pressed.

[0130] For example, if the first width W1 of the first beam portion 33A is approximately three times the second width W2 of the second beam portion 33B, the amount of deformation of the piezoelectric film in the vertical direction Y1 when point A is pressed is the same. In other words, if the first width W1 of the first beam portion 33A is approximately three times the second width W2 of the second beam portion 33B, the output value of the piezoelectric film 4A is the same as the output value of the piezoelectric film 4A when point B is pressed.

[0131] By making the first width W1 larger than the second width W2, the influence of the force acting in the vertical direction on the piezoelectric film 4A can be reduced. Therefore, the deformation detection sensor 10A of the second embodiment can output a uniform output value even when the touch panel 1 is pressed at different positions, as long as the amount of pressure is uniform.

[0132] [Definition of bending ease based on the second moment of section]

[0133] Reference Figure 16 and Figure 17 , the bending ease based on the second moment of section is explained. Figure 16 and Figure 17Taking the member 6 shown as an example, the degree of bending ease based on the second moment of area will be described. Figure 16 This is a side view of a member showing an example of the deflection of the member used in the following description. Figure 16 It is a side view of component 6. Figure 16 The indicated L represents the length of the member 6 in the longitudinal direction of the member 6 . Figure 16 The P shown represents the force applied in the vertical direction to the component 6. Figure 17 The direction of the force P is shown by an arrow. Figure 16 The indicated delta represents the magnitude of the deflection of the component 6 . Figure 17 yes Figure 16 Cross-sectional view at line CC. Figure 17 The h shown represents the length (thickness) of the member 6 in the direction in which the member 6 is bent by the force P. Figure 17 The indicated b represents the length (width) of the member 6 in a direction perpendicular to the direction in which the force P is applied.

[0134] like Figure 16 As shown, component 6 is one end (at Figure 16 In addition, for example, Figure 17 As shown, the cross section of the component 6 has a rectangular shape.

[0135] The other end (free end) of the member 6 (at Figure 16 (right end in the center) deflects downward when a vertical force P is applied. Component 6 has a rectangular cross-section consisting of width b and thickness h. The second moment of area l of component 6 is calculated using the following [Equation 4].

[0136] [Formula 4]

[0137] l=bh 3 / 12

[0138] The deflection δ of the member 6 when a vertical force P is applied is calculated by the following [Formula 5]. In addition, the longitudinal elastic modulus (Young's modulus) of the member 6 is represented by Y.

[0139] [Formula 5]

[0140] δ=(PL 3 ) / 3Yl

[0141] When the member 6 is assumed to be an elastic body, the force P applied to the member 6 can be calculated as shown in the following [Formula 6] by setting the spring constant of the member 6 as the elastic body to K.

[0142] [Formula 6]

[0143] P=K×δ

[0144] When [Formula 5] is substituted into δ of [Formula 6] and [Formula 4] is substituted into the area second moment l, the spring constant can be expressed as in the following [Formula 7].

[0145] [Formula 7]

[0146] K=3Yl / L 3 ∝(3Y×bh 3 ) / (12L 3 )∝bh 3 / L 3

[0147] In the present embodiment, the spring constant K shown in [Formula 7] is defined as the degree of easiness of bending of the member 6 .

[0148] The bending ease K1 of the first beam portion 33A in the vertical direction (vertical direction Y1) is calculated using the above-mentioned [Formula 7]. In this case, when the vertical force is set to force P, Figure 17 The thickness h shown corresponds to the first thickness tf1 of the first beam portion 33A. Figure 17 The width b shown corresponds to the first width W1 of the first beam portion 33A. Figure 16 The indicated L corresponds to the first length L1 of the first beam portion 33A.

[0149] Therefore, the bending ease K1 of the first beam portion 33A in the vertical direction is expressed by the following [Formula 8].

[0150] [Formula 8]

[0151] K1=(W1×(tf1) 3 ) / (L1) 3 =(tf1) 3 (W1) / (L1) 3

[0152] Furthermore, the bending ease K2 of the second beam portion 33B in the vertical direction (the up-down direction Y1 ) is expressed by the following [Formula 9].

[0153] [Formula 9]

[0154] K2=(W2×(tf2) 3 ) / (L2) 3 =(tf2) 3 (W2) / (L2) 3

[0155] Assuming that the first length L1 and the second length L2 are the same, and the first thickness tf1 and the second thickness tf2 are the same, in this case, according to the above equation, the ratio (K1:K2) between the bendability K1 of the first beam portion 33A and the bendability K2 of the second beam portion 33B caused by the vertical force P is the ratio (W1:W2) between the first width W1 and the second width W2. Therefore, the ratio between the bendability K1 of the first beam portion 33A and the bendability K2 of the second beam portion 33B caused by the vertical force P can be controlled using the first width W1 and the second width W2.

[0156] [Variation of Embodiment 2]

[0157] A description will be given of the structure of a modified example of the above-mentioned embodiment 2. In this example, the first width W1, the second width W2, the first length L1, and the second length L2 are calculated when the first length L1 and the second length L2 are different.

[0158] In addition, in this example, the following conditions are assumed. The first beam portion 33A and the second beam portion 33B are formed of the same material. The first thickness tf1, which is the length of the first beam portion 33A in the vertical direction Y1 (thickness direction), and the second thickness tf2, which is the length of the second beam portion 33B in the vertical direction Y1, are the same (see Figure 14 The bending ease of the first beam portion 33A in the horizontal direction (left-right direction X1) and the bending ease of the second beam portion 33B in the horizontal direction (left-right direction X1) are the same as K.

[0159] By using the above [Formula 7], the vertical force Pd2 (refer to Figure 6 ) the bending ease K1 of the first beam portion 33A and the bending ease K2 of the second beam portion 33B.

[0160] Regarding the first beam portion 33A, when the force Pd1 in the left-right direction X1 is set to Figure 17 In the case of the force P shown, Figure 17 The thickness h shown corresponds to the first width W1 of the first beam portion 33A. Figure 17 The width b shown corresponds to the first thickness tf1 of the first beam portion 33A. Figure 17 In the case of the force P shown, Figure 17 The thickness h shown corresponds to the second width W2 of the second beam portion 33B. Figure 17 The width b shown corresponds to the second thickness tf2 of the second beam portion 33B.

[0161] The bending ease K of the first beam portion 33A and the second beam portion 33B in the left-right direction X1 is expressed as the following [Equation 10] based on Equation 7.

[0162] [Equation 10]

[0163] ((W1) 3 ×tf1) / (L1) 3 =((W2) 3 ×tf2) / (L2) 3 =K

[0164] When [Equation 10] is used as a constraint condition, the bending ease K1 of the first beam portion 33A in the vertical direction is calculated as follows.

[0165] K1=(W1×(tf1) 3 ) / (L1) 3 =K(tf1) 2 / (W1) 2

[0166] In addition, when [Equation 10] is used as a constraint condition, the bending ease K2 of the second beam portion 33B in the vertical direction is calculated as follows.

[0167] K2=(W2×(tf2) 3 ) / (L2) 3 =K(tf2) 2 / (W2) 2

[0168] The ratio of the bending ease K1 of the first beam portion 33A in the vertical direction to the bending ease K2 of the second beam portion 33B in the vertical direction is represented by U. In this case, (W2 / W1) 2 To control the bending ease ratio U. And, for the determined (W2 / W1) 2 The first length L1 and the second length L2 are selected so as to satisfy [Formula 10].

[0169] For example, the first beam portion 33A and the second beam portion 33B may be formed so that the first length L1 is longer than the second length L2.

[0170] Therefore, it is believed that the amount of vertical deformation of the piezoelectric film 4A does not differ in actual use regardless of the position at which the touch panel 1 is pressed. Therefore, in the deformation detection sensor 10A, the influence of the force acting in the vertical direction on the piezoelectric film 4A can be reduced regardless of the position at which the touch panel 1 is pressed when viewed from above.

[0171] Finally, the description of the various embodiments described above should be considered in all respects to be illustrative and non-restrictive. The scope of the present invention is not indicated by the above-described embodiments but by the claims. Furthermore, it is intended that the scope of the present invention encompass all modifications that come within the meaning and scope of the claims.

[0172] Alternatively, the metal plate forming the frame 2 may be coated with a resin such as polyimide. Furthermore, the frame 2 may be formed of a material other than a metal plate (eg, acrylic resin, PET, polycarbonate, glass epoxy, FRP, metal, or glass).

[0173] Alternatively, the metal plate forming the holding portion 3 or 3A may be coated with a resin such as polyimide. Alternatively, the holding portion 3 or 3A may be formed of a material other than a metal plate (e.g., acrylic resin, PET, polycarbonate, glass epoxy, FRP, metal, or glass).

[0174] The first portion 31 , the second portion 32 , and the plurality of beams 33 may not be formed of a single member. The first portion 31 , the second portion 32 , the first beam 33A, and the second beam 33B may not be formed of a single member.

[0175] The electrode on the bottom surface of the first piezoelectric film 41 and the electrode on the top surface of the second piezoelectric film 42 may not be at the ground potential (reference potential). In this case, the electrode on the top surface of the first piezoelectric film 41 and the electrode on the bottom surface of the second piezoelectric film 42 may be at the ground potential.

[0176] The thickness ts1 of the first piezoelectric film 41 and the thickness ts2 of the second piezoelectric film 42 may be different. For example, the dielectric constant of the first piezoelectric film 41 is set to dielectric constant ε1, the piezoelectric constant of the first piezoelectric film 41 is set to piezoelectric constant d311, and the thickness of the first piezoelectric film 41 is set to thickness ts1. Alternatively, for example, the dielectric constant of the second piezoelectric film 42 is set to ε2, the piezoelectric constant of the second piezoelectric film 42 is set to d312, and the thickness of the second piezoelectric film 42 is set to ts2. In this case, the following equations [Equation 11] and [Equation 12] hold true.

[0177] [Equation 11]

[0178] ts1×ε2=ts2×ε1

[0179] [Equation 12]

[0180] ts1×d311=ts2×d312

[0181] ts1 and ts2 are selected so as to satisfy [Formula 11] and [Formula 12]. In this case, different values ​​may be selected for ts1 and ts2.

[0182] Description of Reference Numerals

[0183] 1. Touch panel (operation panel); 2. Frame; 3. 3A. Holding portion; 4. 4A. Piezoelectric film; 5. Actuator; 10. 10A. Deformation detection sensor; 31. First part; 32. Second part; 33. Beam; 33A. First beam; 33B. Second beam; 41. First piezoelectric film; 42. Second piezoelectric film; 43. First connection position; 44. Second connection position; d31. Piezoelectric constant; L1. First length; L2. Second length; tf1. First thickness; tf2. Second thickness; ts1. Thickness of the first piezoelectric film; ts2. Thickness of the second piezoelectric film; W1. First width; W2. Second width; X1. Left-right direction (first direction); Y1. Up-down direction (second direction); ε. Dielectric constant.

Claims

1. A deformation detection sensor, characterized in that: The deformation detection sensor comprises: A holding portion connected to the operation panel receiving a push operation by a user and holding the operation panel; and a piezoelectric film connected to the holding portion and detecting deformation of the holding portion; The holding portion has: Part 1, which is connected to the frame; Part 2, which is connected to the operation panel; and The beam portion connects the first portion and the second portion and has elasticity. The piezoelectric film is connected across the first portion and the second portion, The piezoelectric film includes a first piezoelectric film and a second piezoelectric film stacked on each other. The first piezoelectric film and the second piezoelectric film are polarized to the same potential with polarities different from each other when bent in the stacking direction.

2. The deformation detection sensor according to claim 1, characterized in that: The first piezoelectric film and the second piezoelectric film have the same shape and the same size in a plan view.

3. The deformation detection sensor according to claim 2, characterized in that: The length of the first piezoelectric film in the stacking direction is set to the thickness of the first piezoelectric film. The length of the second piezoelectric film in the stacking direction is set to the thickness of the second piezoelectric film. A first ratio, which is a ratio of the thickness of the first piezoelectric film to the dielectric constant of the first piezoelectric film, and a second ratio, which is a ratio of the thickness of the second piezoelectric film to the dielectric constant of the second piezoelectric film, are the same.

4. The deformation detection sensor according to any one of claims 1 to 3, characterized in that: The piezoelectric constant of the first piezoelectric film is the same as the piezoelectric constant of the second piezoelectric film.

5. The deformation detection sensor according to any one of claims 1 to 3, characterized in that: The product of the piezoelectric constant of the first piezoelectric film and the thickness of the first piezoelectric film and the product of the piezoelectric constant of the second piezoelectric film and the thickness of the second piezoelectric film are the same.

6. A deformation detection sensor, characterized in that: The deformation detection sensor comprises: A holding portion connected to the operation panel receiving a push operation by a user and holding the operation panel; and a piezoelectric film connected to the holding portion and detecting deformation of the holding portion; The holding portion has: Part 1, which is connected to the frame; Part 2, which is connected to the operation panel; and A plurality of beams connecting the first portion and the second portion and having elasticity, The piezoelectric film is connected across the first portion and the second portion, A direction from a first connection position where the first portion is connected to the piezoelectric film toward a second connection position where the second portion is connected to the piezoelectric film is defined as a first direction. The plurality of beam portions include: a first beam portion provided at a position close to the second connection position along the first direction; and a second beam portion provided at a position farther from the second connection position than the distance between the first beam portion and the second connection position. When the normal direction of the connection surface of the holding portion connected to the operation panel is set as the thickness direction, the first beam portion is less likely to deform in the thickness direction than the second beam portion.

7. The deformation detection sensor according to claim 6, characterized in that: A first thickness, which is the length of the first beam portion in the thickness direction, and a second thickness, which is the length of the second beam portion in the thickness direction, are the same. A direction parallel to the connection surface and perpendicular to the first direction is defined as a second direction, The length of the first beam portion in the second direction is the same as the length of the second beam portion in the second direction. When the length of the first beam portion in the first direction is defined as the first width of the first beam portion and the length of the second beam portion in the first direction is defined as the second width of the second beam portion, The first width is greater than the second width.

8. The deformation detection sensor according to claim 6, characterized in that: A first thickness, which is the length of the first beam portion in the thickness direction, and a second thickness, which is the length of the second beam portion in the thickness direction, are the same. A direction parallel to the connection surface and perpendicular to the first direction is defined as a second direction, The length of the first beam portion in the second direction is different from the length of the second beam portion in the second direction. When the length of the first beam portion in the first direction is defined as the first width of the first beam portion and the length of the second beam portion in the first direction is defined as the second width of the second beam portion, Satisfies the following formula 1, Formula 1: (W1 3 ×t) / L1 3 =(W2 3 ×t) / L2 3 .

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