WO2020129346A1 - Pressure sensor and pressure detection device - Google Patents

Pressure sensor and pressure detection device Download PDF

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Publication number
WO2020129346A1
WO2020129346A1 PCT/JP2019/037944 JP2019037944W WO2020129346A1 WO 2020129346 A1 WO2020129346 A1 WO 2020129346A1 JP 2019037944 W JP2019037944 W JP 2019037944W WO 2020129346 A1 WO2020129346 A1 WO 2020129346A1
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WO
WIPO (PCT)
Prior art keywords
pressure sensor
elastic modulus
joining member
piezoelectric film
gpa
Prior art date
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PCT/JP2019/037944
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French (fr)
Japanese (ja)
Inventor
真吾 原田
尚志 木原
林　信行
宮本　昌幸
Original Assignee
株式会社村田製作所
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Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Priority to CN201990000294.4U priority Critical patent/CN213120923U/en
Publication of WO2020129346A1 publication Critical patent/WO2020129346A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/022—Mechanical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/025—Electric or magnetic properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/88—Mounts; Supports; Enclosures; Casings

Definitions

  • the present invention relates to a pressure sensor for detecting pressure and a pressure detection device using the pressure sensor.
  • Patent Document 1 discloses a pressure sensor in which a piezoelectric film is attached to a substrate.
  • the pressure sensor of Patent Document 1 detects pressure on the touch panel by attaching the pressure sensor to the touch panel with an adhesive.
  • the elastic modulus of the adhesive changes with changes in temperature.
  • the output of the pressure sensor changes.
  • the output of the pressure sensor may change twice or more between low temperature and normal temperature.
  • an object of the present invention is to provide a pressure sensor and a pressure detection device capable of suppressing a change in output even if the elastic modulus of the adhesive changes due to a temperature change.
  • a pressure sensor includes a reinforcing material, a joining member, and a sensor body bonded to the reinforcing material via the joining member.
  • the elastic modulus of the reinforcing material is 50 GPa or more, and the elastic modulus of the joining member is 0.1 GPa or more. Even if it is attached to the housing of a touch panel or a smartphone that is deformed or distorted by pressing with a pressure sensitive adhesive, the neutral surface of the distortion will be present inside the reinforcing material due to the hard reinforcing material and the joining member. The output change of the sensor with respect to temperature is suppressed.
  • the pressure sensor can suppress changes in output even if the elastic modulus of the adhesive changes due to temperature changes.
  • FIG. 1A is a perspective view of the electronic device 101
  • FIG. 1B is a sectional view.
  • 3 is a cross-sectional view of the pressure sensor 20.
  • FIG. It is a top view of the piezoelectric film 27.
  • FIGS. 4A and 4B are cross-sectional views of the pressure sensor in the case where the reinforcing material 21 and the joining member 22 are not provided.
  • 5A and 5B are cross-sectional views of the pressure sensor 20 of this embodiment.
  • FIG. 6A to FIG. 6D are diagrams showing the relationship between the distance from the upper surface (starting point) of the adhesive and the strain.
  • FIG. 7(A) is a diagram showing the relationship between the elastic modulus of the reinforcing material and the fluctuation rate of the output, and FIG.
  • FIG. 7(B) shows the elasticity of the joining member 22 when the elastic modulus of the reinforcing material 21 is 50 GPa. It is a figure which shows the relationship between a rate and an output fluctuation rate. As a reference example, it is a diagram showing the relationship between the load and the output voltage generated in the pressure sensor when the reinforcing member 21 and the joining member 22 are not provided. It is a figure which shows the relationship between the weight produced in the pressure sensor 20 of this embodiment, and an output voltage.
  • FIG. 10A is a perspective view of the pressure sensor 30 according to the first embodiment
  • FIG. 10B is an exploded perspective view.
  • 11A to 11D are views showing the holding and measuring mechanism 61 of the pressure sensor 30 according to the first embodiment.
  • FIG. 6 is a flowchart of a measuring method using the holding and measuring mechanism 61 of the pressure sensor 30 according to the first embodiment.
  • 13A and 13B are cross-sectional views showing an example of a conventional holding and measuring mechanism 131 of the pressure sensor 30 as a reference example.
  • 14A and 14B are views showing the holding and measuring mechanism 62 of the pressure sensor 50 according to the second embodiment.
  • 15(A) and 15(B) are views showing the holding and measuring mechanism 63 of the pressure sensor 50 according to the third embodiment.
  • FIG. 16A is a graph showing the variation in the measured values of Example 2 and the comparative example
  • FIG. 16B is a graph showing the variation of the measured values in Example 3 and the comparative example.
  • 17(A) and 17(B) are diagrams showing the holding and measuring mechanism 64 of the pressure sensor 60 according to the fourth embodiment.
  • FIG. 1A is a perspective view of the electronic device 101.
  • FIG. 1B is a cross-sectional view taken along the line II of FIG.
  • the width direction (horizontal direction) of the housing 102 is the X direction
  • the length direction (longitudinal direction) is the Y direction
  • the thickness direction is the Z direction.
  • the electronic device 101 is an example of the pressure detection device of the present invention.
  • the electronic device 101 includes a casing 102 having a substantially rectangular parallelepiped shape whose upper surface is opened.
  • the electronic device 101 includes a flat surface panel 103 arranged so as to seal the opening on the upper surface of the housing 102.
  • the front panel 103 functions as an operation surface on which a user performs a touch operation using a finger or a pen.
  • the electronic device 101 includes a display unit 104, a pressure sensor 20, and a circuit board 111 inside a housing 102.
  • the first main surface (upper surface) of the display unit 104 is attached to the second main surface (lower surface) of the front panel 103.
  • the pressure sensor 20 is attached to the second main surface (lower surface) of the display unit 104.
  • FIG. 2 is a sectional view of the pressure sensor 20.
  • the pressure sensor 20 is attached to the display unit 104 with an adhesive 105.
  • the pressure sensor 20 and the display unit 104 may be connected by a member other than an adhesive.
  • the pressure-sensitive adhesive does not require a step such as curing or drying and has good workability.
  • the manufacturer of the electronic device 101 can install the pressure sensor 20 simply by purchasing the pressure sensor 20 and attaching the pressure sensor 20 to the display unit 104 with an adhesive.
  • the pressure sensor 20 includes a reinforcing member 21, a joining member 22, a first electrode 23, a base material 24, a second electrode 25, a first adhesive layer 26, a piezoelectric film 27, a second adhesive layer 28, and a second adhesive layer in order from the upper surface side. 3 electrodes 29 are provided.
  • the sensor body 200 is configured by the first electrode 23, the base material 24, the second electrode 25, the first adhesive layer 26, the piezoelectric film 27, the second adhesive layer 28, and the third electrode 29.
  • the reinforcing material 21 is made of, for example, a metal material (SUS304, copper, cast iron, aluminum, etc.). Alternatively, the reinforcing material 21 may be glass. As described below, the reinforcing material 21 has an elastic modulus of at least 10 GPa or more.
  • the elastic modulus of the above-mentioned SUS304 is 197 GPa, copper is 110 GPa, cast iron is about 152 GPa, aluminum is 69 GPa, and glass is 80 GPa, and each has an elastic modulus of 10 GPa or more.
  • the reinforcing member 21 is a member having the largest moment of inertia of area among the members forming the pressure sensor 20.
  • the joining member 22 has an elastic modulus of at least 0.1 GPa or more.
  • the joining member 22 of the present embodiment is made of a thermoplastic resin adhesive having an elastic modulus of 0.3 GPa.
  • the joining member 22 is preferably made of a material whose elastic modulus changes little with temperature.
  • the joining member 22 is a material in which the elastic modulus changes less with temperature changes than at least the adhesive agent 105.
  • the elastic modulus of the adhesive agent 105 is about 0.1 MPa at room temperature (25° C.) and about 10 MPa at low temperature ( ⁇ 20° C.).
  • the joining member 22 may be solder.
  • the elastic modulus of the solder is 30 GPa.
  • the base material 24 is made of a resin material such as PI (polyimide) or PET (polyethylene terephthalate).
  • the first electrode 23 is formed on the first surface of the base material 24, and the second electrode 25 is formed on the second surface.
  • the first electrode 23 is a shield electrode and has a ground potential.
  • the reinforcing material 21 is a conductive material and the joining member 22 is solder, the first electrode 23 and the reinforcing material 21 are electrically connected. In this case, the reinforcing material 21 also functions as a shield electrode.
  • the upper surface (first main surface) of the piezoelectric film 27 is connected to the second electrode 25 via the first adhesive layer 26.
  • the lower surface (second main surface) of the piezoelectric film 27 is connected to the third electrode 29 via the second adhesive layer 28.
  • the second moment of area of the members of the pressure sensor 20 that are on the lower surface side of the piezoelectric film 27 is smaller than that of the piezoelectric film 27.
  • the second electrode 25 is a detection electrode and is connected to an arithmetic circuit for voltage detection (for example, the circuit board 111 shown in FIG. 1B).
  • the third electrode 29 is a reference electrode. In the present embodiment, the third electrode 29 has a ground potential and functions as a shield electrode.
  • the third electrode 29 is made of, for example, a conductive shield film or a conductive non-woven fabric.
  • the conductive non-woven fabric can be easily attached so as to cover the entire surface of the piezoelectric film 27.
  • the conductive non-woven fabric is also attached to the first electrode 23 or the reinforcing material 21 so that the third electrode 29 becomes the first electrode. It is also possible to improve the shielding property by electrically connecting to 23 or the reinforcing material 21.
  • FIG. 3 is a plan view of the piezoelectric film 27 as viewed from above.
  • the piezoelectric film 27 is made of, for example, a chiral polymer.
  • the chiral polymer of this embodiment is composed of L-type polylactic acid (PLLA) or D-type polylactic acid (PDLA).
  • the main chain of polylactic acid has a helical structure.
  • Polylactic acid has piezoelectricity when it is uniaxially stretched and molecules are oriented.
  • the uniaxially stretched polylactic acid generates a voltage when it expands and contracts along a direction of 45 degrees with respect to the uniaxially stretched direction.
  • polylactic acid produces piezoelectricity by molecular orientation treatment by stretching, it is not necessary to perform poling treatment unlike other polymers such as PVDF or piezoelectric ceramics.
  • the piezoelectricity of polylactic acid which does not belong to the ferroelectric substance, does not appear due to the polarization of ions unlike the ferroelectric substance such as PVDF or PZT, but is derived from the helical structure that is the characteristic structure of the molecule. ..
  • Polylactic acid does not have the pyroelectricity that occurs with other ferroelectric piezoelectric materials. Therefore, polylactic acid is not affected by the temperature or frictional heat of the user's finger.
  • the piezoelectric film 27 is not limited to polylactic acid, and may be a film formed from a ferroelectric material in which ions are polarized, such as PVDF or PZT subjected to poling treatment.
  • the piezoelectric film 27 of the present embodiment is arranged in a direction in which the uniaxial stretching direction 901 forms an angle of 45 degrees with the Y direction and the Z direction.
  • the front panel 103 bends in the Y direction and the X direction. Therefore, the piezoelectric film 27 stretches in the Y direction and the X direction to generate an electric charge. Therefore, when the user presses the front panel 103, the piezoelectric film 27 generates an electric charge.
  • the amount of electric charge generated by the piezoelectric film 27 depends on the time derivative of the amount of bending.
  • the uniaxial stretching direction 901 is not limited to 45 degrees with respect to the Y direction and the Z direction, and may deviate by about ⁇ 10 degrees.
  • the pressure sensor 20 is connected to the display unit 104 by the adhesive 105.
  • the pressure-sensitive adhesive 105 is a material that has good workability but has a large change in elastic modulus due to temperature change.
  • the output of the pressure sensor changes.
  • the elastic modulus of the adhesive changes because the elastic modulus of the reinforcing material 21 is 10 GPa or more and the elastic modulus of the joining member 22 is 0.1 GPa or more. Output fluctuation is suppressed.
  • FIGS. 4A and 4B are cross-sectional views of the pressure sensor without the reinforcing material 21 and the joining member 22.
  • the first electrode 23, the second electrode 25, the first adhesive layer 26, the second adhesive layer 28, and the third electrode 29 are not shown.
  • FIG. 4A shows strain (stress) generated in the pressure sensor of the reference example at room temperature (25° C.).
  • FIG. 4B shows strain (stress) generated in the pressure sensor of the reference example at a low temperature (-10° C.).
  • FIGS. 5A and 5B are cross-sectional views of the pressure sensor 20 of this embodiment. However, in FIGS. 5A and 5B, the first electrode 23, the second electrode 25, the first adhesive layer 26, the second adhesive layer 28, and the third electrode 29 are not shown. ..
  • FIG. 5A shows strain (stress) generated in the pressure sensor 20 at room temperature (25° C.).
  • FIG. 5B shows the strain (stress) generated in the pressure sensor 20 at a low temperature ( ⁇ 10° C.).
  • FIGS. 6A to 6D are diagrams showing the relationship between the distance from the upper surface (starting point) of the adhesive and the strain.
  • FIG. 6A shows the distortion generated in the pressure sensor of the reference example at room temperature (25° C.).
  • FIG. 6B shows the strain (stress) generated in the pressure sensor of the reference example at a low temperature ( ⁇ 10° C.).
  • FIG. 6C shows the strain generated in the pressure sensor 20 at room temperature (25° C.).
  • FIG. 6D shows the strain (stress) generated in the pressure sensor 20 at a low temperature ( ⁇ 10° C.).
  • the vertical axes of the graphs shown in FIGS. 6A to 6D are strains, and a positive value indicates a tensile displacement, and a negative value indicates a compressive displacement. ..
  • the horizontal axis of the graphs shown in FIGS. 6A to 6D represents the distance from the lower surface (starting point) of the adhesive 105.
  • the pressure-sensitive adhesive 105 has a thickness of 100 ⁇ m
  • the piezoelectric film 27 has a thickness of 50 ⁇ m.
  • the upper surface of the piezoelectric film 27 is located 175 ⁇ m from the upper surface (starting point) of the adhesive 105, and the lower surface is located 225 ⁇ m from the starting point.
  • the reinforcing member 21 and the joining member 22 have a total thickness of 150 ⁇ m.
  • the upper surface of the piezoelectric film 27 is located at 325 ⁇ m from the starting point, and the lower surface is located at 375 ⁇ m from the starting point.
  • the display unit 104 bends in a convex shape toward the lower surface. That is, the upper surface of the display unit 104 contracts to generate compressive stress. Further, the lower surface of the display unit 104 expands to generate tensile stress. Inside the display unit 104, a neutral surface in which the tensile stress and the compressive stress are balanced and the strain becomes zero is generated.
  • a tensile stress is generated on the upper surface (starting point) of the adhesive 105 according to the extension of the lower surface of the display unit 104.
  • the tensile stress decreases as the distance from the lower surface of the display unit 104 increases.
  • a neutral plane is formed inside the adhesive 105 at normal temperature. That is, the lower surface of the adhesive agent 105 contracts to generate compressive stress.
  • Compressive stress is generated on the upper surface of the base material 24, a neutral surface is generated inside, and tensile stress is generated on the lower surface.
  • the piezoelectric film 27 generates an electric charge due to the tensile stress generated on the lower surface of the base material 24.
  • the electric charge generated in the piezoelectric film 27 is the sum of the amount of expansion generated in each position in the piezoelectric film 27.
  • the hatched area corresponds to the output of the piezoelectric film 27.
  • the elastic modulus of the pressure-sensitive adhesive 105 increases at a low temperature, and the neutral surface does not occur inside the pressure-sensitive adhesive 105. Also, in the base material 24, no neutral surface is formed inside.
  • the tensile stress of the piezoelectric film 27 is larger than that at room temperature, and the area shown by hatching is large.
  • the pressure sensor 20 has a reinforcing member 21 having an elastic modulus of 50 GPa or more and an elastic modulus.
  • the neutral surface is generated inside the reinforcing material 21 at both normal temperature and low temperature.
  • the elastic modulus of the adhesive 105 changes.
  • the pressure sensor 20 has the inside of the reinforcing material 21 or the inside of the joining member 22 at both normal temperature and low temperature. A neutral surface occurs at.
  • Tensile stress increases with distance from the neutral plane. That is, the output of the piezoelectric film 27 depends on the distance from the neutral surface closest to the piezoelectric film 27.
  • the neutral surface is generated inside the reinforcing material 21 at room temperature and at low temperature, so that the tensile stress generated in the piezoelectric film 27 does not greatly change at room temperature and at low temperature.
  • the pressure sensor 20 of the present embodiment can suppress the fluctuation of the output even if the elastic modulus of the adhesive 105 changes.
  • the pressure sensor 20 of the present embodiment includes the reinforcing material 21, the distance between the piezoelectric film 27 and the neutral surface becomes large. Therefore, the output itself of the pressure sensor 20 is also increased, and the sensitivity is improved.
  • FIG. 7A is a diagram showing the relationship between the elastic modulus of the reinforcing member 21 and the output fluctuation rate.
  • the horizontal axis of the graph is the elastic modulus of the reinforcing material 21, and the vertical axis is the output fluctuation rate.
  • the output fluctuation rate is expressed by the following relationship.
  • Output fluctuation rate (%) ((output of pressure sensor 20 at low temperature-output of pressure sensor 20 at room temperature)/output of pressure sensor 20 at room temperature) ⁇ 100
  • the graph of FIG. 7A is a simulation result under the assumption that only the elastic modulus of the adhesive 105 changes at low temperatures and high temperatures.
  • the output fluctuation rate exceeds 100% regardless of the elastic modulus of the joining member 22. Further, even when the elastic modulus of the reinforcing member 21 is 10 GPa, the output variation rate exceeds 100% except when the elastic modulus of the joining member 22 is 0.01 GPa. However, when the elastic modulus of the reinforcing material 21 reaches 50 GPa, the output fluctuation rate is greatly reduced, to about 60%.
  • FIG. 7B is a diagram showing the relationship between the elastic modulus of the joining member 22 and the output fluctuation rate when the elastic modulus of the reinforcing member 21 is 50 GPa.
  • the horizontal axis of the graph in FIG. 7B is the elastic modulus of the joining member 22, and the vertical axis is the output fluctuation rate.
  • the error bar shown in the graph of FIG. 7B indicates the fluctuation range of the output fluctuation rate when the elastic modulus of the joining member 22 varies by ⁇ 50%.
  • the output fluctuation rate is about 60%.
  • the output fluctuation rate is about 35%.
  • the fluctuation range of the output fluctuation rate with respect to the variation of the elastic modulus significantly increases.
  • the elastic modulus of the joining member 22 is 0.1 Gpa or more, the fluctuation range of the output fluctuation rate with respect to the fluctuation of the elastic modulus is small.
  • thermoplastic resin or solder shown in this embodiment is a material whose elastic modulus changes little with temperature changes.
  • the elastic modulus of the thermoplastic resin is 1 GPa, and the elastic modulus of the solder is 30 GPa. These materials satisfy the condition that the elastic modulus is 0.1 GPa.
  • the pressure sensor 20 includes the reinforcing member 21 having an elastic modulus of 50 GPa or more and the joining member 22 having an elastic modulus of 0.1 GPa or more, so that the pressure sensor 20 outputs even if the elastic modulus of the adhesive 105 changes. Can be suppressed.
  • the joining member 22 is preferably made of solder having a high elastic modulus.
  • solder When solder is used, the self-alignment effect is generated due to surface tension and the wetting of the flux, so that the reinforcing material 21 can be bonded with high positional accuracy.
  • voids spaces occur inside the solder.
  • the reinforcing material 21 is mounted by solder, a residual stress is generated when the reinforcing material 21 is hardened, but the void alleviates the residual stress.
  • the reinforcing material 21 can be joined by pressing. Therefore, it can be manufactured by a process that is easier and cheaper than mounting by soldering.
  • FIG. 8 is a diagram showing, as a reference example, the relationship between the weight and the output voltage generated in the pressure sensor when the reinforcing member 21 and the joining member 22 are not provided.
  • the detection circuit detects the bending or distortion of the housing 102 and the generated charge is converted into a voltage, and the maximum voltage V1 is generated.
  • the viscoelasticity of the adhesive agent 105 causes a voltage V2 of opposite polarity in the pressure sensor.
  • a reverse polarity maximum voltage V3 is generated in the pressure sensor.
  • a voltage V4 is generated in the pressure sensor due to the viscoelasticity of the adhesive 105.
  • the arithmetic circuit detects the pressing of the front panel 103 when the positive voltage exceeds the threshold T1, and detects the pressing of the front panel 103 when the negative voltage exceeds the threshold T2.
  • the arithmetic circuit erroneously detects pressing release.
  • the voltage V3 generated by viscoelasticity exceeds the threshold value T1
  • the arithmetic circuit erroneously detects pressing.
  • the pressure sensor 20 even if the adhesive 105 is distorted in the opposite direction due to viscoelasticity, the stiff reinforcing material 21 exists, so that the strain in the opposite direction is transmitted to the piezoelectric film 27. There is no. Therefore, as shown in FIG. 9, in the pressure sensor 20 of the present embodiment, the voltage of the opposite polarity does not occur due to the viscoelasticity of the adhesive 105.
  • FIG. 10(A) is a perspective view of the pressure sensor 30 according to the first embodiment
  • FIG. 10(B) is an exploded perspective view.
  • the pressure sensor 30 includes a strengthening plate 34, a base material 33, a piezoelectric film 32, an electrical contact portion 35, and a shield in order from the upper surface side (the lower side of the paper surface).
  • a tape 31 is provided.
  • the strengthening plate 34 has the same function as the reinforcing member 21.
  • the strengthening plate 34 may be made of a material harder than the pressure sensor 30, and is, for example, a plate formed of SUS, resin, glass or the like.
  • the pressure sensor 30 includes the bonding member 22, the first electrode 23, the second electrode 25, the first adhesive layer 26, the second adhesive layer 28, and the third electrode 29, like the pressure sensor 20, It is omitted in FIG. 10(A) and FIG. 10(B). Also, in the following figures, similarly, the joining members and the like are omitted.
  • the piezoelectric film 32 is formed shorter than the base material 33 in the Y-axis direction.
  • the shield tape 31 is shorter than the base material 33 in the Z-axis direction and longer than the piezoelectric film 32 in the Z-axis direction. Thereby, the shield tape 31 exposes a part of the base material 33 while protecting the piezoelectric film 32.
  • the electrical contact portion 35 is arranged on the exposed portion of the base material 33.
  • the strengthening plate 34 is formed to have the same size as the base material 33. Thereby, the strengthening plate 34 reinforces the entire pressure sensor 20.
  • the electrical contact portion 35 is a portion that electrically contacts the outside, and examples thereof include a connector.
  • FIGS. 11A to 11D are views showing the holding and measuring mechanism 61 of the pressure sensor 30.
  • the holding and measuring mechanism 61 includes a holding plate 37, a probe 38, a straightener 39, a holder 40, and a pusher 41.
  • the holder 40 supports one side of the pressure sensor 30.
  • the pressure sensor 30 is supported by the holder 40 on the side where the electrical contact portion 35 is arranged. Further, the holder 40 does not fix the side of the pressure sensor 30 on which the piezoelectric film 32 is arranged. Therefore, the piezoelectric film 32 can be deformed by a force from the outside while being reinforced by the reinforcing plate 34.
  • the pressing plate 37 With the pressure sensor 30 set in the holder 40, the pressing plate 37 is in a position facing the pressure sensor 30 as shown in FIG. 11(A).
  • the pressing plate 37 faces the position between the electrical contact portion 35 and the piezoelectric film 32 in the pressure sensor 30.
  • the restraining plate 37 is movable in the X-axis direction.
  • the pressing plate 37 moves in the ⁇ X direction and contacts the pressure sensor 30 as shown in FIG. 11(B).
  • the pressing plate 37 sandwiches and fixes the pressure sensor 30 with the holder 40. Accordingly, the pressing plate 37 can fix the side of the pressure sensor 30 on which the electrical contact portion 35 is provided to the holder 40 without affecting the piezoelectric film 32.
  • the probe 38 is located at a position facing the electrical contact portion 35.
  • the probe 38 is movable in the X-axis direction. By moving in the ⁇ X direction, the probe 38 comes into contact with the electrical contact portion 35, as shown in FIG. As a result, the electrical contact portion 35 can output the electric charge generated by the pressure sensor 30 to the probe 38.
  • the straightening device 39 and the pusher 41 are located opposite to each other with the piezoelectric film 32 in between.
  • the straightener 39 is located in the X direction with respect to the piezoelectric film 32, and the pusher 41 is located in the ⁇ X direction with respect to the piezoelectric film 32.
  • the straightener 39 and the pusher 41 are movable in the X-axis direction.
  • the straightener 39 moves in the ⁇ X direction, and the pusher 41 moves in the X direction to come into contact with the pressure sensor 30.
  • the straightener 39 is a roller for returning the warp of the pressure sensor 30 as described below.
  • the straightener 39 In order to restore the warp of the pressure sensor 30 by the straightener 39, compared with the case where both ends of the pressure sensor 30 are fixed by holders or the like to eliminate the warp, when the pressing force is applied to the pressure sensor 30, the pressure sensor 30 is pressed. Does not apply unnecessary tensile force.
  • the pusher 41 is a member to which a pressing force measured by the pressure sensor 30 is applied.
  • the pusher 41 moves in the X direction when a pressing force is applied.
  • the pusher 41 pushes and bends the piezoelectric film 32 in the X direction.
  • the piezoelectric film 32 is pressed and deformed to generate an electric charge.
  • FIGS. 13A and 13B are cross-sectional views showing an example of a conventional holding and measuring mechanism 131 of the pressure sensor 30 as a reference example.
  • the holding and measuring mechanism 131 will be described with reference to FIGS. 13(A) and 13(B).
  • the holding/measuring mechanism 131 includes a work placing section 140 and a pusher 141. Note that only a part of the work placing section 140 is shown.
  • the pressure sensor 30 is installed on the work rest 140.
  • the work rest part 140 supports both ends of the pressure sensor 30.
  • the work rest part 140 includes a contact probe 142 at a position facing the electrical contact part 35. When no force is applied to the pressure sensor 30, the electrical contact portion 35 contacts the contact probe 142 and is electrically connected.
  • the pusher 141 is arranged so as to face the center of the pressure sensor 30.
  • the pusher 141 When the pusher 141 is pushed in the direction of the arrow 902 shown in FIG. 13(B), the pusher 141 pushes the center of the push sensor 30.
  • the pressure sensor 30 is deformed by application of force by the pusher 141.
  • the pressure sensor 30 extends on the side farther from the pusher 141 as indicated by arrow 903, and contracts on the side closer to the pusher 141 as indicated by arrow 904.
  • the electrical contact portion 35 is separated from the contact probe 142 because the pressure sensor 30 is deformed.
  • the work placing section 140 is deformed by an external force and the electrical contact section 35 and the contact probe 142 are separated from each other. Therefore, the electrical contact portion 35 prevents the electrical connection with the contact probe 142. If the state in which the electrical contact portion 35 of the pressure sensor 30 is pressed against the contact probe 142 is maintained, the deformation of the piezoelectric film 32 is affected. Therefore, the piezoelectric film 32 cannot sufficiently output the amount of force actually applied to the pusher 141. Further, when the warp direction of the pressure sensor 30 is different, the holding and measuring mechanism 131 cannot measure accurate sensor characteristics. Therefore, the holding and measuring mechanism 131 may not be able to perform accurate measurement.
  • FIG. 12 is a flowchart of a measuring method using the holding and measuring mechanism 61 of the pressure sensor 30 according to the first embodiment.
  • the measuring method using the holding and measuring mechanism 61 will be described with reference to FIGS. 11A to 11D and 12.
  • the user sets the pressure sensor 30 on the holder 40 (S11).
  • the piezoelectric film 32 is attached to the base material 33 with some tension, the entire pressure sensor 30 may warp as shown in FIG.
  • the pressing plate 37 moves in the ⁇ X direction and contacts the pressure sensor 30 (S12).
  • the electric contact portion 35 side of the pressure sensor 30 is fixed to the holder 40.
  • the straightener 39 moves in the ⁇ X direction and comes into contact with the pressure sensor 30.
  • the straightener 39 moves in the ⁇ X direction to the position where the pressure sensor 30 becomes flat (S13). As a result, the warp of the pressure sensor 30 in the X direction is corrected.
  • the probe 38 moves in the -X direction and contacts the pressure sensor 30 (S14). As a result, the probe 38 comes into contact with the electrical contact portion 35. At this time, the probe 38 is fixed to the holder 40 while being in contact with the electrical contact portion 35. Therefore, the probe 38 is not affected even if the side of the pressure sensor 30 on which the piezoelectric film 32 is provided is deformed.
  • the pusher 41 moves in the X direction by a predetermined distance.
  • the pusher 41 moves from the flat position of the pressure sensor 30 to the position where it bends in the X direction by 0.1 mm (S15).
  • the pressure sensor 30 is in a state in which a predetermined load is applied in advance. That is, the pressure sensor 30 is applied with a load corresponding to so-called preload.
  • the piezoelectric film 32 is given a pushing load to be actually measured via the pusher 41 (S16).
  • the piezoelectric film 32 is pressed and bent in the X direction by the pusher 41 to generate an electric charge.
  • the holding/measuring mechanism 61 measures the electric charge generated by the piezoelectric film 32 (S17).
  • the pressing sensor 30 is applied with a pushing load in addition to the load corresponding to the preload. Therefore, the accuracy of the pressure sensor 30 is improved. Further, since the warp of the pressure sensor 30 is returned by the straightener 39, the amount of preload is reduced. Therefore, since the pressure sensor 30 can be brought close to the measurement condition desired by the user, the characteristics of the pressure sensor 30 close to the measurement condition desired by the user can be obtained.
  • 14A and 14B are views showing the holding and measuring mechanism 62 of the pressure sensor 50 according to the second embodiment.
  • the pressure sensor 50 and the holding measurement mechanism 62 only the points different from the holding measurement mechanism 61 according to the first embodiment will be described, and the description of the same points will be omitted.
  • the pressure sensor 50 has a configuration in which the strengthening plate 34 is removed from the pressure sensor 30. That is, the pressure sensor 50 is a flexible sensor with high flexibility.
  • the holding and measuring mechanism 62 includes a first strengthening plate 51 and a second strengthening plate 52 in addition to the holding and measuring mechanism 61.
  • the first enhancement plate 51 and the second enhancement plate 52 are made of a material harder than the pressure sensor 50.
  • the first enhancement plate 51 and the second enhancement plate 52 are flat plates having a thickness of 0.1 mm, for example. Therefore, the first reinforcing plate 51 and the second reinforcing plate 52 maintain a flat state when no force is applied, and are distorted when a certain amount of force is applied.
  • the first enhancement plate 51 is provided on the holder 40 so as to face the entire surface of the pressure sensor 50. Therefore, when the pressure sensor 50 is set on the holder 40, the pressure sensor 50 is supported along the first strengthening plate 51.
  • the second intensifying plate 52 is provided so as to face the first intensifying plate 51 so as to sandwich the pressure sensor 50.
  • the pressing plate 37 is provided on a part of the second enhancement plate 52 on the surface opposite to the pressure sensor 50. Therefore, when the pressing plate 37 moves, the second enhancement plate 52 also moves.
  • the pressing plate 37 moves in the -X direction and contacts the pressure sensor 50.
  • the pressure sensor 50 is sandwiched by the first reinforcing plate 51 and the second reinforcing plate 52.
  • the warp of the pressure sensor 50 is corrected.
  • FIG. 16(A) is a graph showing variations in measured values of Example 2 and Comparative Example. The result of repeatedly applying the same pushing load using the same pressing sensor 50 will be described.
  • the variation in the measured value of the pressure sensor 50 was about 24.5%.
  • the variation in the measurement value of the pressure sensor 50 was approximately 2%. Therefore, it was confirmed that when the first and second intensifying plates 51 and 52 were used, the dispersion of the measured values was significantly suppressed as compared with the case where the first and second intensifying plates 51 and 52 were not used. Was done.
  • 15(A) and 15(B) are views showing the holding and measuring mechanism 63 of the pressure sensor 50 according to the third embodiment.
  • the holding and measuring mechanism 63 only the points different from the holding and measuring mechanism 62 according to the second embodiment will be described, and the description of the same points will be omitted.
  • the holding measurement mechanism 63 has a configuration in which the first enhancement plate 51 is removed from the holding measurement mechanism 62. That is, the holding measurement mechanism 63 is supported by the second enhancement plate 52 only on one side of the pressure sensor 50.
  • the second intensifying plate 52 is on the side opposite to the side on which the pusher 41, to which a pushing load is applied, abuts the pressing sensor 50.
  • FIG. 16(B) is a graph showing variations in measured values of Example 3 and Comparative Example.
  • the variation in the measured values of the pressure sensor 50 was approximately 24.5%.
  • the variation in the measurement value of the pressure sensor 50 was approximately 2.5%. Therefore, it was confirmed that when the second enhancement plate 52 was used, variations in the measured values were significantly suppressed as compared with the case where the second enhancement plate 52 was not used.
  • 17(A) and 17(B) are diagrams showing the holding and measuring mechanism 64 of the pressure sensor 60 according to the fourth embodiment.
  • the holding and measuring mechanism 64 only the points different from the holding and measuring mechanism 62 according to the second embodiment will be described, and the description of the same points will be omitted.
  • the holding and measuring mechanism 64 includes a pressure sensor 60, a probe 78, a third strengthening plate 71, and a holder 70.
  • the pressure sensor 60 includes the piezoelectric film 32, the base material 33, and the electrical contact portion 35.
  • the piezoelectric film 32 and the electrical contact portion 35 are arranged on the side where the third enhancement plate 71 is arranged with respect to the base material 33.
  • the piezoelectric film 32 is attached to the base material 33 with some tension. Therefore, as shown in FIG. 17A, the entire pressure sensor 60 may warp so as to project in the X direction.
  • the probe 78 is arranged on the ⁇ X direction side with respect to the holder 70. That is, the probe 78 is arranged at a position opposite to the probe 38 of the holding and measuring mechanism 62 with respect to the electrical contact portion 35.
  • the holder 70 and the third enhancement plate 71 have holes 72 at positions corresponding to the probes 78.
  • the probe 78 moves in the X direction, the probe 78 is inserted into the hole 72.
  • the X direction side of the probe 78 inserted into the hole 72 contacts the electrical contact portion 35.
  • the measurement can be performed similarly to the holding and measuring mechanism 62.

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Abstract

A pressure sensor (20) pertaining to an embodiment of the present invention is provided with a reinforcing material (21), a joining member (22), and a sensor body 200 bonded to the reinforcing material (21) via the joining member (22). The elastic modulus of the reinforcing material (21) is at least 50 GPa, and the elastic modulus of the joining member (22) is at least 0.1 GPa.

Description

押圧センサおよび押圧検出装置Pressure sensor and pressure detection device
　本発明は、押圧を検知する押圧センサおよび該押圧センサを用いた押圧検出装置に関する。 The present invention relates to a pressure sensor for detecting pressure and a pressure detection device using the pressure sensor.
　特許文献１は、基板に圧電フィルムを貼り付けた押圧センサを開示している。 Patent Document 1 discloses a pressure sensor in which a piezoelectric film is attached to a substrate.
　特許文献１の押圧センサは、押圧センサを粘着剤でタッチパネルに貼り付けることで、タッチパネルへの押圧を検出する。 The pressure sensor of Patent Document 1 detects pressure on the touch panel by attaching the pressure sensor to the touch panel with an adhesive.
特開２０１７－１９８５７３号公報JP, 2017-198573, A
　粘着剤は、温度変化により弾性率が変化する。弾性率が変化すると、押圧センサの出力が変化する。低温時と常温時とでは、押圧センサの出力が２倍以上変わる場合もある。 The elastic modulus of the adhesive changes with changes in temperature. When the elastic modulus changes, the output of the pressure sensor changes. The output of the pressure sensor may change twice or more between low temperature and normal temperature.
　そこで、本発明は、温度変化により粘着剤の弾性率が変化しても、出力の変化を抑制することができる押圧センサおよび押圧検出装置を提供することを目的とする。 Therefore, an object of the present invention is to provide a pressure sensor and a pressure detection device capable of suppressing a change in output even if the elastic modulus of the adhesive changes due to a temperature change.
　本発明の一実施形態に係る押圧センサは、補強材と、接合部材と、前記接合部材を介して前記補強材に接着されるセンサ本体と、を備えている。 A pressure sensor according to an embodiment of the present invention includes a reinforcing material, a joining member, and a sensor body bonded to the reinforcing material via the joining member.
　そして、前記補強材の弾性率は、５０ＧＰａ以上であり、前記接合部材の弾性率は、０．１ＧＰａ以上である。押圧によって変形または歪みが発生するタッチパネルまたはスマートフォン等の筐体に粘着剤で貼り付けたとしても、硬い補強材および接合部材により、歪みの中立面が補強材の内部に存在することになり、温度に対するセンサの出力変化が抑えられる。 The elastic modulus of the reinforcing material is 50 GPa or more, and the elastic modulus of the joining member is 0.1 GPa or more. Even if it is attached to the housing of a touch panel or a smartphone that is deformed or distorted by pressing with a pressure sensitive adhesive, the neutral surface of the distortion will be present inside the reinforcing material due to the hard reinforcing material and the joining member. The output change of the sensor with respect to temperature is suppressed.
　押圧センサは、温度変化により粘着剤の弾性率が変化しても、出力の変化を抑制することができる。 The pressure sensor can suppress changes in output even if the elastic modulus of the adhesive changes due to temperature changes.
図１（Ａ）は電子機器１０１の斜視図であり、図１（Ｂ）は断面図である。1A is a perspective view of the electronic device 101, and FIG. 1B is a sectional view. 押圧センサ２０の断面図である。3 is a cross-sectional view of the pressure sensor 20. FIG. 圧電フィルム２７の平面図である。It is a top view of the piezoelectric film 27. 図４（Ａ）および図４（Ｂ）は、参考例として、補強材２１および接合部材２２を備えていない場合の押圧センサの断面図である。As a reference example, FIGS. 4A and 4B are cross-sectional views of the pressure sensor in the case where the reinforcing material 21 and the joining member 22 are not provided. 図５（Ａ）および図５（Ｂ）は、本実施形態の押圧センサ２０の断面図である。5A and 5B are cross-sectional views of the pressure sensor 20 of this embodiment. 図６（Ａ）乃至図６（Ｄ）は、粘着剤の上面（始点）からの距離と歪みの関係を示す図である。FIG. 6A to FIG. 6D are diagrams showing the relationship between the distance from the upper surface (starting point) of the adhesive and the strain. 図７（Ａ）は、補強材の弾性率と出力の変動率との関係を示す図であり、図７（Ｂ）は、補強材２１の弾性率が５０ＧＰａの場合における、接合部材２２の弾性率と出力変動率の関係を示す図である。FIG. 7(A) is a diagram showing the relationship between the elastic modulus of the reinforcing material and the fluctuation rate of the output, and FIG. 7(B) shows the elasticity of the joining member 22 when the elastic modulus of the reinforcing material 21 is 50 GPa. It is a figure which shows the relationship between a rate and an output fluctuation rate. 参考例として、補強材２１および接合部材２２を備えていない場合の押圧センサで生じる加重と出力電圧の関係を示す図である。As a reference example, it is a diagram showing the relationship between the load and the output voltage generated in the pressure sensor when the reinforcing member 21 and the joining member 22 are not provided. 本実施形態の押圧センサ２０で生じる加重と出力電圧の関係を示す図である。It is a figure which shows the relationship between the weight produced in the pressure sensor 20 of this embodiment, and an output voltage. 図１０（Ａ）は実施例１に係る押圧センサ３０の斜視図であり、図１０（Ｂ）は分解斜視図である。FIG. 10A is a perspective view of the pressure sensor 30 according to the first embodiment, and FIG. 10B is an exploded perspective view. 図１１（Ａ）乃至図１１（Ｄ）は、実施例１に係る押圧センサ３０の保持測定機構６１を示す図である。11A to 11D are views showing the holding and measuring mechanism 61 of the pressure sensor 30 according to the first embodiment. 実施例１に係る押圧センサ３０の保持測定機構６１を用いた測定方法のフローチャートである。6 is a flowchart of a measuring method using the holding and measuring mechanism 61 of the pressure sensor 30 according to the first embodiment. 図１３（Ａ）および図１３（Ｂ）は、参考例として、押圧センサ３０の従来の保持測定機構１３１の一例を示す断面図である。13A and 13B are cross-sectional views showing an example of a conventional holding and measuring mechanism 131 of the pressure sensor 30 as a reference example. 図１４（Ａ）および図１４（Ｂ）は、実施例２に係る押圧センサ５０の保持測定機構６２を示す図である。14A and 14B are views showing the holding and measuring mechanism 62 of the pressure sensor 50 according to the second embodiment. 図１５（Ａ）および図１５（Ｂ）は、実施例３に係る押圧センサ５０の保持測定機構６３を示す図である。15(A) and 15(B) are views showing the holding and measuring mechanism 63 of the pressure sensor 50 according to the third embodiment. 図１６（Ａ）は実施例２および比較例の測定値のばらつきを示すグラフであり、図１６（Ｂ）は実施例３および比較例の測定値のばらつきを示すグラフである。FIG. 16A is a graph showing the variation in the measured values of Example 2 and the comparative example, and FIG. 16B is a graph showing the variation of the measured values in Example 3 and the comparative example. 図１７（Ａ）および図１７（Ｂ）は、実施例４に係る押圧センサ６０の保持測定機構６４を示す図である。17(A) and 17(B) are diagrams showing the holding and measuring mechanism 64 of the pressure sensor 60 according to the fourth embodiment.
　図１（Ａ）は、電子機器１０１の斜視図である。図１（Ｂ）は、図１（Ａ）のＩ－Ｉ線における断面図である。本実施形態において、筐体１０２の幅方向（横方向）をＸ方向とし、長さ方向（縦方向）をＹ方向とし、厚み方向をＺ方向として説明する。 FIG. 1A is a perspective view of the electronic device 101. FIG. 1B is a cross-sectional view taken along the line II of FIG. In the present embodiment, the width direction (horizontal direction) of the housing 102 is the X direction, the length direction (longitudinal direction) is the Y direction, and the thickness direction is the Z direction.
　電子機器１０１は、本発明の押圧検出装置の一例である。電子機器１０１は、上面が開口した略直方体形状の筐体１０２を備える。電子機器１０１は、筐体１０２の上面の開口部を封止するように配置された平板状の表面パネル１０３を備えている。 The electronic device 101 is an example of the pressure detection device of the present invention. The electronic device 101 includes a casing 102 having a substantially rectangular parallelepiped shape whose upper surface is opened. The electronic device 101 includes a flat surface panel 103 arranged so as to seal the opening on the upper surface of the housing 102.
　表面パネル１０３は、利用者が指またはペン等を用いてタッチ操作を行う操作面として機能する。電子機器１０１は、筐体１０２の内側に表示部１０４、押圧センサ２０、および回路基板１１１を備えている。 The front panel 103 functions as an operation surface on which a user performs a touch operation using a finger or a pen. The electronic device 101 includes a display unit 104, a pressure sensor 20, and a circuit board 111 inside a housing 102.
　表示部１０４の第１主面（上面）は、表面パネル１０３の第２主面（下面）に貼り付けられている。押圧センサ２０は、表示部１０４の第２主面（下面）に貼り付けられている。 The first main surface (upper surface) of the display unit 104 is attached to the second main surface (lower surface) of the front panel 103. The pressure sensor 20 is attached to the second main surface (lower surface) of the display unit 104.
　図２は、押圧センサ２０の断面図である。押圧センサ２０は、粘着剤１０５で表示部１０４に貼り付けられている。押圧センサ２０および表示部１０４は、粘着剤以外の部材で接続されてもよい。ただし、粘着剤は、硬化または乾燥等の工程が不要であり、作業性が良い。電子機器１０１の製造業者は、押圧センサ２０を購入し、該押圧センサ２０を粘着剤で表示部１０４に貼り付けるだけで、押圧センサ２０を組み込むことができる。 FIG. 2 is a sectional view of the pressure sensor 20. The pressure sensor 20 is attached to the display unit 104 with an adhesive 105. The pressure sensor 20 and the display unit 104 may be connected by a member other than an adhesive. However, the pressure-sensitive adhesive does not require a step such as curing or drying and has good workability. The manufacturer of the electronic device 101 can install the pressure sensor 20 simply by purchasing the pressure sensor 20 and attaching the pressure sensor 20 to the display unit 104 with an adhesive.
　押圧センサ２０は、上面側から順に、補強材２１、接合部材２２、第１電極２３、基材２４、第２電極２５、第１接着層２６、圧電フィルム２７、第２接着層２８、および第３電極２９を備えている。第１電極２３、基材２４、第２電極２５、第１接着層２６、圧電フィルム２７、第２接着層２８、および第３電極２９によりセンサ本体２００が構成されている。 The pressure sensor 20 includes a reinforcing member 21, a joining member 22, a first electrode 23, a base material 24, a second electrode 25, a first adhesive layer 26, a piezoelectric film 27, a second adhesive layer 28, and a second adhesive layer in order from the upper surface side. 3 electrodes 29 are provided. The sensor body 200 is configured by the first electrode 23, the base material 24, the second electrode 25, the first adhesive layer 26, the piezoelectric film 27, the second adhesive layer 28, and the third electrode 29.
　補強材２１は、例えば金属材料（ＳＵＳ３０４、銅、鋳鉄、またはアルミ等）からなる。あるいは、補強材２１は、ガラスであってもよい。後述の様に、補強材２１は、少なくとも１０ＧＰａ以上の弾性率を有する。上述のＳＵＳ３０４の弾性率は１９７ＧＰａであり、銅は１１０ＧＰａ、鋳鉄は約１５２ＧＰａ、アルミは６９ＧＰａ、ガラスは８０ＧＰａであり、いずれも１０ＧＰａ以上の弾性率を有する。また、補強材２１は、押圧センサ２０を構成する部材の中で断面二次モーメントが最も大きい部材である。 The reinforcing material 21 is made of, for example, a metal material (SUS304, copper, cast iron, aluminum, etc.). Alternatively, the reinforcing material 21 may be glass. As described below, the reinforcing material 21 has an elastic modulus of at least 10 GPa or more. The elastic modulus of the above-mentioned SUS304 is 197 GPa, copper is 110 GPa, cast iron is about 152 GPa, aluminum is 69 GPa, and glass is 80 GPa, and each has an elastic modulus of 10 GPa or more. The reinforcing member 21 is a member having the largest moment of inertia of area among the members forming the pressure sensor 20.
　接合部材２２は、少なくとも０．１ＧＰａ以上の弾性率を有する。本実施形態の接合部材２２は、弾性率０．３ＧＰａの熱可塑性樹脂の接着剤からなる。接合部材２２は、温度変化に対する弾性率の変化が少ない材料であることが好ましい。接合部材２２は、少なくとも粘着剤１０５よりも温度変化に対する弾性率の変化が少ない材料である。例えば、粘着剤１０５の弾性率は、常温（２５℃）において、約０．１ＭＰａであり、低温（－２０℃）時において、約１０ＭＰａである。接合部材２２は、半田であってもよい。半田の弾性率は３０ＧＰａである。 The joining member 22 has an elastic modulus of at least 0.1 GPa or more. The joining member 22 of the present embodiment is made of a thermoplastic resin adhesive having an elastic modulus of 0.3 GPa. The joining member 22 is preferably made of a material whose elastic modulus changes little with temperature. The joining member 22 is a material in which the elastic modulus changes less with temperature changes than at least the adhesive agent 105. For example, the elastic modulus of the adhesive agent 105 is about 0.1 MPa at room temperature (25° C.) and about 10 MPa at low temperature (−20° C.). The joining member 22 may be solder. The elastic modulus of the solder is 30 GPa.
　基材２４は、例えばＰＩ（ポリイミド）またはＰＥＴ（ポリエチレンテレフタレート）等の樹脂材料からなる。基材２４の第１面には、第１電極２３が形成され、第２面には第２電極２５が形成されている。第１電極２３は、シールド電極であり、グランド電位である。補強材２１が導電性の材料であり、接合部材２２が半田である場合には、第１電極２３および補強材２１が電気的に接続される。この場合、補強材２１もシールド電極として機能する。 The base material 24 is made of a resin material such as PI (polyimide) or PET (polyethylene terephthalate). The first electrode 23 is formed on the first surface of the base material 24, and the second electrode 25 is formed on the second surface. The first electrode 23 is a shield electrode and has a ground potential. When the reinforcing material 21 is a conductive material and the joining member 22 is solder, the first electrode 23 and the reinforcing material 21 are electrically connected. In this case, the reinforcing material 21 also functions as a shield electrode.
　圧電フィルム２７の上面（第１主面）は、第１接着層２６を介して第２電極２５に接続される。圧電フィルム２７の下面（第２主面）は、第２接着層２８を介して、第３電極２９に接続される。また、押圧センサ２０を構成する部材のうち圧電フィルム２７より下面側にある部材の断面二次モーメントは、圧電フィルム２７より小さい。 The upper surface (first main surface) of the piezoelectric film 27 is connected to the second electrode 25 via the first adhesive layer 26. The lower surface (second main surface) of the piezoelectric film 27 is connected to the third electrode 29 via the second adhesive layer 28. The second moment of area of the members of the pressure sensor 20 that are on the lower surface side of the piezoelectric film 27 is smaller than that of the piezoelectric film 27.
　第２電極２５は、検出用電極であり、電圧検出用の演算回路（例えば図１（Ｂ）に示した回路基板１１１）に接続される。第３電極２９は、基準電極である。本実施形態では、第３電極２９は、グランド電位であり、シールド電極として機能する。第３電極２９は、例えば導電性シールドフィルムまたは導電性不織布からなる。導電性不織布は、圧電フィルム２７の全面を覆う様に簡単に貼り付けることができる。また、第１電極２３または補強材２１の面積が圧電フィルム２７の面積よりも大きい場合、導電性不織布を第１電極２３または補強材２１にも貼り付けることで、第３電極２９を第１電極２３または補強材２１に電気的に接続することで、シールド性を向上させることもできる。 The second electrode 25 is a detection electrode and is connected to an arithmetic circuit for voltage detection (for example, the circuit board 111 shown in FIG. 1B). The third electrode 29 is a reference electrode. In the present embodiment, the third electrode 29 has a ground potential and functions as a shield electrode. The third electrode 29 is made of, for example, a conductive shield film or a conductive non-woven fabric. The conductive non-woven fabric can be easily attached so as to cover the entire surface of the piezoelectric film 27. When the area of the first electrode 23 or the reinforcing material 21 is larger than the area of the piezoelectric film 27, the conductive non-woven fabric is also attached to the first electrode 23 or the reinforcing material 21 so that the third electrode 29 becomes the first electrode. It is also possible to improve the shielding property by electrically connecting to 23 or the reinforcing material 21.
　図３は、圧電フィルム２７を平面視した平面図である。圧電フィルム２７は、例えばキラル高分子からなる。本実施形態のキラル高分子は、Ｌ型ポリ乳酸（ＰＬＬＡ）またはＤ型ポリ乳酸（ＰＤＬＡ）からなる。 FIG. 3 is a plan view of the piezoelectric film 27 as viewed from above. The piezoelectric film 27 is made of, for example, a chiral polymer. The chiral polymer of this embodiment is composed of L-type polylactic acid (PLLA) or D-type polylactic acid (PDLA).
　ポリ乳酸は、主鎖が螺旋構造を有する。ポリ乳酸は、一軸延伸されて分子が配向すると圧電性を有する。一軸延伸されたポリ乳酸は、一軸延伸方向に対して４５度の方向に沿って伸縮すると電圧を発生する。 The main chain of polylactic acid has a helical structure. Polylactic acid has piezoelectricity when it is uniaxially stretched and molecules are oriented. The uniaxially stretched polylactic acid generates a voltage when it expands and contracts along a direction of 45 degrees with respect to the uniaxially stretched direction.
　ポリ乳酸は、延伸による分子の配向処理で圧電性を生じるため、ＰＶＤＦ等の他のポリマーまたは圧電セラミックスのように、ポーリング処理を行う必要がない。強誘電体に属さないポリ乳酸の圧電性は、ＰＶＤＦまたはＰＺＴ等の強誘電体のようにイオンの分極によって発現するものではなく、分子の特徴的な構造である螺旋構造に由来するものである。ポリ乳酸は、他の強誘電性の圧電体で生じる焦電性が生じない。したがって、ポリ乳酸は、利用者の指の温度または摩擦熱による影響を受けない。さらに、ＰＶＤＦ等は経時的に圧電定数の変動が見られ、場合によっては圧電定数が著しく低下する場合があるが、ポリ乳酸の圧電定数は経時的に極めて安定している。従って、周囲環境に影響されることなく、押圧による変位を高感度に検出することができる。ただし、圧電フィルム２７は、ポリ乳酸に限るものでなく、ポーリング処理を行ったＰＶＤＦ又はＰＺＴ等のようなイオンが分極した強誘電体から形成されるフィルムからでもよい。 Since polylactic acid produces piezoelectricity by molecular orientation treatment by stretching, it is not necessary to perform poling treatment unlike other polymers such as PVDF or piezoelectric ceramics. The piezoelectricity of polylactic acid, which does not belong to the ferroelectric substance, does not appear due to the polarization of ions unlike the ferroelectric substance such as PVDF or PZT, but is derived from the helical structure that is the characteristic structure of the molecule. .. Polylactic acid does not have the pyroelectricity that occurs with other ferroelectric piezoelectric materials. Therefore, polylactic acid is not affected by the temperature or frictional heat of the user's finger. Furthermore, the fluctuation of the piezoelectric constant of PVDF and the like is observed with the passage of time, and the piezoelectric constant may decrease remarkably in some cases, but the piezoelectric constant of polylactic acid is extremely stable with the passage of time. Therefore, the displacement due to the pressing can be detected with high sensitivity without being affected by the surrounding environment. However, the piezoelectric film 27 is not limited to polylactic acid, and may be a film formed from a ferroelectric material in which ions are polarized, such as PVDF or PZT subjected to poling treatment.
　図３に示す様に、本実施形態の圧電フィルム２７は、一軸延伸方向９０１がＹ方向およびＺ方向に対して４５度の角度を成す方向に配置されている。表面パネル１０３が押圧されると、表面パネル１０３がＹ方向およびＸ方向に撓む。したがって、圧電フィルム２７は、Ｙ方向およびＸ方向に伸張し、電荷を生じる。よって、利用者が表面パネル１０３を押圧すると、圧電フィルム２７は、電荷を生じる。圧電フィルム２７が発生する電荷量は、撓み量の時間微分に依存する。ただし、一軸延伸方向９０１は、Ｙ方向およびＺ方向に対して４５度に限らず、±１０度程度のずれがあってもよい。 As shown in FIG. 3, the piezoelectric film 27 of the present embodiment is arranged in a direction in which the uniaxial stretching direction 901 forms an angle of 45 degrees with the Y direction and the Z direction. When the front panel 103 is pressed, the front panel 103 bends in the Y direction and the X direction. Therefore, the piezoelectric film 27 stretches in the Y direction and the X direction to generate an electric charge. Therefore, when the user presses the front panel 103, the piezoelectric film 27 generates an electric charge. The amount of electric charge generated by the piezoelectric film 27 depends on the time derivative of the amount of bending. However, the uniaxial stretching direction 901 is not limited to 45 degrees with respect to the Y direction and the Z direction, and may deviate by about ±10 degrees.
　上述の様に、押圧センサ２０は、粘着剤１０５により表示部１０４に接続される。粘着剤１０５は、作業性は良いが、温度変化に対する弾性率の変化が大きい材料である。粘着剤の弾性率が変化すると、押圧センサの出力が変動する。しかし、本実施形態の押圧センサ２０は、補強材２１の弾性率が１０ＧＰａ以上であり、かつ接合部材２２の弾性率が０．１ＧＰａ以上であることにより、粘着剤の弾性率が変化しても出力の変動が抑えられる。 As described above, the pressure sensor 20 is connected to the display unit 104 by the adhesive 105. The pressure-sensitive adhesive 105 is a material that has good workability but has a large change in elastic modulus due to temperature change. When the elastic modulus of the adhesive changes, the output of the pressure sensor changes. However, in the pressure sensor 20 of the present embodiment, even if the elastic modulus of the adhesive changes because the elastic modulus of the reinforcing material 21 is 10 GPa or more and the elastic modulus of the joining member 22 is 0.1 GPa or more. Output fluctuation is suppressed.
　図４（Ａ）および図４（Ｂ）は、参考例として、補強材２１および接合部材２２を備えていない場合の押圧センサの断面図である。ただし、図４（Ａ）および図４（Ｂ）において、第１電極２３、第２電極２５、第１接着層２６、第２接着層２８、および第３電極２９は、図示を省略している。図４（Ａ）は、常温（２５℃）時に参考例の押圧センサにおいて発生する歪み（応力）を示す。図４（Ｂ）は、低温（－１０℃）時に参考例の押圧センサにおいて発生する歪み（応力）を示す。 As a reference example, FIGS. 4A and 4B are cross-sectional views of the pressure sensor without the reinforcing material 21 and the joining member 22. However, in FIGS. 4A and 4B, the first electrode 23, the second electrode 25, the first adhesive layer 26, the second adhesive layer 28, and the third electrode 29 are not shown. .. FIG. 4A shows strain (stress) generated in the pressure sensor of the reference example at room temperature (25° C.). FIG. 4B shows strain (stress) generated in the pressure sensor of the reference example at a low temperature (-10° C.).
　図５（Ａ）および図５（Ｂ）は、本実施形態の押圧センサ２０の断面図である。ただし、図５（Ａ）および図５（Ｂ）において、第１電極２３、第２電極２５、第１接着層２６、第２接着層２８、および第３電極２９は、図示を省略している。図５（Ａ）は、常温（２５℃）時に押圧センサ２０において発生する歪み（応力）を示す。図５（Ｂ）は、低温（－１０℃）時に押圧センサ２０において発生する歪み（応力）を示す。 5A and 5B are cross-sectional views of the pressure sensor 20 of this embodiment. However, in FIGS. 5A and 5B, the first electrode 23, the second electrode 25, the first adhesive layer 26, the second adhesive layer 28, and the third electrode 29 are not shown. .. FIG. 5A shows strain (stress) generated in the pressure sensor 20 at room temperature (25° C.). FIG. 5B shows the strain (stress) generated in the pressure sensor 20 at a low temperature (−10° C.).
　図６（Ａ）乃至図６（Ｄ）は、粘着剤の上面（始点）からの距離と歪みの関係を示す図である。図６（Ａ）は、常温（２５℃）時に参考例の押圧センサにおいて発生する歪みを示す。図６（Ｂ）は、低温（－１０℃）時に参考例の押圧センサにおいて発生する歪み（応力）を示す。図６（Ｃ）は、常温（２５℃）時に押圧センサ２０において発生する歪みを示す。図６（Ｄ）は、低温（－１０℃）時に押圧センサ２０において発生する歪み（応力）を示す。図６（Ａ）乃至図６（Ｄ）に示すグラフの縦軸は歪みであり、正の値を示す時には引張の変位が生じ、負の値を示す時には圧縮の変位が生じていることを示す。 6A to 6D are diagrams showing the relationship between the distance from the upper surface (starting point) of the adhesive and the strain. FIG. 6A shows the distortion generated in the pressure sensor of the reference example at room temperature (25° C.). FIG. 6B shows the strain (stress) generated in the pressure sensor of the reference example at a low temperature (−10° C.). FIG. 6C shows the strain generated in the pressure sensor 20 at room temperature (25° C.). FIG. 6D shows the strain (stress) generated in the pressure sensor 20 at a low temperature (−10° C.). The vertical axes of the graphs shown in FIGS. 6A to 6D are strains, and a positive value indicates a tensile displacement, and a negative value indicates a compressive displacement. ..
　図６（Ａ）乃至図６（Ｄ）に示すグラフの横軸は粘着剤１０５の下面（始点）からの距離を示す。図６（Ａ）乃至図６（Ｄ）のいずれの例においても、粘着剤１０５の厚みは１００μｍであり、圧電フィルム２７の厚みは５０μｍである。図６（Ａ）および図６（Ｂ）に示す参考例において、圧電フィルム２７の上面は、粘着剤１０５の上面（始点）から１７５μｍに位置し、下面は、始点から２２５μｍに位置する。図６（Ｃ）および図６（Ｄ）に示す本実施形態の押圧センサ２０において、補強材２１および接合部材２２の厚みは合わせて１５０μｍである。圧電フィルム２７の上面は、始点から３２５μｍに位置し、下面は、始点から３７５μｍに位置する。 The horizontal axis of the graphs shown in FIGS. 6A to 6D represents the distance from the lower surface (starting point) of the adhesive 105. 6A to 6D, the pressure-sensitive adhesive 105 has a thickness of 100 μm, and the piezoelectric film 27 has a thickness of 50 μm. In the reference example shown in FIGS. 6A and 6B, the upper surface of the piezoelectric film 27 is located 175 μm from the upper surface (starting point) of the adhesive 105, and the lower surface is located 225 μm from the starting point. In the pressure sensor 20 of the present embodiment shown in FIGS. 6C and 6D, the reinforcing member 21 and the joining member 22 have a total thickness of 150 μm. The upper surface of the piezoelectric film 27 is located at 325 μm from the starting point, and the lower surface is located at 375 μm from the starting point.
　利用者が表面パネル１０３を押圧すると、表示部１０４は下面方向に凸状に曲がる。つまり、表示部１０４の上面は収縮して圧縮応力が生じる。また、表示部１０４の下面は伸張して引張応力が生じる。表示部１０４の内部には、引張応力と圧縮応力とが均衡して歪みが０となる中立面が生じる。 When the user presses the front panel 103, the display unit 104 bends in a convex shape toward the lower surface. That is, the upper surface of the display unit 104 contracts to generate compressive stress. Further, the lower surface of the display unit 104 expands to generate tensile stress. Inside the display unit 104, a neutral surface in which the tensile stress and the compressive stress are balanced and the strain becomes zero is generated.
　粘着剤１０５の上面（始点）は、表示部１０４の下面の伸張に応じて、引張応力が生じる。引張応力は、表示部１０４の下面から離れるほど小さくなる。図４（Ａ）および図６（Ａ）に示す様に、参考例においては、常温時には、粘着剤１０５の内部に中立面が生じる。つまり、粘着剤１０５の下面は収縮して圧縮応力が生じる。基材２４は、上面に圧縮応力が生じ、内部に中立面が生じ、下面に引張応力が生じる。圧電フィルム２７は、基材２４の下面に生じた引張応力により電荷を生じる。圧電フィルム２７に生じる電荷は、圧電フィルム２７内の各位置に生じる伸張量の総和である。図中のグラフにおいては、ハッチングで示された面積が圧電フィルム２７の出力に相当する。 A tensile stress is generated on the upper surface (starting point) of the adhesive 105 according to the extension of the lower surface of the display unit 104. The tensile stress decreases as the distance from the lower surface of the display unit 104 increases. As shown in FIG. 4(A) and FIG. 6(A), in the reference example, a neutral plane is formed inside the adhesive 105 at normal temperature. That is, the lower surface of the adhesive agent 105 contracts to generate compressive stress. Compressive stress is generated on the upper surface of the base material 24, a neutral surface is generated inside, and tensile stress is generated on the lower surface. The piezoelectric film 27 generates an electric charge due to the tensile stress generated on the lower surface of the base material 24. The electric charge generated in the piezoelectric film 27 is the sum of the amount of expansion generated in each position in the piezoelectric film 27. In the graph in the figure, the hatched area corresponds to the output of the piezoelectric film 27.
　一方で、図４（Ｂ）および図６（Ｂ）に示す様に、参考例においては、低温時には、粘着剤１０５の弾性率が上昇し、粘着剤１０５の内部に中立面が生じない。また、基材２４においても、内部に中立面が生じない。常温時に比べて、圧電フィルム２７は、引張応力が大きくなり、ハッチングで示された面積が大きくなる。 On the other hand, as shown in FIG. 4(B) and FIG. 6(B), in the reference example, the elastic modulus of the pressure-sensitive adhesive 105 increases at a low temperature, and the neutral surface does not occur inside the pressure-sensitive adhesive 105. Also, in the base material 24, no neutral surface is formed inside. The tensile stress of the piezoelectric film 27 is larger than that at room temperature, and the area shown by hatching is large.
　つまり、参考例における押圧センサは、温度が変化すると、押圧センサの出力が大きく変動する。 That is, in the pressure sensor of the reference example, when the temperature changes, the output of the pressure sensor fluctuates greatly.
　しかし、図５（Ａ）、図５（Ｂ）、図６（Ｃ）および図６（Ｄ）に示す様に、本実施形態の押圧センサ２０は、弾性率５０ＧＰａ以上の補強材２１および弾性率０．１ＧＰａ以上の接合部材２２を備えることにより、常温時でも低温時でも、補強材２１の内部に中立面が生じる。本実施形態の押圧センサ２０においても、温度が変化すると、粘着剤１０５の弾性率は変化する。しかし、粘着剤１０５の弾性率は、低温時においても補強材２１の弾性率ほど大きくはならないため、押圧センサ２０は、常温時でも低温時でも、補強材２１の内部、または接合部材２２の内部に中立面が生じる。 However, as shown in FIGS. 5(A), 5(B), 6(C) and 6(D), the pressure sensor 20 according to the present embodiment has a reinforcing member 21 having an elastic modulus of 50 GPa or more and an elastic modulus. By providing the joining member 22 of 0.1 GPa or more, the neutral surface is generated inside the reinforcing material 21 at both normal temperature and low temperature. Also in the pressure sensor 20 of this embodiment, when the temperature changes, the elastic modulus of the adhesive 105 changes. However, since the elastic modulus of the adhesive agent 105 does not become as large as the elastic modulus of the reinforcing material 21 even at low temperature, the pressure sensor 20 has the inside of the reinforcing material 21 or the inside of the joining member 22 at both normal temperature and low temperature. A neutral surface occurs at.
　引張応力は、中立面から離れるほど大きくなる。つまり、圧電フィルム２７の出力は、圧電フィルム２７に最も近い中立面からの距離に依存する。本実施形態の押圧センサ２０は、常温時でも低温時でも、補強材２１の内部に中立面が生じるため、圧電フィルム２７に生じる引張応力は、常温時でも低温時でも、大きく変わらない。 Tensile stress increases with distance from the neutral plane. That is, the output of the piezoelectric film 27 depends on the distance from the neutral surface closest to the piezoelectric film 27. In the pressure sensor 20 of the present embodiment, the neutral surface is generated inside the reinforcing material 21 at room temperature and at low temperature, so that the tensile stress generated in the piezoelectric film 27 does not greatly change at room temperature and at low temperature.
　よって、本実施形態の押圧センサ２０は、粘着剤１０５の弾性率が変化しても出力の変動を抑制することができる。 Therefore, the pressure sensor 20 of the present embodiment can suppress the fluctuation of the output even if the elastic modulus of the adhesive 105 changes.
　なお、図６（Ａ）および図６（Ｃ）の比較の通り、本実施形態の押圧センサ２０は、補強材２１を備えるため、圧電フィルム２７と中立面との距離が大きくなる。したがって、押圧センサ２０の出力自体も大きくなり、感度が向上する。 As compared with FIG. 6(A) and FIG. 6(C), since the pressure sensor 20 of the present embodiment includes the reinforcing material 21, the distance between the piezoelectric film 27 and the neutral surface becomes large. Therefore, the output itself of the pressure sensor 20 is also increased, and the sensitivity is improved.
　次に、図７（Ａ）は、補強材２１の弾性率と出力変動率との関係を示す図である。グラフの横軸は、補強材２１の弾性率であり、縦軸は出力変動率である。出力変動率は、以下の関係で表される。　
　出力変動率（％）＝（（低温時の押圧センサ２０の出力－常温時の押圧センサ２０の出力）／常温時の押圧センサ２０の出力）×１００　
　ただし、図７（Ａ）のグラフは、低温時および高温時で、粘着剤１０５の弾性率のみ変化すると仮定した場合のシミュレーション結果である。 Next, FIG. 7A is a diagram showing the relationship between the elastic modulus of the reinforcing member 21 and the output fluctuation rate. The horizontal axis of the graph is the elastic modulus of the reinforcing material 21, and the vertical axis is the output fluctuation rate. The output fluctuation rate is expressed by the following relationship.
Output fluctuation rate (%)=((output of pressure sensor 20 at low temperature-output of pressure sensor 20 at room temperature)/output of pressure sensor 20 at room temperature)×100
However, the graph of FIG. 7A is a simulation result under the assumption that only the elastic modulus of the adhesive 105 changes at low temperatures and high temperatures.
　図７（Ａ）に示す様に、補強材２１の弾性率が１ＧＰａの場合、接合部材２２の弾性率に関わらず、出力変動率は１００％を超える。また、補強材２１の弾性率が１０ＧＰａの場合でも、出力変動率は、接合部材２２の弾性率が０．０１ＧＰａである場合を除き、１００％を超える。しかし、補強材２１の弾性率が５０ＧＰａになると、出力変動率は大きく低下し、概ね６０％程度に低下する。 As shown in FIG. 7A, when the elastic modulus of the reinforcing material 21 is 1 GPa, the output fluctuation rate exceeds 100% regardless of the elastic modulus of the joining member 22. Further, even when the elastic modulus of the reinforcing member 21 is 10 GPa, the output variation rate exceeds 100% except when the elastic modulus of the joining member 22 is 0.01 GPa. However, when the elastic modulus of the reinforcing material 21 reaches 50 GPa, the output fluctuation rate is greatly reduced, to about 60%.
　図７（Ｂ）は、補強材２１の弾性率が５０ＧＰａの場合における、接合部材２２の弾性率と出力変動率の関係を示す図である。図７（Ｂ）のグラフの横軸は、接合部材２２の弾性率であり、縦軸は出力変動率である。図７（Ｂ）のグラフに示すエラーバーは、接合部材２２の弾性率が±５０％ばらついた場合の出力変動率の変動幅を示す。 FIG. 7B is a diagram showing the relationship between the elastic modulus of the joining member 22 and the output fluctuation rate when the elastic modulus of the reinforcing member 21 is 50 GPa. The horizontal axis of the graph in FIG. 7B is the elastic modulus of the joining member 22, and the vertical axis is the output fluctuation rate. The error bar shown in the graph of FIG. 7B indicates the fluctuation range of the output fluctuation rate when the elastic modulus of the joining member 22 varies by ±50%.
　図７（Ｂ）に示すように、接合部材２２の弾性率が０．１ＧＰａ以上の場合、出力変動率は、概ね６０％程度である。接合部材２２の弾性率が０．０１Ｇｐａの場合、出力変動率は、３５％程度である。しかし、接合部材２２の弾性率が０．０１Ｇｐａの場合、弾性率のばらつきに対する出力変動率の変動幅は、著しく増大する。一方で、接合部材２２の弾性率が０．１Ｇｐａ以上の場合、弾性率のばらつきに対する出力変動率の変動幅は、小さい。 As shown in FIG. 7B, when the elastic modulus of the joining member 22 is 0.1 GPa or more, the output fluctuation rate is about 60%. When the elastic modulus of the joining member 22 is 0.01 Gpa, the output fluctuation rate is about 35%. However, when the elastic modulus of the joining member 22 is 0.01 Gpa, the fluctuation range of the output fluctuation rate with respect to the variation of the elastic modulus significantly increases. On the other hand, when the elastic modulus of the joining member 22 is 0.1 Gpa or more, the fluctuation range of the output fluctuation rate with respect to the fluctuation of the elastic modulus is small.
　したがって、接合部材２２の弾性率が０．１ＧＰａ以上である場合に、接合部材２２の弾性率のばらつきによる影響が小さくなる。本実施形態で示した熱可塑性樹脂または半田は、温度変化による弾性率の変化が小さい材料である。熱可塑性樹脂の弾性率は１ＧＰａであり、半田の弾性率は３０ＧＰａである。これらの材料は、弾性率０．１ＧＰａの条件を満たしている。 Therefore, when the elastic modulus of the joining member 22 is 0.1 GPa or more, the influence of the variation in the elastic modulus of the joining member 22 is reduced. The thermoplastic resin or solder shown in this embodiment is a material whose elastic modulus changes little with temperature changes. The elastic modulus of the thermoplastic resin is 1 GPa, and the elastic modulus of the solder is 30 GPa. These materials satisfy the condition that the elastic modulus is 0.1 GPa.
　これらの例から、押圧センサ２０は、弾性率が５０ＧＰａ以上の補強材２１と、弾性率が０．１ＧＰａ以上の接合部材２２とを備えることにより、粘着剤１０５の弾性率が変化しても出力の変動を抑制することができる。 From these examples, the pressure sensor 20 includes the reinforcing member 21 having an elastic modulus of 50 GPa or more and the joining member 22 having an elastic modulus of 0.1 GPa or more, so that the pressure sensor 20 outputs even if the elastic modulus of the adhesive 105 changes. Can be suppressed.
　接合部材２２は、弾性率の高い半田を用いることが好ましい。半田を用いた場合、表面張力とフラックスの濡れ上がりによりセルフアライメント効果が生じて、補強材２１を高い位置精度で接合することができる。また、半田の内部にはボイド（空間）が生じる。半田により補強材２１を実装すると、硬化する時に残留応力が生じるが、このボイドにより、当該残留応力が緩和される。 The joining member 22 is preferably made of solder having a high elastic modulus. When solder is used, the self-alignment effect is generated due to surface tension and the wetting of the flux, so that the reinforcing material 21 can be bonded with high positional accuracy. In addition, voids (spaces) occur inside the solder. When the reinforcing material 21 is mounted by solder, a residual stress is generated when the reinforcing material 21 is hardened, but the void alleviates the residual stress.
　一方で、熱可塑性樹脂を用いる場合には、プレス加工により補強材２１を接合することができる。したがって、半田による実装よりも容易かつ安価なプロセスで製造できる。 On the other hand, when a thermoplastic resin is used, the reinforcing material 21 can be joined by pressing. Therefore, it can be manufactured by a process that is easier and cheaper than mounting by soldering.
　なお、粘着剤１０５は、粘弾性体である。粘着剤１０５は、粘弾性により、歪みを元の状態に戻そうとする力が生じる。図８は、参考例として、補強材２１および接合部材２２を備えていない場合の押圧センサで生じる加重と出力電圧の関係を示す図である。 Note that the adhesive 105 is a viscoelastic body. Due to viscoelasticity, the adhesive agent 105 generates a force to return the strain to the original state. FIG. 8 is a diagram showing, as a reference example, the relationship between the weight and the output voltage generated in the pressure sensor when the reinforcing member 21 and the joining member 22 are not provided.
　この例において、利用者が表面パネル１０３を押圧すると、筐体１０２の曲げまたは歪みを押圧センサが検知して発生した電荷が検出回路によって電圧に変換され、最大電圧Ｖ１が生じる。ここで、利用者の加重が一定になった場合、粘着剤１０５の粘弾性より、押圧センサにおいて逆極性の電圧Ｖ２が生じる。また、利用者が表面パネル１０３の押圧を緩めると、押圧センサにおいて逆極性の最大電圧Ｖ３が生じる。利用者が表面パネル１０３の押圧を解除すると、粘着剤１０５の粘弾性より、押圧センサにおいて電圧Ｖ４が生じる。 In this example, when the user presses the surface panel 103, the detection circuit detects the bending or distortion of the housing 102 and the generated charge is converted into a voltage, and the maximum voltage V1 is generated. Here, when the weight of the user is constant, the viscoelasticity of the adhesive agent 105 causes a voltage V2 of opposite polarity in the pressure sensor. Further, when the user loosens the pressure on the front panel 103, a reverse polarity maximum voltage V3 is generated in the pressure sensor. When the user releases the pressure on the front panel 103, a voltage V4 is generated in the pressure sensor due to the viscoelasticity of the adhesive 105.
　演算回路においては、正の電圧が閾値Ｔ１を超えた場合に表面パネル１０３の押圧を検出し、負の電圧が閾値Ｔ２を超えた場合に表面パネル１０３の押圧解除を検出する。しかし、図８に示す様に、粘弾性により生じる逆極性の電圧Ｖ２が閾値Ｔ２を超えると、演算回路は、押圧解除を誤検出する。また、粘弾性により生じる電圧Ｖ３が閾値Ｔ１を超えると、演算回路は、押圧を誤検出する。 The arithmetic circuit detects the pressing of the front panel 103 when the positive voltage exceeds the threshold T1, and detects the pressing of the front panel 103 when the negative voltage exceeds the threshold T2. However, as shown in FIG. 8, when the reverse polarity voltage V2 generated by viscoelasticity exceeds the threshold value T2, the arithmetic circuit erroneously detects pressing release. When the voltage V3 generated by viscoelasticity exceeds the threshold value T1, the arithmetic circuit erroneously detects pressing.
　これに対して、本実施形態の押圧センサ２０は、粘着剤１０５において粘弾性により逆方向の歪みが生じても、硬い補強材２１が存在するため、圧電フィルム２７に逆方向の歪みが伝わることがない。したがって、図９に示す様に、本実施形態の押圧センサ２０は、粘着剤１０５の粘弾性によって逆極性の電圧が生じることはない。 On the other hand, in the pressure sensor 20 according to the present embodiment, even if the adhesive 105 is distorted in the opposite direction due to viscoelasticity, the stiff reinforcing material 21 exists, so that the strain in the opposite direction is transmitted to the piezoelectric film 27. There is no. Therefore, as shown in FIG. 9, in the pressure sensor 20 of the present embodiment, the voltage of the opposite polarity does not occur due to the viscoelasticity of the adhesive 105.
　次に、図１０（Ａ）は実施例１に係る押圧センサ３０の斜視図であり、図１０（Ｂ）は分解斜視図である。 Next, FIG. 10(A) is a perspective view of the pressure sensor 30 according to the first embodiment, and FIG. 10(B) is an exploded perspective view.
　図１０（Ａ）および図１０（Ｂ）に示すように、押圧センサ３０は、上面側（紙面下方）から順に、増強板３４、基材３３、圧電フィルム３２、電気的接触部３５、およびシールドテープ３１を備える。増強板３４は、補強材２１と同じ機能を有する。増強板３４は、押圧センサ３０より硬い素材であればよく、例えばＳＵＳや樹脂、ガラスなどで形成された板である。なお、押圧センサ３０は、押圧センサ２０と同様に、接合部材２２、第１電極２３、第２電極２５、第１接着層２６、第２接着層２８、および第３電極２９を備えるが、図１０（Ａ）および図１０（Ｂ）においては省略して表す。また、以降の図においても同様に接合部材等は省略する。 As shown in FIGS. 10A and 10B, the pressure sensor 30 includes a strengthening plate 34, a base material 33, a piezoelectric film 32, an electrical contact portion 35, and a shield in order from the upper surface side (the lower side of the paper surface). A tape 31 is provided. The strengthening plate 34 has the same function as the reinforcing member 21. The strengthening plate 34 may be made of a material harder than the pressure sensor 30, and is, for example, a plate formed of SUS, resin, glass or the like. Note that the pressure sensor 30 includes the bonding member 22, the first electrode 23, the second electrode 25, the first adhesive layer 26, the second adhesive layer 28, and the third electrode 29, like the pressure sensor 20, It is omitted in FIG. 10(A) and FIG. 10(B). Also, in the following figures, similarly, the joining members and the like are omitted.
　圧電フィルム３２は、基材３３よりＹ軸方向に対して短く形成されている。シールドテープ３１は、基材３３よりＺ軸方向に対して短く、かつ圧電フィルム３２よりＺ軸方向に対して長く形成されている。これにより、シールドテープ３１は、圧電フィルム３２を保護しつつ基材３３の一部を露出している。電気的接触部３５は、基材３３の露出された部分に配置されている。増強板３４は、基材３３と同じ大きさに形成されている。これにより、増強板３４は、押圧センサ２０全体を補強する。なお、電気的接触部３５は、電気的に外部と接触する部分であり、例えばコネクタなどが挙げられる。 The piezoelectric film 32 is formed shorter than the base material 33 in the Y-axis direction. The shield tape 31 is shorter than the base material 33 in the Z-axis direction and longer than the piezoelectric film 32 in the Z-axis direction. Thereby, the shield tape 31 exposes a part of the base material 33 while protecting the piezoelectric film 32. The electrical contact portion 35 is arranged on the exposed portion of the base material 33. The strengthening plate 34 is formed to have the same size as the base material 33. Thereby, the strengthening plate 34 reinforces the entire pressure sensor 20. The electrical contact portion 35 is a portion that electrically contacts the outside, and examples thereof include a connector.
　図１１（Ａ）乃至図１１（Ｄ）は、押圧センサ３０の保持測定機構６１を示す図である。図１１（Ａ）乃至図１１（Ｄ）に示すように、保持測定機構６１は、抑え板３７、プローブ３８、矯正機３９、ホルダ４０、および押し子４１を備える。 11A to 11D are views showing the holding and measuring mechanism 61 of the pressure sensor 30. As shown in FIGS. 11A to 11D, the holding and measuring mechanism 61 includes a holding plate 37, a probe 38, a straightener 39, a holder 40, and a pusher 41.
　ホルダ４０は、押圧センサ３０の片側を支持する。押圧センサ３０は、電気的接触部３５が配置されている側でホルダ４０に支持されている。また、ホルダ４０は、押圧センサ３０のうち圧電フィルム３２が配置されている側を固定しない。このため、圧電フィルム３２は、増強板３４によって補強されつつ、外部から力により変形することができる。 The holder 40 supports one side of the pressure sensor 30. The pressure sensor 30 is supported by the holder 40 on the side where the electrical contact portion 35 is arranged. Further, the holder 40 does not fix the side of the pressure sensor 30 on which the piezoelectric film 32 is arranged. Therefore, the piezoelectric film 32 can be deformed by a force from the outside while being reinforced by the reinforcing plate 34.
　押圧センサ３０がホルダ４０にセットされた状態で、抑え板３７は、図１１（Ａ）に示すように、押圧センサ３０と対向する位置にある。抑え板３７は、押圧センサ３０における電気的接触部３５と圧電フィルム３２との間の位置に対向する。抑え板３７は、Ｘ軸方向に移動可能である。抑え板３７は、－Ｘ方向に移動し、図１１（Ｂ）に示すように、押圧センサ３０に当接する。抑え板３７は、ホルダ４０との間で押圧センサ３０を挟み込み固定する。これにより、抑え板３７は、圧電フィルム３２に影響なく押圧センサ３０の電気的接触部３５が設けられた側をホルダ４０に固定することができる。 With the pressure sensor 30 set in the holder 40, the pressing plate 37 is in a position facing the pressure sensor 30 as shown in FIG. 11(A). The pressing plate 37 faces the position between the electrical contact portion 35 and the piezoelectric film 32 in the pressure sensor 30. The restraining plate 37 is movable in the X-axis direction. The pressing plate 37 moves in the −X direction and contacts the pressure sensor 30 as shown in FIG. 11(B). The pressing plate 37 sandwiches and fixes the pressure sensor 30 with the holder 40. Accordingly, the pressing plate 37 can fix the side of the pressure sensor 30 on which the electrical contact portion 35 is provided to the holder 40 without affecting the piezoelectric film 32.
　プローブ３８は、電気的接触部３５と対向する位置にある。プローブ３８は、Ｘ軸方向に移動可能である。プローブ３８は、－Ｘ方向に移動することにより、図１１（Ｃ）に示すように、電気的接触部３５と当接する。これにより、電気的接触部３５は、押圧センサ３０で発生する電荷をプローブ３８へ出力することができる。 The probe 38 is located at a position facing the electrical contact portion 35. The probe 38 is movable in the X-axis direction. By moving in the −X direction, the probe 38 comes into contact with the electrical contact portion 35, as shown in FIG. As a result, the electrical contact portion 35 can output the electric charge generated by the pressure sensor 30 to the probe 38.
　矯正機３９および押し子４１は、圧電フィルム３２を挟んで対向する位置にある。矯正機３９は圧電フィルム３２に対してＸ方向に、押し子４１は圧電フィルム３２に対して－Ｘ方向にそれぞれ位置する。矯正機３９および押し子４１は、Ｘ軸方向に移動可能である。矯正機３９は－Ｘ方向に移動することにより、押し子４１はＸ方向に移動することにより、それぞれ押圧センサ３０と当接する。 The straightening device 39 and the pusher 41 are located opposite to each other with the piezoelectric film 32 in between. The straightener 39 is located in the X direction with respect to the piezoelectric film 32, and the pusher 41 is located in the −X direction with respect to the piezoelectric film 32. The straightener 39 and the pusher 41 are movable in the X-axis direction. The straightener 39 moves in the −X direction, and the pusher 41 moves in the X direction to come into contact with the pressure sensor 30.
　矯正機３９は、以下で説明するように押圧センサ３０の反りを戻すためのローラである。押圧センサ３０の反りを矯正機３９で戻すために、押圧センサ３０の両端をホルダ等で固定して反りをなくす場合に比べて、押圧センサ３０に押圧する力が付与された時に、押圧センサ３０は不要な引張力がかけられない。 The straightener 39 is a roller for returning the warp of the pressure sensor 30 as described below. In order to restore the warp of the pressure sensor 30 by the straightener 39, compared with the case where both ends of the pressure sensor 30 are fixed by holders or the like to eliminate the warp, when the pressing force is applied to the pressure sensor 30, the pressure sensor 30 is pressed. Does not apply unnecessary tensile force.
　押し子４１は、押圧センサ３０が測定する押圧する力がかけられる部材である。押し子４１は、押圧する力が付与されることにより、Ｘ方向に移動する。これにより、押し子４１は、圧電フィルム３２をＸ方向に押し曲げる。圧電フィルム３２は、押し曲げられて変形することにより電荷を発生する。 The pusher 41 is a member to which a pressing force measured by the pressure sensor 30 is applied. The pusher 41 moves in the X direction when a pressing force is applied. As a result, the pusher 41 pushes and bends the piezoelectric film 32 in the X direction. The piezoelectric film 32 is pressed and deformed to generate an electric charge.
　図１３（Ａ）および図１３（Ｂ）は、参考例として、押圧センサ３０の従来の保持測定機構１３１の一例を示す断面図である。ここで、図１３（Ａ）および図１３（Ｂ）を参照しながら、保持測定機構１３１について説明する。 FIGS. 13A and 13B are cross-sectional views showing an example of a conventional holding and measuring mechanism 131 of the pressure sensor 30 as a reference example. Here, the holding and measuring mechanism 131 will be described with reference to FIGS. 13(A) and 13(B).
　図１３（Ａ）に示すように、保持測定機構１３１は、ワーク置き部１４０と押し子１４１を備える。なお、ワーク置き部１４０については、一部のみを表している。押圧センサ３０は、ワーク置き部１４０に設置されている。ワーク置き部１４０は、押圧センサ３０の両端を支持する。ワーク置き部１４０は、電気的接触部３５と対向する位置にコンタクトプローブ１４２を備える。押圧センサ３０に力が加えられていないとき、電気的接触部３５は、コンタクトプローブ１４２と接触し、電気的に接続されている。押し子１４１は、押圧センサ３０の中央と対向するように配置されている。 As shown in FIG. 13A, the holding/measuring mechanism 131 includes a work placing section 140 and a pusher 141. Note that only a part of the work placing section 140 is shown. The pressure sensor 30 is installed on the work rest 140. The work rest part 140 supports both ends of the pressure sensor 30. The work rest part 140 includes a contact probe 142 at a position facing the electrical contact part 35. When no force is applied to the pressure sensor 30, the electrical contact portion 35 contacts the contact probe 142 and is electrically connected. The pusher 141 is arranged so as to face the center of the pressure sensor 30.
　押し子１４１を図１３（Ｂ）に示す矢印９０２の方向へ押した場合に、押し子１４１は、押圧センサ３０の中央を押す。押圧センサ３０は、押し子１４１による力の付与により変形する。押圧センサ３０は、押し子１４１から遠い側が矢印９０３で示すように伸び、押し子１４１に近い側が矢印９０４で示すように縮む。この時、電気的接触部３５は、押圧センサ３０の変形するため、コンタクトプローブ１４２から離れる。 When the pusher 141 is pushed in the direction of the arrow 902 shown in FIG. 13(B), the pusher 141 pushes the center of the push sensor 30. The pressure sensor 30 is deformed by application of force by the pusher 141. The pressure sensor 30 extends on the side farther from the pusher 141 as indicated by arrow 903, and contracts on the side closer to the pusher 141 as indicated by arrow 904. At this time, the electrical contact portion 35 is separated from the contact probe 142 because the pressure sensor 30 is deformed.
　また、外部からの力によりワーク置き部１４０が変形して、電気的接触部３５とコンタクトプローブ１４２とが離れる場合もある。従って、電気的接触部３５は、コンタクトプローブ１４２との電気的な接続が妨げられる。押圧センサ３０の電気的接触部３５をコンタクトプローブ１４２と接触するように押し当てた状態を維持すると、圧電フィルム３２の変形に影響する。このため、圧電フィルム３２は、実際に押し子１４１に加えた力の分が十分に出力できない。さらに、押圧センサ３０の反り方向が異なる場合、保持測定機構１３１は、正確なセンサ特性を測定できない。したがって、保持測定機構１３１は、正確な測定ができないおそれがある。 There is also a case where the work placing section 140 is deformed by an external force and the electrical contact section 35 and the contact probe 142 are separated from each other. Therefore, the electrical contact portion 35 prevents the electrical connection with the contact probe 142. If the state in which the electrical contact portion 35 of the pressure sensor 30 is pressed against the contact probe 142 is maintained, the deformation of the piezoelectric film 32 is affected. Therefore, the piezoelectric film 32 cannot sufficiently output the amount of force actually applied to the pusher 141. Further, when the warp direction of the pressure sensor 30 is different, the holding and measuring mechanism 131 cannot measure accurate sensor characteristics. Therefore, the holding and measuring mechanism 131 may not be able to perform accurate measurement.
　図１２は、実施例１に係る押圧センサ３０の保持測定機構６１を用いた測定方法のフローチャートである。以下、図１１（Ａ）乃至図１１（Ｄ）、および図１２を参照しながら保持測定機構６１を用いた測定方法の説明をする。 FIG. 12 is a flowchart of a measuring method using the holding and measuring mechanism 61 of the pressure sensor 30 according to the first embodiment. Hereinafter, the measuring method using the holding and measuring mechanism 61 will be described with reference to FIGS. 11A to 11D and 12.
　図１１（Ａ）に示すように、ユーザは、ホルダ４０に押圧センサ３０をセットする（Ｓ１１）。ここで、圧電フィルム３２をある程度張力をもって基材３３に貼り付けると、図１１（Ａ）に示すように、押圧センサ３０全体が反る場合がある。 As shown in FIG. 11A, the user sets the pressure sensor 30 on the holder 40 (S11). Here, if the piezoelectric film 32 is attached to the base material 33 with some tension, the entire pressure sensor 30 may warp as shown in FIG.
　図１１（Ｂ）に示すように、抑え板３７は－Ｘ方向に移動し、押圧センサ３０に当接する（Ｓ１２）。これにより、押圧センサ３０の電気的接触部３５側がホルダ４０に固定される。次に、矯正機３９は－Ｘ方向に移動し、押圧センサ３０に当接する。また、矯正機３９は、押圧センサ３０が平らになる位置まで－Ｘ方向に移動する（Ｓ１３）。これにより、押圧センサ３０のＸ方向への反りが矯正される。 As shown in FIG. 11(B), the pressing plate 37 moves in the −X direction and contacts the pressure sensor 30 (S12). As a result, the electric contact portion 35 side of the pressure sensor 30 is fixed to the holder 40. Next, the straightener 39 moves in the −X direction and comes into contact with the pressure sensor 30. Further, the straightener 39 moves in the −X direction to the position where the pressure sensor 30 becomes flat (S13). As a result, the warp of the pressure sensor 30 in the X direction is corrected.
　さらに、プローブ３８は－Ｘ方向に移動し、押圧センサ３０に当接する（Ｓ１４）。これにより、プローブ３８は、電気的接触部３５と接触する。このとき、プローブ３８は、電気的接触部３５と接触した状態でホルダ４０に固定される。したがって、プローブ３８は、押圧センサ３０の圧電フィルム３２が設けられた側が変形しても影響を受けない。 Further, the probe 38 moves in the -X direction and contacts the pressure sensor 30 (S14). As a result, the probe 38 comes into contact with the electrical contact portion 35. At this time, the probe 38 is fixed to the holder 40 while being in contact with the electrical contact portion 35. Therefore, the probe 38 is not affected even if the side of the pressure sensor 30 on which the piezoelectric film 32 is provided is deformed.
　次に、図１１（Ｃ）に示すように押し子４１は、Ｘ方向に所定の距離分移動する。例えば、押し子４１は、押圧センサ３０が平らな位置からＸ方向に０．１ｍｍ撓む位置まで移動する（Ｓ１５）。これにより、押圧センサ３０は、あらかじめ所定の荷重が付与された状態となる。すなわち、押圧センサ３０は、いわゆるプリロードに対応する荷重が付与されている。 Next, as shown in FIG. 11C, the pusher 41 moves in the X direction by a predetermined distance. For example, the pusher 41 moves from the flat position of the pressure sensor 30 to the position where it bends in the X direction by 0.1 mm (S15). As a result, the pressure sensor 30 is in a state in which a predetermined load is applied in advance. That is, the pressure sensor 30 is applied with a load corresponding to so-called preload.
　引き継き、図１１（Ｄ）に示すように、圧電フィルム３２は、押し子４１を介して実際に測定する押し込み荷重を付与される（Ｓ１６）。圧電フィルム３２は、押し子４１によりＸ方向に押し曲げられ、電荷を発生する。保持測定機構６１は、圧電フィルム３２が発生する電荷を測定する（Ｓ１７）。押圧センサ３０は、プリロードに対応する荷重に加えて押し込み荷重が付与される。このため、押圧センサ３０の精度が高まる。また、押圧センサ３０の反りを矯正機３９で戻すために、プリロードの量が低減される。したがって、押圧センサ３０はユーザが使用したい測定条件に近づけることができるため、ユーザが使用したい測定条件に近い押圧センサ３０の特性が得られる。 Subsequently, as shown in FIG. 11D, the piezoelectric film 32 is given a pushing load to be actually measured via the pusher 41 (S16). The piezoelectric film 32 is pressed and bent in the X direction by the pusher 41 to generate an electric charge. The holding/measuring mechanism 61 measures the electric charge generated by the piezoelectric film 32 (S17). The pressing sensor 30 is applied with a pushing load in addition to the load corresponding to the preload. Therefore, the accuracy of the pressure sensor 30 is improved. Further, since the warp of the pressure sensor 30 is returned by the straightener 39, the amount of preload is reduced. Therefore, since the pressure sensor 30 can be brought close to the measurement condition desired by the user, the characteristics of the pressure sensor 30 close to the measurement condition desired by the user can be obtained.
　以下、実施例２に係る保持測定機構６２について説明する。図１４（Ａ）および図１４（Ｂ）は、実施例２に係る押圧センサ５０の保持測定機構６２を示す図である。押圧センサ５０および保持測定機構６２の説明においては、実施例１に係る保持測定機構６１と異なる点についてのみ説明を行い、同様の点については説明を省略する。 Hereinafter, the holding and measuring mechanism 62 according to the second embodiment will be described. 14A and 14B are views showing the holding and measuring mechanism 62 of the pressure sensor 50 according to the second embodiment. In the description of the pressure sensor 50 and the holding measurement mechanism 62, only the points different from the holding measurement mechanism 61 according to the first embodiment will be described, and the description of the same points will be omitted.
　図１４（Ａ）および図１４（Ｂ）に示すように、押圧センサ５０は、押圧センサ３０から増強板３４を除いた構成である。すなわち、押圧センサ５０は、柔軟性に富むフレキシブルなセンサである。 As shown in FIGS. 14(A) and 14(B), the pressure sensor 50 has a configuration in which the strengthening plate 34 is removed from the pressure sensor 30. That is, the pressure sensor 50 is a flexible sensor with high flexibility.
　保持測定機構６２は、保持測定機構６１に加えて第１増強板５１、および第２増強板５２を備える。第１増強板５１および第２増強板５２は、押圧センサ５０より硬い素材から形成されている。第１増強板５１および第２増強板５２は、例えば０．１ｍｍの厚さの平板である。このため、第１増強板５１および第２増強板５２は、力が加えられていない状態では平らな状態を維持し、ある程度の力が加えられると歪む。 The holding and measuring mechanism 62 includes a first strengthening plate 51 and a second strengthening plate 52 in addition to the holding and measuring mechanism 61. The first enhancement plate 51 and the second enhancement plate 52 are made of a material harder than the pressure sensor 50. The first enhancement plate 51 and the second enhancement plate 52 are flat plates having a thickness of 0.1 mm, for example. Therefore, the first reinforcing plate 51 and the second reinforcing plate 52 maintain a flat state when no force is applied, and are distorted when a certain amount of force is applied.
　第１増強板５１は、ホルダ４０に押圧センサ５０の全面と対向するように設けられている。このため、ホルダ４０に押圧センサ５０をセットすると、押圧センサ５０は第１増強板５１に沿って支持される。第２増強板５２は、押圧センサ５０を挟み込むように第１増強板５１と対向するように設けられている。抑え板３７は、第２増強板５２の一部に押圧センサ５０に対して逆の面に設けられている。このため、抑え板３７が移動すると、第２増強板５２もともに移動する。 The first enhancement plate 51 is provided on the holder 40 so as to face the entire surface of the pressure sensor 50. Therefore, when the pressure sensor 50 is set on the holder 40, the pressure sensor 50 is supported along the first strengthening plate 51. The second intensifying plate 52 is provided so as to face the first intensifying plate 51 so as to sandwich the pressure sensor 50. The pressing plate 37 is provided on a part of the second enhancement plate 52 on the surface opposite to the pressure sensor 50. Therefore, when the pressing plate 37 moves, the second enhancement plate 52 also moves.
　抑え板３７は－Ｘ方向に移動し、押圧センサ５０に当接する。図１４（Ｂ）に示すように、押圧センサ５０は、第１増強板５１および第２増強板５２により挟み込まれる。これにより、押圧センサ５０は、反りが矯正される。押圧センサ５０は、反りが矯正されることにより、以下のように測定値のばらつきが抑制される。 The pressing plate 37 moves in the -X direction and contacts the pressure sensor 50. As shown in FIG. 14B, the pressure sensor 50 is sandwiched by the first reinforcing plate 51 and the second reinforcing plate 52. As a result, the warp of the pressure sensor 50 is corrected. By correcting the warp of the pressure sensor 50, variations in measured values are suppressed as follows.
　図１６（Ａ）は実施例２および比較例の測定値のばらつきを示すグラフである。同一の押圧センサ５０を用いて繰り返し同様の押し込み荷重を付与した結果について説明する。比較例として第１増強板５１および第２増強板５２を用いずに測定した場合、押圧センサ５０の測定値のばらつきは概ね２４.５％であった。これに対して、第１増強板５１および第２増強板５２を用いて測定した場合、押圧センサ５０の測定値のばらつきは概ね２％であった。従って、第１増強板５１および第２増強板５２を用いた場合、第１増強板５１および第２増強板５２を用いなかった場合と比べて大幅に測定値のばらつきが抑制されることが確認された。 FIG. 16(A) is a graph showing variations in measured values of Example 2 and Comparative Example. The result of repeatedly applying the same pushing load using the same pressing sensor 50 will be described. As a comparative example, when the measurement was performed without using the first reinforcing plate 51 and the second reinforcing plate 52, the variation in the measured value of the pressure sensor 50 was about 24.5%. On the other hand, when the measurement was performed using the first enhancement plate 51 and the second enhancement plate 52, the variation in the measurement value of the pressure sensor 50 was approximately 2%. Therefore, it was confirmed that when the first and second intensifying plates 51 and 52 were used, the dispersion of the measured values was significantly suppressed as compared with the case where the first and second intensifying plates 51 and 52 were not used. Was done.
　以下、実施例３に係る保持測定機構６３について説明する。図１５（Ａ）および図１５（Ｂ）は、実施例３に係る押圧センサ５０の保持測定機構６３を示す図である。保持測定機構６３の説明においては、実施例２に係る保持測定機構６２と異なる点についてのみ説明を行い、同様の点については説明を省略する。 Hereinafter, the holding and measuring mechanism 63 according to the third embodiment will be described. 15(A) and 15(B) are views showing the holding and measuring mechanism 63 of the pressure sensor 50 according to the third embodiment. In the description of the holding and measuring mechanism 63, only the points different from the holding and measuring mechanism 62 according to the second embodiment will be described, and the description of the same points will be omitted.
　図１５（Ａ）および図１５（Ｂ）に示すように、保持測定機構６３は、保持測定機構６２から第１増強板５１を除いた構成である。すなわち、保持測定機構６３は、押圧センサ５０の一方側でのみ第２増強板５２によって支持される。第２増強板５２は、押圧センサ５０に対して押し込み荷重が加えられる押し子４１が当接される側と反対側にある。このように、押圧センサ５０の一方側でのみ第２増強板５２によって支持される場合であっても、第２増強板５２を用いない場合と比べて以下のように測定値のばらつきが抑制される。 As shown in FIGS. 15(A) and 15(B), the holding measurement mechanism 63 has a configuration in which the first enhancement plate 51 is removed from the holding measurement mechanism 62. That is, the holding measurement mechanism 63 is supported by the second enhancement plate 52 only on one side of the pressure sensor 50. The second intensifying plate 52 is on the side opposite to the side on which the pusher 41, to which a pushing load is applied, abuts the pressing sensor 50. As described above, even when the pressure sensor 50 is supported by the second intensifying plate 52 only on one side, compared to the case where the second intensifying plate 52 is not used, variations in measured values are suppressed as follows. It
　図１６（Ｂ）は実施例３および比較例の測定値のばらつきを示すグラフである。比較例として第２増強板５２を用いずに測定した場合、押圧センサ５０の測定値のばらつきは概ね２４.５％であった。これに対して、第２増強板５２を用いて測定した場合、押圧センサ５０の測定値のばらつきは概ね２．５％であった。従って、第２増強板５２を用いた場合、第２増強板５２を用いなかった場合と比べて大幅に測定値のばらつきが抑制されることが確認された。 FIG. 16(B) is a graph showing variations in measured values of Example 3 and Comparative Example. When the measurement was performed without using the second intensifying plate 52 as a comparative example, the variation in the measured values of the pressure sensor 50 was approximately 24.5%. On the other hand, when the measurement was performed using the second enhancement plate 52, the variation in the measurement value of the pressure sensor 50 was approximately 2.5%. Therefore, it was confirmed that when the second enhancement plate 52 was used, variations in the measured values were significantly suppressed as compared with the case where the second enhancement plate 52 was not used.
　以下、実施例４に係る保持測定機構６４について説明する。図１７（Ａ）および図１７（Ｂ）は、実施例４に係る押圧センサ６０の保持測定機構６４を示す図である。保持測定機構６４の説明においては、実施例２に係る保持測定機構６２と異なる点についてのみ説明を行い、同様の点については説明を省略する。 The holding and measuring mechanism 64 according to the fourth embodiment will be described below. 17(A) and 17(B) are diagrams showing the holding and measuring mechanism 64 of the pressure sensor 60 according to the fourth embodiment. In the description of the holding and measuring mechanism 64, only the points different from the holding and measuring mechanism 62 according to the second embodiment will be described, and the description of the same points will be omitted.
　図１７（Ａ）および図１７（Ｂ）に示すように、保持測定機構６４は、押圧センサ６０、プローブ７８、第３増強板７１、およびホルダ７０を備える。押圧センサ６０は、圧電フィルム３２、基材３３、および電気的接触部３５を備える。圧電フィルム３２および電気的接触部３５は、基材３３より第３増強板７１が配置されている側に配置されている。圧電フィルム３２は、ある程度張力をもって基材３３に貼り付けられている。このため、図１７（Ａ）に示すように、押圧センサ６０全体がＸ方向に突出するように反る場合がある。 As shown in FIGS. 17A and 17B, the holding and measuring mechanism 64 includes a pressure sensor 60, a probe 78, a third strengthening plate 71, and a holder 70. The pressure sensor 60 includes the piezoelectric film 32, the base material 33, and the electrical contact portion 35. The piezoelectric film 32 and the electrical contact portion 35 are arranged on the side where the third enhancement plate 71 is arranged with respect to the base material 33. The piezoelectric film 32 is attached to the base material 33 with some tension. Therefore, as shown in FIG. 17A, the entire pressure sensor 60 may warp so as to project in the X direction.
　プローブ７８は、ホルダ７０に対して－Ｘ方向側に配置されている。すなわち、プローブ７８は、電気的接触部３５に対して保持測定機構６２のプローブ３８とは逆の位置に配置されている。ホルダ７０および第３増強板７１は、プローブ７８と対応する位置に、孔７２を有する。プローブ７８がＸ方向に移動した場合、プローブ７８は、孔７２に挿入される。孔７２に挿入されたプローブ７８のＸ方向側は、電気的接触部３５に接触する。このように、押圧センサ６０又はプローブ７８等の配置が保持測定機構６２と異なる場合であっても、保持測定機構６２と同様に、測定することができる。 The probe 78 is arranged on the −X direction side with respect to the holder 70. That is, the probe 78 is arranged at a position opposite to the probe 38 of the holding and measuring mechanism 62 with respect to the electrical contact portion 35. The holder 70 and the third enhancement plate 71 have holes 72 at positions corresponding to the probes 78. When the probe 78 moves in the X direction, the probe 78 is inserted into the hole 72. The X direction side of the probe 78 inserted into the hole 72 contacts the electrical contact portion 35. As described above, even when the arrangement of the pressure sensor 60, the probe 78, or the like is different from that of the holding and measuring mechanism 62, the measurement can be performed similarly to the holding and measuring mechanism 62.
　最後に、前記実施形態の説明は、すべての点で例示であり、制限的なものではないと考えられるべきである。本発明の範囲は、上述の実施形態ではなく、特許請求の範囲によって示される。さらに、本発明の範囲は、特許請求の範囲と均等の範囲を含む。 Finally, the description of the above embodiments is to be considered as illustrative in all points and not restrictive. The scope of the invention is indicated by the claims rather than the embodiments described above. Further, the scope of the present invention includes the scope equivalent to the claims.
１０…圧電フィルム
２０，３０，５０，６０…押圧センサ
２１…補強材
２２…接合部材
２３…第１電極
２４，３３…基材
２５…第２電極
２６…第１接着層
２７，３２…圧電フィルム
２８…第２接着層
２９…第３電極
１０１…電子機器
１０２…筐体
１０３…表面パネル
１０４…表示部
１０５…粘着剤
１１１…回路基板
２００…センサ本体
３０４…ＳＵＳ
９０１…一軸延伸方向 10... Piezoelectric film 20, 30, 50, 60... Pressure sensor 21... Reinforcing material 22... Joining member 23... First electrode 24, 33... Base material 25... Second electrode 26... First adhesive layer 27, 32... Piezoelectric film 28... 2nd adhesive layer 29... 3rd electrode 101... Electronic device 102... Housing 103... Surface panel 104... Display part 105... Adhesive 111... Circuit board 200... Sensor body 304... SUS
901... Uniaxial stretching direction

Claims (7)

  1. 　補強材と、
    　接合部材と、
    　前記接合部材を介して前記補強材に接着されるセンサ本体と、
    　を備え、
    　前記補強材の弾性率は、５０ＧＰａ以上であり、
    　前記接合部材の弾性率は、０．１ＧＰａ以上である、
    　押圧センサ。     Reinforcements,
    A joining member,
    A sensor body bonded to the reinforcing member via the joining member,
    Equipped with
    The elastic modulus of the reinforcing material is 50 GPa or more,
    The elastic modulus of the joining member is 0.1 GPa or more,
    Pressure sensor.
  2. 　補強材と、
    　接合部材と、
    　前記接合部材を介して前記補強材に接着されるセンサ本体と、
    　を備え、
    　前記補強材、前記接合部材、および前記センサ本体の応力の中立面のうち前記センサ本体に最も近い中立面が、前記補強材または前記接合部材に存在する、
    　押圧センサ。     Reinforcements,
    A joining member,
    A sensor body bonded to the reinforcing member via the joining member,
    Equipped with
    Among the neutral surfaces of stress of the reinforcing material, the joining member, and the sensor body, the neutral surface closest to the sensor body is present in the reinforcing material or the joining member.
    Pressure sensor.
  3. 　前記センサ本体は、基準電極、圧電フィルム、およびシールド電極を備える、
    　請求項１または請求項２に記載の押圧センサ。     The sensor body includes a reference electrode, a piezoelectric film, and a shield electrode,
    The pressure sensor according to claim 1 or 2.
  4. 　前記接合部材は、半田を含む、
    　請求項１乃至請求項３のいずれか１項に記載の押圧センサ。     The joining member includes solder,
    The pressure sensor according to any one of claims 1 to 3.
  5. 　前記半田のフラックスが前記接合部材の周囲に配置されている、
    　請求項４に記載の押圧センサ。     The solder flux is arranged around the joining member,
    The pressure sensor according to claim 4.
  6. 　前記半田の内部に空間が形成されている、
    　請求項４または請求項５に記載の押圧センサ。     A space is formed inside the solder,
    The pressure sensor according to claim 4 or 5.
  7. 　請求項１乃至請求項６のいずれか１項に記載の押圧センサと、
    　前記押圧センサが配置される筐体と、
    　を備えた押圧検出装置。     A pressure sensor according to any one of claims 1 to 6;
    A casing in which the pressure sensor is arranged,
    A pressure detection device equipped with.
PCT/JP2019/037944 2018-12-20 2019-09-26 Pressure sensor and pressure detection device WO2020129346A1 (en)

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WO2015098724A1 (en) * 2013-12-24 2015-07-02 株式会社村田製作所 Piezoelectric-sensor production method
US20150242037A1 (en) * 2014-01-13 2015-08-27 Apple Inc. Transparent force sensor with strain relief
JP2015190863A (en) * 2014-03-28 2015-11-02 日本写真印刷株式会社 Pressure detector

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JP2011176187A (en) * 2010-02-25 2011-09-08 Kyocera Corp Laminated piezoelectric element, injection device and fuel injection system having the same
WO2015098724A1 (en) * 2013-12-24 2015-07-02 株式会社村田製作所 Piezoelectric-sensor production method
US20150242037A1 (en) * 2014-01-13 2015-08-27 Apple Inc. Transparent force sensor with strain relief
JP2015190863A (en) * 2014-03-28 2015-11-02 日本写真印刷株式会社 Pressure detector

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WO2022047738A1 (en) * 2020-09-04 2022-03-10 深圳纽迪瑞科技开发有限公司 Pressure sensing apparatus, and electronic device

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