WO2016059940A1 - Pressure detection device, pressure detection device control method, and program - Google Patents

Pressure detection device, pressure detection device control method, and program Download PDF

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Publication number
WO2016059940A1
WO2016059940A1 PCT/JP2015/076521 JP2015076521W WO2016059940A1 WO 2016059940 A1 WO2016059940 A1 WO 2016059940A1 JP 2015076521 W JP2015076521 W JP 2015076521W WO 2016059940 A1 WO2016059940 A1 WO 2016059940A1
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Prior art keywords
capacitance
voltage signal
unit
digital voltage
piezoelectric
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PCT/JP2015/076521
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French (fr)
Japanese (ja)
Inventor
栄二 角谷
心一 萩原
裕次 渡津
直人 井前
啓佑 尾▲崎▼
柴田　淳一
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日本写真印刷株式会社
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Publication of WO2016059940A1 publication Critical patent/WO2016059940A1/en

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    • 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

Definitions

  • the present invention relates to a pressure detection device, a control method for a pressure detection device, and a program using a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load.
  • Patent Document 1 discloses a transparent piezoelectric sensor including a transparent pressure-sensitive layer and a pair of transparent conductive film layers.
  • An object of the present invention is to enable accurate measurement of a pressing force in a pressure sensor.
  • a pressure detection device includes a pressure sensor, a touch detection unit, an integration circuit, a switch, an AD conversion unit, an acquisition unit, a switching unit, and a calculation unit.
  • the pressure sensor includes a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load.
  • the touch detection unit detects contact with the pressure sensor.
  • the integrating circuit includes an amplifier having an input portion connected to the piezoelectric sheet and a capacitance having one end connected to the input portion.
  • the switch can switch between a charged state and a discharged state of the capacitance.
  • the AD converter converts the analog voltage signal output from the integration circuit into a digital voltage signal.
  • An acquisition part acquires a digital voltage signal in the charge state of a capacitance.
  • the switching unit controls the switch to alternately repeat the charge state and the discharge state of the capacitance, and sets the capacitance to the discharge state for a predetermined time after the digital voltage signal is acquired.
  • the calculation unit calculates the pressing force measurement value by adding the acquired digital voltage signals while the touch detection unit detects contact with the pressure sensor.
  • the capacitance is alternately repeated between the charged state and the discharged state by the switching unit.
  • An acquisition part acquires a digital voltage signal in the charge state of a capacitance. Thereafter, the capacitance is discharged for a predetermined time.
  • the calculation unit calculates the pressing force measurement value by adding the acquired digital voltage signals while the touch detection unit detects contact with the pressure sensor. Therefore, the current pressing force value is obtained.
  • by repeatedly discharging the capacitance such a situation can be prevented even when the piezoelectric output exceeds the output limit of the integrating circuit, for example, due to the influence of noise.
  • the pressure detection device may further include a touch panel connected to the touch detection unit and a drive unit that drives the touch panel at a timing different from the timing of acquiring the digital voltage signal.
  • the touch panel is driven at a timing different from the timing at which the digital voltage signal is acquired. Therefore, the piezoelectric signal from the piezoelectric sheet is not easily affected by noise from the touch panel. That is, the digital voltage signal is not easily affected by noise from the touch panel.
  • the on-resistance R ( ⁇ ) of the switch and the capacitance C (F) of the capacitance may satisfy the following expression.
  • R ( ⁇ ) C (F) ⁇ 10 ms
  • the period in which the acquisition unit acquires the digital voltage signal may be 2% or more away from the commercial power supply frequency.
  • the digital voltage signal is not easily affected by AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic equipment or components.
  • the period in which the acquisition unit acquires the digital voltage signal may be irregular.
  • the digital voltage signal is not easily affected by AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic equipment or components.
  • a control method of a pressure detection device includes a pressure sensor having a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load, a touch detection unit that detects contact with the pressure sensor, and a piezoelectric device.
  • An integration circuit having an amplifier having an input connected to the sheet, a capacitance having one end connected to the input, a switch capable of switching between a charge state and a discharge state of the capacitance, and an analog voltage output from the integration circuit
  • a control method of a pressure detection device comprising: an AD conversion unit that converts a signal into a digital voltage signal. This method comprises the following steps.
  • ⁇ Acquisition step to acquire digital voltage signal in capacitance charge state ⁇ Switching step that switches the capacitance from the charged state to the discharged state after the digital voltage signal is acquired by controlling the switch, and maintains the discharged state for a predetermined time after switching.
  • the acquisition step a digital voltage signal is acquired in the charged state of the capacitance.
  • the switching step the capacitance is switched from the charged state to the discharged state, and the discharged state is maintained for a predetermined time.
  • the measured pressure value is calculated by adding the acquired digital voltage signals. Therefore, the current pressing force value is obtained.
  • by repeatedly discharging the capacitance such a situation can be prevented even when the piezoelectric output exceeds the output limit of the integrating circuit, for example, due to the influence of noise.
  • the control method may further include a driving step of driving the touch panel connected to the touch detection unit at a timing different from the timing for acquiring the digital voltage signal.
  • a program according to another aspect of the present invention is stored in a storage unit of a computer, and causes the computer to execute the control method of the pressure detection device.
  • the pressure applied to the piezoelectric sheet can be accurately measured by appropriately detecting the pressure applied to the piezoelectric sheet.
  • FIG. 1 is a schematic diagram of a pressure detection device according to a first embodiment.
  • the graph which shows the change of the piezoelectric output by the discharge of a capacitance.
  • the graph which shows the discharge timing of a capacitance, and the change of the piezoelectric output at the time of touch detection.
  • the graph which showed the change of the true pressing force, the change of the conventional piezoelectric output value, and the change of the piezoelectric output value of this embodiment.
  • the flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance 2nd Embodiment.
  • the flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance 3rd Embodiment.
  • the flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance 5th Embodiment).
  • Flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit (sixth embodiment). Schematic of an integrating circuit (seventh embodiment).
  • FIG. 1 is a schematic view of a pressure detection device according to the first embodiment of the present invention.
  • the pressure detection device 1 has a function of measuring a pressing load and a function of detecting contact with a pressure sensor.
  • the pressure detection device 1 mainly includes a pressure sensor 3, an integration circuit 5, a touch detection unit 7, a microcomputer 9, and a switch 11.
  • the pressure sensor 3 includes a piezoelectric sheet 21 and a touch panel 23.
  • the piezoelectric sheet 21 generates a piezoelectric signal corresponding to the applied load.
  • the integration circuit 5 converts the total amount of charges output from the piezoelectric sheet 21 into a voltage signal, that is, integrates and outputs the piezoelectric signal.
  • the output voltage signal is hereinafter referred to as “piezoelectric output”.
  • the integrating circuit 5 includes an operational amplifier 25 having an input part connected to the piezoelectric sheet, and a capacitance 27 having one end connected to the input part.
  • the touch detection unit 7 detects contact of the pressure sensor 3 with the touch panel 23.
  • the touch panel 23 is laminated with the piezoelectric sheet 21 and specifically has touch detection electrodes (not shown).
  • the microcomputer 9 includes a substrate and a CPU, RAM, ROM, and other electronic components mounted on the substrate.
  • the microcomputer 9 mainly includes a control unit 31, an AD conversion unit 39, and a switching unit 35.
  • the control unit 31 is a device for controlling other devices based on computer hardware and software including a CPU and a memory.
  • the control unit 31 includes an acquisition unit 36 and a calculation unit 37.
  • the acquisition unit 36 reads a digital voltage signal from the AD conversion unit 39.
  • the calculation unit 37 calculates the pressing force data by adding the acquired digital voltage signals while the touch detection unit 7 detects the contact with the pressure sensor 3.
  • the AD converter 39 converts the analog voltage signal output from the integration circuit into a digital voltage signal.
  • the switching unit 35 controls the switch to alternately repeat the charge state and the discharge state of the capacitance 27, and sets the capacitance 27 to the discharge state for a predetermined time after the digital voltage signal is acquired.
  • the switch 11 can switch between a charged state and a discharged state of the capacitance 27.
  • the functions of the above components will be described in detail later.
  • the piezoelectric sheet 21 is a sheet-like member, and a reference electrode (not shown) and a piezoelectric detection electrode (not shown) are formed on both surfaces. As a result, a piezoelectric signal corresponding to the load applied to the piezoelectric sheet 21 is generated between the detection electrode (not shown) and the reference electrode (not shown).
  • Examples of the material constituting the piezoelectric sheet 21 include a ceramic piezoelectric material, a fluoride polymer or a copolymer thereof, and a polymer material having chirality.
  • Examples of the ceramic piezoelectric material include barium titanate, lead titanate, lead zirconate titanate, potassium niobate, lithium niobate, and lithium tantalate.
  • Examples of the fluoride polymer or a copolymer thereof include polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, and vinylidene fluoride-trifluoroethylene copolymer.
  • Examples of the polymer material having chirality include L-type polylactic acid and R-type polylactic acid.
  • the piezoelectric sheet 21 may be a monomorph or a bimorph.
  • the piezoelectric detection electrode (not shown), the reference electrode (not shown), and the touch detection electrode (not shown) can be made of a conductive material.
  • the conductive material include transparent conductive oxides such as indium-tin oxide (ITO), tin-zinc oxide (Tin), polyethylene dioxythiophene A conductive polymer such as (Polyethylenedioxythiophene, PEDOT) can be used.
  • the electrode can be formed by using vapor deposition or screen printing.
  • a conductive metal such as copper or silver may be used as the conductive material.
  • the electrode may be formed by vapor deposition, or may be formed using a metal paste such as a copper paste or a silver paste.
  • a material having conductivity a material in which a conductive material such as carbon nanotube, metal particle, or metal nanofiber is dispersed in a binder may be used.
  • the touch detection unit 7 is a device that detects contact with the pressure sensor 3.
  • the touch detection electrode (not shown) of the touch panel 23 is formed so as to be electrically insulated from the piezoelectric detection electrode (not shown) of the piezoelectric sheet 21.
  • the touch detection part 7 can detect the touch detection signal which generate
  • the touch panel 23 includes a glass cover or a resin cover.
  • the self-capacitance or mutual capacitance of the touch detection electrode changes when the contact object contacts the main surface of the pressure sensor 3, and the change is detected by the touch detection unit 7.
  • Capacitance method By using the capacitance method, the touch detection unit 7 can reliably detect the contact between the finger and the pressure sensor 3 even when the force of the user's finger pressing the pressure sensor 3 is weak.
  • the touch detection part 7 the well-known electrostatic capacitance measuring apparatus used for the capacitive touch panel etc. can be used as the touch detection part 7, the well-known electrostatic capacitance measuring apparatus used for the capacitive touch panel etc. can be used.
  • the integrating circuit 5 has two inputs. One input is connected to a piezoelectric detection electrode (not shown) of the piezoelectric sheet 21, and the other input is connected to a reference electrode (not shown).
  • the operational amplifier 25 has two inputs. An input from the inverting input terminal marked with “ ⁇ ” of the operational amplifier 25 is connected to a piezoelectric detection electrode (not shown) formed on the piezoelectric sheet 21. On the other hand, the input from the non-inverting input terminal labeled “+” of the operational amplifier 25 is connected to a reference electrode (not shown) formed on the piezoelectric sheet 21 and a ground potential. In this case, when a piezoelectric signal having a positive potential difference is input between a piezoelectric detection electrode (not shown) and a reference electrode (not shown), the amplified piezoelectric signal having a negative potential difference is supplied from the operational amplifier 25. Is output (inverted amplification).
  • the operational amplifier 25 can output a signal that can determine the presence or absence of a signal even if the signal to the two inputs of the operational amplifier 25 is due to a slight charge. Therefore, by inputting a piezoelectric signal to the operational amplifier 25, it becomes possible to accurately measure the pressing force acting on the piezoelectric sheet 21 from a minute piezoelectric signal.
  • One end of the capacitance 27 is connected to the input of the operational amplifier 25 marked with “ ⁇ ”.
  • the other end of the capacitance 27 is connected to the output of the operational amplifier 25.
  • the operational amplifier 25 a known operational amplifier can be used.
  • the capacitance 27 a capacitor such as a film capacitor or a ceramic capacitor can be used. The capacity of the capacitor used as the capacitance 27 can be appropriately determined according to the intensity of the piezoelectric signal.
  • the microcomputer 9 includes a CPU (Central Processing Unit), a storage unit, an interface for driving the piezoelectric sensor, and the like. Note that the functions of the microcomputer may be integrated into one IC by a custom IC instead of the microcomputer.
  • CPU Central Processing Unit
  • storage unit for storing data
  • interface for driving the piezoelectric sensor and the like. Note that the functions of the microcomputer may be integrated into one IC by a custom IC instead of the microcomputer.
  • the control unit 31 controls the operation of the switching unit 35 according to the detection result of the touch detection unit 7.
  • the control unit 31 is connected to the touch detection unit 7 and the AD conversion unit 39.
  • the control part 31 can grasp
  • the switch 11 is connected in parallel with a capacitance 27 (described later) of the integrating circuit 5 and can switch between a charged state and a discharged state of the capacitance. Thereby, when the switch 11 is closed, the electric charge stored in the capacitance 27 can be discharged. Discharging is to store charges in the capacitance 27 by opening the switch 11 again after removing all the charges stored in the capacitance 27 by closing the switch 11.
  • the switch 11 When the switch 11 is closed and discharging is started, the electric charge stored in the capacitance 27 is discharged, the piezoelectric output decreases, and becomes zero when the discharge is completed. When the switch is opened, the electric charge is again accumulated in the capacitance 27, and the piezoelectric output increases.
  • a switching element that can input an external signal and can open and close a circuit based on the external signal can be used.
  • a semiconductor switch element using a switching characteristic of a semiconductor element such as an electromagnetic switch, an electromagnetic relay, or a field effect transistor (FET) can be used.
  • FIG. 3 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.
  • FIG. 4 is a flowchart for explaining pressing force data output control based on piezoelectric output addition in the touch detection period.
  • FIG. 5 is a graph showing the discharge timing of capacitance and the change in piezoelectric output at the time of touch detection. In the first state described below, the switch 11 is opened and the capacitance 27 is in a charged state.
  • step S ⁇ b> 1 the control unit 31 transmits a drive start signal to the touch detection unit 7.
  • the drive unit 29 of the touch detection unit 7 starts to drive the touch panel 23.
  • the driving is an operation for the touch panel 23 to detect a touch. For example, in the case of a capacitive touch panel or a resistive touch panel, an electrical signal is applied to an electrode (not shown) laid in the input area so that a touch can be detected.
  • step S ⁇ b> 2 thereafter, the drive unit 29 of the touch detection unit 7 stops driving the touch panel 23.
  • step S ⁇ b> 3 the acquisition unit 36 of the control unit 31 acquires the digital voltage signal from the detection unit 41. As described above, at this time, the capacitance 27 is in a charged state.
  • step S4 the control unit 31 opens and closes the switch 11 by transmitting a control signal to the switching unit 35, thereby causing the discharge process (the capacitance 27 is discharged for a predetermined time after the digital voltage signal is acquired). )I do. Specifically, the control unit 31 transmits a switch-on signal to the switching unit 35. Thereby, the switching unit 35 closes the switch 11. Thereby, the capacitance 27 is discharged. When a predetermined time has elapsed, the control unit 31 transmits a switch-off signal to the switching unit 35.
  • the switching unit 35 opens the switch 11. As a result, the capacitance 27 is charged. It should be noted that the time t 1 from the end of the piezoelectric output acquisition in step S3 to the start of discharge in step S4 is preferably as short as possible.
  • step S4 ends, the process returns to step S1.
  • a discharge operation is performed at a predetermined cycle, and the capacitance 27 is discharged each time.
  • touch panel drive ⁇ piezoelectric output acquisition ⁇ discharge is performed in this order, that is, touch panel drive and piezoelectric output acquisition are performed at different timings. Therefore, the piezoelectric signal of the piezoelectric sheet 21 is not easily affected by noise from the touch panel 23.
  • the touch panel drive cycle and the piezoelectric output acquisition and discharge cycle are constant.
  • step S ⁇ b> 5 the acquisition unit 36 of the control unit 31 always performs piezoelectric output acquisition regardless of whether or not there is a touch on the pressure sensor 3.
  • the acquired piezoelectric output includes the case where the piezoelectric signal is zero. If piezoelectric output acquisition is performed, the process proceeds to step S6.
  • step S6 If the touch is started (Yes in step S6, A in FIG. 5), the process proceeds to step S7. If there is no touch (No in step S6, C in FIG. 5), the process returns to step S5.
  • step S ⁇ b> 7 the calculation unit 37 adds the piezoelectric output values acquired by the acquisition unit 36. That is, after the touch is started, the calculation unit 37 repeats the addition until there is no touch (B in FIG. 5). However, the detection of the touch detection unit 7 may be delayed with respect to the actual touch. Therefore, the accuracy of the sequential addition of the calculation unit 37 is further improved by adding from the data that goes back for a certain time after the touch detection (D in FIG. 5).
  • step S8 the calculation unit 37 saves or outputs the added pressing force data to the outside. Thereafter, the process returns to step S5. That is, if there is a single touch, the pressing force data is acquired and then stored or output to the outside.
  • the touch detection unit 7 detects a touch (D in FIG. 5). Then, a touch detection signal is transmitted from the touch detection unit 7 to the control unit 31. Thereby, in the control part 31, the calculation part 37 adds the piezoelectric output acquired from the detection part 41 sequentially (B of FIG. 5). As a result, pressing force data is obtained. And the calculation part 37 preserve
  • the on-resistance R ( ⁇ ) of the switch 11 and the capacitance C (F) of the capacitance satisfy the following expression.
  • R ( ⁇ ) C (F) ⁇ 10 ms
  • the time required for discharging all the electric charges accumulated in the capacitance 27 after the switch 11 is closed is shortened.
  • the predetermined time for discharging the capacitance 27 can be set short. Note that the above conditions are not essential.
  • FIG. 6 is a graph showing changes in the true pressing force, changes in the conventional digital voltage signal, and changes in the digital voltage signal of the present embodiment.
  • true pressing force refers to a force pressing the touch panel with a finger or the like.
  • the piezoelectric output exceeds the output limit of, for example, the integration circuit 5 or the AD conversion unit 39 due to the influence of noise, so that the pressing force cannot be accurately detected.
  • the piezoelectric output By performing discharge control as in the present embodiment, it is possible to prevent the piezoelectric output from shaking off the output limit of the integration circuit 5 or the AD conversion unit 39, for example. Further, the digital voltage signal becomes zero by repeatedly discharging, but the current pressing force can be calculated by adding the acquired values. Note that when the touch is not detected (that is, there is no pressing), the value of the piezoelectric output is not added, that is, the pressing force is not calculated. Furthermore, although a noise component is superimposed on the pressing force, since the electric charge of the capacitance 27 is set to zero at every touch, the influence of the noise component does not occur.
  • FIG. 7 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.
  • the fundamental structure, function, and effect of each following embodiment are the same, in the following description, it demonstrates focusing on a different point.
  • step S21 is inserted before step S1.
  • the ratio of performing the touch panel drive for the piezoelectric output acquisition and the discharge can be set by setting the thinning number m.
  • FIG. 8 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.
  • step S21 is inserted between step S2 and step S3.
  • step S21 if the condition of the above equation is satisfied, the process proceeds to step S3. If the condition of the above equation is not satisfied, the process skips step S3 and step S4 (that is, piezoelectric output acquisition and discharge). The process proceeds to step S1.
  • step S1 In the above control, by setting the thinning-out number m, it is possible to set the ratio of performing the piezoelectric power acquisition and discharging with respect to the touch panel drive.
  • the repeated acquisition (reading) period of the piezoelectric output is a fixed period, but the embodiment of the present invention is not limited thereto. Rather, when the acquisition period is constant, AC noise having a period similar to that period may greatly affect the pressure detection. Therefore, for example, the piezoelectric output acquisition cycle is set to a cycle shifted from the AC noise cycle. In particular, since the influence of AC noise derived from commercial power supply frequency from fluorescent lamps, power supplies, other electronic devices and parts is large, the acquisition cycle of digital voltage signals should not be within 50Hz ⁇ 2% or within 60Hz ⁇ 2%. To do.
  • the period at which the calculation unit 37 acquires the piezoelectric output is 2% or more away from the commercial power supply frequency, the influence of the AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic devices or parts is small. Become.
  • FIG. 9 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.
  • step S22 is inserted between step S2 and step S3.
  • Step S22 is “WAIT”, which is a step of securing a delay time in a series of flows.
  • the influence of the AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic devices or parts is reduced by setting the acquisition period of the piezoelectric output to a period shifted from the AC noise period.
  • the method for reducing the influence of noise is not limited to the fourth embodiment.
  • the above effect may be realized by making the period in which the calculation unit 37 acquires the piezoelectric output irregular.
  • the first cycle is 10 ms
  • the second cycle is 11 ms
  • the third cycle is 9 ms
  • the fourth cycle is 12 ms
  • the fifth cycle is 12 ms
  • the sixth cycle is 7 ms.
  • FIG. 10 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.
  • step S23 is inserted between step S2 and step S3.
  • Step S23 is “Random WAIT” and is a step of securing an irregular delay time in a series of flows.
  • the period for obtaining the piezoelectric output is indefinite, but the period for driving the touch panel is also indefinite. In this case, it is difficult to take timing for devices that are susceptible to noise other than the integration circuit. Therefore, it is desirable to make the touch panel drive cycle constant while making the piezoelectric output acquisition cycle indefinite.
  • a delay time for adjustment is added to the control of the fifth embodiment in order to keep touch detection at a constant period.
  • FIG. 11 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.
  • step S24 is inserted after step S4.
  • Step S24 is “adjustment WAIT”, and is a step in which a delay time for keeping the touch detection constant is secured.
  • the touch driving cycle can be made constant.
  • the integrating circuit 5 including the operational amplifier 25 and the capacitance 27 is not limited to the configuration shown in FIG.
  • an integrating circuit 5A having a configuration of an operational amplifier 25 and a capacitance 27A as shown in FIG. 12 may be used.
  • FIG. 12 is a schematic diagram of the integration circuit.
  • an input with “+” of the operational amplifier 25 is connected to a piezoelectric detection electrode (not shown) of the piezoelectric sheet 21, and an input with “ ⁇ ” is connected via a resistor.
  • a reference electrode (not shown) is connected to a ground potential. The reference electrode is connected to the ground potential.
  • one end of the capacitance 27A is connected to the input with “+” of the operational amplifier 25, and the other end is connected to the ground potential.
  • the switch 11A is connected in parallel with the capacitance 27A and can switch between a charged state and a discharged state of the capacitance 27A. Specifically, one end of the switch 11A is connected to an input with “+” of the operational amplifier 25, and the other end is connected to the ground potential.
  • the capacitance 11 can be repeatedly discharged by controlling the discharge of the switch 11A.
  • the pressure detection device (for example, the pressure detection device 1) includes a pressure sensor, a touch detection unit, an integration circuit, a switch, an AD conversion unit, an acquisition unit, a switching unit, and a calculation unit.
  • the pressure sensor (for example, the pressure sensor 3) includes a piezoelectric sheet (for example, the piezoelectric sheet 21) that generates a piezoelectric signal corresponding to a given load.
  • the touch detection unit (for example, touch detection unit 7) detects contact with the pressure sensor.
  • the integration circuit (for example, the integration circuit 5) includes an amplifier having an input unit connected to the piezoelectric sheet and a capacitance having one end connected to the input unit.
  • the switch (for example, the switch 11) can switch between a charged state and a discharged state of the capacitance.
  • the AD conversion unit (for example, the AD conversion unit 39) converts an analog voltage signal output from the integration circuit into a digital voltage signal.
  • the acquisition unit (for example, the acquisition unit 36) acquires a digital voltage signal in a charged state of capacitance.
  • the switching unit controls the switch to alternately repeat the charge state and the discharge state of the capacitance, and sets the capacitance to the discharge state for a predetermined time after the digital voltage signal is acquired.
  • the calculation unit (for example, the calculation unit 37) calculates the pressing force measurement value by adding the acquired digital voltage signal while the touch detection unit detects contact with the pressure sensor.
  • the capacitance is alternately repeated between the charged state and the discharged state by the switching unit (see FIGS. 4 and 5).
  • the acquisition unit acquires a digital voltage signal in the charged state of the capacitance (for example, step S3 in FIG. 3). Thereafter, the capacitance is discharged for a predetermined time (for example, step S4 in FIG. 3).
  • the calculation unit calculates the pressing force measurement value by adding the acquired digital voltage signal while the touch detection unit detects contact with the pressure sensor (for example, step S7 in FIG. 4). Therefore, the current pressing force value is obtained. Further, by repeatedly discharging the capacitance, such a situation can be prevented even if the piezoelectric output exceeds the output limit of the integration circuit, for example, due to the influence of noise (see FIG. 6). ).
  • the touch panel of the pressure sensor is disposed so as to overlap the piezoelectric sheet, but the present invention is not limited to this.
  • the base material forming the touch detection electrode of the touch panel may also serve as the piezoelectric sheet.
  • the contact to the pressure sensor of the contact target object was detected with the electrostatic capacitance system.
  • the method for detecting contact of the contact object with the pressure sensor is not limited to the capacitance method.
  • the contact of the contact object with the pressure sensor may be detected by a method other than the capacitance method (for example, a resistance film method, an optical method, an ultrasonic method, etc.).
  • the present invention can be widely applied to a pressure detection device using a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load.
  • Pressure detector 3 Pressure sensor 5: Integration circuit 7: Touch detection unit 9: Microcomputer 11: Switch 21: Piezoelectric sheet 23: Touch panel 25: Operational amplifier 27: Capacitance 29: Drive unit 31: Control unit 35: Switching unit 36: Acquisition unit 37: calculation unit 39: AD converter

Abstract

[Problem] To make it possible to accurately measure a pressing force by means of a pressure sensor. [Solution] In a pressure detection device 1, a pressure sensor 3 has a piezoelectric sheet 21 that generates a piezoelectric signal corresponding to an applied load. A touch detection unit 7 detects a contact to the pressure sensor 3. A switch 11 is capable of performing switching between a charging state and a discharging state of a capacitance 27. An AD conversion unit 39 converts an analog voltage signal into a digital voltage signal, said analog voltage signal having been outputted from an integration circuit 5. An acquisition unit 36 acquires the digital voltage signal in the charging state of the capacitance 27. By controlling the switch 11, a switching unit 35 alternately repeats the charging state and the discharging state of the capacitance 27, and brings the capacitance 27 into the discharge state for a predetermined time after the digital voltage signal is acquired. During a time when the touch detection unit 7 is detecting the contact to the pressure sensor 3, a calculation unit 37 calculates a pressing force measurement value by adding an acquired digital voltage signal.

Description

圧力検出装置、圧力検出装置の制御方法、及びプログラムPressure detection device, control method of pressure detection device, and program

　本発明は、与えられた荷重に応じた圧電信号を発生する圧電シートを用いた、圧力検出装置、圧力検出装置の制御方法、及びプログラムに関する。
The present invention relates to a pressure detection device, a control method for a pressure detection device, and a program using a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load.

　例えばタッチパネルへの押圧量を検出するため、圧電シートを用いた圧力センサが知られている。例えば、特許文献１には、透明感圧層と、一対の透明導電膜層とからなる透明圧電センサが開示されている。
For example, a pressure sensor using a piezoelectric sheet is known to detect the amount of pressure on the touch panel. For example, Patent Document 1 discloses a transparent piezoelectric sensor including a transparent pressure-sensitive layer and a pair of transparent conductive film layers.

特開２００４－１２５５７１号公報JP 2004-125571 A

　特許文献１に開示された圧力センサにおいては、圧力センサの使用条件（特に、温度）の変化、又は周囲からの電気ノイズ（特に、静電気）に起因して、圧電信号にノイズ成分が重畳されることがある。この影響が大きい場合、検出された押圧力の出力信号がチャージアンプ又は増幅部の出力限界を超えてしまい、その超えた分の出力信号を検出できない。その結果、押圧力の値を正確に検出できなくなる。
In the pressure sensor disclosed in Patent Document 1, a noise component is superimposed on the piezoelectric signal due to a change in usage conditions (particularly temperature) of the pressure sensor or electrical noise (particularly static electricity) from the surroundings. Sometimes. When this influence is large, the output signal of the detected pressing force exceeds the output limit of the charge amplifier or the amplifying unit, and the output signal for the excess cannot be detected. As a result, the pressure value cannot be detected accurately.

　本発明の課題は、圧力センサにおいて押圧力を精度良く測定可能にすることにある。
An object of the present invention is to enable accurate measurement of a pressing force in a pressure sensor.

　以下に、課題を解決するための手段として複数の態様を説明する。これら態様は、必要に応じて任意に組み合せることができる。
Hereinafter, a plurality of modes will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary.

　本発明の一見地に係る圧力検出装置は、圧力センサと、タッチ検出部と、積分回路と、スイッチと、ＡＤ変換部と、取得部と、切替え部と、算出部とを備えている。

　圧力センサは、与えられた荷重に応じた圧電信号を発生する圧電シートを有する。

　タッチ検出部は、圧力センサへの接触を検出する。

　積分回路は、圧電シートに接続された入力部を有するアンプと、入力部に一端が接続されるキャパシタンスとを有する。

　スイッチは、キャパシタンスの充電状態と放電状態とを切替え可能である。

　ＡＤ変換部は、積分回路から出力されるアナログ電圧信号をデジタル電圧信号に変換する。

　取得部は、キャパシタンスの充電状態においてデジタル電圧信号を取得する。

　切替え部は、スイッチを制御することで、キャパシタンスの充電状態と放電状態とを交互に繰り返し、かつデジタル電圧信号が取得された後にキャパシタンスを所定時間だけ放電状態にする。

　算出部は、タッチ検出部が圧力センサへの接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力測定値を算出する。
A pressure detection device according to an aspect of the present invention includes a pressure sensor, a touch detection unit, an integration circuit, a switch, an AD conversion unit, an acquisition unit, a switching unit, and a calculation unit.

The pressure sensor includes a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load.

The touch detection unit detects contact with the pressure sensor.

The integrating circuit includes an amplifier having an input portion connected to the piezoelectric sheet and a capacitance having one end connected to the input portion.

The switch can switch between a charged state and a discharged state of the capacitance.

The AD converter converts the analog voltage signal output from the integration circuit into a digital voltage signal.

An acquisition part acquires a digital voltage signal in the charge state of a capacitance.

The switching unit controls the switch to alternately repeat the charge state and the discharge state of the capacitance, and sets the capacitance to the discharge state for a predetermined time after the digital voltage signal is acquired.

The calculation unit calculates the pressing force measurement value by adding the acquired digital voltage signals while the touch detection unit detects contact with the pressure sensor.

　この装置では、キャパシタンスは、切替え部によって充電状態と放電状態とを交互に繰り返される。取得部は、キャパシタンスの充電状態においてデジタル電圧信号を取得する。その後、キャパシタンスは所定時間だけ放電状態にされる。算出部は、タッチ検出部が圧力センサへの接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力測定値を算出する。したがって、現在の押圧力の値が得られる。

　また、キャパシタンスの放電を繰り返して行うことで、従来であればノイズの影響で圧電出力が例えば積分回路の出力限界を超えてしまうような場合でも、そのような事態を防止できる。
In this device, the capacitance is alternately repeated between the charged state and the discharged state by the switching unit. An acquisition part acquires a digital voltage signal in the charge state of a capacitance. Thereafter, the capacitance is discharged for a predetermined time. The calculation unit calculates the pressing force measurement value by adding the acquired digital voltage signals while the touch detection unit detects contact with the pressure sensor. Therefore, the current pressing force value is obtained.

In addition, by repeatedly discharging the capacitance, such a situation can be prevented even when the piezoelectric output exceeds the output limit of the integrating circuit, for example, due to the influence of noise.

　圧力検出装置は、タッチ検出部に接続されたたタッチパネルと、デジタル電圧信号を取得するタイミングとは異なるタイミングで、タッチパネルを駆動する駆動部と、をさらに備えていてもよい。

　この装置では、タッチパネルは、デジタル電圧信号が取得されるタイミングと異なるタイミングで駆動させられる。したがって、圧電シートからの圧電信号がタッチパネルからのノイズによる影響を受けにくい。つまり、デジタル電圧信号がタッチパネルからのノイズによる影響を受けにくい。
The pressure detection device may further include a touch panel connected to the touch detection unit and a drive unit that drives the touch panel at a timing different from the timing of acquiring the digital voltage signal.

In this apparatus, the touch panel is driven at a timing different from the timing at which the digital voltage signal is acquired. Therefore, the piezoelectric signal from the piezoelectric sheet is not easily affected by noise from the touch panel. That is, the digital voltage signal is not easily affected by noise from the touch panel.

　スイッチのオン抵抗Ｒ（Ω）とキャパシタンスの容量Ｃ（Ｆ）が以下の式を満たしてもよい。

　Ｒ（Ω）Ｃ（Ｆ）＜１０ｍｓ

　この装置では、上記の式が満たされることで、スイッチを閉じてからキャパシタンスに貯まった電荷がすべて放電されるのに要する時間が短くなる。
The on-resistance R (Ω) of the switch and the capacitance C (F) of the capacitance may satisfy the following expression.

R (Ω) C (F) <10 ms

In this apparatus, when the above equation is satisfied, the time required for discharging all the electric charge accumulated in the capacitance after closing the switch is shortened.

　取得部がデジタル電圧信号を取得する周期が、商用電源周波数から２％以上離れていてもよい。

　この結果、デジタル電圧信号が、蛍光灯、電源又はその他電子機器若しくは部品からの商用電源周波数由来の交流ノイズの影響を受けにくくなる。
The period in which the acquisition unit acquires the digital voltage signal may be 2% or more away from the commercial power supply frequency.

As a result, the digital voltage signal is not easily affected by AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic equipment or components.

　取得部がデジタル電圧信号を取得する周期が不定期であってもよい。

　この結果、デジタル電圧信号が、蛍光灯、電源又はその他電子機器若しくは部品からの商用電源周波数由来の交流ノイズの影響を受けにくくなる。
The period in which the acquisition unit acquires the digital voltage signal may be irregular.

As a result, the digital voltage signal is not easily affected by AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic equipment or components.

　本発明の他の見地に係る圧力検出装置の制御方法は、与えられた荷重に応じた圧電信号を発生する圧電シートを有する圧力センサと、圧力センサへの接触を検出するタッチ検出部と、圧電シートに接続された入力部を有するアンプと入力部に一端が接続されるキャパシタンスとを有する積分回路と、キャパシタンスの充電状態と放電状態とを切替え可能なスイッチと、積分回路から出力されるアナログ電圧信号をデジタル電圧信号に変換するＡＤ変換部と、を備えた圧力検出装置の制御方法である。この方法は、下記のステップを備えている。

　◎キャパシタンスの充電状態においてデジタル電圧信号を取得する取得ステップ

　◎スイッチを制御することで、デジタル電圧信号が取得された後にキャパシタンスを充電状態から放電状態に切替え、切替え後所定時間だけ放電状態を維持する切替えステップ

　タッチ検出部が圧力センサへの接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力測定値を算出する算出ステップ

　この装置では、取得ステップでは、キャパシタンスの充電状態においてデジタル電圧信号が取得される。その後、切替えステップでは、キャパシタンスは充電状態から放電状態に切り替えられ、所定時間だけ放電状態を維持される。算出ステップでは、タッチ検出部が圧力センサへの接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力測定値を算出する。したがって、現在の押圧力の値が得られる。

　また、キャパシタンスの放電を繰り返して行うことで、従来であればノイズの影響で圧電出力が例えば積分回路の出力限界を超えてしまうような場合でも、そのような事態を防止できる。
A control method of a pressure detection device according to another aspect of the present invention includes a pressure sensor having a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load, a touch detection unit that detects contact with the pressure sensor, and a piezoelectric device. An integration circuit having an amplifier having an input connected to the sheet, a capacitance having one end connected to the input, a switch capable of switching between a charge state and a discharge state of the capacitance, and an analog voltage output from the integration circuit A control method of a pressure detection device comprising: an AD conversion unit that converts a signal into a digital voltage signal. This method comprises the following steps.

◎ Acquisition step to acquire digital voltage signal in capacitance charge state

◎ Switching step that switches the capacitance from the charged state to the discharged state after the digital voltage signal is acquired by controlling the switch, and maintains the discharged state for a predetermined time after switching.

Calculation step for calculating the pressing force measurement value by adding the acquired digital voltage signal while the touch detection unit detects contact with the pressure sensor.

In this device, in the acquisition step, a digital voltage signal is acquired in the charged state of the capacitance. Thereafter, in the switching step, the capacitance is switched from the charged state to the discharged state, and the discharged state is maintained for a predetermined time. In the calculation step, while the touch detection unit detects contact with the pressure sensor, the measured pressure value is calculated by adding the acquired digital voltage signals. Therefore, the current pressing force value is obtained.

In addition, by repeatedly discharging the capacitance, such a situation can be prevented even when the piezoelectric output exceeds the output limit of the integrating circuit, for example, due to the influence of noise.

　制御方法は、デジタル電圧信号を取得するタイミングとは異なるタイミングで、タッチ検出部に接続されたタッチパネルを駆動する駆動ステップを、さらに備えていてもよい。
The control method may further include a driving step of driving the touch panel connected to the touch detection unit at a timing different from the timing for acquiring the digital voltage signal.

　本発明の他の見地に係るプログラムは、コンピュータの記憶部に保存され、上記の圧力検出装置の制御方法をコンピュータに実行させる。
A program according to another aspect of the present invention is stored in a storage unit of a computer, and causes the computer to execute the control method of the pressure detection device.

　本発明に係る圧力検出装置では、圧電シートへの押圧を適切に検出することで、圧電シートへの押圧力を精度良く測定できる。
In the pressure detection device according to the present invention, the pressure applied to the piezoelectric sheet can be accurately measured by appropriately detecting the pressure applied to the piezoelectric sheet.

第１実施形態に係る圧力検出装置の概略図。1 is a schematic diagram of a pressure detection device according to a first embodiment. キャパシタンスの放電による圧電出力の変化を示すグラフ。The graph which shows the change of the piezoelectric output by the discharge of a capacitance. 制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャート。The flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance. タッチ検出期間における圧電出力加算による押圧力データ出力制御を説明するためのフローチャート。The flowchart for demonstrating the pressing force data output control by the piezoelectric output addition in a touch detection period. キャパシタンスの放電タイミングとタッチ検出時の圧電出力の変化を示すグラフ。The graph which shows the discharge timing of a capacitance, and the change of the piezoelectric output at the time of touch detection. 真の押圧力の変化、従来での圧電出力値の変化、本実施形態の圧電出力値の変化を示したグラフ。The graph which showed the change of the true pressing force, the change of the conventional piezoelectric output value, and the change of the piezoelectric output value of this embodiment. 制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャート（第２実施形態）。The flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance (2nd Embodiment). 制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャート（第３実施形態）。The flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance (3rd Embodiment). 制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャート（第４実施形態）。The flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance (4th Embodiment). 制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャート（第５実施形態）。The flowchart for demonstrating the touch panel drive by a control part, piezoelectric output acquisition, and the discharge control of a capacitance (5th Embodiment). 制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャート（第６実施形態）。Flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit (sixth embodiment). 積分回路の概略図（第７実施形態）。Schematic of an integrating circuit (seventh embodiment).

１．第１実施形態

（１）圧力検出装置の全体構造

　まず、本発明の第１実施形態に係る圧力検出装置１の全体構造について図１を用いて説明する。図１は、本発明の第１実施形態に係る圧力検出装置の概略図である。

　圧力検出装置１は、押圧荷重を測定する機能と、圧力センサへの接触を検出する機能とを有している。
1. First embodiment

(1) Overall structure of pressure detector

First, the overall structure of the pressure detection device 1 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic view of a pressure detection device according to the first embodiment of the present invention.

The pressure detection device 1 has a function of measuring a pressing load and a function of detecting contact with a pressure sensor.
　圧力検出装置１は、主に、圧力センサ３と、積分回路５と、タッチ検出部７と、マイコン９と、スイッチ１１とを有する。

　圧力センサ３は、圧電シート２１と、タッチパネル２３とを有する。圧電シート２１は、与えられた荷重に応じた圧電信号を発生する。
The pressure detection device 1 mainly includes a pressure sensor 3, an integration circuit 5, a touch detection unit 7, a microcomputer 9, and a switch 11.

The pressure sensor 3 includes a piezoelectric sheet 21 and a touch panel 23. The piezoelectric sheet 21 generates a piezoelectric signal corresponding to the applied load.

　積分回路５は、圧電シート２１からの出力される電荷の総量を電圧信号に変換する、つまり圧電信号を積分して出力する。出力される電圧信号を以下「圧電出力」という。これにより、圧電シート２１の押圧力の変化量に起因して発生する微小な圧電信号から、精度良く圧電シート２１の押圧力を測定できる。積分回路５は、圧電シートに接続された入力部を有するオペアンプ２５と、入力部に一端が接続されるキャパシタンス２７とを有する。

　タッチ検出部７は、圧力センサ３のタッチパネル２３への接触を検出する。タッチパネル２３は、圧電シート２１と積層されており、具体的にはタッチ検出電極（図示せず）を有している。
The integration circuit 5 converts the total amount of charges output from the piezoelectric sheet 21 into a voltage signal, that is, integrates and outputs the piezoelectric signal. The output voltage signal is hereinafter referred to as “piezoelectric output”. As a result, the pressing force of the piezoelectric sheet 21 can be accurately measured from a minute piezoelectric signal generated due to the amount of change in the pressing force of the piezoelectric sheet 21. The integrating circuit 5 includes an operational amplifier 25 having an input part connected to the piezoelectric sheet, and a capacitance 27 having one end connected to the input part.

The touch detection unit 7 detects contact of the pressure sensor 3 with the touch panel 23. The touch panel 23 is laminated with the piezoelectric sheet 21 and specifically has touch detection electrodes (not shown).

　マイコン９は、図示しないが、基板と、基板に搭載されたＣＰＵ、ＲＡＭ、ＲＯＭ、その他電子部品とを有する。マイコン９は、主に、制御部３１と、ＡＤ変換部３９と、切替え部３５とを有している。

　制御部３１は、ＣＰＵ及びメモリからなるコンピュータのハードウェアとソフトウェアに基づいて、他の装置を制御するための装置である。制御部３１は、取得部３６と、算出部３７とを有している。

　取得部３６は、ＡＤ変換部３９からデジタル電圧信号を読み込む。

　算出部３７は、タッチ検出部７が圧力センサ３への接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力データを算出する。
Although not shown, the microcomputer 9 includes a substrate and a CPU, RAM, ROM, and other electronic components mounted on the substrate. The microcomputer 9 mainly includes a control unit 31, an AD conversion unit 39, and a switching unit 35.

The control unit 31 is a device for controlling other devices based on computer hardware and software including a CPU and a memory. The control unit 31 includes an acquisition unit 36 and a calculation unit 37.

The acquisition unit 36 reads a digital voltage signal from the AD conversion unit 39.

The calculation unit 37 calculates the pressing force data by adding the acquired digital voltage signals while the touch detection unit 7 detects the contact with the pressure sensor 3.

　ＡＤ変換部３９は、積分回路から出力されるアナログ電圧信号をデジタル電圧信号に変換する。

　切替え部３５は、スイッチを制御することで、キャパシタンス２７の充電状態と放電状態とを交互に繰り返し、かつデジタル電圧信号が取得された後にキャパシタンス２７を所定時間だけ放電状態にする。
The AD converter 39 converts the analog voltage signal output from the integration circuit into a digital voltage signal.

The switching unit 35 controls the switch to alternately repeat the charge state and the discharge state of the capacitance 27, and sets the capacitance 27 to the discharge state for a predetermined time after the digital voltage signal is acquired.

　スイッチ１１は、キャパシタンス２７の充電状態と放電状態とを切替え可能である。

　上記の各構成の機能は、後にさらに詳細に説明する。
The switch 11 can switch between a charged state and a discharged state of the capacitance 27.

The functions of the above components will be described in detail later.

（２）圧電シート

　圧電シート２１は、シート状の部材であり、両面に基準電極（図示せず）及び圧電検出電極（図示せず）が形成されている。その結果、検出電極（図示せず）と基準電極（図示せず）との間には、圧電シート２１に与えられた荷重に応じた圧電信号が発生する。
(2) Piezoelectric sheet

The piezoelectric sheet 21 is a sheet-like member, and a reference electrode (not shown) and a piezoelectric detection electrode (not shown) are formed on both surfaces. As a result, a piezoelectric signal corresponding to the load applied to the piezoelectric sheet 21 is generated between the detection electrode (not shown) and the reference electrode (not shown).

　圧電シート２１を構成する材料としては、セラミック圧電材料、フッ化物重合体又はその共重合体、キラリティーを有する高分子材料などが挙げられる。セラミック圧電材料としては、チタン酸バリウム、チタン酸鉛、チタン酸ジルコン酸鉛、ニオブ酸カリウム、ニオブ酸リチウム、タンタル酸リチウムなどが挙げられる。フッ化物重合体又はその共重合体としては、ポリフッ化ビニリデン、フッ化ビニリデン－テトラフルオロエチレン共重合体、フッ化ビニリデン－トリフルオロエチレン共重合体などが挙げられる。キラリティーを有する高分子材料としては、Ｌ型ポリ乳酸や、Ｒ型ポリ乳酸などが挙げられる。

　圧電シート２１は、モノモルフでもよいし、バイモルフでもよい。
Examples of the material constituting the piezoelectric sheet 21 include a ceramic piezoelectric material, a fluoride polymer or a copolymer thereof, and a polymer material having chirality. Examples of the ceramic piezoelectric material include barium titanate, lead titanate, lead zirconate titanate, potassium niobate, lithium niobate, and lithium tantalate. Examples of the fluoride polymer or a copolymer thereof include polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, and vinylidene fluoride-trifluoroethylene copolymer. Examples of the polymer material having chirality include L-type polylactic acid and R-type polylactic acid.

The piezoelectric sheet 21 may be a monomorph or a bimorph.

（３）電極

　圧電検出電極（図示せず）、基準電極（図示せず）、及びタッチ検出電極（図示せず）は、導電性を有する材料により構成できる。導電性を有する材料としては、インジウム－スズ酸化物（Ｉｎｄｉｕｍ－Ｔｉｎ－Ｏｘｉｄｅ、ＩＴＯ）、スズ－亜鉛酸化物（Ｔｉｎ－Ｚｉｎｃ－Ｏｘｉｄｅ、ＴＺＯ）などのような透明導電酸化物、ポリエチレンジオキシチオフェン（Ｐｏｌｙｅｔｈｙｌｅｎｅｄｉｏｘｙｔｈｉｏｐｈｅｎｅ、ＰＥＤＯＴ）などの導電性高分子、などを用いることができる。この場合、上記の電極は、蒸着やスクリーン印刷などを用いて形成できる。
(3) Electrode

The piezoelectric detection electrode (not shown), the reference electrode (not shown), and the touch detection electrode (not shown) can be made of a conductive material. Examples of the conductive material include transparent conductive oxides such as indium-tin oxide (ITO), tin-zinc oxide (Tin), polyethylene dioxythiophene A conductive polymer such as (Polyethylenedioxythiophene, PEDOT) can be used. In this case, the electrode can be formed by using vapor deposition or screen printing.

　また、導電性を有する材料として、銅、銀などの導電性の金属を用いてもよい。この場合、上記の電極は、蒸着により形成してもよく、銅ペースト、銀ペーストなどの金属ペーストを用いて形成してもよい。

　さらに、導電性を有する材料として、バインダー中に、カーボンナノチューブ、金属粒子、金属ナノファイバーなどの導電材料が分散したものを用いてもよい。
Alternatively, a conductive metal such as copper or silver may be used as the conductive material. In this case, the electrode may be formed by vapor deposition, or may be formed using a metal paste such as a copper paste or a silver paste.

Furthermore, as a material having conductivity, a material in which a conductive material such as carbon nanotube, metal particle, or metal nanofiber is dispersed in a binder may be used.

（４）タッチ検出部

　タッチ検出部７は、圧力センサ３への接触を検出する装置である。この実施形態では、タッチパネル２３のタッチ検出電極（図示せず）は、圧電シート２１の圧電検出電極（図示せず）とは電気的に絶縁されるように形成されている。これにより、タッチ検出部７は、ユーザの指などの接触対象物が圧力センサ３の主面に接触した際に発生するタッチ検出信号を、タッチ検出電極（図示せず）を介して、検出できる。なお、タッチパネル２３は、ガラスカバー又は樹脂製カバーを含んでいる。
(4) Touch detector

The touch detection unit 7 is a device that detects contact with the pressure sensor 3. In this embodiment, the touch detection electrode (not shown) of the touch panel 23 is formed so as to be electrically insulated from the piezoelectric detection electrode (not shown) of the piezoelectric sheet 21. Thereby, the touch detection part 7 can detect the touch detection signal which generate | occur | produces when contact objects, such as a user's finger | toe, contact the main surface of the pressure sensor 3 via a touch detection electrode (not shown). . The touch panel 23 includes a glass cover or a resin cover.

　この圧力センサ３では、接触対象物が圧力センサ３の主面に接触したときにタッチ検出電極（図示せず）の自己容量又は相互容量が変化し、その変化が、タッチ検出部７にて検出される（静電容量方式）。静電容量方式を用いることで、タッチ検出部７は、ユーザの指が圧力センサ３を押圧する力が弱い場合でも、確実に指と圧力センサ３との接触を検出できる。

　なお、タッチ検出部７としては、静電容量方式のタッチパネルなどに用いられている、公知の静電容量測定装置を用いることができる。
In this pressure sensor 3, the self-capacitance or mutual capacitance of the touch detection electrode (not shown) changes when the contact object contacts the main surface of the pressure sensor 3, and the change is detected by the touch detection unit 7. (Capacitance method). By using the capacitance method, the touch detection unit 7 can reliably detect the contact between the finger and the pressure sensor 3 even when the force of the user's finger pressing the pressure sensor 3 is weak.

In addition, as the touch detection part 7, the well-known electrostatic capacitance measuring apparatus used for the capacitive touch panel etc. can be used.

（５）積分回路

　積分回路５は、２つの入力を有している。１つの入力は圧電シート２１の圧電検出電極（図示せず）と接続され、もう１つの入力は基準電極（図示せず）に接続されている。
(5) Integration circuit

The integrating circuit 5 has two inputs. One input is connected to a piezoelectric detection electrode (not shown) of the piezoelectric sheet 21, and the other input is connected to a reference electrode (not shown).

　オペアンプ２５は、２つの入力を有している。オペアンプ２５の「－」を付した反転入力端子からの入力は、圧電シート２１に形成された圧電検出電極（図示せず）へ接続されている。一方、オペアンプ２５の「＋」を付した非反転入力端子からの入力は、圧電シート２１に形成された基準電極（図示せず）及びグランド電位に接続されている。この場合、圧電検出電極（図示せず）と基準電極（図示せず）との間に正の電位差を有した圧電信号が入力されると、オペアンプ２５から負の電位差を有する増幅された圧電信号が出力される（反転増幅）。
The operational amplifier 25 has two inputs. An input from the inverting input terminal marked with “−” of the operational amplifier 25 is connected to a piezoelectric detection electrode (not shown) formed on the piezoelectric sheet 21. On the other hand, the input from the non-inverting input terminal labeled “+” of the operational amplifier 25 is connected to a reference electrode (not shown) formed on the piezoelectric sheet 21 and a ground potential. In this case, when a piezoelectric signal having a positive potential difference is input between a piezoelectric detection electrode (not shown) and a reference electrode (not shown), the amplified piezoelectric signal having a negative potential difference is supplied from the operational amplifier 25. Is output (inverted amplification).

　オペアンプ２５は、オペアンプ２５の２つの入力への信号がわずかな電荷によるものである場合でも、信号の有無を判別可能な程度の信号を出力できる。そのため、オペアンプ２５に圧電信号を入力することにより、微小な圧電信号から、精度良く圧電シート２１に作用する押圧力を測定できるようになる。
The operational amplifier 25 can output a signal that can determine the presence or absence of a signal even if the signal to the two inputs of the operational amplifier 25 is due to a slight charge. Therefore, by inputting a piezoelectric signal to the operational amplifier 25, it becomes possible to accurately measure the pressing force acting on the piezoelectric sheet 21 from a minute piezoelectric signal.

　キャパシタンス２７は、その一端が、「－」を付したオペアンプ２５の入力に接続されている。また、キャパシタンス２７の他端が、オペアンプ２５の出力に接続されている。

　このようにして、圧電シート２１の押圧力の変化量に起因して発生する電圧信号を積分して、オペアンプ２５から増幅された圧電信号を出力できる。
One end of the capacitance 27 is connected to the input of the operational amplifier 25 marked with “−”. The other end of the capacitance 27 is connected to the output of the operational amplifier 25.

In this way, the voltage signal generated due to the amount of change in the pressing force of the piezoelectric sheet 21 can be integrated and the amplified piezoelectric signal from the operational amplifier 25 can be output.

　なお、オペアンプ２５としては、公知のオペアンプを用いることができる。また、キャパシタンス２７としては、フィルムコンデンサ、セラミックコンデンサなどのコンデンサを用いることができる。キャパシタンス２７として用いるコンデンサの容量は、圧電信号の強度などに応じて、適宜決定できる。
As the operational amplifier 25, a known operational amplifier can be used. Further, as the capacitance 27, a capacitor such as a film capacitor or a ceramic capacitor can be used. The capacity of the capacitor used as the capacitance 27 can be appropriately determined according to the intensity of the piezoelectric signal.

（６）マイコン

　マイコン９は、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ）、記憶部、及び圧電センサを駆動するためのインターフェースなどを備えている。なお、マイコンの代わりに、カスタムＩＣなどにより１つのＩＣにマイコンの機能が集約されていてもよい。
(6) Microcomputer

The microcomputer 9 includes a CPU (Central Processing Unit), a storage unit, an interface for driving the piezoelectric sensor, and the like. Note that the functions of the microcomputer may be integrated into one IC by a custom IC instead of the microcomputer.

　制御部３１は、タッチ検出部７の検出結果に応じて、切替え部３５の動作を制御する。そのために、制御部３１は、タッチ検出部７とＡＤ変換部３９に接続されている。制御部３１は、タッチ検出部７がタッチ検出信号の検出に基づいて出力する信号（タッチ信号）が入力されることで、タッチ検出部７がタッチ検出信号を検出したことを把握できる。そして、制御部３１は、切替え部３５に対して、スイッチ１１のオンオフを指令する信号を出力する。
The control unit 31 controls the operation of the switching unit 35 according to the detection result of the touch detection unit 7. For this purpose, the control unit 31 is connected to the touch detection unit 7 and the AD conversion unit 39. The control part 31 can grasp | ascertain that the touch detection part 7 detected the touch detection signal by the signal (touch signal) which the touch detection part 7 outputs based on the detection of a touch detection signal being input. Then, the control unit 31 outputs a signal instructing the switch 11 to turn on and off the switch 11.

（７）スイッチ

　スイッチ１１は、積分回路５のキャパシタンス２７（後述）と並列に接続されており、キャパシタンスの充電状態と放電状態とを切替え可能である。これにより、スイッチ１１が閉状態になったときに、キャパシタンス２７に貯まった電荷をディスチャージできる。ディスチャージとは、スイッチ１１を閉じることでキャパシタンス２７に貯まった電荷をすべて取り除いた後に、スイッチ１１をまた開けることでキャパシタンス２７に電荷を貯めることである。
(7) Switch

The switch 11 is connected in parallel with a capacitance 27 (described later) of the integrating circuit 5 and can switch between a charged state and a discharged state of the capacitance. Thereby, when the switch 11 is closed, the electric charge stored in the capacitance 27 can be discharged. Discharging is to store charges in the capacitance 27 by opening the switch 11 again after removing all the charges stored in the capacitance 27 by closing the switch 11.

　図２を用いて、ディスチャージを説明する。スイッチ１１を閉じてディスチャージを開始すると、キャパシタンス２７に貯まっていた電荷が放電され、圧電出力は下がっていき、放電しきるとゼロになる。スイッチを開くと、再びキャパシタンス２７に電荷がたまっていき、圧電出力は上がっていく。

　スイッチ１１としては、外部信号が入力可能で、当該外部信号に基づき回路の開閉が可能となるスイッチング素子を用いることができる。このようなスイッチング素子としては、電磁スイッチ又は電磁リレー、電界効果トランジスタ（Ｆｉｅｌｄ　Ｅｆｆｅｃｔ　Ｔｒａｎｓｉｓｔｏｒ、ＦＥＴ）などの半導体素子のスイッチング特性を利用した半導体スイッチ素子、などを用いることができる。
The discharge will be described with reference to FIG. When the switch 11 is closed and discharging is started, the electric charge stored in the capacitance 27 is discharged, the piezoelectric output decreases, and becomes zero when the discharge is completed. When the switch is opened, the electric charge is again accumulated in the capacitance 27, and the piezoelectric output increases.

As the switch 11, a switching element that can input an external signal and can open and close a circuit based on the external signal can be used. As such a switching element, a semiconductor switch element using a switching characteristic of a semiconductor element such as an electromagnetic switch, an electromagnetic relay, or a field effect transistor (FET) can be used.

（８）制御動作

　図３～図５を用いて、制御部３１のタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明する。図３は、制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャートである。図４は、タッチ検出期間における圧電出力加算による押圧力データ出力制御を説明するためのフローチャートである。図５は、キャパシタンスの放電タイミングとタッチ検出時の圧電出力の変化を示すグラフである。

　なお、下記の説明の最初の状態では、スイッチ１１は開けられており、キャパシタンス２７は充電状態である。
(8) Control action

The touch panel drive, piezoelectric output acquisition, and capacitance discharge control of the control unit 31 will be described with reference to FIGS. FIG. 3 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit. FIG. 4 is a flowchart for explaining pressing force data output control based on piezoelectric output addition in the touch detection period. FIG. 5 is a graph showing the discharge timing of capacitance and the change in piezoelectric output at the time of touch detection.

In the first state described below, the switch 11 is opened and the capacitance 27 is in a charged state.

　ステップＳ１では、制御部３１は、タッチ検出部７に駆動開始信号を送信する。これにより、タッチ検出部７の駆動部２９は、タッチパネル２３の駆動を開始する。ここでの駆動とは、タッチパネル２３がタッチを検出するための動作のことである。例えば、静電容量方式や抵抗膜方式のタッチパネルの場合は、入力エリアに敷設された電極（図示せず）に電気信号を与え、タッチを検出可能にする。

　ステップＳ２では、その後、タッチ検出部７の駆動部２９は、タッチパネル２３の駆動を停止する。
In step S <b> 1, the control unit 31 transmits a drive start signal to the touch detection unit 7. Thereby, the drive unit 29 of the touch detection unit 7 starts to drive the touch panel 23. The driving here is an operation for the touch panel 23 to detect a touch. For example, in the case of a capacitive touch panel or a resistive touch panel, an electrical signal is applied to an electrode (not shown) laid in the input area so that a touch can be detected.

In step S <b> 2, thereafter, the drive unit 29 of the touch detection unit 7 stops driving the touch panel 23.

　ステップＳ３では、制御部３１の取得部３６は、検出部４１からのデジタル電圧信号を取得する。前述のように、このとき、キャパシタンス２７は充電状態である。

　ステップＳ４では、制御部３１は、切替え部３５に制御信号を送信することで、スイッチ１１を開閉させ、それによりディスチャージ処理（デジタル電圧信号が取得された後にキャパシタンス２７を所定時間だけ放電状態にする）を行う。具体的には、制御部３１は、切替え部３５にスイッチオン信号を送信する。それにより、切替え部３５は、スイッチ１１を閉じる。これにより、キャパシタンス２７が放電される。そして、所定時間が経過すると、制御部３１は、切替え部３５にスイッチオフ信号を送信する。それにより、切替え部３５は、スイッチ１１を開ける。この結果、キャパシタンス２７が充電される。

　なお、ステップＳ３での圧電出力取得終了からステップＳ４でのディスチャージ開始までの時間ｔ１は、なるべく短い方が好ましい。
In step S <b> 3, the acquisition unit 36 of the control unit 31 acquires the digital voltage signal from the detection unit 41. As described above, at this time, the capacitance 27 is in a charged state.

In step S4, the control unit 31 opens and closes the switch 11 by transmitting a control signal to the switching unit 35, thereby causing the discharge process (the capacitance 27 is discharged for a predetermined time after the digital voltage signal is acquired). )I do. Specifically, the control unit 31 transmits a switch-on signal to the switching unit 35. Thereby, the switching unit 35 closes the switch 11. Thereby, the capacitance 27 is discharged. When a predetermined time has elapsed, the control unit 31 transmits a switch-off signal to the switching unit 35. Thereby, the switching unit 35 opens the switch 11. As a result, the capacitance 27 is charged.

It should be noted that the time t 1 from the end of the piezoelectric output acquisition in step S3 to the start of discharge in step S4 is preferably as short as possible.

　ステップＳ４が終了すると、プロセスはステップＳ１に戻る。

　この結果、図５に示すように、所定の周期でディスチャージ操作が行われ、そのたびにキャパシタンス２７が放電される。また、タッチパネル駆動→圧電出力取得→ディスチャージがこの順番で行われており、つまりタッチパネル駆動と圧電出力取得は異なるタイミングで行われている。したがって、圧電シート２１の圧電信号がタッチパネル２３からのノイズの影響を受けにくくなる。

　なお、この実施形態では、タッチパネル駆動の周期及び圧電出力取得及びディスチャージの周期はそれぞれ一定である。
When step S4 ends, the process returns to step S1.

As a result, as shown in FIG. 5, a discharge operation is performed at a predetermined cycle, and the capacitance 27 is discharged each time. Further, touch panel drive → piezoelectric output acquisition → discharge is performed in this order, that is, touch panel drive and piezoelectric output acquisition are performed at different timings. Therefore, the piezoelectric signal of the piezoelectric sheet 21 is not easily affected by noise from the touch panel 23.

In this embodiment, the touch panel drive cycle and the piezoelectric output acquisition and discharge cycle are constant.

　次に、図４を用いて、制御部３１によるタッチ期間における圧電出力加算による押圧力データ出力制御を説明する。

　ステップＳ５では、制御部３１の取得部３６は、圧力センサ３へのタッチが有るか無いかに関係無く、常に圧電出力取得を行っている。なお、取得する圧電出力は圧電信号が０の場合も含む。圧電出力取得が行われれば、プロセスはステップＳ６に移行する。
Next, the pressing force data output control by the piezoelectric output addition in the touch period by the control unit 31 will be described with reference to FIG.

In step S <b> 5, the acquisition unit 36 of the control unit 31 always performs piezoelectric output acquisition regardless of whether or not there is a touch on the pressure sensor 3. The acquired piezoelectric output includes the case where the piezoelectric signal is zero. If piezoelectric output acquisition is performed, the process proceeds to step S6.

　タッチが開始されれば（ステップＳ６でＹｅｓ、図５のＡ）、プロセスはステップＳ７に移行する。タッチが無い場合（ステップＳ６でＮｏ、図５のＣ）は、プロセスはステップＳ５に戻る。
If the touch is started (Yes in step S6, A in FIG. 5), the process proceeds to step S7. If there is no touch (No in step S6, C in FIG. 5), the process returns to step S5.

　ステップＳ７では、算出部３７が、取得部３６により取得された圧電出力の値を加算する。

　つまり、タッチ開始後に、タッチがなくなるまで算出部３７が加算を繰り返す（図５のＢ）。ただし、タッチ検出部７は、実際のタッチに対して検出が遅れることがある。よって、算出部３７の順次加算は、タッチ検出（図５のＤ）後、当該タッチ検出の時点から一定時間さかのぼったデータから加算すると、より精度が上がる。

　ステップＳ８では、算出部３７は、加算された押圧力データを保存又は外部に出力する。その後、プロセスはステップＳ５に戻る。つまり、１回のタッチがあればその押圧力データが取得され、その後に保存又は外部に出力される。
In step S <b> 7, the calculation unit 37 adds the piezoelectric output values acquired by the acquisition unit 36.

That is, after the touch is started, the calculation unit 37 repeats the addition until there is no touch (B in FIG. 5). However, the detection of the touch detection unit 7 may be delayed with respect to the actual touch. Therefore, the accuracy of the sequential addition of the calculation unit 37 is further improved by adding from the data that goes back for a certain time after the touch detection (D in FIG. 5).

In step S8, the calculation unit 37 saves or outputs the added pressing force data to the outside. Thereafter, the process returns to step S5. That is, if there is a single touch, the pressing force data is acquired and then stored or output to the outside.

　具体的には、例えば操作者の指又はペンが圧力センサ３を押すと、タッチ検出部７がタッチを検出する（図５のＤ）。そして、タッチ検出信号が、タッチ検出部７から制御部３１に送信される。これにより、制御部３１では、算出部３７が、検出部４１から取得される圧電出力を順次加算していく（図５のＢ）。その結果、押圧力データが得られる。そして、算出部３７は、押圧力データ保存又は外部に出力する。
Specifically, for example, when the operator's finger or pen presses the pressure sensor 3, the touch detection unit 7 detects a touch (D in FIG. 5). Then, a touch detection signal is transmitted from the touch detection unit 7 to the control unit 31. Thereby, in the control part 31, the calculation part 37 adds the piezoelectric output acquired from the detection part 41 sequentially (B of FIG. 5). As a result, pressing force data is obtained. And the calculation part 37 preserve | saves pressing force data or outputs it outside.

　この実施形態では、スイッチ１１のオン抵抗Ｒ（Ω）とキャパシタンスの容量Ｃ（Ｆ）が以下の式を満たしている。

　Ｒ（Ω）Ｃ（Ｆ）＜１０ｍｓ

　この装置では、上記式を満たしているので、スイッチ１１を閉じてからキャパシタンス２７に貯まった電荷がすべて放電されるのに要する時間が短くなる。その結果、キャパシタンス２７を放電する所定時間を短く設定できる。なお、上記の条件は必須ではない。
In this embodiment, the on-resistance R (Ω) of the switch 11 and the capacitance C (F) of the capacitance satisfy the following expression.

R (Ω) C (F) <10 ms

In this device, since the above equation is satisfied, the time required for discharging all the electric charges accumulated in the capacitance 27 after the switch 11 is closed is shortened. As a result, the predetermined time for discharging the capacitance 27 can be set short. Note that the above conditions are not essential.

　上記の構成及び機能によって、圧電出力が例えば積分回路５又はＡＤ変換部３９の出力限界を振り切ってしまい、その分が検出できなくなることが防止される。その効果を、図６を用いて説明する。図６は、真の押圧力の変化、従来でのデジタル電圧信号の変化、本実施形態のデジタル電圧信号の変化を示したグラフである。

　図６において、「真の押圧力」とは、指等でタッチパネルを押している力のことである。

　従来方法（ディスチャージが無い）の場合には、ノイズの影響によって圧電出力が例えば積分回路５又はＡＤ変換部３９の出力限界を超えてしまい、そのために押圧力を正確に検出できない。
With the above-described configuration and function, it is possible to prevent the piezoelectric output from surpassing the output limit of, for example, the integration circuit 5 or the AD conversion unit 39 and making that amount undetectable. The effect will be described with reference to FIG. FIG. 6 is a graph showing changes in the true pressing force, changes in the conventional digital voltage signal, and changes in the digital voltage signal of the present embodiment.

In FIG. 6, “true pressing force” refers to a force pressing the touch panel with a finger or the like.

In the case of the conventional method (no discharge), the piezoelectric output exceeds the output limit of, for example, the integration circuit 5 or the AD conversion unit 39 due to the influence of noise, so that the pressing force cannot be accurately detected.

　本実施形態のように、ディスチャージ制御をすることで、圧電出力が例えば積分回路５又はＡＤ変換部３９の出力限界を振り切ることを防止できる。また、繰り返しディスチャージすることでデジタル電圧信号はゼロになるが、取得した値を加算していくことで現在の押圧力を算出できる。なお、タッチ検出されていない（つまり、押圧が無い）場合には、圧電出力の値は加算されず、つまり押圧力が算出されない。

　さらに、押圧力にノイズ成分が重畳されるが、毎回タッチありでの時点でキャパシタンス２７の電荷をゼロとしているので、このノイズ成分の影響は生じない。
By performing discharge control as in the present embodiment, it is possible to prevent the piezoelectric output from shaking off the output limit of the integration circuit 5 or the AD conversion unit 39, for example. Further, the digital voltage signal becomes zero by repeatedly discharging, but the current pressing force can be calculated by adding the acquired values. Note that when the touch is not detected (that is, there is no pressing), the value of the piezoelectric output is not added, that is, the pressing force is not calculated.

Furthermore, although a noise component is superimposed on the pressing force, since the electric charge of the capacitance 27 is set to zero at every touch, the influence of the noise component does not occur.

２．第２実施形態

　第１実施形態ではタッチパネル駆動と圧電力取得及びディスチャージとは交互に行われていたが、本発明はそのような実施形態に限定されない。例えば、タッチパネル駆動は適宜間引きされてもよい。

　図７を用いて、そのような実施形態を説明する。図７は、制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャートである。なお、以下の各実施形態の基本的な構成、機能及び効果は同じであるので、以下の説明では異なる点を中心に説明する。
2. Second embodiment

In the first embodiment, the touch panel drive, the piezoelectric power acquisition, and the discharge are alternately performed, but the present invention is not limited to such an embodiment. For example, the touch panel drive may be thinned out as appropriate.

Such an embodiment will be described with reference to FIG. FIG. 7 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit. In addition, since the fundamental structure, function, and effect of each following embodiment are the same, in the following description, it demonstrates focusing on a different point.

　図７においては、ステップＳ１の前には、ステップＳ２１が挿入されている。ステップＳ２１では、Ｎ（ｍｏｄ　ｍ）＝＝正の整数、Ｎ＝Ｎ＋１（Ｎ：総回数、ｍ：間引き数）の条件を満たせばプロセスはステップＳ１に移行し、上記の式の条件が満たされなければプロセスはステップＳ１及びステップＳ２（つまり、タッチパネル駆動）をスキップしてステップＳ３に移行する。

　以上の制御では、間引き数ｍの設定によって、圧電出力取得及びディスチャージに対してタッチパネル駆動を行う割合を設定できる。
In FIG. 7, step S21 is inserted before step S1. In step S21, if the condition of N (mod m) == positive integer and N = N + 1 (N: total number of times, m: thinning number) is satisfied, the process proceeds to step S1, and the condition of the above equation is satisfied. If not, the process skips step S1 and step S2 (that is, touch panel driving) and proceeds to step S3.

In the above control, the ratio of performing the touch panel drive for the piezoelectric output acquisition and the discharge can be set by setting the thinning number m.

３．第３実施形態

　第１実施形態ではタッチパネル駆動と圧電力取得及びディスチャージとは交互に行われていたが、本発明はそのような実施形態に限定されない。例えば、圧電出力取得及びディスチャージは適宜間引きされてもよい。

　図８を用いて、そのような実施形態を説明する。図８は、制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャートである。
3. Third embodiment

In the first embodiment, the touch panel drive, the piezoelectric power acquisition, and the discharge are alternately performed, but the present invention is not limited to such an embodiment. For example, piezoelectric output acquisition and discharge may be thinned out as appropriate.

Such an embodiment will be described with reference to FIG. FIG. 8 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.

　図８においては、ステップＳ２とステップＳ３との間には、ステップＳ２１が挿入されている。ステップＳ２１では、上記の式の条件が満たされればプロセスはステップＳ３に移行し、上記式の条件が満たされなければプロセスはステップＳ３及びステップＳ４（つまり、圧電出力取得及びディスチャージ）をスキップしてステップＳ１に移行する。

　以上の制御では、間引き数ｍの設定によって、タッチパネル駆動に対して圧電力取得及びディスチャージを行う割合を設定できる。
In FIG. 8, step S21 is inserted between step S2 and step S3. In step S21, if the condition of the above equation is satisfied, the process proceeds to step S3. If the condition of the above equation is not satisfied, the process skips step S3 and step S4 (that is, piezoelectric output acquisition and discharge). The process proceeds to step S1.

In the above control, by setting the thinning-out number m, it is possible to set the ratio of performing the piezoelectric power acquisition and discharging with respect to the touch panel drive.

４．第４実施形態

　第１実施形態では繰り返される圧電出力の取得（読み込み）周期は一定周期であったが、本発明の実施形態はそれに限定されない。むしろ、取得周期が一定の場合は、その周期と同程度の周期の交流ノイズが押圧検出に大きな影響を与えることがある。

　そこで、例えば、圧電出力の取得周期を交流ノイズの周期からずらした周期に設定する。特に、蛍光灯や電源、その他電子機器や部品からの商用電源周波数由来の交流ノイズの影響が大きいので、デジタル電圧信号の取得周期は、５０Ｈｚ±２％以内又は６０Ｈｚ±２％以内にならないようにする。このように算出部３７が圧電出力を取得する周期が、商用電源周波数から２％以上離れているので、蛍光灯、電源又はその他電子機器若しくは部品からの商用電源周波数由来の交流ノイズの影響が少なくなる。
4). Fourth embodiment

In the first embodiment, the repeated acquisition (reading) period of the piezoelectric output is a fixed period, but the embodiment of the present invention is not limited thereto. Rather, when the acquisition period is constant, AC noise having a period similar to that period may greatly affect the pressure detection.

Therefore, for example, the piezoelectric output acquisition cycle is set to a cycle shifted from the AC noise cycle. In particular, since the influence of AC noise derived from commercial power supply frequency from fluorescent lamps, power supplies, other electronic devices and parts is large, the acquisition cycle of digital voltage signals should not be within 50Hz ± 2% or within 60Hz ± 2%. To do. Thus, since the period at which the calculation unit 37 acquires the piezoelectric output is 2% or more away from the commercial power supply frequency, the influence of the AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic devices or parts is small. Become.

　図９を用いて、そのような実施形態を説明する。図９は、制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャートである。

　図９では、ステップＳ２とステップＳ３との間に、ステップＳ２２が挿入されている。ステップＳ２２は、「ＷＡＩＴ」であり、一連のフローの中での遅延時間を確保するステップである。
Such an embodiment will be described with reference to FIG. FIG. 9 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.

In FIG. 9, step S22 is inserted between step S2 and step S3. Step S22 is “WAIT”, which is a step of securing a delay time in a series of flows.

５．第５実施形態

　第４実施形態では圧電出力の取得周期を交流ノイズの周期からずらした周期に設定することで蛍光灯、電源又はその他電子機器若しくは部品からの商用電源周波数由来の交流ノイズの影響が少なくしていた。しかし、ノイズの影響を減らすための手法は第４実施形態に限定されない。

　例えば、算出部３７が圧電出力を取得する周期を不定期にすることで、上記効果を実現してもよい。

　圧電出力の取得周期を不定期にした場合の一例として、１周期目が１０ｍｓ、２周期目が１１ｍｓ、３周期目が９ｍｓ、４周期目が１２ｍｓ、５周期目が１２ｍｓ、６周期目が７ｍｓにする。
5. Fifth embodiment

In the fourth embodiment, the influence of the AC noise derived from the commercial power supply frequency from the fluorescent lamp, the power supply, or other electronic devices or parts is reduced by setting the acquisition period of the piezoelectric output to a period shifted from the AC noise period. . However, the method for reducing the influence of noise is not limited to the fourth embodiment.

For example, the above effect may be realized by making the period in which the calculation unit 37 acquires the piezoelectric output irregular.

As an example when the piezoelectric output acquisition cycle is irregular, the first cycle is 10 ms, the second cycle is 11 ms, the third cycle is 9 ms, the fourth cycle is 12 ms, the fifth cycle is 12 ms, and the sixth cycle is 7 ms. To.

　圧電出力の取得周期をランダムにするために、例えば、一連のフローの中でランダムな遅延時間を挿入する。図１０を用いて、そのような実施形態を説明する。図１０は、制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャートである。

　図１０では、ステップＳ２とステップＳ３との間に、ステップＳ２３が挿入されている。ステップＳ２３は、「ランダムＷＡＩＴ」であり、一連のフローの中で不定期な遅延時間を確保するステップである。
In order to make the acquisition period of the piezoelectric output random, for example, a random delay time is inserted in a series of flows. Such an embodiment will be described with reference to FIG. FIG. 10 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.

In FIG. 10, step S23 is inserted between step S2 and step S3. Step S23 is “Random WAIT” and is a step of securing an irregular delay time in a series of flows.

６．第６実施形態

　第５実施形態では圧電出力取得の周期を不定としたが、それに伴いタッチパネル駆動の周期も不定となった。この場合、積分回路以外にノイズの影響を受けやすいデバイスのタイミングが取りにくい。そこで、圧電出力取得の周期を不定としながらも、タッチパネル駆動の周期を一定にすることが望まれる。図１１を用いて、そのような実施形態を説明する。

　図１１に示す実施形態では、タッチ検出を一定周期に保つために、第５実施形態の制御に対して、調整のための遅延時間を追加している。図１１は、制御部によるタッチパネル駆動、圧電出力取得、キャパシタンスのディスチャージ制御を説明するためのフローチャートである。
6). Sixth embodiment

In the fifth embodiment, the period for obtaining the piezoelectric output is indefinite, but the period for driving the touch panel is also indefinite. In this case, it is difficult to take timing for devices that are susceptible to noise other than the integration circuit. Therefore, it is desirable to make the touch panel drive cycle constant while making the piezoelectric output acquisition cycle indefinite. Such an embodiment will be described with reference to FIG.

In the embodiment shown in FIG. 11, a delay time for adjustment is added to the control of the fifth embodiment in order to keep touch detection at a constant period. FIG. 11 is a flowchart for explaining touch panel drive, piezoelectric output acquisition, and capacitance discharge control by the control unit.

　具体的には、ステップＳ４の後に、ステップＳ２４が挿入されている。ステップＳ２４は、「調整ＷＡＩＴ」であり、タッチ検出を一定に保つための遅延時間が確保されるステップである。この場合、ステップＳ２３の「ランダムＷＡＩＴ」に応じてステップＳ２４の「調整ＷＡＩＴ」を実行することで、タッチ駆動の周期を一定にできる。
Specifically, step S24 is inserted after step S4. Step S24 is “adjustment WAIT”, and is a step in which a delay time for keeping the touch detection constant is secured. In this case, by executing “Adjustment WAIT” in Step S24 in response to “Random WAIT” in Step S23, the touch driving cycle can be made constant.

７．第７実施形態

　オペアンプ２５及びキャパシタンス２７により構成される積分回路５は、図６に示された構成に限られない。例えば、図１２に示すようなオペアンプ２５及びキャパシタンス２７Ａの構成を有する積分回路５Ａを用いてもよい。図１２は、積分回路の概略図である。

　積分回路５Ａにおいては、オペアンプ２５の「＋」を付した入力が、圧電シート２１の圧電検出電極（図示せず）に接続されており、「－」を付した入力が、抵抗を介して、基準電極（図示せず）及びグランド電位に接続されている。また、基準電極は、グランド電位に接続されている。この場合、圧電検出電極（図示せず）と基準電極（図示せず）との間に正の電位差を有した圧電信号が入力されると、オペアンプ２５から正の電位差を有する信号が出力される（非反転増幅）。
7). Seventh embodiment

The integrating circuit 5 including the operational amplifier 25 and the capacitance 27 is not limited to the configuration shown in FIG. For example, an integrating circuit 5A having a configuration of an operational amplifier 25 and a capacitance 27A as shown in FIG. 12 may be used. FIG. 12 is a schematic diagram of the integration circuit.

In the integrating circuit 5A, an input with “+” of the operational amplifier 25 is connected to a piezoelectric detection electrode (not shown) of the piezoelectric sheet 21, and an input with “−” is connected via a resistor. A reference electrode (not shown) is connected to a ground potential. The reference electrode is connected to the ground potential. In this case, when a piezoelectric signal having a positive potential difference is input between a piezoelectric detection electrode (not shown) and a reference electrode (not shown), a signal having a positive potential difference is output from the operational amplifier 25. (Non-inverting amplification).

　また、キャパシタンス２７Ａは、一端がオペアンプ２５の「＋」を付した入力に接続され、他端がグランド電位に接続されている。

　スイッチ１１Ａは、キャパシタンス２７Ａと並列に接続されており、キャパシタンス２７Ａの充電状態と放電状態とを切替え可能である。具体的には、スイッチ１１Ａは、一端がオペアンプ２５の「＋」を付した入力に接続され、他端がグランド電位に接続されている。

　この実施形態では、第１実施形態と同様に、スイッチ１１Ａがディスチャージ制御されることで、キャパシタンス２７を繰り返し放電できる。
Further, one end of the capacitance 27A is connected to the input with “+” of the operational amplifier 25, and the other end is connected to the ground potential.

The switch 11A is connected in parallel with the capacitance 27A and can switch between a charged state and a discharged state of the capacitance 27A. Specifically, one end of the switch 11A is connected to an input with “+” of the operational amplifier 25, and the other end is connected to the ground potential.

In this embodiment, similarly to the first embodiment, the capacitance 11 can be repeatedly discharged by controlling the discharge of the switch 11A.

８．実施形態の共通事項

　圧力検出装置（例えば、圧力検出装置１）は、圧力センサと、タッチ検出部と、積分回路と、スイッチと、ＡＤ変換部と、取得部と、切替え部と、算出部とを備えている。

　圧力センサ（例えば、圧力センサ３）は、与えられた荷重に応じた圧電信号を発生する圧電シート（例えば、圧電シート２１）を有する。

　タッチ検出部（例えば、タッチ検出部７）は、圧力センサへの接触を検出する。

　積分回路（例えば、積分回路５）は、圧電シートに接続された入力部を有するアンプと、入力部に一端が接続されるキャパシタンスとを有する。

　スイッチ（例えば、スイッチ１１）は、キャパシタンスの充電状態と放電状態とを切替え可能である。

　ＡＤ変換部（例えば、ＡＤ変換部３９）は、積分回路から出力されるアナログ電圧信号をデジタル電圧信号に変換する。

　取得部（例えば、取得部３６）は、キャパシタンスの充電状態においてデジタル電圧信号を取得する。

　切替え部（切替え部３５）は、スイッチを制御することで、キャパシタンスの充電状態と放電状態とを交互に繰り返し、かつデジタル電圧信号が取得された後にキャパシタンスを所定時間だけ放電状態にする。

　算出部（例えば、算出部３７）は、タッチ検出部が圧力センサへの接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力測定値を算出する。
8). Common items of embodiment

The pressure detection device (for example, the pressure detection device 1) includes a pressure sensor, a touch detection unit, an integration circuit, a switch, an AD conversion unit, an acquisition unit, a switching unit, and a calculation unit.

The pressure sensor (for example, the pressure sensor 3) includes a piezoelectric sheet (for example, the piezoelectric sheet 21) that generates a piezoelectric signal corresponding to a given load.

The touch detection unit (for example, touch detection unit 7) detects contact with the pressure sensor.

The integration circuit (for example, the integration circuit 5) includes an amplifier having an input unit connected to the piezoelectric sheet and a capacitance having one end connected to the input unit.

The switch (for example, the switch 11) can switch between a charged state and a discharged state of the capacitance.

The AD conversion unit (for example, the AD conversion unit 39) converts an analog voltage signal output from the integration circuit into a digital voltage signal.

The acquisition unit (for example, the acquisition unit 36) acquires a digital voltage signal in a charged state of capacitance.

The switching unit (switching unit 35) controls the switch to alternately repeat the charge state and the discharge state of the capacitance, and sets the capacitance to the discharge state for a predetermined time after the digital voltage signal is acquired.

The calculation unit (for example, the calculation unit 37) calculates the pressing force measurement value by adding the acquired digital voltage signal while the touch detection unit detects contact with the pressure sensor.

　この装置では、キャパシタンスは、切替え部によって充電状態と放電状態とを交互に繰り返される（図４及び図５を参照）。取得部は、キャパシタンスの充電状態においてデジタル電圧信号を取得する（例えば、図３のステップＳ３）。その後、キャパシタンスは所定時間だけ放電状態にされる（例えば、図３のステップＳ４）。算出部は、タッチ検出部が圧力センサへの接触を検出している間、取得されたデジタル電圧信号を加算していくことで押圧力測定値を算出する（例えば、図４のステップＳ７）。したがって、現在の押圧力の値が得られる。

　また、キャパシタンスの放電を繰り返して行うことで、従来であればノイズの影響で圧電出力が例えば積分回路の出力限界を超えてしまうような場合でも、そのような事態を防止できる（図６を参照）。
In this device, the capacitance is alternately repeated between the charged state and the discharged state by the switching unit (see FIGS. 4 and 5). The acquisition unit acquires a digital voltage signal in the charged state of the capacitance (for example, step S3 in FIG. 3). Thereafter, the capacitance is discharged for a predetermined time (for example, step S4 in FIG. 3). The calculation unit calculates the pressing force measurement value by adding the acquired digital voltage signal while the touch detection unit detects contact with the pressure sensor (for example, step S7 in FIG. 4). Therefore, the current pressing force value is obtained.

Further, by repeatedly discharging the capacitance, such a situation can be prevented even if the piezoelectric output exceeds the output limit of the integration circuit, for example, due to the influence of noise (see FIG. 6). ).

９．他の実施形態

　以上、本発明の一実施形態について説明したが、本発明は上記実施形態に限定されるものではなく、発明の要旨を逸脱しない範囲で種々の変更が可能である。特に、本明細書に書かれた複数の実施形態及び変形例は必要に応じて任意に組み合せ可能である。

　例えば、第２実施形態と第３実施形態を適宜組み合わせてもよい。また、第７実施形態を第２～第６実施形態のいずれかに組み合わせてもよい。
9. Other embodiments

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.

For example, the second embodiment and the third embodiment may be appropriately combined. Further, the seventh embodiment may be combined with any of the second to sixth embodiments.

　第１実施形態における圧力検出装置では、圧力センサのタッチパネルを圧電シートに重ねて配置したが、本発明はこれに限定されない。例えば、タッチパネルのタッチ検出電極を形成する基材が圧電シートを兼ねていてもよい。また、第１実施形態では、静電容量方式により、接触対象物の圧力センサへの接触を検出していた。しかし、接触対象物の圧力センサへの接触の検出方法は、静電容量方式に限られない。静電容量方式以外の方法（例えば、抵抗膜方式、光学方式、超音波方式など）により、接触対象物の圧力センサへの接触を検出してもよい。
In the pressure detection device according to the first embodiment, the touch panel of the pressure sensor is disposed so as to overlap the piezoelectric sheet, but the present invention is not limited to this. For example, the base material forming the touch detection electrode of the touch panel may also serve as the piezoelectric sheet. Moreover, in 1st Embodiment, the contact to the pressure sensor of the contact target object was detected with the electrostatic capacitance system. However, the method for detecting contact of the contact object with the pressure sensor is not limited to the capacitance method. The contact of the contact object with the pressure sensor may be detected by a method other than the capacitance method (for example, a resistance film method, an optical method, an ultrasonic method, etc.).

　本発明は、与えられた荷重に応じた圧電信号を発生する圧電シートを用いた、圧力検出装置に広く適用できる。
The present invention can be widely applied to a pressure detection device using a piezoelectric sheet that generates a piezoelectric signal corresponding to a given load.

１　　　　：圧力検出装置

３　　　　：圧力センサ

５　　　　：積分回路

７　　　　：タッチ検出部

９　　　　：マイコン

１１　　　：スイッチ

２１　　　：圧電シート

２３　　　：タッチパネル

２５　　　：オペアンプ

２７　　　：キャパシタンス

２９　　　：駆動部

３１　　　：制御部

３５　　　：切替え部

３６　　　：取得部

３７　　　：算出部

３９　　　：ＡＤ変換部
1: Pressure detector

3: Pressure sensor

5: Integration circuit

7: Touch detection unit

9: Microcomputer

11: Switch

21: Piezoelectric sheet

23: Touch panel

25: Operational amplifier

27: Capacitance

29: Drive unit

31: Control unit

35: Switching unit

36: Acquisition unit

37: calculation unit

39: AD converter

Claims (8)


  1. 　与えられた荷重に応じた圧電信号を発生する圧電シートを有する圧力センサと、

    　前記圧力センサへの接触を検出するタッチ検出部と、

    　前記圧電シートに接続された入力部を有するアンプと、前記入力部に一端が接続されるキャパシタンスとを有する、積分回路と、

    　前記キャパシタンスの充電状態と放電状態とを切替え可能なスイッチと、

    　前記積分回路から出力されるアナログ電圧信号をデジタル電圧信号に変換するＡＤ変換部と、

    　前記キャパシタンスの前記充電状態において前記デジタル電圧信号を取得する取得部と、

    　前記スイッチを制御することで、前記キャパシタンスの前記充電状態と前記放電状態とを交互に繰り返し、かつ前記デジタル電圧信号が取得された後に前記キャパシタンスを所定時間だけ前記放電状態にする切替え部と、

    　前記タッチ検出部が前記圧力センサへの接触を検出している間、取得された前記デジタル電圧信号を加算していくことで押圧力測定値を算出する算出部と、

    を備える、圧力検出装置。
    A pressure sensor having a piezoelectric sheet for generating a piezoelectric signal corresponding to a given load;

    A touch detector for detecting contact with the pressure sensor;

    An integrating circuit having an amplifier having an input connected to the piezoelectric sheet, and a capacitance having one end connected to the input;

    A switch capable of switching between a charged state and a discharged state of the capacitance;

    An AD converter for converting an analog voltage signal output from the integrating circuit into a digital voltage signal;

    An acquisition unit for acquiring the digital voltage signal in the charged state of the capacitance;

    By switching the switch, the charge state and the discharge state of the capacitance are alternately repeated, and after the digital voltage signal is acquired, the switching unit for setting the capacitance to the discharge state for a predetermined time;

    While the touch detection unit detects contact with the pressure sensor, a calculation unit that calculates a pressing force measurement value by adding the acquired digital voltage signal;

    A pressure detection device.

  2. 　前記圧力センサが、前記タッチ検出部に接続されたタッチパネルを有し、

    　前記タッチ検出部が、前記デジタル電圧信号を取得するタイミングとは異なるタイミングで、前記タッチパネルを駆動する駆動部を有する、請求項１に記載の圧力検出装置。
    The pressure sensor has a touch panel connected to the touch detection unit,

    The pressure detection device according to claim 1, wherein the touch detection unit includes a drive unit that drives the touch panel at a timing different from a timing at which the digital voltage signal is acquired.

  3. 　前記スイッチのオン抵抗Ｒ（Ω）と前記キャパシタンスの容量Ｃ（Ｆ）が以下の式を満たす、

    　Ｒ（Ω）Ｃ（Ｆ）＜１０ｍｓ

    　請求項１又は２に記載の圧力検出装置。
    The on-resistance R (Ω) of the switch and the capacitance C (F) of the capacitance satisfy the following formula:

    R (Ω) C (F) <10 ms

    The pressure detection device according to claim 1 or 2.

  4. 　前記取得部が前記デジタル電圧信号を取得する周期が、商用電源周波数から２％以上離れている、請求項１～３のいずれかに記載の圧力検出装置。
    The pressure detection device according to any one of claims 1 to 3, wherein a period at which the acquisition unit acquires the digital voltage signal is 2% or more away from a commercial power supply frequency.

  5. 　前記取得部が前記デジタル電圧信号を取得する周期が不定期である、請求項１～３のいずれかに記載の圧力検出装置。
    The pressure detection device according to any one of claims 1 to 3, wherein a period at which the acquisition unit acquires the digital voltage signal is irregular.

  6. 　与えられた荷重に応じた圧電信号を発生する圧電シートを有する圧力センサと、前記圧力センサへの接触を検出するタッチ検出部と、前記圧電シートに接続された入力部を有するアンプと前記入力部に一端が接続されるキャパシタンスとを有する積分回路と、前記キャパシタンスの充電状態と放電状態とを切替え可能なスイッチと、前記積分回路から出力されるアナログ電圧信号をデジタル電圧信号に変換するＡＤ変換部と、を備えた圧力検出装置の制御方法であって、

    　前記キャパシタンスの前記充電状態において前記デジタル電圧信号を取得する取得ステップと、

    　前記スイッチを制御することで、前記デジタル電圧信号が取得された後に前記キャパシタンスを前記充電状態から前記放電状態に切替え、切り替え後所定時間だけ前記放電状態を維持する切替えステップと、

    　前記タッチ検出部が前記圧力センサへの接触を検出している間、取得された前記デジタル電圧信号を加算していくことで押圧力測定値を算出する算出ステップと、

    を備える、圧力検出装置の制御方法。
    A pressure sensor having a piezoelectric sheet for generating a piezoelectric signal corresponding to a given load; a touch detection unit for detecting contact with the pressure sensor; an amplifier having an input unit connected to the piezoelectric sheet; and the input unit. An integration circuit having one end connected to the capacitor, a switch capable of switching between a charge state and a discharge state of the capacitance, and an AD conversion unit that converts an analog voltage signal output from the integration circuit into a digital voltage signal A method of controlling a pressure detection device comprising:

    Obtaining the digital voltage signal in the charged state of the capacitance;

    A switching step of controlling the switch to switch the capacitance from the charged state to the discharged state after the digital voltage signal is acquired, and maintaining the discharged state for a predetermined time after switching;

    A calculation step of calculating a pressing force measurement value by adding the acquired digital voltage signal while the touch detection unit detects contact with the pressure sensor;

    A method for controlling the pressure detection device.

  7. 　前記デジタル電圧信号を取得するタイミングとは異なるタイミングで、前記タッチ検出部に接続されたタッチパネルを駆動する駆動ステップを、さらに備える、請求項６に記載の圧力検出装置の制御方法。
    The control method of the pressure detection device according to claim 6, further comprising a driving step of driving the touch panel connected to the touch detection unit at a timing different from the timing of acquiring the digital voltage signal.

  8. 　コンピュータの記憶部に保存され、請求項６又は７に記載の圧力検出装置の制御方法を前記コンピュータに実行させるプログラム。
    A program stored in a storage unit of a computer and causing the computer to execute the control method of the pressure detection device according to claim 6 or 7.
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