WO2018076343A1 - 电容检测装置、方法和压力检测系统 - Google Patents

电容检测装置、方法和压力检测系统 Download PDF

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Publication number
WO2018076343A1
WO2018076343A1 PCT/CN2016/104027 CN2016104027W WO2018076343A1 WO 2018076343 A1 WO2018076343 A1 WO 2018076343A1 CN 2016104027 W CN2016104027 W CN 2016104027W WO 2018076343 A1 WO2018076343 A1 WO 2018076343A1
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Prior art keywords
capacitor
switch
capacitance
variable
module
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PCT/CN2016/104027
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English (en)
French (fr)
Inventor
蒋宏
Original Assignee
深圳市汇顶科技股份有限公司
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Filing date
Publication date
Application filed by 深圳市汇顶科技股份有限公司 filed Critical 深圳市汇顶科技股份有限公司
Priority to PCT/CN2016/104027 priority Critical patent/WO2018076343A1/zh
Priority to CN201680001429.XA priority patent/CN106537106B/zh
Priority to EP16910786.9A priority patent/EP3340021A4/en
Priority to KR1020187003344A priority patent/KR102020998B1/ko
Priority to US15/871,865 priority patent/US10345980B2/en
Publication of WO2018076343A1 publication Critical patent/WO2018076343A1/zh

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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
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
    • G01D5/241—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes
    • 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
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
    • G01L1/144—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors with associated circuitry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2605—Measuring capacitance
    • 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
    • G06F3/0414—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using force sensing means to determine a position
    • 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
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • 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
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/04166—Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving
    • 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
    • G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
    • G06F3/0447—Position sensing using the local deformation of sensor cells

Definitions

  • Embodiments of the present invention relate to the field of touch technology, and more particularly, to a capacitance detecting apparatus, method, and pressure detecting system.
  • the touch technology is applied to the smart terminal, so that the user can realize the operation of the terminal by gesture operation, and get rid of the traditional mechanical keyboard, so that the human-computer interaction is more straightforward.
  • touch technology can no longer meet the needs of users for more dimensional input.
  • a capacitive active pen is added to the capacitive touch screen, and the capacitive active pen touches the touch screen, and the pressure changes, but the touch screen cannot perform different writing operations according to the pressure change.
  • different operations are not given according to the change of the button or fingerprint pressure. In this way, it is difficult to simulate the experience of real pen writing through touch technology, affecting the accuracy of input, and the user experience is not good.
  • the present invention proposes a capacitance detecting device that detects a difference in capacitance between two capacitors.
  • the embodiment of the invention provides a capacitance detecting device, a method and a pressure detecting system, which can realize the detection of the large capacitance with a small capacitance, and can improve the accuracy of the pressure detection by using the capacitance detection of the invention.
  • the present invention provides a capacitance detecting apparatus, the apparatus comprising a differential amplifier, a first capacitor, a second capacitor, a charging module, a control module, and a calculation module, the differential amplifier including a first input end, a second An input terminal, a first output terminal, and a second output terminal; the first input terminal is connected to a third capacitor to be tested, and the second input terminal is connected to a fourth capacitor to be tested, the first input The first output end and the first output end are respectively connected to both ends of the first capacitor, and the second input end and the second output end are respectively connected to both ends of the second capacitor, the first output Both the end and the second output are connected to the computing module; in the first phase, the The control module is configured to control the charging module to charge the third capacitor and the fourth capacitor, and the control module is further configured to control the first capacitor and the second capacitor to discharge; The control module is configured to control the charging module to disconnect charging the third capacitor and the fourth capacitor, and the control module is further configured to control the third capacitor to
  • the two capacitors to be tested can be charged, and then the charge amount of the capacitor to be tested is transferred to the capacitor in the capacitance detecting circuit, and the voltage discharged by the capacitor to be tested is amplified and output to the calculation module through the differential amplifier. In this way, the voltage difference calculation of the output of the differential amplifier can be used to detect the difference in capacitance of different capacitors.
  • the pressure detection can be realized by the capacitance detection of the embodiment of the invention, which can improve the detection sensitivity and can make the user experience better.
  • the apparatus further includes a first variable capacitor and a second variable capacitor, the first variable capacitor and the third capacitor being connected in parallel, The second variable capacitor and the fourth capacitor are connected in parallel.
  • the capacitance of the first variable capacitor is before the capacitance values of the third capacitor and the fourth capacitor are changed by the outside world.
  • the sum of the capacitances of the third capacitor is equal to the sum of the capacitance of the second variable capacitor and the capacitance of the fourth capacitor.
  • the capacitance detecting device further includes a first variable resistor and a second variable resistor, the first variable resistor and the The first capacitors are connected in parallel, and the second variable resistor and the second capacitor are connected in parallel.
  • the resistance value of the first variable resistor and the resistance value of the second variable resistor are the same at the same time.
  • the resistance values of the two variable resistors can be the same at the same time, so that the symmetrical circuit design can make the sensitivity of the circuit better.
  • the capacitance of the first capacitor is the same as the capacitance of the second capacitor.
  • the charging module is a power source;
  • the control module includes a first switch and a second switch; a power connection, the other end of the first switch is connected to one end of the third capacitor, the other end of the third capacitor is grounded, and the first switch is closed to cause the power source to charge the third capacitor, Discharging the charging of the third capacitor by the power source when the first switch is off; one end of the second switch is connected to the power source, and the other end of the second switch is opposite to the fourth One end of the capacitor is connected, the other end of the fourth capacitor is grounded, the second switch is closed to cause the power source to charge the fourth capacitor, and the second switch is turned off to disconnect the power source Charging of the fourth capacitor.
  • the control module includes a third switch, a fourth switch, a fifth switch, and a sixth switch; and one end of the third switch Connected to one end of the third capacitor, the other end of the third switch is connected to the first capacitor, the fifth switch is connected in parallel with the first capacitor; one end of the fourth switch is One end of the fourth capacitor is connected, the other end of the fourth switch is connected to the second capacitor, and the sixth switch is connected in parallel with the second capacitor; in the first stage, the third switch is off When the fifth switch is closed, the first capacitor is discharged to the amount of charge at both ends until the amount of charge across the first capacitor is zero; in the first phase, the fourth switch is turned off and When the sixth switch is closed, discharging the second capacitor to a charge amount of zero at the second capacitor; in the second phase, the charging module is disconnected from charging, and the third switch is closed and The fifth switch is disconnected Causing the third capacitor to discharge to the first capacitor; in the second phase
  • the charging module is a power source
  • the control module includes a seventh switch, an eighth switch, a ninth switch, and a tenth switch; a first end of the seventh switch is connected to the power source, a second end of the seventh switch is connected to a first end of the third capacitor, and a second end of the seventh switch is opposite to the fourth end a first end of the capacitor is also connected, a first end of the eighth switch is grounded, a second end of the eighth switch is connected to a first end of the third capacitor, and a second end of the eighth switch is a first end of the fourth capacitor is connected; the ninth switch is connected in parallel with the first capacitor, and the tenth switch is connected in parallel with the second capacitor; in the first stage, the seventh The switch is closed, the ninth switch and The tenth switch is closed, and when the eighth switch is turned off, the power source is charged to the third capacitor and the fourth capacitor, and the first capacitor and the second capacitor are discharged to The amount of charge at both ends is zero; in
  • a pressure detecting system comprising a pressure detecting module, at least one capacitance detecting device according to any one of the first aspects, at least one of the third capacitor, and at least a fourth capacitor, wherein each capacitance detecting device corresponds to a third capacitor to be tested and a fourth capacitor to be tested, and the pressure detecting module is configured to calculate a capacitance according to the at least one of the third capacitors A difference from a capacitance of the at least one of the fourth capacitors results in a detected pressure.
  • the pressure detecting system further includes a display screen and a middle frame
  • the third capacitor and the fourth capacitor are self-capacitors
  • the at least one of the third a detecting electrode of the capacitor and a detecting electrode of the at least one of the fourth capacitors are located between a display screen and a middle frame, a gap between the detecting electrode of the third capacitor and the middle frame, the fourth capacitor There is a gap between the detecting electrode and the middle frame.
  • the third capacitor and the fourth capacitor may be mutual capacitance.
  • the gaps may be filled with air or may be filled with an elastic material.
  • the third capacitor and the fourth capacitor may be located in the same terminal device.
  • a capacitance detecting method is provided, the method being performed by a capacitance detecting device including a differential amplifier, a first capacitor, a second capacitor, a charging module, a control module, and a calculation module, the difference
  • the amplifier includes a first input, a second input, a first output, and a second output, the first input being coupled to the third capacitor to be tested, the second input and the fourth to be tested
  • the capacitors are connected, the method includes: in the first stage, controlling, by the control module, the third capacitor to be tested and the fourth capacitor to be tested by the charging module, and controlling the first capacitor and the The second capacitor performs discharging; in the second stage, the charging module controls the charging module to disconnect charging of the third capacitor and the fourth capacitor, and controls the third capacitor to the first Discharging a capacitor and controlling the fourth capacitor to discharge to the second capacitor; amplifying and amplifying the signal by the differential amplifier Outputting from the first output end and the second output end to the calculation module; according to the calculation module, according to the calculation
  • the two capacitors to be tested can be charged, and then the charge amount of the capacitor to be tested is transferred to the capacitor in the capacitance detecting circuit, and the voltage discharged by the capacitor to be tested is amplified and output to the calculation module through the differential amplifier.
  • the voltage difference of the output of the differential amplifier can be used to detect the difference of the capacitance of the different capacitors, which can realize the detection of the large capacitance with a small capacitance, and can improve the accuracy of the pressure detection by the capacitance detection of the present invention.
  • the capacitance detecting apparatus further includes a first variable capacitor and a second variable capacitor, wherein the first variable capacitor and the third capacitor are connected in parallel The second variable capacitor and the fourth capacitor are connected in parallel.
  • the method further includes: adjusting the first capacitor and the fourth capacitor before the capacitance value of the third capacitor and the fourth capacitor are changed by the outside world a capacitance of a variable capacitor and the second variable capacitor such that a sum of a capacitance of the first variable capacitor and a capacitance of the third capacitor is equal to a capacitance of the second variable capacitor and a fourth capacitor The sum of the capacitors.
  • the capacitance detecting apparatus further includes a first variable resistor and a second variable resistor, the first variable resistor and the The first capacitors are connected in parallel, and the second variable resistor and the second capacitor are connected in parallel.
  • the capacitance detecting method of the embodiment of the present invention may correspond to each unit/module in the capacitance detecting device of the first aspect of the present invention, and the corresponding flow in the method may pass through the first aspect of the capacitance detecting device.
  • Each unit/module is implemented, and for brevity, it will not be described here.
  • FIG. 1 is a schematic diagram of a capacitance detecting device according to an embodiment of the present invention.
  • FIG. 2 is a circuit diagram of a capacitance detecting device according to an embodiment of the present invention.
  • FIG. 3 is a circuit diagram of a capacitance detecting device according to another embodiment of the present invention.
  • FIG. 4 is a circuit diagram of a capacitance detecting device according to still another embodiment of the present invention.
  • Fig. 5 is a circuit diagram showing a capacitance detecting device according to still another embodiment of the present invention.
  • Figure 6 is a schematic illustration of a pressure sensing system constructed using a capacitance detecting device in accordance with one embodiment of the present invention.
  • Fig. 7 is a schematic diagram of a pressure detecting system constructed using a capacitance detecting device according to another embodiment of the present invention.
  • FIG. 8 is a schematic flow chart of a capacitance detecting method according to an embodiment of the present invention.
  • FIG. 1 is a schematic diagram of a capacitance detecting device according to an embodiment of the present invention.
  • the capacitance detecting device 10 shown in FIG. 1 includes a control module 11, a charging module 12, a calculation module 13, a differential amplifier 14, a first capacitor 15, and a second capacitor 16.
  • the two capacitors (such as the third capacitor and the fourth capacitor) to be tested by the charging module may be controlled by the control module, and the first capacitor and the second capacitor are controlled to be discharged by the control module, so that the first capacitor and the first capacitor The amount of charge at both ends of the capacitor is zero.
  • the charges of the charged third capacitor and the fourth capacitor are transferred to the first capacitor and the second capacitor.
  • the voltage at one end of the third capacitor and the voltage at one end of the fourth capacitor are input to the differential amplifier, and two voltages are obtained at the two output ports of the differential amplifier.
  • the transferred charge transfer coefficient, the capacitance of the first capacitor, and the capacitance of the second capacitor are the difference between the capacitance of the third capacitor and the capacitance of the fourth capacitor.
  • the two capacitors to be tested can be charged, and then the charge amount of the capacitor to be tested is transferred to the capacitor in the capacitance detecting circuit, and the voltage discharged by the capacitor to be tested is amplified and output to the calculation module through the differential amplifier. In this way, the voltage difference calculation of the output of the differential amplifier can be used to detect the difference in capacitance of different capacitors.
  • the capacitance detecting device may further include a first variable capacitor and a second variable capacitor.
  • the first variable capacitor and the third capacitor are connected in parallel
  • the second variable capacitor and the fourth capacitor are connected in parallel
  • the sum of the capacitance of the first variable capacitor and the capacitance of the third capacitor is equal to that of the second variable capacitor The sum of the capacitance of the capacitor and the fourth capacitor.
  • the capacitance detecting device may further include a first variable resistor and a And a second variable resistor, the first variable resistor and the first capacitor are connected in parallel, and the second variable resistor and the second capacitor are connected in parallel.
  • the capacitance detecting device may cause a change in temperature due to energization, so that the capacitance of the capacitor changes.
  • the embodiment of the invention can detect the capacitance difference between the two capacitors. By arranging the two capacitors in the same plane and the distance between the two capacitors is close to each other, the temperature change can be simultaneously fed back to the two capacitors to be detected. Moreover, the temperature change is equivalent to the change or influence caused by the two capacitors to be detected. At this time, the differential processing can cancel the effects caused by the temperature changes, thereby suppressing the temperature drift.
  • the capacitance detecting device in the embodiment of the present invention can simulate the pressure writing experience according to the detected capacitance change when the capacitive active pen pressure of the capacitive touch screen is different, so that the capacitive active pen can be more accurately obtained. Input can greatly enhance the user experience.
  • the capacitance detecting device in the embodiment of the present invention can also recognize the pressure of the finger by detecting the difference of the capacitance by detecting the difference of the capacitance, thereby improving the user experience.
  • the capacitance detecting device in the embodiment of the present invention can also obtain the pressure on the screen of the mobile phone by detecting the difference of the capacitance, thereby turning the screen of the mobile phone into a high-precision electronic scale, thereby improving the pressure application scenario of the mobile phone and optimizing the pressure user experience. .
  • FIG. 2 is a circuit diagram of a capacitance detecting device according to an embodiment of the present invention.
  • the third capacitor 207 and the fourth capacitor 208 are capacitors to be detected.
  • the third capacitor and the fourth capacitor in the embodiment of the invention are self-capacitance.
  • the circuit of the capacitance detecting device includes a control module, a first capacitor 209, a second capacitor 210, a charging module 211, a differential amplifier 212, and a calculation module 213.
  • the control module includes a first switch 201, a second switch 202, a third switch 203, a fourth switch 204, a fifth switch 205, and a sixth switch 206.
  • the charging module 211 can be a power source.
  • One end of the first switch 201 is connected to the power source 211, the other end of the first switch 201 is connected to one end of the third capacitor 207, and the other end of the third capacitor 207 is grounded.
  • One end of the second switch 202 is connected to the power source 211, the other end of the second switch 202 is connected to one end of the fourth capacitor 208, and the other end of the fourth capacitor 208 is grounded.
  • One end of the third switch 203 is connected to one end of the third capacitor 207, and the other end of the third switch 203 is connected to the first capacitor 209.
  • the fifth switch 205 is connected in parallel with the first capacitor 209.
  • the sixth switch 206 is connected in parallel with the second capacitor 210.
  • the differential amplifier includes a first input, a second input, a first output, and a second output.
  • the first input of the differential amplifier 212 (as it is to the input) is coupled to the third capacitor 207 via a third switch 203.
  • a second input of differential amplifier 212 such as an inverting input, is coupled to fourth capacitor 208 via fourth switch 204.
  • the two output ports of the differential amplifier are connected to the calculation module 213.
  • a first input end of the differential amplifier is connected to the third capacitor to be tested, and a second input end is connected to the fourth capacitor to be tested, and the first input end and the first output end are respectively connected to the two ends of the first capacitor, The second input end and the second output end are respectively connected to both ends of the second capacitor, and the first output end and the second output end are both connected to the calculation module.
  • the two capacitors to be tested can be charged, and then the charge amount of the capacitor to be tested is transferred to the capacitor in the capacitance detecting circuit, and amplified by the differential amplifier and the amplified signal is output to the calculation module, and thus The capacitance difference of the different capacitors can be detected by the voltage calculation at the output of the differential amplifier.
  • the first stage is the charge reset phase, the capacitor to be tested is charged, and both the first capacitor 209 and the second capacitor 210 are discharged until the amount of charge is zero.
  • the first switch 201 and the second switch 202 may be closed, the third switch 203 and the fourth switch 204 are turned off, and the fifth switch 205 and the sixth switch 206 are closed.
  • the power source 211 charges the third capacitor 207 and the fourth capacitor 208, and charges to V.
  • the fifth switch 205 and the sixth switch 206 are closed, and the first capacitor 209 and the second capacitor 210 are connected by wires at both ends, and the voltages across the first capacitor 209 and the second capacitor 210 are discharged to a common mode voltage, and the first capacitor is two.
  • the voltage at the terminal is zero, the voltage across the second capacitor is also zero, and the amount of charge across the first capacitor and the second capacitor is also zero.
  • the second phase is a discharge detecting phase, and the amount of charge after charging the third capacitor 207 to be tested and the fourth capacitor 208 to be tested is transferred to the first capacitor 209 and the second capacitor 210.
  • the first switch and the second switch may be turned off, the third switch and the fourth switch are closed, and the fifth switch and the sixth switch are turned off.
  • the power source 211 turns off the charging of the third capacitor 207 and the fourth capacitor 208.
  • the third capacitor 207 and the fourth capacitor 208 are respectively discharged to the two input terminals of the differential amplifier 212, and the amount of charge across the third capacitor 207 and the fourth capacitor 208 are two.
  • the amount of charge at the terminals is transferred to the first capacitor 209 and the second capacitor 210, respectively.
  • the capacitances of the third capacitor to be tested and the fourth capacitor to be tested are denoted as C x1 and C x2 , respectively, and the capacitance values of different capacitors to be tested may cause the two outputs of the differential amplifier.
  • the voltages are different, and V out+ and V out- respectively represent the voltages of the two output terminals of the differential amplifier, and C fb1 and C fb2 respectively represent the capacitance values of the first capacitor and the second capacitor, k is the charge transfer coefficient, and the first to be tested
  • the charge transfer coefficient k (C fb -0.5*C fb -0.5*C x1 /(C fb +C x1 ).
  • the charge transfer coefficient k (C fb -0.5 * C fb -0.5 * C x2 ) / (C fb + C x2 ).
  • the capacitance difference between the third capacitor to be tested and the fourth capacitor to be tested When C fb1 and C fb2 are set to the same value, the circuit operation can be made simple, so that the capacitance detection sensitivity can be higher.
  • the capacitance values of the first capacitor and the second capacitor in the capacitance detecting device are not limited, and the detection of the large capacitance can be realized by using a small capacitor.
  • the capacitances of the first capacitor and the second capacitor are small, the same It is possible to detect the capacitances of the third capacitor and the fourth capacitor having a large capacitance value. In this way, the chip area in the circuit of the capacitance detecting device can be saved.
  • the embodiment of the present invention does not limit the power supply voltage of the charging module.
  • the capacitor to be tested can be charged with a lower voltage.
  • FIG. 3 is a circuit diagram of a capacitance detecting device according to another embodiment of the present invention.
  • the third capacitor 307 and the fourth capacitor 308 in Fig. 3 are capacitors to be detected.
  • the circuit of the capacitance detecting device includes: a control module, a first capacitor 309, a second capacitor 310, a charging module 311, a differential amplifier 312, a calculation module 313, a first variable capacitor 314, a second variable capacitor 315, and a first variable A resistor 316 and a second variable resistor 317.
  • the control module includes a first switch 301, a second switch 302, a third switch 303, a fourth switch 304, a fifth switch 305, and a sixth switch 306.
  • the devices and modules 301-313 in FIG. 3 and the devices and modules corresponding to 201-213 in FIG. 2 are connected in the same manner, and have the same functions, and are not described in detail.
  • two variable capacitors may be added to the circuit of FIG. 2, such as first variable capacitor 314 and second variable capacitor 315 in FIG.
  • first variable capacitor 314 and the third capacitor 307 are connected in parallel
  • the second variable capacitor 315 and the fourth capacitor 308 are connected in parallel
  • the sum of the capacitance of the first variable capacitor 314 and the capacitance of the third capacitor 307 is equal to the first The sum of the capacitance of the second variable capacitor 315 and the capacitance of the fourth capacitor 308.
  • the capacitance of the capacitor to be tested is equal when there is no pressure, but due to manufacturing errors, the difference between the capacitance values of the two capacitors to be tested when there is no pressure may not be zero, and this difference may cause the output of the differential amplifier 312 to have The voltage, which occupies the dynamic range of the circuit, affects the sensitivity of the circuit.
  • variable capacitors 314 and 315 by adding variable capacitors 314 and 315 and adjusting the capacitance of the variable capacitor when there is no pressure, the sum of the capacitance of the first variable capacitor 314 and the capacitance of the third capacitor 307 is equal to the second The sum of the capacitance of the variable capacitor 315 and the capacitance of the fourth capacitor 308, so that when there is no pressure, the output of the differential amplifier 312 can be made to have no voltage output, which can improve the measurement sensitivity when the pressure is applied.
  • two variable resistors may be added to the circuit of FIG. 2, such as the first variable resistor 316 and the second variable resistor 317 in FIG.
  • the first variable resistor 316 and the first capacitor 309 are connected in parallel, and the second variable resistor 317 and the second capacitor 310 are connected in parallel.
  • the frequency response of the circuit can be controlled, and the interference can be prevented in an interference environment, thereby improving the signal-to-noise ratio.
  • the first variable resistor and the second variable resistor may be set to have the same resistance value at the same time, and the assumption is denoted as R, the circuit operating frequency.
  • R the circuit operating frequency
  • FIG. 4 is a circuit diagram of a capacitance detecting device according to still another embodiment of the present invention.
  • the third capacitor 404 and the fourth capacitor 405 in FIG. 4 are capacitors to be detected.
  • the third capacitor 404 and the fourth capacitor 405 may be mutual capacitances.
  • the circuit of the capacitance detecting device includes a control module, a first capacitor 407, a second capacitor 408, a charging module 401, a differential amplifier 410, and a calculation module 411.
  • the control module includes a seventh switch 402, an eighth switch 403, a ninth switch 406, and a tenth switch 409.
  • the charging module 401 can be a power source.
  • One end of the seventh switch 402 is connected to the power source 401, and one end of the eighth switch 403 is grounded, and the other end is connected to one ends of the two capacitors 404 and 405 to be tested.
  • the two other ends of the two capacitors to be tested are respectively connected to the two input terminals of the differential amplifier 410, and the two outputs of the differential amplifier 410 are connected to the calculation module 411.
  • the two ends of the first capacitor 407 are respectively connected to one input terminal of the differential amplifier 410 (such as the same input terminal in FIG. 4) and one output terminal (such as Vout- in FIG. 4), and the two ends of the second capacitor 408 are respectively The other input of differential amplifier 410 (reverse in Figure 4) The input is connected to another output (Vout+ in Figure 4).
  • the ninth switch 406 is connected in parallel with the first capacitor 407, and the tenth switch 409 is connected in parallel with the second capacitor 408.
  • the two capacitors to be tested can be charged, and then the charge amount of the capacitor to be tested is transferred to the capacitor in the capacitance detecting circuit, and the voltage discharged by the capacitor to be tested is amplified and output to the calculation module through the differential amplifier. In this way, the voltage difference calculation of the output of the differential amplifier can be used to detect the difference in capacitance of different capacitors.
  • the circuit is in a reset state, and the voltages across the first capacitor 407 and the second capacitor 408 are discharged to zero.
  • the voltages of the two outputs of the differential amplifier 410 are equal, that is, the voltage difference at the output is zero.
  • the first stage is the charging phase, and the capacitor to be tested is charged. Specifically, the seventh switch 402 is closed, the eighth switch 403 is turned off, the ninth switch 406 is turned off, and the tenth switch 409 is turned off. At this time, the power source 401 charges the third capacitor 404 and the fourth capacitor 405, and both are charged to Voltage V.
  • the second phase is a discharge phase, and the amount of charge after charging the third capacitor 404 to be tested and the fourth capacitor 405 to be tested is transferred to the first capacitor 407 and the second capacitor 408.
  • the seventh switch 402 can be turned off, the eighth switch 403 is closed, the ninth switch 406 is turned off, and the tenth switch 409 is turned off.
  • the switch 407 and the switch 408 can be turned off, and one of the switch 402 and the switch 403 is turned on, and one is turned off and alternately performed, so that charging and discharging can be alternately performed.
  • the capacitances of the third capacitor to be tested and the fourth capacitor to be tested are denoted as C x1 and C x2 , respectively, and the capacitance values of different capacitors to be tested may cause the two outputs of the differential amplifier.
  • the voltages are different, and V out+ and V out- respectively represent the voltages of the two output terminals of the differential amplifier, and C fb1 and C fb2 respectively represent the capacitance values of the first capacitor and the second capacitor, k is the charge transfer coefficient, and the first to be tested
  • the charge transfer coefficient k (C fb -0.5*C fb -0.5*C x1 /(C fb +C x1 ).
  • the charge transfer coefficient k (C fb -0.5 * C fb -0.5 * C x2 ) / (C fb + C x2 ).
  • Fig. 5 is a circuit diagram showing a capacitance detecting device according to still another embodiment of the present invention.
  • the third capacitor 504 and the fourth capacitor 505 in FIG. 5 are capacitors to be detected.
  • the circuit of the capacitance detecting device includes: a control module, a first capacitor 507, a second capacitor 508, a charging module 501, a differential amplifier 510, a calculation module 511, a first variable capacitor 512, a second variable capacitor 513, and a first variable A resistor 514 and a second variable resistor 515.
  • the control module includes a seventh switch 502, an eighth switch 503, a ninth switch 506, and a tenth switch 509.
  • the device and the module 501-411 in FIG. 5 and the device and module corresponding to 401-411 in FIG. 4 are connected in the same manner, and have the same functions, and are not described in detail.
  • two variable capacitors may be added to the circuit of FIG. 4, such as first variable capacitor 512 and second variable capacitor 513 in FIG.
  • first variable capacitor 512 and the third capacitor 504 are connected in parallel
  • second variable capacitor 513 and the fourth capacitor 505 are connected in parallel
  • the sum of the capacitance of the first variable capacitor 512 and the capacitance of the third capacitor 504 is equal to the first The sum of the capacitance of the second variable capacitor 513 and the capacitance of the fourth capacitor 505.
  • the capacitance of the capacitor to be tested is equal when there is no pressure, but due to manufacturing errors, the difference between the capacitance values of the two capacitors to be tested may be not zero when there is no pressure, and this difference may cause the output of the differential amplifier. There is voltage, which occupies the dynamic range of the circuit and affects the sensitivity of the circuit.
  • the capacitance detecting device in the embodiment of the present invention can be applied to a mobile phone for detecting the pressure applied to the display screen of the mobile phone according to the difference in capacitance, and used on the active pen to calculate the difference according to the capacitance.
  • the variable capacitor can be increased, and the capacitance of the variable capacitor can be adjusted when there is no pressure, so that the sum of the capacitance of the first variable capacitor and the capacitance of the third capacitor is equal to the capacitance of the second variable capacitor.
  • the capacitance of the fourth capacitor so that when there is no pressure, the output of the differential amplifier has no voltage output, which can improve the measurement sensitivity when there is pressure.
  • two variable resistors may be added to the circuit of FIG. 4, such as the first variable resistor 514 and the second variable resistor 515 in FIG.
  • the first variable resistor and the first capacitor are connected in parallel, and the second variable resistor and the second capacitor are connected in parallel.
  • the frequency response of the circuit can be controlled, and the interference can be prevented in an interference environment, thereby improving the signal-to-noise ratio.
  • the first variable resistor and the second variable resistor may be set to have the same resistance value, and all are assumed to be R, and the circuit operating frequency is When f can be set, R needs to meet the following conditions:
  • FIG. 6 and FIG. 7 are described by taking a mobile phone pressure detection example as an example.
  • Figure 6 is a schematic illustration of a pressure sensing system constructed using a capacitance detecting device in accordance with one embodiment of the present invention.
  • the pressure detecting system includes at least one capacitance detecting device 200, a mobile phone display screen 601, a detecting electrode of the capacitor to be detected, and a pressure detecting module 602.
  • the capacitor to be detected includes C1, C2, C3, C4, C5, C6, C7, and C8.
  • the capacitor to be detected in one embodiment of the present invention may be a self-capacitance. One end of the capacitor to be detected is grounded, and the other end is a detecting electrode.
  • the detecting electrode may be located between the display screen and the middle frame, and has a gap between the detecting electrode and the middle frame. For example, the detection electrode can be attached to the back of the display.
  • Each of the capacitance detecting devices 200 connects two detecting electrodes to be detected, and detects a capacitance difference between the two capacitors.
  • C1, C2, C3, C4 may be placed in the middle, and C5, C6, C7, C8 may be placed on the corners.
  • the capacitance to the ground changes little, and the capacitance between the intermediate capacitor and the capacitor on the corner is poor, so that the capacitance difference between the two capacitors can be obtained.
  • the capacitance difference of the capacitors in the same environment it is possible to reduce the change in capacitance due to changes in the external environment. For example, when the ambient temperature or humidity is different, the capacitance of the same capacitor in the same state may be different.
  • the difference between the two capacitances can be prevented by one embodiment of the present invention to prevent the drift of the capacitance value caused by the change in temperature or humidity or the like.
  • the detecting electrode may be attached to the back of the display screen, and the detecting electrode has a certain gap with the middle frame, and the gap may be filled with air or may be filled with an elastic material.
  • the number of the capacitance detecting devices 200 may be one or more.
  • Fig. 6 four capacitance detecting devices are taken as an example for description.
  • the capacitance detecting device 200 may have a circuit diagram as shown by 200 in FIG. 2, and may also add a variable capacitor and/or a variable resistor based on 200, as shown in FIG.
  • the circuit diagram shown in 300 may be an example of the detecting device shown in Fig. 2.
  • the pressure detecting module 602 in the embodiment of the present invention can obtain the pressure to be detected according to the capacitance difference obtained by the capacitance detecting device.
  • Fig. 7 is a schematic diagram of a pressure detecting system constructed using a capacitance detecting device according to another embodiment of the present invention.
  • the pressure detecting system includes at least one capacitance detecting device 400, a mobile phone display screen 701, a middle frame 702, two electrodes 703 to be detected, and a pressure detecting module 704.
  • the capacitor to be detected includes C1, C2, C3, C4, C5, C6, C7, and C8.
  • Each capacitor to be tested includes two electrodes, and both electrodes are located between the display screen of the mobile phone and the middle frame.
  • Each capacitance detecting device 400 is for detecting a capacitance difference between two capacitors.
  • C1, C2, C3, C4 may be placed in the middle, and C5, C6, C7, C8 may be placed on the corners.
  • the capacitance changes obviously.
  • the capacitance changes little, and the capacitance between the intermediate capacitor and the capacitor on the corner is poor, so that the capacitance difference between the two capacitors can be obtained.
  • the capacitance difference of the capacitors in the same environment it is possible to reduce the change in capacitance due to changes in the external environment. For example, when the ambient temperature or humidity is different, the capacitance of the same capacitor in the same state may be different.
  • the difference between the two capacitors can be prevented by the embodiment of the present invention to prevent the drift of the capacitance value caused by the change in temperature or humidity or the like.
  • two electrodes of the capacitor to be detected may be attached to the back of the display screen, and one of the electrodes may be attached to the middle frame such that a certain gap is formed between the two electrodes.
  • the gap can be filled with air or filled with an elastic material.
  • the capacitance detecting device 400 may have a circuit diagram as shown by 400 in FIG. 4, and may also add a variable capacitor and/or a variable resistor based on 400, as shown in FIG. The circuit diagram shown. What is shown in Fig. 7 is an example in which the capacitance detecting means is the detecting means shown in Fig. 4.
  • the pressure detecting module 704 in the embodiment of the present invention can obtain the pressure to be detected according to the capacitance difference obtained by the capacitance detecting device.
  • FIG. 8 is a schematic flow chart of a capacitance detecting method according to an embodiment of the present invention.
  • the capacitance detecting method of the embodiment of the present invention can be performed by a capacitance detecting device.
  • Capacitance detection device can include differential placement The amplifier, the first capacitor, the second capacitor, the charging module, the control module, and the calculation module.
  • the differential amplifier includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal is connected to the third capacitor to be tested, and the second input terminal is connected to the fourth capacitor to be tested.
  • the specific flow of the capacitance detection method is as follows.
  • control module controls the charging module to charge the third capacitor to be tested and the fourth capacitor to be tested, and controls discharging of the first capacitor and the second capacitor.
  • the charging module is controlled by the control module to disconnect the charging of the third capacitor and the fourth capacitor, control the third capacitor to discharge to the first capacitor, and control the fourth capacitor to discharge to the second capacitor.
  • the difference between the capacitance of the third capacitor and the capacitance of the fourth capacitor is obtained by the calculation module according to the power supply voltage of the charging module, the voltage of the first output terminal, the voltage of the second output terminal, the capacitance of the first capacitor, and the capacitance of the second capacitor.
  • the two capacitors to be tested can be charged, and then the charge amount of the capacitor to be tested is transferred to the capacitor in the capacitance detecting circuit, and the amplified signal is output to the calculation module through differential amplifier amplification, and then passed.
  • the voltage calculation at the output of the differential amplifier enables the detection of the difference in capacitance of different capacitors.
  • the capacitance detecting method according to the embodiment of the present invention may correspond to each unit/module in the capacitance detecting apparatus of the embodiment of the present invention, and the corresponding flow in the method may pass through each of the apparatuses shown in FIGS. 1 to 7.
  • the unit/module is implemented, and for brevity, it will not be described here.
  • the size of the sequence numbers of the above processes does not mean the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not be taken to the embodiments of the present invention.
  • the implementation process constitutes any limitation.
  • B corresponding to A means that B is associated with A, and B can be determined according to A. But it should also be understood that determining B according to A does not mean that it is only determined according to A. B, B can also be determined based on A and/or other information.
  • system and “network” are used interchangeably herein. It should be understood that the term “and/or” herein is merely an association relationship describing an associated object, indicating that there may be three relationships, for example, A and/or B, which may indicate that A exists separately, and A and B exist simultaneously. There are three cases of B alone. In addition, the character "/" in this article generally indicates that the contextual object is an "or" relationship.
  • the disclosed systems, devices, and methods may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in an electrical, mechanical or other form.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.
  • each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the storage medium referred to herein may include: a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.
  • the medium of the program code may include: a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

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Abstract

一种电容检测装置方法和压力检测系统。电容检测装置（10）包括差分放大器（14）、第一电容器（15）、第二电容器（16）、充电模块（12）、控制模块（11）和计算模块（13），差分放大器（14）包括第一输入端、第二输入端、第一输出端和第二输出端，通过控制模块（11）控制充电模块（12）对待测两个电容器充电，将待测的电容器的电荷量向第一电容器（15）和第二电容器（16）转移，并通过差分放大器（14）放大并将放大后的信号输出到计算模块（13），这样通过差分放大器（14）的输出端的电压、充电模块（12）的供电电压、第一电容器（15）的电容和第二电容器（16）的电容可以计算得到不同电容器的电容差值。

Description

电容检测装置、方法和压力检测系统 技术领域
本发明实施例涉及触控技术领域，并且更具体地，涉及电容检测装置、方法和压力检测系统。
背景技术
触控技术应用在智能终端上，可以让使用者只要通过手势操作即可实现终端的操作，摆脱了传统的机械键盘，使人机交互更为直截了当。
但是，随着触控技术的发展，触控技术已不能满足用户更多维度输入的需求。例如，在电容触摸屏中加入电容主动笔，电容主动笔触压触摸屏，压力发生改变，但触摸屏无法根据压力的改变进行不同的书写操作。又如，在传统的按键或指纹识别的基础上，也没有根据按键或指纹压力的改变给出不同的操作。这样，通过触控技术很难模拟真笔书写的体验，影响输入的准确性，用户体验效果不佳。
应上述压力需求，要提高用户体验，需要检测屏幕的压力大小。手机屏幕上压力的改变，使得手机里两个电极片之间的距离以及电容发生改变，故可以通过检测电容器的电容得到用户压力信息。本发明提出一种检测两个电容器的电容差的电容检测装置。
发明内容
本发明实施例提供一种电容检测装置、方法和压力检测系统，能够用小电容实现大电容的检测、能提升利用本发明的电容检测实现压力检测时的准确性。
第一方面，本发明提供了一种电容检测装置，所述装置包括差分放大器、第一电容器、第二电容器、充电模块、控制模块和计算模块，所述差分放大器包括第一输入端、第二输入端、第一输出端和第二输出端；所述第一输入端和待测的第三电容器相连接，所述第二输入端和待测的第四电容器相连接，所述第一输入端和所述第一输出端分别与所述第一电容器的两端连接，所述第二输入端和所述第二输出端分别与所述第二电容器的两端连接，所述第一输出端和所述第二输出端都与所述计算模块相连接；在第一阶段，所述 控制模块用于控制所述充电模块对所述第三电容器和所述第四电容器进行充电，所述控制模块还用于控制所述第一电容器和所述第二电容器进行放电；在第二阶段，所述控制模块用于控制所述充电模块断开对所述第三电容器和所述第四电容器的充电，所述控制模块还用于控制所述第三电容器向所述第一电容器放电，并控制所述第四电容器向所述第二电容器放电；所述差分放大器用于放大并将放大后的信号从所述第一输入端和所述第二输入端输出到所述计算模块；所述计算模块用于根据所述充电模块的供电电压、所述第一输出端的电压、所述第二输出端的电压、所述第一电容器的电容和所述第二电容器的电容得到所述第三电容器的电容和所述第四电容器的电容的差。
本发明实施例可以通过对待测的两个电容器充电，然后将待测的电容器的电荷量向电容检测电路中的电容器转移，并通过差分放大器将待测电容器放电后的电压放大输出到计算模块，这样再通过差分放大器的输出端的电压计算可以实现不同电容器的电容差的检测。
利用本发明实施例的电容检测可以实现压力检测，这样能够提升检测灵敏度，可以使得用户体验效果更佳。
结合第一方面，在第一方面的一种实现方式中，所述装置还包括第一可变电容器和第二可变电容器，所述第一可变电容器和所述第三电容器并联连接，所述第二可变电容器和所述第四电容器并联连接。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，在所述第三电容器和第四电容器的电容值被外界改变之前，所述第一可变电容器的电容和所述第三电容器的电容之和等于所述第二可变电容器的电容和所述第四电容器的电容之和。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，所述电容检测装置还包括第一可变电阻和第二可变电阻，所述第一可变电阻和所述第一电容器并联连接，所述第二可变电阻和所述第二电容器并联连接。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，同一时间，所述第一可变电阻的电阻值和所述第二可变电阻的电阻值相同。
优选地，在同一时间两个可变电阻的电阻值可以相同，这样，对称的电路设计可以使得电路的灵敏度更好。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，所 述第一电容器的电容和所述第二电容器的电容相同。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，所述充电模块为电源；所述控制模块包括第一开关和第二开关；第一开关的一端与所述电源连接，所述第一开关的另一端与所述第三电容器的一端连接，所述第三电容器的另一端接地，所述第一开关闭合时使得所述电源对所述第三电容器充电，所述第一开关断开时用于断开所述电源对所述第三电容器的充电；所述第二开关的一端与所述电源连接，所述第二开关的另一端与所述第四电容器的一端连接，所述第四电容器的另一端接地，所述第二开关闭合时使得所述电源对所述第四电容器充电，所述第二开关断开时用于断开所述电源对所述第四电容器的充电。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，所述控制模块包括第三开关，第四开关、第五开关和第六开关；所述第三开关的一端与所述第三电容器的一端连接，所述第三开关的另一端与所述第一电容器连接，所述第五开关与所述第一电容器并联连接；所述第四开关的一端与所述第四电容器的一端连接，所述第四开关的另一端与所述第二电容器连接，所述第六开关与所述第二电容器并联连接；在所述第一阶段，所述第三开关断开且所述第五开关闭合时，使得所述第一电容器放电到两端电荷量至所述第一电容器两端电荷量为零；在所述第一阶段，所述第四开关断开且所述第六开关闭合时，使得所述第二电容器放电至所述第二电容器两端电荷量零；在所述第二阶段，所述充电模块断开充电，所述第三开关闭合且所述第五开关断开时，使得所述第三电容器向所述第一电容器放电；在所述第二阶段，所述充电模块断开充电，所述第四开关闭合且所述第六开关断开时，使得所述第四电容器向所述第二电容器放电。
结合第一方面及其上述实现方式，在第一方面的另一种实现方式中，所述充电模块为电源；所述控制模块包括第七开关、第八开关、第九开关和第十开关；所述第七开关的第一端与所述电源连接，所述第七开关的第二端与所述第三电容器的第一端连接，所述第七开关的第二端与所述第四电容器的第一端也连接，所述第八开关的第一端接地，所述第八开关的第二端与所述第三电容器的第一端连接，所述第八开关的第二端与所述第四电容器的第一端连接；所述第九开关与所述第一电容器并联连接，所述第十开关与所述第二电容器并联连接；在所述第一阶段，所述第七开关闭合、所述第九开关和 所述第十开关都闭合，且所述第八开关断开时，使得所述电源对所述第三电容器和所述第四电容器充电，所述第一电容器和所述第二电容器都放电到两端电荷量为零；在所述第二阶段，所述第七开关、所述第九开关和所述第十开关都断开，且所述第八开关闭合时，使得所述第三电容器向所述第一电容器放电，且所述第四电容器向所述第二电容器放电。
第二方面，提供了一种压力检测系统，所述压力检测系统包括压力检测模块、至少一个如第一方面中任一种实现方式所述的电容检测装置、至少一个所述第三电容器和至少一个所述第四电容器，其中，每个电容检测装置对应一个待测的第三电容器和一个待测的第四电容器，所述压力检测模块用于根据所述至少一个所述第三电容器的电容和所述至少一个所述第四电容器的电容的差得到被检测的压力。
结合第二方面，在第二方面的一种实现方式中，所述压力检测系统还包括显示屏和中框，所述第三电容器及第四电容器为自电容，所述至少一个所述第三电容器的检测电极和所述至少一个所述第四电容器的检测电极位于显示屏和中框之间，所述第三电容器的检测电极和所述中框之间具有间隙，所述第四电容器的检测电极和所述中框之间具有间隙。
在本发明的另一个实施例中，第三电容器和第四电容器可以为互电容。
在本发明的一个实施例中，上述间隙之间可以填充空气，也可以填充弹性材料。
在本发明的一个实施例中，第三电容器和第四电容器可以位于同一个终端设备。
第三方面，提供了一种电容检测方法，所述方法由电容检测装置执行，所述电容检测装置包括差分放大器、第一电容器、第二电容器、充电模块、控制模块和计算模块，所述差分放大器包括第一输入端、第二输入端、第一输出端和第二输出端，所述第一输入端和待测的第三电容器相连接，所述第二输入端和待测的第四电容器相连接，所述方法包括：在第一阶段，通过所述控制模块控制所述充电模块对待测的第三电容器和待测的第四电容器进行充电，并控制对所述第一电容器和所述第二电容器进行放电；在第二阶段，通过所述控制模块控制所述充电模块断开对所述第三电容器和所述第四电容器的充电，控制所述第三电容器向所述第一电容器放电，并控制所述第四电容器向所述第二电容器放电；通过所述差分放大器放大并将放大后的信号 从所述第一输出端和所述第二输出端输出到所述计算模块；通过所述计算模块根据所述充电模块的供电电压、所述第一输出端的电压、所述第二输出端的电压、所述第一电容器的电容和所述第二电容器的电容得到所述第三电容器的电容和所述第四电容器的电容的差。
本发明实施例可以通过对待测的两个电容器充电，然后将待测的电容器的电荷量向电容检测电路中的电容器转移，并通过差分放大器将待测电容器放电后的电压放大输出到计算模块，这样再通过差分放大器的输出端的电压计算可以实现不同电容器的电容差的检测，其可以用小电容实现大电容的检测、能提升利用本发明的电容检测实现压力检测时的准确性。
结合第三方面，在第三方面的一种实现方式中，所述电容检测装置还包括第一可变电容器和第二可变电容器，所述第一可变电容器和所述第三电容器并联连接，所述第二可变电容器和所述第四电容器并联连接。
结合第三方面及其上述实现方式，在第三方面的另一种实现方式中，所述方法还包括：在所述第三电容器和第四电容器的电容值被外界改变之前，调节所述第一可变电容器和所述第二可变电容器的电容，使得所述第一可变电容器的电容和所述第三电容器的电容之和等于所述第二可变电容器的电容和第四电容器的电容之和。
结合第三方面及其上述实现方式，在第三方面的另一种实现方式中，所述电容检测装置还包括第一可变电阻和第二可变电阻，所述第一可变电阻和所述第一电容器并联连接，所述第二可变电阻和所述第二电容器并联连接。
上述第三方面本发明实施例的电容检测方法可对应于第一方面本发明实施例的电容检测装置中的各个单元/模块，并且，该方法中的相应流程可以通过第一方面电容检测装置中的各个单元/模块来实现，为了简洁，在此不再赘述。
附图说明
图1是本发明一个实施例的电容检测装置的示意图。
图2是本发明一个实施例的电容检测装置的电路示意图。
图3是本发明另一实施例的电容检测装置的电路示意图。
图4是本发明再一实施例的电容检测装置的电路示意图。
图5是本发明再一实施例的电容检测装置的电路示意图。
图6是利用本发明一个实施例的电容检测装置构成的压力检测系统的示意图。
图7是利用本发明另一实施例的电容检测装置构成的压力检测系统的示意图。
图8是本发明一个实施例的电容检测方法的示意性流程图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述。
图1是本发明一个实施例的电容检测装置的示意图。图1所示的电容检测装置10包括控制模块11、充电模块12、计算模块13、差分放大器14、第一电容器15和第二电容器16。
具体地，可以通过控制模块控制充电模块对待测的两个电容器(如第三电容器和第四电容器)进行充电，并通过控制模块控制对第一电容器和第二电容器放电，使得第一电容器和第二电容器两端的电荷量都为零。接着，将充电后的第三电容器和第四电容器的电荷向第一电容器和第二电容器转移。然后，将第三电容器一端的电压和第四电容器一端的电压输入差分放大器，并在差分放大器的两个输出端口得到两个电压。将差分放大器的输出端的电压流向计算模块，以使得计算模块根据充电模块的供电电压、差分放大器的两个输出端的电压、第三电容器和第四电容器两端的电荷量向第一电容器和第二电容器转移的电荷转移系数、第一电容器的电容和所述第二电容器的电容，得到第三电容器的电容和第四电容器的电容的差。
本发明实施例可以通过对待测的两个电容器充电，然后将待测的电容器的电荷量向电容检测电路中的电容器转移，并通过差分放大器将待测电容器放电后的电压放大输出到计算模块，这样再通过差分放大器的输出端的电压计算可以实现不同电容器的电容差的检测。
在本发明的一个实施例中，电容检测装置还可以包括第一可变电容器和第二可变电容器。例如，将第一可变电容器和第三电容器并联连接，第二可变电容器和第四电容器并联连接，且第一可变电容器的电容和第三电容器的电容之和等于第二可变电容器的电容和第四电容器的电容之和。
在本发明的一个实施例中，电容检测装置还可以包括第一可变电阻和第 二可变电阻，第一可变电阻和第一电容器并联连接，第二可变电阻和第二电容器并联连接。
电容检测装置由于通电可能会导致温度发生改变，使得电容器的电容发生改变。本发明实施例可以检测两个电容器的电容差，通过将两个电容器配置在同一平面内，且两个电容器相互之间的距离较近，温度变化可以同时反馈在两个待检测的电容器上，并且温度变化对两个待检测的电容引起的变化或影响相当，这时进行差分处理，可以将温度变化引起的影响相互抵消，从而能够抑制温度漂移。
本发明实施例中的电容检测装置可以在电容触摸屏的电容主动笔压力不同时，根据检测到的电容变化模拟出压力大小，从而模拟真笔书写的体验，这样可以通过电容主动笔获得更加精准的输入，能够大幅提升用户体验。
本发明实施例中的电容检测装置对传统的按键或指纹识别，也可以通过检测电容的差从而感知手指的压力大小，从而能够提升用户体验。
另外，本发明实施例中的电容检测装置还可以通过检测电容的差得到手机屏幕上的压力大小，从而使手机屏幕变成一个高精度电子秤，这样可以提升手机压力应用场景，优化压力用户体验。
下面结合具体实施例详细说明本发明的电容检测装置。
图2是本发明一个实施例的电容检测装置的电路示意图。
第三电容器207和第四电容器208是待检测的电容器。本发明实施例中的第三电容器和第四电容器为自电容。
电容检测装置的电路包括：控制模块、第一电容器209、第二电容器210、充电模块211、差分放大器212和计算模块213。其中控制模块包括第一开关201、第二开关202、第三开关203、第四开关204、第五开关205和第六开关206。
在本发明的一个实施例中，充电模块211可以为电源。
第一开关201的一端与电源211连接，第一开关201的另一端与第三电容器207的一端连接，第三电容器207的另一端接地。第二开关202的一端与电源211连接，第二开关202的另一端与第四电容器208的一端连接，第四电容器208的另一端接地。
第三开关203的一端与第三电容器207的一端连接，第三开关203的另一端与第一电容器209连接。第四开关204的一端与第四电容器208的一端 连接，第四开关204的另一端与第二电容器210连接。
第五开关205与第一电容器209并联连接。第六开关206与第二电容器210并联连接。
差分放大器包括第一输入端、第二输入端、第一输出端和第二输出端。差分放大器212的第一输入端(如同向输入端)通过第三开关203与第三电容器207连接。差分放大器212的第二输入端(如反向输入端)通过第四开关204与第四电容器208连接。差分放大器的两个输出端口与计算模块213连接。差分放大器的第一输入端和待测的第三电容器相连接，第二输入端和待测的第四电容器相连接，第一输入端和第一输出端分别与第一电容器的两端连接，第二输入端和第二输出端分别与第二电容器的两端连接，第一输出端和第二输出端都与计算模块相连接。
本发明实施例可以通过对待测的两个电容器充电，然后将待测的电容器的电荷量向电容检测电路中的电容器转移，并通过差分放大器放大并将放大后的信号输出到计算模块，这样再通过差分放大器的输出端的电压计算可以实现不同电容器的电容差的检测。
第一阶段为充电复位阶段，对待测电容器进行充电，并对第一电容器209和第二电容器210都放电到电荷量为零。具体地，可以将第一开关201和第二开关202闭合，第三开关203和第四开关204断开，第五开关205和第六开关206闭合。这时电容检测装置中，电源211对第三电容器207和第四电容器208充电，且充电到V。第五开关205和第六开关206闭合，第一电容器209和第二电容器210两端通过导线连接，第一电容器209和第二电容器210两端的电压放电到共模电压，这时第一电容器两端的电压为零，第二电容器两端的电压也为零，第一电容器和第二电容器两端的电荷量也都为零。这时，差分放大器的两个输入端的电压都为共模电压，两个输出端的电压差为0，即Vout+-Vout-＝0。
第二阶段为放电检测阶段，将待测的第三电容器207和待测的第四电容器208充电后的电荷量向第一电容器209和第二电容器210转移。具体地，可以将第一开关和第二开关断开，将第三开关和第四开关闭合，第五开关和第六开关断开。这时电容检测装置中，电源211断开对第三电容器207和第四电容器208的充电。第三电容器207和第四电容器208分别向差分放大器212的两个输入端放电，第三电容器207两端的电荷量和第四电容器208两 端的电荷量分别转移到第一电容器209和第二电容器210上。
在本发明的一个实施例中，待测的第三电容器和待测的第四电容器的电容分别记为Cx1和Cx2，不同的待测电容器的电容值可能造成差分放大器的两个输出端的电压不同，以Vout+和Vout-分别表示差分放大器的两个输出端的电压，以Cfb1和Cfb2分别表示第一电容器和第二电容器的电容值，k为电荷转移系数，待测的第三电容器和待测的第四电容器的电容差:
△C＝Cx1-Cx2。其中，Cfb1＝Cfb2＝Cfb时，
对于Cx1，电荷转移系数k＝(Cfb-0.5*Cfb-0.5*Cx1/(Cfb+Cx1)。
对于Cx2，电荷转移系数k＝(Cfb-0.5*Cfb-0.5*Cx2)/(Cfb+Cx2)。
特别地，Cfb1＝Cfb2＝Cfb，待测的第三电容器和待测的第四电容器的电容差
Figure PCTCN2016104027-appb-000001
Cfb1和Cfb2设置为相同值时，可以使得电路操作简单，这样电容检测灵敏度可以更高。
本发明实施例对电容检测装置中第一电容器和第二电容器的电容值不做限制，可以利用较小的电容实现大电容的检测，例如，第一电容器和第二电容器的电容较小时，同样可以检测电容值较大的第三电容器和第四电容器的电容。这样，可以节省电容检测装置的电路中的芯片面积。
本发明实施例对充电模块的供电电压不做限制，本发明实施例可以用较低的电压对待测的电容器进行充电。
图3是本发明另一实施例的电容检测装置的电路示意图。图3中第三电容器307和第四电容器308是待检测的电容器。
电容检测装置的电路包括：控制模块、第一电容器309、第二电容器310、充电模块311、差分放大器312、计算模块313、第一可变电容器314、第二可变电容器315、第一可变电阻316和第二可变电阻317。其中控制模块包括第一开关301、第二开关302、第三开关303、第四开关304、第五开关305和第六开关306。本发明实施例图3中的器件和模块301-313和图2中的201-213对应的器件和模块的连接方式相同，功能相同，具体不再详细阐述。
在本发明的一个实施例中，可以是在图2电路的基础上增加两个可变电容，如图3中的第一可变电容器314和第二可变电容器315。其中，第一可变电容器314和第三电容器307并联连接，第二可变电容器315和第四电容器308并联连接，且第一可变电容器314的电容和第三电容器307的电容之和等于第二可变电容器315的电容和第四电容器308的电容之和。这样，在 没有压力时，待测电容器307和308的电容值不会改变。一般地，没有压力时待测电容器的电容值相等，但由于存在制造误差，没有压力时待测的两个电容器的电容值的差可能不为零，这个差可能使得差分放大器312的输出端有电压，占用电路的动态范围，影响电路的灵敏度。
本发明一个实施例中，通过增加可变电容器314和315，并在没有压力时调节可变电容器的电容，使得第一可变电容器314的电容和第三电容器307的电容之和等于第二可变电容器315的电容和第四电容器308的电容之和，这样在没有压力时，可以使得差分放大器312的输出端没有电压输出，可以提高有压力时的测量灵敏度。
在本发明的一个实施例中，可以是在图2电路的基础上增加两个可变电阻，例如图3中的第一可变电阻316和第二可变电阻317。其中，第一可变电阻316和第一电容器309并联连接，第二可变电阻317和第二电容器310并联连接。在本发明的一个实施例中，通过增加两个可变电阻，可以控制电路的频率响应，可以在有干扰的环境中起到抵抗干扰的作用，从而能够提高信噪比。
在本发明的一个实施例中，为了优化电路的工作状态，提高电路灵敏度，可以设置同一时刻第一可变电阻和第二可变电阻两个电阻值相同，假设都记为R，电路工作频率为f时可以设置R需要满足下列条件：
Figure PCTCN2016104027-appb-000002
图4是本发明再一实施例的电容检测装置的电路示意图。
图4中的第三电容器404和第四电容器405是待检测的电容器。第三电容器404和第四电容器405可以为互电容。
电容检测装置的电路包括：控制模块、第一电容器407、第二电容器408、充电模块401、差分放大器410和计算模块411。其中控制模块包括第七开关402、第八开关403、第九开关406和第十开关409。
在本发明的一个实施例中，充电模块401可以为电源。
第七开关402的一端与电源401连接，第八开关403的一端接地，另一端与两个待测电容器404和405的一端连接。两个待测电容器的两个另一端与差分放大器410的两个输入端分别连接，差分放大器410的两个输出端与计算模块411连接。第一电容器407的两端分别与差分放大器410的一个输入端(如图4中同向输入端)和一个输出端(如图4中的Vout-)连接，第二电容器408的两端分别与差分放大器410的另一个输入端(如图4中反向 输入端)和另一个输出端(如图4中的Vout+)连接。第九开关406与第一电容器407并联连接，第十开关409与第二电容器408并联连接。
本发明实施例可以通过对待测的两个电容器充电，然后将待测的电容器的电荷量向电容检测电路中的电容器转移，并通过差分放大器将待测电容器放电后的电压放大输出到计算模块，这样再通过差分放大器的输出端的电压计算可以实现不同电容器的电容差的检测。
具体地，第七开关402断开、第八开关403闭合、第九开关406闭合、第十开关409闭合时，电路处于复位状态，第一电容器407和第二电容器408两端的电压都放电到零，差分放大器410两个输出端的电压值相等，即输出端的电压差为零。
第一阶段为充电阶段，对待测电容器进行充电。具体地，第七开关402闭合、第八开关403断开、第九开关406断开、第十开关409断开，这时电源401对第三电容器404和第四电容器405充电，且都充电到电压V。
第二阶段为放电阶段，将待测的第三电容器404和待测的第四电容器405充电后的电荷量向第一电容器407和第二电容器408转移。具体地，可以将第七开关402断开、第八开关403闭合、第九开关406断开、第十开关409断开。
根据上述充电和放电阶段，在电路复位后，可以将开关407和开关408断开，开关402和开关403中的一个打开，一个关闭，交替执行，这样可以实现充电和放电的交替进行。
在本发明的一个实施例中，待测的第三电容器和待测的第四电容器的电容分别记为Cx1和Cx2，不同的待测电容器的电容值可能造成差分放大器的两个输出端的电压不同，以Vout+和Vout-分别表示差分放大器的两个输出端的电压，以Cfb1和Cfb2分别表示第一电容器和第二电容器的电容值，k为电荷转移系数，待测的第三电容器和待测的第四电容器的电容差：
△C＝Cx1-Cx2。其中，Cfb1＝Cfb2＝Cfb时，
对于Cx1，电荷转移系数k＝(Cfb-0.5*Cfb-0.5*Cx1/(Cfb+Cx1)。
对于Cx2，电荷转移系数k＝(Cfb-0.5*Cfb-0.5*Cx2)/(Cfb+Cx2)。
特别地，Cfb1＝Cfb2＝Cfb，那么待测的第三电容器和待测的第四电容器的电容差为：
Figure PCTCN2016104027-appb-000003
Cfb1和Cfb2设置为相同值时，可以使得电路操作简单，这样电容检测灵敏度可以更高。
图5是本发明再一实施例的电容检测装置的电路示意图。
图5中的第三电容器504和第四电容器505是待检测的电容器。
电容检测装置的电路包括：控制模块、第一电容器507、第二电容器508、充电模块501、差分放大器510、计算模块511、第一可变电容器512、第二可变电容器513、第一可变电阻514和第二可变电阻515。其中控制模块包括第七开关502、第八开关503、第九开关506和第十开关509。本发明实施例图5中的器件和模块501-511和图4中的401-411对应的器件和模块的连接方式相同，功能相同，具体不再详细阐述。
在本发明的一个实施例中，可以是在图4电路的基础上增加两个可变电容，如图5中的第一可变电容器512和第二可变电容器513。其中，第一可变电容器512和第三电容器504并联连接，第二可变电容器513和第四电容器505并联连接，且第一可变电容器512的电容和第三电容器504的电容之和等于第二可变电容器513的电容和第四电容器505的电容之和。这样，在没有压力时，待测电容器的电容值不会改变。一般地，没有压力时待测电容器的电容值相等，但由于存在制造误差，没有压力时待测的两个电容器的电容值的差值可能不为零，这个差值可能使得差分放大器的输出端有电压，占用电路的动态范围，影响电路的灵敏度。
在本发明的一个实施例中，本发明实施例中的电容检测装置可以应用在手机中，用来根据电容差值检测施加在手机显示屏的压力，以及用在主动笔上用来根据电容差值检测压力时，在压力按压前，才涉及调节可变电容器进而提高压力检测的灵敏度。例如，在电容检测装置中可以通过增加可变电容器，并在没有压力时调节可变电容器的电容，使得第一可变电容器的电容和第三电容器的电容之和等于第二可变电容器的电容和第四电容器的电容之和，这样在没有压力时，可以使得差分放大器的输出端没有电压输出，可以提高有压力时的测量灵敏度。
在本发明的一个实施例中，可以是在图4电路的基础上增加两个可变电阻，例如图5中的第一可变电阻514和第二可变电阻515。其中，第一可变电阻和第一电容器并联连接，第二可变电阻和第二电容器并联连接。在本发明的一个实施例中，通过增加两个可变电阻，可以控制电路的频率响应，可以在有干扰的环境中起到抵抗干扰的作用，从而能够提高信噪比。
在本发明的一个实施例中，为了优化电路的工作状态，提升电路的灵敏 度，可以设置第一可变电阻和第二可变电阻两个电阻值相同，假设都记为R，电路工作频率为f时可以设置R需要满足下列条件：
Figure PCTCN2016104027-appb-000004
上述结合图1至图5详细说明电容检测装置的电路示意图，下面结合图6和图7说明上述电容检测装置的应用实例。这里，图6和图7以手机压力检测实例为例进行说明。
图6是利用本发明一个实施例的电容检测装置构成的压力检测系统的示意图。
压力检测系统包括至少一个电容检测装置200、手机显示屏601、待检测电容器的检测电极和压力检测模块602。其中，待检测电容器包括C1、C2、C3、C4、C5、C6、C7、C8。本发明一个实施例中的待检测电容器可以为自电容，待检测电容器一端接地，另一端为检测电极，检测电极可以位于显示屏和中框之间，且检测电极和中框之间具有间隙。例如，可将检测电极贴在显示屏的背后。每个电容检测装置200连接两个待检测的检测电极，检测两个电容器之间的电容差。
手指按压手机显示屏，引起形变，使得检测电极对地电容发生变化，即待检测电容器的电容发生变化，利用电容检测装置所示的电路图可以得到两个待检测电容器的电容差，实现压力检测。在本发明的一个实施例中，可以将C1、C2、C3、C4设置在中间，C5、C6、C7、C8设置在边角上。中间电容器受压力时的对地电容变化明显，边角上的电容器受压力时对地电容变化较小，中间电容器和边角上的电容器的电容求差，可以得到两个电容器的电容差。这样，通过计算处于同一环境中的电容器的电容差，可以减小由于外界环境变化引起的电容的变化。例如，外界环境温度或湿度不同时，同一个电容器同一种状态下的电容值可能会有所不同。通过本发明的一个实施例求两个电容的差可以防止温度或湿度等的改变引起的电容值的漂移。
在本发明的一个实施例中，可以将检测电极贴在显示屏的背后，并且检测电极与中框有一定的间隙，间隙可以填充空气，也可以填充弹性材料。
在本发明的一个实施例中，电容检测装置200可以为一个，也可以为多个，本发明实施例对此不做限制。图6中是以四个电容检测装置为例进行说明。
在本发明的一个实施例中，电容检测装置200可以如图2中的200所示的电路图，还可以在200的基础上增加可变电容器和/或可变电阻，如图3 中的300所示的电路图。图6中画出的是电容检测装置为图2所示的检测装置的实例。
本发明实施例中的压力检测模块602可以根据电容检测装置得到的电容差得到待检测的压力。
图7是利用本发明另一实施例的电容检测装置构成的压力检测系统的示意图。
压力检测系统包括至少一个电容检测装置400、手机显示屏701、中框702、待检测电容器两个电极703和压力检测模块704。其中，待检测电容器包括C1、C2、C3、C4、C5、C6、C7、C8。每个待检测的电容器包括两个电极，且两个电极都位于手机显示屏和中框之间。每个电容检测装置400用于检测两个电容器之间的电容差。
手指按压手机显示屏，引起形变，使得待检测电容器的电容发生变化，利用电容检测装置所示的电路图可以得到电容差，实现压力检测。在本发明的一个实施例中，可以将C1、C2、C3、C4设置在中间，C5、C6、C7、C8设置在边角上。中间电容器受压力时的电容变化明显，边角上的电容器受压力时电容变化较小，中间电容器和边角上的电容器的电容求差，可以得到两个电容器的电容差。这样，通过计算处于同一环境中的电容器的电容差，可以减小由于外界环境变化引起的电容的变化。例如，外界环境温度或湿度不同时，同一个电容器同一种状态下的电容可能会有所不同。通过本发明实施例求两个电容器的差可以防止温度或湿度等的改变引起的电容值的漂移。
在本发明的一个实施例中，可以将待检测电容器的两个电极一个贴在显示屏的背后，一个贴在中框上，使得两个电极之间构成一定的间隙。这里，间隙可以填充空气，也可以填充弹性材料。
在本发明的一个实施例中，电容检测装置400可以如图4中的400所示的电路图，还可以在400的基础上增加可变电容器和/或可变电阻，如图5中的500所示的电路图。图7中画出的是电容检测装置为图4所示的检测装置的实例。
本发明实施例中的压力检测模块704可以根据电容检测装置得到的电容差得到待检测的压力。
图8是本发明一个实施例的电容检测方法的示意性流程图。本发明实施例的电容检测方法可以由电容检测装置执行。电容检测装置可以包括差分放 大器、第一电容器、第二电容器、充电模块、控制模块和计算模块。其中，差分放大器包括第一输入端、第二输入端、第一输出端和第二输出端。第一输入端和待测的第三电容器相连接，第二输入端和待测的第四电容器相连接。电容检测方法的具体流程如下。
801，在第一阶段，通过控制模块控制充电模块对待测的第三电容器和待测的第四电容器进行充电，并控制对第一电容器和第二电容器进行放电。
802，在第二阶段，通过控制模块控制充电模块断开对第三电容器和第四电容器的充电，控制第三电容器向所述第一电容器放电，并控制第四电容器向第二电容器放电。
803，通过差分放大器放大，并将放大后的信号分别从第一输出端和第二输出端输出到计算模块。
804，通过计算模块根据充电模块的供电电压、第一输出端的电压、第二输出端的电压、第一电容器的电容和第二电容器的电容得到第三电容器的电容和第四电容器的电容的差。
本发明实施例可以通过对待测的两个电容器充电，然后将待测的电容器的电荷量向电容检测电路中的电容器转移，并通过差分放大器放大将放大后的信号输出到计算模块，这样再通过差分放大器的输出端的电压计算可以实现不同电容器的电容差的检测。
根据本发明实施例的电容检测方法可对应于本发明实施例的电容检测装置中的各个单元/模块，并且，该方法中的相应流程都可以通过图1至图7中所示装置中的各个单元/模块来实现，为了简洁，在此不再赘述。
应理解，说明书通篇中提到的“一个实施例”或“一实施例”意味着与实施例有关的特定特征、结构或特性包括在本发明的至少一个实施例中。因此，在整个说明书各处出现的“在一个实施例中”或“在一实施例中”未必一定指相同的实施例。此外，这些特定的特征、结构或特性可以任意适合的方式结合在一个或多个实施例中。
应理解，在本发明的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本发明实施例的实施过程构成任何限定。
应理解，在本发明实施例中，“与A相应的B”表示B与A相关联，根据A可以确定B。但还应理解，根据A确定B并不意味着仅仅根据A确定 B，还可以根据A和/或其它信息确定B。
另外，本文中术语“系统”和“网络”在本文中常可互换使用。应理解，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本发明的范围。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本发明各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
本领域普通技术人员可以理解，实现上述方法实施方式中的全部或部分步骤是可以通过程序来指令相关的硬件来完成，所述的程序可以存储于计算机可读取存储介质中。这里所称得的存储介质，可以包括：U盘、移动硬盘、只读存储器(ROM，Read-Only Memory)、随机存取存储器(RAM，Random Access Memory)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限 于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

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  1. 一种电容检测装置，其特征在于，所述装置包括差分放大器、第一电容器、第二电容器、充电模块、控制模块和计算模块，所述差分放大器包括第一输入端、第二输入端、第一输出端和第二输出端；
    所述第一输入端和待测的第三电容器相连接，所述第二输入端和待测的第四电容器相连接，所述第一输入端和所述第一输出端分别与所述第一电容器的两端连接，所述第二输入端和所述第二输出端分别与所述第二电容器的两端连接，所述第一输出端和所述第二输出端都与所述计算模块相连接；
    在第一阶段，所述控制模块用于控制所述充电模块对所述第三电容器和所述第四电容器进行充电，所述控制模块还用于控制所述第一电容器和所述第二电容器进行放电；
    在第二阶段，所述控制模块用于控制所述充电模块断开对所述第三电容器和所述第四电容器的充电，所述控制模块还用于控制所述第三电容器向所述第一电容器放电，并控制所述第四电容器向所述第二电容器放电；
    所述差分放大器用于放大并将放大后的信号从所述第一输出端和所述第二输出端输出到所述计算模块；
    所述计算模块用于根据所述充电模块的供电电压、所述第一输出端的电压、所述第二输出端的电压、所述第一电容器的电容和所述第二电容器的电容得到所述第三电容器的电容和所述第四电容器的电容的差。
  2. 如权利要求1所述的装置，其特征在于，所述装置还包括第一可变电容器和第二可变电容器，所述第一可变电容器和所述第三电容器并联连接，所述第二可变电容器和所述第四电容器并联连接。
  3. 如权利要求2所述的装置，其特征在于，所述电容检测装置还包括第一可变电阻和第二可变电阻，所述第一可变电阻和所述第一电容器并联连接，所述第二可变电阻和所述第二电容器并联连接。
  4. 如权利要求3所述的装置，其特征在于，在所述第三电容器和第四电容器的电容值被外界改变之前,所述第一可变电容器的电容和所述第三电容器的电容之和等于所述第二可变电容器的电容和所述第四电容器的电容之和。
  5. 如权利要求3或4所述的装置，其特征在于，同一时间，所述第一 可变电阻的电阻值和所述第二可变电阻的电阻值相同。
  6. 如权利要求1-5中任一项所述的装置，其特征在于，所述第一电容器的电容和所述第二电容器的电容相同。
  7. 如权利要求1-6中任一项所述的装置，其特征在于，所述充电模块为电源；
    所述控制模块包括第一开关和第二开关；
    第一开关的一端与所述电源连接，所述第一开关的另一端与所述第三电容器的一端连接，所述第三电容器的另一端接地，所述第一开关闭合时使得所述电源对所述第三电容器充电，所述第一开关断开时使得断开所述电源对所述第三电容器的充电；
    所述第二开关的一端与所述电源连接，所述第二开关的另一端与所述第四电容器的一端连接，所述第四电容器的另一端接地，所述第二开关闭合时使得所述电源对所述第四电容器充电，所述第二开关断开时使得断开所述电源对所述第四电容器的充电。
  8. 如权利要求1-7中任一项所述的装置，其特征在于，所述控制模块包括第三开关，第四开关、第五开关和第六开关；
    所述第三开关的一端与所述第三电容器的一端连接，所述第三开关的另一端与所述第一电容器连接，所述第五开关与所述第一电容器并联连接；
    所述第四开关的一端与所述第四电容器的一端连接，所述第四开关的另一端与所述第二电容器连接，所述第六开关与所述第二电容器并联连接；
    在所述第一阶段，所述第三开关断开且所述第五开关闭合时，使得所述第一电容器放电至所述第一电容器两端电荷量为零；
    在所述第一阶段，所述第四开关断开且所述第六开关闭合时，使得所述第二电容器放电至所述第二电容器两端电荷量为零；
    在所述第二阶段，所述充电模块断开充电，所述第三开关闭合且所述第五开关断开时，使得所述第三电容器向所述第一电容器放电；
    在所述第二阶段，所述充电模块断开充电，所述第四开关闭合且所述第六开关断开时，使得所述第四电容器向所述第二电容器放电。
  9. 如权利要求1-6中任一项所述的装置，其特征在于，所述充电模块为电源；
    所述控制模块包括第七开关、第八开关、第九开关和第十开关；
    所述第七开关的第一端与所述电源连接，所述第七开关的第二端与所述第三电容器的第一端连接，所述第七开关的第二端与所述第四电容器的第一端也连接，所述第八开关的第一端接地，所述第八开关的第二端与所述第三电容器的第一端连接，所述第八开关的第二端与所述第四电容器的第一端也连接，所述差分放大器的第一输入端与所述第三电容器的第二端连接，所述差分放大器的第二输入端与所述第四电容器的第二端连接；
    所述第九开关与所述第一电容器并联连接，所述第十开关与所述第二电容器并联连接。
  10. 如权利要求9所述的装置，其特征在于，在所述第一阶段，所述第七开关、所述第九开关和所述第十开关都闭合，且所述第八开关断开时，使得所述电源对所述第三电容器和所述第四电容器充电，所述第一电容器和所述第二电容器都放电到两端电荷量为零；
    在所述第二阶段，所述第七开关、所述第九开关和所述第十开关都断开，且所述第八开关闭合时，使得所述第三电容器向所述第一电容器放电，且所述第四电容器向所述第二电容器放电。
  11. 一种压力检测系统，其特征在于，所述压力检测系统包括压力检测模块、至少一个如权利要求1-10中任一项所述的电容检测装置、至少一个所述第三电容器和至少一个所述第四电容器，其中，每个电容检测装置对应一个待测的第三电容器和一个待测的第四电容器，所述压力检测模块用于根据所述至少一个所述第三电容器的电容和所述至少一个所述第四电容器的电容的差得到被检测的压力。
  12. 如权利要求11所述的系统，其特征在于，所述压力检测系统还包括显示屏和中框，所述第三电容器及第四电容器为自电容，所述至少一个所述第三电容器的检测电极和所述至少一个所述第四电容器的检测电极位于显示屏和中框之间，所述第三电容器的检测电极和所述中框之间具有间隙，所述第四电容器的检测电极和所述中框之间具有间隙。
  13. 一种电容检测方法，其特征在于，所述方法由电容检测装置执行，所述电容检测装置包括差分放大器、第一电容器、第二电容器、充电模块、控制模块和计算模块，所述差分放大器包括第一输入端、第二输入端、第一输出端和第二输出端，所述第一输入端和待测的第三电容器相连接，所述第二输入端和待测的第四电容器相连接，所述方法包括：
    在第一阶段，通过所述控制模块控制所述充电模块对所述第三电容器和所述第四电容器进行充电，并控制对所述第一电容器和所述第二电容器进行放电；
    在第二阶段，通过所述控制模块控制所述充电模块断开对所述第三电容器和所述第四电容器的充电，控制所述第三电容器向所述第一电容器放电，并控制所述第四电容器向所述第二电容器放电；
    通过所述差分放大器放大并将放大后的信号从所述第一输出端和所述第二输出端输出到所述计算模块；
    通过所述计算模块根据所述充电模块的供电电压、所述第一输出端的电压、所述第二输出端的电压、所述第一电容器的电容和所述第二电容器的电容得到所述第三电容器的电容和所述第四电容器的电容的差。
  14. 如权利要求13所述的方法，其特征在于，所述电容检测装置还包括第一可变电容器和第二可变电容器，所述第一可变电容器和所述第三电容器并联连接，所述第二可变电容器和所述第四电容器并联连接。
  15. 如权利要求13或14所述的方法，其特征在于，所述方法还包括：
    在所述第三电容器和第四电容器的电容值被外界改变之前，调节所述第一可变电容器和所述第二可变电容器的电容，使得所述第一可变电容器的电容和所述第三电容器的电容之和等于所述第二可变电容器的电容和第四电容器的电容之和。
  16. 如权利要求13-15中任一项所述的方法，其特征在于，所述电容检测装置还包括第一可变电阻和第二可变电阻，所述第一可变电阻和所述第一电容器并联连接，所述第二可变电阻和所述第二电容器并联连接。
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