WO2022052064A1 - 电容检测电路、触控芯片和电子设备 - Google Patents

电容检测电路、触控芯片和电子设备 Download PDF

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Publication number
WO2022052064A1
WO2022052064A1 PCT/CN2020/114890 CN2020114890W WO2022052064A1 WO 2022052064 A1 WO2022052064 A1 WO 2022052064A1 CN 2020114890 W CN2020114890 W CN 2020114890W WO 2022052064 A1 WO2022052064 A1 WO 2022052064A1
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circuit
sub
noise
capacitance
signal
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PCT/CN2020/114890
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English (en)
French (fr)
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袁广凯
蒋宏
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深圳市汇顶科技股份有限公司
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Priority to PCT/CN2020/114890 priority Critical patent/WO2022052064A1/zh
Priority to US17/477,220 priority patent/US11435855B2/en
Publication of WO2022052064A1 publication Critical patent/WO2022052064A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/45—Differential amplifiers
    • H03F3/45071—Differential amplifiers with semiconductor devices only
    • H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
    • H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
    • 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
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
    • G06F3/04184—Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
    • 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
    • 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
    • G06F3/0446—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
    • H03F2203/45—Indexing scheme relating to differential amplifiers
    • H03F2203/45522—Indexing scheme relating to differential amplifiers the FBC comprising one or more potentiometers

Definitions

  • the embodiments of the present application relate to the field of capacitance detection, and more particularly, to a capacitance detection circuit, a touch control chip, and an electronic device.
  • Capacitive sensors are widely used in electronic products for touch detection.
  • a conductor such as a finger touches or approaches the detection electrode in the touch screen of the electronic device
  • the capacitance corresponding to the detection electrode will change. user's actions.
  • the noise generated by the display screen of the electronic device will affect the above detection results. Therefore, how to reduce the influence of display screen noise on capacitance detection has become an urgent problem to be solved.
  • Embodiments of the present application provide a capacitance detection circuit, a touch control chip, and an electronic device, which can reduce the influence of display screen noise on capacitance detection.
  • a capacitance detection circuit including:
  • an amplifying circuit connected to the detection capacitance in the touch screen, for amplifying the capacitance signal of the detection capacitance and converting it into a voltage signal, and the voltage signal is used to determine the detection capacitance;
  • a control circuit connected to the amplifying circuit, is used to control the magnification of the amplifying circuit, wherein a period in which a noise peak of the noise signal of the display screen is located includes consecutive N sub-periods, and the amplifying circuit is in the N sub-periods.
  • the magnification in the sub-periods is inversely proportional to the size of the noise signal in the N sub-periods, N>1.
  • the amplifying circuit includes an operational amplifier, an adjustable resistor is connected between the input end and the output end of the operational amplifier, and the control circuit is specifically configured to: control the adjustable resistance resistance value, so that the amplification factor of the amplifying circuit in the N sub-periods is inversely proportional to the size of the noise signal in the N sub-periods.
  • the operational amplifier is a differential operational amplifier
  • the adjustable resistor is connected between the first input end and the first output end of the differential operational amplifier
  • the differential operational amplifier The adjustable resistor is connected between the second input terminal and the second output terminal.
  • the amplification factor of the amplifying circuit is a constant value in the period in which the non-noise peak value of the noise signal is located.
  • the constant value is greater than or equal to the maximum amplification factor of the amplification circuit within the N sub-periods.
  • the time period in which the noise peak of the noise signal is located is determined according to the scanning frequency of the horizontal synchronization signal of the display screen.
  • one scan period of the line synchronization signal of the display screen includes one or two of the noise peaks.
  • the capacitance detection circuit further includes: a filtering circuit, connected to the amplifying circuit, and configured to perform filtering processing on the voltage signal output by the amplifying circuit.
  • the capacitance detection circuit further includes: an ADC circuit, connected to the filter circuit, for converting the filtered voltage signal into a digital signal.
  • a touch control chip including: the first aspect and the capacitance detection circuit in any possible implementation manner of the first aspect.
  • an electronic device including: a touch screen; a display screen; and a touch control chip in the foregoing second aspect and any possible implementation manner of the second aspect.
  • the period where the noise peak of the noise signal of the display screen is located is divided into consecutive N sub-periods, and the amplification factor of the amplifying circuit in the N sub-periods is controlled by the control circuit, so that the amplifying circuit is in the N sub-periods.
  • the amplification factor within N sub-periods is inversely proportional to the size of the noise signal in N sub-periods to avoid saturation of the amplification circuit.
  • the capacitance detection circuit improves the signal-to-noise ratio of capacitance detection while ensuring the effective operation of the amplifying circuit, and has better detection performance.
  • FIG. 1 is a schematic diagram of the principle of capacitance detection.
  • FIG. 2 is a schematic structural diagram of a possible capacitance detection system according to an embodiment of the present application.
  • FIG. 3 is a schematic block diagram of a capacitance detection circuit according to an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the relationship between noise magnitude and magnification.
  • FIG. 5 is a schematic diagram of the relationship between noise magnitude and magnification.
  • FIG. 6 is a schematic diagram of an amplifying circuit according to an embodiment of the present application.
  • FIG. 7 is a possible specific implementation based on the capacitance detection circuit shown in FIG. 3 .
  • FIG. 8 is a possible specific implementation based on the capacitance detection circuit shown in FIG. 3 .
  • FIG. 1 is a schematic diagram of the principle of touch detection.
  • Figure 1 shows the horizontal and vertical two-layer channels in the touch panel.
  • a capacitive touch system using this pattern can usually use both self-capacitance and mutual-capacitance detection methods at the same time.
  • the touch chip When performing self-capacitance detection, the touch chip will scan the change of the self-capacitance to ground of each horizontal channel and vertical channel. When a finger approaches or touches, the self-capacitance of the channel near the finger becomes larger.
  • TX channel drive channel
  • RX channel sensing channel
  • the touch chip detects the change in mutual capacitance between TX and RX.
  • the finger and its nearby lateral channel C RXN-1 will generate capacitance Cs
  • the finger and its nearby vertical channel C TX1 will generate capacitance Cd. Since the human body is a conductor and is connected to the ground, the self-capacitance and mutual capacitance of the channel touched or approached by the finger will change.
  • the touch chip can calculate the touch position of the finger according to the detected change of the self-capacitance or mutual capacitance.
  • FIG. 2 is a schematic structural diagram of a possible capacitance detection system involved in the present application.
  • the touch panel 210 is connected to a touch chip (touch IC) 220 , wherein the touch IC 220 includes a synchronous control circuit 221 , a drive circuit 222 , and a capacitance detection circuit 223 .
  • the synchronization control circuit 221 is used to receive the horizontal synchronization signal (referred to as Hsync signal) and the vertical synchronization signal (referred to as Vsync signal) of the display, and generate related trigger signals inside the capacitance detection system.
  • Hsync signal horizontal synchronization signal
  • Vsync signal vertical synchronization signal
  • the driving circuit 222 is used for generating a driving signal, or called a coding signal, and the coding signal can be input to the TX channel in the touch panel.
  • the capacitance detection circuit 223 may include, for example, a programmable gain amplifier (Programmable Gain Amplifier, PGA), an analog antialiasing filter (Analog Antialiasing Filter, AAF) with low-pass characteristics, an analog-to-digital conversion circuit (Analog to Digital Conversion Circuit, ADC) )Wait.
  • the PGA circuit can be used to receive the signal transmitted by the RX channel in the touch panel and amplify it; the AAF circuit is connected to the PGA circuit to filter out the interference signal carried in the received electrical signal ; The ADC circuit is connected to the AAF circuit for converting the analog signal into a digital signal.
  • the main panel parameters have changed greatly. , which significantly increases the display noise caused by the Display Driver Integrated Circuit (DDIC) in the screen.
  • DDIC Display Driver Integrated Circuit
  • the noise of the display screen will affect the capacitance detection circuit in the touch screen, so that the detection sensitivity of the capacitance detection circuit to self-capacitance and mutual capacitance is significantly reduced.
  • the present application provides a capacitance detection circuit, which can reduce the influence of display screen noise on capacitance detection of a touch screen.
  • FIG. 3 is a schematic block diagram of a capacitance detection circuit according to an embodiment of the present application. As shown in FIG. 3 , the capacitance detection circuit 300 includes an amplification circuit 310 and a control circuit 320 .
  • the amplifying circuit 310 is connected to the detection capacitor C X in the touch screen (also referred to as the touch screen), and is used for amplifying the capacitance signal of the detection capacitor C X and converting it into a voltage signal. Wherein, the voltage signal is used to determine the detection capacitance C X .
  • the control circuit 320 is connected to the amplifying circuit 310 for controlling the magnification of the amplifying circuit 310 .
  • the period in which a noise peak of the noise signal of the display screen is located includes consecutive N sub-periods, and the amplification factor of the amplifying circuit 310 in the N sub-periods is inversely proportional to the size of the noise signal in the N sub-periods, N>1 .
  • the display screen and the touch screen described in the embodiments of the present application may be regarded as the display layer and the touch screen in the screen of the electronic device, respectively.
  • the screen of the circuit device usually includes a display layer and a touch layer, which are respectively used to realize the display function and the touch function.
  • the scanning signal such as the line synchronization signal of the display screen
  • the line synchronization signal changes according to certain rules, such as periodic changes, and the phase difference between the noise signal of the display screen and the line synchronization signal of the display screen is basically unchanged, so the noise signal generated by the display screen will also follow Certain rules change.
  • the noise signal generated by the display screen is divided in time.
  • the period where the noise peak of the noise signal is located is divided into N sub-periods, namely T1, T2, . . . , Ti, . . . T N .
  • the control circuit can control the amplification factor of the amplifying circuit 310 in the N sub-periods according to the size of the noise signal in the N sub-periods. Wherein, in the sub-period when the noise signal is larger, the amplification factor of the amplifying circuit is smaller; in the sub-period when the noise signal is smaller, the amplification factor of the amplifying circuit is larger.
  • the amplification factor of the amplifying circuit 310 can be increased according to the corresponding amplification factor preset for different sub-periods. make adjustments.
  • the time period in which the noise peak value is located in the embodiments of the present application refers to the starting moment when the noise of the display screen changes from a low level to a high level to the end moment when the noise changes from a high level to a low level period in between.
  • Figure 4 shows three noise peaks, wherein each noise peak includes the time period from T1 to T6; for another example, Figure 5 shows three noise peaks, wherein the first noise peak and the third noise peak The peaks all include the period from T1 to T6, and the second noise peak includes the period from T8 to T12.
  • the period in which the noise peak of the noise signal generated by the display screen is located is divided into sub-periods T1 , T2 , T3 , T4 , T5 and T6 .
  • the noise signal generated by the display screen in the sub-period T3 is the largest, and the noise signal generated in the sub-periods T1 and T6 is the smallest.
  • the control circuit 320 controls the amplifying circuit 310 in the sub-periods T1, T2, T3, T4 according to the size of the noise signal generated by the display screen in the sub-periods T1, T2, T3, T4, T5 and T6, that is, the voltage amplitude of the noise signal.
  • Figure 4 shows the situation where there is one noise peak in one line sync scan period.
  • there may also be two or more noise peaks in the scan period of one line sync signal and the time period where each noise peak is located
  • the variation of the noise signal in the signal can be the same or different. Therefore, according to the characteristics of each noise peak, the time period in which each noise peak is located can be divided into the same or different number N of sub-periods. For example, in the scanning period of a line synchronization signal, the period in which the first noise peak is located includes N1 sub-periods, and the period in which the second noise peak is located includes N2 sub-periods.
  • control circuit 320 controls the amplification factor of the amplifying circuit 310 in the sub-periods T1, T2, T3, T4, T5 and T6 to be inversely proportional to the magnitude of the noise signal; and the control circuit 320 controls the amplifying circuit 310 in the sub-periods T8, T9 , T10, T11 and T12 the amplification factor is inversely proportional to the size of the noise signal. As shown in FIG.
  • the period where the noise peak of the noise signal of the display screen is located is divided into consecutive N sub-periods, and the amplification factor of the amplifying circuit 310 in the N sub-periods is controlled by the control circuit 320, so that the amplifying circuit 310 is in the N sub-periods.
  • the amplification factor within N sub-periods is inversely proportional to the size of the noise signal in N sub-periods to avoid saturation of the amplification circuit 310 .
  • the capacitance detection circuit 300 improves the signal-to-noise ratio of capacitance detection while ensuring the effective operation of the amplifying circuit 310, and has better detection performance.
  • N 1
  • the capacitance detection circuit 300 has a stronger adaptability to noise changes, and can be applied to a situation where there are multiple noise peaks in a scanning period of a horizontal synchronization signal.
  • This embodiment of the present application does not limit how to determine the size of the noise signal in each of the N sub-periods. For example, it can be determined according to the magnitude of the noise signal at a certain moment in the sub-period; for another example, it can be determined according to the average value of the noise signals at multiple moments in the sub-period. This application does not limit this.
  • the size of the noise signal in the N sub-periods may be an ideal reciprocal relationship between the size of the noise signal in the N sub-periods and the amplification factor of the amplifying circuit 310 in the N sub-periods.
  • the size of the noise signal in the sub-period T1 and the sub-period T2 can be equal to the ratio between the amplification factor A2 of the amplifying circuit 310 in the sub-period T2 and the amplification factor A1 of the amplifying circuit 310 in the sub-period T1, but the present application is not limited to this, the noise signal in the sub-period T1 When the size of the noise signal is smaller than the sub-period T2, it is only necessary to make A1>A2.
  • the amplification factor of the amplifying circuit 310 in the period in which the non-noise peak of the noise signal of the display screen is located may be, for example, a constant value.
  • the constant value may be, for example, greater than or equal to the maximum amplification factor of the amplification circuit 310 in N sub-periods. For example, in the period T7 where the non-noise peak in FIG. 4 or FIG.
  • the magnification of the amplifying circuit 310 may be equal to the maximum magnification of the amplifying circuit 310 in N sub-periods, that is, the magnifications corresponding to the sub-periods T1 and T6 It can also be greater than the amplification factor of the amplifying circuit 310 in N sub-periods, that is, greater than the amplification factors corresponding to the sub-periods T1 and T6. For another example, in the period T13 where the non-noise peak is located in FIG.
  • the amplification factor of the amplifying circuit 310 may be equal to the maximum amplification factor of the amplifying circuit 310 in the N2 sub-periods, that is, the amplification factors corresponding to the sub-periods T8 and T12 are equal; It can be larger than the amplification factor of the amplifying circuit 310 in N2 sub-periods, that is, larger than the amplification factors corresponding to the sub-periods T8 and T12.
  • the time period in which the noise peak of the noise signal is located is determined according to the scanning frequency of the horizontal synchronization signal of the display screen. For example, the phase relationship between the noise peak value of the noise signal of the display screen and the horizontal synchronization signal can be obtained by detecting the output signal of the capacitance detection circuit 300, and further, the size of the noise peak value can be obtained.
  • the amplification factors corresponding to the N sub-periods of the amplifying circuit 310 in the period where the noise peak is located are determined.
  • the input terminal of the amplifying circuit 310 is connected to the detection capacitor Cx, and outputs a voltage signal associated with the detection capacitor Cx. After the amplification factor of the amplifying circuit 310 is adjusted, the amplified voltage signal can be output based on the amplification factor. When the capacitance of the detection capacitor Cx changes, the voltage signal output by the amplifying circuit 310 will also change. That is to say, the amplifying circuit 310 can convert the capacitance signal of the detection capacitance Cx into a voltage signal and amplify it, so as to realize the detection of the detection capacitance Cx.
  • the control circuit 320 is connected to the amplifying circuit 310 for controlling the magnification of the amplifying circuit 310 .
  • the amplifying circuit 310 has a relatively large magnification in the sub-period with low display screen noise, so as to improve the SNR of capacitive detection; while the amplifying circuit 310 has a relatively small magnification in the sub-period with large display screen noise, In order to avoid saturation of the amplifying circuit 310, the effective operation of the amplifying circuit 310 is ensured. Therefore, the capacitance detection circuit 300 improves the signal-to-noise ratio of capacitance detection while ensuring the effective operation of the amplifying circuit 310, and has better detection performance.
  • the capacitance detection circuit in this embodiment of the present application may be used for mutual capacitance detection or self-capacitance detection, and the detection capacitance Cx may be the self-capacitance of the TX channel or the RX channel to the ground, or the detection capacitance Cx may be the self-capacitance between the TX channel and the RX channel.
  • mutual capacitance The TX channel is used for input drive signal.
  • the RX channel is used to sense the drive signal and generate the detection signal. The following description only takes mutual capacitance detection as an example.
  • the amplifying circuit 310 includes an operational amplifier, for example, the amplifying circuit 310 may be a programmable gain amplifier (Programmable Gain Amplifier, PGA). Among them, an adjustable resistor connected between the input end and the output end of the operational amplifier is also called a variable resistor.
  • the control circuit 320 is specifically used to control the resistance of the adjustable resistor, so that the amplification factor of the amplifier circuit 310 in the N sub-periods is inversely proportional to the size of the noise signal in the N sub-periods.
  • the operational amplifier can be a differential operational amplifier, and the differential operational amplifier can convert the capacitance signal of the detection capacitor Cx into a voltage signal V OUT , and the voltage signal V OUT is a differential signal with better signal-to-noise Compare.
  • An adjustable resistor R f1 is connected between the first input end and the first output end of the differential operational amplifier, and an adjustable resistor R f2 is connected between the second input end and the second output end of the differential operational amplifier .
  • R f1 and R f2 are equal.
  • R f1 and R f2 may have multiple gears, and the multiple gears correspond to multiple resistance values, and the multiple resistance values are respectively used to match the noise signals in the N sub-periods.
  • R f1 and R f2 will be adjusted to smaller resistance values, so that the amplifier circuit 310 has a relatively small amplification factor; and in the sub-period when the noise signal is relatively small, R f1 and R f2 will be adjusted to larger resistance values, so that the amplifier circuit 310 has a larger amplification factor.
  • a feedback capacitor C f1 and a feedback capacitor C f2 which are respectively connected in parallel with the feedback resistor R f1 and the feedback resistor R f2 may be further provided.
  • the capacitance detection circuit 300 further includes: a filtering circuit 340 , which is connected to the amplifying circuit 310 and is used for filtering the voltage signal output by the amplifying circuit 310 .
  • the capacitance detection circuit 300 further includes: an ADC circuit 350 connected to the filter circuit 340 for converting the filtered voltage signal into a digital signal.
  • FIG. 7 shows a possible implementation based on the circuit shown in FIG. 3 .
  • FIG. 7 shows the driving circuit 330 , the mutual capacitance model 360 of the touch screen, and the amplification circuit 310 , the control circuit 320 , the filter circuit 340 and the sampling circuit 350 in the capacitance detection circuit 300 .
  • the mutual capacitance model 360 of the touch screen is the equivalent diagram of the touch model in the screen, where Csg is the equivalent capacitance of the RX channel, Cdg is the equivalent capacitance of the drive channel TX, and the detection capacitance Cx is the capacitance between the RX channel and the TX channel. equivalent capacitance.
  • Rtx is the driving impedance of the driving circuit 330
  • 361 is the noise signal source in the display screen.
  • One end of the detection capacitor Cx is connected to the system ground, and the other end is connected to the amplifier circuit 310 .
  • the driving circuit 330 is used for generating a driving signal, and the driving signal is input to the TX channel, and an induction signal is generated on the RX channel, and the induction signal is input to the amplifying circuit 310 .
  • the voltage signal V OUT output by the amplifying circuit 310 can be used to determine the magnitude of the mutual capacitance between the TX channel and the RX channel, that is, C X .
  • the filtering circuit 340 may be, for example, an analog antialiasing filter (Analog Antialiasing Filter, AAF) with low-pass characteristics, so as to avoid aliasing of high-frequency signals or noise into the sampling circuit 150 .
  • AAF analog Antialiasing filter
  • the sampling circuit 350 is, for example, an analog-to-digital converter (Analog-to-Digital Converter, ADC) circuit, which is used to convert the voltage signal into a digital signal so that the digital system can process it.
  • the control circuit 320 can control the gear of the adjustable resistance in the amplifying circuit 310, so that the amplification factor of the amplifying circuit 310 has a larger magnification factor in the sub-period with less noise, and has a larger amplification factor in the sub-period with higher noise. smaller magnification.
  • the control circuit 320 can also control other parts in the capacitance detection circuit 300, such as the cut-off frequency of the filter circuit 340, and the like.
  • the period where the noise peak of the noise signal of the display screen is located is divided into consecutive N sub-periods, and the amplification factor of the amplifying circuit 310 in the N sub-periods is controlled by the control circuit 320, so that the amplifying circuit 310 is in the N sub-periods.
  • the amplification factor within N sub-periods is inversely proportional to the size of the noise signal in N sub-periods to avoid saturation of the amplification circuit 310 .
  • the capacitance detection circuit 300 improves the signal-to-noise ratio of capacitance detection while ensuring the effective operation of the amplifying circuit 310, and has better detection performance.
  • the adjustable resistor can be regarded as a resistor network, the resistor network includes a plurality of resistors with different resistance values, and the control circuit 320 selects the resistors by controlling a switch connected in series with each resistor.
  • the resistance values of the feedback resistors R f1 and R fN are different.
  • the control circuit 320 can control the closing and opening of the switches K1 to KN through the control signal, so as to select an appropriate feedback resistance in different sub - periods, so that the amplifier circuit 320 has a matching noise in the sub-period. gain.
  • An embodiment of the present application further provides a touch control chip, including the capacitance detection circuit in the various embodiments of the present application.
  • the embodiment of the present application further provides an electronic device, the electronic device includes: a touch screen; a display screen; and the touch chip in the above-mentioned various embodiments of the present application.
  • the electronic device in the embodiment of the present application may be a portable or mobile computing device such as a terminal device, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a game device, a vehicle-mounted electronic device, or a wearable smart device, and Electronic databases, automobiles, bank ATMs (Automated Teller Machine, ATM) and other electronic devices.
  • the wearable smart device includes full functions, large size, and can realize complete or partial functions without relying on smart phones, such as smart watches or smart glasses, etc., and only focus on a certain type of application function, which needs to cooperate with other devices such as smart phones. Use, such as various types of smart bracelets, smart jewelry and other equipment for physical monitoring.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Position Input By Displaying (AREA)

Abstract

提供了一种电容检测电路、触控芯片和电子设备，能够降低显示屏噪声对电容检测的影响。所述电容检测电路包括：放大电路，与触摸屏中的检测电容相连，用于对所述检测电容的电容信号进行放大并将其转换为电压信号，所述电压信号用于确定所述检测电容；以及，控制电路，与所述放大电路相连，用于控制所述放大电路的放大倍数，其中，显示屏的噪声信号的一个噪声峰值所在的时段包括连续的N个子时段，所述放大电路在所述N个子时段内的放大倍数与所述N个子时段内的所述噪声信号的大小呈反比，N＞1。

Description

电容检测电路、触控芯片和电子设备 技术领域
本申请实施例涉及电容检测领域，并且更具体地，涉及一种电容检测电路、触控芯片和电子设备。
背景技术
电容式传感器广泛应用于电子产品中，用来实现触摸检测。当有导体例如手指，触摸或靠近电子设备的触摸屏中的检测电极时，检测电极对应的电容会发生变化，通过检测该电容的变化量，就可以获取手指靠近或触摸检测电极的信息，从而判断用户的操作。但是，电子设备的显示屏产生的噪声，会对上述检测结果造成影响。因此，如何降低显示屏噪声对电容检测的影响，成为亟待解决的问题。
发明内容
本申请实施例提供一种电容检测电路、触控芯片和电子设备，能够降低显示屏噪声对电容检测的影响。
第一方面，提供了一种电容检测电路，包括：
放大电路，与触摸屏中的检测电容相连，用于对所述检测电容的电容信号进行放大并将其转换为电压信号，所述电压信号用于确定所述检测电容；以及，
控制电路，与所述放大电路相连，用于控制所述放大电路的放大倍数，其中，显示屏的噪声信号的一个噪声峰值所在的时段包括连续的N个子时段，所述放大电路在所述N个子时段内的放大倍数与所述N个子时段内的所述噪声信号的大小呈反比，N＞1。
在一种可能的实现方式中，所述放大电路包括运算放大器，所述运算放大器的输入端和输出端之间连接有可调电阻，所述控制电路具体用于：控制所述可调电阻的阻值，以使所述放大电路在所述N个子时段内的放大倍数与所述N个子时段内所述噪声信号的大小呈反比。
在一种可能的实现方式中，所述运算放大器为差分运算放大器，所述差分运算放大器的第一输入端和第一输出端之间连接有一个所述可调电阻，所 述差分运算放大器的第二输入端和第二输出端之间连接有一个所述可调电阻。
在一种可能的实现方式中，所述放大电路在所述噪声信号的非噪声峰值所在的时段内的放大倍数为恒定值。
在一种可能的实现方式中，所述恒定值大于或等于所述放大电路在所述N个子时段内的最大放大倍数。
在一种可能的实现方式中，N＝3或者N＝4。
在一种可能的实现方式中，所述噪声信号的噪声峰值所在的时段是根据所述显示屏的行同步信号的扫描频率确定的。
在一种可能的实现方式中，所述显示屏的行同步信号的一个扫描周期内包括一个或者两个所述噪声峰值。
在一种可能的实现方式中，所述电容检测电路还包括：滤波电路，与所述放大电路相连，用于对所述放大电路输出的所述电压信号进行滤波处理。
在一种可能的实现方式中，所述电容检测电路还包括：ADC电路，与所述滤波电路相连，用于将滤波后的所述电压信号转换为数字信号。
第二方面，提供了一种触控芯片，包括：前述第一方面以及第一方面的任一种可能的实现方式中的电容检测电路。
第三方面，提供了一种电子设备，包括：触摸屏；显示屏；以及，前述第二方面以及第二方面的任一种可能的实现方式中的触控芯片。
基于上述技术方案，将显示屏的噪声信号的噪声峰值所在的时段划分为连续的N个子时段，并通过控制电路对放大电路在N个子时段内的放大倍数进行控制，使得放大电路在N个子时段内的放大倍数与N个子时段内的该噪声信号的大小呈反比，以避免放大电路饱和。该电容检测电路在保证放大电路有效工作的同时，提高了电容检测的信噪比，具有更好的检测性能。
附图说明
图1是电容检测原理的示意图。
图2是本申请实施例的一种可能的电容检测系统的示意性结构图。
图3是本申请实施例的电容检测电路的示意性框图。
图4是噪声大小与放大倍数之间的关系的示意图。
图5是噪声大小与放大倍数之间的关系的示意图。
图6是本申请实施例的放大电路的示意图。
图7是基于图3所示的电容检测电路的一种可能的具体实现方式。
图8是基于图3所示的电容检测电路的一种可能的具体实现方式。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
图1是触摸检测的原理的示意图。图1中示出了触控面板中的横向和纵向的两层通道，采用这种图案的电容触控系统通常可以同时采用自电容和互电容这两种电容检测方式。在进行自电容检测时，触控芯片会扫描每一个横向通道和纵向通道对地的自电容的变化情况。当手指靠近或接触时，手指附近的通道的自电容会变大。在进行互电容检测时，其中一层通道作为驱动通道(TX通道)，另一层通道作为感应通道(RX通道)，触控芯片检测的是TX和RX之间的互电容的变化情况。例如图1所示，手指和其附近的横向通道C RXN-1会产生电容Cs，手指和其附近的纵向通道C TX1会产生电容Cd。由于人体是导体并且和地相连，手指触摸或接近的通道的自电容和互电容均会发生变化，触控芯片根据检测到的自电容或互电容的变化，可以计算出手指的触摸位置。
图2所示为本申请涉及的一种可能的电容检测系统的示意性结构图。如图2所示，触控面板210与触控芯片(触控IC)220连接，其中，触控IC 220包括同步控制电路221、驱动电路222、电容检测电路223。同步控制电路221用于接收显示器的行同步信号(记作Hsync信号)和场同步信号(记作Vsync信号)，并生成电容检测系统内部的相关触发信号。驱动电路222用于产生驱动信号，或称为打码信号，该打码信号可以被输入至触控板中的TX通道。电容检测电路223例如可以包括可编程增益放大器(Programmable Gain Amplifier，PGA)、具有低通特性的模拟抗混叠滤波器(Analog Antialiasing Filter，AAF)、模数转换电路(Analog to Digital Conversion Circuit，ADC)等。其中，PGA电路可以用于接收触控板中的RX通道传输过来的信号，并对其进行放大处理；AAF电路与PGA电路相连，用于滤除其接收到的电信号中所携带的干扰信号；ADC电路与AAF电路相连，用于将模拟信号转换为数字信号。
对于电子设备的屏幕，尤其是Y-OCTA屏幕来说，由于这种类型的屏幕 在材料、叠层和著作工艺上都与传统的LCD On-cell屏幕不同，导致主要的面板参数有较大变化，使得屏幕中的显示驱动芯片(Display Driver Integrated Circuit，DDIC)带来的显示屏噪声显著增加。显示屏噪声对触摸屏中的电容检测电路会造成影响，从而使电容检测电路对自电容和互电容的检测灵敏度显著下降。
为此，本申请提供一种电容检测电路，能够降低显示屏噪声对触摸屏的电容检测的影响。
图3是本申请实施例的电容检测电路的示意性框图。如图3所示，电容检测电路300包括放大电路310和控制电路320。
放大电路310与触摸屏(也称触控屏)中的检测电容C X相连，用于对检测电容C X的电容信号进行放大并将其转换为电压信号。其中，该电压信号用于确定该检测电容C X。
控制电路320与放大电路310相连，用于控制放大电路310的放大倍数。其中，显示屏的噪声信号的一个噪声峰值所在的时段包括连续的N个子时段，放大电路310在该N个子时段内的放大倍数与该N个子时段内的噪声信号的大小呈反比，N＞1。
应理解，本申请实施例中所述的显示屏和触控屏，可以分别认为是电子设备的屏幕中的显示层和触控层。电路设备的屏幕通常包括显示层和触控层，分别用于实现显示功能和触控功能。
显示屏在进行扫描时，扫描信号例如显示屏的行同步信号，与显示屏产生的噪声信号之间相关联。其中，行同步信号是按照一定规律变化的，例如周期性变化，而显示屏的噪声信号与该显示屏的行同步信号之间的相位差基本不变，因此显示屏产生的噪声信号也会按照一定规律变化。
该实施例中，将显示屏产生的噪声信号在时间上进行划分，例如，该噪声信号的噪声峰值所在的时段划分为N个子时段，即T1、T2、……、Ti、……T N。在这N个子时段中，噪声信号是变化的，因此，控制电路可以根据该N个子时段内的噪声信号的大小，控制放大电路310分别在该N个子时段内的放大倍数。其中，噪声信号越大的子时段内，放大电路的放大倍数越小；噪声信号越小的子时段内，放大电路的放大倍数越大。
在进行电容检测时，可以基于例如显示屏的行同步信号的传输，确定在哪些时段会产生噪声信号，从而根据预先为不同子时段设定好的对应的放大 倍数，对放大电路310的放大倍数进行调整。
应理解，本申请实施例中所述的噪声峰值所在的时段，是指显示屏的噪声从低电平向高电平转换的起始时刻，至从高电平向低电平转换的结束时刻之间的时段。例如图4中示出了三个噪声峰值，其中每个噪声峰值包括T1至T6所在的时段；又例如图5中示出了三个噪声峰值，其中，第一个噪声峰值和第三个噪声峰值均包括T1至T6所在的时段，第二个噪声峰值包括T8至T12所在的时段。
举例来说，如图4所示，假设N＝6，显示屏产生的噪声信号的噪声峰值所在的时段被划分为子时段T1、T2、T3、T4、T5和T6。其中，在一个噪声峰值内，显示屏在子时段T3内产生的噪声信号最大，在子时段T1和T6内产生的噪声信号最小。控制电路320根据显示屏在子时段T1、T2、T3、T4、T5和T6内产生的噪声信号的大小，即噪声信号的电压幅值，控制放大电路310在子时段T1、T2、T3、T4、T5和T6内的放大倍数与噪声信号的大小成反比。如图4所示，作为示例，当放大电路310在子时段T1、T2、T3、T4、T5和T6内的放大倍数分别为A1、A2、A3、A4、A5和A6时，可以控制A1＝A6＞A2＝A5＞A4＞A3。
图4所示为在一个行同步扫描周期内存在一个噪声峰值的情况，在实际应用中，一个行同步信号的扫描周期内也可以存在两个或以上噪声峰值，并且每个噪声峰值所在的时段内的噪声信号的变化情况可以相同也可以不同。因此，可以根据各个噪声峰值的特性，将各个噪声峰值所在的时段划分为相同或者不同数量N的子时段。例如一个行同步信号的扫描周期中的第一个噪声峰值所在的时段包括N1个子时段，第二个噪声峰值所在的时段包括N2个子时段。
例如图5所示，在一个行同步扫描周期内存在两个噪声峰值。前一个噪声峰值所在的时段包括N1个子时段，N1＝6，分别为T1、T2、T3、T4、T5和T6；后一个噪声峰值所在的时段包括N2个子时段，N2＝5，分别为T8、T9、T10、T11和T12。类似地，控制电路320控制放大电路310在子时段T1、T2、T3、T4、T5和T6内的放大倍数与噪声信号的大小成反比；以及控制电路320控制放大电路310在子时段T8、T9、T10、T11和T12内的放大倍数与噪声信号的大小成反比。如图5所示，作为示例，当放大电路310在子时段T1、T2、T3、T4、T5和T6内的放大倍数分别为A1、A2、A3、 A4、A5和A6时，可以控制A1＝A6＞A2＝A5＞A4＞A3；当放大电路310在子时段T8、T9、T10、T11和T12内的放大倍数A8、A9、A10、A11和A12可以满足时，可以控制A8＝A12＞A9＞A11＞A10。
可见，将显示屏的噪声信号的噪声峰值所在的时段划分为连续的N个子时段，并通过控制电路320对放大电路310在N个子时段内的放大倍数进行控制，使得放大电路310在N个子时段内的放大倍数与N个子时段内的该噪声信号的大小呈反比，以避免放大电路310饱和。这样，电容检测电路300在保证放大电路310有效工作的同时，提高了电容检测的信噪比，具有更好的检测性能。
本申请实施例中，N＞1，从而使电容检测电路300对噪声变化的适配能力更强，并可以适用于一个行同步信号的扫描周期内存在多个噪声峰值的情况。
其中，N较大时会更加实现的复杂度，N较小时又无法更好地适配噪声变化，因此，优选地，N＝3或者N＝4。
本申请实施例对如何确定N个子时段中每个子时段的噪声信号的大小不做限定。例如，可以根据该子时段内某个时刻的噪声信号的大小来确定；又例如，可以根据该子时段内多个时刻的噪声信号的均值来确定。本申请对此不做限定。
N个子时段被的噪声信号的大小与放大电路310在N个子时段内的放大倍数之间可以是理想的倒数关系，例如，在图4中，子时段T1的噪声信号的大小与子时段T2的噪声信号的大小，可以等于放大电路310在子时段T2的放大倍数A2与放大电路310在子时段T1的放大倍数A1之间的比值，但本申请并不限于此，在子时段T1的噪声信号的小于子时段T2的噪声信号的大小的情况下，只要使得A1＞A2即可。
放大电路310在显示屏的噪声信号的非噪声峰值所在的时段内的放大倍数例如可以是恒定值。该恒定值例如可以大于或等于放大电路310在N个子时段的最大放大倍数。例如，在图4或图5中的非噪声峰值所在的时段T7，放大电路310的放大倍数可以等于放大电路310在N个子时段内的最大放大倍数，即与子时段T1和T6对应的放大倍数相等；也可以大于放大电路310在N个子时段的放大倍数，即大于子时段T1和T6对应的放大倍数。又例如在图5中的非噪声峰值所在的时段T13，放大电路310的放大倍数可以等 于放大电路310在N2个子时段内的最大放大倍数，即与子时段T8和T12对应的放大倍数相等；也可以大于放大电路310在N2个子时段的放大倍数，即大于子时段T8和T12对应的放大倍数。
本申请实施例对如何确定噪声峰值不做任何限定。该噪声信号的噪声峰值所在的时段是根据显示屏的行同步信号的扫描频率确定的。例如，可以通过对电容检测电路300的输出信号进行检测，获取显示屏的噪声信号的噪声峰值与行同步信号之间的相位关系，进一步还可以获取该噪声峰值的大小。从而确定放大电路310在该噪声峰值所在的时段内的N个子时段对应的放大倍数。
放大电路310的输入端与检测电容Cx相连，并输出与检测电容Cx相关联的电压信号。放大电路310的放大倍数被调整后，可以基于该放大倍数输出放大后的该电压信号。检测电容Cx的电容发生变化时，放大电路310输出的该电压信号也会发生变化，因此，根据放大电路310输出的电压信号的大小，就可以判断检测电容Cx的大小或者变化量。也就是说，放大电路310可以将检测电容Cx的电容信号转换为电压信号并对其进行放大，从而实现对检测电容Cx的检测。
控制电路320与放大电路310相连，用于控制放大电路310的放大倍数。其中，放大电路310在显示屏噪声较小的子时段具有相对较大的放大倍数，以提高电容检测的SNR；而放大电路310在显示屏噪声较大的子时段具有相对较小的放大倍数，以避免放大电路310饱和，保证放大电路310的有效工作。因此，电容检测电路300在保证放大电路310有效工作的同时，提高了电容检测的信噪比，具有更好的检测性能。
本申请实施例中的电容检测电路可以用于互容检测或者自容检测，该检测电容Cx可以是TX通道或者RX通道对地的自电容，或者检测电容Cx是TX通道和RX通道之间的互电容。TX通道用于输入驱动信号。RX通道用于感应该驱动信号并产生检测信号。以下仅以互容检测为例进行描述。
可选地，在一种实现方式中，放大电路310包括运算放大器，例如放大电路310可以是可编程增益放大器(Programmable Gain Amplifier，PGA)。其中，该运算放大器的输入端和输出端之间连接有的可调电阻，也称可变电阻。其中，控制电路320具体用于：控制该可调电阻的阻值，以使放大电路310在上述N个子时段内的放大倍数与N个子时段内该噪声信号的大小呈反 比。
例如图6所示，该运算放大器可以是一个差分运算放大器，该差分运算放大器可以将检测电容Cx的电容信号转换为电压信号V OUT，该电压信号V OUT为差分信号，具有更好的信噪比。该差分运算放大器的第一输入端和第一输出端之间连接有一个可调电阻R f1，所述差分运算放大器的第二输入端和第二输出端之间连接有一个可调电阻R f2。其中，优选地，R f1与R f2相等。
R f1和R f2可以具有多个档位，多个档位对应多个阻值，这多个阻值分别用来匹配N个子时段内的噪声信号。其中，在噪声信号较大的子时段内，R f1和R f2会被调节至较小的阻值，以使放大电路310具有较小的放大倍数；而在噪声信号较小的子时段内，R f1和R f2会被调节至较大的阻值，以使放大电路310具有较大的放大倍数。
该实施例中，在运算放大器的输入端和输出端之间，还可以设置有分别与反馈电阻R f1和反馈电阻R f2并联的反馈电容C f1和反馈电容C f2。
可选地，电容检测电路300还包括：滤波电路340，与放大电路310相连，用于对放大电路310输出的电压信号进行滤波处理。
可选地，电容检测电路300还包括：ADC电路350，与滤波电路340相连，用于将滤波后的电压信号转换为数字信号。
图7示出了基于图3所示的电路的一种可能的实现方式。图7示出了驱动电路330、触摸屏的互容模型360、以及电容检测电路300中的放大电路310、控制电路320、滤波电路340和采样电路350。触摸屏的互容模型360即屏幕中的触控模型的等效图，其中Csg为RX通道的等效电容，Cdg为驱动通道TX的等效电容，检测电容Cx为RX通道和TX通道之间的等效电容。Rtx为驱动电路330的驱动阻抗，361为显示屏中的噪声信号源。检测电容Cx的一端接系统地，另一端与放大电路310相连。当有手指触摸时，触摸位置的RX通道和TX通道之间的互电容会变大，电容检测电路300通过检测该互电容即Cx的电容变化，就可以获取用户的触摸信息。
驱动电路330用于产生驱动信号，该驱动信号被输入TX通道，并在RX通道上会产生一个感应信号，该感应信号被输入至放大电路310。放大电路310输出的电压信号V OUT可以用来确定该TX通道和该RX通道之间的互电容即C X的大小。滤波电路340例如可以是具有低通特性的模拟抗混叠滤波器(Analog Antialiasing Filter，AAF)，以避免高频信号或噪声混叠到采样电 路150中。采样电路350例如为模数转换(Analog-to-Digital Converter，ADC)电路，用于将电压信号转化为数字信号，以便于数字系统对其进行处理。控制电路320可以控制放大电路310中的可调电阻的档位，以使放大电路310的放大倍数在噪声较小的子时段内具有较大的放大倍数，而在噪声较大的子时段内具有较小的放大倍数。此外，控制电路320还可以控制电容检测电路300中的其他部分，例如滤波电路340的截止频率等。
可见，将显示屏的噪声信号的噪声峰值所在的时段划分为连续的N个子时段，并通过控制电路320对放大电路310在N个子时段内的放大倍数进行控制，使得放大电路310在N个子时段内的放大倍数与N个子时段内的该噪声信号的大小呈反比，以避免放大电路310饱和。这样，电容检测电路300在保证放大电路310有效工作的同时，提高了电容检测的信噪比，具有更好的检测性能。
应理解，可调电阻可以看作是一个电阻网络，该电阻网络中包括具有不同阻值的多个电阻，控制电路320通过控制与每个电阻串联的开关，对该电阻进行选通。例如，图8中所示的放大电路310，反馈电阻R f1和R fN的阻值不同。可以理解，控制电路320可以通过控制信号控制开关K1至K N的闭合与断开，从而在不同的子时段内选择合适的反馈电阻，以使放大电路320在该子时段具有与噪声相匹配的放大倍数。
本申请实施例还提供一种触控芯片，包括上述本申请各种实施例中的电容检测电路。
本申请实施例还提供了一种电子设备，该电子设备包括：触摸屏；显示屏；以及，上述本申请各种实施例中的触控芯片。
作为示例而非限定，本申请实施例中的电子设备可以为终端设备、手机、平板电脑、笔记本电脑、台式机电脑、游戏设备、车载电子设备或穿戴式智能设备等便携式或移动计算设备，以及电子数据库、汽车、银行自动柜员机(Automated Teller Machine，ATM)等其他电子设备。该穿戴式智能设备包括功能全、尺寸大、可不依赖智能手机实现完整或部分的功能，例如：智能手表或智能眼镜等，以及只专注于某一类应用功能，需要和其它设备如智能手机配合使用，如各类进行体征监测的智能手环、智能首饰等设备。
需要说明的是，在不冲突的前提下，本申请描述的各个实施例和/或各个实施例中的技术特征可以任意的相互组合，组合之后得到的技术方案也应落 入本申请的保护范围。
应理解，本申请实施例中的具体的例子只是为了帮助本领域技术人员更好地理解本申请实施例，而非限制本申请实施例的范围，本领域技术人员可以在上述实施例的基础上进行各种改进和变形，而这些改进或者变形均落在本申请的保护范围内。
以上所述，仅为本申请的具体实施方式，但本申请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申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (12)

  1. 一种电容检测电路，其特征在于，包括：
    放大电路，与触摸屏中的检测电容相连，用于对所述检测电容的电容信号进行放大并将其转换为电压信号，所述电压信号用于确定所述检测电容；以及，
    控制电路，与所述放大电路相连，用于控制所述放大电路的放大倍数，其中，显示屏的噪声信号的一个噪声峰值所在的时段包括连续的N个子时段，所述放大电路在所述N个子时段内的放大倍数与所述N个子时段内的所述噪声信号的大小呈反比，N＞1。
  2. 根据权利要求1所述的电容检测电路，其特征在于，所述放大电路包括运算放大器，所述运算放大器的输入端和输出端之间连接有可调电阻，所述控制电路具体用于：
    控制所述可调电阻的阻值，以使所述放大电路在所述N个子时段内的放大倍数与所述N个子时段内所述噪声信号的大小呈反比。
  3. 根据权利要求2所述的电容检测电路，其特征在于，所述运算放大器为差分运算放大器，
    所述差分运算放大器的第一输入端和第一输出端之间连接有一个所述可调电阻，所述差分运算放大器的第二输入端和第二输出端之间连接有一个所述可调电阻。
  4. 根据权利要求1至3中任一项所述的电容检测电路，其特征在于，所述放大电路在所述噪声信号的非噪声峰值所在的时段内的放大倍数为恒定值。
  5. 根据权利要求4所述的电容检测电路，其特征在于，所述恒定值大于或等于所述放大电路在所述N个子时段内的最大放大倍数。
  6. 根据权利要求1至5中任一项所述的电容检测电路，其特征在于，N＝3或者N＝4。
  7. 根据权利要求1至6中任一项所述的电容检测电路，其特征在于，所述噪声信号的噪声峰值所在的时段是根据所述显示屏的行同步信号的扫描频率确定的。
  8. 根据权利要求1至7中任一项所述的电容检测电路，其特征在于，所述显示屏的行同步信号的一个扫描周期内包括一个或者两个所述噪声峰 值。
  9. 根据权利要求1至8中任一项所述的电容检测电路，其特征在于，所述电容检测电路还包括：
    滤波电路，与所述放大电路相连，用于对所述放大电路输出的所述电压信号进行滤波处理。
  10. 根据权利要求9所述的电容检测电路，其特征在于，所述电容检测电路还包括：
    模数转换ADC电路，与所述滤波电路相连，用于将滤波后的所述电压信号转换为数字信号。
  11. 一种触控芯片，其特征在于，包括根据权利要求1至10中任一项所述的电容检测电路。
  12. 一种电子设备，其特征在于，包括：
    触摸屏；
    显示屏；以及，
    根据权利要求11所述的触控芯片。
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