WO2014056313A1 - 信号处理及前置放大电路和触摸屏 - Google Patents

信号处理及前置放大电路和触摸屏 Download PDF

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Publication number
WO2014056313A1
WO2014056313A1 PCT/CN2013/073800 CN2013073800W WO2014056313A1 WO 2014056313 A1 WO2014056313 A1 WO 2014056313A1 CN 2013073800 W CN2013073800 W CN 2013073800W WO 2014056313 A1 WO2014056313 A1 WO 2014056313A1
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WO
WIPO (PCT)
Prior art keywords
signal
preamplifier
pixel point
touch screen
signal processing
Prior art date
Application number
PCT/CN2013/073800
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English (en)
French (fr)
Inventor
黄忠守
Original Assignee
上海天马微电子有限公司
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Publication of WO2014056313A1 publication Critical patent/WO2014056313A1/zh

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Classifications

    • 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
    • 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
    • G06F3/0445—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer

Definitions

  • a capacitive touch panel (CTP) mainly has a self-capacitance inductive touch screen and a mutual capacitance inductive touch screen.
  • the mutual capacitance inductive touch screen includes a plurality of driving lines and a plurality of sensing lines, and the driving lines and the sensing lines are placed at an intersection, and mutual capacitance is formed at intersections of the driving lines and the sensing lines.
  • the mutual capacitance inductive touch screen can include mutual capacitance arranged in an array.
  • the driving line emits a pulse signal
  • the sensing line generates a current signal by sensing the pulse signal.
  • the sensing line outputs a stable background signal, and the background signal is converted into a stable charge signal after passing through the charge amplifier circuit, and the stable charge signal is converted into a stable after passing through the band pass filter.
  • the output voltage is not touched.
  • the sensing line of the mutual capacitance inductive touch screen When the human body touches the touch screen, the human body is grounded, and the finger and the touch screen form an equivalent capacitance.
  • the pulse signal from the driving line can flow into the ground through the equivalent capacitance.
  • the sensing line generates a current signal change, and the resulting output is output.
  • the voltage also changes and the touch operation is detected. It can be seen from the above that the sensing line of the mutual capacitance inductive touch screen generates a background signal when the touch screen is not touched, and after the touch screen is touched, the sensing line generates a current signal superimposed with the background signal. In the current signal, the current change portion with respect to the background signal is the current value that actually represents the touch signal.
  • the charge amplifier circuit is actually a specific application of the integration circuit.
  • the circuit can integrate the received current signal to generate a corresponding charge signal.
  • the smaller the capacitance of the integrating capacitor of the charge amplifier circuit the larger the output voltage and the larger the gain.
  • the integrated capacitance of the charge amplifier circuit needs to be set to a smaller capacitance value.
  • the current value of the background signal tends to be large, and if the capacitance value of the integrating capacitor in the charge amplifier circuit is small, the charge amplifier circuit is easily saturated. After the charge amplifier circuit is saturated, the output voltage does not change whether the touch screen is touched or not, and the touch operation cannot be detected.
  • a signal processing and preamplifier circuit for a touch screen comprising: a compensation current generating unit adapted to output a compensation current signal to eliminate pixel output current of the touch screen At least part of the background signal in the signal, the background signal is a pixel point output current signal when not touched; the preamplifier, the negative phase input end is adapted to receive the pixel point output current signal and the compensation current signal, the positive phase input end Suitable for receiving a reference voltage; a feedback impedance adapted to connect the negative phase input and the output of the preamplifier.
  • the compensation current generating unit includes: a storage unit, configured to store a background signal corresponding to all the pixel points in the touch screen; and a current output unit, configured to search the storage unit according to coordinates of the current pixel point a background signal corresponding to the pixel, and generating a compensation current signal according to the found background signal; a charge feeding impedance adapted to output the compensation current signal to the preamplifier Negative phase input.
  • the current output unit is adapted to search for a background signal corresponding to the pixel point from the LOOKUP TABLE in the storage unit according to the coordinates of the current pixel point.
  • the preamplifier is a charge amplifier, and the charge feeding impedance and the feedback impedance are implemented by a capacitor; or the preamplifier is a voltage amplifier or a current-voltage converter, and the charge is fed into the impedance and The feedback impedance is achieved by a resistor.
  • the storage unit stores a waveform or an integrated charge amount of a background signal corresponding to all the pixel points.
  • the storage unit stores an actual waveform of the background signal corresponding to all the pixel points or a compressed form of the actual waveform.
  • the preamplifier is a charge amplifier, and the compensation current signal is synchronous with the background signal and opposite in phase, and the integrated charge of the compensation current signal is 0.5-1.5 times of the integrated charge of the background signal.
  • the preamplifier is a voltage amplifier or a current-voltage converter, and the compensation current signal is synchronized with the background signal and opposite in phase, and the compensation current signal F2i and the background signal Fli satisfy:
  • the signal processing and preamplifier circuit further includes: at least one feedback branch; each of the at least one feedback branch is disposed at a negative phase input end of the preamplifier and Between the outputs; each of the feedback branches includes: a series connected switch and a branch feedback impedance.
  • a signal processing and preamplifier circuit for a touch screen comprising: a preamplifier, a negative phase input end adapted to receive a pixel output current signal of the touch screen, a positive phase input end adapted to receive a reference voltage; a feedback impedance, suitable a negative phase input terminal and an output terminal connected to the preamplifier; at least one feedback branch, wherein each of the feedback branches is disposed between the negative phase input terminal and the output terminal of the preamplifier,
  • One feedback branch includes: a series connected switch and a branch feedback impedance.
  • the preamplifier is a charge amplifier, and the feedback impedance and the branch feedback impedance are implemented by a capacitor; or the preamplifier is a voltage amplifier or a current-voltage converter, the feedback impedance and the branch The feedback impedance is achieved by a resistor.
  • the signal processing and preamplifier circuit further includes: a compensation current generating unit, configured to output a compensation current signal to eliminate at least part of the background signal in the pixel output current signal, where the background signal is The pixel point outputs a current signal when touched; the negative phase input of the preamplifier is further adapted to receive the compensation current signal.
  • the compensation current generating unit includes: a storage unit, configured to store a background signal corresponding to all the pixel points in the touch screen; and a current output unit, configured to search the storage unit according to coordinates of the current pixel point a background signal corresponding to the pixel, and generating a compensation current signal according to the found background signal; and a charge feeding impedance adapted to output the compensation current signal to the negative phase input end of the preamplifier.
  • the current output unit is adapted to search for a background signal corresponding to the pixel point from the LOOKUP TABLE in the storage unit according to the coordinates of the current pixel point.
  • the preamplifier is a charge amplifier, and the charge feeding impedance and the feedback impedance are implemented by a capacitor; or the preamplifier is a voltage amplifier or a current-voltage converter, and the charge is fed into the impedance and The feedback impedance is achieved by a resistor.
  • the preamplifier is a charge amplifier, and the compensation current signal is synchronous with the background signal and opposite in phase, and the integrated charge of the compensation current signal is 0.5-1.5 times of the integrated charge of the background signal.
  • the preamplifier is a voltage amplifier or a current-voltage converter, and the compensation current signal is synchronized with the background signal and opposite in phase, and the compensation current signal F2i and the background signal Fli satisfy:
  • a touch screen includes the above signal processing and preamplifying circuit.
  • the touch screen includes a plurality of driving lines and a plurality of sensing lines, and the signal processing and preamplifying circuits are electrically connected to the sensing lines.
  • the driving line and the sensing line are located in different layers, and are separated by an insulating layer.
  • the driving line and the sensing line are located in the same layer.
  • one sensing line is connected to one of the signal processing and preamplifying circuits.
  • all of the sensing lines are connected in common to one of the signal processing and preamplifier circuits.
  • FIG. 1 is a schematic structural diagram of a signal processing and preamplifier circuit according to an embodiment of the present invention
  • FIG. 2 is a schematic diagram of a pixel point output current signal according to the present invention
  • FIG. 3 is a signal processing and preamplification according to an embodiment of the present invention
  • FIG. 4 is a schematic diagram of another embodiment of a signal processing and preamplifier circuit according to an embodiment of the present invention
  • FIG. 6 is a schematic diagram of another embodiment of a signal processing and preamplifier circuit according to an embodiment of the present invention
  • FIG. 7 is a schematic diagram showing another relationship between a pixel point output current signal and a compensation signal according to the present invention
  • FIG. 8 is a schematic structural diagram of a signal processing and preamplifier circuit according to Embodiment 2 of the present invention
  • FIG. 10 is a schematic structural diagram of a signal processing and preamplifier circuit according to Embodiment 2 of the present invention
  • FIG. 10 is a schematic structural diagram of a signal processing and preamplifier circuit according to Embodiment 2 of the present invention
  • FIG. 10 is a schematic structural diagram of a signal processing and preamplifier circuit according to Embodiment 3 of the present invention.
  • Another structure of the preamplifier circuit 12 is a schematic structural view of a touch screen of the present invention
  • FIG. 13 is another schematic structural view of the touch screen of the present invention.
  • the signal processing and preamplifier circuit is used for the touch screen 5, and includes: a compensation current generating unit 1 adapted to output a compensation current signal. A2, to eliminate at least part of the background signal in the pixel output current signal A1, the background signal is a pixel point output current signal of the touch screen 5 when not touched; the preamplifier 3, the negative phase input end is adapted to receive the pixel point The output current signal A1 and the compensation current signal A2 are adapted to receive the reference voltage VF (generally grounded); the feedback impedance 4 is adapted to be connected to the negative phase input terminal and the output terminal of the preamplifier 3.
  • the touch screen 5 can be a mutual capacitance sensing type touch screen.
  • the mutual capacitance inductive touch screen comprises a plurality of driving lines and a plurality of sensing lines, wherein the driving lines and the sensing lines are placed at intersection, and the intersections of the driving lines and the sensing lines form pixel points, that is, mutual capacitance.
  • the mutual capacitance inductive touch screen includes mutual capacitance arranged in an array.
  • the touch screen 5 in FIG. 1 includes a first driving line 52, a second driving line 53, a first sensing line 54, and a second sensing line 55.
  • a first pixel point 524 is formed at an intersection of the first driving line 52 and the first sensing line 54; a second pixel point 525 is formed at an intersection of the first driving line 52 and the second sensing line 55; the second driving line 53 and the first A third pixel point 534 is formed at the intersection of the sensing line 54; a fourth pixel point 535 is formed at the intersection of the second driving line 53 and the second sensing line 55; the first pixel point 524, the second pixel point 525, the third The pixel point 534 and the fourth pixel point 535 are arranged in an array.
  • Figure 2 shows the relationship between pixel point output current signals when not touched and touched. As can be seen from FIG.
  • the pixel point output current signal at the time of touch may be larger than the amplitude of the pixel point output current signal when not touched, or may be smaller than the amplitude of the pixel point output current signal when not touched.
  • the compensation current generating unit 1 may include: a storage unit 11 adapted to store a background signal corresponding to all pixel points in the touch screen; and a current output unit 12 adapted to select a coordinate according to a current pixel point. Finding a background signal corresponding to the pixel in the storage unit, and generating a compensation current signal A2 according to the found background signal; the charge feeding impedance 2 is adapted to output the compensation current signal A2 to the preamplifier Negative phase input.
  • the storage unit 11 stores the coordinates of the pixel and the corresponding background signal. That is to say, the background signal corresponding to the pixel point can be found according to the coordinates of the pixel point, and the correspondence relationship can be realized by the mapping table LOOKUP TABLE.
  • the coordinates may be defined according to the drive line and the sense line where the pixel points are located. For example, the first coordinate of the first pixel point 524 in FIG. 1 is (4, 2), the second coordinate of the second pixel point 525 is (5, 2), and the third coordinate of the third pixel point 534 is (4, 3), the fourth coordinate of the fourth pixel point 535 is (5, 3).
  • the storage unit 11 can store the waveform or integrated charge amount of the background signal corresponding to all the pixel points.
  • the waveform of the background signal is a waveform of a pixel point output current signal when the touch screen 5 is not touched.
  • the waveform may be an actual waveform or a compressed form of the actual waveform.
  • Figure 4 shows the relationship between the actual waveform of the background signal, the integrated charge of the background signal, and the compressed form of the actual waveform of the background signal. Wherein, the actual waveform of the background signal and the integrated charge of the compressed form should be equal.
  • the current output unit 12 can find the background signal corresponding to the pixel from the LOOKUP TABLE in the storage unit 11 according to the coordinates of the current pixel.
  • the current output unit 12 determines the coordinates of the pixel point at which the pixel point output current signal is currently generated, and searches for the corresponding pixel point from the storage unit 11 according to the coordinates of the pixel point.
  • the background signal and generates a compensation current signal based on the found background signal.
  • the current output unit 12 can determine the coordinates of the pixel point at which the pixel point output current signal is currently generated according to the touch screen driving circuit.
  • the scanning order of the four pixel points as described in FIG. 1 of the driving circuit arrangement is: first pixel point 524 and second pixel point 525, third pixel point 534 and fourth pixel point 535, respectively.
  • the first pixel point 524 After the first driving line 52 receives the driving signal, the first pixel point 524 outputs a current signal through the first sensing line 54 to the negative phase input terminal of the amplifier 3; the second pixel point 525 passes through the second sensing line 55 to the preamplifier The negative phase input of 3 outputs a current signal.
  • the second driving line 53 receives the driving signal, the third pixel point 534 outputs a current signal through the first sensing line 54 to the negative phase input terminal of the amplifier 3; the fourth pixel point 535 passes through the second sensing line 55 to the preamplifier The negative phase input of 3 outputs a current signal.
  • the current output unit 12 searches for the background signal of the first pixel point 524 according to the first coordinate of (4, 2).
  • the preamplifier 3 may be a charge amplifier 31.
  • the charge feed impedance 2 is realized by the charge feed capacitor Cref
  • the feedback impedance 4 is realized by the first capacitor Cfl.
  • the compensation current signal is synchronized with the background signal and opposite in phase, and the integrated charge of the compensation current signal is 0.5-1.5 times the integrated charge of the background signal. As shown in FIG.
  • the compensation current generating unit 1 can generate a first compensation current signal, wherein the first compensation current signal is a one-wave pulse signal, and the square wave pulse signal is synchronized with a pixel point output current signal and is opposite in phase, the square wave pulse signal
  • the integrated charge is 1-1.5 times of the integrated charge of the background signal. Under this condition, at least part of the background signal in the pixel output current signal is eliminated, and the first capacitor Cfl can select a capacitor with a smaller capacitance value, thereby obtaining a comparison Great gain.
  • the compensation current generating unit 1 can also generate a second compensation current signal, wherein the second compensation current signal is a phase opposite signal of the background signal, and the two are synchronized and the integrated electric charge is the same. Under this condition, the pixel output current signal All the background signals in the number are eliminated, and the first capacitor Cfl can also select a capacitor with a smaller capacitance value, thereby obtaining a larger gain. As shown in FIG. 7, it is assumed that the pixel point output current signal at the time of touch is smaller than the amplitude of the pixel point output current signal when not touched, and the integrated charge of the pixel point output current signal when not touched is the integral charge of the background signal.
  • the compensation current generating unit 1 can generate a first compensation current signal, wherein the first compensation current signal is a one-wave pulse signal, and the square wave pulse signal is synchronized with a pixel point output current signal and is opposite in phase, the square wave pulse signal
  • the integrated charge is 0.5-1 times of the integrated charge of the background signal. Under this condition, at least part of the background signal in the pixel point output current signal is eliminated, and the first capacitor Cfl can select a capacitor having a smaller capacitance value, thereby obtaining a comparison Great gain.
  • the compensation current generating unit 1 can also generate a second compensation current signal, wherein the second compensation current signal is a phase opposite signal of the background signal, and the two are synchronized and the integrated electric charge is the same.
  • the preamplifier 3 can also be implemented by a voltage amplifier or a current-to-voltage converter.
  • the charge feed impedance 2 and the feedback impedance 4 are realized by a resistor, and the compensation current signal F2i is synchronized with the background signal Fli and has an opposite phase, and satisfies the following formula:
  • the second embodiment of the present invention provides a signal processing and preamplifier circuit, and the signal processing and preamplifier circuit is used for the touch screen 5, including: a preamplifier 3, and a negative phase input terminal is suitable for Receive pixel point output current signal, positive phase
  • the input end is adapted to receive the reference voltage VF (generally grounded);
  • the feedback impedance 4 is adapted to be connected to the negative phase input terminal and the output terminal of the preamplifier 3; at least one feedback branch, wherein each feedback branch 6 Both are disposed between the negative phase input terminal and the output terminal of the preamplifier 3, and each of the feedback branches includes: a serially connected switch 61 and a branch feedback impedance 62.
  • the touch screen described in the second embodiment may be a mutual capacitance inductive touch screen.
  • the switch 61 can be realized by a MOS transistor, and the MOS transistor is turned on and off to realize opening and closing of the switch 61.
  • the negative phase input terminal of the preamplifier 3 is connected to the output terminal of the preamplifier 3 through the feedback impedance 4; when the switch 61 is closed, the branch feedback impedance 62 and the feedback impedance 4 are connected in parallel, and the negative phase of the preamplifier 3
  • the input is connected to the output of the preamplifier 3 via a shunt feedback impedance 62 and a feedback impedance 4 in parallel.
  • the closing and opening of the switch 61 can be set according to actual needs, for example, according to the needs of the touch screen, or according to the state of the preamplifier 3, and the switch 61 is closed if the preamplifier 3 is saturated.
  • the feedback branch is schematically illustrated as one, but it can be understood that the number of the feedback branches may be one, two, three or more.
  • the branch feedback impedance 62 in the feedback branch may be the same or different.
  • the preamplifier 3 may be a charge amplifier 31, and the switch 61 may be a first MOS transistor S1.
  • the preamplifier 3 is a charge amplifier
  • the feedback impedance 4 is achieved by the first capacitor Cfl
  • the branch feedback impedance 62 is achieved by the second capacitor CG.
  • the first MOS transistor S1 is turned off, the negative phase input terminal of the preamplifier 3 is connected to the output terminal of the preamplifier 3 only through the first capacitor Cfl.
  • the charge amplifier 31 and the first capacitor Cfl constitute the first charge amplifier circuit.
  • the second capacitor CG is connected in parallel with the first capacitor Cfl, and the negative phase input terminal of the preamplifier 3 passes through the second capacitor CG and the first capacitor connected in parallel.
  • Cfl is connected to the output of the preamplifier 3, in which case the charge amplifier 31, the first capacitor Cfl and the second capacitor C£2 constitute a second charge amplifier circuit.
  • the integrated capacitance of the second charge amplifier circuit changes as compared with the capacitance of the integrated capacitance of the first charge amplifier circuit.
  • the gain and signal-to-noise ratio can be adjusted by changing the integrated capacitance to meet the actual design requirements. As shown in FIG.
  • a third embodiment of the present invention provides a signal processing and preamplifier circuit.
  • the signal processing and preamplifier circuit is used for the touch screen 5, and includes: a compensation current generating unit 1, a preamplifier 3, and a feedback. Impedance 4 and at least one feedback branch.
  • Each of the at least one feedback branch 6 is disposed between the negative phase input of the preamplifier 3 and the output of the preamplifier 3; each of the feedback branches 6 includes: The series connected switch 61 and the branch feedback impedance 62.
  • the compensation current generating unit 1 includes: a storage unit 11 adapted to store a background signal corresponding to all pixel points in the touch screen; and a current output unit 12 adapted to be from the storage unit according to coordinates of a current pixel point Finding a background signal corresponding to the pixel, and generating a compensation current signal according to the found background signal; the charge feeding impedance 2 is adapted to output the compensation current signal to a negative phase input end of the preamplifier.
  • the preamplifier 3 is a charge amplifier 31, the switch 61 is a first MOS transistor S1, and the charge feed impedance 2, the feedback impedance 4, and the branch feedback impedance 62 are capacitances.
  • the preamplifier is a voltage amplifier or a current-to-voltage converter
  • the charge feed impedance 2, the feedback impedance 4, and the branch feedback impedance 62 are resistors.
  • the output end of the preamplifier circuit may also be connected in series with a band pass filter.
  • the technical solution of the present invention further provides a touch screen comprising the signal processing and preamplifying circuit described in the above embodiments.
  • the touch screen includes a plurality of driving lines and a plurality of sensing lines, and the signal processing and preamplifying circuits are electrically connected to the sensing lines.
  • the negative phase input terminal of the preamplifier of the signal processing and preamplifier circuit is electrically connected to the sensing line through the current output end of the pixel.
  • the driving line and the sensing line are located in different layers, and are separated by an insulating layer. The drive line and the sense line are on the same layer.
  • the signal processing and preamplifying circuit may be located on a substrate where the driving line and the sensing line are located, or may be outside the substrate.
  • all of the sensing lines can be connected to one of the signal processing and preamplifying circuits, as shown in FIG.
  • each sensing line is connected to the signal processing and preamplifying circuit through a switch 51, and the switch 51 is closed when the sensing line outputs a current signal.
  • the scanning mode of all the pixels is: the driving line is progressively scanned, and the sensing line outputs the current signal column by column.
  • one sensing line can be connected to one of the signal processing and preamplifying circuits, as shown in FIG. At this time, the scanning mode of all the pixels is: the driving line is progressively scanned, and the sensing line outputs the current signal in parallel.

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  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Amplifiers (AREA)

Abstract

本发明公开了一种信号处理及前置放大电路和触摸屏，信号处理及前置放大电路，用于触摸屏，包括：补偿电流产生单元，适于输出补偿电流信号，以消除触摸屏的像素点输出电流信号中的至少部分背景信号，背景信号为未被触摸时像素点输出电流信号；前置放大器，负相输入端适于接收像素点输出电流信号和补偿电流信号，正相输入端适于接收参考电压；反馈阻抗，适于连接前置放大器的负相输入端和输出端。采用本发明技术方案可以减小或去除像素点输出电流中的背景信号，使得前置放大器电路可以选用更小值的电容或电阻来获得较大的增益。采用本发明技术方案可以改变前置放大器电路的反馈阻抗（积分电容或电阻），从而调整增益，使其符合实际所需。

Description

信号处理及前置放大电路和触摸屏 本申请要求 2012 年 10 月 11 日提交中国专利局、 申请号为 201210385195.7、 发明名称为 "信号处理及前置放大电路和触摸屏" 的中国专利申请的优先权， 其全部内容通过引用结合在本申请中。 技术领域 本发明涉及电子技术领域，尤其涉及一种信号处理及前置放大电 路和触摸屏。 背景技术 电容式触摸屏（ Capacity Touch Panel, CTP )主要有自电容感应 式触摸屏和互电容感应式触摸屏两种。 互电容感应式触摸屏包括多条驱动线和多条感应线，驱动线和感 应线交叉放置， 在驱动线和感应线的交叉处形成互电容。 互电容感应 式触摸屏可以包括成阵列排布的互电容。 驱动线发出脉沖信号，感应线通过感应所述脉沖信号产生电流信 号。 互电容感应式触摸屏未被触摸时， 感应线输出稳定的背景信号， 所述背景信号经过电荷放大器电路后被转换为稳定的电荷信号，稳定 的电荷信号经过带通滤波器后被转换为稳定的输出电压。当人体接触 触摸屏时， 由于人体接地， 手指与触摸屏就形成一个等效电容， 驱动 线发出的脉沖信号可以通过这一等效电容流入地， 这样， 感应线产生 电流信号发生变化， 最终产生的输出电压也发生变化， 触摸操作被检 测出来。 由上述内容可知，互电容感应式触摸屏的感应线在触摸屏未被触 摸时产生背景信号， 触摸屏被触摸后， 感应线产生与所述背景信号叠 加在一起的电流信号。 在所述电流信号中， 相对于背景信号的电流变 化部分才是实际体现触摸信号的电流值。 电荷放大器电路实际上是积分电路的一种具体应用。电荷放大器 电路可以对接收到的电流信号进行积分处理， 产生相应的电荷信号。 电荷放大器电路的积分电容的电容值越小，输出电压越大，增益越大。 为了增大输出电压， 获得较大增益， 电荷放大器电路的积分电容 需要设置较小的电容值。 但是， 所述背景信号的电流值往往较大， 若 电荷放大器电路中的积分电容的电容值较小，则电荷放大器电路很容 易饱和。 电荷放大器电路饱和后， 无论触摸屏是否被触摸， 输出电压 不会发生变化， 触摸操作无法被检测出来。 发明内容 有鉴于此，本发明要解决的技术问题是现有电荷放大器电路无法 满足触摸屏检测所需。 为此， 本发明实施例采用如下技术方案： 一种信号处理及前置放大电路， 用于触摸屏， 包括： 补偿电流产生单元， 适于输出补偿电流信号， 以消除所述触摸屏 的像素点输出电流信号中的至少部分背景信号，所述背景信号为未被 触摸时像素点输出电流信号； 前置放大器， 负相输入端适于接收所述像素点输出电流信号和补 偿电流信号， 正相输入端适于接收参考电压； 反馈阻抗， 适于连接所述前置放大器的负相输入端和输出端。 可选的， 所述补偿电流产生单元包括： 存储单元， 适于存储所述触摸屏中所有像素点对应的背景信号； 电流输出单元，适于根据当前像素点的坐标从所述存储单元中查 找该像素点对应的背景信号，并根据查找到的背景信号产生补偿电流 信号； 电荷馈入阻抗，适于将所述补偿电流信号输出至所述前置放大器 的负相输入端。 可选的，所述电流输出单元适于根据当前像素点的坐标从存储单 元中的 LOOKUP TABLE中查找该像素点对应的背景信号。 可选的， 所述前置放大器为电荷放大器， 所述电荷馈入阻抗以及 反馈阻抗通过电容实现； 或者， 所述前置放大器为电压放大器或电流-电压转换器， 所述 电荷馈入阻抗以及反馈阻抗通过电阻实现。 可选的，所述存储单元存储所有像素点对应的背景信号的波形或 积分电荷量。 可选的，所述存储单元存储所有像素点对应的背景信号的实际波 形或实际波形的压缩形式。 可选的， 所述前置放大器为电荷放大器， 所述补偿电流信号与背 景信号同步且相位相反，所述补偿电流信号的积分电荷是所述背景信 号的积分电荷的 0.5-1.5倍。 可选的， 所述前置放大器为电压放大器或电流-电压变换器， 所 述补偿电流信号与背景信号同步且相位相反， 补偿电流信号 F2i与背 景信号 Fli满足：
Figure imgf000005_0001
, N为整数， 0·1 Μ 0·5。 可选的， 所述信号处理及前置放大电路还包括： 至少一路反馈支 路；所述至少一路反馈支路中的每一路反馈支路均设置于所述前置放 大器的负相输入端和输出端之间； 每一路所述反馈支路包括： 串接的开关和支路反馈阻抗。 一种信号处理及前置放大电路， 用于触摸屏， 包括： 前置放大器， 负相输入端适于接收所述触摸屏像素点输出电流信 号， 正相输入端适于接收参考电压； 反馈阻抗， 适于连接所述前置放大器的负相输入端和输出端； 至少一路反馈支路，其中每一路反馈支路均设置于所述前置放大 器的负相输入端和输出端之间， 所述每一路反馈支路包括： 串接的开 关和支路反馈阻抗。 可选的， 所述前置放大器为电荷放大器， 所述反馈阻抗以及支路 反馈阻抗通过电容实现； 或者， 所述前置放大器为电压放大器或电流-电压转换器， 所述 反馈阻抗以及支路反馈阻抗通过电阻实现。 可选的， 所述信号处理及前置放大电路还包括： 补偿电流产生单 元， 适于输出补偿电流信号， 以消除所述像素点输出电流信号中的至 少部分背景信号， 所述背景信号为未被触摸时像素点输出电流信号； 所述前置放大器的负相输入端还适于接收所述补偿电流信号。 可选的， 所述补偿电流产生单元包括： 存储单元， 适于存储所述触摸屏中所有像素点对应的背景信号； 电流输出单元，适于根据当前像素点的坐标从所述存储单元中查 找该像素点对应的背景信号，并根据查找到的背景信号产生补偿电流 信号； 电荷馈入阻抗，适于将所述补偿电流信号输出至所述前置放大器 的负相输入端。 可选的，所述电流输出单元适于根据当前像素点的坐标从存储单 元中的 LOOKUP TABLE中查找该像素点对应的背景信号。 可选的， 所述前置放大器为电荷放大器， 所述电荷馈入阻抗以及 反馈阻抗通过电容实现； 或者， 所述前置放大器为电压放大器或电流-电压转换器， 所述 电荷馈入阻抗以及反馈阻抗通过电阻实现。 可选的， 所述前置放大器为电荷放大器， 所述补偿电流信号与背 景信号同步且相位相反，所述补偿电流信号的积分电荷是所述背景信 号的积分电荷的 0.5-1.5倍。 可选的， 所述前置放大器为电压放大器或电流-电压变换器， 所 述补偿电流信号与背景信号同步且相位相反， 补偿电流信号 F2i与背 景信号 Fli满足：
Figure imgf000007_0001
, Ν为整数， 0.1 Μ 0.5。 一种触摸屏， 包括上述信号处理及前置放大电路。 可选的， 所述触摸屏包括多条驱动线和多条感应线， 所述信号处 理及前置放大电路与所述感应线电连接。 可选的， 所述驱动线和所述感应线位于不同层， 且二者之间通过 一绝缘层隔开。 可选的， 所述驱动线和所述感应线位于同一层。 可选的， 一根感应线对应连接一个所述信号处理及前置放大电 路。 可选的，所有感应线共同连接至一个所述信号处理及前置放大电 路。 与现有技术相比， 本发明技术方案存在以下优点： 采用本发明技术方案可以减小或去除像素点输出电流中的背景 信号，使得前置放大器电路可以选用更小值的电容或电阻来获得较大 的增益。 采用本发明技术方案可以改变前置放大器电路的反馈阻抗（积分 电容或电阻）， 从而调整增益， 使其符合实际所需。 附图说明 图 1 为本发明实施例一信号处理及前置放大电路的一结构示意 图； 图 2为本发明像素点输出电流信号的示意图； 图 3 为本发明实施例一信号处理及前置放大电路的另一结构示 意图； 图 4为本发明背景信号被存储时的示意图； 图 5 为本发明实施例一信号处理及前置放大电路的又一结构示 意图； 图 6为本发明像素点输出电流信号和补偿信号的一关系示意图； 图 7 为本发明像素点输出电流信号和补偿信号的另一关系示意 图； 图 8 为本发明实施例二信号处理及前置放大电路的一结构示意 图； 图 9 为本发明实施例二信号处理及前置放大电路的另一结构示 意图； 图 10为本发明实施例三信号处理及前置放大电路的一结构示意 图； 图 11为本发明实施例三信号处理及前置放大电路的另一结构示 意图; 图 12为本发明触摸屏的一结构示意图； 图 13为本发明触摸屏的另一结构示意图。 具体实施方式 下面结合附图对本发明的具体实施方式做详细的说明。在下列段 落中参照附图以举例方式更具体地描述本发明。根据下列说明， 本发 明的优点和特征将更清楚。 如图 1 所示， 本发明实施例一提供一种信号处理及前置放大电 路， 所述信号处理及前置放大电路用于触摸屏 5 , 包括： 补偿电流产 生单元 1 , 适于输出补偿电流信号 A2 , 以消除像素点输出电流信号 A1 中的至少部分背景信号， 所述背景信号为未触摸时触摸屏 5的像 素点输出电流信号； 前置放大器 3 , 负相输入端适于接收所述像素点 输出电流信号 A1 和补偿电流信号 A2 , 正相输入端适于接收参考电 压 VF (一般为接地端）； 反馈阻抗 4, 适于连接所述前置放大器 3的 负相输入端和输出端。 触摸屏 5可以为互电容感应式的触摸屏。互电容感应式触摸屏包 括多条驱动线和多条感应线， 驱动线和感应线交叉放置， 驱动线和感 应线的交叉处形成像素点， 即互电容。 具体的， 所以互电容感应式触 摸屏包括成阵列排布的互电容。 例如， 图 1中的触摸屏 5包括第一驱动线 52、 第二驱动线 53、 第一感应线 54和第二感应线 55。 第一驱动线 52和第一感应线 54的 交叉处形成第一像素点 524; 第一驱动线 52和第二感应线 55的交叉 处形成第二像素点 525; 第二驱动线 53和第一感应线 54的交叉处形 成第三像素点 534; 第二驱动线 53和第二感应线 55的交叉处形成第 四像素点 535; 所述第一像素点 524、 第二像素点 525、 第三像素点 534和第四像素点 535成阵列式排布。 图 2示出了未触摸和触摸时像素点输出电流信号之间的关系。从 图 2可以看出，触摸时像素点输出电流信号可以比未触摸时像素点输 出电流信号的幅值大，也可以比未触摸时像素点输出电流信号的幅值 小。 如图 3所示， 所述补偿电流产生单元 1可以包括： 存储单元 11 , 适于存储所述触摸屏中所有像素点对应的背景信号； 电流输出单元 12,适于根据当前像素点的坐标从所述存储单元中查找该像素点对应 的背景信号， 并才艮据查找到的背景信号产生补偿电流信号 A2; 电荷 馈入阻抗 2, 适于将所述补偿电流信号 A2输出至所述前置放大器的 负相输入端。 对于每一像素点， 存储单元 11存储了该像素点的坐标， 以及对 应的背景信号。 也就是说， 根据像素点的坐标可以查找出所述像素点 对应的背景信号，所述对应关系可以通过映射表 LOOKUP TABLE来 实现。 所述坐标可以根据所述像素点所在的驱动线和感应线来定义。 例如， 图 1中第一像素点 524所在的第一坐标为 （4, 2 ), 第二像素 点 525所在的第二坐标为 （5 , 2 ), 第三像素点 534所在的第三坐标 为 （4, 3 ), 第四像素点 535所在的第四坐标为 （5 , 3 )。 存储单元 11可以存储所有像素点对应的背景信号的波形或积分 电荷量。所述背景信号的波形为触摸屏 5未被触摸时的像素点输出电 流信号的波形。 所述波形可以为实际波形， 也可以为实际波形的压缩 形式。 具体压缩方法为本领域技术人员的公知常识， 此处不再赘述。 图 4示出了背景信号的实际波形、背景信号的积分电荷以及背景信号 的实际波形的压缩形式之间的关系。 其中， 所述背景信号的实际波形 和压缩形式的积分电荷应当相等。 继续参考图 3 , 电流输出单元 12可以根据当前像素点的坐标从 存储单元 11中的 LOOKUP TABLE中查找该像素点对应的背景信号。 具体的， 电流输出单元 12确定当前产生像素点输出电流信号的像素 点的坐标， 根据该像素点的坐标从存储单元 11 中查找该像素点对应 的背景信号， 并根据查找到的背景信号产生补偿电流信号。 电流输出 单元 12可以根据触摸屏驱动电路确定当前产生像素点输出电流信号 的像素点的坐标。如驱动电路设置的图 1所述的四个像素点的扫描顺 序分别为： 第一像素点 524和第二像素点 525 , 第三像素点 534和第 四像素点 535。 第一驱动线 52接收驱动信号后， 第一像素点 524通 过第一感应线 54向前置放大器 3的负相输入端输出电流信号； 第二 像素点 525通过第二感应线 55向前置放大器 3的负相输入端输出电 流信号。 第二驱动线 53接收驱动信号后， 第三像素点 534通过第一 感应线 54向前置放大器 3的负相输入端输出电流信号； 第四像素点 535通过第二感应线 55向前置放大器 3的负相输入端输出电流信号。 在当前向前置放大器 3 的负相输入端输出电流的像素点为第一像素 点 524时， 电流输出单元 12根据第一坐标为 （4, 2 )查找第一像素 点 524的背景信号。 如图 5所示， 所述前置放大器 3可以为电荷放大器 31。 前置放 大器 3为电荷放大器时， 电荷馈入阻抗 2通过电荷馈入电容 Cref 实 现， 反馈阻抗 4通过第一电容 Cfl实现。 前置放大器 3为电荷放大器 时， 所述补偿电流信号与背景信号同步且相位相反， 所述补偿电流信 号的积分电荷是所述背景信号的积分电荷的 0.5-1.5倍。 如图 6所示，假设触摸时像素点输出电流信号比未触摸时像素点 输出电流信号的幅值大，未触摸时像素点输出电流信号的积分电荷即 为背景信号的积分电荷。补偿电流产生单元 1可以产生第一补偿电流 信号， 所述第一补偿电流信号为一方波脉沖信号， 该方波脉沖信号与 未触摸时像素点输出电流信号同步且相位相反，该方波脉沖信号的积 分电荷是背景信号的积分电荷的 1-1.5倍， 在该条件下， 像素点输出 电流信号中的至少部分背景信号被消除，第一电容 Cfl可以选用电容 值较小的电容， 从而获得较大增益。 补偿电流产生单元 1也可以产生 第二补偿电流信号，所述第二补偿电流信号为所述背景信号的相位相 反信号， 两者同步且积分电荷相同， 在该条件下， 像素点输出电流信 号中的全部背景信号被消除，第一电容 Cfl同样可以选用电容值较小 的电容， 从而获得较大增益。 如图 7所示，假设触摸时像素点输出电流信号比未触摸时像素点 输出电流信号的幅值小，未触摸时像素点输出电流信号的积分电荷即 为背景信号的积分电荷。补偿电流产生单元 1可以产生第一补偿电流 信号， 所述第一补偿电流信号为一方波脉沖信号， 该方波脉沖信号与 未触摸时像素点输出电流信号同步且相位相反，该方波脉沖信号的积 分电荷是背景信号的积分电荷的 0.5-1倍， 在该条件下， 像素点输出 电流信号中的至少部分背景信号被消除，第一电容 Cfl可以选用电容 值较小的电容， 从而获得较大增益。 补偿电流产生单元 1也可以产生 第二补偿电流信号，所述第二补偿电流信号为所述背景信号的相位相 反信号， 两者同步且积分电荷相同， 在该条件下， 像素点输出电流信 号中的全部背景信号被消除，第一电容 Cfl同样可以选用电容值较小 的电容， 从而获得较大增益。 所述前置放大器 3还可以由电压放大器或电流 -电压转换器实现。 前置放大器 3为电流放大器时，电荷馈入阻抗 2和反馈阻抗 4通过电 阻实现， 补偿电流信号 F2i与背景信号 Fli同步且相位相反， 并满足 下面公式：
Figure imgf000012_0001
其中， N为整数， 0.1≤M≤0.5。 在满足上面所述的条件下，像素点输出电流信号中的至少部分背 景信号可以被消除。 如图 8 所示， 本发明实施例二提供一种信号处理及前置放大电 路， 所述信号处理及前置放大电路， 用于触摸屏 5, 包括： 前置放大器 3 , 负相输入端适于接收像素点输出电流信号， 正相 输入端适于接收参考电压 VF (一般为接地端）； 反馈阻抗 4,适于连接所述前置放大器 3的负相输入端和输出端； 至少一路反馈支路，其中每一路反馈支路 6均设置于所述前置放 大器 3的负相输入端和输出端之间， 所述每一路反馈支路包括： 串接 的开关 61和支路反馈阻抗 62。 实施例二所述的触摸屏可以为互电容感应式的触摸屏。关于电容 感应式的触摸屏的内容可以参照实施例一的描述， 此处不再赘述。 开关 61可以由 MOS晶体管实现， MOS晶体管导通和截止实现 开关 61的打开和闭合。 开关 61打开时， 前置放大器 3的负相输入端 通过反馈阻抗 4连接前置放大器 3的输出端； 开关 61闭合时， 支路 反馈阻抗 62和反馈阻抗 4并联， 前置放大器 3的负相输入端通过并 联的支路反馈阻抗 62和反馈阻抗 4连接前置放大器 3的输出端。 所 述开关 61的闭合和打开可以根据实际需要进行设置， 例如， 根据所 述触摸屏所需进行设置， 或者根据所述前置放大器 3 的状态进行设 置， 若前置放大器 3饱和时开关 61闭合。 此处以反馈支路为一个作示意性说明， 但可以理解的是， 所述反 馈支路的数量可以为一个、 两个、 三个或更多。 反馈支路中的支路反 馈阻抗 62可以相同， 也可以不同。 如图 9所示， 所述前置放大器 3 可以为电荷放大器 31 , 开关 61可以为第一 MOS晶体管 Sl。 前置放 大器 3为电荷放大器时，反馈阻抗 4通过第一电容 Cfl实现， 支路反 馈阻抗 62通过第二电容 CG实现。 第一 MOS晶体管 S1截止时， 前置放大器 3的负相输入端仅通 过第一电容 Cfl连接前置放大器 3的输出端， 该情况下， 电荷放大器 31和第一电容 Cfl组成第一电荷放大器电路。 第一 MOS晶体管 S1导通时， 第二电容 CG和第一电容 Cfl并 联，前置放大器 3的负相输入端通过并联的第二电容 CG和第一电容 Cfl连接前置放大器 3的输出端， 该情况下， 电荷放大器 31、 第一电 容 Cfl和第二电容 C£2组成第二电荷放大器电路。第二电荷放大器电 路的积分电容与第一电荷放大器电路的积分电容的电容值相比发生 变化。 通过变化的积分电容可以调整增益和信噪比， 使其满足实际的 设计所需。 如图 10所示， 本发明实施例三提供一种信号处理及前置放大电 路， 所述信号处理及前置放大电路用于触摸屏 5 , 包括： 补偿电流产 生单元 1、 前置放大器 3、 反馈阻抗 4以及至少一路反馈支路。 所述 至少一路反馈支路中的每一路反馈支路 6均设置于所述前置放大器 3 的负相输入端和前置放大器 3的输出端之间； 每一路所述反馈支路 6 包括： 串接的开关 61和支路反馈阻抗 62。 补偿电流产生单元 1、 前置放大器 3、 反馈阻抗 4和触摸屏 5的 具体描述可以参考实施例一，关于反馈支路 6的具体描述可以参考实 施例二， 此处不再赘述。 如图 11所示， 补偿电流产生单元 1包括： 存储单元 11 , 适于存 储所述触摸屏中所有像素点对应的背景信号； 电流输出单元 12, 适 于根据当前像素点的坐标从所述存储单元中查找该像素点对应的背 景信号， 并根据查找到的背景信号产生补偿电流信号； 电荷馈入阻抗 2, 适于将所述补偿电流信号输出至所述前置放大器的负相输入端。 所述前置放大器 3为电荷放大器 31 ,开关 61为第一 MOS晶体管 S1 , 电荷馈入阻抗 2、 反馈阻抗 4和支路反馈阻抗 62为电容。 当所述前置放大器为电压放大器或电流-电压转换器时， 电荷馈 入阻抗 2、 反馈阻抗 4和支路反馈阻抗 62为电阻。 需要说明的是， 以上所有实施例中， 前置放大电路的输出端还可 以串接一带通滤波器。 本发明技术方案还提供一种触摸屏，包括上述实施例所述的信号 处理及前置放大电路。 可选的， 所述触摸屏包括多条驱动线和多条感应线， 所述信号处 理及前置放大电路与所述感应线电连接。 具体的， 信号处理及前置放 大电路的前置放大器的负相输入端通过像素点的电流输出端与感应 线电连接。 可选的， 所述驱动线和所述感应线位于不同层， 且二者之间通过 一绝缘层隔开。 所述驱动线和所述感应线位于同一层。 可选的，所述信号处理及前置放大电路可以位于驱动线和感应线 所在的基板， 也可以所述基板之外。 可选的，所有感应线共同可以连接至一个所述信号处理及前置放 大电路， 如图 12所示。 其中， 每根感应线通过一个开关 51与信号处 理及前置放大电路相连接， 感应线输出电流信号时开关 51 闭合。 此 时， 所有像素点的扫描方式是： 驱动线逐行扫描， 感应线逐列输出电 流信号。 可选的 ,一根感应线可以对应连接一个所述信号处理及前置放大 电路， 如图 13所示。 此时， 所有像素点的扫描方式是： 驱动线逐行 扫描， 感应线并行输出电流信号。 以上所述仅是本发明的优选实施方式， 应当指出， 对于本技术领 域的普通技术人员来说， 在不脱离本发明原理的前提下， 还可以做出 若干改进和润饰， 这些改进和润饰也应视为本发明的保护范围。
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Claims

权 利 要 求
1. 一种信号处理及前置放大电路， 用于触摸屏， 其特征在于， 包括： 补偿电流产生单元， 适于输出补偿电流信号， 以消除所述触摸屏 的像素点输出电流信号中的至少部分背景信号，所述背景信号为未被 触摸时像素点输出电流信号； 前置放大器， 负相输入端适于接收所述像素点输出电流信号和补 偿电流信号， 正相输入端适于接收参考电压； 反馈阻抗， 适于连接所述前置放大器的负相输入端和输出端。
2. 如权利要求 1所述的信号处理及前置放大电路， 其特征在于， 所 述补偿电流产生单元包括： 存储单元， 适于存储所述触摸屏中所有像素点对应的背景信号； 电流输出单元，适于根据当前像素点的坐标从所述存储单元中查 找该像素点对应的背景信号，并根据查找到的背景信号产生补偿电流 信号； 电荷馈入阻抗，适于将所述补偿电流信号输出至所述前置放大器 的负相输入端。
3. 如权利要求 2所述的信号处理及前置放大电路， 其特征在于， 所 述电流输出单元适于根据当前像素点的坐标从存储单元中的 LOOKUP TABLE中查找该像素点对应的背景信号。
4. 如权利要求 2所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电荷放大器，所述电荷馈入阻抗以及反馈阻抗通过电 容实现； 或者， 所述前置放大器为电压放大器或电流-电压转换器， 所述 电荷馈入阻抗以及反馈阻抗通过电阻实现。
5. 如权利要求 2所述的信号处理及前置放大电路， 其特征在于， 所 述存储单元存储所有像素点对应的背景信号的波形或积分电荷量。
6. 如权利要求 5所述的信号处理及前置放大电路， 其特征在于， 所 述存储单元存储所有像素点对应的背景信号的实际波形或实际波形 的压缩形式。
7. 如权利要求 1所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电荷放大器，所述补偿电流信号与背景信号同步且相 位相反，所述补偿电流信号的积分电荷是所述背景信号的积分电荷的 0.5-1.5倍。
8. 如权利要求 1所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电压放大器或电流-电压变换器， 所述补偿电流信号 与背景信号同步且相位相反,补偿电流信号 F2i与背景信号 Fli满足:
Figure imgf000017_0001
, N为整数， 0·1 Μ 0·5。
9. 如权利要求 1所述的信号处理及前置放大电路， 其特征在于， 还 包括： 至少一路反馈支路； 所述至少一路反馈支路中的每一路反馈支 路均设置于所述前置放大器的负相输入端和输出端之间； 每一路所述反馈支路包括： 串接的开关和支路反馈阻抗。
10.—种信号处理及前置放大电路， 用于触摸屏， 其特征在于， 包括： 前置放大器， 负相输入端适于接收所述触摸屏像素点输出电流信号， 正相输入端适于接收参考电压； 反馈阻抗， 适于连接所述前置放大器的负相输入端和输出端； 至少一路反馈支路，其中每一路反馈支路均设置于所述前置放大 器的负相输入端和输出端之间， 所述每一路反馈支路包括： 串接的开 关和支路反馈阻抗。
11.如权利要求 10所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电荷放大器，所述反馈阻抗以及支路反馈阻抗通过电 容实现； 或者， 所述前置放大器为电压放大器或电流-电压转换器， 所述 反馈阻抗以及支路反馈阻抗通过电阻实现。
12.如权利要求 10所述的信号处理及前置放大电路， 其特征在于， 还 包括： 补偿电流产生单元， 适于输出补偿电流信号， 以消除所述像素 点输出电流信号中的至少部分背景信号，所述背景信号为未被触摸时 像素点输出电流信号； 所述前置放大器的负相输入端还适于接收所述补偿电流信号。
13.如权利要求 12所述的信号处理及前置放大电路， 其特征在于， 所 述补偿电流产生单元包括： 存储单元， 适于存储所述触摸屏中所有像素点对应的背景信号； 电流输出单元，适于根据当前像素点的坐标从所述存储单元中查 找该像素点对应的背景信号，并根据查找到的背景信号产生补偿电流 信号； 电荷馈入阻抗，适于将所述补偿电流信号输出至所述前置放大器 的负相输入端。
14.如权利要求 13所述的信号处理及前置放大电路， 其特征在于， 所 述电流输出单元适于根据当前像素点的坐标从存储单元中的 LOOKUP TABLE中查找该像素点对应的背景信号。
15.如权利要求 13所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电荷放大器，所述电荷馈入阻抗以及反馈阻抗通过电 容实现; 或者， 所述前置放大器为电压放大器或电流-电压转换器， 所述 电荷馈入阻抗以及反馈阻抗通过电阻实现。
16.如权利要求 12所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电荷放大器，所述补偿电流信号与背景信号同步且相 位相反，所述补偿电流信号的积分电荷是所述背景信号的积分电荷的 0.5-1.5倍。
17.如权利要求 11所述的信号处理及前置放大电路， 其特征在于， 所 述前置放大器为电压放大器或电流-电压变换器， 所述补偿电流信号 与背景信号同步且相位相反,补偿电流信号 F2i与背景信号 Fli满足:
Figure imgf000019_0001
Y 1 1 , N为整数， 0·1 Μ 0·5。
18.一种触摸屏， 其特征在于， 包括权利要求 1至 17任一项所述的信 号处理及前置放大电路。
19.如权利要求 18所述的触摸屏，所述触摸屏包括多条驱动线和多条 感应线， 所述信号处理及前置放大电路与所述感应线电连接。
20.如权利要求 19所述的触摸屏，所述驱动线和所述感应线位于不同 层， 且二者之间通过一绝缘层隔开。
21.如权利要求 19所述的触摸屏，所述驱动线和所述感应线位于同一 层。
22.如权利要求 19所述的触摸屏，一根感应线对应连接一个所述信号 处理及前置放大电路。
23.如权利要求 19所述的触摸屏，所有感应线共同连接至一个所述信 号处理及前置放大电路。
PCT/CN2013/073800 2012-10-11 2013-04-07 信号处理及前置放大电路和触摸屏 WO2014056313A1 (zh)

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