WO2024021516A1 - 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

Info

Publication number
WO2024021516A1
WO2024021516A1 PCT/CN2022/142932 CN2022142932W WO2024021516A1 WO 2024021516 A1 WO2024021516 A1 WO 2024021516A1 CN 2022142932 W CN2022142932 W CN 2022142932W WO 2024021516 A1 WO2024021516 A1 WO 2024021516A1
Authority
WO
WIPO (PCT)
Prior art keywords
capacitance
touch
detection circuit
signal
sensing electrode
Prior art date
Application number
PCT/CN2022/142932
Other languages
English (en)
French (fr)
Inventor
蒋宏
Original Assignee
深圳市汇顶科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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 CN202380011547.9A priority Critical patent/CN117693728A/zh
Publication of WO2024021516A1 publication Critical patent/WO2024021516A1/zh

Links

Images

Classifications

    • 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
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere

Definitions

  • Embodiments of the present application relate to the field of electronic circuit technology, and more specifically, to a capacitance detection circuit, a touch chip and an electronic device.
  • a touch screen usually includes a display layer and a touch layer.
  • the touch layer can use capacitive touch detection.
  • a detection electrode can be provided in the touch layer.
  • the touch screen detects The capacitance corresponding to the electrode will change. By detecting the change in the capacitance, the information that the finger is close to or touching the detection electrode can be obtained to determine the user's operation on the touch screen.
  • Embodiments of the present application provide a capacitance detection circuit, a touch chip and an electronic device, which can reduce the interference of the display layer in the touch screen on the capacitance detection in the touch layer and improve the capacitance detection accuracy and touch performance.
  • a capacitance detection circuit for detecting the capacitance to be measured between a sensing electrode and a driving electrode in a touch display device of an electronic device.
  • the capacitance detection circuit includes: a differential amplifier circuit, including: a first input terminal , the second input terminal and the output terminal; the first input terminal is connected to the sensing electrode and is used to receive the initial detection signal obtained by the sensing electrode based on the capacitance to be measured; the second input terminal is connected to the display cathode of the touch display device for Receive and display the noise interference signal coupled to the sensing electrode; the output terminal is used to output an effective detection signal based on the difference signal between the initial detection signal and the noise interference signal.
  • the effective detection signal is used to characterize the capacitance to be measured between the sensing electrode and the driving electrode.
  • the capacitance detection circuit also includes: a reference capacitor, the second input terminal is connected to the display cathode through the reference capacitor, wherein the capacitance value of the reference capacitor is equal to The capacitance value of the first coupling capacitor is related.
  • the setting of the reference capacitor can simulate the coupling between the display cathode and the sensing electrode, so that the noise interference signal received by the second input end of the differential amplifier circuit can be closer to or even equivalent to the coupling between the display cathode and the sensing electrode.
  • the actual noise of the sensing electrode interferes with the signal, thereby further improving the detection accuracy of the capacitance to be measured, thereby improving the touch detection performance of the touch display device.
  • the touch display device has N sensing electrodes; the capacitance detection circuit includes: N differential amplifier circuits, and the N first input terminals of the N differential amplifier circuits are connected to the N sensing electrodes in one-to-one correspondence. Electrode, where N is a positive integer greater than 1.
  • each sensing electrode can be configured with a differential amplifier circuit to process the detection signal induced by the sensing electrode, thereby ensuring that each sensing electrode detection performance of a sensing electrode.
  • the second input end of each of the N differential amplification circuits is connected to a reference capacitor, where the capacitance value of the reference capacitor is equal to the capacitance value of the first coupling capacitor.
  • each differential amplifier circuit the second input terminal is connected to the display cathode through a reference capacitor, and the second input terminal of each differential amplifier circuit can accurately simulate the coupling of the display cathode to each sensing electrode.
  • the actual noise interferes with the signal, thereby further ensuring the detection accuracy of each sensing electrode of the capacitance to be measured.
  • the N second input terminals of the N differential amplifier circuits are connected to the same reference capacitor, where the capacitance value of the reference capacitor is N times the capacitance value of the first coupling capacitor.
  • the N second input terminals of the N differential amplifier circuits can be commonly connected to the same reference capacitor, that is, the display cathode can provide display cathode noise to the N differential amplifier circuits through the same reference capacitor. Interference signal.
  • the overall circuit structure of the capacitance detection circuit is simpler, and the number of reference capacitors is smaller, which can greatly reduce the circuit complexity of the capacitance detection circuit and save the wiring space and manufacturing required for the capacitance detection circuit. cost.
  • the interference signal on the display cathode will be coupled to the driving voltage source or ground through the second coupling capacitor, but will not be coupled to the sensing electrode, causing interference to the detection signal on the sensing electrode, ensuring the capacitance detection circuit For the detection performance of the capacitor under test.
  • the driving electrode is suspended, and the capacitance value of the reference capacitor is also related to the capacitance value of the second coupling capacitor between the display cathode and the driving electrode and the capacitance value of the capacitance to be measured between the sensing electrode and the driving electrode. .
  • the interference signal on the display cathode can also be reduced or even eliminated through the second coupling capacitor and the capacitance to be measured.
  • the noise interference signal introduced by the sensing electrode ensures the detection performance of the capacitance detection circuit for the capacitance to be measured.
  • the differential amplifier circuit is disposed at the first input stage of the capacitance detection circuit.
  • the detection signal detected by the induction electrode is first received by the differential amplification circuit in the capacitance detection circuit. After being processed by the differential amplification circuit, it is then transmitted to the subsequent processing circuit to ensure the accuracy of subsequent signal processing. Reliability and accuracy.
  • the capacitance detection circuit further includes: a filter circuit, connected to the differential amplification circuit, for filtering the effective detection signal output by the differential amplification circuit.
  • the capacitance detection circuit further includes: an analog-to-digital conversion circuit, connected to the filter circuit, for converting the filtered effective detection signal into a digital signal.
  • the differential amplification circuit includes a fully differential amplifier.
  • the output range of the fully differential amplifier is doubled, and the signal obtained through the differential output has low distortion.
  • the fully differential amplifier operates faster, costs less, requires less space, and consumes less power. Therefore, in the embodiment of the present application, applying a fully differential amplifier to the capacitance detection circuit can further ensure the capacitance detection performance of the capacitance detection circuit and improve the capacitance detection accuracy.
  • a touch chip including: the capacitance detection circuit in the first aspect or any possible implementation of the first aspect.
  • an electronic device including: a touch display screen and the touch chip in the second aspect; wherein, the touch display screen is provided with sensing electrodes and driving electrodes for touch detection, and the touch chip is provided with To drive the driving electrode and detect the sensing electrode.
  • the touch display screen is a soft screen.
  • FIG. 1 is a schematic structural diagram of a touch display system provided by an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of the touch display device in FIG. 1 .
  • FIG. 3 is a schematic block diagram of a capacitance detection circuit provided by an embodiment of the present application.
  • FIG. 4 is another schematic block diagram of a capacitance detection circuit provided by an embodiment of the present application.
  • FIG. 5 is a schematic circuit diagram of the capacitance detection circuit provided by the embodiment of the present application.
  • FIG. 6 is another schematic circuit diagram of the capacitance detection circuit provided by the embodiment of the present application.
  • FIG. 7 is a schematic diagram of the coupling between the driving electrode, the sensing electrode and the capacitance detection circuit when the driving electrode is in two different states according to the embodiment of the present application.
  • FIG. 8 is another schematic circuit diagram of the capacitance detection circuit provided by the embodiment of the present application.
  • FIG. 9 is another schematic circuit diagram of the capacitance detection circuit provided by the embodiment of the present application.
  • FIG. 10 is another schematic circuit diagram of the capacitance detection circuit provided by an embodiment of the present application.
  • Figure 11 is a schematic connection diagram of a touch chip and a touch display screen provided by an embodiment of the present application.
  • the touch display system may include a touch display device and related driving devices and detection devices, such as a touch driving circuit, a touch detection circuit, etc.
  • the touch display device may include a touch layer and a display layer. Touch electrodes are formed in the touch layer, and the touch driving circuit is used to output a driving signal to drive the touch electrodes.
  • the touch detection circuit is used to detect the touch signal detected by the touch electrode.
  • the display layer can be a display, and the user can use a finger, an active pen, or other conductors to touch the icons or text on the display to perform corresponding touch operations. Examples of displays include, but are not limited to, Liquid Crystal Display (LCD), Organic Light Emitting Display (OLED), Plasma Display Panel (PDP), and Cathode Ray Tube (CRT) monitor etc.
  • LCD Liquid Crystal Display
  • OLED Organic Light Emitting Display
  • PDP Plasma Display Panel
  • CRT Cathode Ray Tube
  • FIG. 1 shows a schematic structural diagram of a touch display system 100 provided by an embodiment of the present application.
  • the touch display system 100 includes: a touch display device 110 and a touch control device 120 .
  • the touch control device 120 can be used to implement a touch driving function and a touch detection function.
  • the touch display device 110 may also be called a touch display screen or a touch display screen.
  • the touch control device 120 may be a touch chip.
  • the lowermost layer is the display layer 113, which may have a light-emitting unit.
  • the upper layer of the display layer 113 is the cathode plate 112, which is used to lead out the ground (GND) of the circuit in the light-emitting unit and also serves to isolate the touch layer 111 and the display layer 113.
  • the upper layer of the cathode plate 112 is the touch layer 111, and touch electrodes are formed in the touch layer 111.
  • the touch control device 120 can input driving signals to the touch electrodes in the touch layer 111, so that the touch Layer 111 implements mutual capacitance detection and/or self-capacitance detection.
  • the touch control device 120 can receive the sensing signal obtained by the touch layer 111 based on mutual capacitance detection and/or self-capacitance detection, and then implement the touch operation of the user's finger or stylus on the touch display device 110 .
  • the upper layer of the touch layer 111 that is, the top layer of the touch display device 110 may also be provided with a protective cover (not shown in FIG. 1 ).
  • the touch display system 100 may also include: a display control device 140 and a main control device 130 .
  • the display control device 140 is used to output a driving signal to the display layer 113 to drive the display layer 113 to display an image.
  • the main control device 130 is used to transmit control signals to the display control device 140 and the touch control device 120 to implement touch control and display control of the touch display system 100 .
  • the display control device 140 and the touch control device 120 are shown as two separate devices.
  • the display control device 140 and the touch control device 120 may be two separate control chips.
  • the display control device 140 and the touch control device 120 can also be integrated into the same device, for example, into the same control chip.
  • FIG. 2 shows a schematic structural diagram of the touch display device 110 in FIG. 1 .
  • a transmitting (TX) electrode and a receiving (RX) electrode are formed in the touch layer 111 .
  • the capacitance value of the coupling capacitor Cx to be measured will be affected.
  • the corresponding position information of the user's finger, active pen or other conductor on the touch layer 111 can be determined, thereby determining the user's operation on the touch display device 110 .
  • the touch control device 120 (not shown in Figure 2) sends the touch drive signal 121 to the TX electrode in the touch layer 111 for self-capacitance, mutual capacitance detection or active pen uplink coding
  • the RX electrode in the touch layer 111 can generate a sensing signal 122 based on the coupling capacitance Cx to be measured, or receive an active pen downlink coding signal based on the coupling capacitance Cx to be measured.
  • the touch control device 120 can based on the sensing signal 122 or The downlink coding signal is detected by the coupling capacitor Cx to be measured.
  • a coupling capacitor Cd is formed between the TX electrode and the cathode plate 112
  • a coupling capacitor Cs is formed between the RX electrode and the cathode plate 112 .
  • the display driving signal 123 will be coupled to the cathode plate 112 through the cache capacitor CD of the light-emitting unit 1131, forming a
  • the interference signal will affect the detection of the sensing signal 122 on the RX electrode through the coupling capacitor Cs, thereby affecting the detection of the coupling capacitor Cx to be measured, and even affect the touch detection performance of the touch display device 110 .
  • the present application provides the following capacitance detection circuit, which can reduce the impact of the interference signal on the cathode plate 112 on the detection of the coupling capacitance Cx to be measured in the touch layer 111, thereby reducing the touch detection of the touch display device 110. Functional impact.
  • FIG. 3 shows a schematic block diagram of a capacitance detection circuit 200 provided by an embodiment of the present application.
  • the capacitance detection circuit 200 can be used to detect the capacitance to be measured between the sensing electrode and the driving electrode in the touch display device of the electronic device.
  • the capacitance detection circuit 200 can be used to detect the capacitance Cx to be measured between the RX electrode (ie, the sensing electrode) and the TX electrode (ie, the driving electrode) in the above-mentioned touch display device 110 .
  • the capacitance detection circuit 200 includes a differential amplifier circuit 210 .
  • the differential amplifier circuit 210 includes: a first input terminal 211, a second input terminal 212 and an output terminal 213.
  • the first input terminal 211 is connected to the sensing electrode RX and is used for receiving the initial detection signal detected by the sensing electrode RX based on the capacitance Cx to be measured.
  • the second input terminal 212 is connected to the display cathode ELVSS of the touch display device, and is used for receiving the noise interference signal coupled from the display cathode ELVSS to the sensing electrode RX.
  • the output terminal 213 is used to output an effective detection signal based on the difference signal between the initial detection signal and the noise interference signal. The effective detection signal is used to characterize the capacitance to be measured Cx between the sensing electrode RX and the driving electrode TX.
  • a driving signal can be configured on the driving electrode TX.
  • the driving signal includes but is not limited to a square wave signal, a sinusoidal wave signal or a staircase wave signal, etc.
  • the driving signal can be coupled to the sensing electrode RX under the action of the capacitor Cx to be measured, so that the sensing electrode RX generates an initial detection signal induced by the driving signal, and the initial detection signal is related to the capacitance value of the capacitor Cx to be measured.
  • the cathode plate 112 of the touch display device 110 ie, the display cathode ELVSS in the embodiment of the present application
  • the interference signal brought by the display layer 113 is coupled.
  • the interference signal will be coupled to the sensing electrode RX through the first coupling capacitor Cs between the display cathode ELVSS and the sensing electrode RX, introducing a noise interference signal into the initial detection signal induced by the sensing electrode RX.
  • the initial detection signal generated on the sensing electrode RX is not only related to the capacitance value of the capacitor Cx to be measured, but also related to the noise interference signal introduced by the display cathode ELVSS.
  • the capacitance detection circuit 200 provided in the embodiment of the present application includes a differential amplifier circuit 210.
  • the first input terminal 211 of the differential amplifier circuit is used to receive the initial detection signal on the sensing electrode RX.
  • the second input terminal 211 of the differential amplifier circuit is used to receive the initial detection signal on the sensing electrode RX.
  • the input terminal 212 is used to receive the noise interference signal coupled from the display cathode ELVSS to the sensing electrode RX.
  • the output terminal 213 of the differential amplifier circuit is used to output an effective detection signal based on the difference signal between the initial detection signal and the noise interference signal.
  • the effective detection signal It will not be affected by the noise interference signal of the display cathode ELVSS, and can more reliably characterize the capacitance Cx to be measured between the sensing electrode RX and the driving electrode TX, thereby improving the detection accuracy of the capacitance Cx to be measured, and thereby improving the performance of the touch display device. Touch detection performance.
  • only one-stage differential amplification circuit 210 is needed in the capacitance detection circuit 200 to eliminate the noise interference signal coupled from the display cathode ELVSS to the sensing electrode RX, thereby realizing the connection between the sensing electrode RX and the sensing electrode RX in the touch display device.
  • This technical solution has fewer circuit stages and a simple circuit structure, so the overall power consumption is low. On this basis, this technical solution also has better capacitance detection accuracy, thereby achieving better touch detection performance to comprehensively guarantee touch control. Indicates the overall performance of the device.
  • FIG. 4 shows another schematic block diagram of the capacitance detection circuit 200 provided by the embodiment of the present application.
  • the capacitance detection circuit 200 further includes: a reference capacitor Cc, which is connected between the second input terminal 212 of the differential amplifier circuit 210 and the display cathode ELVSS.
  • the capacitance value of the reference capacitor Cc is related to the capacitance value of the first coupling capacitance Cs between the display cathode ELVSS and the sensing electrode RX.
  • the noise interference signal coupled from the display cathode ELVSS to the sensing electrode RX is related to the capacitance value of the first coupling capacitor Cs between the display cathode ELVSS and the sensing electrode RX.
  • the second input terminal 212 and the display cathode ELVSS can also be provided with a reference capacitor Cc, and the capacitance value of the reference capacitor Cc is coupled with the first The capacitance value of capacitor Cs is also relevant.
  • the setting of the reference capacitor Cc can simulate the coupling between the display cathode ELVSS and the sensing electrode RX, so that the noise interference signal received by the second input terminal 212 of the differential amplifier circuit 210 can be closer to or even equal to the coupling of the display cathode ELVSS.
  • the actual noise interference signal to the sensing electrode RX further improves the detection accuracy of the capacitance to be measured Cx, thereby improving the touch detection performance of the touch display device.
  • FIG. 5 and FIG. 6 show two schematic circuit diagrams of the capacitance detection circuit 200 provided by the embodiment of the present application.
  • the touch display device may have N detection channels, where N is a positive integer greater than 1.
  • Each detection channel may be provided with one sensing electrode RX, that is, the touch display device may have a total of N sensing electrodes RX, ranging from RX 1 to RX N.
  • the capacitance detection circuit 200 may include N differential amplification circuits 210, and the N first input terminals 211 of the N differential amplification circuits 210 are connected to the N sensing electrodes RX 1 to RX N in one-to-one correspondence.
  • the second input terminal 212 of each of the N differential amplification circuits 210 is connected to a reference capacitor Cc, where the capacitance value of the reference capacitor Cc is equal to It shows that the capacitance values of the first coupling capacitor Cs between the cathode ELVSS and the sensing electrode RX are equal.
  • each sensing electrode RX can be configured with a differential amplification circuit 210 corresponding to the detection signal sensed by the sensing electrode RX. processing to ensure the detection performance of each sensing electrode RX.
  • each differential amplifier circuit 210 the second input terminal 212 is connected to the display cathode ELVSS through a reference capacitor Cc, and the second input terminal 212 of each differential amplifier circuit 210 can accurately simulate the display cathode ELVSS coupled to each The actual noise interference signal of the sensing electrode RX further ensures the detection accuracy of each sensing electrode RX for the capacitance to be measured Cx.
  • the N second input terminals 212 of the N differential amplifier circuits 210 are connected to the same reference capacitor Cc, where the capacitance value of the reference capacitor Cc is the first N times the capacitance value of coupling capacitor Cs.
  • the reference capacitor Cc connected to the display cathode ELVSS can be regarded as a reference channel independent of the N detection channels.
  • the N second input terminals 212 of the N differential amplifier circuits 210 can be jointly connected to the same reference capacitor Cc, that is, the display cathode ELVSS can be connected to the N differential amplifier circuits through the same reference capacitor Cc.
  • 210 provides a noise interference signal showing the cathode ELVSS.
  • the overall circuit structure of the capacitance detection circuit 200 is simpler, and the number of reference capacitors is smaller, which can greatly reduce the circuit complexity of the capacitance detection circuit 200 and save the wiring required for the capacitance detection circuit 200 space and manufacturing costs.
  • the differential amplification circuit 210 can be a fully differential amplifier (Fully differential amplifiers, FDA).
  • the fully differential amplifier includes two output terminals 2131 and 2132. This results in a differential output mode of operation. Compared with traditional differential amplifiers, the output range of this fully differential amplifier is doubled, and the signal obtained through the differential output has low distortion. In addition, the fully differential amplifier operates faster, costs less, requires less space, and consumes less power. Therefore, in the embodiment of the present application, applying a fully differential amplifier to the capacitance detection circuit 200 can further ensure the capacitance detection performance of the capacitance detection circuit 200 and improve the capacitance detection accuracy.
  • the first input terminal 211 is used to input the V in- signal
  • the second input terminal 212 is used to input the V in+ signal
  • the first output terminal 2131 is used to input the V in- signal
  • the second output terminal 2132 is used to output the V out- signal.
  • a feedback resistor Rg is connected between the first output terminal 2131 and the first input terminal 211, and a feedback resistor Rg is also connected between the second output terminal 2132 and the second input terminal 212.
  • the resistance values of the two feedback resistors Rg are equal.
  • a differential input resistor (not shown in the figure) may also be connected between the first input terminal 211 and the sensing electrode RX, and a differential input resistor (not shown in the figure) may also be connected between the second input terminal 212 and the reference capacitor Cc. (not shown), the resistance values of the two differential input resistors are equal.
  • the gain a of this fully differential amplifier is the ratio of the feedback resistor Rg to the differential input resistance.
  • the differential amplifier circuit 210 in the embodiment of the present application can also be other types of differential amplifiers, aiming to convert the inputs of the first input terminal 211 and the second input terminal 212 into The signal only needs to be differentially amplified, and the specific type of the differential amplification circuit 210 is not limited in this application.
  • FIG. 7 shows a schematic coupling diagram of the driving electrode TX, the sensing electrode RX, and the capacitance detection circuit 200 when the driving electrode TX is in two different states.
  • the cathode ELVSS is coupled to the driving electrode TX through the second coupling capacitor Cd, and the driving electrode TX is coupled to the sensing electrode RX through the capacitor Cx to be measured.
  • the interference signal on the display cathode ELVSS will be coupled to the second coupling capacitor Cd and the capacitance to be measured Cx. Sensing electrode RX, thus causing interference and impact on the detection signal on the sensing electrode RX.
  • the driving electrode TX is connected to the driving voltage source VdrvM or the ground GND.
  • the interference signal on the display cathode ELVSS will be coupled to the driving voltage source VdrvM or the ground GND through the second coupling capacitor Cd, but will not be coupled to the sensing electrode RX, causing interference to the detection signal on the sensing electrode RX, ensuring The detection performance of the capacitance detection circuit 200 for the capacitance Cx to be measured.
  • the capacitance detection circuit 200 is connected to The capacitance value of the reference capacitor Cc at the second input end of the differential amplifier circuit 210 is not only related to the first coupling capacitance Cs between the display cathode ELVSS and the sensing electrode RX, but also related to the second coupling capacitance between the display cathode ELVSS and the driving electrode TX.
  • the capacitance to be measured is related to Cd and the capacitance to be measured Cx.
  • FIG. 8 and FIG. 9 show two other schematic circuit diagrams of the capacitance detection circuit 200 provided by embodiments of the present application.
  • N sensing electrodes RX can form N to-be-measured capacitances with the same driving electrode TX.
  • the capacitance value of the reference capacitor Cc connected to its second input terminal 212 can be the capacitance value of the first coupling capacitor Cs and the second series-connected capacitor Cs.
  • the capacitance value of the reference capacitor Cc connected to the second input terminal 212 of the N differential amplifier circuits 210 may be the first coupling capacitor Cs.
  • the capacitance value is N times the sum of the capacitance values of the series-connected second coupling capacitor Cd and the capacitance to be measured Cx.
  • the differential amplification circuit 210 may be disposed at the first input stage of the capacitance detection circuit 200 . That is, the detection signal detected by the sensing electrode RX is first received by the differential amplifier circuit 210 in the capacitance detection circuit 200. After being processed by the differential amplifier circuit 210, it is then transmitted to the subsequent processing circuit to ensure the reliability of subsequent signal processing. and accuracy.
  • FIG. 10 shows another schematic circuit diagram of the capacitance detection circuit 200 provided by the embodiment of the present application.
  • the capacitance detection circuit 200 may also include a filter circuit 220 connected to the differential amplification circuit 210 for filtering the effective detection signal output by the differential amplification circuit 210 .
  • the capacitance detection circuit 200 may also include an analog-to-digital conversion circuit 230 connected to the filter circuit 220 for converting the filtered effective detection signal into a digital signal.
  • the filter circuit 220 may be, for example, an analog anti-aliasing filter (AAF) with low-pass characteristics, which can prevent high-frequency signals or noise from being mixed into the analog-to-digital conversion circuit 230 .
  • AAF analog anti-aliasing filter
  • the analog-to-digital conversion circuit 230 may be, for example, an analog-to-digital converter (ADC), which is used to convert the effective detection signal into a digital signal.
  • ADC analog-to-digital converter
  • the digital signal facilitates subsequent data transmission and related signal processing.
  • the above-mentioned filter circuit 220 and analog-to-digital conversion circuit 230 can also be provided in any of the embodiments shown in Figures 5, 8 and 9. in the capacitance detection circuit 200.
  • the capacitance detection circuit 200 can also be provided with other types of signal processing circuits according to actual needs to improve the performance of capacitance detection and touch detection. Accuracy and reliability.
  • An embodiment of the present application also provides a touch chip, including the capacitance detection circuit in the various embodiments of the present application.
  • Figure 11 is a schematic connection diagram of a touch chip and a touch display screen provided by an embodiment of the present application.
  • the touch display screen includes a cathode layer 300 (ie, the cathode plate 112 shown in FIGS. 1 and 2 ), which is also the display cathode ELVSS in the above embodiments.
  • a touch electrode layer Above the cathode layer 300 is a touch electrode layer, which is used to sense the touch position of a finger or stylus and output a detection signal related to the capacitance value of the capacitor to be measured.
  • the touch electrode layer includes vertically distributed electrodes and horizontally distributed electrodes.
  • the vertical electrode 301 in FIG. 11 is a driving electrode TX
  • the horizontal electrode 302 is a detection electrode RX (also called a sensing electrode). It should be noted that in other embodiments, the vertical electrode 301 may also be a detection electrode RX, and the horizontal electrode 302 may be a driving electrode TX.
  • Drv1, Drv2, Drv3, and Drv4 are drive signals.
  • the drive signals can be signals applied to the drive electrodes by the drive circuit in the touch chip 303.
  • the drive electrodes and detection electrodes are both connected to the touch chip 303.
  • the detection electrode is used to input the detection signal to the capacitance detection circuit in the touch chip 303.
  • the detection signal can be Sens1, Sens2, Sens3, and Sens4 in Figure 11
  • the capacitance detection circuit may include a plurality of differential amplifier circuits, one of the input terminals of the plurality of differential amplifier circuits is used to receive the detection signals Sens1, Sens2, Sens3, and Sens4 respectively.
  • the cathode signal is formed on the cathode layer 300 as a reference signal for display driving in the display panel, when there is display driving, due to the impedance of the cathode layer 300, the cathode layer 300 will couple the interference signal of the display panel, and the interference signal will pass through the cathode layer
  • the coupling capacitance between 300 and the detection electrode is coupled into the detection channel where the detection electrode is located, resulting in an interference signal in the detection signal output by the detection electrode. This interference signal will seriously affect the accuracy of the capacitance detection circuit in calculating the finger touch position.
  • the cathode signal can be separately drawn from the edge of the cathode layer 300 through a lead 304 , and the cathode signal drawn out by the lead 304 is input into the touch chip 303 .
  • the aforementioned reference capacitor Cc is included to form a reference channel.
  • the cathode signal after passing through the reference capacitor Cc is input to another input end of multiple differential amplification circuits.
  • the capacitance detection circuit can accurately calculate the touch position of the finger or stylus on the touch display screen based on the detection signals output by the multiple differential amplification circuits. .
  • An embodiment of the present application also provides an electronic device.
  • the electronic device includes: a touch display screen; and the touch chip in the various embodiments of the present application.
  • the touch display screen is provided with a sensing electrode RX and a driving electrode TX for touch detection, and the touch chip is used to drive the driving electrode TX and detect the sensing electrode RX.
  • the touch display screen can be the touch display device in any of the above embodiments.
  • the touch display screen can be a hard screen or a soft screen.
  • the base material for preparing the display screen is either a hard material or a soft material.
  • the base material of the hard screen may be glass, and the base material of the soft screen may be polyimide (PI), etc.
  • the touch display screen is a soft screen
  • the thickness of each stack in the display screen becomes thinner. Therefore, the distance between the display cathode ELVSS and the touch layer in the touch display screen becomes smaller.
  • the display cathode ELVSS The coupling with the touch layer becomes larger. Therefore, the display cathode ELVSS in the soft screen has a greater impact on the capacitance detection in the touch layer.
  • 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 gaming device, a vehicle-mounted electronic device or a wearable smart device, and Electronic databases, cars, bank automated teller machines (Automated Teller Machine, ATM) and other electronic equipment.
  • the wearable smart devices include full-featured and large-sized devices that can realize complete or partial functions without relying on smartphones, such as smart watches or smart glasses, and those that only focus on a certain type of application function and need to cooperate with other devices such as smartphones. Use, such as various types of smart bracelets, smart jewelry and other equipment for physical sign monitoring.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Input By Displaying (AREA)

Abstract

一种电容检测电路、触控芯片和电子设备。电容检测电路（200）用于检测电子设备的触控显示装置（110）中的感应电极（RX）与驱动电极（TX）之间的待测电容（Cx），电容检测电路（200）包括：差分放大电路（210），其具有第一输入端（211）、第二输入端（212）和输出端（213）；第一输入端（211）连接于感应电极（RX），用于接收感应电极（RX）基于待测电容（Cx）检测得到的初始检测信号；第二输入端（212）连接于触控显示装置的显示阴极（ELVSS，112），用于接收显示阴极（ELVSS，112）耦合至感应电极（RX）的噪声干扰信号；输出端（213）用于基于初始检测信号与噪声干扰信号的差值信号输出有效检测信号，有效检测信号用于表征感应电极（RX）与驱动电极（TX）之间的待测电容（Cx）。该技术方案能够降低触控屏中显示层（113）对触控层（111）中电容检测的干扰，提高电容检测准确度和触控性能。

Description

电容检测电路、触控芯片和电子设备
本申请要求2022年7月28日提交中国专利局、申请号为202210899472.X、发明名称为“电容检测电路、芯片及电子设备”的中国发明申请的优先权，其全部内容通过应用结合在本申请中。
技术领域
本申请实施例涉及电子电路技术领域，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
随着智能手机和平板的发展，目前的显示屏一般都具有触控功能，该类型的显示屏也可称之为触控屏或者触摸屏。触控屏通常包括显示层与触控层，其中，触控层可采用电容式触控检测，该触控层中可设置有检测电极，当有导体例如手指，靠近或触摸检测电极时，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，从而判断用户在触控屏上的操作。
随着触控屏厚度的降低，该显示层与触控层之间的耦合越来越大，不仅加大了触控检测对屏幕显示的干扰，也加大了屏幕显示对触控检测的干扰，影响触控检测性能。鉴于此，如何降低触控屏中显示层对触控层中电容检测的干扰，是一项亟待解决的技术问题。
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，能够降低触控屏中显示层对触控层中电容检测的干扰，提高电容检测准确度和触控性能。
第一方面，提供一种电容检测电路，用于检测电子设备的触控显示装置中的感应电极与驱动电极之间的待测电容，电容检测电路包括：差分放大电路，包括：第一输入端、第二输入端和输出端；第一输入端连接于感应电极，用于接收感应电极基于待测电容检测得到的初始检测信号；第二输入端连接于触控显示装置的显示阴极，用于接收显示阴极耦合至感应电极的噪声干扰 信号；输出端用于基于初始检测信号与噪声干扰信号的差值信号输出有效检测信号，有效检测信号用于表征感应电极与驱动电极之间的待测电容。
通过本申请实施例的技术方案，电容检测电路中仅需要一级差分放大电路，即可消除显示阴极耦合至感应电极的噪声干扰信号，实现对触控显示装置中感应电极与驱动电极之间的待测电容的可靠检测。该技术方案电路级数少、电路结构简单因而整体功耗较低，在此基础上，该技术方案还具有较佳的电容检测精度，从而实现较佳的触控检测性能，以综合保障触控显示装置的整体性能。
在一些可能的实施方式中，显示阴极和感应电极之间具有第一耦合电容；电容检测电路还包括：参考电容，第二输入端通过参考电容连接于显示阴极，其中，参考电容的电容值与第一耦合电容的电容值相关。
通过该实施方式的技术方案，参考电容的设置可以模拟显示阴极与感应电极之间的耦合，使得该差分放大电路的第二输入端接收的噪声干扰信号能够更为接近乃至等同于显示阴极耦合至感应电极的实际噪声干扰信号，从而进一步提高待测电容的检测精度，进而提高触控显示装置的触控检测性能。
在一些可能的实施方式中，触控显示装置具有N个感应电极；电容检测电路包括：N个差分放大电路，N个差分放大电路的N个第一输入端一一对应的连接于N个感应电极，其中，N为大于1的正整数。
通过该实施方式的技术方案，在触控显示装置具有N个感应电极的情况下，每个感应电极可对应配置一个差分放大电路，用于对该感应电极感应的检测信号进行处理，从而保障每个感应电极的检测性能。
在一些可能的实施方式中，N个差分放大电路中每个差分放大电路的第二输入端连接一个参考电容，其中，参考电容的电容值与第一耦合电容的电容值相等。
通过该实施方式的技术方案，在每个差分放大电路中，第二输入端通过一个参考电容连接于显示阴极，每个差分放大电路的第二输入端可准确模拟显示阴极耦合至每个感应电极的实际噪声干扰信号，从而进一步保障每个感应电极对待测电容的检测准确性。
在一些可能的实施方式中，N个差分放大电路的N个第二输入端连接同一个参考电容，其中，参考电容的电容值为第一耦合电容的电容值的N倍。
通过该实施方式的技术方案，N个差分放大电路的N个第二输入端可以 共同连接于同一个参考电容，即显示阴极可通过该同一个参考电容向N个差分放大电路提供显示阴极的噪声干扰信号。该实施方式下，电容检测电路整体的电路结构更为简单，且参考电容的数量较少，能够较大程度的降低电容检测电路的电路复杂度，节省电容检测电路所需的走线空间以及制造成本。
在一些可能的实施方式中，显示阴极和驱动电极之间具有第二耦合电容；驱动电极连接于驱动电压源或地，以使得显示阴极的干扰信号不会通过第二耦合电容耦合至感应电极。
通过该实施方式的技术方案，显示阴极上的干扰信号会通过第二耦合电容耦合至驱动电压源或地，而不会耦合至感应电极，对感应电极上的检测信号造成干扰，保障电容检测电路对于待测电容的检测性能。
在一些可能的实施方式中，驱动电极悬空，参考电容的电容值还与显示阴极和驱动电极之间的第二耦合电容的电容值以及感应电极与驱动电极之间的待测电容的电容值相关。
通过该实施方式的技术方案，在驱动电极TX处于悬空状态的情况下，通过对参考电容的电容值的相关设置，也能够降低乃至消除显示阴极上的干扰信号通过第二耦合电容以及待测电容对感应电极引入的噪声干扰信号，保障电容检测电路对于待测电容的检测性能。
在一些可能的实施方式中，差分放大电路设置于电容检测电路的第一个输入级。
通过该实施方式的技术方案，感应电极检测得到的检测信号首先被电容检测电路中的差分放大电路接收，经过该差分放大电路的处理后，再传输给后续的处理电路，以保障后续信号处理的可靠性和准确性。
在一些可能的实施方式中，电容检测电路还包括：滤波电路，与差分放大电路相连，用于对差分放大电路输出的有效检测信号进行滤波处理。
在一些可能的实施方式中，电容检测电路还包括：模数转换电路，与滤波电路相连，用于将滤波后的有效检测信号转换为数字信号。
在一些可能的实施方式中，差分放大电路包括全差分放大器。
通过该实施方式的技术方案，相比于传统的差分放大器，全差分放大器的输出范围扩展了一倍，且通过差分输出得到的信号失真度较低。除此之外，该全差分放大器的运行速度更快，成本更低，所需空间更小，且功耗更低。因而，在本申请实施例中，将全差分放大器应用于电容检测电路中，可以进 一步保障该电容检测电路的电容检测性能，提高电容检测精度。
第二方面，提供一种触控芯片，包括：第一方面或第一方面中任一可能的实施方式中的电容检测电路。
第三方面，提供一种电子设备，包括：触控显示屏以及第二方面中的触控芯片；其中，触控显示屏中设置有用于触控检测的感应电极与驱动电极，触控芯片用于驱动驱动电极并检测感应电极。
在一些可能的实施方式中，触控显示屏为软屏。
附图说明
图1是本申请实施例提供的一种触控显示系统的示意性结构图。
图2是图1中触控显示装置的一种示意性结构图。
图3是本申请实施例提供的电容检测电路的一种示意性框图。
图4是本申请实施例提供的电容检测电路的另一示意性框图。
图5是本申请实施例提供的电容检测电路的一种示意性电路图。
图6是本申请实施例提供的电容检测电路的另一示意性电路图。
图7是本申请实施例提供的驱动电极处于两种不同状态时，该驱动电极与感应电极以及电容检测电路的耦合示意图。
图8是本申请实施例提供的电容检测电路的另一示意性电路图。
图9是本申请实施例提供的电容检测电路的另一示意性电路图。
图10是本申请实施例提供的电容检测电路的另一示意性电路图。
图11为本申请实施例提供的一种触控芯片与触摸显示屏的示意性连接图。
具体实施方式
下面将结合附图，对本申请实施例中的技术方案进行描述。
本申请涉及触控显示系统。该触控显示系统可包括触控显示装置以及相关驱动装置和检测装置，例如触控驱动电路、触控检测电路等。触控显示装置可以包括触控层和显示层，触控层中形成有触控电极，触控驱动电路用于输出驱动信号以对该触控电极进行驱动。触控检测电路用于检测该触控电极检测到的触控信号。显示层可以为显示器，用户可以利用手指、主动笔、或其他导体触碰显示器上的图符或文字实现相应的触控操作。显示器的示例包 括但不限于液晶显示器(Liquid Crystal Display，LCD)，有机发光显示器(Organic Light Emitting Display，OLED)，等离子体显示器(Plasma Display Panel，PDP)以及阴极射线管(Cathode Ray Tube，CRT)显示器等等。
图1示出了本申请实施例提供的一种触控显示系统100的示意性结构图。
如图1所示，该触控显示系统100包括：触控显示装置110和触控控制装置120，该触控控制装置120可用于实现触控驱动功能以及触控检测功能。可选地，在本申请中，触控显示装置110也可以称之为触控显示屏或者触摸显示屏。在一些实施例中，该触控控制装置120可以为触控芯片。
在该触控显示装置110中，最下层为显示层113，其中可具有发光单元。显示层113的上一层为阴极板112，用于将发光单元中电路的地(GND)引出去，同时起来隔离触控层111和显示层113的作用。阴极板112的上一层为触控层111，该触控层111中形成有触控电极，触控控制装置120可向该触控层111中的触控电极输入驱动信号，以使得触控层111实现互电容检测和/或自电容检测。然后，触控控制装置120可接收触控层111基于互电容检测和/或自电容检测得到的感应信号，进而实现用户手指或者触控笔在该触控显示装置110上的触控操作。该触控层111的上层，即触控显示装置110的最顶层还可设置有起保护作用的盖板(图1中未示出)。
除了触控显示装置110和触控控制装置120以外，如图1所示，触控显示系统100还可包括：显示控制装置140和主控装置130。其中，显示控制装置140用于向显示层113输出驱动信号以驱动显示层113显示图像。主控装置130用于向显示控制装置140和触控控制装置120传输控制信号，以实现触控显示系统100的触控控制以及显示控制。
可以理解的是，图1中作为示例，将显示控制装置140和触控控制装置120示为了两个分立装置，例如，该显示控制装置140和触控控制装置120可以为分立的两个控制芯片。在一些替代实施方式中，该显示控制装置140和触控控制装置120也可以集成为同一个装置，例如，可以集成为同一个控制芯片。
图2示出了图1中触控显示装置110的一种示意性结构图。
如图2所示，触控层111中形成有发射(TX)电极和接收(RX)电极。TX电极与RX电极之间具有待测耦合电容Cx。当用户手指、主动笔或者其 它导体靠近于该待测耦合电容Cx时，会影响该待测耦合电容Cx的电容值。通过对该待测耦合电容Cx进行检测，可以确定用户手指、主动笔或者其它导体在触控层111对应的位置信息，从而判断用户在触控显示装置110上的操作。
具体地，当触控控制装置120(图2中未示出)向触控层111中的TX电极发送触控驱动信号121进行自容、互容检测或者主动笔上行(Uplink)打码时，触控层111中的RX电极可基于待测耦合电容Cx产生感应信号122，或者基于待测耦合电容Cx接收主动笔下行(Downlink)打码信号，触控控制装置120可基于该感应信号122或者下行打码信号对待测耦合电容Cx进行检测。
另外，如图2所示，在触控层111中，TX电极与阴极板112之间形成有耦合电容Cd，RX电极与阴极板112之间形成有耦合电容Cs。当显示控制装置140(图2中未示出)向显示层113发送显示驱动信号123以进行图像显示时，该显示驱动信号123会通过发光单元1131的缓存电容C D耦合至阴极板112，形成干扰信号，该干扰信号会通过耦合电容Cs影响RX电极上感应信号122的检测，进而影响待测耦合电容Cx的检测，乃至影响触控显示装置110的触控检测性能。
鉴于此，本申请提供如下一种电容检测电路，能够降低上述阴极板112上的干扰信号对触控层111中待测耦合电容Cx检测的影响，从而降低对触控显示装置110的触控检测功能的影响。
图3示出了本申请实施例提供的一种电容检测电路200的示意性框图。该电容检测电路200可用于检测电子设备的触控显示装置中的感应电极与驱动电极之间的待测电容。例如，该电容检测电路200可用于检测上述触控显示装置110中RX电极(即感应电极)与TX电极(即驱动电极)之间的待测电容Cx。
如图3所示，该电容检测电路200包括：差分放大电路210。该差分放大电路210包括：第一输入端211、第二输入端212和输出端213。
其中，第一输入端211连接于感应电极RX，用于接收该感应电极RX基于待测电容Cx检测得到的初始检测信号。第二输入端212连接于触控显示装置的显示阴极ELVSS，用于接收该显示阴极ELVSS耦合至感应电极RX的噪声干扰信号。输出端213用于基于初始检测信号与噪声干扰信号的差值 信号输出有效检测信号，该有效检测信号用于表征感应电极RX与驱动电极TX之间的待测电容Cx。
具体地，在本申请实施例中，感应电极RX和驱动电极TX之间具有待测电容Cx，在执行待测电容Cx的检测从而执行触控检测功能时，驱动电极TX上可配置有驱动信号，该驱动信号包括但不限于是方波信号、弦波信号或者阶梯波信号等等。该驱动信号可在待测电容Cx的作用下，耦合至感应电极RX，以使得感应电极RX产生感应于驱动信号的初始检测信号，该初始检测信号与待测电容Cx的电容值相关。
如前文图2所示实施例所述，若触控显示装置110的显示层113处于显示状态，则该触控显示装置110的阴极板112(即本申请实施例中的显示阴极ELVSS)上会耦合有显示层113带来的干扰信号。如图3所示，该干扰信号会通过显示阴极ELVSS与感应电极RX之间的第一耦合电容Cs耦合至感应电极RX，在感应电极RX感应产生的初始检测信号中引入噪声干扰信号。
因此，在本申请实施例中，感应电极RX上产生的初始检测信号不仅与待测电容Cx的电容值相关，而且与显示阴极ELVSS引入的噪声干扰信号相关。
鉴于此，本申请实施例提供的电容检测电路200中，包括差分放大电路210，该差分放大电路的第一输入端211用于接收感应电极RX上的初始检测信号，该差分放大电路的第二输入端212用于接收显示阴极ELVSS耦合至感应电极RX的噪声干扰信号，该差分放大电路的输出端213用于根据初始检测信号与噪声干扰信号的差值信号输出有效检测信号，该有效检测信号不会受到显示阴极ELVSS的噪声干扰信号的影响，可较为可靠的表征感应电极RX与驱动电极TX之间的待测电容Cx，从而提高待测电容Cx的检测精度，进而提高触控显示装置的触控检测性能。
通过本申请实施例的技术方案，电容检测电路200中仅需要一级差分放大电路210，即可消除显示阴极ELVSS耦合至感应电极RX的噪声干扰信号，实现对触控显示装置中感应电极RX与驱动电极TX之间的待测电容Cx的可靠检测。该技术方案电路级数少、电路结构简单因而整体功耗较低，在此基础上，该技术方案还具有较佳的电容检测精度，从而实现较佳的触控检测性能，以综合保障触控显示装置的整体性能。
图4示出了本申请实施例提供的电容检测电路200的另一示意性框图。
如图4所示，在本申请实施例中，电容检测电路200还包括：参考电容Cc，连接于差分放大电路210的第二输入端212与显示阴极ELVSS之间。该参考电容Cc的电容值与显示阴极ELVSS和感应电极RX之间的第一耦合电容Cs的电容值相关。
具体地，显示阴极ELVSS耦合至感应电极RX的噪声干扰信号与显示阴极ELVSS和感应电极RX之间的第一耦合电容Cs的电容值相关。为了能够准确的向差分放大电路210的第二输入端212输入该噪声干扰信号，第二输入端212与显示阴极ELVSS也可设置有参考电容Cc，且该参考电容Cc的电容值与第一耦合电容Cs的电容值也相关。
因此，该参考电容Cc的设置可以模拟显示阴极ELVSS与感应电极RX之间的耦合，使得该差分放大电路210的第二输入端212接收的噪声干扰信号能够更为接近乃至等同于显示阴极ELVSS耦合至感应电极RX的实际噪声干扰信号，从而进一步提高待测电容Cx的检测精度，进而提高触控显示装置的触控检测性能。
在图4所示实施例的基础上，图5和图6示出了本申请实施例提供的电容检测电路200的两种示意性电路图。
如图5和图6所示，触控显示装置可具有N个检测通道，其中，N为大于1的正整数。每个检测通道可设置有一个感应电极RX，即触控显示装置可具有RX 1至RX N共N个感应电极RX。在该情况下，电容检测电路200可包括N个差分放大电路210，该N个差分放大电路210的N个第一输入端211一一对应的连接于N个感应电极RX 1至RX N。
可选地，在一些实施方式中，如图5所示，N个差分放大电路210中每个差分放大电路210的第二输入端212连接一个参考电容Cc，其中，参考电容Cc的电容值与显示阴极ELVSS和感应电极RX之间的第一耦合电容Cs的电容值相等。
通过本申请实施例的技术方案，在触控显示装置具有N个感应电极RX的情况下，每个感应电极RX可对应配置一个差分放大电路210，用于对该感应电极RX感应的检测信号进行处理，从而保障每个感应电极RX的检测性能。
进一步地，在每个差分放大电路210中，第二输入端212通过一个参考电容Cc连接于显示阴极ELVSS，每个差分放大电路210的第二输入端212 可准确模拟显示阴极ELVSS耦合至每个感应电极RX的实际噪声干扰信号，从而进一步保障每个感应电极RX对待测电容Cx的检测准确性。
可选地，在另一些实施方式中，如图6所示，N个差分放大电路210的N个第二输入端212连接同一个参考电容Cc，其中，该参考电容Cc的电容值为第一耦合电容Cs的电容值的N倍。
具体地，在该实施方式中，相比于具有N个感应电极RX的N个检测通道，该连接于显示阴极ELVSS的参考电容Cc可看成是独立于N个检测通道的参考通道。
通过该实施方式的技术方案，N个差分放大电路210的N个第二输入端212可以共同连接于同一个参考电容Cc，即显示阴极ELVSS可通过该同一个参考电容Cc向N个差分放大电路210提供显示阴极ELVSS的噪声干扰信号。该实施方式下，电容检测电路200整体的电路结构更为简单，且参考电容的数量较少，能够较大程度的降低电容检测电路200的电路复杂度，节省电容检测电路200所需的走线空间以及制造成本。
可选地，作为示例，在上述图5和图6所示实施例中，差分放大电路210可以为全差分放大器(Fully differential amplifiers，FDA)，该全差分放大器包括两个输出端2131和2132，从而形成差分输出的操作方式。相比于传统的差分放大器，该全差分放大器的输出范围扩展了一倍，且通过差分输出得到的信号失真度较低。除此之外，该全差分放大器的运行速度更快，成本更低，所需空间更小，且功耗更低。因而，在本申请实施例中，将全差分放大器应用于电容检测电路200中，可以进一步保障该电容检测电路200的电容检测性能，提高电容检测精度。
具体地，如图5和图6所示，在该全差分放大器中，第一输入端211用于输入V in-信号，第二输入端212用于输入V in+信号，第一输出端2131用于输出V out+信号，第二输出端2132用于输出V out-信号，V out+信号与V out-信号之差即为该全差分放大器的输出信号，(V out+-V out-)＝a*(V in+-V in-)，其中，a为该全差分放大器的增益。
继续参见图5和图6所示，第一输出端2131与第一输入端211之间连接有反馈电阻Rg，且第二输出端2132与第二输入端212之间也连接有反馈电阻Rg，该两个反馈电阻Rg的电阻值相等。另外，第一输入端211与感测电极RX之间还可连接有差分输入电阻(图中未示出)，第二输入端212与 参考电容Cc之间也可连接有差分输入电阻(图中未示出)，该两个差分输入电阻的电阻值相等。该全差分放大器的增益a为反馈电阻Rg与差分输入电阻的比值。
可以理解的是，本申请实施例中的差分放大电路210除了可以为上述全差分放大器以外，还可以为其它类型的差分放大器，旨在能将第一输入端211和第二输入端212的输入信号进行差分放大即可，本申请对该差分放大电路210的具体类型不做限定。
可选地，在触控显示装置中，驱动电极的不同状态可能会影响本申请实施例中感应电极的运行状态。图7示出了驱动电极TX处于两种不同状态时，该驱动电极TX与感应电极RX以及电容检测电路200的耦合示意图。
如图7中的(a)图和(b)图所示，显示阴极ELVSS通过第二耦合电容Cd耦合于驱动电极TX，而驱动电极TX通过待测电容Cx耦合于感应电极RX。
在一些实施方式中，如图7中的(a)图所示，在驱动电极TX处于悬空状态的情况下，显示阴极ELVSS上的干扰信号会通过第二耦合电容Cd以及待测电容Cx耦合至感应电极RX，因而对感应电极RX上的检测信号造成干扰和影响。
在另一些实施方式中，如图7中的(b)图所示，驱动电极TX连接于驱动电压源VdrvM或地GND。在该情况下，显示阴极ELVSS上的干扰信号会通过第二耦合电容Cd耦合至驱动电压源VdrvM或地GND，而不会耦合至感应电极RX，对感应电极RX上的检测信号造成干扰，保障电容检测电路200对于待测电容Cx的检测性能。
在驱动电极TX处于悬空状态的情况下，为了降低乃至消除显示阴极ELVSS上的干扰信号通过第二耦合电容Cd以及待测电容Cx对感应电极RX引入的噪声干扰信号，电容检测电路200中连接于差分放大电路210第二输入端的参考电容Cc的电容值除了与显示阴极ELVSS与感应电极RX之间的第一耦合电容Cs相关以外，还与显示阴极ELVSS与驱动电极TX之间的第二耦合电容Cd以及待测电容Cx之间的待测电容相关。
可选地，图8和图9示出了本申请实施例提供的电容检测电路200的另两种示意性电路图。在图8和图9所示实施例中，N个感应电极RX可以与同一个驱动电极TX形成N个待测电容。
如图8所示，在每个感应电极RX对应的一个差分放大电路210中，与其第二输入端212连接的参考电容Cc的电容值可以为第一耦合电容Cs的电容值与串联的第二耦合电容Cd和待测电容Cx的电容值之和。具体地，Cc的电容值可通过如下公式计算得到：Cc＝Cs+(Cd*Cx)/(Cd+Cx)。
如图9所示，在N个感应电极RX对应的N个差分放大电路210中，与N个差分放大电路210的第二输入端212连接的参考电容Cc的电容值可以为第一耦合电容Cs的电容值与串联的第二耦合电容Cd和待测电容Cx的电容值之和的N倍。具体地，Cc的电容值可通过如下公式计算得到：Cc＝N*(Cs+(Cd*Cx)/(Cd+Cx))。
可选地，在一些实施方式中，差分放大电路210可设置于电容检测电路200的第一个输入级。即，感应电极RX检测得到的检测信号首先被电容检测电路200中的差分放大电路210接收，经过该差分放大电路210的处理后，再传输给后续的处理电路，以保障后续信号处理的可靠性和准确性。
在上文图6所示实施例的基础上，图10示出了本申请实施例提供的电容检测电路200的另一示意性电路图。
如图10所示，在本申请实施例中，电容检测电路200还可包括：滤波电路220，与差分放大电路210相连，用于对差分放大电路210输出的有效检测信号进行滤波处理。
可选地，如图10所示，电容检测电路200还可包括：模数转换电路230，与滤波电路220相连，用于将滤波后的有效检测信号转换为数字信号。
其中，该滤波电路220例如可以是具有低通特性的模拟抗混叠滤波器(Analog Antialiasing Filter，AAF)，可以避免高频信号或噪声混叠到模数转换电路230中。
模数转换电路230例如可以是模数转换器(Analog-to-Digital Converter，ADC)，用于将有效检测信号转换为数字信号，该数字信号便于后续的数据传输和相关信号处理。
可以理解的是，上述滤波电路220和模数转换电路230除了可设置于图6所示实施例的电容检测电路200中，还可以设置于图5、图8和图9任一所示实施例的电容检测电路200中。
另外，该电容检测电路200除了可以包括上述差分放大电路210、滤波电路220和模数转换电路230以外，还可以根据实际需求设置其它类型的信 号处理电路，以便于提高电容检测以及触控检测的准确性和可靠性。
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。
图11为本申请实施例提供的一种触控芯片与触摸显示屏的示意性连接图。
如图11所示，触摸显示屏包括阴极层300(即图1和图2中所示的阴极板112)，该阴极层300也为上文各实施例中的显示阴极ELVSS。阴极层300之上为触摸电极层，该触摸电极层用于感测手指或触控笔的触摸位置并输出与待测电容的电容值相关的检测信号。触摸电极层包括了纵向分布的电极和横向分布的电极，以图11中的纵向电极301为驱动电极TX，横向电极302为检测电极RX(也称感应电极)进行示意。需要说明的是，在另一些实施方式中，纵向电极301也可以为检测电极RX，横向电极302可以为驱动电极TX。
图11中Drv1、Drv2、Drv3、Drv4为驱动信号，该驱动信号可为触控芯片303中的驱动电路施加在驱动电极上的信号，驱动电极和检测电极均与触控芯片303连接，在手指或触控笔靠近或者接触触摸显示屏的上表面时，检测电极用于将检测信号输入到触控芯片303中的电容检测电路，该检测信号可为图11中的Sens1、Sens2、Sens3、Sens4，电容检测电路可包括多个差分放大电路，该多个差分放大电路的其中一个输入端用于分别接收该检测信号Sens1、Sens2、Sens3、Sens4。
由于阴极层300上形成有阴极信号作为显示面板中显示驱动的参考信号，在有显示驱动时，由于阴极层300存在阻抗，阴极层300会耦合显示面板的干扰信号，该干扰信号会通过阴极层300与检测电极之间的耦合电容耦合进检测电极所在的检测通道，从而导致检测电极输出的检测信号中存在干扰信号，该干扰信号会严重影响电容检测电路计算手指触摸位置的准确性。
本申请实施例中，如图11所示，可将阴极信号通过一根引线304从阴极层300的边缘单独引出，该引线304引出的阴极信号输入至触控芯片303中，触控芯片303中包含了前述的参考电容Cc，以形成参考通道。经过参考电容Cc后的阴极信号分别输入至多个差分放大电路的另一个输入端，电容检测电路可根据多个差分放大电路输出的检测信号准确计算手指或触控笔在触摸显示屏上的触摸位置。
本申请实施例还提供了一种电子设备，该电子设备包括：触控显示屏；以及，上述本申请各种实施例中的触控芯片。其中，触控显示屏中设置有用于触控检测的感应电极RX与驱动电极TX，触控芯片用于驱动该驱动电极TX并检测感应电极RX。
可选地，该触控显示屏可以为上文任意实施例中的触控显示装置。
可选地，该触控显示屏可以为硬屏或者软屏。其中，硬屏和软屏的区别在于，制备显示屏的基底材料为硬质材料或者为软质材料。作为示例，硬屏的基底材料可以为玻璃等，软屏的基底材料可以为聚酰亚胺(Polyimide，PI)等。
在触控显示屏为软屏的情况下，显示屏中各叠层的厚度变得更薄，因而，触控显示屏中显示阴极ELVSS与触控层之间的距离变小，该显示阴极ELVSS与触控层之间的耦合变大。因而，软屏中显示阴极ELVSS对于触控层中的电容检测的影响更大。通过本申请实施例的技术方案，可以良好的解决软屏中显示阴极ELVSS对触控检测影响，综合提升电子设备的触控检测性能。
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。
为便于说明，在本申请的各实施例中，相同的附图标记表示相同的部件，并且为了简洁，在不同实施例中，省略对相同部件的详细说明。
除非另有说明，本申请实施例所使用的所有技术和科学术语与本申请的技术领域的技术人员通常理解的含义相同。本申请中所使用的术语只是为了描述具体的实施例的目的，不是旨在限制本申请的范围。本申请所使用的术语“和/或”包括一个或多个相关的所列项的任意的和所有的组合。
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 (14)

  1. 一种电容检测电路，其特征在于，用于检测电子设备的触控显示装置中的感应电极与驱动电极之间的待测电容，所述电容检测电路包括：
    差分放大电路，包括：第一输入端、第二输入端和输出端；
    所述第一输入端连接于所述感应电极，用于接收所述感应电极基于所述待测电容检测得到的初始检测信号；
    所述第二输入端连接于所述触控显示装置的显示阴极，用于接收所述显示阴极耦合至所述感应电极的噪声干扰信号；
    所述输出端用于基于所述初始检测信号与所述噪声干扰信号的差值信号输出有效检测信号，所述有效检测信号用于表征所述感应电极与所述驱动电极之间的待测电容。
  2. 根据权利要求1所述的电容检测电路，其特征在于，所述显示阴极和所述感应电极之间具有第一耦合电容；
    所述电容检测电路还包括：参考电容，所述第二输入端通过所述参考电容连接于所述显示阴极，其中，所述参考电容的电容值与所述第一耦合电容的电容值相关。
  3. 根据权利要求2所述的电容检测电路，其特征在于，所述触控显示装置具有N个所述感应电极；
    所述电容检测电路包括：N个所述差分放大电路，N个所述差分放大电路的N个第一输入端一一对应的连接于N个所述感应电极，其中，N为大于1的正整数。
  4. 根据权利要求3所述的电容检测电路，其特征在于，N个所述差分放大电路中每个所述差分放大电路的第二输入端连接一个所述参考电容，其中，所述参考电容的电容值与所述第一耦合电容的电容值相等。
  5. 根据权利要求3所述的电容检测电路，其特征在于，N个所述差分放大电路的N个第二输入端连接同一个所述参考电容，其中，所述参考电容的电容值为所述第一耦合电容的电容值的N倍。
  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，所述显示阴极和所述驱动电极之间具有第二耦合电容；
    所述驱动电极连接于驱动电压源或地，以使得所述显示阴极的干扰信号不会通过所述第二耦合电容耦合至所述感应电极。
  7. 根据权利要求2至5中任一项所述的电容检测电路，其特征在于，所述驱动电极悬空，所述参考电容的电容值还与所述显示阴极和所述驱动电极之间的第二耦合电容的电容值以及所述感应电极与所述驱动电极之间的待测电容的电容值相关。
  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，所述差分放大电路设置于所述电容检测电路的第一个输入级。
  9. 根据权利要求8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，与所述差分放大电路相连，用于对所述差分放大电路输出的有效检测信号进行滤波处理。
  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：
    模数转换电路，与所述滤波电路相连，用于将滤波后的所述有效检测信号转换为数字信号。
  11. 根据权利要求1至10中任一项所述的电容检测电路，其特征在于，所述差分放大电路包括全差分放大器。
  12. 一种触控芯片，其特征在于，包括：根据权利要求1至11中任一项所述的电容检测电路。
  13. 一种电子设备，其特征在于，包括：触控显示屏以及根据权利要求12所述的触控芯片；
    其中，所述触控显示屏中设置有用于触控检测的感应电极与驱动电极，所述触控芯片用于驱动所述驱动电极并检测所述感应电极。
  14. 根据权利要求13所述的电子设备，其特征在于，所述触控显示屏为软屏。
PCT/CN2022/142932 2022-07-28 2022-12-28 电容检测电路、触控芯片和电子设备 WO2024021516A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202380011547.9A CN117693728A (zh) 2022-12-28 2023-10-20 电容检测电路、触摸显示装置和电子设备

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202210899472.X 2022-07-28
CN202210899472.XA CN115128358A (zh) 2022-07-28 2022-07-28 电容检测电路、芯片及电子设备

Publications (1)

Publication Number Publication Date
WO2024021516A1 true WO2024021516A1 (zh) 2024-02-01

Family

ID=83386863

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/142932 WO2024021516A1 (zh) 2022-07-28 2022-12-28 电容检测电路、触控芯片和电子设备

Country Status (2)

Country Link
CN (1) CN115128358A (zh)
WO (1) WO2024021516A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115128358A (zh) * 2022-07-28 2022-09-30 深圳市汇顶科技股份有限公司 电容检测电路、芯片及电子设备

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102193698A (zh) * 2010-03-02 2011-09-21 株式会社日立显示器 坐标输入装置和具有该坐标输入装置的显示装置
US20180329573A1 (en) * 2017-05-12 2018-11-15 Synaptics Incorporated Active feedforward interference cancellation techniques for sensor analog front-end
US20190042029A1 (en) * 2015-03-26 2019-02-07 Pixart Imaging Inc. Control chip for touch panel with high sensitivity and operating method thereof
US20190220143A1 (en) * 2018-01-18 2019-07-18 Samsung Display Co., Ltd. Display device
CN110096181A (zh) * 2018-01-31 2019-08-06 三星显示有限公司 显示设备
US20200103993A1 (en) * 2018-09-28 2020-04-02 Apple Inc. Common mode noise mitigation for integrated touch screens
CN111902801A (zh) * 2020-01-22 2020-11-06 深圳市汇顶科技股份有限公司 电容检测电路、触控芯片和电子设备
CN112947791A (zh) * 2021-03-12 2021-06-11 深圳市汇顶科技股份有限公司 用于触控屏中多个通道触控检测的方法和装置
CN115128358A (zh) * 2022-07-28 2022-09-30 深圳市汇顶科技股份有限公司 电容检测电路、芯片及电子设备
CN217931820U (zh) * 2022-07-28 2022-11-29 深圳市汇顶科技股份有限公司 电容检测电路、芯片及电子设备

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102193698A (zh) * 2010-03-02 2011-09-21 株式会社日立显示器 坐标输入装置和具有该坐标输入装置的显示装置
US20190042029A1 (en) * 2015-03-26 2019-02-07 Pixart Imaging Inc. Control chip for touch panel with high sensitivity and operating method thereof
US20180329573A1 (en) * 2017-05-12 2018-11-15 Synaptics Incorporated Active feedforward interference cancellation techniques for sensor analog front-end
US20190220143A1 (en) * 2018-01-18 2019-07-18 Samsung Display Co., Ltd. Display device
CN110096181A (zh) * 2018-01-31 2019-08-06 三星显示有限公司 显示设备
US20200103993A1 (en) * 2018-09-28 2020-04-02 Apple Inc. Common mode noise mitigation for integrated touch screens
CN111902801A (zh) * 2020-01-22 2020-11-06 深圳市汇顶科技股份有限公司 电容检测电路、触控芯片和电子设备
CN112947791A (zh) * 2021-03-12 2021-06-11 深圳市汇顶科技股份有限公司 用于触控屏中多个通道触控检测的方法和装置
CN115128358A (zh) * 2022-07-28 2022-09-30 深圳市汇顶科技股份有限公司 电容检测电路、芯片及电子设备
CN217931820U (zh) * 2022-07-28 2022-11-29 深圳市汇顶科技股份有限公司 电容检测电路、芯片及电子设备

Also Published As

Publication number Publication date
CN115128358A (zh) 2022-09-30

Similar Documents

Publication Publication Date Title
US10282026B2 (en) Measuring body capacitance effect in touch sensitive device
US10185443B2 (en) Touch sensing error compensation
US9477356B2 (en) System and method to drive touch panel to measure hover
US10261628B2 (en) Driving chip, circuit film, chip-on-film type driving circuit, and display device having built-in touchscreen
US9377907B2 (en) Self capacitance implementation method
US9280245B2 (en) Touch panel sensor having dual-mode capacitive sensing for detecting an object
US6661408B2 (en) Touch screen capable of isolating noise signals
KR20170081128A (ko) 능동형 스타일러스 펜과 그를 포함한 터치 센싱 시스템, 및 그 구동방법
WO2024021516A1 (zh) 电容检测电路、触控芯片和电子设备
WO2021147007A1 (zh) 电容检测电路、触控芯片和电子设备
TWM557388U (zh) 具有壓力感測的觸控顯示系統
US11360617B2 (en) Touch substrate and touch screen
WO2018209766A1 (zh) 一种触控显示面板
CN110244882A (zh) 减轻来自传感器电极的电磁辐射
TW202311924A (zh) 觸摸屏干擾檢測方法、觸控芯片以及電子設備
US11275468B2 (en) Capacitance detection circuit, touch control chip and electronic device
WO2021128209A1 (zh) 电容检测电路、触控芯片和电子设备
US20210255727A1 (en) Sensor diagnostics for in-cell touch screen controllers
WO2021243532A1 (zh) 电容检测电路、触控芯片和电子设备
US20220083757A1 (en) Fingerprint sensing apparatus
CN205281452U (zh) 一种集成触控显示面板和集成触控显示装置
KR20120124230A (ko) 터치감지기 및 그 구동 방법과 그를 이용한 디스플레이장치
TWI531844B (zh) 電容式觸控面板及其驅動方法
KR20120036619A (ko) 터치스크린 컨트롤러 아이씨
US20190042055A1 (en) Touch display driving circuit

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22952945

Country of ref document: EP

Kind code of ref document: A1