Touch circuit, touch display screen and touch chip

Abstract

The embodiment of the invention provides a touch circuit, a touch display screen and a touch chip. The touch circuit comprises a touch detection circuit and a touch array, the touch array comprises touch signal lines which are arranged in a crossed manner; the touch detection circuit includes: a first amplification circuit coupled to two touch signal lines; the first amplifying circuit is used for outputting a first voltage signal and a second voltage signal respectively based on the inductive capacitors coupled with the two touch signal lines; a second amplification circuit coupled to the first amplification circuit; the second amplifying circuit is used for performing differential operation on the first voltage signal and the second voltage signal and determining the position where the touch operation occurs according to a differential operation result.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of integrated circuits, and in particular to a touch control circuit, a touch control display screen, and a touch control chip. Background Art

[0002] Touch screens are easy to use and simple to operate, and have become one of the core components of smart electronic devices. Capacitive touch screens are currently the mainstream technology for touch screens due to their support for multi-touch, mature technology, and low manufacturing costs. Capacitive touch screens can convert touch actions into electrical signals based on the capacitance formed by objects such as the user's hand or a stylus and the electrodes of the capacitive touch screen. Therefore, how to reduce the impact of noise on capacitive touch to improve the accuracy of touch detection has become an urgent problem to be solved in the industry. Summary of the invention

[0003] In view of this, embodiments of the present application provide a touch circuit, a touch display screen, and a touch chip.

[0004] On the one hand, an embodiment of the present application provides a touch circuit, comprising: a touch detection circuit and a touch array; the touch array comprises touch signal lines arranged crosswise;

[0005] The touch detection circuit comprises:

[0006] A first amplifier circuit is coupled to the two touch signal lines; the first amplifier circuit is used to output a first voltage signal and a second voltage signal respectively based on the inductive capacitance coupled to the two touch signal lines;

[0007] The second amplifier circuit is coupled to the first amplifier circuit; the second amplifier circuit is used for performing a differential operation on the first voltage signal and the second voltage signal, and determining a position where a touch operation occurs according to a differential operation result.

[0008] In some embodiments, the first amplifying circuit includes an input common-mode amplifier; the input common-mode amplifier is used to isolate noise coupled to the second amplifying circuit through the touch signal line.

[0009] In some embodiments, the input common-mode amplifier is further configured to receive an excitation signal, and output the first voltage signal and the second voltage signal based on the excitation signal and the sensing capacitance coupled between the two touch signal lines.

[0010] In some embodiments, the input common-mode amplifier includes a first input terminal and a second input terminal respectively coupled to the two touch signal lines, and a first output terminal and a second output terminal coupled to the second amplification circuit; the first input terminal and the first output terminal are connected through a first wire; the second input terminal and the second output terminal are connected through a second wire.

[0011] In some embodiments, the second amplification circuit includes a differential amplifier;

[0012] The differential amplifier comprises a third input terminal, a fourth input terminal, a third output terminal and a fourth output terminal; the third input terminal is used to receive the first voltage signal, and the fourth input terminal is used to receive the second voltage signal;

[0013] The second amplifying circuit further includes:

[0014] A first capacitor coupled between the third input terminal and the third output terminal;

[0015] The second capacitor is coupled between the fourth input terminal and the fourth output terminal; the first capacitor and the second capacitor are used as operational feedback capacitors for the differential operation.

[0016] In some embodiments, the second amplification circuit further includes:

[0017] a first variable resistor connected in parallel with the first capacitor between the third input terminal and the third output terminal; when the amount of charge stored in the first capacitor is greater than a first threshold, the first capacitor is discharged through the first variable resistor;

[0018] A second variable resistor is connected in parallel with the second capacitor between the fourth input terminal and the fourth output terminal; when the amount of charge stored in the second capacitor is greater than a second threshold, the second capacitor is discharged through the second variable resistor.

[0019] On the other hand, an embodiment of the present application further provides a touch display screen, comprising: a pixel array and a touch circuit coupled to each other;

[0020] The touch control circuit comprises: a touch control detection circuit and a touch control array located on the pixel array; the touch control array comprises touch control signal lines arranged crosswise;

[0021] The touch detection circuit comprises:

[0022] A first amplifier circuit is coupled to the two touch signal lines; the first amplifier circuit is used to output a first voltage signal and a second voltage signal respectively based on the inductive capacitance coupled to the two touch signal lines;

[0023] The second amplifier circuit is coupled to the first amplifier circuit; the second amplifier circuit is used for performing a differential operation on the first voltage signal and the second voltage signal, and determining a position where a touch operation occurs according to a differential operation result.

[0024] In some embodiments, the first amplifying circuit includes an input common-mode amplifier; the input common-mode amplifier is used to isolate noise coupled to the second amplifying circuit through the touch signal line.

[0025] In some embodiments, the input common-mode amplifier is further configured to receive an excitation signal, and output the first voltage signal and the second voltage signal based on the excitation signal and the sensing capacitance coupled between the two touch signal lines.

[0026] In some embodiments, the input common-mode amplifier includes a first input terminal and a second input terminal respectively coupled to the two touch signal lines, and a first output terminal and a second output terminal coupled to the second amplification circuit; the first input terminal and the first output terminal are connected through a first wire; the second input terminal and the second output terminal are connected through a second wire.

[0027] In some embodiments, the second amplification circuit includes a differential amplifier;

[0028] The differential amplifier comprises a third input terminal, a fourth input terminal, a third output terminal and a fourth output terminal; the third input terminal is used to receive the first voltage signal, and the fourth input terminal is used to receive the second voltage signal;

[0029] The second amplifying circuit further includes:

[0030] A first capacitor coupled between the third input terminal and the third output terminal;

[0031] The second capacitor is coupled between the fourth input terminal and the fourth output terminal; the first capacitor and the second capacitor are used as operational feedback capacitors for the differential operation.

[0032] In some embodiments, the second amplification circuit further includes:

[0033] a first variable resistor connected in parallel with the first capacitor between the third input terminal and the third output terminal; when the amount of charge stored in the first capacitor is greater than a first threshold, the first capacitor is discharged through the first variable resistor;

[0034] A second variable resistor is connected in parallel with the second capacitor between the fourth input terminal and the fourth output terminal; when the amount of charge stored in the second capacitor is greater than a second threshold, the second capacitor is discharged through the second variable resistor.

[0035] On the other hand, an embodiment of the present application further provides a touch control chip, including: the touch control circuit according to any one of the above embodiments.

[0036] In the embodiment of the present application, the first amplifier circuit is used to output the first voltage signal and the second voltage signal respectively based on the inductive capacitance coupled by the two touch signal lines, and the second amplifier circuit is used to perform a differential operation on the first voltage signal and the second voltage signal, and determine the position where the touch operation occurs according to the differential operation result. In this way, the touch circuit performs a differential operation on the signals output by the two touch signal lines on the basis of completing the touch detection, thereby reducing the influence of display noise and improving the accuracy of touch detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of a touch control circuit provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of self-capacitance and mutual capacitance in a touch control circuit provided in an embodiment of the present application;

[0039] Figure 3 A schematic diagram of a touch detection circuit provided in an embodiment of the present application;

[0040] Figure 4 A schematic diagram of another touch control circuit provided in an embodiment of the present application;

[0041] Figure 5 A schematic diagram of a touch detection circuit in another touch circuit provided in an embodiment of the present application;

[0042] Figure 6 A schematic diagram of another touch circuit for mutual capacitance detection provided in an embodiment of the present application;

[0043] Figure 7 A schematic diagram of another touch circuit performing self-capacitance detection provided by an embodiment of the present application;

[0044] Figure 8 A schematic diagram of a touch display screen provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The following will combine the implementation methods of this application and the accompanying drawings to clearly and completely describe the technical solutions in the implementation methods of this application. Obviously, the described implementation methods are only part of the implementation methods of this application, not all of the implementation methods. Based on the implementation methods in this application, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features known in the art are not described; that is, all features of the actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0047] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0048] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0049] At present, flexible displays have become a major trend for the next generation of displays due to their convertibility, storability and novelty. It is already a general trend to make thinner and more transparent screens and touch sensors, such as Organic Light-Emitting Diode (OLED) technology. At the same time, the touch sensor film is directly deposited on the display or used in combination with a polarizer, such as On-Cell Touch technology, so a more accurate touch detection method is the general trend. Screen touch technology usually uses the detection of the change in transcapacitance to determine whether a touch occurs, which includes mutual capacitance detection and self-capacitance detection.

[0050] like Figure 1 A touch control circuit 100 is shown, including a touch detection circuit 110 and a touch control array 120. The touch control array 120 includes a plurality of touch input signal lines L1 and a plurality of touch output signal lines L2 arranged crosswise. Exemplarily, the plurality of touch input signal lines L1 are respectively connected to the transmitting terminals TX0 to TXN, and the plurality of touch output signal lines L2 are respectively connected to the receiving terminals RX0 to RXN, where N is a positive integer. It should be noted that the number of transmitting terminals TX and receiving terminals RX may also be different, that is, the number of touch input signal lines L1 and the number of touch output signal lines L2 are different.

[0051] In mutual capacitance detection, the transmitter TX can be used to load signals of various waveforms, while the receiver RX is connected to the touch detection circuit 110 to perform touch detection operations. The touch detection circuit 110 can be an analog front end circuit (AnalogFront End, AFE). For a single touch unit, the mutual capacitance Cm is formed between the touch input signal line L1 and the touch output signal line L2, which is a parasitic capacitance between the two signal lines, and its size is usually less than 1pF.

[0052] like Figure 2 As shown, the self-capacitance Ctx is formed between the touch input signal line L1 and the display panel common electrode (DisplayCathode) 130, and the self-capacitance Crx is formed between the touch output signal line L2 and the display panel common electrode 130. The self-capacitance Ctx and the self-capacitance Crx are usually about 10pF. It can be understood that in the self-capacitance detection, each touch input signal line L1 and touch output signal line L2 will be connected to the touch detection circuit ( Figure 1 Only the touch output signal line L2 connected to the touch detection circuit is shown in the figure, and the transmitting end TX and the receiving end RX can be used to load signals of various waveforms. Since the touch array 120 is located above the pixel array of the display screen 101, the display noise will be coupled to the touch array 120 through the capacitance Csg between the display screen 101 and the common electrode 130, thereby affecting the touch detection of self-capacitance and mutual capacitance.

[0053] In some embodiments, when a touch operation occurs, the change in mutual capacitance is about 10%, that is, Cm×10%. During self-capacitance detection, the capacitive load of each signal line is the self-capacitance of a single detection unit multiplied by N, that is, Ctx×N or Crx×N, and the change in self-capacitance is Ctx×10% or Crx×10%. Therefore, for the touch detection circuit, the focus is on how to identify the change of smaller mutual capacitance Cm, how to drive a larger self-capacitance load and increase the detection amount, and how to eliminate the influence of display noise on touch detection.

[0054] like Figure 3The figure shows a schematic diagram of a touch detection circuit 110, including an amplifier 111. The amplifier 111 has a first input terminal Vim and a second input terminal Vip, the first input terminal Vim is coupled to the touch signal line, and the second input terminal Vip is used to input an excitation signal Vex. The output terminal Vout of the amplifier 111 is coupled to the first input terminal Vim through a wire and a buffer capacitor Cbuffer. The touch detection circuit 110 performs touch detection by charging and discharging electric charges. Here, the self-capacitance Ctx detection is taken as an example for explanation. The excitation signal Vex can be a periodically changing square wave AC signal. The high level of the excitation signal Vex is VH, and the low level is VL. The output signal of the touch detection circuit 110 is a square wave AC signal with the same frequency and phase as the excitation signal Vex, and its high level is Vout_H=VH×(Ctx / Cbuffer), and the low level is Vout_L=VL*×(Ctx / Cbuffer). That is to say, the amplitude of the output signal is related to the size of the self-capacitance Ctx and the buffer capacitance Cbuffer. Since the self-capacitance Ctx sensed by the touch detection circuit 110 is about 700pF, if you want to correctly identify the change of 1pF, Cbuffer needs to be close to the size of the self-capacitance Ctx to prevent the high level Vout_H from exceeding the range. This makes the buffer capacitance Cbuffer very large, which is not conducive to circuit design.

[0055] like Figure 4 As shown, the embodiment of the present application provides a touch circuit 200, including: a touch detection circuit 210 and a touch array 220; the touch array 220 includes touch signal lines arranged crosswise; the touch detection circuit 210 includes: a first amplifier circuit 211, coupled to two touch signal lines; the first amplifier circuit 211 is used to output a first voltage signal V1 and a second voltage signal V2 respectively based on the sensing capacitance coupled by the two touch signal lines; a second amplifier circuit 212, coupled to the first amplifier circuit 211; the second amplifier circuit 212 is used to perform a differential operation on the first voltage signal and the second voltage signal, and determine the position where the touch operation occurs according to the differential operation result.

[0056] In an embodiment of the present application, the touch circuit 200 can realize self-capacitance detection and mutual capacitance electrical measurement. Specifically, the touch circuit 200 adopts a fully differential mode and includes a two-stage amplifier circuit. Among them, the two input ends of the first amplifier circuit 211 are respectively coupled to two touch signal lines, that is, dual-channel detection is performed. Here, the two touch signal lines coupled to the first amplifier circuit can be two touch input signal lines or two touch output signal lines. The first amplifier circuit 211 is used to output a first voltage signal V1 and a second voltage signal V2 respectively based on the induced capacitance coupled by the two touch signal lines. The induced capacitance can be a self-capacitance or a mutual capacitance.

[0057] The two input terminals of the second amplifier circuit 212 are respectively coupled to the two output terminals of the first amplifier circuit 211. The second amplifier circuit 212 can perform a differential operation on the first voltage signal V1 and the second voltage signal V2, so as to determine the position where the touch operation occurs according to the differential operation result. Exemplarily, the second amplifier circuit 212 performs a first differential operation on the first voltage signal V1 and the second voltage signal V2 to output a first amplified signal OutN, and performs a second differential operation on the second voltage signal V2 and the first voltage signal V1 to output a second amplified signal OutP. In this way, the difference between the first amplified signal OutN and the second amplified signal OutP can be used to indicate whether a touch operation occurs at the position where the corresponding touch signal line is located. It can be understood that since the display noise is generally common mode noise, that is, the display noise has almost the same effect on all touch signal lines, and the second amplifier circuit 212 performs a differential operation on the first voltage signal V1 and the second voltage signal V2, the touch detection circuit 210 can effectively reduce the common mode noise of the display panel.

[0058] That is to say, the touch circuit 200 reduces the influence of display noise by performing differential operation on the signals output by the two touch signal lines on the basis of realizing self-capacitance and mutual-capacitance touch detection, which is beneficial to improving the accuracy of touch detection. In addition, since the touch circuit 200 reduces display noise, it is easier to identify changes in smaller mutual capacitance (such as less than 1 pF).

[0059] In some embodiments, the two touch signal lines coupled to the first amplifier circuit 211 may be two adjacent touch signal lines, so as to further make the common mode noise on the two touch signal lines close to each other, thereby better reducing the influence of the common mode noise through differential operation. In other embodiments, the two touch signal lines coupled to the first amplifier circuit 211 may also be two non-adjacent touch signal lines.

[0060] In some embodiments, the first amplifier circuit 211 includes an input common mode amplifier (ICMA); the input common mode amplifier is used to isolate noise coupled to the second amplifier circuit 212 through the touch signal line.

[0061] In the embodiment of the present application, the first amplifier circuit 211 may be an input common-mode amplifier and is used to isolate the touch array 220 from the second amplifier circuit 212 , thereby further reducing the influence of noise coupled to the touch array 220 on the second amplifier circuit 212 .

[0062] In some embodiments, the touch circuit also includes a common electrode; the touch signal line includes a touch input signal line and a touch output signal line that are cross-arranged; the first voltage signal and the second voltage signal are determined by the induced capacitance between the touch signal line and the common electrode; or, the first voltage signal and the second voltage signal are determined by the induced capacitance between the touch input signal line and the touch output signal line.

[0063] In the examples of this application, refer to Figure 2 , the touch circuit also includes a common electrode, such as a common electrode of a display panel. During self-capacitance detection, the first voltage signal and the second voltage signal output by the first amplifier circuit are respectively determined by the induced capacitance between the corresponding two touch input signal lines and the common electrode, or the first voltage signal and the second voltage signal output by the first amplifier circuit are respectively determined by the induced capacitance between the corresponding two touch output signal lines and the common electrode. During mutual capacitance detection, the first voltage signal and the second voltage signal output by the first amplifier circuit are determined by the induced capacitance between a corresponding touch input signal line and a touch output signal line.

[0064] In some embodiments, Figure 4 As shown, the input common-mode amplifier is further used to receive an excitation signal Vex, and output a first voltage signal V1 and a second voltage signal V2 based on the excitation signal Vex and the sensing capacitance coupled between the two touch signal lines.

[0065] In an embodiment of the present application, an excitation signal Vex can be applied to the first amplifier circuit 211, and a corresponding drive signal Vdrv can be applied to the touch signal line, so that the first amplifier circuit 211 outputs a corresponding voltage signal based on the inductive capacitance coupled to the touch signal line. Exemplarily, the excitation signal Vex is a square wave AC signal, and the drive signal Vdrv is a DC signal; or, the excitation signal Vex is a DC signal, and the drive signal Vdrv is a square wave AC signal. It should be noted that the excitation signal Vex and the drive signal Vdrv can also be other combinations, and are determined by the actual design requirements of the touch circuit 200, and are not subject to excessive restrictions here.

[0066] In some embodiments, the induced capacitance includes self-capacitance and mutual capacitance; when the touch circuit detects the self-capacitance, the excitation signal includes an AC signal; when the touch circuit detects the mutual capacitance, the excitation signal includes a DC signal.

[0067] In some embodiments, Figure 5As shown, the input common-mode amplifier includes a first input terminal in1 and a second input terminal in2 respectively coupled to two touch signal lines, and a first output terminal out1 and a second output terminal out2 coupled to the second amplifier circuit; the first input terminal in1 and the first output terminal out1 are connected through a first wire; the second input terminal in2 and the second output terminal out2 are connected through a second wire.

[0068] In the embodiment of the present application, the first input terminal in1 of the input common mode amplifier (i.e., the first amplifier circuit 211) is short-circuited with the first output terminal out1 through a first wire, and the second input terminal in2 of the input common mode amplifier is short-circuited with the second output terminal out2 through a second wire. In this way, the input common mode amplifier can ensure that the voltages of the input terminal and the output terminal are the same and have the same common mode signal amount. It can be understood that the input common mode amplifier can also be used as a buffer to reduce the pressure of the second amplifier circuit 212.

[0069] In some embodiments, Figure 5 As shown, the second amplifier circuit 212 includes a differential amplifier; the differential amplifier includes a third input terminal in3, a fourth input terminal in4, a third output terminal out3 and a fourth output terminal out4; the third input terminal in3 is used to receive the first voltage signal V1, and the fourth input terminal in4 is used to receive the second voltage signal V2; the second amplifier circuit 212 also includes: a first capacitor C1, coupled between the third input terminal in3 and the third output terminal out3; a second capacitor C2, coupled between the fourth input terminal in4 and the fourth output terminal out4; the first capacitor C1 and the second capacitor C2 are used as operational feedback capacitors for differential operations.

[0070] In the embodiment of the present application, the second amplifier circuit 212 may be a differential amplifier, such as a fully differential amplifier, wherein the first capacitor C1 is coupled between the third input terminal in3 and the third output terminal out3, and the second capacitor C2 is coupled between the fourth input terminal in4 and the fourth output terminal out4, and the two serve as operational feedback capacitors of the differential amplifier to perform proportional operations.

[0071] Figure 6 and Figure 7 Schematic diagrams of the touch control circuit 200 performing mutual capacitance detection and self-capacitance detection respectively. Figure 6 When mutual capacitance detection is performed, a first mutual capacitance Cm1 is formed between the touch input signal line coupled to the transmitter TX1 and the touch output signal line coupled to the receiver RX1, and a second mutual capacitance Cm2 is formed between the touch input signal line coupled to the transmitter TX2 and the touch output signal line coupled to the receiver RX2. It should be noted that the touch detection circuit 210 can also be coupled to touch signal lines corresponding to other transmitters and receivers. Figure 6This is only used as an example to facilitate understanding and is not intended to limit the scope of protection of the present application. In this way, the difference between the first amplified signal OutN and the second amplified signal OutP is OutP-OutN∝(Cm1-Cm2) / C1, or OutP-OutN∝(Cm1-Cm2) / C2, that is, the difference between the first amplified signal OutN and the second amplified signal OutP is proportional to the difference between the first mutual capacitance Cm1 and the second mutual capacitance Cm2. When a touch operation occurs, at least one of the first mutual capacitance Cm1 and the second mutual capacitance Cm2 changes, then OutP-OutN changes, and the touch detection circuit 210 recognizes that a touch operation has occurred.

[0072] For example, reference Figure 7 When performing self-capacitance detection, a first self-capacitance Ctx1 is formed between the touch input signal line coupled to the transmitting terminal TX1 and the common electrode (ground), and a second self-capacitance Ctx2 is formed between the touch input signal line coupled to the transmitting terminal TX2 and the common electrode (ground). It should be noted that the touch detection circuit 210 can also be coupled to touch signal lines corresponding to other transmitting terminals and receiving terminals. Figure 7 This is only used as an example to facilitate understanding and is not intended to limit the scope of protection of this application. In this way, the difference between the first amplified signal OutN and the second amplified signal OutP is OutP-OutN∝(Ctx1-Ctx2) / C1, or OutP-OutN∝(Ctx1-Ctx2) / C2, that is, the difference between the first amplified signal OutN and the second amplified signal OutP is proportional to the difference between the first self-capacitance Ctx1 and the second self-capacitance Ctx2. It can be seen from the above formula that at this time, the operation target of the second amplifier circuit 212 is Ctx1-Ctx2, compared to Figure 3 In the embodiment shown, the calculation target is changed from a single self-capacitor to the difference between two self-capacitors. Since the difference between the first self-capacitor Ctx1 and the second self-capacitor Ctx2 is small, the first capacitor C1 and the second capacitor C2 as the operational feedback capacitor can ensure that the output signal does not exceed the range when the capacitance value is small. Therefore, the occupied area of ​​the first capacitor C1 and the second capacitor C2 can be small, and the difficulty of calculation is also reduced. It can be understood that compared with Figure 3 In the embodiment shown, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 are Figure 3 When the capacitance value of the buffer capacitor remains consistent, the touch detection circuit 210 can drive a larger self-capacitance load.

[0073] In some embodiments, at least one of the first capacitor C1 and the second capacitor C2 is a variable capacitor, and the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can be adjusted according to actual needs.

[0074] In some embodiments, Figure 5As shown, the second amplifier circuit 212 also includes: a first variable resistor R1, connected in parallel with the first capacitor C1 between the third input terminal in3 and the third output terminal out3; when the amount of charge stored in the first capacitor C1 is greater than the first threshold, the first capacitor C1 is discharged through the first variable resistor R1; a second variable resistor R2, connected in parallel with the second capacitor C2 between the fourth input terminal in4 and the fourth output terminal out4; when the amount of charge stored in the second capacitor C2 is greater than the second threshold, the second capacitor C2 is discharged through the second variable resistor R2.

[0075] In the embodiment of the present application, the first variable resistor R1 and the second variable resistor R2 are used to prevent the first capacitor C1 and the second capacitor C2 from being saturated, respectively. Specifically, when the amount of charge stored in the first capacitor C1 is greater than the first threshold, the resistance value of the first variable resistor R1 can be changed from a high resistance value to a low resistance value, so that the first capacitor C1 is discharged through the first variable resistor R1; when the amount of charge stored in the second capacitor C2 is greater than the second threshold, the resistance value of the second variable resistor R2 can be changed from a high resistance value to a low resistance value, so that the second capacitor C2 is discharged through the second variable resistor R2. The first threshold and the second threshold can be set according to actual needs.

[0076] In some embodiments, the second amplifier circuit further includes: a first switch connected in parallel with the first capacitor between the third input terminal and the third output terminal; when the amount of charge stored in the first capacitor is greater than the first threshold, the first switch is closed to form a path, so that the first capacitor is discharged through the first switch; a second switch connected in parallel with the second capacitor between the fourth input terminal and the fourth output terminal; when the amount of charge stored in the second capacitor is greater than the second threshold, the second switch is closed to form a path, so that the second capacitor is discharged through the second switch. That is, the first variable resistor in the above embodiment can be replaced by the first switch, and the second variable resistor can be replaced by the second switch.

[0077] Based on the same inventive concept, Figure 8 As shown, the embodiment of the present application also provides a touch display screen 300, including: a pixel array 310 and a touch circuit 200 coupled to each other; the touch circuit 200 includes: a touch detection circuit 210 and a touch array 220 located on the pixel array 310; the touch array 220 includes touch signal lines arranged crosswise; the touch detection circuit 210 includes: a first amplifier circuit 211, coupled to two touch signal lines; the first amplifier circuit 211 is used to output a first voltage signal and a second voltage signal respectively based on the induction capacitance coupled by the two touch signal lines; a second amplifier circuit 212, coupled to the first amplifier circuit 211; the second amplifier circuit 212 is used to perform a differential operation on the first voltage signal and the second voltage signal, and determine the position where the touch operation occurs according to the differential operation result.

[0078] In the embodiment of the present application, the touch circuit 200 performs differential operation on the signals output by the two touch signal lines on the basis of realizing self-capacitance and mutual-capacitance touch detection, thereby reducing the influence of display noise and improving the accuracy of touch detection. In addition, since the touch circuit 200 reduces display noise, it is easier to identify changes in smaller mutual capacitance (such as less than 1pF).

[0079] In some embodiments, the first amplifying circuit includes an input common-mode amplifier; the input common-mode amplifier is used to isolate noise coupled to the second amplifying circuit through the touch signal line.

[0080] In some embodiments, the input common mode amplifier is further used to receive an excitation signal, and output a first voltage signal and a second voltage signal based on the excitation signal and the sensing capacitance coupled between the two touch signal lines.

[0081] In some embodiments, the input common-mode amplifier includes a first input terminal and a second input terminal respectively coupled to two touch signal lines, and a first output terminal and a second output terminal coupled to a second amplifier circuit; the first input terminal and the first output terminal are connected through a first wire; the second input terminal and the second output terminal are connected through a second wire.

[0082] In some embodiments, the second amplifier circuit includes a differential amplifier; the differential amplifier includes a third input terminal, a fourth input terminal, a third output terminal and a fourth output terminal; the third input terminal is used to receive a first voltage signal, and the fourth input terminal is used to receive a second voltage signal; the second amplifier circuit also includes: a first capacitor, coupled between the third input terminal and the third output terminal; a second capacitor, coupled between the fourth input terminal and the fourth output terminal; the first capacitor and the second capacitor are used as operational feedback capacitors for differential operations.

[0083] In some embodiments, the second amplifier circuit also includes: a first variable resistor, connected in parallel with the first capacitor between the third input terminal and the third output terminal; when the amount of charge stored in the first capacitor is greater than the first threshold, the first capacitor is discharged through the first variable resistor; a second variable resistor, connected in parallel with the second capacitor between the fourth input terminal and the fourth output terminal; when the amount of charge stored in the second capacitor is greater than the second threshold, the second capacitor is discharged through the second variable resistor.

[0084] Based on the same inventive concept, an embodiment of the present application further provides a touch control chip, including: any one of the touch control circuits in the above embodiments.

[0085] In the touch control circuit, touch display screen, and touch control chip provided in the present application, the first amplifier circuit is used to output the first voltage signal and the second voltage signal respectively based on the inductive capacitance coupled by the two touch signal lines, and the second amplifier circuit is used to perform a differential operation on the first voltage signal and the second voltage signal, and determine the position where the touch operation occurs according to the differential operation result. In this way, the touch control circuit performs a differential operation on the signals output by the two touch signal lines on the basis of completing the touch detection, thereby reducing the influence of display noise and improving the accuracy of touch detection.

[0086] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction.

[0087] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A touch control circuit, characterized in that: include: Touch detection circuit and touch array; The touch array includes touch signal lines arranged crosswise; The touch detection circuit comprises: A first amplifier circuit is coupled to the two touch signal lines; the first amplifier circuit is used to output a first voltage signal and a second voltage signal respectively based on the inductive capacitance coupled to the two touch signal lines; The second amplifier circuit is coupled to the first amplifier circuit; the second amplifier circuit is used for performing a differential operation on the first voltage signal and the second voltage signal, and determining a position where a touch operation occurs according to a differential operation result.

2. The touch control circuit according to claim 1, characterized in that: The first amplifying circuit includes an input common-mode amplifier; the input common-mode amplifier is used to isolate noise coupled to the second amplifying circuit through the touch signal line.

3. The touch control circuit according to claim 2, characterized in that: The input common-mode amplifier is further configured to receive an excitation signal, and output the first voltage signal and the second voltage signal based on the excitation signal and the sensing capacitance coupled between the two touch signal lines.

4. The touch control circuit according to claim 2, characterized in that: The input common-mode amplifier comprises a first input terminal and a second input terminal respectively coupled to the two touch signal lines, and a first output terminal and a second output terminal coupled to the second amplifier circuit; the first input terminal and the first output terminal are connected via a first wire; The second input terminal is connected to the second output terminal through a second wire.

5. The touch control circuit according to any one of claims 1 to 4, characterized in that: The second amplifying circuit comprises a differential amplifier; The differential amplifier comprises a third input terminal, a fourth input terminal, a third output terminal and a fourth output terminal; the third input terminal is used to receive the first voltage signal, and the fourth input terminal is used to receive the second voltage signal; The second amplifying circuit further includes: A first capacitor coupled between the third input terminal and the third output terminal; The second capacitor is coupled between the fourth input terminal and the fourth output terminal; the first capacitor and the second capacitor are used as operational feedback capacitors for the differential operation.

6. The touch control circuit according to claim 5, characterized in that: The second amplifying circuit further includes: a first variable resistor connected in parallel with the first capacitor between the third input terminal and the third output terminal; when the amount of charge stored in the first capacitor is greater than a first threshold, the first capacitor is discharged through the first variable resistor; A second variable resistor is connected in parallel with the second capacitor between the fourth input terminal and the fourth output terminal; when the amount of charge stored in the second capacitor is greater than a second threshold, the second capacitor is discharged through the second variable resistor.

7. A touch display screen, characterized in that: include: A pixel array and a touch control circuit coupled to each other; The touch control circuit comprises: a touch control detection circuit and a touch control array located on the pixel array; the touch control array comprises touch control signal lines arranged crosswise; The touch detection circuit comprises: A first amplifier circuit is coupled to the two touch signal lines; the first amplifier circuit is used to output a first voltage signal and a second voltage signal respectively based on the inductive capacitance coupled to the two touch signal lines; The second amplifier circuit is coupled to the first amplifier circuit; the second amplifier circuit is used for performing a differential operation on the first voltage signal and the second voltage signal, and determining a position where a touch operation occurs according to a differential operation result.

8. The touch display screen according to claim 7, characterized in that: The first amplifying circuit includes an input common-mode amplifier; the input common-mode amplifier is used to isolate noise coupled to the second amplifying circuit through the touch signal line.

9. The touch display screen according to claim 8, characterized in that: The input common-mode amplifier is further configured to receive an excitation signal, and output the first voltage signal and the second voltage signal based on the excitation signal and the sensing capacitance coupled between the two touch signal lines.

10. The touch display screen according to claim 8, characterized in that: The input common-mode amplifier comprises a first input terminal and a second input terminal respectively coupled to the two touch signal lines, and a first output terminal and a second output terminal coupled to the second amplifier circuit; the first input terminal and the first output terminal are connected via a first wire; The second input terminal is connected to the second output terminal through a second wire.

11. The touch display screen according to any one of claims 7 to 10, characterized in that: The second amplifying circuit comprises a differential amplifier; The differential amplifier comprises a third input terminal, a fourth input terminal, a third output terminal and a fourth output terminal; the third input terminal is used to receive the first voltage signal, and the fourth input terminal is used to receive the second voltage signal; The second amplifying circuit further includes: A first capacitor coupled between the third input terminal and the third output terminal; The second capacitor is coupled between the fourth input terminal and the fourth output terminal; the first capacitor and the second capacitor are used as operational feedback capacitors for the differential operation.

12. The touch display screen according to claim 11, characterized in that: The second amplifying circuit further includes: a first variable resistor connected in parallel with the first capacitor between the third input terminal and the third output terminal; when the amount of charge stored in the first capacitor is greater than a first threshold, the first capacitor is discharged through the first variable resistor; A second variable resistor is connected in parallel with the second capacitor between the fourth input terminal and the fourth output terminal; when the amount of charge stored in the second capacitor is greater than a second threshold, the second capacitor is discharged through the second variable resistor.

13. A touch chip, characterized in that: include: The touch control circuit according to any one of claims 1 to 6.

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