Touch detection circuit, touch chip and screen module

Abstract

The embodiment of the utility model provides a touch detection circuit, a touch chip and a screen module. The touch detection circuit is connected with a plurality of electrodes; the touch detection circuit is used for processing input signals input by the electrodes to obtain touch signals corresponding to the electrodes, and the touch signals are used for indicating touch states of touch areas where the electrodes are located; when the finger is not touched, the touch signal corresponding to the electrode is a first touch signal; when a finger touches, the touch signal corresponding to the electrode in the touch area touched by the finger is a second touch signal, the touch signal corresponding to the electrode in the touch area not touched by the finger is a third touch signal, and the second touch signal and the third touch signal are different from the first touch signal. According to the scheme, the accuracy of touch recognition can be improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electronic technology, and in particular to a touch detection circuit, a touch chip and a screen module. Background Art

[0002] As screen size increases and screen manufacturing technology advances, the coupling between screen touch sensors and display interference becomes more and more serious. The display interference coupled to the screen touch sensor increases, which reduces the signal-to-noise ratio (SNR) of the touch signal obtained by the screen touch sensor. As a result, when touch recognition is performed through the touch signal, the accuracy of touch recognition is low.

[0003] Currently, effective touch signals in the touch signals are identified by amplifying the touch signals.

[0004] However, the display interference coupled to the screen touch sensor is large, so the display interference occupies most of the dynamic range of the touch signal, while the effective touch signal only occupies a small part of the dynamic range. After amplifying the touch signal, the effective touch signal is still small, and thus the accuracy of touch detection based on the effective touch signal is still low. Utility Model Content

[0005] In view of this, embodiments of the present application provide a touch detection circuit, a touch chip and a screen module to at least partially solve the above problems.

[0006] According to a first aspect of an embodiment of the present application, a touch detection circuit is provided, which is connected to a plurality of electrodes; the touch detection circuit is used to process input signals input by the plurality of electrodes to obtain a touch signal corresponding to each of the electrodes, wherein the touch signal is used to indicate a touch state of a touch area where the electrode is located; when a finger is not touching, the touch signal corresponding to the electrode is a first touch signal; when a finger is touching, the touch signal corresponding to the electrode in the touch area touched by the finger is a second touch signal, and the touch signal corresponding to the electrode in the touch area not touched by the finger is a third touch signal, and both the second touch signal and the third touch signal are different from the first touch signal.

[0007] In a possible implementation, the signal amount of the second touch signal is negatively correlated with the number of the electrodes located in the touch area touched by the finger, and the signal amount of the third touch signal is positively correlated with the number of the electrodes located in the touch area touched by the finger.

[0008] In a possible implementation manner, when different numbers of the electrodes are located in the touch area touched by the finger, the sum of the signal amounts of the second touch signal and the third touch signal is the same.

[0009] In a possible implementation, the touch detection circuit includes an analog-to-digital conversion module, and the touch signal is output by the analog-to-digital conversion module.

[0010] In a possible implementation, the touch detection circuit includes: an amplification module and a feedback module; the amplification module includes multiple amplification sub-modules, and different amplification sub-modules are connected to different electrodes; the feedback module is used to generate an error signal according to the output signal output by each amplification sub-module, and transmit the error signal to each amplification sub-module respectively, wherein the error signal is used to indicate the average strength of the interference signal coupled to each electrode; the amplification sub-module is used to output the output signal according to the input signal input by the electrode connected to the amplification sub-module and the error signal, wherein the output signal is used to generate the touch signal corresponding to the electrode connected to the amplification sub-module.

[0011] In a possible implementation, the feedback module includes an accumulation submodule, a switching submodule and a mean amplification submodule; the multiple input terminals of the accumulation submodule are respectively connected to each of the amplification submodules; the two input terminals of the mean amplification submodule are respectively connected to the accumulation submodule and the switching submodule, and the output terminal of the mean amplification submodule is respectively connected to the input terminal of each of the amplification submodules; the accumulation submodule is used to obtain an accumulated current according to the output signal of each of the amplification submodules, and transmit the accumulated current to the mean amplification submodule, wherein the accumulated current is used to indicate the total intensity of the interference signal coupled to each of the electrodes; the switching submodule is used to transmit a reference voltage signal to the mean amplification submodule; the mean amplification submodule is used to generate the error signal according to the accumulated current and the reference voltage signal, and transmit the error signal to each of the amplification submodules.

[0012] In a possible implementation, the amplification submodule includes a first amplifier, a first resistor, a second resistor and a first capacitor; the first end of the first resistor is connected to the electrode, and the second end of the first resistor is connected to the inverting input of the first amplifier; the first end of the second resistor is connected to the inverting input of the first amplifier, and the second end of the second resistor is connected to the output of the first amplifier; the first end of the first capacitor is connected to the inverting input of the first amplifier, and the second end of the first capacitor is connected to the output of the first amplifier; the in-phase input of the first amplifier is connected to the mean amplification submodule, and the output of the first amplifier is connected to the accumulation submodule, the first amplifier transmits the output signal to the accumulation submodule through the output, and the mean amplification submodule transmits the error signal to the in-phase input of the first amplifier.

[0013] In a possible implementation, the accumulation submodule includes multiple third resistors; the first end of the third resistor is connected to the output end of the first amplifier, the second end of the third resistor is connected to the input end of the mean amplification submodule, the first ends of different third resistors are connected to different first amplifiers, and the second ends of different third resistors are connected to the same input end of the mean amplification submodule.

[0014] In a possible implementation, the mean amplification submodule includes: a second amplifier, a second capacitor, a third capacitor, a fourth resistor and a fifth resistor; the in-phase input terminal of the second amplifier is connected to the switching submodule, the inverting input terminal of the second amplifier is connected to the first end of the fifth resistor, and the second end of the fifth resistor is respectively connected to the second end of each of the third resistors; the output terminal of the second amplifier is respectively connected to the in-phase input terminal of each of the first amplifiers, the first end of the fourth resistor is connected to the output terminal of the second amplifier, the second end of the fourth resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is connected to the inverting input terminal of the second amplifier; the first end of the second capacitor is connected to the output terminal of the second amplifier, and the second end of the second capacitor is connected to the inverting input terminal of the second amplifier.

[0015] In a possible implementation, the mean amplification submodule includes: a third amplifier, a fourth capacitor, a fifth capacitor, a sixth capacitor, a sixth resistor, a seventh resistor and an eighth resistor; the in-phase input terminal of the third amplifier is connected to the switching submodule, the inverting input terminal of the third amplifier is connected to the first end of the eighth resistor, and the second end of the eighth resistor is respectively connected to the second end of each of the third resistors; the output terminal of the third amplifier is respectively connected to the in-phase input terminal of each of the first amplifiers, the first end of the sixth resistor is connected to the output terminal of the third amplifier, the second end of the sixth resistor is connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the first end of the fourth capacitor, the second end of the fourth capacitor is connected to the first end of the seventh resistor, and the second end of the seventh resistor is connected to the second end of the eighth resistor; the first end of the sixth capacitor is connected to the output terminal of the third amplifier, and the second end of the sixth capacitor is respectively connected to the second end of the fifth capacitor and the inverting input terminal of the third amplifier.

[0016] In a possible implementation, the mean amplification submodule includes: a fourth amplifier, a seventh capacitor, an eighth capacitor, a ninth resistor, a tenth resistor and an eleventh resistor; the in-phase input terminal of the fourth amplifier is connected to the switching submodule, the inverting input terminal of the fourth amplifier is connected to the first end of the eleventh resistor, and the second end of the eleventh resistor is respectively connected to the second end of each of the third resistors; the output end of the fourth amplifier is respectively connected to the in-phase input end of each of the first amplifiers, the first end of the ninth resistor is connected to the output end of the fourth amplifier, the second end of the ninth resistor is connected to the first end of the eighth capacitor, the second end of the eighth capacitor is respectively connected to the first end of the seventh capacitor and the inverting input terminal of the fourth amplifier, the second end of the seventh capacitor is connected to the first end of the tenth resistor, and the second end of the tenth resistor is connected to the second end of the eleventh resistor.

[0017] In a possible implementation, the mean amplification submodule includes: a fifth amplifier, a ninth capacitor, a twelfth resistor and a thirteenth resistor; the non-inverting input terminal of the fifth amplifier is connected to the switching submodule, the inverting input terminal of the fifth amplifier is connected to the first end of the thirteenth resistor, and the second end of the thirteenth resistor is respectively connected to the second end of each of the third resistors; the first end of the twelfth resistor is connected to the output terminal of the fifth amplifier, the second end of the twelfth resistor is connected to the first end of the ninth capacitor, and the second end of the ninth capacitor is connected to the inverting input terminal of the fifth amplifier.

[0018] In a possible implementation, the switching submodule includes: a first DC voltage source, a first coding unit, a first switch, and a second switch; the output end of the switching submodule is respectively connected to the first end of the first switch and the first end of the second switch, the second end of the first switch is connected to the first DC voltage source, and the second end of the second switch is connected to the first coding unit; in mutual capacitance mode, the first switch is closed and the second switch is opened, and the first DC voltage source transmits a DC voltage to the output end of the switching submodule as the reference voltage signal; in self-capacitance mode, the first switch is opened and the second switch is closed, and the first coding unit transmits a self-capacitance coding signal to the output end of the switching submodule as the reference voltage signal, wherein the self-capacitance coding signal output by the first coding unit is the same as the coding signal acting on the electrode.

[0019] In a possible implementation, the touch detection circuit also includes multiple processing modules, the processing modules include a filter, a sample and hold, and a buffer submodule; the output end of the filter is connected to the input end of the sample and hold, the output end of the sample and hold is connected to the input end of the buffer submodule, and the output end of the buffer submodule is connected to the input end of the analog-to-digital conversion module, wherein the second ends of different third resistors are connected to the input ends of the filters in different processing modules, and the output ends of the buffer submodules in different processing modules are connected to the input ends of different analog-to-digital conversion modules; the filter is used to filter the input signal and remove the reference voltage signal included in the input signal to obtain a touch voltage signal; the sample and hold is used to sample the touch voltage signal to obtain a target signal and hold the target signal; the buffer submodule is used to transmit the target signal unchanged to the analog-to-digital conversion module, so that the analog-to-digital conversion module converts the target signal into the touch signal.

[0020] In a possible implementation manner, the in-phase input terminal of each of the first amplifiers is connected to the input terminal of the filter in one of the processing modules.

[0021] In a possible implementation, the filter includes: a differential amplifier, a second DC voltage source, a second coding unit, a third switch, a fourth switch, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a tenth capacitor, an eleventh capacitor and a twelfth capacitor; the first end of the fourteenth resistor is connected to the second end of the third resistor, wherein the second ends of different third resistors are connected to the first ends of the fourteenth resistors in different filters; the second end of the fourteenth resistor is connected to the first end of the sixteenth resistor, the second end of the sixteenth resistor is connected to the positive input end of the differential amplifier, the first end of the seventeenth resistor is connected to the first end of the sixteenth resistor, the second end of the seventeenth resistor is connected to the negative output end of the differential amplifier, the first end of the eleventh capacitor is connected to the second end of the sixteenth resistor, and the second end of the eleventh capacitor is connected to the negative output end of the differential amplifier; the first end of the fifteenth resistor is connected to the first end of the third switch and the first end of the fourth switch respectively, and the second end of the third switch is connected to the positive input end of the differential amplifier. The second DC voltage source is connected, the second end of the fourth switch is connected to the second coding unit; the second end of the fifteenth resistor is connected to the first end of the eighteenth resistor, the second end of the eighteenth resistor is connected to the negative input terminal of the differential amplifier, the first end of the nineteenth resistor is connected to the first end of the eighteenth resistor, the second end of the nineteenth resistor is connected to the positive output terminal of the differential amplifier, the first end of the twelfth capacitor is connected to the second end of the eighteenth resistor, and the second end of the twelfth capacitor is connected to the positive output terminal of the differential amplifier; the first end of the tenth capacitor is connected to the first end of the sixteenth resistor, the second end of the tenth capacitor is connected to the first end of the eighteenth resistor, and the positive output terminal and the negative output terminal of the differential amplifier are respectively connected to the sample and hold; in the mutual capacitance mode, the third switch is closed and the fourth switch is opened, and the second DC voltage source outputs a DC voltage identical to the reference voltage signal; in the self-capacitance mode, the third switch is opened and the fourth switch is closed, and the second coding unit outputs a coding signal identical to the reference voltage signal.

[0022] According to a second aspect of an embodiment of the present application, a touch control chip is provided, comprising the touch control detection circuit described in the first aspect.

[0023] According to a third aspect of an embodiment of the present application, a screen module is provided, comprising: a plurality of electrodes and a touch chip as described in the second aspect above; the electrodes are used to receive touch drive signals output by the touch chip so that the screen module recognizes touch commands, wherein the electrodes are horizontal electrodes and / or vertical electrodes arranged on the touch screen.

[0024] According to the solution of the embodiment of the present application, the touch detection circuit can sum the output signals of each electrode and use the previous stage feedback mean error method to suppress display interference and basic signals, so that the effective touch signal has a larger dynamic range and improves the accuracy of touch recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0026] Figure 1 is a schematic diagram of a touch detection circuit according to an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of a touch detection circuit according to another embodiment of the present application;

[0028] Figure 3 is a schematic diagram of a touch detection circuit according to another embodiment of the present application;

[0029] Figure 4 is a schematic diagram of a touch detection circuit according to yet another embodiment of the present application;

[0030] Figure 5 This is a schematic diagram of the circuit structure of a mean value amplifier module provided in one embodiment of the present application;

[0031] Figure 6 is a schematic diagram of the circuit structure of a mean value amplification submodule according to another embodiment of the present application;

[0032] Figure 7 Schematic diagram of the circuit structure of a mean value amplifier module in another embodiment of the present application;

[0033] Figure 8 1 is a schematic diagram of the circuit structure of a mean value amplification submodule of another embodiment of the present application;

[0034] Fig. 9 is a schematic diagram of a phase margin evaluation result of an embodiment of the present application;

[0035] Fig.10 It is a schematic diagram of the mutual-capacitance coding base suppression effect of an embodiment of the present application;

[0036] Fig.11 is a schematic diagram showing the interference suppression effect of an embodiment of the present application;

[0037] Fig.12is a schematic diagram of a mutual capacitance touch diff effect according to an embodiment of the present application;

[0038] Fig.13 is a schematic diagram of a mutual-capacitive touch diff effect according to another embodiment of the present application;

[0039] Fig.14 is a schematic diagram of a self-capacitive touch diff effect of an embodiment of the present application;

[0040] Fig.15 is a schematic diagram of a self-capacitive touch diff effect of another embodiment of the present application;

[0041] Fig.16 It is a schematic diagram of a screen module according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the embodiments of the present application should fall within the scope of protection of the embodiments of the present application.

[0043] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0044] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0045] Touch detection circuit

[0046] Figure 1 FIG. 1 is a schematic diagram of the connection between the touch detection circuit and the electrodes on the touch screen in a touch chip according to an embodiment of the present application. Figure 1As shown, the touch detection circuit 10 is connected to a plurality of electrodes 20. The touch detection circuit 10 can receive and process input signals from the electrodes 10 to obtain touch signals corresponding to each electrode, and the touch signals can indicate the touch state of the touch area where the corresponding electrode is located.

[0047] A touch signal corresponding to an electrode when the finger is not touching is defined as a first touch signal. A touch signal corresponding to an electrode located in a touch area touched by the finger when the finger is touching is defined as a second touch signal, and a touch signal corresponding to an electrode located in a touch area not touched by the finger when the finger is touching is defined as a third touch signal. The first touch signal, the second touch signal, and the third touch signal meet the following conditions: the second touch signal and the third touch signal are both different from the first touch signal.

[0048] The electrodes 20 on the touch screen may include horizontal electrodes and vertical electrodes arranged therein. When a finger touches the touch screen, the coupling capacitance of the electrode located in the touch area touched by the finger changes, thereby changing the touch signal corresponding to the electrode. The touch position of the finger on the touch screen can be determined based on the touch signal corresponding to each electrode, thereby realizing touch detection.

[0049] When a finger touches the touch screen, the touch signal corresponding to the electrode in the touch area touched by the finger is the second touch signal, while the touch signal corresponding to the electrode in the touch area not touched by the finger is the third touch signal. The second touch signal is different from the third touch signal, and thus the touch area of ​​the finger on the touch screen can be determined based on the touch area on the touch screen where the electrode corresponding to the touch signal is the second touch signal.

[0050] When performing touch detection, the touch area can be determined according to the touch change amount corresponding to each electrode. The touch change amount can be calculated according to the touch signal corresponding to the electrode. In one example, the first touch signal is used as a reference signal, and the difference between the touch signal corresponding to the electrode and the first touch signal is used as the touch change amount. When the finger is not touching, the touch signal corresponding to the electrode is the first touch signal, and the touch change amount is equal to 0. When the finger touches, the touch change amount corresponding to the electrode in the touch area touched by the finger is the difference between the second touch signal and the first touch signal, and the touch change amount corresponding to the electrode in the touch area not touched by the finger is the difference between the third touch signal and the first touch signal. When the finger touches the touch screen, the touch change amount corresponding to the electrode in the touch area touched by the finger and the electrode in the touch area not touched by the finger is different, and then the touch area of ​​the finger can be determined according to the touch change amount corresponding to each electrode.

[0051] The electrode 20 may include a horizontal electrode and a vertical electrode arranged on the touch screen, and the horizontal electrode is arranged vertically to the vertical electrode. For a capacitive touch screen, when performing touch recognition, a self-capacitance mode, a mutual capacitance mode, and a self-mutual capacitance combined mode may be used for touch recognition. In the self-capacitance mode, a touch signal is generated based on a change in the capacitance value of the driving electrode to the ground capacitance, and in the mutual capacitance mode, a touch signal is generated based on a change in the capacitance value of the capacitance between the driving electrode and the sensing electrode. The electrode 20 will couple display interference, and in the self-capacitance mode, when there is no finger touch, the electrode will also generate a basic signal (coding base) due to its own capacitance to the ground (or coupling capacitance), so when touching, the output signal of the electrode 20 includes display interference, basic signal and effective touch signal, and the effective touch signal is used for touch recognition. Relative to the effective touch signal, the display interference and the basic signal are interference signals.

[0052] When coding, the basic signal and display interference will occupy the dynamic range. The main purpose of this solution is to eliminate or reduce the impact of the basic signal and display interference on the dynamic range, so that only the effective touch signal during touch is amplified to obtain a larger SNR.

[0053] The display interferences coupled to different electrodes 20 are substantially the same, and the basic signals on different electrodes 20 are also substantially the same.

[0054] In the self-capacitance mode, the electrode 20 includes the transverse electrodes and the longitudinal electrodes on the touch screen. In the mutual-capacitance mode, the electrode 20 includes the sensing electrodes on the touch screen.

[0055] The touch detection circuit 10 can sum the signals output by each electrode 20, and then feedback the mean error corresponding to each electrode 20 based on the summation result to suppress the display interference and basic signal in the signal output by each electrode 20, so that the effective touch detection signal has a larger dynamic range. When the finger does not touch the touch screen, the output signals output by each electrode 20 are consistent, and the touch signals corresponding to each electrode 20 are still consistent after the mean error is fed back, that is, when the finger is touching, the touch signals corresponding to each electrode 20 are all first touch signals. When a finger touches the touch screen, the output signal output by the electrode 20 located in the touch area touched by the finger is different from the output signal output by the electrode 20 located in the touch area not touched by the finger. After the mean error is fed back, the touch signals corresponding to the electrodes 20 located in the touch area touched by the finger and not touched by the finger are changed relative to the first touch signal, so that the touch signal corresponding to the electrode 20 located in the touch area touched by the finger is the second touch signal, and the touch signal corresponding to the electrode 20 located in the touch area not touched by the finger is the third touch signal, and the second touch signal is different from the third touch signal.

[0056] In the embodiment of the present application, the touch detection circuit 10 can sum the output signals of each electrode 20 and then suppress display interference and basic signals by using the previous stage feedback mean error method, so that the effective touch signal has a larger dynamic range and improves the accuracy of touch recognition.

[0057] In a possible implementation, the signal amount of the second touch signal is negatively correlated with the number of electrodes 20 located in the touch area touched by the finger, and the signal amount of the third touch signal is positively correlated with the number of electrodes 20 located in the touch area touched by the finger.

[0058] When the display interference and basic signal are suppressed by using the front-stage feedback mean error method, the touch signal corresponding to the electrode 20 located in the touch area touched by the finger is equal to the difference between the touch signal before suppression and the mean error, and the touch signal corresponding to the electrode 20 located in the touch area not touched by the finger is equal to the sum of the touch signal before suppression and the mean error. The mean error is positively correlated with the number of electrodes 20 located in the touch area touched by the finger, so the second touch signal is negatively correlated with the number of electrodes 20 located in the touch area touched by the finger, and the signal amount of the third touch signal is positively correlated with the number of electrodes 20 located in the touch area touched by the finger.

[0059] When a finger touches, the touch signal before suppression corresponding to the electrode 20 located in the touch area not touched by the finger is equal to 0, so the third touch signal is equal to the mean error.

[0060] In an embodiment of the present application, the signal amount of the second touch signal is negatively correlated with the number of electrodes 20 located in the touch area touched by the finger, while the signal amount of the third touch signal is positively correlated with the number of electrodes 20 located in the touch area touched by the finger, ensuring that display interference and basic signals can be effectively suppressed when the touch screen is touched in a small area and the touch screen is touched in a large area, thereby improving the accuracy of touch recognition.

[0061] In a possible implementation, when different numbers of electrodes 20 are located in the touch area touched by the finger, the sum of the signal amounts of the second touch signal and the third touch signal is equal.

[0062] The touch signal corresponding to the electrode 20 located in the touch area touched by the finger is equal to the difference between the touch signal before suppression and the mean error, that is, the second touch signal is equal to the difference between the touch signal before suppression and the mean error of the corresponding electrode 20. The touch signal corresponding to the electrode 20 located in the touch area not touched by the finger is equal to the sum of the touch signal before suppression and the mean error, that is, the third touch signal is equal to the sum of the touch signal before suppression and the mean error of the corresponding electrode 20. When a finger touches, the suppression pre-touch signal corresponding to the electrode 20 located in the touch area not touched by the finger is equal to 0, so the third touch signal is equal to the mean error, and then the sum of the second touch signal and the third touch signal is equal to the suppression pre-touch signal corresponding to the electrode 20 located in the touch area touched by the finger, and the suppression pre-touch signal corresponding to the electrode 20 located in the touch area touched by the finger is a constant, so the sum of the second touch signal and the third touch signal is independent of the number of electrodes 20 located in the touch area touched by the finger, and the sum of the signal amounts of the second touch signal and the third touch signal is always equal to the suppression pre-touch signal corresponding to the electrode 20 located in the touch area touched by the finger.

[0063] In one example, the second touch signal The third touch signal The mean error is equal to V0 represents the touch signal before suppression of the electrode 20 located in the touch area touched by the finger, N represents the number of electrodes 20, and n represents the number of electrodes 20 located in the touch area touched by the finger. It can be seen that V2+V3=V0, which is independent of the number of electrodes 20 located in the touch area touched by the finger.

[0064] In the embodiment of the present application, when different numbers of electrodes 20 are located in the touch area touched by the finger, the sum of the signal amounts of the second touch signal and the third touch signal is equal, and display interference and basic signals can be effectively suppressed when the finger touches a small area or a large area, so that touch recognition can be accurately performed when the finger touches a small area or a large area, thereby ensuring the accuracy of touch recognition.

[0065] In a possible implementation, the touch detection circuit 10 includes an analog-to-digital conversion module, and the touch signal is output by the analog-to-digital conversion module, that is, the touch signal corresponding to each electrode 20 can be detected through the output end of the analog-to-digital conversion module.

[0066] In one example, the touch signal corresponding to each electrode 20 may be accessed through a serial peripheral interface (SPI).

[0067] In an embodiment of the present application, the touch detection circuit 10 includes an analog-to-digital conversion module, which can convert an analog signal into a digital signal, thereby obtaining a touch signal in the form of a digital signal, so that a microcontroller unit (MCU) can determine the finger touch position according to the touch signal in the form of a digital signal.

[0068] Figure 2 FIG. 1 is a schematic diagram of a touch detection circuit according to another embodiment of the present application. Figure 2 As shown, the touch detection circuit 10 includes an amplification module 11 and a feedback module 12 . The amplification module 11 includes a plurality of amplification submodules 111 , and different amplification submodules 111 are connected to different electrodes 20 .

[0069] A feedback module 12 is connected to the output ends of multiple amplifier modules 111. The feedback module 12 can generate an error signal based on the output signal output by each amplifier module 111, and transmit the error signal to each amplifier module 111 respectively. The error signal can indicate the average strength of the interference signal coupled to each electrode 20. After receiving the input signal and the error signal input by the connected electrode 20, the amplifier module 111 can output an output signal based on the received input signal and the error signal. The output signal is used to generate a touch signal corresponding to the electrode 20 connected to the amplifier module 111.

[0070] In an embodiment of the present application, the amplifier submodule 111 can output an output signal based on the input signal from the electrode 20, and the feedback module 12 can generate an error signal based on the output signal of each amplifier submodule 111, so that the error signal can indicate the average strength of the interference signal coupled to each electrode 20, and then after the error signal is fed back to the amplifier submodule 111, the amplifier submodule 111 can suppress the interference signal in the input signal according to the error signal, thereby reducing the interference signal in the output signal, so that the effective touch signal in the output signal has a larger dynamic range, and then when touch recognition is performed based on the output signal, the accuracy of touch recognition can be improved.

[0071] In a possible implementation, the feedback module 12 may accumulate the output signals of the amplifying submodules 111 and then obtain the average of the accumulated results as the error signal.

[0072] Figure 3 FIG. 1 is a schematic diagram of a touch detection circuit 10 according to another embodiment of the present application. Figure 3 As shown, the feedback module 12 includes an accumulation submodule 121 , a switching submodule 122 and a mean value amplification submodule 123 .

[0073] Multiple input terminals of the accumulation submodule 121 are respectively connected to each amplifier submodule 111 . Two input terminals of the mean value amplifier submodule 123 are respectively connected to the accumulation submodule 121 and the switching submodule 122 , and the output terminal of the mean value amplifier submodule 123 is respectively connected to the input terminal of each amplifier submodule 111 .

[0074] The accumulation submodule 121 can obtain an accumulated current according to the output signal of each amplification submodule 111, and transmit the accumulated current to the mean amplification submodule 123. The accumulated current can indicate the total strength of the interference signal coupled to each electrode 20. The switching submodule 122 can transmit a reference voltage signal to the mean amplification submodule 123. The mean amplification submodule 123 can generate an error signal according to the accumulated current and the reference voltage signal, and transmit the error signal to each amplification submodule 111 respectively.

[0075] The output signal of the amplifying submodule 111 is a voltage signal. The accumulating submodule 121 can convert the voltage signal into a current signal, and then accumulate the converted current signals to obtain an accumulated current, so that the accumulated current can indicate the total strength of the interference signal coupled by each electrode 20.

[0076] Since the touch control chip is usually powered by a single power supply, the switching submodule 122 transmits a reference voltage signal as a bias to the average amplifier submodule 123, so that the average amplifier submodule 123 averages and amplifies the reference voltage signal and the accumulated current, and the generated error signal is a positive signal, thereby making the output signal of the amplifier submodule 111 also a positive signal, ensuring that the subsequent circuit can process normally.

[0077] The mean amplifier module 123 generates an error signal indicating the average strength of the interference signal coupled to each electrode 20 based on the reference voltage signal and the accumulated current, and makes the error signal a positive signal. After the error signal is fed back to each amplifier module 111 respectively, the amplifier module 111 can suppress the interference signal in the input signal based on the error signal, thereby reducing the interference signal in the output signal of the amplifier module 111.

[0078] In an embodiment of the present application, the accumulation submodule 121 obtains an accumulated current based on the output signal of each amplifier module 111, so that the accumulated current can indicate the total strength of the interference signal coupled to each electrode. After the accumulated current is transmitted to the mean amplifier module 123, the mean amplifier module 123 obtains an error signal through amplification, so that the error signal can be an average strength indicating the interference signal coupled to each electrode 20. After the error signal is fed back to each amplifier module 111 respectively, the amplifier module 111 suppresses the display interference and the basic signal in the input signal, thereby reducing the interference signal included in the output signal of the amplifier module 111.

[0079] In a possible implementation, the amplification submodule 111 may suppress display interference and basic signals in the input signal by means of negative feedback.

[0080] Figure 4 FIG. 1 is a schematic diagram of a touch detection circuit according to another embodiment of the present application. Figure 4 As shown, the amplifying submodule 111 includes a first amplifier A1, a first resistor R1, a second resistor R2 and a first capacitor C1.

[0081] The first end of the first resistor R1 is connected to the electrode 20, and the second end of the first resistor R1 is connected to the inverting input end of the first amplifier A1. The electrodes RX0-RXn are respectively connected to different amplifier modules 111, and the first ends of the first resistors R1 in different amplifier modules 111 are connected to different electrodes 20, for example, the electrode RX0, the electrode RX1 and the electrode RXn are connected to the first ends of different first resistors R1.

[0082] A first end of the second resistor R2 is connected to the inverting input end of the first amplifier A1 , and a second end of the second resistor R2 is connected to the output end of the first amplifier A1 .

[0083] A first end of the first capacitor C1 is connected to an inverting input end of the first amplifier A1 , and a second end of the first capacitor C1 is connected to an output end of the first amplifier A1 .

[0084] The non-inverting input terminal of the first amplifier A1 is connected to the mean amplification submodule 123, and the non-inverting input terminals of the multiple first amplifiers A1 are connected to the output terminal of an average amplification submodule 123. The output terminal of the first amplifier A1 is connected to the accumulation submodule 121, and the output terminals of the multiple first amplifiers A1 are respectively connected to the multiple input terminals of an accumulation submodule 121. The first amplifier A1 transmits the output signal to the accumulation submodule 121 through the output terminal, and the average amplification submodule 123 transmits the error signal to the non-inverting input terminal of the first amplifier A1.

[0085] The amplifier module 111 includes a first amplifier A1, the inverting input terminal of the first amplifier A1 is connected to the electrode 20 through a first resistor R1, and the voltage signal output by the electrode 20 is converted into a current signal after passing through the first resistor R1 and input into the first amplifier A1. The first amplifier A1 outputs a voltage signal, so the amplifier module 111 is implemented as a transimpedance amplifier.

[0086] It should be noted that the first amplifier A1 may be a programmable gain amplifier (PGA).

[0087] In the embodiment of the present application, the amplifier module 111 includes a first amplifier A1, the non-inverting input terminal of the first amplifier A1 is connected to the mean amplifier module 123, and the inverting input terminal of the first amplifier A1 is connected to the electrode 20 through the first resistor R1. The mean amplifier module 123 transmits the error signal to the non-inverting input terminal of the first amplifier A1, and the input signal input by the electrode 20 is input to the inverting input terminal of the first amplifier A1 after passing through the first resistor R1. When the amplifier module 111 reaches a steady state, the non-inverting input terminal and the inverting input terminal of the first amplifier A1 are virtually shorted, and the interference signal in the voltage signal input to the inverting input terminal of the first amplifier A1 is suppressed, so that the voltage signal output from the first amplifier A1 includes less interference signal, and the interference signal in the input signal is eliminated by negative feedback, so that the effective touch signal in the voltage signal output by the first amplifier A1 has a larger dynamic range, and the voltage signal output by the first amplifier A1 is used for touch recognition after being processed by the post-stage circuit, thereby improving the accuracy of touch recognition.

[0088] In one possible implementation, Figure 4 As shown, the accumulation submodule 121 includes a plurality of third resistors R3, a first end of the third resistor R3 is connected to the output end of the first amplifier A1, and a second end of the third resistor R3 is connected to the input end of the mean amplification submodule 123. Each third resistor R3 in the plurality of third resistors R3 can be matched with each first amplifier A1 respectively, a first end of different third resistors R3 is connected to the output end of different first amplifiers A1, and a second end of different third resistors R3 is connected to the same input end of the mean amplification submodule 123.

[0089] The third resistors R3 may have the same resistance value or different resistance values. The embodiment of the present application does not limit the resistance value of the third resistors R3.

[0090] In the embodiment of the present application, the amplifier module 111 is implemented as a transimpedance amplifier, and the first amplifier A1 outputs a voltage signal, which is converted into a current signal through the third resistor R3, and the second end of each third resistor R3 is connected to the same input end of the mean amplifier module 123, that is, the current input to the mean amplifier module 123 by the accumulation module 121 is the accumulated current of each channel. Since the voltage signal output by the first amplifier A1 includes an interference signal, the current signal converted by the voltage signal after passing through the third resistor R3 also includes the interference signal, so the accumulated current can indicate the total strength of the interference signal coupled to each electrode 20. Since the interference signals coupled to different electrodes 20 are basically the same, the error signal indicating the average strength of the interference signal coupled to each electrode 20 is determined based on the accumulated current, ensuring that the error signal can more accurately reflect the interference signal coupled to the electrode 20.

[0091] In a possible implementation, the mean amplification submodule 123 obtains the mean error (error signal) of different channels by amplification, and then feeds it back to the amplification submodule 111 of each channel for display interference and basic signal suppression. Figure 4 As shown, the mean amplification submodule 123 includes an amplifier 1231 and a loop stability compensation unit 1232. When the resistance values ​​of the third resistors R3 are the same, the ratio of the resistance value of the third resistor R3 to the resistance value of the loop stability compensation unit 1232 is equal to the number of the third resistors R3. Each amplification submodule 111 and the accumulation submodule 121, the switching submodule 122 and the mean amplification submodule 123 can form a feedback loop. The loop stability compensation unit 1232 can achieve stability compensation for the feedback loop through a combination of resistors and capacitors, so that the phase margin is greater than 45° and the gain margin is greater than 10Db, thereby ensuring that the feedback loop will not self-oscillate and ensuring the stability of the touch detection circuit 10 in processing the touch signal.

[0092] Since the loop stability compensation unit 1232 can achieve stability compensation for the feedback loop through a combination of resistors and capacitors, the loop stability compensation unit 1232 has a variety of different forms, thereby enabling the mean amplification submodule 123 to have a variety of circuit structures. Figures 5 to 8 Four circuit structures of the mean value amplifying submodule 123 are shown, and possible circuit structures of the mean value amplifying submodule 123 are described below.

[0093] like Figure 5 As shown, the mean amplification submodule 123 includes a second amplifier A2, a second capacitor C2, a third capacitor C3, a fourth resistor R4 and a fifth resistor R5. The in-phase input terminal of the second amplifier A2 is connected to the switching submodule 122, the inverting input terminal of the second amplifier A2 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is respectively connected to the second end of each third resistor R3. The output terminal of the second amplifier A2 is respectively connected to the in-phase input terminal of each first amplifier A1, the first end of the fourth resistor R4 is connected to the output terminal of the second amplifier A2, the second end of the fourth resistor R4 is connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is connected to the inverting input terminal of the second amplifier A2. The first end of the second capacitor C2 is connected to the output terminal of the second amplifier A2, and the second end of the second capacitor C2 is connected to the inverting input terminal of the second amplifier A2.

[0094] like Figure 6As shown, the mean value amplification submodule 123 includes a third amplifier A3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8. The in-phase input terminal of the third amplifier A3 is connected to the switching submodule 122, the inverting input terminal of the third amplifier A3 is connected to the first end of the eighth resistor R8, and the second end of the eighth resistor R8 is respectively connected to the second end of each third resistor R3. The output terminal of the third amplifier A3 is respectively connected to the in-phase input terminal of each first amplifier A1, the first end of the sixth resistor R6 is connected to the output terminal of the third amplifier A3, the second end of the sixth resistor R6 is connected to the first end of the fifth capacitor C5, the second end of the fifth capacitor C5 is connected to the first end of the fourth capacitor C4, the second end of the fourth capacitor C4 is connected to the first end of the seventh resistor R7, and the second end of the seventh resistor R7 is connected to the second end of the eighth resistor R8. The first end of the sixth capacitor C6 is connected to the output terminal of the third amplifier A3, and the second end of the sixth capacitor C6 is respectively connected to the second end of the fifth capacitor C5 and the inverting input terminal of the third amplifier A3.

[0095] like Figure 7 As shown, the mean value amplification submodule 123 includes a fourth amplifier A4, a seventh capacitor C7, an eighth capacitor C8, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11. The in-phase input terminal of the fourth amplifier A4 is connected to the switching submodule 122, the inverting input terminal of the fourth amplifier A4 is connected to the first end of the eleventh resistor R11, and the second end of the eleventh resistor R11 is respectively connected to the second end of each third resistor R3. The output terminal of the fourth amplifier A4 is respectively connected to the in-phase input terminal of each first amplifier A1, the first end of the ninth resistor R9 is connected to the output terminal of the fourth amplifier A4, the second end of the ninth resistor R9 is connected to the first end of the eighth capacitor C8, the second end of the eighth capacitor C8 is respectively connected to the first end of the seventh capacitor C7 and the inverting input terminal of the fourth amplifier A4, the second end of the seventh capacitor C7 is connected to the first end of the tenth resistor R10, and the second end of the tenth resistor R10 is connected to the second end of the eleventh resistor R11.

[0096] like Figure 8 As shown, the mean amplification submodule 123 includes a fifth amplifier A5, a ninth capacitor C9, a twelfth resistor R12, and a thirteenth resistor R13. The non-inverting input terminal of the fifth amplifier A5 is connected to the switching submodule 122, the inverting input terminal of the fifth amplifier A5 is connected to the first end of the thirteenth resistor R13, and the second end of the thirteenth resistor R13 is respectively connected to the second end of each third resistor R3. The first end of the twelfth resistor R12 is connected to the output terminal of the fifth amplifier A5, the second end of the twelfth resistor R12 is connected to the first end of the ninth capacitor C9, and the second end of the ninth capacitor C9 is connected to the inverting input terminal of the fifth amplifier A5.

[0097] In an embodiment of the present application, the mean amplifier module 123 includes a loop stability compensation unit formed by a combination of resistors and capacitors. While the mean amplifier module 123 obtains the mean error (error signal) of each channel by amplification, the loop stability compensation unit can realize stability correction of the feedback loop, achieving a phase margin greater than 45° and a gain margin greater than 10Db, thereby ensuring that the feedback loop will not self-oscillate and ensuring the stability of the touch detection circuit 10 in processing the touch signal.

[0098] In one possible implementation, the switching submodule 122 transmits a reference voltage signal to the mean amplifying submodule 123. The reference voltage signal is used as a bias to make the error signal output by the mean amplifying submodule 123 a positive signal. Then, based on the error signal, the amplifying submodule 111 can amplify the positive or negative input signal input by the electrode 20 into a positive output signal to facilitate subsequent circuit processing and meet the requirements of a single power supply design for a touch control chip.

[0099] In the self-capacitance mode, a coding signal with a sinusoidal waveform is applied to the driving electrode, and in the mutual capacitance mode, a DC voltage signal is applied to the driving electrode. In order to suppress display interference in the input signal in both the self-capacitance mode and the mutual capacitance mode, and to suppress the basic signal in the self-capacitance mode, the switching submodule 122 needs to transmit different reference voltage signals to the mean amplifier submodule 123 in the self-capacitance mode and the mutual capacitance mode. Specifically, in the mutual capacitance mode, a DC level is transmitted to the mean amplifier submodule 123 as a bias, and in the self-capacitance mode, a coding signal with a sinusoidal waveform is transmitted to the mean amplifier submodule 123 as a bias.

[0100] like Figure 4 As shown, the switching submodule 122 includes a first DC voltage source V1, a first coding unit T1, a first switch S1 and a second switch S2. The output end of the switching submodule 122 is connected to the first end of the first switch S1 and the first end of the second switch S2 respectively, the second end of the first switch S1 is connected to the first DC voltage source V1, and the second end of the second switch S2 is connected to the first coding unit T1.

[0101] In the mutual capacitance mode, the first switch S1 is closed and the second switch S2 is open, and the first DC voltage source V1 transmits a DC voltage (DC level) as a reference voltage signal to the output end of the switching submodule 122 .

[0102] In the self-capacitance mode, the first switch S1 is opened and the second switch S2 is closed, and the first coding unit T1 transmits a self-capacitance coding signal as a reference voltage signal to the output end of the switching submodule 122, wherein the self-capacitance coding signal output by the first coding unit T1 is the same as the coding signal acting on the electrode 20.

[0103] In an embodiment of the present application, the switching submodule 122 includes a first switch S1 and a second switch S2, the first switch S1 is connected to the first DC voltage source V1, and the second switch S2 is connected to the first coding unit T1. In the mutual capacitance mode, the first switch S1 is closed and the second switch S2 is disconnected. The switching submodule 122 transmits the DC level output by the first DC voltage source V1 to the mean amplification submodule 123 as a bias. In the self-capacitance mode, the first switch S1 is disconnected and the second switch S2 is closed. The switching submodule 122 transmits the self-capacitance coding signal output by the first coding unit T1 to the mean amplification submodule 123 as a bias, ensuring that the amplification submodule 111 outputs a positive signal in both the self-capacitance mode and the mutual capacitance mode, which is convenient for post-stage circuit processing, suitable for touch chips with a single power supply design, and improves the applicability of the touch detection circuit 10.

[0104] In one possible implementation, the touch detection circuit 10 also includes multiple processing modules, the output ends of different amplifying sub-modules 111 are connected to different processing modules through the accumulating sub-module 121, and the multiple output ends of the accumulating sub-module 121 are respectively connected to different processing modules, and the output signal of the amplifying sub-module 111 is processed by the accumulating sub-module 121 and then filtered by the corresponding processing module.

[0105] like Figure 4 As shown, the touch detection circuit 10 includes a plurality of processing modules 13 , and the processing module 13 includes a filter 131 , a sample holder 132 and a buffer submodule 133 .

[0106] The output end of the filter 131 is connected to the input end of the sample holder 132, the output end of the sample holder 132 is connected to the input end of the buffer submodule 133, and the output end of the buffer submodule 133 is connected to the input end of the analog-to-digital conversion module 14. The second ends of different third resistors R3 are connected to the input ends of the filters 131 in different processing modules 13. The output ends of the buffer submodules 133 in different processing modules 13 are connected to the input ends of different analog-to-digital conversion modules 14.

[0107] The filter 131 can filter the input signal and remove the reference voltage signal from the input signal to obtain a touch voltage signal. The sample and hold device 132 can sample the touch voltage signal to obtain a target signal and hold the target signal. After the sample and hold device 132 transmits the target signal to the buffer submodule 133, the analog-to-digital conversion module 14 can extract the target signal from the buffer submodule 133. The buffer submodule 133 can ensure that the target signal remains unchanged during the process of the analog-to-digital conversion module 14 extracting the target signal, thereby ensuring that the target signal has sufficient driving capability, so that the analog-to-digital conversion module 14 converts the target signal into a digital signal.

[0108] In the embodiment of the present application, since the switching submodule 122 transmits a reference voltage signal to the mean amplifying submodule 123, the mean amplifying submodule 123 transmits an error signal to the amplifying submodule 111 based on the accumulated current and the reference voltage signal, and the amplifying submodule 111 outputs an output signal according to the error signal and the input signal of the electrode input, and the output signal is converted into an input signal of the filter 131 through the third resistor R3, the input signal of the filter 131 is mixed with the reference voltage signal, and the filter 131 can remove the mixed reference voltage signal in its input signal while filtering its input signal, so that the touch voltage signal output by the filter 131 can accurately indicate the touch state, thereby ensuring the accuracy of touch recognition.

[0109] The analog-to-digital conversion module 14 may not be able to process the touch voltage signal output by the filter 131 in a timely manner. The sample and holder 132 can hold the touch voltage signal. Then, after processing the preceding signal, the analog-to-digital conversion module 14 can process the touch voltage signal held by the sample and holder 132 to ensure that the touch voltage signal output by the filter 131 can be processed by the analog-to-digital conversion module 14, thereby avoiding the problem of touch recognition errors caused by part of the touch voltage signal output by the filter 131 not being processed by the analog-to-digital conversion module 14.

[0110] In a possible implementation, the non-inverting input terminal of each first amplifier A1 is connected to the input terminal of the filter 131 in a processing module 13 .

[0111] The second end of each third resistor R3 is connected to a processing module 13, the second ends of different third resistors R3 are connected to different processing modules 13, and the non-inverting input end of each first amplifier A1 is connected to the same processing module 13, so the total number of processing modules 13 is equal to the number of third resistors R3 plus 1.

[0112] The in-phase input terminal of each first amplifier A1 is connected to the output terminal of the mean amplifier module 123, so the processing module 13 is connected to the output terminal of the mean amplifier module 123, and the error signal output by the mean amplifier module 123 will be transmitted to the processing module 13 connected to the in-phase input terminal of each first amplifier A1, specifically, the error signal will be transmitted to the input terminal of the filter 131. The filter 131 can filter the input error signal, remove the reference voltage signal in the error signal, and then transmit the processed error signal to the connected sample holder 132.

[0113] It should be noted that the processing method of the error signal by the processing module 13 is the same as the processing method of the signal output from the second end of the third resistor R3 , which will not be described in detail here.

[0114] When performing touch recognition, it is necessary to determine the touch position according to the difference (diff) between the touch signals of different channels (digital signals converted from touch voltage signals). When the touch screen or touch pad is touched over a large area, such as when the touch phone is put into a trouser pocket when the screen is unlocked or the alarm is turned off by touching the screen with the palm of the hand, the difference between the touch signals of different channels will be equal to 0, and when the touch screen or touch pad is not touched, the difference between the touch signals of different channels is also equal to 0, which will make it impossible to judge whether the touch screen or touch pad is effectively touched. The output end of the mean amplification submodule 123 is connected to the processing module 13, and the error signal output by the mean amplification submodule 123 is processed and converted into a digital signal by the processing module 13. In the two states of the touch screen or touch pad being touched over a large area and not being touched, the digital signal is different, and then according to the digital signal, it can be judged whether the touch screen or touch pad is effectively touched.

[0115] The amplifying submodule 111 outputs an output signal based on the error signal and the input signal input by the electrode 20. Since the error signal is transmitted to the non-inverting input terminal of the first amplifier A1, this causes the output signal to increase the reference base relative to the input signal. When touch recognition is performed based on the digital signal converted from the touch voltage signal, the software needs to compensate for the diff of different channels based on the reference base of the digital signal. Therefore, the error signal is converted into a corresponding digital signal through the processing module 13. The software can compensate for the digital signal converted from the touch voltage signal based on the digital signal converted from the error signal.

[0116] In an embodiment of the present application, the output end of the mean amplification submodule 123 is connected to a processing module 13, which filters the error signal output by the mean amplification submodule 123 and converts it into a corresponding digital signal. The digital signal can be used as a data reference for software compensation of the diff of each channel to ensure that touch recognition can be carried out normally. Moreover, when the touch screen or touch pad is touched over a large area, it can also be determined based on the digital signal whether the touch screen or touch pad is effectively touched, thereby ensuring the accuracy of touch recognition.

[0117] In one possible implementation, Figure 4 As shown, the filter 131 includes a differential amplifier B, a second DC voltage source V2, a second coding unit T2, a third switch S3, a fourth switch S4, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a tenth capacitor C10, an eleventh capacitor C11 and a twelfth capacitor C12.

[0118] The first end of the fourteenth resistor R14 is connected to the second end of the third resistor R3, and the second end of different third resistors R3 is connected to the first end of different fourteenth resistors R14 in the filter 13. The second end of the fourteenth resistor R14 is connected to the first end of the sixteenth resistor R16, and the second end of the sixteenth resistor R16 is connected to the positive input terminal of the differential amplifier B. The first end of the seventeenth resistor R17 is connected to the first end of the sixteenth resistor R16, and the second end of the seventeenth resistor R17 is connected to the negative output terminal of the differential amplifier B. The first end of the eleventh capacitor C11 is connected to the second end of the sixteenth resistor R16, and the second end of the eleventh capacitor C11 is connected to the negative output terminal of the differential amplifier B.

[0119] The first end of the fifteenth resistor R15 is connected to the first end of the third switch S3 and the first end of the fourth switch S4, respectively. The second end of the third switch S3 is connected to the second DC voltage source V2. The second end of the fourth switch S4 is connected to the second coding unit T2. The second end of the fifteenth resistor R15 is connected to the first end of the eighteenth resistor R18. The second end of the eighteenth resistor R18 is connected to the negative input terminal of the differential amplifier B. The first end of the nineteenth resistor R19 is connected to the first end of the eighteenth resistor R18. The second end of the nineteenth resistor R19 is connected to the positive output terminal of the differential amplifier B. The first end of the twelfth capacitor C12 is connected to the second end of the eighteenth resistor R18. The second end of the twelfth capacitor C12 is connected to the positive output terminal of the differential amplifier B.

[0120] A first end of the tenth capacitor C10 is connected to a first end of the sixteenth resistor R16 , a second end of the tenth capacitor C10 is connected to a first end of the eighteenth resistor R18 , and a positive output end and a negative output end of the differential amplifier B are connected to the sample holder 132 , respectively.

[0121] In mutual capacitance mode, the third switch S3 is closed and the fourth switch S4 is open, and the second DC voltage source V2 outputs a DC voltage that is the same as the reference voltage signal. In self-capacitance mode, the third switch S3 is open and the fourth switch S4 is closed, and the second coding unit T2 outputs a coding signal that is the same as the reference voltage signal.

[0122] In addition to filtering the input signal, the filter 131 also removes the reference voltage signal included in the input signal. Figure 4As shown, in the mutual capacitance mode, the first switch S1 is closed and the second switch S2 is opened, and the first DC voltage source V1 transmits a DC voltage as a reference voltage signal to the output end of the switching submodule 122. At this time, the reference voltage signal included in the input signal of the filter 131 is a DC level. In order to remove the reference voltage signal included in the input signal, the filter 131 closes the third switch S3 and opens the fourth switch S4. The second DC voltage source V2 outputs a DC voltage that is the same as the reference voltage, and then the filter 131 can remove the reference voltage signal included in the input signal according to the DC voltage output by the second DC voltage source V2.

[0123] In the self-capacitive mode, the first switch S1 is disconnected and the second switch S2 is closed, and the first coding unit T1 transmits the self-capacitive coding signal as the reference voltage signal to the output end of the switching submodule 122. At this time, the reference voltage signal included in the input signal of the filter 131 is the self-capacitive coding signal, and the self-capacitive coding signal output by the first coding unit T1 is the same as the coding signal acting on the electrode 20. In order to remove the reference voltage signal included in the input signal, the filter 131 disconnects the third switch S3 and closes the fourth switch S4, and the second coding unit T2 outputs the coding signal that is the same as the reference voltage signal, and then the filter 131 can remove the reference voltage signal included in the input signal according to the coding signal output by the second coding unit T2.

[0124] In an example, the first DC voltage source V1 and the second DC voltage source V2 can output the same DC level, and the first coding unit T1 and the second coding unit T2 can output self-capacitive coding signals having the same phase and amplitude as the coding signal acting on the electrode 20 .

[0125] In the embodiment of the present application, the filter 131 includes a third switch S3 and a fourth switch S4, the third switch S3 is connected to the second DC voltage source V2, and the third switch S4 is connected to the second coding unit T2. In the mutual capacitance mode, the third switch S3 is closed and the fourth switch S4 is disconnected, and the second DC voltage source V2 outputs a DC level identical to the reference voltage signal, so that the filter 131 can remove the reference voltage signal introduced by the first DC voltage source V1. In the self-capacitance mode, the third switch S3 is disconnected and the fourth switch S4 is closed, and the second coding unit T2 outputs a self-capacitance coding signal identical to the reference voltage signal, so that the filter 131 can remove the reference voltage signal introduced by the first coding unit T1, thereby removing the reference voltage signal included in the input signal of the filter 131 in both the mutual capacitance mode and the self-capacitance mode, thereby ensuring the accuracy of touch recognition in the mutual capacitance mode and the self-capacitance mode.

[0126] In one example, the amplification submodule 111 uses Figure 4 In the scheme shown, the accumulation submodule 121 adopts Figure 4In the scheme shown, the mean amplification submodule 123 adopts Figure 5 In the scheme shown, the capacitance value of the first capacitor C1 is 60pF, the resistance value of the first resistor R1 is 1KΩ, the resistance value of the second resistor R2 is 10KΩ, the resistance value of the third resistor R3 is 1KΩ, the capacitance value of the second capacitor C2 is 2pF, the capacitance value of the third capacitor is 100pF, and the resistance value of the fourth resistor R4 is 5KΩ.

[0127] Fig. 9 The phase margin evaluation result of the touch detection circuit in this example is shown. Fig. 9 As shown, when the loading of the touch screen or touch pad is less than or equal to 500pF, the phase margin can be made above 45° by using capacitors with smaller capacitance values ​​and resistors with smaller resistance values ​​to reduce the cost of the touch detection circuit. When the loading of the touch screen or touch pad is less than 500pF, the phase margin is still above 45°, so the touch detection circuit can work stably and normally. Phase margin (PM) refers to the difference (in degrees) between 180° and the phase of the amplifier output signal (relative to its input) when the gain is 0. The industry requires that the phase margin be greater than 45°. If the difference between 180° and the phase of the amplifier output signal is less than 135°, the system will oscillate and fail to work normally.

[0128] Fig.10 The figure shows the suppression effect of the touch detection circuit of the embodiment of the present application on the mutual capacitance coding base. Fig.10 As shown, under the test conditions of the first amplifier A1 with a maximum cutoff frequency GBW = 10MHz, a maximum slew rate SR = 20V / μs, an open-loop gain of 120dB, a main node at 10Hz, and a second pole at 100MHz, the mutual capacitance coding base can be basically suppressed, and the mutual capacitance coding base remains 0.4mVpp under 10Vpp input electrode (TX) coding, which basically does not occupy the dynamic range of the amplifier module 111. When the first capacitor C1 is 500pF and the coding is performed at 10Vpp, the mutual capacitance coding base remains 20mVpp, and the suppression efficiency is about 0.4 / 20 / 20 = 99.9%.

[0129] Fig.11 The figure shows the effect of suppressing display interference by the touch detection circuit of the embodiment of the present application. Fig.11As shown, under the test conditions of the maximum cutoff frequency GBW of the first amplifier A1 = 10MHz, the maximum slew rate SR = 20V / μs, the open-loop gain of 120dB, the main node at 10Hz, and the second pole at 100MHz, the display interference can be basically suppressed, and under the 1Vpp display interference input, the display interference in the output signal of the amplifier module 111 remains 4mVpp, and basically does not occupy the dynamic range of the amplifier module 111. When the first capacitor C1 is 500pF and the display interference input is 1Vpp, the display interference in the output signal of the amplifier module 111 remains 4mVpp, and the suppression efficiency is about 0.4 / 1 / 20=99.8%.

[0130] Fig.10 and Fig.11 The simulation and prototype platform test results are shown. By suppressing the mutual capacitance coding base and display interference, that is, obtaining the average of the coding base and display interference of each sensing electrode channel, the corresponding subtraction is performed. Since the coding base and display interference between channels are relatively small, the coding base and display interference of each channel are basically close to the average value, so the residual amount of coding base and display interference after subtraction is small, and it can be suppressed to less than 1mVpp in actual measurement.

[0131] Fig.12 and Fig.13 The mutual capacitance touch change (touchdiff) effect of the touch detection circuit of the embodiment of the present application is shown, wherein: Fig.12 The mutual capacitance touch diff effect is shown when one of the five channels is touched. Fig.13 Figure 2 shows the mutual capacitance touch diff effect when 2 of the 5 channels are touched. Fig.12 As shown in the figure, when a single channel is touched, the diff of the channel is 10mVpp, and the diff of other channels is 2mVpp. After compensating the mean base (error signal), the diff of the channel is actually 12mVpp. Fig.13 As shown in the figure, when two channels are touched, the diff of these two channels is 8mVpp, and the diff of other channels is 4mVpp. After the mean base is compensated, the actual diff of these two channels is 12mVpp. Fig.12 and Fig.13It can be seen that the touch detection circuit can normally amplify the signal during touch, and the mutual capacitance diff is about 12mVpp. Since there is no loss in diff, after the coding base and display interference are suppressed, the noise in the touch signal is reduced, and the SNR can be significantly improved. The diff is obtained by compensating the mean channel according to the touched channel and the untouched channel. For example, channel 0 of the 6 channels is touched, the diff of channel 0 is 10mV, the mean channel output is 2mV, the diff of channel 0 after compensation is 12mV, and the mean channel output is 12mV / 6=2mV.

[0132] Fig.14 and Fig.15 The figure shows the touchdiff effect of the touch detection circuit of the embodiment of the present application. Fig.14 In the figure, the ordinate V1 represents the input signal of the non-inverting input terminal of the first amplifier A1 in the amplifier module 111, and the ordinate represents the input signal of the inverting input terminal of the first amplifier A1 in the amplifier module 111. According to the virtual short control of the operational amplifier, V1 and V2 are the same. Since the non-inverting input terminal of the first amplifier A1 is connected to the output terminal of the mean amplifier module 123, V1 and V2 can also identify the output signal of the mean amplifier module 123, that is, the mean value of each channel signal.

[0133] like Fig.14 As shown, when there is no touch, the output of the amplifier submodule 111 of each channel in the five channels includes the output electrode (TX) base, such as Fig.14 TX=2Vpp. Fig.15 As shown in FIG. 1 , when one of the five channels is touched, the diff is approximately 1 mVpp, wherein the first capacitor C1 = 300 pF, the self-capacitance change is 0.35 pF, the output electrode base is 2 Vpp, and the coding frequency is 100 KHz. Fig.14 and Fig.15 It can be seen that the touch detection circuit can normally amplify the touch signal, and the diff of the self-capacitance is about 1mVpp. Fig.14 and Fig.15 The actual measurement results of the touch detection circuit provided in the embodiment of the present application show that there is no loss in the diff of the self-capacitance. By suppressing the coding base and display interference, the amplification factor is increased while the display interference is reduced, thereby improving the SNR.

[0134] Touch chip

[0135] An embodiment of the present application provides a touch chip, which includes the touch detection circuit 10 in any of the above embodiments, that is, the touch detection circuit 10 in the above embodiments is packaged in a chip, and the touch chip can be arranged in an electronic device including a touch screen or a touch pad for touch recognition.

[0136] It should be noted that the touch chip in the embodiment of the present application is based on the same concept as the aforementioned touch detection circuit embodiment. The specific contents and beneficial effects can be found in the description of the aforementioned touch detection circuit embodiment, which will not be repeated here.

[0137] Screen module

[0138] Fig.16 Schematic diagram of a screen module according to an embodiment of the present application. Fig.16 As shown, the screen module 160 includes the touch chip 161 and a plurality of electrodes 20 in the above embodiments, and the touch chip 161 includes the touch detection circuit 10 in any of the above embodiments.

[0139] The electrode 20 can receive the touch driving signal output by the touch chip 161, so that the screen module 160 can recognize the touch command. The electrode 20 can be a horizontal electrode and / or a vertical electrode arranged on the touch screen.

[0140] It should be noted that the screen module in the embodiment of the present application is implemented based on the touch detection circuit 10 and the touch chip in the aforementioned embodiment. It is a specific application of the touch detection circuit 10 and the touch chip in the aforementioned embodiment. The specific content and beneficial effects can be found in the description in the aforementioned touch detection circuit embodiment, which will not be repeated here.

[0141] It should be understood that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the method described in the device and system embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of other embodiments.

[0142] It should be understood that the above is a description of a specific embodiment of the present specification. Other embodiments are within the scope of the claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0143] It should be understood that an element described in singular form herein or shown in the drawings as only one does not limit the number of the element to one. In addition, modules or elements described or shown as separate herein may be combined into a single module or element, and modules or elements described or shown as single herein may be split into multiple modules or elements.

[0144] It should also be understood that the terms and expressions used herein are for description only, and one or more embodiments of this specification should not be limited to these terms and expressions. The use of these terms and expressions does not mean to exclude any equivalent features of the illustrations and descriptions (or parts thereof), and it should be recognized that various modifications that may exist should also be included in the scope of the claims. Other modifications, changes and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

Claims

1. A touch detection circuit, characterized in that: The touch detection circuit is connected to a plurality of electrodes; The touch detection circuit is used to process the input signals input by the multiple electrodes to obtain a touch signal corresponding to each of the electrodes, wherein the touch signal is used to indicate the touch state of the touch area where the electrode is located; When the finger is not touching, the touch signal corresponding to the electrode is a first touch signal; when the finger is touching, the touch signal corresponding to the electrode located in the touch area touched by the finger is a second touch signal, and the touch signal corresponding to the electrode located in the touch area not touched by the finger is a third touch signal, and both the second touch signal and the third touch signal are different from the first touch signal.

2. The touch detection circuit according to claim 1, characterized in that: The signal amount of the second touch signal is negatively correlated with the number of the electrodes located in the touch area touched by the finger, and the signal amount of the third touch signal is positively correlated with the number of the electrodes located in the touch area touched by the finger.

3. The touch detection circuit according to claim 1, characterized in that: When different numbers of the electrodes are located in the touch area touched by the finger, the sum of the signal amounts of the second touch signal and the third touch signal is the same.

4. The touch detection circuit according to claim 1, characterized in that: The touch detection circuit includes an analog-to-digital conversion module, and the touch signal is output by the analog-to-digital conversion module.

5. The touch detection circuit according to claim 4, characterized in that: The touch detection circuit includes an amplification module and a feedback module; The amplification module includes a plurality of amplification submodules, and different amplification submodules are connected to different electrodes; The feedback module is used to generate an error signal according to the output signal output by each of the amplifying submodules, and transmit the error signal to each of the amplifying submodules respectively, wherein the error signal is used to indicate the average strength of the interference signal coupled by each of the electrodes; The amplifying submodule is used to output the output signal according to the input signal input by the electrode connected to the amplifying submodule and the error signal, wherein the output signal is used to generate the touch signal corresponding to the electrode connected to the amplifying submodule.

6. The touch detection circuit according to claim 5, characterized in that: The feedback module includes an accumulation submodule, a switching submodule and a mean amplification submodule; The multiple input ends of the accumulation submodule are respectively connected to the amplification submodules; The two input ends of the mean value amplifying submodule are respectively connected to the accumulating submodule and the switching submodule, and the output end of the mean value amplifying submodule is respectively connected to the input end of each amplifying submodule; The accumulation submodule is used to obtain an accumulated current according to the output signal of each of the amplification submodules, and transmit the accumulated current to the mean amplification submodule, wherein the accumulated current is used to indicate the total strength of the interference signal coupled to each of the electrodes; The switching submodule is used to transmit a reference voltage signal to the mean value amplification submodule; The mean value amplifying submodule is used to generate the error signal according to the accumulated current and the reference voltage signal, and transmit the error signal to each of the amplifying submodules respectively.

7. The touch detection circuit according to claim 6, characterized in that: The amplifying submodule includes a first amplifier, a first resistor, a second resistor and a first capacitor; A first end of the first resistor is connected to the electrode, and a second end of the first resistor is connected to an inverting input end of the first amplifier; A first end of the second resistor is connected to an inverting input end of the first amplifier, and a second end of the second resistor is connected to an output end of the first amplifier; A first end of the first capacitor is connected to an inverting input end of the first amplifier, and a second end of the first capacitor is connected to an output end of the first amplifier; The in-phase input terminal of the first amplifier is connected to the mean amplification submodule, the output terminal of the first amplifier is connected to the accumulation submodule, the first amplifier transmits the output signal to the accumulation submodule through the output terminal, and the mean amplification submodule transmits the error signal to the in-phase input terminal of the first amplifier.

8. The touch detection circuit according to claim 7, characterized in that: The accumulation submodule includes a plurality of third resistors; The first end of the third resistor is connected to the output end of the first amplifier, and the second end of the third resistor is connected to the input end of the mean amplification submodule. The first ends of different third resistors are connected to different first amplifiers, and the second ends of different third resistors are connected to the same input end of the mean amplification submodule.

9. The touch detection circuit according to claim 8, characterized in that: The mean value amplification submodule includes: a second amplifier, a second capacitor, a third capacitor, a fourth resistor and a fifth resistor; The non-inverting input terminal of the second amplifier is connected to the switching submodule, the inverting input terminal of the second amplifier is connected to the first end of the fifth resistor, and the second end of the fifth resistor is respectively connected to the second end of each of the third resistors; The output end of the second amplifier is connected to the non-inverting input end of each of the first amplifiers respectively, the first end of the fourth resistor is connected to the output end of the second amplifier, the second end of the fourth resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is connected to the inverting input end of the second amplifier; A first end of the second capacitor is connected to an output end of the second amplifier, and a second end of the second capacitor is connected to an inverting input end of the second amplifier.

10. The touch detection circuit according to claim 8, characterized in that: The mean value amplification submodule includes: a third amplifier, a fourth capacitor, a fifth capacitor, a sixth capacitor, a sixth resistor, a seventh resistor and an eighth resistor; The non-inverting input terminal of the third amplifier is connected to the switching submodule, the inverting input terminal of the third amplifier is connected to the first end of the eighth resistor, and the second end of the eighth resistor is respectively connected to the second end of each of the third resistors; The output end of the third amplifier is connected to the non-inverting input end of each of the first amplifiers respectively, the first end of the sixth resistor is connected to the output end of the third amplifier, the second end of the sixth resistor is connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the first end of the fourth capacitor, the second end of the fourth capacitor is connected to the first end of the seventh resistor, and the second end of the seventh resistor is connected to the second end of the eighth resistor; The first end of the sixth capacitor is connected to the output end of the third amplifier, and the second end of the sixth capacitor is connected to the second end of the fifth capacitor and the inverting input end of the third amplifier respectively.

11. The touch detection circuit according to claim 8, characterized in that: The mean value amplification submodule includes: a fourth amplifier, a seventh capacitor, an eighth capacitor, a ninth resistor, a tenth resistor and an eleventh resistor; The non-inverting input terminal of the fourth amplifier is connected to the switching submodule, the inverting input terminal of the fourth amplifier is connected to the first end of the eleventh resistor, and the second end of the eleventh resistor is respectively connected to the second end of each of the third resistors; The output end of the fourth amplifier is respectively connected to the in-phase input end of each of the first amplifiers, the first end of the ninth resistor is connected to the output end of the fourth amplifier, the second end of the ninth resistor is connected to the first end of the eighth capacitor, the second end of the eighth capacitor is respectively connected to the first end of the seventh capacitor and the inverting input end of the fourth amplifier, the second end of the seventh capacitor is connected to the first end of the tenth resistor, and the second end of the tenth resistor is connected to the second end of the eleventh resistor.

12. The touch detection circuit according to claim 8, characterized in that: The mean value amplification submodule includes: a fifth amplifier, a ninth capacitor, a twelfth resistor and a thirteenth resistor; The non-inverting input terminal of the fifth amplifier is connected to the switching submodule, the inverting input terminal of the fifth amplifier is connected to the first end of the thirteenth resistor, and the second end of the thirteenth resistor is respectively connected to the second end of each of the third resistors; The first end of the twelfth resistor is connected to the output end of the fifth amplifier, the second end of the twelfth resistor is connected to the first end of the ninth capacitor, and the second end of the ninth capacitor is connected to the inverting input end of the fifth amplifier.

13. The touch detection circuit according to any one of claims 9 to 12, characterized in that: The switching submodule includes: a first DC voltage source, a first coding unit, a first switch and a second switch; The output end of the switching submodule is connected to the first end of the first switch and the first end of the second switch respectively, the second end of the first switch is connected to the first DC voltage source, and the second end of the second switch is connected to the first coding unit; In the mutual capacitance mode, the first switch is closed and the second switch is open, and the first DC voltage source transmits a DC voltage to the output end of the switching submodule as the reference voltage signal; In the self-capacitance mode, the first switch is opened and the second switch is closed, and the first coding unit transmits a self-capacitance coding signal to the output end of the switching submodule as the reference voltage signal, wherein the self-capacitance coding signal output by the first coding unit is the same as the coding signal acting on the electrode.

14. The touch detection circuit according to claim 8, characterized in that: The touch detection circuit further includes a plurality of processing modules, each of which includes a filter, a sample holder, and a buffer submodule; The output end of the filter is connected to the input end of the sample holder, the output end of the sample holder is connected to the input end of the buffer submodule, the output end of the buffer submodule is connected to the input end of the analog-to-digital conversion module, wherein the second ends of different third resistors are connected to the input ends of the filters in different processing modules, and the output ends of the buffer submodules in different processing modules are connected to the input ends of different analog-to-digital conversion modules; The filter is used to filter the input signal and remove the reference voltage signal included in the input signal to obtain a touch voltage signal; The sample-and-hold device is used to sample the touch voltage signal to obtain a target signal, and to hold the target signal; The buffer submodule is used to transmit the target signal unchanged to the analog-to-digital conversion module, so that the analog-to-digital conversion module converts the target signal into the touch signal.

15. The touch detection circuit according to claim 14, characterized in that: The non-inverting input terminal of each of the first amplifiers is connected to the input terminal of the filter in one of the processing modules.

16. The touch detection circuit according to claim 14 or 15, characterized in that: The filter comprises: a differential amplifier, a second DC voltage source, a second coding unit, a third switch, a fourth switch, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a tenth capacitor, an eleventh capacitor and a twelfth capacitor; The first end of the fourteenth resistor is connected to the second end of the third resistor, wherein the second ends of different third resistors are connected to the first ends of the fourteenth resistors in different filters; The second end of the fourteenth resistor is connected to the first end of the sixteenth resistor, the second end of the sixteenth resistor is connected to the positive input terminal of the differential amplifier, the first end of the seventeenth resistor is connected to the first end of the sixteenth resistor, the second end of the seventeenth resistor is connected to the negative output terminal of the differential amplifier, the first end of the eleventh capacitor is connected to the second end of the sixteenth resistor, and the second end of the eleventh capacitor is connected to the negative output terminal of the differential amplifier; The first end of the fifteenth resistor is connected to the first end of the third switch and the first end of the fourth switch respectively, the second end of the third switch is connected to the second DC voltage source, and the second end of the fourth switch is connected to the second coding unit; The second end of the fifteenth resistor is connected to the first end of the eighteenth resistor, the second end of the eighteenth resistor is connected to the negative input terminal of the differential amplifier, the first end of the nineteenth resistor is connected to the first end of the eighteenth resistor, the second end of the nineteenth resistor is connected to the positive output terminal of the differential amplifier, the first end of the twelfth capacitor is connected to the second end of the eighteenth resistor, and the second end of the twelfth capacitor is connected to the positive output terminal of the differential amplifier; The first end of the tenth capacitor is connected to the first end of the sixteenth resistor, the second end of the tenth capacitor is connected to the first end of the eighteenth resistor, and the positive output end and the negative output end of the differential amplifier are respectively connected to the sample holder; In the mutual capacitance mode, the third switch is closed and the fourth switch is open, and the second DC voltage source outputs a DC voltage that is the same as the reference voltage signal; In the self-capacitive mode, the third switch is opened and the fourth switch is closed, and the second coding unit outputs a coding signal that is the same as the reference voltage signal.

17. A touch chip, characterized in that: The touch detection circuit comprises any one of claims 1-16.

18. A screen module, characterized in that: include: A plurality of electrodes and a touch control chip as claimed in claim 17; The electrodes are used to receive the touch driving signal output by the touch chip so that the screen module recognizes the touch command, wherein the electrodes are horizontal electrodes and / or vertical electrodes arranged on the touch screen.

Images