Touch detection circuit, touch chip and screen module

Abstract

The embodiment of the invention 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] Embodiments of the present application relate to the field of electronic technologies, and in particular, to a touch detection circuit, a touch chip, and a screen module. Background Art

[0002] With the increase in the size of the screen and the progress of screen manufacturing technology, the coupling between the screen touch sensor and display interference has become increasingly serious. The display interference coupled to the screen touch sensor increases, resulting in a decrease in the signal-to-noise ratio (SNR) of the touch signal obtained by the screen touch sensor. As a result, when performing touch recognition through the touch signal, the accuracy of touch recognition is relatively low.

[0003] Currently, the effective touch signal in the touch signal is recognized by amplifying the touch signal.

[0004] However, since the display interference coupled to the screen touch sensor is relatively large, 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 relatively small, and thus the accuracy of touch detection based on the effective touch signal is still relatively low. Summary of the Invention

[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 the embodiments of the present application, a touch detection circuit is provided. The touch detection circuit is connected to a plurality of electrodes. The touch detection circuit is configured to process input signals input by the plurality of electrodes to obtain a touch signal corresponding to each electrode, where the touch signal is used to indicate a touch state of a touch area where the electrode is located. When a finger does not touch, the touch signal corresponding to the electrode is a first touch signal. When a finger touches, the touch signal corresponding to the electrode located in the touched touch area is a second touch signal, and the touch signal corresponding to the electrode located in the non-touched touch area is a third touch signal. The second touch signal and the third touch signal are both 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 electrodes located in the touched touch area, and the signal amount of the third touch signal is positively correlated with the number of electrodes located in the touched touch area.

[0008] In a possible implementation, when different numbers of the electrodes are located in the touch area touched by a 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 a plurality of amplification sub-modules, and different ones of the amplification sub-modules are connected to different ones of the electrodes; the feedback module is configured to generate an error signal according to the output signals output by the respective amplification sub-modules, and transmit the error signal to the respective amplification sub-modules, wherein the error signal is used to indicate the average intensity of the interference signals coupled by the respective electrodes; the amplification sub-module is configured 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 sub-module, a switching sub-module, and an average value amplification sub-module; a plurality of input ends of the accumulation sub-module are respectively connected to the respective amplification sub-modules; two input ends of the average value amplification sub-module are respectively connected to the accumulation sub-module and the switching sub-module, and an output end of the average value amplification sub-module is respectively connected to input ends of the respective amplification sub-modules; the accumulation sub-module is configured to obtain an accumulation current according to the output signals of the respective amplification sub-modules, and transmit the accumulation current to the average value amplification sub-module, wherein the accumulation current is used to indicate the total intensity of the interference signals coupled by the respective electrodes; the switching sub-module is configured to transmit a reference voltage signal to the average value amplification sub-module; the average value amplification sub-module is configured to generate the error signal according to the accumulation current and the reference voltage signal, and transmit the error signal to the respective amplification sub-modules.

[0012] In a possible implementation, the amplification sub-module 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 terminal of the first amplifier; a first end of the second resistor is connected to the inverting input terminal of the first amplifier, and a second end of the second resistor is connected to an output terminal of the first amplifier; a first end of the first capacitor is connected to the inverting input terminal of the first amplifier, and a second end of the first capacitor is connected to the output terminal of the first amplifier; a non-inverting input terminal of the first amplifier is connected to the mean amplification sub-module, and an output terminal of the first amplifier is connected to the accumulation sub-module. The first amplifier transmits the output signal to the accumulation sub-module through the output terminal, and the mean amplification sub-module transmits the error signal to the non-inverting input terminal of the first amplifier.

[0013] In a possible implementation, the accumulation sub-module includes a plurality of third resistors; a first end of the third resistor is connected to the output terminal of the first amplifier, and a second end of the third resistor is connected to an input terminal of the mean amplification sub-module. 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 terminal of the mean amplification sub-module.

[0014] In a possible implementation, the mean amplification sub-module includes: a second amplifier, a second capacitor, a third capacitor, a fourth resistor, and a fifth resistor; a non-inverting input terminal of the second amplifier is connected to the switching sub-module, an inverting input terminal of the second amplifier is connected to a first end of the fifth resistor, and a second end of the fifth resistor is respectively connected to the second ends of the third resistors; an output terminal of the second amplifier is respectively connected to the non-inverting input terminals of the first amplifiers, a first end of the fourth resistor is connected to the output terminal of the second amplifier, a second end of the fourth resistor is connected to a first end of the third capacitor, and a second end of the third capacitor is connected to the inverting input terminal of the second amplifier; a first end of the second capacitor is connected to the output terminal of the second amplifier, and a 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 sub-module 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 sub-module, 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 ends of the third resistors; the output terminal of the third amplifier is respectively connected to the non-inverting input terminals 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 sub-module 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 sub-module, 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 ends of the third resistors; the output terminal of the fourth amplifier is respectively connected to the non-inverting input terminals of the first amplifiers, the first end of the ninth resistor is connected to the output terminal 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 sub-module 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 sub-module, 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 ends 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 sub-module includes: a first DC voltage source, a first coding unit, a first switch, and a second switch; the output end of the switching sub-module 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 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 sub-module as the reference voltage signal; in the self-capacitance mode, the first switch is open and the second switch is closed, and the first coding unit transmits a self-capacitance coding signal to the output end of the switching sub-module as the reference voltage signal, where 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 further includes a plurality of processing modules, and each processing module includes a filter, a sample and hold circuit, and a buffer sub-module; the output end of the filter is connected to the input end of the sample and hold circuit, the output end of the sample and hold circuit is connected to the input end of the buffer sub-module, and the output end of the buffer sub-module is connected to the input end of the analog-to-digital conversion module, where 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 sub-modules in different processing modules are connected to the input ends of different analog-to-digital conversion modules; the filter is configured 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 circuit is configured to sample the touch voltage signal to obtain a target signal and hold the target signal; the buffer sub-module is configured 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, the non-inverting input ends of the first amplifiers are connected to the input ends of the filters 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; a first end of the fourteenth resistor is connected to a 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; a second end of the fourteenth resistor is connected to a first end of the sixteenth resistor, a second end of the sixteenth resistor is connected to a positive input terminal of the differential amplifier, a first end of the seventeenth resistor is connected to the first end of the sixteenth resistor, a second end of the seventeenth resistor is connected to a negative output terminal of the differential amplifier, a first end of the eleventh capacitor is connected to the second end of the sixteenth resistor, and a second end of the eleventh capacitor is connected to the negative output terminal of the differential amplifier; a first end of the fifteenth resistor is respectively connected to a first end of the third switch and a first end of the fourth switch, a second end of the third switch is connected to the second DC voltage source, and a second end of the fourth switch is connected to the second coding unit; a second end of the fifteenth resistor is connected to a first end of the eighteenth resistor, a second end of the eighteenth resistor is connected to a negative input terminal of the differential amplifier, a first end of the nineteenth resistor is connected to the first end of the eighteenth resistor, a second end of the nineteenth resistor is connected to a positive output terminal of the differential amplifier, a first end of the twelfth capacitor is connected to the second end of the eighteenth resistor, and a second end of the twelfth capacitor is connected to the positive output terminal of the differential amplifier; a first end of the tenth capacitor is connected to the first end of the sixteenth resistor, a 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 circuit; 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 identical to the reference voltage signal; in the self-capacitance mode, the third switch is open 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 the embodiments of the present application, there is provided a touch chip including the touch detection circuit described in the first aspect above.

[0023] According to a third aspect of the embodiments of the present application, there is provided a screen module including: a plurality of electrodes and the touch chip described in the second aspect above; the electrodes are configured to receive a touch driving signal output by the touch chip to enable the screen module to recognize a touch command, 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, after the touch detection circuit sums up the output signals of each electrode, it can suppress the display interference and the basic signal by means of pre-stage feedback mean error, so that the effective touch signal has a large dynamic range and the accuracy of touch recognition is improved. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained according to 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 still 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 is a schematic diagram of the circuit structure of a mean amplification sub-module provided by an embodiment of the present application;

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

[0032] Figure 7 is a schematic diagram of the circuit structure of a mean amplification sub-module according to still another embodiment of the present application;

[0033] Figure 8 is a schematic diagram of the circuit structure of a mean amplification sub-module according to yet another embodiment of the present application;

[0034] Figure 9 is a schematic diagram of the phase margin evaluation result according to an embodiment of the present application;

[0035] Figure 10 is a schematic diagram of the mutual capacitance coding base suppression effect according to an embodiment of the present application;

[0036] Figure 11 is a schematic diagram of the display interference suppression effect according to an embodiment of the present application;

[0037] Figure 12Schematic diagram of the mutual capacitance touch diff effect in an embodiment of the present application;

[0038] Figure 13 Schematic diagram of the mutual capacitance touch diff effect in another embodiment of the present application;

[0039] Figure 14 Schematic diagram of the self - capacitance touch diff effect in an embodiment of the present application;

[0040] Figure 15 Schematic diagram of the self - capacitance touch diff effect in another embodiment of the present application;

[0041] Figure 16 Schematic diagram of a screen module in an embodiment of the present application. Detailed implementation manners

[0042] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art shall fall within the scope of protection of the embodiments of the present application.

[0043] The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. 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 of the 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, such 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 "when" or "while" or "in response to a determination".

[0045] Touch detection circuit

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

[0047] Define the touch signal corresponding to the electrode when the finger is not touching as the first touch signal. Define the touch signal corresponding to the electrode in the touch area touched by the finger when the finger is touching as the second touch signal, and define the touch signal corresponding to the electrode in the touch area not touched by the finger when the finger is touching as the third touch signal. The first touch signal, the second touch signal, and the third touch signal satisfy the following conditions: both the second touch signal and the third touch signal are different from the first touch signal.

[0048] The electrodes 20 on the touch screen can include the arranged horizontal electrodes and vertical electrodes. When a finger touches the touch screen, it will change the coupling capacitance of the electrodes in the touch area touched by the finger, and further change the touch signals corresponding to the electrodes. According to the touch signals corresponding to each electrode, the touch position of the finger on the touch screen can be determined to achieve 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. Furthermore, the touch area of the finger on the touch screen can be determined according to the touch area on the touch screen where the electrode corresponding to the second touch signal is located.

[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 the 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 at this time the touch change amount is equal to 0. When the finger is touching, 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 amounts corresponding to the electrodes in the touch area touched by the finger and the touch area not touched by the finger are different. Furthermore, the touch area of the finger can be determined according to the touch change amounts corresponding to each electrode.

[0051] The electrode 20 may include horizontal electrodes and vertical electrodes arranged on the touch screen, and the horizontal electrodes and the vertical electrodes are arranged perpendicular to each other. For a capacitive touch screen, when performing touch recognition, a self-capacitance mode, a mutual-capacitance mode, or a combined self-mutual capacitance mode may be adopted for touch recognition. In the self-capacitance mode, a touch signal is generated based on the change in the capacitance value of the driving electrode with respect to the ground capacitance. In the mutual-capacitance mode, a touch signal is generated based on the change in the capacitance value between the driving electrode and the sensing electrode. The electrode 20 will couple display interference, and in the self-capacitance mode, even when there is no finger touch, the electrode will also generate a base signal (encoding base) due to the ground capacitance (or coupling capacitance) existing in itself. Therefore, the output signal of the electrode 20 during touch includes display interference, a base signal, and a valid touch signal. The valid touch signal is used for touch recognition. Compared with the valid touch signal, the display interference and the base signal are interference signals.

[0052] During encoding, the base signal and the display interference will occupy the dynamic range. The main purpose of this solution is to eliminate or reduce the influence of the base signal and the display interference on the dynamic range, so as to only amplify the valid touch signal during touch, thereby obtaining a larger SNR.

[0053] The display interference coupled to different electrodes 20 is basically the same, and the base signals on different electrodes 20 are also basically the same.

[0054] In the self-capacitance mode, the electrode 20 includes each horizontal electrode and vertical electrode on the touch screen. In the mutual-capacitance mode, the electrode 20 includes each sensing electrode 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 the base signal in the signals 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. After feedback of the mean error, the touch signals corresponding to each electrode 20 are still consistent, that is, when the finger does not touch, the touch signals corresponding to each electrode 20 are all the first touch signals. When the finger touches the touch screen, the output signals output by the electrodes 20 in the touch area touched by the finger are different from the output signals output by the electrodes 20 in the touch area not touched by the finger. After feedback of the mean error, the touch signals corresponding to the electrodes 20 in the touched and non-touched touch areas are all changed relative to the first touch signal, so that the touch signal corresponding to the electrode 20 in the touched touch area is the second touch signal, and the touch signal corresponding to the electrode 20 in the non-touched touch area is the third touch signal, and the second touch signal is different from the third touch signal.

[0056] In an embodiment of the present application, after the touch detection circuit 10 sums up the output signals of each electrode 20, the display interference and the base signal can be suppressed by means of pre-stage feedback mean error, so that the effective touch signal has a large dynamic range and the accuracy of touch recognition is improved.

[0057] In a possible implementation manner, 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.

[0058] When suppressing the display interference and the base signal by means of pre-stage feedback mean error, 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, while 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. Therefore, 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.

[0059] When the 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. Therefore, 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, which ensures that the display interference and the base signal can be effectively suppressed both when the touch screen is touched in a small area and in a large area, and the accuracy of touch recognition is improved.

[0061] In a possible implementation manner, 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 in the touched touch area is equal to the difference between the pre-suppression touch signal and the mean error, that is, the second touch signal is equal to the difference between the pre-suppression touch signal of the corresponding electrode 20 and the mean error. The touch signal corresponding to the electrode 20 in the untouched touch area is equal to the sum of the pre-suppression touch signal and the mean error, that is, the third touch signal is equal to the sum of the pre-suppression touch signal of the corresponding electrode 20 and the mean error. When a finger touches, the pre-suppression touch signal corresponding to the electrode 20 in the untouched touch area is equal to 0, so the third touch signal is equal to the mean error. Furthermore, the sum of the second touch signal and the third touch signal is equal to the pre-suppression touch signal corresponding to the electrode 20 in the touched touch area. Since the pre-suppression touch signal corresponding to the electrode 20 in the touched touch area is a fixed value, the sum of the second touch signal and the third touch signal has nothing to do with the number of electrodes 20 in the touched touch area. The sum of the signal amounts of the second touch signal and the third touch signal is always equal to the pre-suppression touch signal corresponding to the electrode 20 in the touched touch area.

[0063] In one example, the second touch signal The third touch signal The mean error is equal to V 0 represents the pre-suppression touch signal of the electrode 20 in the touched touch area, N represents the number of electrodes 20, and n represents the number of electrodes 20 in the touched touch area. It can be seen that V 2 +V 3 =V 0 , which has nothing to do with the number of electrodes 20 in the touched touch area.

[0064] In the embodiment of the present application, when different numbers of electrodes 20 are in the touched touch area, the sum of the signal amounts of the second touch signal and the third touch signal is equal. Whether it is a small-area touch or a large-area touch of the finger, it can effectively suppress the display interference and the basic signal, so that accurate touch recognition can be performed both in the small-area touch and the large-area touch of the finger, 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 signals corresponding to the respective electrodes 20 can be detected at the output end of the analog-to-digital conversion module.

[0066] In one example, the touch signals corresponding to the respective electrodes 20 can 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. The analog-to-digital conversion module can convert an analog signal into a digital signal, thereby obtaining a touch signal in digital signal form, so that a microcontroller unit (MCU) can determine the finger touch position according to the touch signal in digital signal form.

[0068] Figure 2 is a schematic diagram of a touch detection circuit according to another embodiment of the present application. As Figure 2 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 sub-modules 111, and different amplification sub-modules 111 are connected to different electrodes 20.

[0069] A feedback module 12 is connected to the output ends of a plurality of amplification sub-modules 111. The feedback module 12 can generate an error signal according to the output signals output by the respective amplification sub-modules 111, and transmit the error signal to the respective amplification sub-modules 111. The error signal can indicate the average intensity of the interference signals coupled to the respective electrodes 20. After receiving the input signal and the error signal input by the connected electrode 20, the amplification sub-module 111 can output an output signal according to the received input signal and error signal. The output signal is used to generate a touch signal corresponding to the electrode 20 connected to the amplification sub-module 111.

[0070] In an embodiment of the present application, the amplification sub-module 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 according to the output signals of the respective amplification sub-modules 111, so that the error signal can indicate the average intensity of the interference signals coupled to the respective electrodes 20. Furthermore, after the error signal is fed back to the amplification sub-module 111, the amplification sub-module 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. Furthermore, when performing touch recognition based on the output signal, the accuracy of touch recognition can be improved.

[0071] In a possible implementation manner, the feedback module 12 can accumulate the output signals of the respective amplification sub-modules 111, and then obtain the mean value of the accumulation result as the error signal.

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

[0073] The multiple input ends of the accumulation sub-module 121 are respectively connected to each amplification sub-module 111. The two input ends of the mean value amplification sub-module 123 are respectively connected to the accumulation sub-module 121 and the switching sub-module 122, and the output end of the mean value amplification sub-module 123 is respectively connected to the input ends of each amplification sub-module 111.

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

[0075] The output signal of the amplification sub-module 111 is a voltage signal. The accumulation sub-module 121 can convert the voltage signal into a current signal, and then can accumulate the converted current signals to obtain an accumulated current, so that the accumulated current can indicate the total intensity of the interference signals coupled by each electrode 20.

[0076] Since the touch chip usually uses a single power supply, the switching sub-module 122 transmits a reference voltage signal as a bias to the mean value amplification sub-module 123, so that the mean value amplification sub-module 123 performs averaging and amplification processing according to the reference voltage signal and the accumulated current. The generated error signal is a positive signal, and further makes the output signal of the amplification sub-module 111 also a positive signal, ensuring that the subsequent circuit can process normally.

[0077] The mean value amplification sub-module 123 generates an error signal that can indicate the average intensity of the interference signals coupled by each electrode 20 according to the reference voltage signal and the accumulated current, and makes the error signal a positive signal. Then, after the error signal is respectively fed back to each amplification sub-module 111, the amplification sub-module 111 can suppress the interference signals in the input signal, thereby reducing the interference signals in the output signal of the amplification sub-module 111.

[0078] In the embodiment of the present application, the accumulation sub-module 121 obtains an accumulated current according to the output signals of each amplification sub-module 111, so that the accumulated current can indicate the total intensity of the interference signals coupled by each electrode. After transmitting the accumulated current to the mean value amplification sub-module 123, the mean value amplification sub-module 123 obtains an error signal through amplification, so that the error signal can indicate the average intensity of the interference signals coupled by each electrode 20. Then, after the error signal is respectively fed back to each amplification sub-module 111, the amplification sub-module 111 suppresses the display interference and the basic signal in the input signal, thereby reducing the interference signals included in the output signal of the amplification sub-module 111.

[0079] In a possible implementation, the amplification sub-module 111 can suppress the display interference and the base signal in the input signal in a negative feedback manner.

[0080] Figure 4 is a schematic diagram of a touch detection circuit according to another embodiment of the present application. As Figure 4 shown, the amplification sub-module 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 terminal of the first amplifier A1. The electrodes RX0 to RXn are respectively connected to different amplification sub-modules 111, and the first ends of the first resistors R1 in different amplification sub-modules 111 are connected to different electrodes 20. For example, the electrodes RX0, RX1, and RXn are connected to the first ends of different first resistors R1.

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

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

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

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

[0086] It should be noted that the first amplifier A1 can be a Programmable Gain Amplifier (PGA).

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

[0088] In a possible implementation manner, as Figure 4 shown, the accumulation sub-module 121 includes a plurality of third resistors R3. The first end of the third resistor R3 is connected to the output terminal of the first amplifier A1, and the second end of the third resistor R3 is connected to the input terminal of the mean value amplification sub-module 123. Each of the plurality of third resistors R3 can be respectively matched with each first amplifier A1. The first ends of different third resistors R3 are connected to the output terminals of different first amplifiers A1, and the second ends of different third resistors R3 are connected to the same input terminal of the mean value amplification sub-module 123.

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

[0090] In the embodiment of the present application, the amplification sub-module 111 is implemented as a transimpedance amplifier. The first amplifier A1 outputs a voltage signal, and this voltage signal is converted into a current signal through the third resistor R3. The second ends of all the third resistors R3 are connected to the same input terminal of the mean value amplification sub-module 123, that is, the current input by the accumulation sub-module 121 to the mean value amplification sub-module 123 is the accumulated current of each channel. Since the voltage signal output from the first amplifier A1 includes an interference signal, the current signal converted from this voltage signal through the third resistor R3 also includes an interference signal. Therefore, the accumulated current can indicate the total intensity of the interference signals coupled by each electrode 20. Since the interference signals coupled by different electrodes 20 are basically the same, an error signal for indicating the average intensity of the interference signals coupled by each electrode 20 is determined based on the accumulated current, ensuring that the error signal can accurately reflect the interference signals coupled by the electrode 20.

[0091] In a possible implementation, the mean amplification sub-module 123 obtains the mean error (error signal) of different channels through amplification, and then feeds it back to the amplification sub-module 111 of each channel for suppressing interference and the base signal. As Figure 4 shown, the mean amplification sub-module 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 sub-module 111, the accumulation sub-module 121, the switching sub-module 122, and the mean amplification sub-module 123 can form a feedback loop. The loop stability compensation unit 1232 can achieve the stability compensation of the feedback loop through the combination of resistors and capacitors, so that the phase margin is greater than 45° and the gain margin is greater than 10 Db, thereby ensuring that the feedback loop will not generate self-excited oscillation and ensuring the stability of the touch detection circuit 10 for processing touch signals.

[0092] Since the loop stability compensation unit 1232 can achieve the stability compensation of the feedback loop through the combination of resistors and capacitors, the loop stability compensation unit 1232 has various different forms, and thus the mean amplification sub-module 123 has various circuit structures. Figures 5 to 8 Four circuit structures of the mean amplification sub-module 123 are shown. The possible circuit structures of the mean amplification sub-module 123 will be described below.

[0093] As Figure 5 shown, the mean amplification sub-module 123 includes a second amplifier A2, a second capacitor C2, a third capacitor C3, a fourth resistor R4, and a fifth resistor R5. The non-inverting input terminal of the second amplifier A2 is connected to the switching sub-module 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 ends of the third resistors R3. The output terminal of the second amplifier A2 is respectively connected to the non-inverting input terminals of the first amplifiers 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] As Figure 6As shown, the mean amplification sub-module 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 non-inverting input terminal of the third amplifier A3 is connected to the switching sub-module 122. The inverting input terminal of the third amplifier A3 is connected to the first end of the eighth resistor R8. The second end of the eighth resistor R8 is respectively connected to the second ends of the respective third resistors R3. The output terminal of the third amplifier A3 is respectively connected to the non-inverting input terminals of the respective first amplifiers 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. 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. 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] As Figure 7 shown, the mean amplification sub-module 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 non-inverting input terminal of the fourth amplifier A4 is connected to the switching sub-module 122. The inverting input terminal of the fourth amplifier A4 is connected to the first end of the eleventh resistor R11. The second end of the eleventh resistor R11 is respectively connected to the second ends of the respective third resistors R3. The output terminal of the fourth amplifier A4 is respectively connected to the non-inverting input terminals of the respective first amplifiers 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. The second end of the tenth resistor R10 is connected to the second end of the eleventh resistor R11.

[0096] As Figure 8 shown, the mean amplification sub-module 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 sub-module 122. The inverting input terminal of the fifth amplifier A5 is connected to the first end of the thirteenth resistor R13. The second end of the thirteenth resistor R13 is respectively connected to the second ends of the respective third resistors 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. The second end of the ninth capacitor C9 is connected to the inverting input terminal of the fifth amplifier A5.

[0097] In the embodiment of the present application, the mean amplification sub-module 123 includes a loop stability compensation unit formed by a combination of resistors and capacitors. While the mean amplification sub-module 123 obtains the mean error (error signal) of each channel through amplification, the loop stability compensation unit can achieve the stability correction of the feedback loop, so that the phase margin is greater than 45° and the gain margin is greater than 10 dB, thereby ensuring that the feedback loop will not generate self-excited oscillation and ensuring the stability of the touch detection circuit 10 in processing touch signals.

[0098] In a possible implementation manner, the switching sub-module 122 transmits a reference voltage signal to the mean amplification sub-module 123. The reference voltage signal serves as a bias to make the error signal output by the mean amplification sub-module 123 a positive signal. Furthermore, based on the error signal, the amplification sub-module 111 can amplify the positive and negative input signals input by the electrode 20 into a positive output signal, which is convenient for the subsequent circuit processing and meets the requirements of the single power supply design of the touch chip.

[0099] In the self-capacitance mode, a coded signal with a sine wave 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 be able to suppress the display interference in the input signal in both the self-capacitance mode and the mutual-capacitance mode, and suppress the basic signal in the self-capacitance mode, the switching sub-module 122 needs to transmit different reference voltage signals to the mean amplification sub-module 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 amplification sub-module 123 as a bias, and in the self-capacitance mode, a coded signal with a sine wave waveform is transmitted to the mean amplification sub-module 123 as a bias.

[0100] As Figure 4 shown, the switching sub-module 122 includes a first DC voltage source V1, a first coding unit T1, a first switch S1, and a second switch S2. The output terminal of the switching sub-module 122 is respectively connected to the first terminal of the first switch S1 and the first terminal of the second switch S2. The second terminal of the first switch S1 is connected to the first DC voltage source V1, and the second terminal 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 opened, and the first DC voltage source V1 transmits a DC voltage (DC level) to the output terminal of the switching sub-module 122 as a reference voltage signal.

[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 to the output terminal of the switching sub-module 122 as a reference voltage signal. Among them, the self-capacitance coding signal output by the first coding unit T1 is the same as the coding signal applied to the electrode 20.

[0103] In the embodiment of the present application, the switching sub-module 122 includes a first switch S1 and a second switch S2. The first switch S1 is connected to a first DC voltage source V1, and the second switch S2 is connected to a first coding unit T1. In the mutual capacitance mode, the first switch S1 is closed and the second switch S2 is opened, and the switching sub-module 122 transmits the DC level output by the first DC voltage source V1 to the mean amplification sub-module 123 as a bias. In the self-capacitance mode, the first switch S1 is opened and the second switch S2 is closed, and the switching sub-module 122 transmits the self-capacitance coding signal output by the first coding unit T1 to the mean amplification sub-module 123 as a bias, ensuring that the amplification sub-module 111 outputs a positive signal in both the self-capacitance mode and the mutual capacitance mode, facilitating the processing of the subsequent circuit, being applicable to a touch chip with a single power supply design, and improving the applicability of the touch detection circuit 10.

[0104] In a possible implementation manner, the touch detection circuit 10 further includes a plurality of processing modules. The output ends of different amplification sub-modules 111 are connected to different processing modules through an accumulation sub-module 121. The multiple output ends of the accumulation sub-module 121 are respectively connected to different processing modules. After the output signal of the amplification sub-module 111 is processed by the accumulation sub-module 121, it is filtered by the corresponding processing module.

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

[0106] The output end of the filter 131 is connected to the input end of the sample and hold circuit 132. The output end of the sample and hold circuit 132 is connected to the input end of the buffer sub-module 133. The output end of the buffer sub-module 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 sub-modules 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, remove the reference voltage signal in the input signal, and obtain the touch voltage signal. The sample and hold circuit 132 can sample the touch voltage signal to obtain a target signal and hold the target signal. After the sample and hold circuit 132 transmits the target signal to the buffer sub-module 133, the analog-to-digital conversion module 14 can extract the target signal from the buffer sub-module 133. The buffer sub-module 133 can ensure that the target signal remains unchanged during the process of the analog-to-digital conversion module 14 extracting the target signal, so as to ensure that the target signal has sufficient driving ability and enable the analog-to-digital conversion module 14 to convert the target signal into a digital signal.

[0108] In the embodiment of the present application, since the switching sub-module 122 transmits a reference voltage signal to the mean amplification sub-module 123, the mean amplification sub-module 123 transmits an error signal to the amplification sub-module 111 based on the accumulated current and the reference voltage signal, and the amplification sub-module 111 outputs an output signal according to the error signal and the input signal input by the electrode. The output signal is converted into an input signal of the filter 131 through the third resistor R3. Therefore, the input signal of the filter 131 is mixed with the reference voltage signal. While filtering its input signal, the filter 131 can remove the mixed reference voltage signal in 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 time. The sample and hold circuit 132 can hold the touch voltage signal. Then, after processing the previous signal, the analog-to-digital conversion module 14 can process the touch voltage signal held by the sample and hold circuit 132, ensuring that all the touch voltage signals output by the filter 131 can be processed by the analog-to-digital conversion module 14, and avoiding the problem of touch recognition error caused by some touch voltage signals 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 a filter 131 in a processing module 13.

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

[0112] The non-inverting input terminals of each first amplifier A1 are connected to the output terminal of the mean amplification sub-module 123. Therefore, the processing module 13 is connected to the output terminal of the mean amplification sub-module 123. The error signal output by the mean amplification sub-module 123 will be transmitted to the processing module 13 connected to the non-inverting input terminals 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 and hold circuit 132.

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

[0114] When performing touch recognition, it is necessary to determine the touch position based on the difference (diff) between touch signals of different channels (digital signals converted from touch voltage signals). When the touch screen or touchpad is touched over a large area, such as when the touch phone is put into the pocket in the unlocked state or the touch screen is touched with the palm to turn off the alarm, etc., the difference between the touch signals of different channels will be equal to 0. And when the touch screen or touchpad is not touched, the difference between the touch signals of different channels is also equal to 0, which makes it impossible to determine whether the touch screen or touchpad is effectively touched. Connect the output end of the mean amplification sub-module 123 to the processing module 13. The processing module 13 processes the error signal output by the mean amplification sub-module 123 and converts it into a digital signal. In the two states of the touch screen or touchpad being touched over a large area and not being touched, this digital signal is different. Thus, it can be determined whether the touch screen or touchpad is effectively touched based on this digital signal.

[0115] The amplification sub-module 111 outputs an output signal according to the error signal and the input signal input from 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 be raised by the reference base (base) relative to the input signal. When performing touch recognition based on the digital signal converted from the touch voltage signal, the software needs to perform a compensation operation on the diff of different channels based on the reference base of this digital signal. Therefore, the error signal is converted into a corresponding digital signal by the processing module 13, and the software can perform a compensation operation on the digital signal converted from the touch voltage signal according to the digital signal converted from the error signal.

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

[0117] In a possible implementation manner, as Figure 4 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 ends of different third resistors R3 are connected to the first ends of the fourteenth resistor R14 in different filters 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 respectively connected to the first ends of the third switch S3 and the fourth switch S4. The second end of the third switch S3 is connected to the second DC voltage source V2, and 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, and 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, and 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, and the second end of the twelfth capacitor C12 is connected to the positive output terminal of the differential amplifier B.

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

[0121] In the 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 identical to the reference voltage signal. In the 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 identical to the reference voltage signal.

[0122] The filter 131 not only filters the input but also removes the reference voltage signal included in the input signal. For example Figure 4As shown, in the mutual capacitance mode, the first switch S1 is closed and the second switch S2 is open. The first DC voltage source V1 transmits a DC voltage to the output terminal of the switching sub-module 122 as a reference voltage signal. 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 identical to the reference voltage. Thus, 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-capacitance mode, the first switch S1 is open and the second switch S2 is closed. The first coding unit T1 transmits a self-capacitance coding signal to the output terminal of the switching sub-module 122 as a reference voltage signal. At this time, the reference voltage signal included in the input signal of the filter 131 is the self-capacitance coding signal, and the self-capacitance coding signal output by the first coding unit T1 is identical to the coding signal applied to the electrode 20. In order to remove the reference voltage signal included in the input signal, the filter 131 opens the third switch S3 and closes the fourth switch S4. The second coding unit T2 outputs a coding signal identical to the reference voltage signal. Thus, 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 one 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-capacitance coding signals with the same phase and amplitude as the coding signal applied to the electrode 20.

[0125] In the embodiments 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 fourth 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 open. The second DC voltage source V2 outputs a DC level identical to the reference voltage signal, enabling the filter 131 to remove the reference voltage signal introduced by the first DC voltage source V1. In the self-capacitance mode, the third switch S3 is open and the fourth switch S4 is closed. The second coding unit T2 outputs a self-capacitance coding signal identical to the reference voltage signal, enabling the filter 131 to remove the reference voltage signal introduced by the first coding unit T1. Thus, in both the mutual capacitance mode and the self-capacitance mode, the reference voltage signal included in the input signal of the filter 131 can be removed, thereby ensuring the accuracy of touch recognition in both the mutual capacitance mode and the self-capacitance mode.

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

[0127] Figure 9 The phase margin evaluation result of the touch detection circuit in this example is shown. As Figure 9 shown, when the loading of the touch screen or touch pad is less than or equal to 500 pF, by using capacitors with smaller capacitance values and resistors with smaller resistance values, while reducing the cost of the touch detection circuit, the phase margin can be above 45°. When the loading of the touch screen or touch pad is below 500 pF, the phase margin is still above 45°. Therefore, this touch detection circuit can work stably and normally. The 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. In the industry, it is required 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 cannot work properly.

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

[0129] Figure 11 The suppression effect of the touch detection circuit according to the embodiment of the present application on display interference is shown. As Figure 11As shown, when the test conditions are that the maximum cut-off frequency GBW of the first amplifier A1 is 10 MHz, the maximum slew rate SR is 20 V / μs, the open-loop gain is 120 dB, the main node is at 10 Hz, and the second pole is at 100 MHz, it shows that the display interference can be basically suppressed. Under the 1Vpp display interference input, the remaining display interference in the output signal of the amplification sub-module 111 is 4 mVpp, which basically does not occupy the dynamic range of the amplification sub-module 111. When the first capacitor C1 is 500 pF and the display interference input is 1Vpp, the remaining display interference in the output signal of the amplification sub-module 111 is 4 mVpp, and the suppression efficiency is approximately 0.4 / 1 / 20 = 99.8%.

[0130] Figure 10 and Figure 11 show the measured results of the simulation and prototype platforms. By suppressing the mutual capacitance coding base and display interference, that is, after obtaining the mean values of the coding base and display interference of each induction electrode channel, the corresponding subtraction is performed. Since the differences in the coding base and display interference between channels are relatively small, and the coding base and display interference of each channel are basically near the mean value, the remaining amounts of the coding base and display interference after subtraction are small, and the actual measurement can suppress it to within 1 mVpp.

[0131] Figure 12 and Figure 13 show the mutual capacitance touch change amount (touchdiff) effect of the touch detection circuit according to the embodiment of the present application. Among them, Figure 12 shows the mutual capacitance touch diff effect when one of the 5 channels is touched, Figure 13 shows the mutual capacitance touch diff effect when two of the 5 channels are touched. As Figure 12 shown, when a single channel is touched, the diff of this channel is 10 mVpp, and the diff of other channels is 2 mVpp. After compensating the mean base (error signal), the actual diff of this channel is 12 mVpp. As Figure 13 shown, when two channels are touched, the diff of these two channels is 8 mVpp, and the diff of other channels is 4 mVpp. After compensating the mean base, the actual diff of these two channels is 12 mVpp. From Figure 12 and Figure 13It can be seen that the touch detection circuit can normally amplify the signal during touch, and the mutual capacitance diff is approximately 12 mVpp. Since there is no loss in diff, after suppressing the coding base and display interference, the noise in the touch signal decreases, and the SNR can be significantly improved. Diff is obtained by compensating the mean channel according to the touched channel and the non-touched channel. For example, if channel 0 among 6 channels is touched, the diff of channel 0 is 10 mV, the output of the mean channel is 2 mV, and the diff of channel 0 after compensation is 12 mV, and the output of the mean channel is 12 mV / 6 = 2 mV.

[0132] Figure 14 and Figure 15 shows the self-capacitance touch change amount (touchdiff) effect of the touch detection circuit according to the embodiment of the present application. In Figure 14 , the ordinate V1 represents the input signal of the non-inverting input terminal of the first amplifier A1 in the amplification sub-module 111, and the ordinate represents the input signal of the inverting input terminal of the first amplifier A1 in the amplification sub-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 value amplification sub-module 123, V1 and V2 can also identify the output signal of the mean value amplification sub-module 123, that is, the mean value of the signals of each channel.

[0133] As Figure 14 shown, when there is no touch, the output of the amplification sub-module 111 of each of the 5 channels includes the output electrode (TX) base, as Figure 14 shown in TX = 2 Vpp. As Figure 15 shown, when 1 of the 5 channels is touched, the diff is approximately 1 mVpp. Among them, the first capacitor C1 = 300 pF, the self-capacitance change amount is 0.35 pF, the output electrode base is 2 Vpp, and the coding frequency is 100 KHz. From Figure 14 and Figure 15 it can be seen that the touch detection circuit can normally amplify the signal during touch, and the self-capacitance diff is approximately 1 mVpp. Figure 14 and Figure 15 are the measured results of the touch detection circuit provided by the embodiment of the present application. There is no loss in the self-capacitance diff. By suppressing the coding base and display interference, while increasing the amplification factor and reducing the display interference, the SNR is improved.

[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 foregoing embodiments is encapsulated in the chip. 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 embodiments of the present application is based on the same concept as the foregoing touch detection circuit embodiments. For the specific content and beneficial effects, reference can be made to the descriptions in the foregoing touch detection circuit embodiments, which will not be elaborated here.

[0137] Screen module

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

[0139] The electrode 20 can receive the touch drive signal output by the touch chip 161 to enable the screen module 160 to recognize a 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 embodiments of the present application is implemented based on the touch detection circuit 10 and the touch chip in the foregoing embodiments, and is a specific application of the touch detection circuit 10 and the touch chip in the foregoing embodiments. For the specific content and beneficial effects, reference can be made to the descriptions in the foregoing touch detection circuit embodiments, which will not be elaborated here.

[0141] It should be understood that each embodiment in this specification is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for the method embodiments, since they are basically similar to the methods described in the device and system embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of other embodiments.

[0142] It should be understood that the above describes specific embodiments of this specification. Other embodiments are within the scope of the claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require the specific order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0143] It should be understood that elements described herein in the singular or shown as only one in the drawings do not represent limiting the number of such elements to one. Additionally, modules or elements described or shown herein as separate may be combined into a single module or element, and modules or elements described or shown herein as a single one may be split into multiple modules or elements.

[0144] It should also be understood that the terms and expressions used herein are for descriptive purposes only, and one or more embodiments of this specification should not be limited to these terms and expressions. Using these terms and expressions does not mean excluding any equivalent features of the illustration and description (or parts thereof), and it should be recognized that various modifications that may exist should also be included within the scope of the claims. Other modifications, variations, and substitutions may also exist. Accordingly, the claims should be regarded as covering 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.

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