Self-capacitance correction method, touch control chip and touch control device

Abstract

The present application discloses a self-capacitance correction method, a touch chip and a touch device. The touch chip is connected to multiple signal channels of a touch screen. The touch chip includes a global capacitance unit and multiple local capacitance units. The global capacitance unit is connected to multiple signal channels, and each local capacitance unit is connected to one of the signal channels. The method includes: obtaining a first self-capacitance value of each signal channel; adjusting the global capacitance unit to a first capacitance value according to all first self-capacitance values; controlling the adjusted global capacitance unit to perform charge cancellation with each signal channel; obtaining a second self-capacitance value of each signal channel; adjusting the local capacitance unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value; controlling the adjusted local capacitance unit to perform charge superposition or cancellation with each signal channel, thereby correcting the self-capacitance value of the signal channel connected thereto to a target reference capacitance value. The present application can correct the self-capacitance value of the signal channel in real time.

Description

Technical Field

[0001] The present application relates to the field of touch control technology, and in particular to a self-capacitance correction method, a touch control chip and a touch control chip. Background Art

[0002] Currently, more and more electronic devices, such as foldable mobile phones and PADs, are using flexible screens. Flexible screens have advantages such as light weight, low power consumption, and the ability to be bent. However, the change in the display structure has brought great challenges to the self-capacitance detection of touch. Flexible screens are thinner than traditional LCD external screens, causing the touch sensing electrodes to be closer to the cathode of the OLED, so the self-capacitance of the sensing electrodes is also greater. For traditional external screens, the touch sensing electrodes are about tens of pF, while for flexible screens, this value rises to hundreds of pF.

[0003] Since the sensing electrode of the flexible screen has parasitic capacitance relative to the cathode layer, and this parasitic capacitance cannot be eliminated, the usual practice is to make a compensation circuit inside the touch chip to eliminate this capacitance, and use the subtraction base capacitance of this compensation circuit to eliminate the influence of this parasitic capacitance. A larger capacitance value of the sensing electrode requires a larger subtraction base capacitance.

[0004] The existing solution is to test a subtracted base capacitance value when testing the touch chip before it leaves the factory, and then write it into the memory for storage. This processing method is time-consuming and may cause failure when the environment changes during the use of the product. Summary of the invention

[0005] In view of this, the present application provides a self-capacitance correction method, a touch chip and a touch device, which can be used to correct the self-capacitance value of each signal channel in real time as needed, thereby ensuring the accuracy of touch operation recognition. The technical solution of the present application is as follows:

[0006] In a first aspect, the present application provides a self-capacitance correction method, which is applied to a touch chip, wherein the touch chip is connected to multiple signal channels of a touch screen, and the signal channels are used to transmit touch signals and complete touch detection. The touch chip also includes a global capacitor unit and multiple local capacitor units, wherein the global capacitor unit is connected to multiple signal channels, and each local capacitor unit is connected to one of the signal channels; the method includes: obtaining a first self-capacitance value of each signal channel; adjusting the global capacitor unit to a first capacitance value according to all the first self-capacitance values; controlling the adjusted global capacitor unit to perform charge cancellation with the self-capacitance of each signal channel; obtaining a second self-capacitance value of each signal channel after charge cancellation; adjusting the local capacitor unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value; controlling the adjusted local capacitor unit to perform charge superposition or cancellation with the self-capacitance of each signal channel, thereby correcting the self-capacitance value of the signal channel connected thereto to a target reference capacitance value.

[0007] In one embodiment of the present application, obtaining the first self-capacitance value of each of the signal channels includes: adjusting the global capacitance unit to a preset capacitance value; controlling the adjusted global capacitance unit and the self-capacitance of the signal channel to cancel out charges; detecting the voltage value of each of the signal channels after charge cancellation; and using the capacitance value corresponding to the voltage value as the first self-capacitance value of each of the signal channels.

[0008] In one embodiment of the present application, the global capacitor unit includes M global capacitors connected in parallel and M switches arranged on the parallel circuit of the global capacitors; the global capacitor unit is adjusted to the first capacitance value according to all the first self-capacitance values, including: (a) controlling one of the M switches to be turned on and the remaining switches of the M switches to be turned off; (b) obtaining the voltage value of each of the signal channels; (c) when it is determined that the voltage value of each of the signal channels is greater than or equal to a preset voltage value, determining that the current switch remains turned on; (d) when it is determined that the voltage value of each of the signal channels is less than the preset voltage value, controlling the current switch to be turned off; (e) controlling the next switch of the M switches to be turned on, and executing step (b) until all the on and off states of the M switches are determined, and the capacitance of the turned-on global capacitor is obtained as the first capacitance value of the global capacitor unit.

[0009] In one embodiment of the present application, the global capacitor unit includes M global capacitors connected in parallel and M switches arranged on the parallel circuit of the global capacitors; the adjusting the global capacitor unit to the first capacitance value according to all the first self-capacitance values ​​includes: (a) controlling one of the M switches to be turned on and the remaining switches of the M switches to be turned off; (b) obtaining the voltage value of each of the signal channels; (c) screening out the target voltage value that deviates the most from the preset voltage value from all the voltage values; (d) determining that the current switch remains turned on when it is determined that the target voltage value is greater than the preset voltage value; (e) controlling the current switch to be turned off when it is determined that the target voltage value is less than the preset voltage value; (f) controlling the next switch of the M switches to be turned on, and executing step (b) until all the on-off states of the M switches are determined, and the capacitance of the turned-on global capacitor is obtained as the first capacitance value of the global capacitor unit.

[0010] In one embodiment of the present application, obtaining the second self-capacitance value of each of the signal channels after charge cancellation includes: obtaining the voltage value of the signal channel after charge cancellation; and using the capacitance value corresponding to the voltage value as the second self-capacitance value.

[0011] In one embodiment of the present application, adjusting the local capacitance unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value includes: comparing the voltage value with a preset voltage value; when the voltage value is less than the preset voltage value, determining that the local capacitance unit is used for charge superposition, and adjusting the local capacitance unit to the second capacitance value based on the difference between the preset voltage value and the voltage value; when the voltage value is greater than the preset voltage value, determining that the local capacitance unit is used for charge cancellation, and adjusting the local capacitance unit to the second capacitance value based on the difference between the voltage value and the preset voltage value; when the voltage value is equal to the preset voltage value, not adjusting the local capacitance unit.

[0012] In a second aspect, the present application provides a touch chip connected to multiple signal channels in a touch screen, wherein the signal channels are used to transmit touch signals and complete touch detection, and the touch chip also includes: a global capacitor unit, wherein the global capacitor unit is used to connect to multiple signal channels; multiple local capacitor units, wherein each local capacitor unit is used to connect to one of the signal channels; a control unit, wherein the control unit is used to connect to each signal channel, the global capacitor unit, and each local capacitor unit; the control unit is used to obtain a first self-capacitance value of each signal channel; and adjust the global capacitor unit to a first capacitance value according to all the first self-capacitance values; and control the adjusted global capacitor unit to cancel the self-capacitance of each signal channel for charge; and obtain a second self-capacitance value of each signal channel after charge cancellation; and adjust the local capacitor unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value; and control the adjusted local capacitor unit to superimpose or cancel the self-capacitance of each signal channel for charge, thereby correcting the self-capacitance value of the signal channel connected thereto to a target reference capacitance value.

[0013] In one embodiment of the present application, it also includes: a plurality of self-capacitance detection units, each of which is used to connect to one of the signal channels, or each of which is used to connect to one of the signal channels in time-sharing manner, and each of which is connected to the control unit; the self-capacitance detection unit is used to detect the self-capacitance value of the signal channel connected thereto, convert the self-capacitance value into a voltage value, and transmit the voltage value to the control unit; the self-capacitance detection unit includes a voltage comparator, a feedback capacitor and a reset switch, wherein the negative input terminal of the voltage comparator is connected to the signal channel, one end of the feedback capacitor is connected to the negative input terminal of the voltage comparator, and the other end is connected to the output terminal of the voltage comparator, one end of the reset switch is connected to the negative input terminal of the voltage comparator, and the other end is connected to the output terminal of the voltage comparator, and the positive input terminal of the voltage comparator is connected to a reference voltage.

[0014] In one embodiment of the present application, the local capacitor unit includes a local capacitor with adjustable capacitance, a first switch group and a second switch group, wherein the first switch group and the second switch group are arranged on a circuit where the local capacitor is connected to one of the signal channels; the first switch group includes three first switches, and the second switch group includes three second switches, wherein one end of one of the second switches is connected to the signal channel and the other end is grounded; the first end of the local capacitor is connected to the negative input terminal of the voltage comparator through two first switches, and receives the capacitor voltage through a second switch, the two first switches are both connected to the signal channel, the second end of the local capacitor is grounded through one of the second switches, and receives the capacitor voltage through one of the first switches.

[0015] In one embodiment of the present application, it further includes: a current mirror unit, the global capacitor unit is connected to each of the signal channels through the current mirror unit, and the current mirror unit is used to copy the charge of the global capacitor unit to each of the signal channels.

[0016] In an embodiment of the present application, the global capacitor unit includes M global capacitors connected in parallel and M global capacitor switches arranged on the parallel circuit of the global capacitors.

[0017] In a third aspect, the present application provides a touch device, wherein the touch device is provided with a plurality of signal channels, wherein the signal channels are used to transmit touch signals and complete touch detection, and further comprises a touch chip, wherein the touch chip is connected to the plurality of signal channels in the touch device, and the touch chip further comprises: a global capacitor unit, wherein the global capacitor unit is used to be connected to the plurality of signal channels; a plurality of local capacitor units, wherein each local capacitor unit is used to be connected to one of the signal channels; a control unit, wherein the control unit is used to be connected to each of the signal channels, the global capacitor unit, and each local capacitor unit; the control unit is used to obtain a first self-capacitance value of each of the signal channels; and adjust the global capacitor unit to a first capacitance value according to all the first self-capacitance values; and control the adjusted global capacitor unit to cancel the self-capacitance of each of the signal channels for charge; and obtain a second self-capacitance value of each of the signal channels after charge cancellation; and adjust the local capacitor unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value; and control the adjusted local capacitor unit to perform charge superposition or cancellation with the self-capacitance of each of the signal channels, thereby correcting the self-capacitance value of the signal channel connected thereto to a target reference capacitance value.

[0018] The beneficial effects brought about by the technical solution provided by the present application include at least: by setting a global capacitance unit connected to each signal channel of the touch screen, and setting a local capacitance unit for each signal channel, when it is necessary to perform self-capacitance correction on the signal channel, first adjust the global capacitance unit so that the self-capacitance values ​​of all signal channels are close to the target reference capacitance value, and then adjust the local capacitance unit of each signal channel, and finally, after the global capacitance unit and the local capacitance unit are superimposed or offset by the charge, correct the self-capacitance value of the signal channel connected to it to the target reference capacitance value, thereby realizing the real-time correction function of the self-capacitance value of the signal channel. Even if the long-term use of the touch screen causes the self-capacitance value of the signal channel to change, it can be corrected in time, thereby ensuring the accuracy of touch operation recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of a touch screen provided in an embodiment of the present application.

[0020] Figure 2 It is a flow chart of a self-capacitance correction method provided in an embodiment of the present application.

[0021] Figure 3 It is a flowchart of a first self-capacitance value acquisition method provided in an embodiment of the present application.

[0022] Figure 4 It is a flow chart of a global capacitor unit adjustment method provided in an embodiment of the present application.

[0023] Figure 5 It is a flow chart of a global capacitor unit adjustment method provided in an embodiment of the present application.

[0024] Figure 6 It is a flow chart of a local capacitor unit adjustment method provided in an embodiment of the present application.

[0025] Figure 7 It is a schematic diagram of the structure of a touch chip connected to a signal channel provided in an embodiment of the present application.

[0026] Figure 8 It is a structural schematic diagram of a global capacitor unit provided in an embodiment of the present application.

[0027] Fig. 9 It is a schematic diagram of the structure of another touch chip connected to a signal channel provided in an embodiment of the present application.

[0028] Fig.10 It is a circuit diagram of a CA self-capacitance detection circuit provided in an embodiment of the present application.

[0029] Fig.11This is a circuit diagram of a local capacitor unit provided in an embodiment of the present application.

[0030] Fig.12 This is a control timing diagram of a first switch group, a second switch group and a reset switch provided in an embodiment of the present application.

[0031] Fig.13 4 is a schematic diagram of the structure of a touch chip connected to a signal channel provided in an embodiment of the present application.

[0032] Fig.14 This is a circuit diagram of a global capacitance unit connected to a self-capacitance detection unit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] It should be noted that in the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0034] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchangeable with each other, and some of the steps can also be deleted.

[0035] At present, with the continuous advancement of touch screen technology, the human-computer interaction functions of most electronic products on the market are realized by touch screens, especially various electronic terminal products, such as mobile phones, tablet computers, notebooks, e-books and other electronic terminals, most of which use capacitive touch screens for human-computer interaction.

[0036] Moreover, the flexible touch screen has obvious advantages such as thin volume, low power consumption and bendability, so more and more manufacturers have adopted flexible touch screens in order to provide users with better product experience. The encapsulation layer between the touch electrode layer of the flexible touch screen and the cathode layer of the light-emitting diode is generally a thin film flexible structure, so the distance between the touch electrode layer and the cathode layer of the flexible touch screen is relatively close compared to the traditional external touch screen, which leads to a relatively large self-capacitance value of the signal channel formed by the touch electrode in the touch electrode layer. In the process of the flexible touch screen detecting the change of the self-capacitance value of the signal channel and then detecting the touch operation, a relatively large correction capacitor (corresponding to the subtraction base capacitor in the background technology) is required to compensate for the self-capacitance value of the signal channel, so that the self-capacitance value of the signal channel of the flexible touch screen reaches the reference capacitance value.

[0037] In the existing related art, in order to make the self-capacitance value of each signal channel of the touch screen approach the reference capacitance value, a correction capacitor with a larger capacitance value is connected to each signal channel of the touch screen. In addition, since the self-capacitance value of each signal channel will be different, the touch screen manufacturer will find a correction capacitance value through testing before the touch screen leaves the factory, and then store it in the chip of the touch screen. When the correction capacitor of the correction capacitance value is used to offset the self-capacitance value of each signal channel, the self-capacitance value of each signal channel can only be made close to the reference capacitance value. Since the correction capacitor cannot be adjusted later, when the self-capacitance value of the signal channel changes due to the change in the use environment of the touch screen, its corrected self-capacitance value will deviate more and more from the reference capacitance value, thereby affecting the accuracy of the touch screen in detecting touch operations.

[0038] The embodiment of the present application provides a self-capacitance correction method, which is applied to a touch chip, so that the touch chip can correct the subtracted base capacitance value of each signal channel of the touch screen in real time as needed. When the self-capacitance value of the signal channel changes due to the change in the use environment of the touch screen, the accurately corrected self-capacitance value can still be obtained, and the corrected self-capacitance value is equal to or close to the reference capacitance value, thereby ensuring the accuracy of touch operation recognition.

[0039] Please refer to Figure 1 , is a schematic diagram of the structure of a touch screen provided in an embodiment of the present application. The touch screen 100 includes a plurality of signal channels 110, a global capacitor unit 120, and a plurality of local capacitor units 130, wherein the global capacitor unit 120 is connected to each signal channel 110, and each local capacitor unit 130 is connected to one of the signal channels 110.

[0040] The signal channel 110 may be a single touch electrode, or may be formed by connecting a plurality of touch electrodes. The signal channel 110 is first used to transmit a touch signal, and then sense the touch signal. The touch point of the conductor on the touch screen 100 will change the self-capacitance value of the coupling node. The touch screen 100 obtains the charge information generated by the change of the self-capacitance value through an analog circuit, converts it into a digital signal and transmits it to a microprocessor to detect the self-capacitance value of the touch point, thereby calculating the coordinates of the touch point on the touch screen 100. The touch signal includes a carrier signal with a preset frequency.

[0041] In the embodiment of the present application, both the global capacitor unit 120 and the local capacitor unit 130 have adjustable capacitance values, and the capacitance value of the global capacitor unit 120 can be much greater than the capacitance value of the local capacitor unit 130 .

[0042] Please refer to Figure 2 , is a flow chart of a self-capacitance correction method provided in an embodiment of the present application. The self-capacitance correction method is applied to the above Figure 1 The touch screen shown. The self-capacitance correction method comprises the following steps:

[0043] Step S21: Obtain a first self-capacitance value of each signal channel.

[0044] In the embodiment of the present application, when the touch screen needs to calibrate the self-capacitance value of each signal channel, it can first obtain the first self-capacitance value of each signal channel by detection. Among them, since each signal channel is connected to the global capacitance unit, and each signal channel is connected to one of the local capacitance units, the touch screen can first control the disconnection of the global capacitance unit and the signal channel, and disconnect the local capacitance unit and the signal channel, and then obtain the first self-capacitance value to ensure the accuracy of the first self-capacitance value.

[0045] Among them, the global capacitor unit can be connected to the signal channel through the first switch unit, and the local capacitor unit can also be connected to the signal channel through the second switch unit. The touch screen also includes a control unit, which controls the disconnection of the first switch unit or the second switch unit by sending control instructions to the first switch unit and the second switch unit.

[0046] Alternatively, since the global capacitor unit and the local capacitor unit are adjustable in capacitance value, the control unit is directly connected to the global capacitor unit and the local capacitor unit. Before obtaining the first self-capacitance value of the signal channel, a control instruction is sent to the global capacitor unit and the local capacitor unit to initialize the global capacitor unit and the local capacitor unit to the initialization value, and then the current self-capacitance value of each signal channel is obtained, and finally the first self-capacitance value is obtained according to the current self-capacitance value and the initialization value.

[0047] Step S22: adjusting the global capacitance unit to a first capacitance value according to all first self-capacitance values.

[0048] In the embodiment of the present application, after obtaining the first self-capacitance value of each signal channel of the touch screen, the control unit of the touch screen will first adjust the global capacitance unit according to the first self-capacitance value, so that the global capacitance unit reaches the first capacitance value. The function of the global capacitance unit is mainly to make the self-capacitance value of the signal channel approach the reference capacitance value through charge cancellation. Therefore, in addition to considering the first self-capacitance value, the reference capacitance value can also be considered when adjusting the global capacitance unit.

[0049] For example, when the reference capacitance value is 0, the control unit of the touch screen can calculate the average value based on all the first self-capacitance values, which is the average self-capacitance value, and adjust the first capacitance value of the global capacitance unit to the average capacitance value. Alternatively, from all the first self-capacitance values, the middle value of the first self-capacitance value is screened out, and the first capacitance value of the global capacitance unit is adjusted to the middle value. Alternatively, from all the first self-capacitance values, the minimum value of the first self-capacitance value is screened out, and the first self-capacitance value of the global capacitance unit is adjusted to the minimum value. Alternatively, from all the first self-capacitance values, the maximum value of the first self-capacitance value is screened out, and the first self-capacitance value of the global capacitance unit is adjusted to the maximum value.

[0050] Similarly, when the reference capacitance value is not 0, the reference capacitance value is first subtracted from each first self-capacitance value to obtain multiple capacitance differences, and then the above-mentioned average value calculation, intermediate value, minimum value and maximum value screening are performed from the multiple capacitance differences, and finally the first capacitance value of the global capacitance unit is obtained.

[0051] Step S23: controlling the adjusted global capacitance unit and the self-capacitance of each signal channel to cancel out charges.

[0052] In the embodiment of the present application, the adjusted global capacitance unit can be used to make the self-capacitance value of the signal channel approach the reference capacitance value through charge cancellation. From the above, it can be seen that when the touch screen is performing touch detection, a carrier signal will be sent in the signal channel. When the carrier signal is transmitted in the signal channel, the self-capacitance of the signal channel will generate charge. While the signal channel transmits the carrier signal, an inverted signal is transmitted to the global capacitance unit, which can cause the global capacitance unit to generate an inverted charge. According to the law of charge conservation, the inverted charge can cancel the charge of the signal channel, thereby making the self-capacitance value of the signal channel approach the reference capacitance value.

[0053] The phase of the anti-phase signal is opposite to that of the carrier signal, and the amplitude of the anti-phase signal can be equal to the carrier signal. The amount of anti-phase charge generated by the global capacitor unit is related to its first capacitance value. One end of the global capacitor unit is connected to the signal channel, and the other end is used to input the anti-phase signal when the charge is offset.

[0054] Step S24: obtaining a second self-capacitance value of each signal channel after charge cancellation.

[0055] In the embodiment of the present application, after the adjusted global capacitance unit is used to cancel the charge with each signal channel, the second self-capacitance value of each signal channel is detected again. The second self-capacitance value of each signal channel may be equal to the reference capacitance value, or less than the reference capacitance value, or greater than the reference capacitance value.

[0056] In the example of step S22, when the required reference capacitance value is not 0, if the first capacitance value is an average value or a middle value of a plurality of capacitance differences (the capacitance difference is each first self-capacitance value minus the reference capacitance value), the plurality of second self-capacitance values ​​include being equal to the reference capacitance value, or being less than the reference capacitance value, or being greater than the reference capacitance value.

[0057] If the first capacitance value is the minimum value of a plurality of capacitance differences, the plurality of second self-capacitance values ​​include being equal to a reference capacitance value, or being greater than the reference capacitance value.

[0058] If the first capacitance value is the maximum value of a plurality of capacitance differences, the plurality of second self-capacitance values ​​include being equal to a reference capacitance value, or being smaller than the reference capacitance value.

[0059] Step S25: adjusting the local capacitance unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value.

[0060] In the embodiment of the present application, the main function of the local capacitance unit is to further adjust the self-capacitance value of the corresponding channel, so that the self-capacitance value of the signal channel is equal to the target reference capacitance value, or further make the signal channel approach the reference capacitance value.

[0061] Step S26: controlling the adjusted local capacitance unit to perform charge superposition or charge cancellation with the self-capacitance of each signal channel, thereby correcting the self-capacitance value of the signal channel connected thereto to the target reference capacitance value.

[0062] In the embodiment of the present application, the above-mentioned second self-capacitance value can be used to determine whether the self-capacitance value of the current signal channel is equal to the target reference capacitance value, or is less than the target reference capacitance value, or is greater than the target reference capacitance value. When the second self-capacitance value of the current signal channel is equal to the target reference capacitance value, that is, there is no need to correct the self-capacitance value of the current signal channel, the corresponding local capacitance unit can be controlled to be disconnected, or controlled to fail, or its capacitance value can be controlled to be 0.

[0063] When the second self-capacitance value of the current signal channel is less than the target reference capacitance value, the self-capacitance value of the current signal channel needs to be corrected to increase it to the target reference capacitance value. At this time, the difference between the second capacitance value and the target reference capacitance value is calculated, and the corresponding local capacitance unit is adjusted with the difference. During correction, a positive phase signal with the same phase as the carrier signal is transmitted to the local capacitance unit.

[0064] When the second self-capacitance value of the current signal channel is greater than the target reference capacitance value, the self-capacitance value of the current signal channel needs to be corrected to reduce it to the target reference capacitance value. At this time, the difference between the target reference capacitance value and the second capacitance value is calculated, and the corresponding local capacitance unit is adjusted with the difference. During correction, an inverted signal with an opposite phase to the carrier signal is transmitted to the local capacitance unit.

[0065] In an embodiment of the present application, a global capacitance unit is set to be connected to each signal channel of the touch screen, and a local capacitance unit is set for each signal channel. When it is necessary to perform self-capacitance correction on the signal channel, the global capacitance unit is first adjusted to make the self-capacitance values ​​of all signal channels approach the target reference capacitance value, and then the local capacitance unit of each signal channel is adjusted. Finally, after the charges of the global capacitance unit and the local capacitance unit are superimposed or offset, the self-capacitance value of the signal channel connected thereto is corrected to the target reference capacitance value, thereby realizing the real-time correction function of the self-capacitance value of the signal channel. Even if the use environment of the touch screen changes and causes the self-capacitance value of the signal channel to change, real-time correction can be performed, thereby ensuring the accuracy of touch operation recognition.

[0066] Please refer to Figure 3 , is a flow chart of a method for obtaining a first self-capacitance value provided in an embodiment of the present application. The method is one implementation of the above step S21, and specifically includes the following steps:

[0067] Step S31: adjusting the global capacitance unit to a preset capacitance value.

[0068] In an embodiment of the present application, when a touch signal is transmitted through a signal channel, the voltage value of the signal channel can be detected, and the voltage value can be converted into a first self-capacitance value, or the voltage value can be directly used as the first self-capacitance value. In order to adjust the signal channel to the target reference capacitance value more quickly, the global capacitance unit can be adjusted to a preset capacitance value to offset the charge with the signal channel. The preset capacitance value can be, for example, half of the capacitance value within the adjustable range of the global capacitance unit, or when the global capacitance unit is a multi-digit switch capacitor, the switch of the highest digit can be controlled to close, so that the switch capacitance corresponding to the highest digit is used as the preset capacitance value.

[0069] Step S32: controlling the adjusted global capacitance unit and the self-capacitance of the signal channel to cancel out charges.

[0070] In the embodiment of the present application, by transmitting a positive phase signal to the signal channel and transmitting a negative phase signal to the global capacitor unit, the charge of the global capacitor unit and the self-capacitance of the signal channel are offset. The positive phase signal and the negative phase signal have opposite phases, and the positive phase signal can be a touch signal of the touch screen, or a carrier signal generated by the touch screen control unit for detecting the self-capacitance of the signal channel.

[0071] Step S33: detecting the voltage value of each signal channel after the charge is offset.

[0072] Step S34: using the capacitance value corresponding to the voltage value as the first self-capacitance value of each signal channel.

[0073] In an embodiment of the present application, by pre-adjusting the global capacitor to a preset capacitance value, obtaining the voltage value of each signal channel, and converting the corresponding capacitance value based on the voltage value as the first self-capacitance value of the signal channel, the number of subsequent adjustments to the global capacitor can be reduced, thereby further improving the speed of adjusting the self-capacitance value of the signal channel to the target reference capacitance value.

[0074] Please refer to Figure 4 , is a flow chart of a global capacitor unit adjustment method provided in an embodiment of the present application, wherein the method is one of the implementations of the above step S22, and the global capacitor unit in the method includes M global capacitors connected in parallel, and M switches arranged on the parallel circuit of the global capacitors. Specifically, the following steps are included:

[0075] Step S41: controlling one of the M switches to be turned on, and the remaining switches of the M switches to be turned off.

[0076] In an embodiment of the present application, the above-mentioned M global capacitors may include global capacitors with the same capacitance value and global capacitors with different capacitance values. By controlling the conduction or disconnection of any switch among the M switches, any global capacitor can be controlled to be connected in parallel, and the global capacitor unit can be adjusted to the corresponding capacitance value.

[0077] Among them, before obtaining the voltage value of the signal channel and adjusting the switch control of the global capacitor according to the voltage value, one of the switches can be controlled to be turned on to adjust the global capacitor unit to an initial capacitance value. For example, the switch related to the global capacitor with the largest capacitance value in the global capacitor can be controlled to be turned on, so as to adjust the global capacitor unit to the corresponding capacitance value.

[0078] Step S42: Obtain the voltage value of each signal channel.

[0079] Step S43: when it is determined that the voltage value of each signal channel is greater than or equal to the preset voltage value, determining that the current switch remains turned on.

[0080] In the embodiment of the present application, the above-mentioned preset voltage value is the voltage value corresponding to the signal channel after adjusting to the target reference capacitance value. Therefore, when it is determined that the voltage value of each signal channel is greater than the preset voltage value, it means that the capacitance value of the current global capacitance unit is relatively small and its capacitance value needs to be further increased, that is, it is necessary to determine that the current switch remains turned on, and then turn on other switches to increase the capacitance value.

[0081] Step S44: when it is determined that the voltage value of each signal channel is less than the preset voltage value, the current switch is controlled to be disconnected.

[0082] In an embodiment of the present application, when it is determined that the voltage value of each signal channel is less than the preset voltage value, it means that the capacitance value of the global capacitor unit that turns on the current switch is relatively large, and other global capacitors need to be selected in parallel for comparison, that is, the current switch needs to be disconnected and then other switches need to be turned on to adjust the capacitance value.

[0083] Step S45: control the next switch of the M switches to be turned on, and execute step S42 until all the on and off states of the M switches are determined, and the capacitance of the turned-on global capacitor is obtained as the first capacitance value of the global capacitor unit.

[0084] In the embodiment of the present invention, by controlling the next switch to turn on and then returning to execute step S42, it is possible to determine whether the working state of the M switches is on or off, thereby determining the first capacitance value of the global capacitance unit, and ultimately making the self-capacitance values ​​of most signal channels approach the target reference capacitance value when the global capacitance unit with the first capacitance value performs charge offset on all signal channels.

[0085] Please refer to Figure 5, is a flow chart of a global capacitor unit adjustment method provided in an embodiment of the present application, wherein the method is another implementation of the above step S22, and the global capacitor unit in the method includes M global capacitors connected in parallel, and M switches arranged on the parallel circuit of the global capacitors. Specifically, the following steps are included:

[0086] Step S51: controlling one of the M switches to be turned on, and the remaining switches of the M switches to be turned off.

[0087] Step S52: Obtain the voltage value of each signal channel.

[0088] Step S53: Filter out the target voltage value that deviates the most from the preset voltage value from all the voltage values.

[0089] In the embodiment of the present application, after controlling the current switch to be turned on, after using the global capacitance unit of the current corresponding capacitance value to offset the charge of each signal channel, the voltage value of each signal channel obtained will also include the situation that it is greater than the preset voltage value, equal to the preset voltage value, and less than the preset voltage value. When all three situations are included, it is necessary to obtain the target voltage value that deviates the most from the preset voltage value to determine the on-off state of the current switch. Among them, the deviation is the difference between the voltage value and the preset voltage value.

[0090] Step S54: when it is determined that the target voltage value is greater than the preset voltage value, determining that the current switch remains turned on.

[0091] In an embodiment of the present application, when it is determined that the target voltage value is greater than the preset voltage value, that is, there is a signal channel with a relatively large self-capacitance value, and the capacitance value of the current global capacitance unit is relatively small, after charge compensation, the self-capacitance value of the signal unit is still far from the target reference capacitance value. Therefore, it is necessary to determine that the current switch remains turned on, and then further turn on other switches to increase the capacitance value.

[0092] Step S55: When it is determined that the target voltage value is less than the preset voltage value, the current switch is controlled to be disconnected.

[0093] In the embodiment of the present application, when it is determined that the target voltage value is less than the preset voltage value, that is, the self-capacitance value of the signal channel is relatively small, and the capacitance value of the current global capacitance unit is relatively large, resulting in the self-capacitance value of the signal unit being far different from the target reference capacitance value after charge cancellation. Therefore, the current switch is disconnected and the switch corresponding to the global capacitor with a smaller capacitance value is selected to control the closure.

[0094] Step S56: control the next switch of the M switches to be turned on, and execute step S52 until all the on and off states of the M switches are determined, and the capacitance of the turned-on global capacitor is obtained as the first capacitance value of the global capacitor unit.

[0095] In the embodiment of the present invention, by controlling the next switch to turn on and then returning to execute step S52, it is possible to determine whether the working state of the M switches is on or off, thereby determining the first capacitance value of the global capacitance unit, and ultimately making the self-capacitance values ​​of most signal channels approach the target reference capacitance value when the global capacitance unit with the first capacitance value performs charge offset on all signal channels.

[0096] Please refer to Figure 6 , is a flow chart of a local capacitor unit adjustment method provided in an embodiment of the present application, wherein the method is one of the implementations of the above-mentioned step S24 and step S25, and specifically includes the following steps:

[0097] Step S61: obtaining the voltage value of the signal channel after charge cancellation.

[0098] Step S62: taking the capacitance value corresponding to the voltage value as the second self-capacitance value.

[0099] Step S63: comparing the voltage value with a preset voltage value.

[0100] Step S64: when the voltage value is less than the preset voltage value, determine that the local capacitor unit is used for charge superposition, and adjust the local capacitor unit to a second capacitance value according to the difference between the preset voltage value and the voltage value.

[0101] In the embodiment of the present application, after determining the first capacitance value of the global capacitance unit, the second capacitance value of the local capacitance unit corresponding to each signal channel is adjusted. Since the global capacitance unit is reused for multiple signal channels, after the global capacitance unit with the adjusted first capacitance value and each signal channel perform charge cancellation, the second self-capacitance value of each signal channel will be different, and there may be a situation where it is greater than the target reference capacitance value, less than the target reference capacitance value, or equal to the target reference capacitance value.

[0102] Among them, for a signal channel that is less than the target reference capacitance value, that is, when the voltage value of the signal channel is less than the preset voltage value, it is determined that the second self-capacitance value of the signal channel is still less than the target reference capacitance value, it is necessary to increase the self-capacitance value of the current signal channel by charge superposition through the corresponding local capacitance unit. Among them, the above-mentioned second capacitance value is the difference between the target reference capacitance value and the second self-capacitance value. The second capacitance value can be obtained by the above-mentioned difference conversion, or the local capacitance unit can be controlled to change its capacitance value from small to large, and finally adjusted to the second capacitance value.

[0103] Since the local capacitance unit is used for charge superposition to increase the self-capacitance value of the current signal channel, the signal input during correction is a signal with the same phase as the positive phase signal of the signal channel.

[0104] Step S65: when the voltage value is greater than the preset voltage value, determine that the local capacitor unit is used for charge compensation, and adjust the local capacitor unit to a second capacitance value according to the difference between the voltage value and the preset voltage value.

[0105] In an embodiment of the present application, for a signal channel greater than the target reference capacitance value, that is, when the voltage value of the signal channel is greater than the preset voltage, it is determined that the second self-capacitance value of the signal channel is also greater than the target reference voltage value, and it is necessary to use the corresponding local capacitor to perform charge offset to reduce the self-capacitance value of the current signal channel. Among them, the above-mentioned second capacitance value is the difference between the second self-capacitance value and the target reference voltage value. The second capacitance value can be obtained by the above-mentioned difference conversion, or the local capacitance unit can be controlled to change its capacitance value from small to large, and finally adjusted to the second capacitance value.

[0106] Since the local capacitance unit is used for charge cancellation to reduce the self-capacitance value of the current signal channel, the signal input during calibration is an anti-phase signal having a phase opposite to that of the positive-phase signal of the signal channel.

[0107] Step S66: when the voltage value is equal to the preset voltage value, the local capacitor unit is not adjusted.

[0108] In an embodiment of the present application, if the voltage value of the current signal channel is equal to the preset voltage value, it means that after the charge offset of the above-mentioned global capacitor unit, the self-capacitance value of the signal channel is equal to the target reference capacitance value, so there is no need to adjust the local capacitor unit connected to it.

[0109] Please refer to Figure 7 , is a schematic diagram of the structure of a touch chip connected to a signal channel provided in an embodiment of the present application.

[0110] The touch chip is connected to a plurality of signal channels 710 in the touch screen. The signal channels 710 are used to transmit touch signals and complete touch detection. The touch chip also includes:

[0111] The global capacitor unit 720 is connected to the plurality of signal channels 710 .

[0112] A plurality of local capacitor units 730 are provided, and each local capacitor unit 730 is connected to one of the signal channels 710 .

[0113] The control unit 740 is connected to each signal channel 710 , the global capacitor, and each local capacitor.

[0114] The control unit 740 is used to obtain the first self-capacitance value of each signal channel 710; and adjust the global capacitance unit 720 to the first capacitance value according to all the first self-capacitance values; and control the adjusted global capacitance unit 720 to cancel the charge with the self-capacitance of each signal channel 710; and obtain the second self-capacitance value of each signal channel 710 after the charge cancellation; and adjust the local capacitance unit 730 connected to the corresponding signal channel 710 to the second capacitance value according to the second self-capacitance value; and control the adjusted local capacitance unit 730 to superimpose or cancel the charge with the self-capacitance of each signal channel 710, thereby correcting the self-capacitance value of the signal channel 710 connected thereto to the target reference capacitance value.

[0115] like Figure 8 As shown, the global capacitor unit 720 includes M global capacitors 721 connected in parallel, and M global capacitor switches 722 arranged in the parallel circuit of the global capacitors. The control and adjustment process of each global capacitor 721 and the global capacitor switch 722 in the global capacitor unit 720 can refer to the aforementioned Figure 4 , Figure 5 and a description of the relevant content.

[0116] Please refer to Fig. 9 , is a schematic diagram of the structure of another touch chip connected to a signal channel provided in an embodiment of the present application.

[0117] Among them, Figure 7 Compared with the touch chip in Fig. 9 The difference of the touch chip is that it also includes:

[0118] A plurality of self-capacitance detection units 750 , each of which is connected to one of the signal channels 710 , or each of which is used to be connected to a signal channel in a time-sharing manner and each of which is connected to the control unit 740 .

[0119] The self-capacitance detection unit 750 is used to detect the self-capacitance value of the signal channel 710 connected thereto, convert the self-capacitance value into a preset type electrical parameter, and transmit the preset type electrical parameter to the control unit 740 .

[0120] In the embodiment of the present application, when the signal channel 710 is used to transmit a touch signal, the self-capacitance detection unit 750 can detect the corresponding self-capacitance value and output the corresponding preset type point parameter. In addition, when the signal channel 710 is connected to the global capacitance unit 720 and the local capacitance unit 730 to calibrate the self-capacitance value, the self-capacitance detection unit 750 can also detect the calibrated self-capacitance value and output the corresponding preset type point parameter.

[0121] The self-capacitance detection unit 750 includes a CA self-capacitance detection circuit, and the preset type electrical parameter output by the CA self-capacitance detection circuit is a voltage value. Fig.10 , which is a circuit diagram of a CA self-capacitance detection circuit provided in an embodiment of the present application.

[0122] The CA self-capacitance detection circuit includes: a voltage comparator 751, a feedback capacitor cf and a reset switch rst. The negative input terminal of the voltage comparator 751 is connected to the signal channel 710. One end of the feedback capacitor cf is connected to the negative input terminal of the voltage comparator 751, and the other end is connected to the output terminal of the voltage comparator 751. One end of the reset switch rst is connected to the negative input terminal of the voltage comparator 751, and the other end is connected to the output terminal of the voltage comparator 751. The positive input terminal of the voltage comparator 751 is connected to the reference voltage VREF.

[0123] The on-off control of the switch rst corresponds to the touch signal transmitted on the signal channel. For example, when the touch signal transmitted on the signal channel is a square wave, the switch rst is turned on at a high level and is turned off at a low level. After the self-capacitance calibration process of all signal channels 710 is completed, the CA self-capacitance detection circuit will also be used to detect the touch operation, that is, when detecting the touch operation, the voltage value signal is obtained through the CA self-capacitance detection circuit and transmitted to the calculation unit (not shown in the figure) for calculating the touch coordinates in the touch chip, so as to calculate the corresponding touch coordinates according to the voltage value signal.

[0124] Please refer to Fig.11 , is a circuit diagram of a local capacitor unit provided in an embodiment of the present application. The local capacitor unit 730 includes a local capacitor Cb with adjustable capacitance, a first switch group and a second switch group, wherein the first switch group and the second switch group are arranged on a circuit connecting the local capacitor and one of the signal channels.

[0125] like Fig.11 As shown in , the first switch group includes three first switches Φ1, and the second switch group includes three second switches Φ2. One end of one of the second switches Φ2 is connected to the signal channel 710, and the other end is grounded. The first end of the local capacitor Cb is connected to the negative input end of the voltage comparator 751 through two first switches Φ1, and receives the capacitor voltage VDD through a second switch Φ2, and the two first switches Φ1 are connected to the signal channel 710. The second end of the local capacitor Cb is grounded through one of the second switches Φ2, and receives the capacitor voltage VDD through one of the first switches Φ1.

[0126] Please refer to Fig.12, is a control timing diagram of a first switch group, a second switch group and a reset switch provided in an embodiment of the present application. The control timing diagram includes a level control signal transmitted to the reset switch rst, a level control signal transmitted to a plurality of first switches Φ1, a level control signal transmitted to a plurality of second switches Φ2, and a voltage signal CA_out at the output end of the voltage comparator 751. The high level segment of the level control signal controls the switch to be closed, and the low level end of the level control signal controls the switch to be closed.

[0127] The reset switch rst, the plurality of first switches Φ1 and the plurality of second switches Φ2 are controlled by the level control signal to cooperate, so that the self-capacitance detection unit 750 can output the current self-capacitance value of the signal channel 710 after adding the local capacitance unit 730. When the reset switch rst, the plurality of second switches Φ2 are closed and the plurality of first switches Φ1 are disconnected, the self-capacitance detection unit 750 is in a reset state, and the charge on the feedback capacitor cf of the signal channel 710 is discharged, and the first end of the local capacitor Cb is charged by the capacitor voltage VDD, and the second end is grounded. When the reset switch rst, the plurality of second switches Φ2 are disconnected and the plurality of first switches Φ1 are closed, the self-capacitance detection unit 750 charges the signal channel 710 to the reference voltage VREF, the second end of the local capacitor Cb receives the capacitor voltage VDD, and the first end is connected to the negative input terminal of the self-capacitance detection unit 750, so that the capacitance of the local capacitor Cb is superimposed on the capacitance of the signal channel 710, and the self-capacitance detection unit 750 outputs the corresponding voltage signal CA_out.

[0128] Please refer to Fig.13 , is a schematic diagram of the structure of a third touch chip connected to a signal channel provided in an embodiment of the present application.

[0129] Among them, Fig. 9 Compared with the touch chip in Fig.13 The difference of the touch chip is that it also includes:

[0130] The current mirror unit 760 , the global capacitor unit 720 is connected to each signal channel 710 through the current mirror unit 760 , and the current mirror unit 760 is used to copy the charge of the global capacitor unit 720 to each signal channel 710 .

[0131] In the embodiment of the present application, one global capacitor unit 720 can be multiplexed to each signal channel 710 through the current mirror unit 760, thereby reducing the consumption area of ​​the integrated circuit of the touch control chip.

[0132] Please refer to Fig.14 , Fig.14 A circuit diagram of a global capacitance unit connected to a self-capacitance detection unit provided in an embodiment of the present application.

[0133] Each output terminal of the current mirror unit 760 is connected to the negative input terminal of the voltage comparator of a corresponding self-capacitance detection unit 750 through a first switch Φ1 and a corresponding self-capacitance detection unit 750 .

[0134] The embodiment of the present application also provides a touch device, which is provided with multiple signal channels, which are used to transmit touch signals and complete touch detection, and also includes a touch chip, which is connected to the multiple signal channels in the touch device, and the touch chip also includes: a global capacitor unit, which is used to connect to multiple signal channels; multiple local capacitor units, each local capacitor unit is used to connect to one of the signal channels; a control unit, which is used to connect to each signal channel, the global capacitor unit and each local capacitor unit; the control unit is used to obtain a first self-capacitance value of each signal channel; and adjust the global capacitor unit to a first capacitance value according to all the first self-capacitance values; and control the adjusted global capacitor unit and the self-capacitance of each signal channel to cancel each other's charges; and obtain a second self-capacitance value of each signal channel after charge cancellation; and adjust the local capacitor unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value; and control the adjusted local capacitor unit and the self-capacitance of each signal channel to perform charge superposition or cancellation, thereby correcting the self-capacitance value of the signal channel connected to it to a target reference capacitance value.

[0135] The present application embodiment also provides a computer storage medium, which stores a computer program, and when the computer program is executed by the processor, the processor executes the above-mentioned self-capacitance correction method. In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer storage medium or transmitted through the computer storage medium. The computer instructions can be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital versatile disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0136] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes. In the absence of conflict, the technical features in this embodiment and the implementation scheme can be combined arbitrarily.

[0137] The embodiments described above are merely preferred embodiments of the present application and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements made to the technical solutions of the present application by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present application.

Claims

1. A self-capacitance correction method is applied to a touch chip, wherein the touch chip is connected to multiple signal channels of a touch screen, and the signal channels are used to transmit touch signals and complete touch detection, characterized in that: The touch control chip further includes a global capacitor unit and a plurality of local capacitor units, wherein the global capacitor unit is connected to a plurality of the signal channels, and each of the local capacitor units is connected to one of the signal channels; The global capacitance unit and the local capacitance unit have adjustable capacitance values; The method comprises: Acquire a first self-capacitance value of each of the signal channels; adjusting the global capacitance unit to a first capacitance value according to all the first self-capacitance values; Controlling the adjusted global capacitance unit and the self-capacitance of each signal channel to cancel out charges; Acquire a second self-capacitance value of each of the signal channels after charge cancellation; Adjusting the local capacitance unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value; The local capacitance unit after control adjustment is charged with or offset by the self-capacitance of each signal channel, thereby correcting the self-capacitance value of the signal channel connected thereto to a target reference capacitance value.

2. The self-capacitance calibration method according to claim 1, characterized in that: The obtaining of a first self-capacitance value of each of the signal channels comprises: Adjusting the global capacitance unit to a preset capacitance value; Controlling the adjusted global capacitance unit and the self-capacitance of the signal channel to cancel out charges; Detecting the voltage value of each of the signal channels after charge cancellation; The capacitance value corresponding to the voltage value is used as the first self-capacitance value of each of the signal channels.

3. The self-capacitance calibration method according to claim 1, characterized in that: The global capacitor unit includes M global capacitors connected in parallel, and M switches arranged on the parallel circuit of the global capacitors; The step of adjusting the global capacitance unit to a first capacitance value according to all the first self-capacitance values ​​includes: (a) controlling one of the M switches to be turned on, and the remaining switches of the M switches to be turned off; (b) obtaining a voltage value of each of the signal channels; (c) when it is determined that the voltage value of each of the signal channels is greater than or equal to the preset voltage value, determining that the current switch remains turned on; (d) when it is determined that the voltage value of each of the signal channels is less than the preset voltage value, controlling the current switch to be disconnected; (e) Controlling the next switch of the M switches to be turned on, and executing step (b) until all the on and off states of the M switches are determined, and obtaining the capacitance of the turned-on global capacitor as the first capacitance of the global capacitor unit.

4. The self-capacitance calibration method according to claim 1, wherein: The global capacitor unit includes M global capacitors connected in parallel, and M switches arranged on the parallel circuit of the global capacitors; The step of adjusting the global capacitance unit to a first capacitance value according to all the first self-capacitance values ​​includes: (a) controlling one of the M switches to be turned on, and the remaining switches of the M switches to be turned off; (b) obtaining a voltage value of each of the signal channels; (c) selecting, from all the voltage values, a target voltage value that deviates the most from a preset voltage value; (d) when it is determined that the target voltage value is greater than the preset voltage value, determining that the current switch remains turned on; (e) when it is determined that the target voltage value is less than the preset voltage value, controlling the current switch to be disconnected; (f) Controlling the next switch of the M switches to be turned on, and executing step (b) until all the on and off states of the M switches are determined, and obtaining the capacitance of the turned-on global capacitor as the first capacitance of the global capacitor unit.

5. The self-capacitance calibration method according to claim 1, characterized in that: The obtaining of the second self-capacitance value of each of the signal channels after charge cancellation comprises: Acquiring a voltage value of the signal channel after charge cancellation; The capacitance value corresponding to the voltage value is used as the second self-capacitance value.

6. The self-capacitance calibration method according to claim 5, characterized in that: The step of adjusting the local capacitance unit connected to the corresponding signal channel to a second capacitance value according to the second self-capacitance value includes: Comparing the voltage value with a preset voltage value; When the voltage value is less than the preset voltage value, determining that the local capacitance unit is used for charge superposition, and adjusting the local capacitance unit to a second capacitance value according to a difference between the preset voltage value and the voltage value; When the voltage value is greater than the preset voltage value, determining that the local capacitor unit is used for charge compensation, and adjusting the local capacitor unit to a second capacitance value according to a difference between the voltage value and the preset voltage value; When the voltage value is equal to the preset voltage value, the local capacitance unit is not adjusted.

7. A touch chip connected to a plurality of signal channels in a touch screen, wherein the signal channels are used to transmit touch signals and complete touch detection, characterized in that: The touch control chip also includes: A global capacitor unit, the global capacitor unit is used to connect with the plurality of signal channels; A plurality of local capacitor units, each of the local capacitor units being used to be connected to one of the signal channels; A control unit, the control unit is used to connect with each of the signal channels, the global capacitor unit and each of the local capacitor units; the global capacitor unit and the local capacitor unit have adjustable capacitance values; The control unit is used to obtain the first self-capacitance value of each of the signal channels; and adjust the global capacitance unit to the first capacitance value according to all the first self-capacitance values; and control the adjusted global capacitance unit and the self-capacitance of each of the signal channels to cancel each other out by charge; and obtain the second self-capacitance value of each of the signal channels after charge cancellation; and adjust the local capacitance unit connected to the corresponding signal channel to the second capacitance value according to the second self-capacitance value; and control the adjusted local capacitance unit and the self-capacitance of each of the signal channels to perform charge superposition or cancellation, thereby correcting the self-capacitance value of the signal channel connected thereto to the target reference capacitance value.

8. The touch control chip according to claim 7, characterized in that: Also includes: A plurality of self-capacitance detection units, each of which is used to be connected to one of the signal channels, or each of which is used to be connected to one of the signal channels in a time-sharing manner, and each of which is connected to the control unit; The self-capacitance detection unit is used to detect the self-capacitance value of the signal channel connected thereto, convert the self-capacitance value into a voltage value, and transmit the voltage value to the control unit; The self-capacitance detection unit includes a voltage comparator, a feedback capacitor and a reset switch, wherein the negative input terminal of the voltage comparator is connected to the signal channel, one end of the feedback capacitor is connected to the negative input terminal of the voltage comparator, and the other end is connected to the output terminal of the voltage comparator, one end of the reset switch is connected to the negative input terminal of the voltage comparator, and the other end is connected to the output terminal of the voltage comparator, and the positive input terminal of the voltage comparator is connected to a reference voltage.

9. The touch control chip according to claim 8, characterized in that: The local capacitor unit includes a local capacitor with adjustable capacitance, a first switch group and a second switch group, wherein the first switch group and the second switch group are arranged on a circuit connecting the local capacitor and one of the signal channels; The first switch group includes three first switches, and the second switch group includes three second switches, wherein one end of one of the second switches is connected to the signal channel and the other end is grounded; the first end of the local capacitor is connected to the negative input end of the voltage comparator through two first switches, and receives the capacitor voltage through a second switch, the two first switches are both connected to the signal channel, the second end of the local capacitor is grounded through one of the second switches, and receives the capacitor voltage through one of the first switches.

10. The touch control chip according to claim 8, characterized in that: Also includes: A current mirror unit, wherein the global capacitor unit is connected to each of the signal channels via the current mirror unit, and the current mirror unit is used to copy the charge of the global capacitor unit to each of the signal channels.

11. The touch control chip according to claim 7, characterized in that: The global capacitor unit includes M global capacitors connected in parallel and M global capacitor switches arranged on the parallel circuit of the global capacitors.

12. A touch device, wherein a plurality of signal channels are provided in the touch device, wherein the signal channels are used to transmit touch signals and complete touch detection, and further comprising a touch chip, wherein the touch chip is connected to the plurality of signal channels in the touch device, wherein: The touch control chip also includes: A global capacitor unit, the global capacitor unit is used to connect with the plurality of signal channels; A plurality of local capacitor units, each of the local capacitor units being used to be connected to one of the signal channels; A control unit, the control unit is used to connect with each of the signal channels, the global capacitor unit and each of the local capacitor units; the global capacitor unit and the local capacitor unit have adjustable capacitance values; The control unit is used to obtain the first self-capacitance value of each of the signal channels; and adjust the global capacitance unit to the first capacitance value according to all the first self-capacitance values; and control the adjusted global capacitance unit and the self-capacitance of each of the signal channels to cancel each other out by charge; and obtain the second self-capacitance value of each of the signal channels after charge cancellation; and adjust the local capacitance unit connected to the corresponding signal channel to the second capacitance value according to the second self-capacitance value; and control the adjusted local capacitance unit and the self-capacitance of each of the signal channels to perform charge superposition or cancellation, thereby correcting the self-capacitance value of the signal channel connected thereto to the target reference capacitance value.

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