Touch detection method, touch chip and electronic device

Abstract

A touch detection method, a touch chip (1) and an electronic device. The touch detection method comprises: applying a driving signal encoded based on a preset encoding mode to a driving channel (TX1, TX2, TX3, TX4) of a touch screen; wherein the encoding mode comprises: dividing a plurality of signal waveforms of the driving signal into waveforms of at least one correlated double sampling period, and the same correlated double sampling period contains two sampling periods (101) with a phase difference of 180° between the waveforms; receiving a sensing signal (102) corresponding to the driving signal from a sensing channel (RX1, RX2, RX3, RX4) of the touch screen; and determining touch position information (103) according to the sensing signal and the encoding information corresponding to the encoding mode. The technical solution can improve the ability to resist low-frequency interference in touch detection, thereby improving the signal-to-noise ratio of the system and enhancing the touch sensitivity.

Description

Touch detection methods, touch chips and electronic devices

[0001] This application is a divisional application of the patent application filed on December 17, 2018, with application number 201880002876.6 and invention title "Touch Detection Method, Touch Chip and Electronic Device". Technical Field

[0002] This application relates to the field of touch technology, and in particular to a touch detection method, a touch chip, and an electronic device. Background Technology

[0003] Existing capacitive touchscreens typically employ multi-channel encoding detection or single-channel detection methods for touch detection. When a finger touches the screen, the capacitance value at the corresponding capacitive sensing node changes. By detecting this capacitance change in real time, the touch chip can determine the corresponding touch location and generate the appropriate touch event.

[0004] The inventors have discovered that the existing technology has at least the following problems: the existing multi-channel coding detection method or single-channel detection method is easily affected by low-frequency interference, resulting in low sensitivity of touch detection. Summary of the Invention

[0005] The purpose of some embodiments of this application is to provide a touch detection method, a touch chip, and an electronic device that can improve the ability to resist low-frequency interference in touch detection, thereby improving the signal-to-noise ratio of the system and enhancing touch sensitivity.

[0006] This application provides a touch detection method, comprising: applying a drive signal encoded based on a preset encoding method to a drive channel of a touch screen; wherein the encoding method includes dividing multiple signal waveforms of the drive signal into waveforms of at least one correlated double sampling period, wherein the same correlated double sampling period includes two sampling periods in which the waveforms are 180° out of phase; receiving a sensing signal corresponding to the drive signal from a sensing channel of the touch screen; and determining touch position information based on the sensing signal and the encoding information corresponding to the encoding method.

[0007] This application embodiment also provides a touch chip, including: a driving unit, which applies a driving signal encoded based on a preset encoding method to the driving channel of a touch screen; wherein the encoding method includes dividing multiple signal waveforms of the driving signal into waveforms of at least one correlated double sampling period, and the same correlated double sampling period includes two sampling periods with waveform phases differing by 180°; a receiving unit, which receives a sensing signal corresponding to the driving signal from the sensing channel of the touch screen; and a processing unit, which determines touch position information based on the sensing signal and the encoding information corresponding to the encoding method.

[0008] Embodiments of the present invention also provide an electronic device, including: a touch screen and the above-described touch chip.

[0009] Compared to existing technologies, the embodiments of this application divide the multiple signal waveforms of the driving signal into waveforms of at least one correlated double sampling period. The same correlated double sampling period includes two sampling periods with a waveform phase difference of 180°. Those skilled in the art should understand that touch detection time is relatively short, and low-frequency interference can be considered to remain constant during touch detection. Furthermore, those skilled in the art should also understand that the sensing signal includes the target signal (i.e., the coupled signal of the driving signal) and low-frequency interference. The target signal has a phase shift relative to the driving signal, and the waveform phase of the target signal and the waveform phase of the driving signal at the same moment always maintain this phase shift difference. In this embodiment, since the phase difference of the driving signal in the two sampling periods of a correlated double sampling period is 180°, the phase difference of the target signal in the sensing signal sampled in the two sampling periods also remains at 180°, and the phase of the low-frequency interference is the same. Therefore, by calculation, the low-frequency interference in the two sampling periods of the same correlated double sampling period can be canceled out; thereby improving the ability to resist low-frequency interference in touch detection, thus improving the system's signal-to-noise ratio and enhancing touch sensitivity.

[0010] Furthermore, the two sampling periods within the same correlated double sampling period contain an equal number of signal periods; wherein one signal period corresponds to one signal waveform. In this embodiment, the equal number of signal periods in the two sampling periods means that the waveforms of the two sampling periods are waveforms of equal duration, which allows the low-frequency interference contained in the waveforms of the two sampling periods to be canceled out as completely as possible.

[0011] Furthermore, the multiple signal waveforms are divided into a waveform with a coherent double sampling period. This embodiment provides a specific implementation method.

[0012] Furthermore, the plurality of signal waveforms are divided into several correlated double sampling periods, and the number of signal periods contained in each of the correlated double sampling periods is equal; moreover, the number of signal periods contained in each of the correlated double sampling periods is 1. This embodiment provides another specific implementation method; for the same driving signal (containing the same number of signal waveforms), the more correlated double sampling periods it is divided into, the more accurately low-frequency interference in the sensing signal can be canceled during the calculation of touch position information; that is, the stronger the ability to resist low-frequency interference. Attached Figure Description

[0013] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0014] Figure 1 is a flowchart of a touch detection method according to a first embodiment of this application;

[0015] Figure 2 is a schematic diagram of a touch screen that can be touched using the touch detection method of the first embodiment;

[0016] Figure 3 is a detailed flowchart of the touch detection method according to the first embodiment of this application;

[0017] Figure 4 is a schematic diagram of the encoded information when the touch screen in Figure 2 is detected using the traditional encoding method.

[0018] Figure 5 is a waveform diagram of the driving signal corresponding to the encoded information in Figure 4;

[0019] Figure 6 is a schematic diagram of the encoding information corresponding to the encoding method in the touch detection method according to the first embodiment of this application;

[0020] Figure 7 is a waveform diagram of the driving signal corresponding to the encoded information in Figure 6;

[0021] Figure 8 is a waveform diagram of the driving signal corresponding to the encoded information in the touch detection method according to the second embodiment of this application;

[0022] Figure 9 is a schematic diagram of the encoded information when the driving signal is divided into four related double sampling periods in the touch detection method according to the second embodiment of this application;

[0023] Figure 10 is a waveform diagram of the driving signal corresponding to the encoded information in the touch detection method according to the third embodiment of this application;

[0024] Figure 11 is a block diagram of a touch chip according to a fourth embodiment of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, some embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0026] The first embodiment of this application relates to a touch detection method, as shown in FIG1, including the following steps:

[0027] Step S101: Apply a drive signal encoded based on a preset encoding method to the drive channel of the touch screen; wherein, the encoding method includes dividing multiple signal waveforms of the drive signal into waveforms of at least one correlated double sampling period, and the same correlated double sampling period includes two sampling periods with waveforms phased by 180°.

[0028] Step S102: Receive the sensing signal corresponding to the driving signal from the sensing channel of the touch screen;

[0029] Step S103: Determine the touch position information based on the sensing signal and the encoding information corresponding to the encoding method.

[0030] Compared to existing technologies, this embodiment divides the multiple signal waveforms of the driving signal into waveforms of at least one correlated double sampling period. Each correlated double sampling period contains two sampling periods with a waveform phase difference of 180°. Those skilled in the art should understand that touch detection time is relatively short, and low-frequency interference can be considered to remain constant during touch detection. Furthermore, those skilled in the art should also understand that the sensing signal includes the target signal (i.e., the coupled signal of the driving signal) and low-frequency interference. The target signal has a phase shift relative to the driving signal, and the waveform phase of the target signal and the waveform phase of the driving signal at the same moment always maintain this phase shift difference. In this embodiment, since the phase difference of the driving signal in the two sampling periods of a correlated double sampling period is 180°, the phase difference of the target signal in the sensing signal sampled in the two sampling periods also remains at 180°, and the phase of the low-frequency interference is the same. Therefore, by calculation, the low-frequency interference in the two sampling periods of the same correlated double sampling period can be canceled out; thereby improving the ability to resist low-frequency interference in touch detection, thus improving the system's signal-to-noise ratio and enhancing touch sensitivity.

[0031] The implementation details of the touch detection method in this embodiment are described below. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0032] The touch detection method of this embodiment can be used to perform touch detection on mutual capacitive or self-capacitive touchscreens. Figure 2 shows a schematic diagram of a touchscreen that can be touched using the touch detection method of this embodiment. The touchscreen in Figure 2 includes a driving layer and a sensing layer (not shown); the driving layer includes four driving channels arranged parallel to each other along a first direction, and the sensing layer includes four sensing channels arranged parallel to each other along a second direction. In this embodiment, the first direction and the second direction are perpendicular; a coupling capacitor C is formed at the intersection of each driving channel and each sensing channel. ij Where 1≤i≤4, 1≤j≤4, and i and j are both positive numbers; coupling capacitor C ijThe size of the intersection indicates the touch status at the touch position. Four driving channels and four sensing channels are connected to the touch chip; the touch chip applies driving signals to the driving channels and receives sensing signals from the sensing channels. This embodiment and the following embodiments use the touchscreen in Figure 2 as an example for illustration; however, it should be noted that Figure 2 only illustrates a 4*4 mutual capacitive touchscreen, but this application embodiment does not impose any limitation on the number of driving channels and sensing channels included in the touchscreen; furthermore, the touch detection method of this application embodiment can also be applied to self-capacitive touchscreens, where the driving channel and sensing channel are the same channel.

[0033] In step S101, the drive signal applied to the drive channel lasts for at least one preset time period, or it may last for multiple preset time periods. The drive signal within each preset time period includes multiple signal waveforms. That is, the multiple signal waveforms of the drive signal are divided into waveforms with at least one correlated double sampling period. The same correlated double sampling period contains two sampling periods with a waveform phase difference of 180°. This can be understood as dividing the multiple signal waveforms of the drive signal within a preset time period into waveforms with at least one correlated double sampling period, where the same correlated double sampling period contains two sampling periods with a waveform phase difference of 180°.

[0034] It should be noted that in the example of Figure 2, since there are only 4 driving channels, driving signals are applied to all 4 driving channels simultaneously. That is, based on the example of Figure 2, the encoding method of the touch detection method can be formed by combining full-channel encoding and the correlated double sampling principle. However, this embodiment does not impose any restrictions on this. In other examples, the encoding method can be formed by combining multi-channel encoding and the correlated double sampling principle, or it can be formed by combining single-channel encoding and the correlated double sampling principle. For example, for a 16*16 mutual capacitance touch screen, the 16 driving channels can be applied with driving signals in groups of 4 (that is, formed by combining multi-channel encoding and the correlated double sampling principle).

[0035] In step S102, the touch chip receives sensing signals from the sensing channels while applying driving signals to the driving channels. Corresponding to Figure 2, the touch chip applies driving signals to all four driving channels simultaneously and receives sensing signals from the four sensing channels while applying the driving signals.

[0036] As shown in Figure 3, step S103 includes the following sub-steps:

[0037] Sub-step S1031 involves converting the induction signal from analog to digital to obtain a digital induction signal.

[0038] Specifically, the sensing signal and the driving signal have the same signal period. First, the signal waveform of the sensing signal with multiple signal periods is digitally converted to obtain the digital signal corresponding to the multiple signal waveforms, which is the digital form of the sensing signal. For example, if the driving signal contains a signal waveform with 2N signal periods, then the sensing signal also contains a signal waveform with 2N signal periods.

[0039] Sub-step S1032 demodulates the digital form of the inductive signal and obtains demodulated information; wherein the waveform of each sampling period corresponds to a demodulated value in the demodulated information.

[0040] Specifically, the aforementioned sampling period is the sampling period of the induced signal. During demodulation, the induced signal is sampled according to the sampling period, so that the waveform of each sampling period can obtain a demodulated value. Assuming that one sampling period contains x signal periods, the waveform of x signal periods can be demodulated to obtain a demodulated value; where x is an integer greater than or equal to 1. For each induction channel, the waveform of each relevant double sampling period in the received induced signal can obtain two demodulated values, that is, the induced signal received by each induction channel can contain at least two demodulated values; therefore, the demodulated information contains multiple demodulated values, and multiple demodulated values ​​can form a demodulation matrix R, that is, the demodulated information can be represented by the demodulation matrix R. In this embodiment, orthogonal demodulation is used for demodulation, but it is not limited to this.

[0041] Sub-step S1033: Calculate the touch position information based on the demodulation information and the encoding information corresponding to the encoding method.

[0042] Specifically, touch position information can be characterized by the capacitance value of the coupling capacitor Cij (as mentioned above, the coupling capacitor Cij is formed at the intersection of each driving channel and each sensing channel). ij The capacitance values ​​of multiple coupling capacitors Cij can form a capacitance matrix C, meaning that touch position information can be represented by the capacitance matrix C.

[0043] In this embodiment, the preset encoding information within the touch chip corresponds to the encoding method. Specifically, the encoding information includes multiple encoding values, each representing the phase of the driving signal applied to a certain driving channel within a certain sampling period. Multiple encoding values ​​can form an encoding matrix A, meaning the encoding information can be represented by encoding matrix A. Those skilled in the art should know that the demodulation matrix R = AC, therefore, the capacitance matrix C = A. -1 R, thus allowing the calculation of touch position information.

[0044] The following section compares the touch detection method in this embodiment with the traditional touch detection method based on the touchscreen shown in Figure 2, to more intuitively illustrate the differences between the two.

[0045] Figure 4 shows a schematic diagram of the encoding information when performing touch detection on the touchscreen in Figure 2 using a traditional encoding detection method. The encoding information in Figure 4 reflects the phase changes of the driving signal over different time periods. In Figure 4, the horizontal axis represents driving channels TX1 to TX4, and the vertical axis represents four preset time periods T0 to T4. As shown in the encoding information in Figure 4, each group of driving channels is assigned four consecutive time periods T0 to T4 to apply the driving signal. In this embodiment, the durations of the four time periods T0 to T4 are all equal; however, this is not a limitation.

[0046] The waveform of the driving signal can be, for example, a sine wave. "+" indicates that the sine wave starts with a phase of 0°, called a positive code; "-" indicates that the sine wave starts with a phase of 180°, called a negative code. The driving signal applied to the driving channel within each time period is either a positive code or a negative code. Furthermore, the driving signal applied within each time period contains multiple signal cycles of sine waves, and the starting phases of the sine waves in each signal cycle are the same (both positive codes or both negative codes). It should be noted that while "+" indicates a sine wave starting with a phase of 0° and "-" indicates a sine wave starting with a phase of 180°, this is not a limitation. In other examples, "-" can also represent a sine wave starting with a phase of 0° and "+" can represent a sine wave starting with a phase of 180°; or, the positive and negative codes do not necessarily have to be 0° and 180° respectively, and can be other degrees, as long as the phase difference between the positive and negative codes is 180°. In addition, the waveform of the driving signal is not limited to a sine wave; it can also be a square wave, a triangle wave, etc.

[0047] Figure 5 shows a waveform diagram of the driving signal in Figure 4. Figure 5 illustrates the waveform of the driving signal within time period T3. As shown in Figure 5, time period T3 contains 2N signal cycles of sine waves. In this embodiment, the duration of each time period is equal, that is, each time period contains 2N signal cycles of waveforms, where N is an integer greater than or equal to 1. As shown in the encoding information in Figure 4, the driving signals applied to driving channels TX1, TX2, TX3, and TX4 within time period T3 are "+", "+", "+", and "-", respectively. The signal waveforms above driving channels TX1, TX2, TX3, and TX4 in Figure 5 represent the signal waveforms of the driving signals applied to driving channels TX1, TX2, TX3, and TX4, respectively. It can be seen that for the three driving channels TX1, TX2, and TX3, the starting phase of each sine wave in the driving signal is 0°, and for the driving channel TX4, the starting phase of each sine wave in the driving signal is 180°.

[0048] As shown below, the encoding matrix A can represent the encoding information of TX1 to TX4 in the traditional encoding detection method mentioned above; the encoding matrix A includes multiple encoding values ​​Aij (i.e., A11, A12, A13, A14, A21, A22...), where i in Aij represents the time period and j represents the j-th TX channel, and the value range of i and j in Aij is 0≤i≤3, 1≤j≤4;

[0049]

[0050] In this example, the drive signal is "+", and the corresponding code value is "1"; the drive signal is "-", and the corresponding code value is "-1"; the specific value of A is as follows:

[0051]

[0052] In the capacitance matrix C, Cij (i.e., C11, C12, C13, C14, C21, C22...) represents the coupling capacitance C formed at the intersection of each driving channel and each sensing channel in Figure 1. ij The capacitance value, and the range of values ​​for i and j in Cij is 0≤i≤3, 1≤j≤4;

[0053]

[0054] The demodulation matrix R represents the demodulated information:

[0055]

[0056] The demodulation matrix R contains multiple demodulation values ​​Rij (i.e., R01, R02, R03, R04, R11, R12, R13, R14, ...), where i represents the time period and j represents the j-th RX drive channel. The values ​​of i and j in Rij are 0 ≤ i ≤ 3 and 1 ≤ j ≤ 4. Each sensing channel corresponds to a demodulation value for its sensing signal in each time period. For example, sensing channel RX1 corresponds to R01, R02, R03, and R04 in time periods T0, T1, T2, and T3, respectively.

[0057] Since the demodulation matrix R = AC,

[0058] Therefore, the capacitance matrix C = A can be obtained. -1 R.

[0059] The capacitance matrix C represents the detected touch position information of the touch screen in Figure 2.

[0060] Figure 6 shows the encoding information corresponding to the encoding method in the touch detection method of this embodiment; Figure 7 shows the waveform diagram of the driving signal corresponding to the encoding information in Figure 6, wherein the waveform of the driving signal in time period T3 is shown in Figure 7.

[0061] In this embodiment, the 2N signal cycles within each time period are divided into a correlated double sampling period, which contains two sampling periods with the same number of signal cycles. That is, the first N signal cycles out of the 2N signal cycles are taken as one sampling period, and the last N signal cycles are taken as another sampling period, with the waveforms of the two sampling periods differing by 180° in phase. As shown in Figures 6 and 7, the 2N signal cycles in time period T3 form a correlated double sampling period, and the two sampling periods contained in this correlated double sampling period correspond to sub-time periods 31 and 32, respectively. It should be emphasized that since the number of signal cycles in the two sampling periods is equal, the durations of sub-time periods 31 and 32 are equal; the waveforms in sub-time periods 31 and 32 differ by 180° in phase.

[0062] The encoded information contains multiple encoded values, each of which represents the phase of the driving signal applied to a certain driving channel within a certain sampling period. Since each sampling period corresponds to each sub-time period, it can also be understood that each encoded value represents the phase of the driving signal applied to a certain driving channel within a certain sub-time period. For example, within time period T3, the drive signal of drive channel TX1 changes from "+" to "+" and "-" (corresponding to time periods 31 and 32 respectively), and the corresponding encoded value in the encoding matrix changes from "1" to "1" and "-1" (corresponding to time periods 31 and 32 respectively); the drive signal of drive channel TX2 changes from "+" to "+" and "-" (corresponding to time periods 31 and 32 respectively), and the corresponding encoded value in the encoding matrix changes from "1" to "1" and "-1" (corresponding to time periods 31 and 32 respectively); the drive signal of drive channel TX3 changes from "+" to "+" and "-" (corresponding to time periods T31 and T32 respectively), and the corresponding encoded value in the encoding matrix changes from "1" to "1" and "-1" (corresponding to time periods 31 and 32 respectively); the drive signal of drive channel TX4 changes from "-" to "-" and "+" (corresponding to time periods T31 and T32 respectively), and the corresponding encoded value in the encoding matrix changes from "1" to "1" and "-1" (corresponding to time periods 31 and 32 respectively). Similarly, time period T0 is divided into sub-time periods 01 and 02, time period T1 is divided into sub-time periods 11 and 12, and time period T2 is divided into sub-time periods 21 and 22; the driving signal and the encoded values ​​in the encoding matrix are also changed accordingly. That is, in this embodiment, the encoded information in Figure 6 is derived from the encoded information in Figure 4. Specifically, the "+" in Figure 4 becomes "+" and "-" (corresponding to two sampling periods in a correlated double sampling period), and the "-" in Figure 4 becomes "-" and "+" (corresponding to two sampling periods in a correlated double sampling period).

[0063] It should also be noted that in this embodiment, in the tabular encoding information of Figures 4 and 6, "+" and "-" are used to represent the phase of the driving signal as 0° and 180°, respectively. However, in the actual calculation, the tabular encoding information can be converted into matrix encoding information, i.e., the encoding matrix. The encoding value "1" in the encoding matrix is ​​opposite to "+" in the encoding information, and the encoding value "-1" in the encoding matrix is ​​opposite to "-" in the encoding information. That is, when converting the tabular encoding information in Figures 4 and 6 into the encoding matrix, "+" is represented by "1" and "-" is represented by "-1".

[0064] The encoding matrix A′ contains multiple encoding values ​​A′ij (i.e., A′011, A′012, A′013, A′014, A′021, A′022, etc.), which represent the encoding information corresponding to the driving channels TX1 to TX4 in the encoding method of this embodiment; i in A′ij represents the sub-time period, j represents the j-th TX channel, and the value range here is i = 01, 02, 11, 12, 21, 22, 31, 32, j = 1, 2, 3, 4;

[0065]

[0066] In this example, the specific value of A′ is as follows:

[0067]

[0068] The demodulation matrix R' contains multiple demodulation values ​​R'ij (i.e., R'011, R'012, R'013, R'014, R'021, R'022, etc.), where i represents the sub-time period and j represents the j-th RX channel. The values ​​of i and j in R'ij are i = 01, 02, 11, 12, 21, 22, 31, 32, and j = 1, 2, 3, 4. The demodulation matrix R' is represented as:

[0069]

[0070] Capacitor matrix C' = A' -1 R', obtains the touch location information.

[0071] In this embodiment, those skilled in the art should know that the received sensing signal includes low-frequency interference and a target signal coupled from the driving signal; the signal period of the sensing signal is the same as that of the driving signal, and the target signal has a phase shift relative to the driving signal, and the waveform phase of the target signal and the waveform phase of the driving signal at the same moment always maintain this phase shift difference. For example, in the above example, the signal period of the sine wave is 10us (i.e., the frequency of the driving signal is 100kHz), then the signal period of the sensing signal is also 10us; in a correlated double sampling period, the waveform phases of the two sampling periods of the driving signal are 0° and 180°, respectively, then corresponding to these two sampling periods, the waveform of the target signal undergoes a phase shift of, for example, 30° (this is just an example, the phase shift is not limited to 30°, and needs to be determined according to the actual situation), that is, the waveform phases of the target signal corresponding to these two sampling periods are 30° and 210°, respectively, so the waveform phase difference of the target signal in these two sampling periods still remains 180°; and since the touch detection time is relatively short, it can be considered that the low-frequency interference remains unchanged during the touch detection process, that is, the phase of the low-frequency interference remains unchanged. Assuming the target signal is S and the low-frequency interference is D within one sampling period of the induced signal, then in a correlated double sampling period, if the driving signals corresponding to the two sampling periods are positive and negative respectively, the demodulated values ​​of the induced signals in the two sampling periods can be expressed as S+D and -S+D respectively. Therefore, the induced signal in one correlated double sampling period, after subtraction, can be obtained as: (-S+D)-(S+D)=-2S, thus the target signal S can be calculated. That is, the target signal can be obtained relatively accurately by canceling the low-frequency interference. In the process of solving the demodulated value in this embodiment, the low-frequency interference is canceled out using the above subtraction method, so the final data can be considered to contain only the target signal S. Since the "+" or "-" of each encoded value in the encoding matrix A′ is determined by whether the driving signal in each sub-time period is positive or negative, the demodulated value R'ij in the demodulation matrix is ​​S+D or -S+D. Therefore, the capacitance matrix C'=A' -1 R', the matrix operation here includes the process of canceling out low-frequency interference by subtraction as described above.

[0072] It should be noted that in the specific example of this embodiment, the two sampling periods within the same correlated double sampling period contain an equal number of signal periods. This allows the low-frequency interference contained in the waveforms of the two sampling periods to be canceled out as completely as possible. However, this embodiment is not limited to this; the two sampling periods within the same correlated double sampling period may contain unequal numbers of signal periods. Furthermore, in practice, due to environmental or other unpredictable factors, regardless of whether the two sampling periods contain an equal number of signal periods, the low-frequency interference in the two sampling periods may not be completely identical. However, the touch detection method of this embodiment can still cancel out at least some of the low-frequency interference, improving the system's signal-to-noise ratio.

[0073] The second embodiment of this application relates to a touch detection method. This embodiment is largely the same as the first embodiment, with the main difference being that: in the first embodiment, multiple signal waveforms of the driving signal are divided into a correlated double sampling period; while in this embodiment, multiple signal waveforms of the driving signal are divided into multiple correlated double sampling periods, and the number of signal periods contained in the sampling period of each correlated double sampling period is 1.

[0074] Figure 8 shows a waveform diagram of the driving signal corresponding to the encoded information in the touch detection method of the second embodiment. In Figure 8, as in the first embodiment, the driving signal also contains 2N signal waveforms (i.e., 2N signal periods). The 2N signal waveforms are divided into N correlated double sampling periods, and the number of signal periods contained in the two sampling periods in each correlated double sampling period is 1. The larger the value of N, the more correlated double sampling periods there are.

[0075] Figure 9 illustrates the encoded information when N equals 4. The time period T0 is divided into four sub-time periods: 01, 02, 03, and 04. Similarly, time periods T1, T2, and T3 are each divided into four sub-time periods.

[0076] This embodiment provides a specific implementation of the touch detection method; for the same driving signal (containing the same number of signal waveforms), the more related double sampling periods are divided, the more accurately the low-frequency interference in the sensing signal can be canceled during the calculation of touch position information; that is, the stronger the ability to resist low-frequency interference.

[0077] The third embodiment of this application relates to a touch detection method. This embodiment is largely the same as the second embodiment, with the main difference being that in the second embodiment, the number of signal cycles contained in the two sampling cycles of each correlated double sampling period is 1; while in this embodiment, the number of signal cycles contained in the two sampling cycles of each correlated double sampling period is greater than 1.

[0078] Figure 10 shows a waveform diagram of the driving signal corresponding to the encoded information in the touch detection method of the third embodiment. Similar to the second embodiment, the driving signal also contains 2N signal waveforms (i.e., 2N signal cycles). These 2N signal waveforms are, for example, divided into 4 correlated double sampling cycles. The two sampling cycles in each correlated double sampling cycle contain an equal number of signal cycles, which is N / 4. In this example, N is an even number greater than or equal to 8. For example, if N = 16, then each sampling cycle contains 4 signal cycles (as shown in Figure 10, 4 Cycles). It should be noted that, due to the large number of signal cycles in each sampling cycle and the correlated double sampling cycles, to more clearly illustrate the waveform, Figure 10 only shows the waveform of the driving channel TX1 in the third time period T3; the schematic diagram of the encoded signal in this example can be found in Figure 9.

[0079] It should be noted that in this embodiment, the number of signal periods contained in the two sampling periods of each correlated double sampling period is equal, but this is not a limitation; it is also possible that the number of signal periods contained in the two sampling periods of the same correlated double sampling period is equal, while the number of signal periods contained in the sampling periods of different correlated double sampling periods is not equal.

[0080] The fourth embodiment of this application relates to a touch chip, as shown in FIG11, the touch chip 1 includes:

[0081] The driving unit 11 applies a driving signal encoded based on a preset encoding method to the driving channel of the touch screen; wherein the encoding method includes dividing multiple signal waveforms of the driving signal into waveforms of at least one correlated double sampling period, and the same correlated double sampling period includes two sampling periods in which the waveforms are 180° out of phase.

[0082] The receiving unit 12 is used to receive the sensing signal corresponding to the driving signal from the sensing channel of the touch screen. The receiving unit 12 can be understood as including a signal conditioning circuit, which may include signal amplification, signal filtering, etc.; that is, the receiving unit 12 can perform some preprocessing on the sensing signal.

[0083] The processing unit 13 determines the touch position information based on the sensing signal and the encoding information corresponding to the encoding method.

[0084] Specifically, the processing unit 13 includes:

[0085] The analog-to-digital conversion subunit 131 is used to convert the induction signal from analog to digital and obtain the induction signal in digital form.

[0086] The demodulation subunit 132 is used to demodulate the digital form of the sensed signal and obtain demodulated information; wherein, the waveform of each sampling period corresponds to a demodulated value in the demodulated information;

[0087] The calculation subunit 133 is used to calculate the touch position information based on the demodulation information and the encoding information corresponding to the encoding method;

[0088] Storage subunit 134 is used to store the encoding information corresponding to the encoding method.

[0089] In this embodiment, the driving unit 11 is connected to the analog-to-digital conversion subunit 131 in the processing unit 13, and is used to synchronize the analog-to-digital conversion subunit 131. That is, when the driving unit 11 applies a driving signal to the driving channel, it controls the analog-to-digital conversion subunit 131 to synchronously acquire the digital form of the sensing signal. In another example, the driving unit 11 can be connected to both the analog-to-digital conversion subunit 131 and the receiving unit 12, that is, the driving unit 11 can synchronize both the analog-to-digital conversion subunit 131 and the receiving unit 12.

[0090] Compared to existing technologies, the embodiments of this application divide the multiple signal waveforms of the driving signal into waveforms of at least one correlated double sampling period. The same correlated double sampling period includes two sampling periods with a waveform phase difference of 180°. Those skilled in the art should understand that touch detection time is relatively short, and low-frequency interference can be considered to remain constant during touch detection. Furthermore, those skilled in the art should also understand that the sensing signal includes the target signal (i.e., the coupled signal of the driving signal) and low-frequency interference. The target signal has a phase shift relative to the driving signal, and the waveform phase of the target signal and the waveform phase of the driving signal at the same moment always maintain this phase shift difference. In this embodiment, since the phase difference of the driving signal in the two sampling periods of a correlated double sampling period is 180°, the phase difference of the target signal in the sensing signal sampled in the two sampling periods also remains at 180°, and the phase of the low-frequency interference is the same. Therefore, by calculation, the low-frequency interference in the two sampling periods of the same correlated double sampling period can be canceled out; thereby improving the ability to resist low-frequency interference in touch detection, thus improving the system's signal-to-noise ratio and enhancing touch sensitivity.

[0091] It is not difficult to see that this embodiment is a device embodiment corresponding to any of the first to third embodiments, and this embodiment can be implemented in conjunction with any of the first to third embodiments. The relevant technical details mentioned in any of the first to third embodiments are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to any of the first to third embodiments.

[0092] The fifth embodiment of this application relates to an electronic device, including a touch screen and the touch chip described in the fourth embodiment above.

[0093] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A touch detection method, characterized in that, include: A drive signal encoded according to a preset encoding method is applied to at least one drive channel of a touchscreen; wherein the drive signal lasts for at least a preset time period, and each time period contains multiple signal waveforms; the encoding method includes dividing the multiple signal waveforms of the drive signal applied to the same drive channel within the same time period into waveforms of at least one correlated double sampling period, wherein the same correlated double sampling period contains two sampling periods with waveform phases differing by 180°; a sensing signal corresponding to the drive signal is received from a sensing channel of the touchscreen; touch position information is determined according to the sensing signal and the encoding information corresponding to the encoding method; wherein the drive channel is arranged parallel to a first direction, the sensing channel is arranged parallel to a second direction, and the first direction and the second direction are perpendicular; wherein the preset encoding method corresponds to an encoding matrix, the encoding matrix being used to determine the phase of the drive signal applied to multiple drive channels within multiple consecutive time periods; determining the touch position information according to the sensing signal and the encoding information corresponding to the encoding method includes: determining the touch position information by calculating the product of the inverse matrix of the encoding matrix and the demodulation matrix corresponding to the sensing signal.

2. The touch detection method according to claim 1, characterized in that, The two sampling periods in the same correlated double sampling period contain an equal number of signal periods; wherein one signal period corresponds to one signal waveform.

3. The touch detection method according to claim 1 or 2, characterized in that, The multiple signal waveforms are divided into a waveform with a corresponding double sampling period.

4. The touch detection method according to claim 2, characterized in that, The plurality of signal waveforms are divided into several waveforms of the associated double sampling periods, and the number of signal periods contained in each of the associated double sampling periods is equal.

5. The touch detection method according to claim 4, characterized in that, The number of signal periods contained in each of the aforementioned related double sampling periods is 1.

6. The touch detection method according to claim 1, characterized in that, The step of determining the touch position information based on the sensing signal and the encoding information corresponding to the encoding method includes: performing analog-to-digital conversion on the sensing signal to obtain the sensing signal in digital form; demodulating the sensing signal in digital form to obtain demodulation information; wherein the waveform of each sampling period corresponds to a demodulation value in the demodulation information; and calculating the touch position information based on the demodulation information and the encoding information corresponding to the encoding method.

7. The touch detection method according to claim 1, characterized in that, The touchscreen includes a driving layer and a sensing layer. The driving layer includes a plurality of driving channels arranged parallel to each other along a first direction, and the sensing layer includes a plurality of sensing channels arranged parallel to each other along a second direction.

8. The touch detection method according to claim 1, characterized in that, The number of drive channels to which the drive signal is applied is the same as the number of time periods during which the drive signal is sustained.

9. A touch chip, characterized in that, include: A driving unit applies a driving signal encoded based on a preset encoding method to at least one driving channel of a touchscreen; wherein the driving signal lasts for at least a preset time period, and the driving signal within each time period includes multiple signal waveforms; the encoding method includes dividing the multiple signal waveforms of the driving signal applied to the same driving channel within the same time period into waveforms of at least one correlated double sampling period, and the same correlated double sampling period includes two sampling periods with waveforms phased by 180°; a receiving unit is configured to receive a sensing signal corresponding to the driving signal from a sensing channel of the touchscreen; a processing unit determines touch position information based on the sensing signal and the encoding information corresponding to the encoding method; wherein the driving channel is arranged parallel to a first direction, the sensing channel is arranged parallel to a second direction, and the first direction and the second direction are perpendicular; wherein the driving unit is configured to apply a driving signal to multiple driving channels within multiple consecutive time periods based on the preset encoding method defined by an encoding matrix; the processing unit is configured to determine the touch position information by calculating the product of the inverse matrix of the encoding matrix and the demodulation matrix corresponding to the sensing signal.

10. The touch chip according to claim 9, characterized in that, The two sampling periods in the same correlated double sampling period contain an equal number of signal periods; wherein one signal period corresponds to one signal waveform.

11. The touch chip according to claim 9 or 10, characterized in that, The multiple signal waveforms are divided into a waveform with a corresponding double sampling period.

12. The touch chip according to claim 10, characterized in that, The plurality of signal waveforms are divided into several waveforms of the associated double sampling periods, and the number of signal periods contained in each of the associated double sampling periods is equal.

13. The touch chip according to claim 12, characterized in that, The number of signal periods contained in each of the aforementioned related double sampling periods is 1.

14. The touch chip according to claim 9, characterized in that, The processing unit includes: an analog-to-digital conversion subunit for converting the sensing signal from analog to digital to obtain the sensing signal in digital form; a demodulation subunit for demodulating the sensing signal in digital form to obtain demodulation information; wherein the waveform of each sampling period corresponds to a demodulation value in the demodulation information; a calculation subunit for calculating the touch position information based on the demodulation information and the encoding information corresponding to the encoding method; and a storage subunit for storing the encoding information corresponding to the encoding method.

15. The touch chip according to claim 9, characterized in that, The number of drive channels to which the drive signal is applied by the drive unit is the same as the number of time periods during which the drive signal applied by the drive unit lasts.

16. An electronic device, characterized in that, include: The touchscreen and the touch chip according to any one of claims 9 to 15.

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