Touch control method, sensing signal processing circuit and mutual capacitance touch control device

Abstract

A touch method, a sensing signal processing circuit, and a mutual capacitance touch device, the sensing signal processing circuit comprising: a first signal processing branch, a second signal processing branch, a first mixer of the first signal processing branch, two input ends respectively inputting a superimposed sensing signal and a first local oscillator signal, and a second mixer of the second signal processing branch, the output end is coupled with the input end of the first integrating circuit; the first integrating circuit outputs a baseband signal corresponding to the first sensing signal; a second mixer of a second signal processing branch, two input ends of which are respectively used for inputting the superposed sensing signal and a second local oscillator signal, and an output end of which is coupled with an input end of a second integrating circuit; the second integrating circuit outputs a baseband signal corresponding to the second sensing signal, and the second driving frequency is determined by the first zero frequency of the low-pass filter and the first driving frequency. By adopting the scheme, the complexity of the dual-frequency mutual capacitance touch device cannot be increased too much while the mutual interference between the two driving frequencies can be effectively suppressed.

Description

Technical Field

[0001] The present invention relates to the field of touch technology, and in particular to a touch control method, a sensing signal processing circuit, and a mutual capacitance touch control device. Background Art

[0002] In traditional single-frequency mutual capacitance touch devices, a single driving frequency is usually used to drive the transmitting electrode (TX). The receiving electrode (RX) uses a local oscillator signal of the same frequency to mix with the sensing signal, and the mixed signal is integrated to obtain the signal change of the touch node. The single-frequency mutual capacitance touch device determines whether a touch behavior occurs on the touch node based on the change in the signal change of the touch node.

[0003] Single-frequency mutual capacitance touch devices are difficult to meet the demand for high reporting rates. Currently, there are dual-frequency mutual capacitance touch devices and multi-frequency mutual capacitance touch devices. In traditional dual-frequency mutual capacitance touch devices, two different driving frequencies are used to drive different transmitting electrodes respectively. Compared with single-frequency mutual capacitance touch devices, the reporting rate of dual-frequency mutual capacitance touch devices is doubled.

[0004] In a dual-frequency mutual-capacitive touch device, interference between the two driving frequencies will affect the signal change of the touch node. In the prior art, there are several methods to suppress the mutual interference between the two driving frequencies: 1) using the orthogonality of the two driving frequencies in the measurement time to eliminate mutual interference; 2) using the out-of-band suppression capability of the filter to filter out the interference signal; 3) measuring the interference amount of the interference signal in advance, and filtering out the interference signal through signal processing later.

[0005] The dual-frequency mutual-capacitive touch control device using the above mutual interference suppression method is relatively complex. Summary of the invention

[0006] An object of the present invention is at least to provide a sensing signal processing circuit that can effectively suppress the mutual interference between two driving frequencies without excessively increasing the complexity of a dual-frequency mutual-capacitive touch control device.

[0007] In a first aspect, the present invention provides a sensing signal processing circuit, comprising: a first signal processing branch and a second signal processing branch, the first signal processing branch comprising a first mixer and a first integration circuit, the second signal processing branch comprising a second mixer and a second integration circuit; wherein the first mixer, at its first end, is used to receive a superimposed sensing signal, and at its second end, is used to receive a first local oscillator signal, and its output end is coupled to the input end of the first integration circuit; the superimposed sensing signal comprises a first sensing signal generated by coupling a receiving electrode with a first transmitting electrode, and a second sensing signal generated by coupling the receiving electrode with a second transmitting electrode, the first transmitting electrode receives a driving signal of a first driving frequency, and the second transmitting electrode receives a driving signal of a first driving frequency. The emitter electrode receives a driving signal of a second driving frequency, and the first driving frequency is not equal to the second driving frequency; the first integration circuit outputs a baseband signal corresponding to the first sensing signal; the second mixer, a first end of which is used to receive the superimposed sensing signal, and a second end of which is used to receive a second local oscillator signal, and an output end of which is coupled to an input end of the second integration circuit; the frequency of the first local oscillator signal is equal to the first driving frequency, and the frequency of the second local oscillator signal is equal to the second driving frequency; the second integration circuit outputs a baseband signal corresponding to the second sensing signal; the second integration circuit includes a second low-pass filter, and the second driving frequency is determined by the first zero point frequency of the second low-pass filter.

[0008] The sensing signal processing circuit includes a first signal processing branch and a second signal processing branch. The baseband signal corresponding to the first sensing signal is obtained through the first signal processing branch; the baseband signal corresponding to the second sensing signal is obtained through the second signal processing branch. The first integration circuit and the second integration circuit both include a low-pass filter, and the second driving frequency is determined by the first driving frequency and the first zero frequency of the low-pass filter. In other words, the second driving frequency is associated with the first driving frequency and the first zero frequency. Therefore, by reasonably setting the second driving frequency, the mutual interference between the second driving frequency and the first driving frequency can be reduced, and only the second signal processing branch needs to be added accordingly, which has little effect on the complexity of the dual-frequency mutual capacitance touch device.

[0009] Optionally, the second driving frequency is the sum of the first driving frequency and the first zero frequency.

[0010] The second driving frequency is the sum of the first driving frequency and the first zero point frequency. In other words, the difference between the second driving frequency and the first driving frequency is the first zero point frequency. Therefore, the mutual interference between the second driving frequency and the first driving frequency is zero.

[0011] Optionally, the filter coefficient of the low-pass filter is a first filter coefficient; when the filter coefficient is the first filter coefficient, the offset between the first zero point frequency and the first difference is within a preset threshold range, and the first difference is the difference between the second drive frequency and the first drive frequency.

[0012] Optionally, the sensing signal processing circuit further includes: a control unit, coupled to both low-pass filters, and adapted to adjust the filter coefficients of the two low-pass filters to the first filter coefficients.

[0013] Optionally, the control unit is suitable for: determining candidate filter coefficients of the two low-pass filters based on the scanning time of the drive signal, the candidate filter coefficients corresponding to candidate zero-point frequencies; adjusting the candidate filter coefficients to the first filter coefficients when it is detected that the difference between the second difference and the first drive frequency is outside the threshold range; determining that the candidate filter coefficients are the first filter coefficients when it is detected that the difference between the first difference and the first drive frequency is within the threshold range; the second difference is the difference between the second drive frequency and the candidate zero-point frequency.

[0014] The first driving frequency and the second driving frequency are usually obtained by dividing the reference clock signal generated by the clock signal generating circuit, so there may be a deviation between the difference between the second driving frequency and the first driving frequency and the first zero point frequency. By adjusting the filter coefficient of the low-pass filter, the filter coefficient of the low-pass filter can be adjusted to the first filter coefficient. Thus, it can be ensured that the difference between the second driving frequency and the first driving frequency is at the first zero point frequency.

[0015] Optionally, the first zero frequency is any zero frequency of the low-pass filter.

[0016] Optionally, the first zero-point frequency is the zero-point frequency at which the frequency value of the low-pass filter is minimum.

[0017] Optionally, the low-pass filter has at least two zero frequencies; the first zero frequency is any zero frequency without interference among all the zero frequencies of the low-pass filter.

[0018] Optionally, the first zero-point frequency is a zero-point frequency with no interference and a minimum frequency value among the at least two zero-point frequencies.

[0019] Optionally, the low-pass filter includes any one of the following: a finite impulse response digital filter and an infinite impulse response digital filter.

[0020] In a second aspect, the present invention also provides a touch method, including: determining a first driving frequency; determining a candidate filter coefficient of the low-pass filter based on the acquired scanning time of the driving signal; the candidate filter coefficient corresponds to a candidate zero-point frequency; detecting that the difference between the second difference and the first driving frequency is outside a preset threshold range, adjusting the candidate filter coefficient to the first filter coefficient; and when the filter coefficient of the low-pass filter is the first filter coefficient, the offset between the first zero-point frequency and the first difference is within a preset threshold range, the first difference is the difference between the second driving frequency and the first driving frequency, and the second difference is the difference between the second driving frequency and the candidate zero-point frequency; using the first driving frequency to drive the first transmitting electrode, and using the second driving frequency to drive the second transmitting electrode.

[0021] In a third aspect, the present invention further provides a mutual capacitance touch device, comprising cross-arranged transmitting electrodes and receiving electrodes, wherein a first transmitting electrode among the transmitting electrodes receives a driving signal of a first driving frequency, and a second transmitting electrode among the transmitting electrodes receives a driving signal of a second driving frequency, and the first driving frequency is not equal to the second driving frequency; and a sensing signal processing circuit as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of electrode distribution of a traditional mutual capacitance touch device;

[0023] Figure 2 is a waveform diagram of a driving signal of a transmitting electrode TX1 and a waveform diagram of a driving signal of a transmitting electrode TX2;

[0024] Figure 3 is a waveform diagram of the superimposed sensing signal received by the receiving electrode;

[0025] Figure 4 is a structural schematic diagram of a signal processing device in an embodiment of the present invention;

[0026] Figure 5 It is a pole-zero diagram of a 7th-order FIR digital low-pass filter;

[0027] Figure 6 yes Figure 5 The corresponding amplitude-frequency diagram of the 7th-order FIR digital low-pass filter;

[0028] Figure 7 It is a pole-zero diagram of a 4th-order Bischoff II-type IIR digital low-pass filter;

[0029] Figure 8 yes Figure 7The corresponding amplitude-frequency plot of the 4th-order Bischoff II-type IIR digital low-pass filter;

[0030] Fig. 9 is a flow chart of a touch control method in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] Reference Figure 1 , a schematic diagram of electrode distribution of a mutual capacitance touch device is given. Figure 1 In the figure, the horizontal line represents the transmitting electrode TX (including TX1, TX2, ... TXn), and the vertical line represents the receiving electrode RX (including RX1, RX2, ... RXn). The intersection of the transmitting electrode TX and the receiving electrode RX constitutes a touch node. Whether a touch occurs is determined by detecting the signal change of the touch node, and the coordinates of the corresponding touch node are reported.

[0032] In a dual-frequency mutual-capacitive touch device, two different driving frequencies are used to send driving signals to different transmitting electrodes (such as TX1 and TX2, or TX1 and TX3, etc.). Different driving frequencies are used to distinguish the signal changes of different touch nodes on the same receiving electrode. As a result, the receiving electrode can receive the superposition of the sensing signals of the two driving frequencies.

[0033] like Figure 2 As shown, a waveform diagram of a driving signal on the transmitting electrode TX1 and a waveform diagram of a driving signal on the transmitting electrode TX2 are given. The driving frequency of the driving signal on the transmitting electrode TX1 is different from the driving frequency of the driving signal on the transmitting electrode TX2.

[0034] like Figure 3 As shown, a waveform diagram of the superimposed sensing signal received by the receiving electrode (RX) is given.

[0035] However, in a dual-frequency mutual-capacitive touch device, there is mutual interference between two different driving frequencies, which in turn affects the signal variation of the touch node.

[0036] In the prior art, there are several methods for suppressing the mutual interference between two driving frequencies: 1) using the orthogonality of the two driving frequencies in the measurement time to eliminate the mutual interference; 2) using the out-of-band suppression capability of the filter to filter out the interference signal; 3) measuring the interference amount of the interference signal in advance and filtering out the interference signal through signal processing at a later stage.

[0037] For the above method 1), the two driving frequencies need to be highly accurate. Once one of the driving frequencies is offset, the orthogonality of the two driving frequencies will be destroyed. Therefore, a phase locked loop (PLL) or a direct digital frequency synthesizer (DDS) needs to be set in the dual-frequency mutual capacitance touch device to ensure the accuracy of the two driving frequencies.

[0038] For the above method 2), it is necessary to increase the frequency interval between the two driving frequencies, which makes it difficult to select a suitable driving frequency.

[0039] For the above method 3), it is necessary to know in advance the interference amounts of the interference signals corresponding to different driving frequencies and different measurement durations, which increases the complexity of the dual-frequency mutual capacitance touch control device.

[0040] In an embodiment of the present invention, the sensing signal processing circuit includes a first signal processing branch and a second signal processing branch, the first signal processing branch includes a first mixer and a first integration circuit, and the second signal processing branch includes a second mixer and a second integration circuit. The first integration circuit and the second integration circuit each include a low-pass filter, and the second driving frequency is determined by the first driving frequency and the first zero frequency of the low-pass filter.

[0041] That is to say, the second driving frequency is associated with the first driving frequency and the first zero frequency. Therefore, by reasonably setting the second driving frequency, the mutual interference between the second driving frequency and the first driving frequency can be reduced, and only the corresponding second signal processing branch needs to be added, which has little impact on the complexity of the dual-frequency mutual capacitance touch device.

[0042] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] An embodiment of the present invention provides a sensing signal processing circuit, which can be applied in a dual-frequency mutual capacitance touch control device. The sensing signal processing circuit can be coupled to a receiving electrode, and the receiving electrode can receive a superimposed sensing signal.

[0044] In a specific implementation, the superimposed sensing signal is a superposition of a first sensing signal and a second sensing signal. The first sensing signal is generated by coupling the receiving electrode with the first transmitting electrode, and the first transmitting electrode receives a driving signal of a first driving frequency; the second sensing signal is generated by coupling the receiving electrode with the second transmitting electrode, and the second transmitting electrode receives a driving signal of a second driving frequency; the first driving frequency is not equal to the second driving frequency.

[0045] In the embodiment of the present invention, the first transmitting electrode and the second transmitting electrode mentioned above may refer to two transmitting electrodes scanned in one scanning time. In other words, in different scanning times, there are corresponding first transmitting electrodes and second transmitting electrodes. The first transmitting electrode and the second transmitting electrode constitute all the transmitting electrodes.

[0046] Combination Figure 1 For example, in the first scanning time, the first transmitting electrode is the transmitting electrode TX1, and the second transmitting electrode is the transmitting electrode TX2; in the second scanning time, the first transmitting electrode is the transmitting electrode TX3, and the second transmitting electrode is the transmitting electrode TX4.

[0047] Reference Figure 4 , a structural schematic diagram of a sensing signal processing circuit in an embodiment of the present invention is given.

[0048] In an embodiment of the present invention, the sensing signal processing circuit may include: a first signal processing branch and a second signal processing branch, the first signal processing branch may include a first mixer 41 and a first integration circuit 42, and the second signal processing branch may include a second mixer 43 and a second integration circuit 44, wherein:

[0049] A first input terminal of the first mixer 41 receives the superimposed sensing signal, a second input terminal of the first mixer 41 receives the first local oscillation signal, and an output terminal of the first mixer 41 is coupled to an input terminal of the first integration circuit 42;

[0050] The first integration circuit 42 outputs a baseband signal corresponding to the first sensing signal;

[0051] A first input terminal of the second mixer 43 receives the superimposed sensing signal, a second input terminal of the second mixer 43 receives the second local oscillation signal, and an output terminal of the second mixer 43 is coupled to an input terminal of the second integration circuit 44;

[0052] The second integration circuit 44 outputs a baseband signal corresponding to the second sensing signal.

[0053] In a specific implementation, the frequency of the first local oscillation signal may be equal to the first driving frequency, and the frequency of the second local oscillation signal may be equal to the second driving frequency.

[0054] The sensing signal processing circuit may further include a first local oscillator circuit 45 and a second local oscillator circuit 46 , wherein the first local oscillator circuit 45 is used to generate a first local oscillator signal, and the second local oscillator circuit 46 is used to generate a second local oscillator signal.

[0055] Specifically, the specific circuit structure of the first local oscillator circuit 45 and the principle of generating the first local oscillator signal, and the specific circuit structure of the second local oscillator circuit 46 and the principle of generating the second local oscillator signal can all refer to the implementation of the local oscillator circuit in the prior art, and will not be repeated here.

[0056] In the embodiment of the present invention, the first integration circuit 42 and the second integration circuit 44 may each include a low-pass filter, and the low-pass filter in the first integration circuit 42 and the low-pass filter in the second integration circuit 44 have the same zero frequency. The low-pass filter may include at least one zero frequency, and one of the at least one zero frequency may be selected as the first zero frequency. The second driving frequency is determined by the first driving frequency and the first zero frequency.

[0057] In a specific implementation, the difference between the second driving frequency and the first driving frequency may be equal to the first zero-point frequency. In other words, the second driving frequency is the sum of the first zero-point frequency and the first driving frequency.

[0058] In a specific implementation, the low-pass filter may be an analog filter or a digital filter.

[0059] In some embodiments, the low-pass filter is a digital filter, and specifically may be an infinite impulse response (IIR) digital filter or a finite impulse response (FIR) digital filter.

[0060] In the embodiment of the present invention, for the sake of distinction, the low-pass filter included in the first integration circuit 42 may be referred to as the first low-pass filter, and the low-pass filter included in the second integration circuit 44 may be referred to as the second low-pass filter. The first low-pass filter and the second low-pass filter may be low-pass filters of the same structure, and the filter parameters of the two are the same, so as to ensure that the zero-point frequencies of the two are the same.

[0061] For example, the first low-pass filter and the second low-pass filter are both FIR digital filters. For another example, the first low-pass filter and the second low-pass filter are both IIR digital filters.

[0062] In the first signal processing branch, the first mixed signal output by the first mixer 41 can be low-pass filtered through the first low-pass filter to obtain a baseband signal corresponding to the first sensing signal. Correspondingly, in the second signal processing branch, the second mixed signal output by the second mixer 43 can be low-pass filtered through the second low-pass filter to obtain a baseband signal corresponding to the second sensing signal.

[0063] In the embodiment of the present invention, the first signal processing branch has the same structure as the second signal processing branch. The working principle and processing process of the first signal processing branch and the second signal processing branch are also almost the same. In the following embodiment, the sensing signal processing circuit is described with the first signal processing branch as an example.

[0064] The first low-pass filter may include one or more zero-point frequencies. When the first low-pass filter includes only one zero-point frequency, the zero-point frequency may be used as the first zero-point frequency. When the first low-pass filter includes two or more zero-point frequencies, one may be selected from all zero-point frequencies corresponding to the first low-pass filter as the first zero-point frequency.

[0065] In a specific implementation, the order of the first low-pass filter may be greater than 3, so as to provide at least one zero frequency.

[0066] Take the low-pass filter as a 7th-order FIR digital low-pass filter as an example.

[0067] Reference Figure 5 , a zero-pole diagram of a 7th-order FIR digital low-pass filter is given. Figure 5 In the equation, the horizontal axis is the real axis (Re[z]) and the vertical axis is the imaginary axis (Im[z]). Figure 6 ,yes Figure 5 The corresponding amplitude-frequency diagram of the 7th-order FIR digital low-pass filter. Figure 6 In the figure, the horizontal axis is frequency (Freq) and the vertical axis is amplitude (Amp).

[0068] from Figure 5 It can be seen that the 7th-order FIR digital low-pass filter includes 7 zero frequencies, which are symmetrically distributed on both sides of the real axis. Zero frequency 1 and zero frequency 7 are symmetrical about the real axis, zero frequency 2 and zero frequency 6 are symmetrical about the real axis, zero frequency 3 and zero frequency 5 are symmetrical about the real axis, and zero frequency 4 is the point of the real axis on the unit circle, with a value of Fs / 2, where Fs is the sampling frequency.

[0069] like Figure 6 As shown, F1 is the zero point frequency 1, F2 is the zero point frequency 2, and F3 is the zero point frequency 3.

[0070] Take the low-pass filter as a 4th-order Bischoff II-type IIR digital low-pass filter as an example.

[0071] Reference Figure 7 , a pole-zero diagram of a 4th-order Bischoff II-type IIR digital low-pass filter is given. Figure 7 In the equation, the horizontal axis is the real axis (Re[z]) and the vertical axis is the imaginary axis (Im[z]). Figure 8 ,yes Figure 7The corresponding magnitude-frequency plot of a 4th-order Bischoff type II IIR digital low-pass filter. Figure 8 In the figure, the horizontal axis is frequency (Freq) and the vertical axis is amplitude (Amp).

[0072] from Figure 7 It can be seen that the 4th-order Bischoff II type IIR digital low-pass filter includes 4 zero frequencies, which are symmetrically distributed on both sides of the real axis. Zero frequency 1 and zero frequency 4 are symmetrical about the real axis, and zero frequency 2 and zero frequency 3 are symmetrical about the real axis.

[0073] like Figure 8 As shown, F1 is the zero point frequency 1, and F2 is the zero point frequency 2.

[0074] In a specific implementation, the first zero frequency may be any zero frequency of the first low-pass filter.

[0075] For example, if the first low-pass filter is a 7th-order FIR digital low-pass filter, the first zero-point frequency is F1, or F2, or F3.

[0076] For another example, if the first low-pass filter is a 4th-order Bischoff II-type IIR digital low-pass filter, the first zero-point frequency is F1, or F2.

[0077] In a specific implementation, the first zero-point frequency may be a zero-point frequency with a minimum frequency value of the first low-pass filter.

[0078] For example, if the first low-pass filter is a 7th-order FIR digital low-pass filter, the first zero-point frequency is F1.

[0079] For another example, the first low-pass filter is a 4th-order Bischoff II-type IIR digital low-pass filter, and the first zero frequency is F1.

[0080] In a specific implementation, the first low-pass filter may include two or more zero-point frequencies. In some embodiments, the first zero-point frequency may be a zero-point frequency without interference among all zero-point frequencies of the first low-pass filter.

[0081] For example, the first low-pass filter is a 7th-order FIR digital low-pass filter, and if there is interference on F1, F2 or F3 is selected as the first zero frequency.

[0082] Further, if the first low-pass filter may include two or more zero-point frequencies, the first zero-point frequency may be: a zero-point frequency having no interference and the smallest frequency value among all the zero-point frequencies.

[0083] Continuing with the example that the first low-pass filter is a 7th-order FIR digital low-pass filter, if there is interference on F1 and no interference on F2 and F3, F2 is selected as the first zero frequency.

[0084] In an embodiment of the present invention, the first driving frequency can be selected to drive the first transmitting electrode based on the noise distribution and the interference frequency distribution in the actual application scenario. The first driving frequency can be selected as a frequency with less noise and a larger frequency interval with the interference frequency as much as possible. In other words, a frequency with less interference is selected as the first driving frequency as much as possible.

[0085] After the first driving frequency is selected, the filter coefficient of the first low-pass filter can be determined based on the scanning time required for a complete scan of all transmitting electrodes, and then the first zero point frequency is determined based on the filter coefficient. After the first zero point frequency is determined, the first zero point frequency is summed with the first driving frequency, and the sum obtained is the second driving frequency.

[0086] In a specific implementation, different mutual capacitance touch devices allocate different scanning times to the transmitting electrode for one scan, and the corresponding filter coefficients of the first low-pass filter are different. The corresponding filter coefficients can be determined in advance based on different scanning times.

[0087] In a specific implementation, the dual-frequency mutual-capacitive touch device may include a clock signal generating circuit and a frequency divider. The clock signal generating circuit generates and outputs a reference clock signal, and the reference clock signal is input to the frequency divider. After the reference clock signal is divided by the frequency divider, a first driving frequency and a second driving frequency may be obtained.

[0088] However, there is a scenario where the difference between the second driving frequency and the first driving frequency may not be exactly equal to the first zero point frequency. That is, there is a certain deviation value △1 between the difference between the second driving frequency and the first driving frequency (hereinafter referred to as the second difference) and the first zero point frequency, and △1 is not equal to 0.

[0089] In some embodiments, if the deviation value △1 is outside the preset threshold range, the filter coefficient of the first low-pass filter is adjusted. By adjusting the filter coefficient of the first low-pass filter, the first zero point frequency is also adjusted accordingly. When the filter coefficient of the first low-pass filter is adjusted to the first filter coefficient, the deviation value between the second difference and the adjusted first zero point frequency is updated to △2, and △2 is within the preset threshold range.

[0090] In other embodiments, if the deviation value △1 is not equal to 0, the filter coefficient of the first low-pass filter is adjusted. By adjusting the filter coefficient of the first low-pass filter, the first zero point frequency is also adjusted accordingly. When the filter coefficient of the first low-pass filter is adjusted to the first filter coefficient, the deviation value between the second difference and the adjusted first zero point frequency is 0.

[0091] In an embodiment of the present invention, for a dual-frequency mutual-capacitive touch control device, a first driving frequency, a second driving frequency, and an adjusted first zero-point frequency can be predetermined, and the first driving frequency, the second driving frequency, and the adjusted first zero-point frequency can be stored in a memory by burning. When the dual-frequency mutual-capacitive touch control device is working, the first driving frequency, the second driving frequency, and the adjusted first zero-point frequency can be read from the memory, the first transmitting electrode can be driven by the first driving frequency, the second transmitting electrode can be driven by the second driving frequency, and the filter coefficient of the first low-pass filter can be set to the first filter coefficient.

[0092] That is to say, the first driving frequency, the second driving frequency and the adjusted first zero-point frequency can be stored in the memory in advance, and can be directly called from the memory when the dual-frequency mutual-capacitive touch control device is working.

[0093] Alternatively, the corresponding first driving frequency and the second driving frequency may be selected based on a specific working scenario of the dual-frequency mutual-capacitive touch control device, and the corresponding first zero-point frequency may be determined.

[0094] Specifically, in an embodiment of the present invention, the sensing signal processing circuit may further include a control unit, which may be coupled to the first low-pass filter. The control unit is adapted to adjust the filter coefficient of the first low-pass filter to the first filter coefficient.

[0095] The control unit can determine candidate filter coefficients of the first low-pass filter based on the scanning time of the driving signal, and the candidate filter coefficients correspond to candidate zero-point frequencies. The scanning time of the driving signal is the time for all the first transmitting electrodes and the second transmitting electrodes to be completely scanned once.

[0096] The control unit can detect whether the difference between the first difference and the first driving frequency is within a preset threshold range. If it is detected that the difference between the first difference and the first driving frequency is within the preset threshold range, the candidate zero point frequency can be used as the first zero point frequency; conversely, if it is detected that the difference between the first difference and the first driving frequency is outside the preset threshold range, the candidate filter coefficient can be adjusted to adjust the candidate filter coefficient to the first filter coefficient, so that the difference between the first difference and the first driving frequency is within the preset threshold range. The above-mentioned first difference is the difference between the second driving frequency and the candidate zero point frequency.

[0097] Therefore, by adjusting the filter coefficient of the first low-pass filter, it can be ensured that the difference between the second driving frequency and the first driving frequency is the zero frequency of the first low-pass filter, thereby avoiding mutual interference between the second driving frequency and the first driving frequency.

[0098] It can be understood that the process of adjusting the filter coefficients of the second low-pass filter can correspond to the process of adjusting the filter coefficients of the first low-pass filter, and the filter coefficients of the second low-pass filter are also adjusted to the first filter coefficients.

[0099] The working principle and working process of the sensing signal processing circuit provided in the embodiment of the present invention are described below.

[0100] For the first signal processing branch:

[0101] The first signal processing branch receives the superimposed sensing signal, which includes the first sensing signal and the second sensing signal. The superimposed sensing signal is input to the first input terminal of the first mixer 41 .

[0102] The first sensing signal is input to the first mixer 41, and the output of the first mixer 41 is: a baseband signal of 0 frequency (that is, the baseband signal corresponding to the touch node generated by the transmitting electrode Tx1 and the current receiving electrode), and a high-frequency signal of 2 times the frequency (the frequency is 2 times the first driving frequency). The baseband signal is a useful signal, and the high-frequency signal of 2 times the frequency is a useless signal. The high-frequency signal of 2 times the frequency can be filtered out by the first integration circuit 42.

[0103] The second sensing signal is input to the first mixer 41, and the output of the first mixer 41 is: a difference frequency signal (frequency is the difference between the second driving frequency and the first driving frequency), and a sum frequency signal (frequency is the sum of the second driving frequency and the first driving frequency). For the first signal processing branch, the sum frequency signal and the difference frequency signal are both useless signals, and the sum frequency signal can be filtered out by the first integration circuit 42. The difference frequency signal is a low-frequency signal, which is difficult to be filtered out by the first integration circuit 42, and then interferes with the baseband signal of 0 frequency.

[0104] In the embodiment of the present invention, the second driving frequency is the sum of the first driving frequency and the first zero frequency of the low-pass filter. Therefore, the difference between the first driving frequency and the second driving frequency is exactly the zero point position of the filter. Therefore, the above-mentioned difference frequency signal (the frequency is the difference between the second driving frequency and the first driving frequency) will not interfere with the baseband signal of 0 frequency.

[0105] The superimposed sensing signal is processed by the first signal processing branch to finally obtain a baseband signal corresponding to the touch node generated by the transmitting electrode Tx1 and the current receiving electrode.

[0106] The working principle and working process of the second signal processing branch may refer to the first signal processing branch.

[0107] Reference Fig. 9, an embodiment of the present invention further provides a touch method, which is described in detail through specific steps below.

[0108] Step 901, determining a first driving frequency.

[0109] In a specific implementation, the first driving frequency can be selected to drive the first transmitting electrode based on the noise distribution and the interference frequency distribution in the actual application scenario. The first driving frequency can be selected as a frequency with less noise and a larger frequency interval with the interference frequency as much as possible. In other words, a frequency with less interference is selected as the first driving frequency as much as possible.

[0110] Step 902: Determine candidate filter coefficients of a low-pass filter based on the acquired scanning time of the driving signal.

[0111] In the embodiment of the present invention, after the first driving frequency is selected, candidate filter coefficients of the low-pass filter may be determined based on the scanning time required for a complete scanning of all transmitting electrodes (ie, the receiving time of the driving signal).

[0112] In a specific implementation, different touch control devices allocate different scanning times to the transmitting electrodes for a complete scan, and the corresponding low-pass filter coefficients are different. The corresponding candidate filter coefficients can be determined in advance based on different scanning times.

[0113] In a specific implementation, the dual-frequency mutual-capacitive touch device may include a clock signal generating circuit and a frequency divider. The clock signal generating circuit generates and outputs a reference clock signal, and the reference clock signal is input to the frequency divider. After the reference clock signal is divided by the frequency divider, a first driving frequency and a second driving frequency may be obtained.

[0114] There is a scenario where the second difference between the obtained second driving frequency and the first driving frequency and the first zero frequency corresponding to the candidate filter coefficient are within a preset threshold range. In this scenario, step 904 can be directly executed without executing step 903.

[0115] That is to say, if it is determined that the second difference and the first zero point frequency corresponding to the candidate filter coefficient are within the preset threshold range, step 904 is executed; if it is determined that the second difference and the first zero point frequency corresponding to the candidate filter coefficient are outside the preset threshold range, steps 903 to 904 are executed.

[0116] Step 903: If it is detected that the difference between the second difference and the first driving frequency is outside the preset threshold range, the candidate filter coefficient is adjusted to the first filter coefficient. However, there is also a scenario where the difference between the second driving frequency and the first driving frequency may not be exactly equal to the first zero point frequency. In other words, there is a certain deviation value △1 between the difference between the second driving frequency and the first driving frequency (hereinafter referred to as the second difference) and the first zero point frequency, and △1 is not equal to 0.

[0117] In some embodiments, if the deviation value △1 is outside the preset threshold range, the filter coefficient of the first low-pass filter is adjusted. By adjusting the filter coefficient of the first low-pass filter, the first zero point frequency is also adjusted accordingly. When the filter coefficient of the first low-pass filter is adjusted to the first filter coefficient, the deviation value between the second difference and the adjusted first zero point frequency is updated to △2, and △2 is within the preset threshold range.

[0118] In other embodiments, if the deviation value △1 is not equal to 0, the filter coefficient of the first low-pass filter is adjusted. By adjusting the filter coefficient of the first low-pass filter, the first zero point frequency is also adjusted accordingly. When the filter coefficient of the first low-pass filter is adjusted to the first filter coefficient, the deviation value between the second difference and the adjusted first zero point frequency is 0.

[0119] Step 904: drive the first transmitting electrode with a first driving frequency, and drive the second transmitting electrode with a second driving frequency.

[0120] In the embodiment of the present invention, after the first driving frequency and the second driving frequency are determined, the first driving frequency may be used to drive the first transmitting electrode; and the second driving frequency may be used to drive the second transmitting electrode.

[0121] In a specific implementation, the execution process of the above steps 901 to 904 may refer to the relevant description of the sensing signal processing circuit in the above embodiment.

[0122] The control unit may be a chip or circuit structure with data processing capability, such as a controller, a microcontroller, or a central processing unit.

[0123] The present invention further provides a mutual capacitance touch control device, comprising the sensing signal processing circuit provided by any one of the above embodiments.

[0124] In a specific implementation, the mutual capacitance touch control device mentioned above may be a dual-frequency mutual capacitance touch control device.

[0125] A person skilled in the art may understand that all or part of the steps in the various methods of the above embodiments may be completed by instructing the relevant hardware through a program, and the program may be stored in a computer-readable storage medium, which may include: ROM, RAM, disk or CD, etc.

[0126] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A sensing signal processing circuit, characterized in that: include: A first signal processing branch and a second signal processing branch, wherein the first signal processing branch includes a first mixer and a first integration circuit, and the second signal processing branch includes a second mixer and a second integration circuit; wherein, The first mixer has a first input terminal for receiving a superimposed sensing signal, a second input terminal for receiving a first local oscillator signal, and an output terminal coupled to an input terminal of the first integrating circuit; the superimposed sensing signal includes a first sensing signal generated by coupling a receiving electrode with a first transmitting electrode, and a second sensing signal generated by coupling a receiving electrode with a second transmitting electrode, the first transmitting electrode receives a driving signal of a first driving frequency, the second transmitting electrode receives a driving signal of a second driving frequency, and the first driving frequency is not equal to the second driving frequency; The first integration circuit outputs a baseband signal corresponding to the first sensing signal; The second mixer has a first input terminal for receiving the superimposed sensing signal, a second input terminal for receiving a second local oscillator signal, and an output terminal coupled to an input terminal of the second integrating circuit; the frequency of the first local oscillator signal is equal to the first driving frequency, and the frequency of the second local oscillator signal is equal to the second driving frequency; The second integration circuit outputs a baseband signal corresponding to the second sensing signal; the first integration circuit and the second integration circuit each include a low-pass filter, and the second driving frequency is determined by the first driving frequency and the first zero frequency of the low-pass filter.

2. The sensing signal processing circuit according to claim 1, characterized in that: The second driving frequency is the sum of the first driving frequency and the first zero frequency.

3. The sensing signal processing circuit according to claim 2, characterized in that: The filter coefficient of the low-pass filter is the first filter coefficient; when the filter coefficient is the first filter coefficient, the offset between the first zero point frequency and the first difference is within a preset threshold range, and the first difference is the difference between the second drive frequency and the first drive frequency.

4. The sensing signal processing circuit according to claim 3, characterized in that: Also includes: The control unit is coupled to both low-pass filters and is adapted to adjust the filter coefficients of the two low-pass filters to the first filter coefficients.

5. The sensing signal processing circuit according to claim 4, characterized in that: The control unit is adapted to: determine candidate filter coefficients of the two low-pass filters based on the scanning time of the driving signal, the candidate filter coefficients corresponding to candidate zero-point frequencies; and adjust the candidate filter coefficients to the first filter coefficients when it is detected that the difference between the second difference and the first driving frequency is outside the threshold range; detecting that a difference between the first difference and the first driving frequency is within the threshold range, and determining that the candidate filter coefficient is the first filter coefficient; The second difference is a difference between the second driving frequency and the candidate zero-point frequency.

6. The sensing signal processing circuit according to claim 1, characterized in that: The first zero frequency is any zero frequency of the low-pass filter.

7. The sensing signal processing circuit according to claim 1, characterized in that: The first zero-point frequency is the zero-point frequency at which the frequency value of the low-pass filter is the minimum.

8. The sensing signal processing circuit according to claim 1, wherein: The low-pass filter has at least two zero-point frequencies; the first zero-point frequency is any zero-point frequency without interference among all the zero-point frequencies of the low-pass filter.

9. A touch control method, characterized in that: Applicable to the sensing signal processing circuit according to claims 1 to 8, the touch control method comprises: determining the first driving frequency; Determining candidate filter coefficients of the low-pass filter based on the acquired scanning time of the driving signal; the candidate filter coefficients correspond to candidate zero-point frequencies; When it is detected that the difference between the second difference and the first driving frequency is outside a preset threshold range, the candidate filter coefficient is adjusted to the first filter coefficient; and when the filter coefficient of the low-pass filter is the first filter coefficient, the offset between the first zero point frequency and the first difference is within a preset threshold range, the first difference is the difference between the second driving frequency and the first driving frequency, and the second difference is the difference between the second driving frequency and the candidate zero point frequency; The first transmitting electrode is driven with the first driving frequency, and the second transmitting electrode is driven with the second driving frequency.

10. A mutual capacitance touch device, characterized in that: It comprises a transmitting electrode and a receiving electrode arranged crosswise, wherein a first transmitting electrode among the transmitting electrodes receives a driving signal of a first driving frequency, and a second transmitting electrode among the transmitting electrodes receives a driving signal of a second driving frequency, and the first driving frequency is not equal to the second driving frequency; And, the sensing signal processing circuit as described in any one of claims 1 to 8.

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