CN106775046B - Same-frequency noise processing method, same-frequency noise processing device and same-frequency noise processing system - Google Patents
Same-frequency noise processing method, same-frequency noise processing device and same-frequency noise processing system Download PDFInfo
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- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
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- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
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Abstract
The invention relates to a same-frequency noise processing method, a same-frequency noise processing device and a same-frequency noise processing system. The method comprises the following steps: step a: loading a driving signal on the first electrode, wherein the driving signal is coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode to generate an induction signal; step b: demodulating the induction signal on the second electrode, calculating a system phase value of the noise source system according to the demodulated value of the induction signal, judging whether the same-frequency noise exists in the current induction signal or not according to the calculated system phase value of the noise source system, and executing the step c if the same-frequency noise exists; step c: and calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, and acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value to eliminate the same-frequency noise in the driving signal frequency. The invention can greatly improve the user experience.
Description
Technical Field
The invention relates to the technical field of same-frequency noise processing, in particular to a same-frequency noise processing method, a same-frequency noise processing device and a same-frequency noise processing system.
Background
The position detection system is a key technology in the field of human-computer interaction, greatly improves human-computer interaction experience, and is widely applied to the fields of smart phones, notebook computers, personal consumer electronics, ATMs, ordering platforms and the like. When a user moves a finger or an electronic pen head or other conductors on a touch pad or other interactive interfaces to perform clicking or line drawing operations, the position detection system is required to be capable of accurately responding to the input will of the user.
In general, a position detection system detects a touch position of a user through a micro-capacitance detection technology. The method is characterized in that a micro-electrical signal (namely a driving signal) is loaded in a touch sensing area, a signal loop is formed through capacitive coupling, and a signal (namely a sensing signal) is detected at the rear end of the loop. When a conductor approaches the induction area, the capacitive electric effect is generated, which is equivalent to changing the impedance value of a signal loop, so that the detection value of the induction signal is influenced, and finally, the actual touch position is judged according to the variation of the detection value.
Although the position detection system is mature, the application environment is more and more complex and varied, and design engineers are faced with many challenges, wherein the improvement of the anti-interference performance is the most urgent one and is a difficult point in the whole micro-capacitance detection industry. The interference of the position detection system mainly comes from wireless communication equipment, LCD and charger, the main frequency components of the interference are randomly distributed in the interval of 1 KHZ-10 MHZ, and the driving signal frequency of the position detection system is usually in the interval of 50 KHZ-500 KHZ. A reasonable low-pass or high-pass filter designed on the inductive signal loop helps to suppress part of the noise. For the same frequency noise of the driving signal frequency of the proximity position detection system or other noise source systems (in a mobile communication system, in order to improve the frequency utilization rate and increase the system capacity, a frequency reuse technology is often adopted, and frequency reuse means that after a certain distance, in a given coverage area, a plurality of cells using the same group of frequencies exist, the cells are called as the same frequency cells, the interference between the same frequency cells is called as the same frequency interference, and the same frequency interference is the same frequency noise), the filter is obviously not an effective method. The co-frequency noise mixed in the position detection system or other noise source system is terrible, and once mixed with the induction signal, the co-frequency noise and the induction signal are difficult to separate again. This has the most direct consequence of causing variations in the sensed signal values in the back-end circuitry, which are equivalent to the effects of user touch-induced variations on the data side, and in severe cases even affect the normal use of the position detection system or other noise source systems.
In order to solve the above problems, the technical solution adopted in the prior art for processing the same-frequency noise is as follows:
firstly, noise frequency demodulation: on the premise of not generating a driving signal, theoretically, only a noise signal exists in the position detection system, a noise frequency component is demodulated, and a frequency point with the minimum frequency component is selected as the frequency of the next driving-sensing signal. The method can effectively avoid the noise with slow frequency component change, but cannot avoid the noise with fast frequency component change. Since the noise detection and the sensing signal detection do not occur at the same time, the non-noise frequency point f obtained by the noise detection demodulation in the time period T1 may have large noise when the sensing signal detection is performed in the time period T2, and therefore, the noise processing real-time performance of the noise frequency demodulation method is not high.
Secondly, synchronizing the clock of the noise source: noise generated by some special noise sources appears intermittently in a time domain, and a clock synchronization relation can be established with the noise sources theoretically, so that induction signal detection is only carried out within the intermittent time of the noise, and the noise can be effectively avoided. But the synchronization relationship is difficult to establish, and the short pause time limits the popularization and application of the method.
Therefore, there is a need to provide a real-time calculation method for quantifying co-channel noise, thereby suppressing the negative effects of co-channel noise in a location detection system or other noise source systems.
Disclosure of Invention
The invention provides a same-frequency noise processing method, a same-frequency noise processing device and a same-frequency noise processing system, aiming at realizing the real-time detection and elimination of the same-frequency noise and inhibiting the negative effect of the same-frequency noise in a position detection system or other noise source systems.
In order to solve the problems proposed above, the technical scheme adopted by the invention is as follows:
a method for processing same-frequency noise comprises the following steps:
step a: loading a driving signal on the first electrode, wherein the driving signal is coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode to generate an induction signal;
step b: demodulating the induction signal on the second electrode, calculating a system phase value of the noise source system according to the demodulated value of the induction signal, judging whether the same-frequency noise exists in the current induction signal or not according to the calculated system phase value of the noise source system, and executing the step c if the same-frequency noise exists;
step c: and calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, and acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value to eliminate the same-frequency noise in the driving signal frequency.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: in the step a, the driving signal applied to the first electrode is:
TX＝sin(ωt)
the generated induction signal is:
Rx＝Asin(ωt+φ)+noise
in the above equation, TX is the driving signal,
for the driving signal frequency f, RX is the induced signal, A is the signal attenuation coefficient, and φ is the signal phase, i.e. the system phase value of the noise source system.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: in step b, the demodulation method for demodulating the sensing signal on the second electrode specifically includes: unfolding the induction signal RX, carrying out orthogonal demodulation on the unfolded induction signal RX to obtain a cosine component and a sine component of the induction signal RX, and calculating the amplitude R of the induction signal RX at the driving frequency f according to the cosine component and the sine component; the induction signal RX expansion formula is:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt)
in the above formula, B and θ are respectively a noise attenuation coefficient and a noise phase;
the specific formula for obtaining the cosine component and the sine component and calculating the amplitude R of the induction signal RX at the driving frequency f according to the cosine component and the sine component is as follows:
I＝Acos(φ)+Bcos(θ)
Q＝Asin(φ)+Bsin(θ)
in the above formula, I is a cosine component and Q is a sine component.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: in the step b, the judging manner of judging whether the same-frequency noise exists in the current sensing signal according to the calculated system phase value of the noise source system is as follows: judging whether the system phase value of the noise source system calculated in the step b is equal to the real system phase value of the noise source system, and if the system phase value of the noise source system calculated in the step b is equal to the real system phase value of the noise source system, judging that the same-frequency noise does not exist in the current induction signal; and c, if the system phase value of the noise source system calculated in the step c is not equal to the real system phase value of the noise source system, judging that the same-frequency noise exists in the current sensing signal.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: in the step c, the calculation method for obtaining the noise-free demodulated value of the modified driving signal frequency and the noise of the frequency near the modified driving signal frequency according to the noise quantized value specifically includes: a driving signal coupled from a first electrode to a second electrode, wherein the sampling time is T, f is the frequency of the driving signal, bi tfreq is 1/T, and bi tfreq is the minimum variation unit of the frequency f of the driving signal; the influence coefficients of the demodulated values of the signal with the driving signal frequency f at five frequency points of f-2 × bi tfreq, f-bi tfreq, f + bi tfreq and f +2 × bi tfreq are [0,0.5,1,0.5,0], and the mutual influence relation between the demodulated value at any frequency point and the demodulated value at the adjacent frequency point is as follows:
in the above formula, [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulated values of five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bi tfreq respectively,
and modifying the processed noiseless demodulated value of the signal with the driving signal frequency f at the corresponding frequency point.
The embodiment of the invention adopts another technical scheme that: a common-frequency noise processing device comprises a CPU controller, a modulator, a first electrode, a second electrode and a demodulator; the CPU controller is used for controlling the modulator to load a driving signal on the first electrode, and the driving signal is coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode to generate an induction signal;
the CPU controller control demodulator demodulates the induction signal on the second electrode;
the CPU controller calculates a system phase value of the noise source system according to the demodulated value of the induction signal, and judges whether the same-frequency noise exists in the current induction signal or not according to the calculated system phase value of the noise source system; if the same-frequency noise exists, calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value, and eliminating the same-frequency noise in the driving signal frequency.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: the demodulation mode of the demodulator for demodulating the induction signal on the second electrode specifically comprises the following steps: unfolding the induction signal RX, carrying out orthogonal demodulation on the unfolded induction signal RX to obtain a cosine component and a sine component of the induction signal RX, and calculating the amplitude R of the induction signal RX at the driving frequency f according to the cosine component and the sine component; the induction signal RX expansion formula is:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt)
in the above-mentioned formula,
for driving signal frequency f, A and phi are respectively a signal attenuation coefficient and a signal phase, and B and theta are respectively a noise attenuation coefficient and a noise phase;
the specific formula for obtaining the cosine component and the sine component and calculating the amplitude R of the induction signal RX at the driving frequency f according to the cosine component and the sine component is as follows:
I＝Acos(φ)+Bcos(θ)
Q＝Asin(φ)+Bsin(θ)
in the above formula, I is a cosine component and Q is a sine component.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: the CPU controller judges whether the same-frequency noise exists in the current induction signal in the following manner: judging whether the calculated system phase value of the noise source system is equal to the real system phase value of the noise source system or not, and if the calculated system phase value of the noise source system is equal to the real system phase value of the noise source system, judging that the same-frequency noise does not exist in the current sensing signal; and if the calculated system phase value of the noise source system is not equal to the real system phase value of the noise source system, judging that the same-frequency noise exists in the current sensing signal.
The technical scheme adopted by the embodiment of the invention also comprises the following steps: the CPU controller calculates a noise quantization value of the driving signal frequency and the noise of the frequency nearby, and the calculation mode of acquiring the corrected noise demodulation value of the driving signal frequency and the noise of the frequency nearby according to the noise quantization value is as follows: a driving signal coupled from a first electrode to a second electrode, wherein the sampling time is T, f is the frequency of the driving signal, bi tfreq is 1/T, and bi tfreq is the minimum variation unit of the frequency f of the driving signal; the influence coefficients of the demodulated values of the signal with the driving signal frequency f at five frequency points of f-2 × bi tfreq, f-bi tfreq, f + bi tfreq and f +2 × bi tfreq are [0,0.5,1,0.5,0], and the mutual influence relation between the demodulated value at any frequency point and the demodulated value at the adjacent frequency point is as follows:
in the above formula, [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulated values of five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bi tfreq respectively,
and modifying the processed noiseless demodulated value of the signal with the driving signal frequency f at the corresponding frequency point.
The embodiment of the invention adopts another technical scheme that: a same frequency noise processing system comprises a noise source system and a same frequency noise processing device, wherein the noise source system and the same frequency noise processing device are in signal connection; and eliminating the same-frequency noise in the noise source system through the same-frequency noise processing device.
Compared with the prior art, the invention has the beneficial effects that: the same-frequency noise processing method, the same-frequency noise processing device and the same-frequency noise processing system of the embodiment of the invention load the driving signal on the first electrode, acquire the demodulation value of the induction signal on the second electrode in a demodulation mode, calculate the system phase according to the demodulation value, and judge whether the current induction signal contains the same-frequency noise according to the calculated value of the system phase, thereby solving the real-time problem of the same-frequency noise processing; and through the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, the corrected drive signal and the noiseless demodulation value of the noise of the adjacent frequency are obtained, finally, the noise elimination processing is realized, the negative effect of the same-frequency noise in the position detection system is effectively inhibited, and the user experience is greatly improved.
Drawings
FIG. 1 is a schematic structural diagram of a co-frequency noise processing method according to an embodiment of the present invention;
FIG. 2 is a graph of a spectrum of a sampled signal;
FIG. 3 is a schematic structural diagram of a co-frequency noise processing system according to an embodiment of the present invention;
FIG. 4 is a circuit diagram of a noise processing system of an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an application system of a co-frequency noise processing system according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
In the following embodiments of the present invention, only the co-channel noise processing of the position detection system is taken as an example for explanation, but the present invention is not limited to this, and the present invention is also applicable to the co-channel noise processing of other noise source systems, such as a cellular system, a trunking system, or a satellite communication system.
Fig. 1 is a flowchart of a co-frequency noise processing method according to an embodiment of the invention. The method for processing the same-frequency noise comprises the following steps:
step S100: the CPU controller controls the modulator to load a driving signal on the first electrode, and the driving signal is coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode to generate an induction signal;
in step S100, the loading a driving signal on the first electrode, the driving signal being coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode, and the generating an induction signal specifically includes: the CPU controller controls the modulator to load a driving signal of TX on the first electrode, and then:
TX＝sin(ωt) (1)
in the formula (1), the first and second groups,
is the drive signal frequency f; the TX signal is coupled to the second electrode through the coupling capacitance between the first electrode and the second electrodeAbove, the process can be equivalent to that the TX signal is communicated to the second electrode through the capacitive impedance, and then the induced signal detected by the second electrode is RX:
Rx＝Asin(ωt+φ)+noise (2)
in formula (2), a and phi are the signal attenuation coefficient and the signal phase, i.e. the system phase of the position detection system, respectively; in general, the system phase phi of the position detection system is fixed and can be regarded as a known quantity, and then
noise＝Bsin(ωt+θ) (3)
In formula (3), B and θ are respectively a noise attenuation coefficient and a noise phase, and the noise is randomly changed, that is, B and θ are represented as random values; in the embodiment of the present invention, the driving signal applied to the first electrode is a sine wave driving signal, but the present invention is not limited thereto, and the application of other types of driving signals is also applicable, such as square wave signals.
Step S200: demodulating the induction signal on the second electrode through a CPU controller control modem to obtain a demodulation value of the induction signal;
in step S200, the sensing signal coupled out from the second electrode may be analog-to-digital converted by the ADC and then transmitted to the demodulator, and demodulated by the CPU controller, where the ADC may be implemented in any module, such as the CPU controller, the modulator, or the demodulator; the method for demodulating the sensing signal on the second electrode by the demodulator specifically includes: and spreading the induction signal RX, wherein the expansion formula of the induction signal RX is as follows:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt) (4)
performing quadrature demodulation on the expanded sensing signal RX to obtain a cosine component (I value) and a sine component (Q value) of the sensing signal RX, and calculating an amplitude R of the sensing signal RX at the driving frequency f according to the cosine component and the sine component, wherein the specific formula is as follows:
I＝Acos(φ)+Bcos(θ) (5)
Q＝Asin(φ)+Bsin(θ) (6)
step S300: calculating a system phase value arctan (Q/I) of the position detection system according to the demodulated value of the induction signal, and judging whether the same-frequency noise exists in the current induction signal according to the calculated system phase value of the position detection system; if the same-frequency noise exists, executing step S400; if no same-frequency noise exists, executing step S500;
in step 300, the system phase values of the position detection system are:
when there is no same-frequency noise, i.e. B is 0, then
The calculated system phase value of the position detection system is equal to the real system phase value of the position detection system;
when there is same frequency noise: i.e., B ≠ 0 and φ ≠ θ,
the method for judging whether the same-frequency noise exists in the induction signal through the calculated system phase value of the position detection system is as follows: judging whether the calculated system phase value of the position detection system is equal to the real system phase value of the position detection system or not, and if the calculated system phase value of the position detection system is equal to the real system phase value of the position detection system, judging that the current induction signal does not have the same-frequency noise; and if the calculated system phase value of the position detection system is not equal to the real system phase value of the position detection system, judging that the same-frequency noise exists in the current induction signal.
Step S400: calculating a noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, acquiring a corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value, and eliminating the same-frequency noise in the driving signal frequency;
in step S400, the noise-free mediation value of the modified driving signal frequency and the frequency noise in the vicinity thereof has eliminated the influence of the same-frequency noise; the calculation method of the noise-free mediation value of the driving signal frequency and the noise of the frequency nearby the driving signal frequency is specifically as follows: the driving signal coupled from the first electrode to the second electrode, and through the hanning window, the sampling time is T, and the spectrum curve of the sampling signal is as shown in fig. 2, which is a spectrum curve graph of the sampling signal (the technology is well known in the industry, and the description of the invention will not be repeated). Wherein f is the driving signal frequency, bi tfreq is 1/T, and bi tfreq is the minimum variation unit of the driving signal frequency f in the position detection system. It is deduced from the above curve theory that the influence coefficients of the demodulated values of the signal at the driving signal frequency f at five frequency points f-2 × bi tfreq, f-bi tfreq, f + bi tfreq, and f +2 × bi tfreq are [0,0.5,1,0.5,0], respectively, and the mutual influence relationship between the demodulated value at any frequency point and the demodulated values at adjacent frequency points is:
in formula (9) and formula (10), [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulated values of the five frequency points f-2 × bitfreq, f-bitfreq, f + bitfreq, and f +2 × bitfreq, respectively, can be directly obtained from step 200. While
The noiseless demodulated value after the correction processing on the corresponding frequency point is the signal of the driving signal frequency f, and is obtained by calculation of formula (9) and formula (10).
Step S500: calculating a user touch position by using the induction signal demodulation value or the corrected noiseless demodulation value;
in step S500, the first electrode and the second electrode are multi-electrode arrays, the plurality of electrode arrays are arranged perpendicularly to each other, dense cross nodes are formed on the entire touch panel, and each cross node is regarded as a coupling capacitor. When a user touches the touch screen, the size of the coupling capacitor near the touch position can be changed, so that the touch position of the user can be calculated only by detecting the variable quantity of each capacitor. Specifically, a driving signal is applied to the first electrode array of the first electrode, and simultaneously the sensing signals of all the electrode arrays of the second electrode are detected and demodulated, and the demodulated value of the sensing signal can be regarded as a cross-coupling capacitance value of the two electrode arrays. And sequentially finishing the loading of the driving signals of all the electrode arrays on the first electrode in the same way, so that all the cross coupling capacitance values of the touch panel plane can be obtained. Setting the capacitance value when the user does not operate as a reference value, and when the user performs touch operation, quickly calculating the accurate touch position of the user by comparing the real-time value of the capacitance value with the reference value; when the method is applied to other fields of noise source systems, other types of signal indexes can be calculated by utilizing the induction signal demodulation value or the corrected noiseless demodulation value.
Referring to fig. 3 and fig. 4 together, fig. 3 is a schematic structural diagram of a co-frequency noise processing apparatus according to an embodiment of the present invention; fig. 4 is a circuit diagram of a noise processing apparatus according to an embodiment of the present invention. The same-frequency noise processing device comprises a CPU controller, a modulator, a first electrode, a second electrode and a demodulator; the CPU controller is respectively connected with a modulator and a demodulator, the modulator is connected with the first electrode, and the demodulator is connected with the second electrode;
the CPU controller is used for controlling the modulator to load a driving signal on the first electrode, and the driving signal is coupled to the second electrode through the coupling capacitor between the first electrode and the second electrode to generate an induction signal; wherein, the step of controlling the modulator to load the driving signal on the first electrode by the CPU controller specifically comprises: the driving signal loaded on the first electrode is TX, then:
TX＝sin(ωt) (1)
in the formula (1), the first and second groups,
is the drive signal frequency f; the driving signal TX is coupled to the second electrode through the coupling capacitor between the first electrode and the second electrode, which may be equivalent to that the driving signal TX is communicated to the second electrode through a capacitive impedance, and then the sensing signal detected by the second electrode is RX:
Rx＝Asin(ωt+φ)+noise (2)
in formula (2), a and phi are the signal attenuation coefficient and the signal phase, i.e. the system phase of the position detection system, respectively; in general, the system phase phi of the position detection system is fixed and can be regarded as a known quantity, and then
noise＝Bsin(ωt+θ) (3)
In the formula (3), B and θ are respectively a noise attenuation coefficient and a noise phase, and the noise changes randomly, that is, B and θ represent random values.
The CPU controller is used for controlling the demodulator to demodulate the induction signal on the second electrode to obtain a demodulation value of the induction signal; the method for demodulating the sensing signal on the second electrode by the demodulator specifically includes: and spreading the induction signal RX, wherein the expansion formula of the induction signal RX is as follows:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt) (4)
performing quadrature demodulation on the expanded sensing signal RX to obtain a cosine component (I value) and a sine component (Q value) of the sensing signal RX, and calculating an amplitude R of the sensing signal RX at the driving frequency f according to the cosine component and the sine component, wherein the specific formula is as follows:
I＝Acos(φ)+Bcos(θ) (5)
Q＝Asin(φ)+Bsin(θ) (6)
the CPU controller also comprises a noise judgment module, a noise elimination module and a position calculation module, wherein the noise judgment module, the noise elimination module and the position calculation module are sequentially connected;
the noise judgment module is used for calculating a system phase value arctan (Q/I) of the position detection system according to the demodulated value of the sensing signal and judging whether the same-frequency noise exists in the current sensing signal according to the calculated system phase value of the position detection system; if the same-frequency noise exists, acquiring a corrected noiseless demodulation value through a noise elimination module; if the same-frequency noise does not exist, calculating the touch position of the user through a position calculation module; wherein, the system phase value of the position detection system is:
when there is no same-frequency noise, i.e. B is 0, then
The calculated system phase value of the position detection system is equal to the real system phase value of the position detection system;
when there is same frequency noise: i.e., B ≠ 0 and φ ≠ θ,
the noise judging module judges whether the same-frequency noise exists in the induction signal in the following manner: judging whether the calculated system phase value of the position detection system is equal to the real system phase value of the position detection system or not, and if the calculated system phase value of the position detection system is equal to the real system phase value of the position detection system, judging that the current induction signal does not have the same-frequency noise; and if the calculated system phase value of the position detection system is not equal to the real system phase value of the position detection system, judging that the same-frequency noise exists in the current induction signal.
The noise elimination module is used for calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value and eliminating the same-frequency noise in the driving signal frequency; the calculation mode of the noise-free mediation value of the driving signal frequency and the noise of the frequency nearby the driving signal frequency is specifically as follows: the sine wave signal coupled from the first electrode to the second electrode passes through the hanning window and has a sampling time T, and the frequency spectrum curve of the sampled signal is shown in fig. 2, which is a frequency spectrum curve graph of the sampled signal. Where f is the driving signal frequency, and bi tfreq is 1/T, which is regarded as the minimum variation unit of the driving signal frequency f in the position detection system. It is deduced from the curve theory that the influence coefficients of the demodulated values of the signal at the driving signal frequency f at five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq are respectively [0,0.5,1,0.5,0], and then the mutual influence relationship between the demodulated value at any frequency point and the demodulated value at the adjacent frequency point is as follows:
in formula (9) and formula (10), [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulated values of the five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq can be directly obtained by the demodulator. While
The noiseless demodulated value after the correction processing on the corresponding frequency point is the signal of the driving signal frequency f, and is obtained by calculation of formula (9) and formula (10).
The position calculation module is used for calculating the touch position of the user by using the induction signal demodulation value or the corrected noiseless demodulation value; as shown in fig. 4, the first electrode and the second electrode are multi-electrode arrays, the electrode arrays are arranged perpendicularly to each other, dense cross nodes are formed on the whole touch panel, and each cross node is regarded as a coupling capacitor. When a user touches the touch screen, the size of the coupling capacitor near the touch position can be changed, so that the touch position of the user can be calculated only by detecting the variable quantity of each capacitor. Specifically, a driving signal is loaded on the first electrode array of the first electrode, and simultaneously, the sensing signals on all the electrode arrays of the second electrode are detected and demodulated, and the demodulated value can be regarded as a cross-coupling capacitance value of the two electrodes. And sequentially finishing the loading of the driving signals of all the electrode arrays on the first electrode in the same way, so that all the cross coupling capacitance values of the touch panel plane can be obtained. The capacitance value when the user does not operate is set as a reference value, and when the user performs touch operation, the accurate touch position of the user can be quickly calculated by comparing the real-time value of the capacitance value with the reference value.
Fig. 5 is a schematic structural diagram of a co-frequency noise processing system according to an embodiment of the present invention. The same-frequency noise processing system comprises a position detection system and a same-frequency noise processing device, wherein the position detection system and the same-frequency noise processing device are connected with each other; the same-frequency noise processing device comprises a CPU controller, a modulator, a first electrode, a second electrode and a demodulator; the CPU controller is respectively connected with a modulator and a demodulator, the modulator is connected with the first electrode, and the demodulator is connected with the second electrode;
the CPU controller is used for controlling the modulator to load a driving signal on the first electrode, and the driving signal is coupled to the second electrode through the coupling capacitor between the first electrode and the second electrode to generate an induction signal; wherein, the step of controlling the modulator to load the driving signal on the first electrode by the CPU controller specifically comprises: the driving signal loaded on the first electrode is TX, then:
TX＝sin(ωt) (1)
in the formula (1), the first and second groups,
is the drive signal frequency f; the driving signal TX is coupled to the second electrode through the coupling capacitor between the first electrode and the second electrode, which may be equivalent to that the driving signal TX is communicated to the second electrode through a capacitive impedance, and then the sensing signal detected by the second electrode is RX:
Rx＝Asin(ωt+φ)+noise (2)
in formula (2), a and phi are the signal attenuation coefficient and the signal phase, i.e. the system phase of the position detection system, respectively; in general, the system phase phi of the position detection system is fixed and can be regarded as a known quantity, and then
noise＝Bsin(ωt+θ) (3)
In the formula (3), B and θ are respectively a noise attenuation coefficient and a noise phase, and the noise changes randomly, that is, B and θ represent random values.
The CPU controller is used for controlling the demodulator to demodulate the induction signal on the second electrode to obtain a demodulation value of the induction signal; the demodulation mode of the demodulator for demodulating the sensing signal on the second electrode specifically includes: and spreading the induction signal RX, wherein the expansion formula of the induction signal RX is as follows:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt) (4)
performing quadrature demodulation on the expanded sensing signal RX to obtain a cosine component (I value) and a sine component (Q value) of the sensing signal RX, and calculating an amplitude R of the sensing signal RX at the driving frequency f according to the cosine component and the sine component, wherein the specific formula is as follows:
I＝Acos(φ)+Bcos(θ) (5)
Q＝Asin(φ)+Bsin(θ) (6)
the CPU controller also comprises a noise judgment module, a noise elimination module and a position calculation module, wherein the noise judgment module, the noise elimination module and the position calculation module are sequentially connected;
the noise judgment module is used for calculating a system phase value arctan (Q/I) of the position detection system according to the demodulated value of the induction signal and judging whether the same-frequency noise exists in the sampling induction signal according to the calculated system phase value of the position detection system; if the same-frequency noise exists, acquiring a corrected noiseless demodulation value through a noise elimination module; if the same-frequency noise does not exist, calculating the touch position of the user through a position calculation module; wherein, the system phase value of the position detection system is:
when there is no same-frequency noise, i.e. B is 0, then
The calculated system phase value of the position detection system is equal to the real system phase value of the position detection system;
when there is same frequency noise: i.e., B ≠ 0 and φ ≠ θ,
the noise judging module judges whether the same-frequency noise exists in the current sensing signal in the following manner: acquiring a real system phase value of the position detection system, judging whether the calculated system phase value of the position detection system is equal to the real system phase value of the position detection system or not, and if the calculated system phase value of the position detection system is equal to the real system phase value of the position detection system, judging that the same-frequency noise does not exist in the current induction signal; and if the calculated system phase value of the position detection system is not equal to the real system phase value of the position detection system, judging that the same-frequency noise exists in the current induction signal.
The noise elimination module is used for calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value and eliminating the same-frequency noise in the driving signal frequency; the calculation mode of the noise-free mediation value of the driving signal frequency and the noise of the frequency nearby the driving signal frequency is specifically as follows: the sine wave signal coupled from the first electrode to the second electrode passes through the hanning window and has a sampling time T, and the frequency spectrum curve of the sampled signal is shown in fig. 2, which is a frequency spectrum curve graph of the sampled signal. Where f is the driving signal frequency, and bi tfreq is 1/T, which is regarded as the minimum variation unit of the driving signal frequency f in the position detection system. It is deduced from the above curve theory that the influence coefficients of the demodulated values of the signal at the driving signal frequency f at five frequency points f-2 × bi tfreq, f-bi tfreq, f + bi tfreq, and f +2 × bi tfreq are [0,0.5,1,0.5,0], respectively, and the mutual influence relationship between the demodulated value at any frequency point and the demodulated values at adjacent frequency points is:
in formula (9) and formula (10), [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulated values of the five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq can be directly obtained by the demodulator. While
The noiseless demodulated value after the correction processing on the corresponding frequency point is the signal of the driving signal frequency f, and is obtained by calculation of formula (9) and formula (10).
The position calculation module is used for calculating the touch position of the user by utilizing the sampled induction signal demodulation value or the corrected noiseless demodulation value.
The same-frequency noise processing method, the same-frequency noise processing device and the same-frequency noise processing system of the embodiment of the invention load the driving signal on the first electrode, acquire the demodulated value of the sine wave signal on the second electrode in an orthogonal demodulation mode, calculate the system phase according to the demodulated value, and judge whether the current induction signal contains the same-frequency noise according to the calculated value of the system phase, thereby solving the real-time problem of the same-frequency noise processing; and acquiring the modified drive signal and the noiseless demodulated value of the nearby frequency noise thereof by the mutual influence relationship between the demodulated value of any frequency point and the demodulated value of the adjacent frequency point, finally realizing noise elimination processing, effectively inhibiting the negative effect of the same frequency noise in the position detection system, and greatly improving the user experience.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A method for processing same-frequency noise comprises the following steps:
step a: loading a driving signal on the first electrode, wherein the driving signal is coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode to generate an induction signal;
step b: demodulating the induction signal on the second electrode, calculating a system phase value of the noise source system according to the demodulated value of the induction signal, judging whether the same-frequency noise exists in the current induction signal or not according to the calculated system phase value of the noise source system, and executing the step c if the same-frequency noise exists;
step c: and calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, and acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value to eliminate the same-frequency noise in the driving signal frequency.
2. The same-frequency noise processing method according to claim 1, characterized in that: in the step a, the driving signal applied to the first electrode is:
tx sin (ω t), the induced signal generated is:
Rx＝Asin(ωt+φ)+noise，
wherein, noise is Bsin (ω t + θ),
in the above formula, Tx is a driving signal, ω is 2 pi f, where f is a driving signal frequency, Rx is an induced signal, a is a signal attenuation coefficient, Φ is a signal phase, i.e., a system phase value of a noise source system, and B and θ are a noise attenuation coefficient and a noise phase, respectively.
3. The same-frequency noise processing method according to claim 2, characterized in that: in step b, the demodulation method for demodulating the sensing signal on the second electrode specifically includes: unfolding the induction signal Rx, carrying out orthogonal demodulation on the unfolded induction signal Rx to obtain a cosine component and a sine component of the induction signal Rx, and calculating the amplitude R of the induction signal Rx at the driving frequency f according to the cosine component and the sine component; the induction signal Rx expansion formula is as follows:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt)
in the above formula, B and θ are respectively a noise attenuation coefficient and a noise phase;
the specific formula for obtaining the cosine component and the sine component and calculating the amplitude R of the induction signal Rx at the driving frequency f according to the cosine component and the sine component is as follows:
I＝Acos(φ)+Bcos(θ)
Q＝Asin(φ)+Bsin(θ)
in the above formula, I is a cosine component and Q is a sine component.
4. The same-frequency noise processing method according to claim 3, characterized in that: in the step b, the judging manner of judging whether the same-frequency noise exists in the current sensing signal according to the calculated system phase value of the noise source system is as follows: judging whether the system phase value of the noise source system calculated in the step b is equal to the real system phase value of the noise source system, and if the system phase value of the noise source system calculated in the step b is equal to the real system phase value of the noise source system, judging that the same-frequency noise does not exist in the current induction signal; and c, if the system phase value of the noise source system calculated in the step b is not equal to the real system phase value of the noise source system, judging that the same-frequency noise exists in the current induction signal.
5. The same-frequency noise processing method according to claim 4, characterized in that: in the step c, the calculation method for obtaining the noise-free demodulated value of the modified driving signal frequency and the noise of the frequency near the modified driving signal frequency according to the noise quantized value specifically includes: a driving signal which is coupled to a second electrode from a first electrode passes through a Hanning window, the sampling time is T, f is the frequency of the driving signal, bitfreq is 1/T, and bitfreq is the minimum variation unit of the frequency f of the driving signal; the influence coefficients of the demodulated values of the signal with the driving signal frequency f at five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq are respectively [0,0.5,1,0.5,0], and then the mutual influence relation formula of the demodulated value of any frequency point and the demodulated value of the adjacent frequency point is as follows:
in the above formula, [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulation values of five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq are respectively,
and modifying the processed noiseless demodulated value of the signal with the driving signal frequency f at the corresponding frequency point.
6. A same-frequency noise processing device is characterized in that: the device comprises a CPU controller, a modulator, a first electrode, a second electrode and a demodulator; the CPU controller is used for controlling the modulator-demodulator to load a driving signal on the first electrode, and the driving signal is coupled to the second electrode through a coupling capacitor between the first electrode and the second electrode to generate an induction signal;
the CPU controller control demodulator demodulates the induction signal on the second electrode;
the CPU controller calculates a system phase value of the noise source system according to the demodulated value of the induction signal, and judges whether the same-frequency noise exists in the current induction signal or not according to the calculated system phase value of the noise source system; if the same-frequency noise exists, calculating the noise quantization value of the driving signal frequency and the noise of the nearby frequency according to the mutual influence relation between the demodulation value of any frequency point and the demodulation value of the adjacent frequency point, acquiring the corrected noise-free demodulation value of the driving signal frequency and the noise of the nearby frequency according to the noise quantization value, and eliminating the same-frequency noise in the driving signal frequency.
7. The on-channel noise processing apparatus according to claim 6, wherein: the demodulation mode of the demodulator for demodulating the induction signal on the second electrode specifically comprises the following steps: unfolding the induction signal Rx, carrying out orthogonal demodulation on the unfolded induction signal Rx to obtain a cosine component and a sine component of the induction signal Rx, and calculating the amplitude R of the induction signal Rx at the driving frequency f according to the cosine component and the sine component; the induction signal Rx expansion formula is as follows:
Rx＝Asin(ωt+φ)+Bsin(ωt+θ)
＝(Acos(φ)+Bcos(θ))sin(ωt)+(Asin(φ)+Bsin(θ))cos(ωt)
in the above formula, ω ═ 2 pi f, where f is the drive signal frequency, a, Φ are the signal attenuation coefficient and the signal phase, respectively, and B, θ are the noise attenuation coefficient and the noise phase, respectively;
the specific formula for obtaining the cosine component and the sine component and calculating the amplitude R of the induction signal Rx at the driving frequency f according to the cosine component and the sine component is as follows:
I＝Acos(φ)+Bcos(θ)
Q＝Asin(φ)+Bsin(θ)
in the above formula, I is a cosine component and Q is a sine component.
8. The on-channel noise processing apparatus according to claim 7, wherein: the CPU controller judges whether the same-frequency noise exists in the current induction signal in the following manner: judging whether the calculated system phase value of the noise source system is equal to the real system phase value of the noise source system or not, and if the calculated system phase value of the noise source system is equal to the real system phase value of the noise source system, judging that the same-frequency noise does not exist in the current sensing signal; and if the calculated system phase value of the noise source system is not equal to the real system phase value of the noise source system, judging that the same-frequency noise exists in the current sensing signal.
9. The on-channel noise processing apparatus according to claim 8, wherein: the CPU controller calculates a noise quantization value of the driving signal frequency and the noise of the frequency nearby, and the calculation mode of acquiring the corrected noise demodulation value of the driving signal frequency and the noise of the frequency nearby according to the noise quantization value is as follows: a driving signal which is coupled to a second electrode from a first electrode passes through a Hanning window, the sampling time is T, f is the frequency of the driving signal, bitfreq is 1/T, and bitfreq is the minimum variation unit of the frequency f of the driving signal; the influence coefficients of the demodulated values of the signal with the driving signal frequency f at five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq are respectively [0,0.5,1,0.5,0], and then the mutual influence relation formula of the demodulated value of any frequency point and the demodulated value of the adjacent frequency point is as follows:
in the above formula, [ R ]
-2,R
-1,R
0,R
+1,R
+2]The demodulation values of five frequency points of f-2 × bitfreq, f-bitfreq, f + bitfreq and f +2 × bitfreq are respectively,
and modifying the processed noiseless demodulated value of the signal with the driving signal frequency f at the corresponding frequency point.
10. A same-frequency noise processing system comprises a noise source system, and is characterized in that: the co-channel noise processing device of any one of claims 6 to 9, wherein the noise source system is in signal connection with the co-channel noise processing device; and eliminating the same-frequency noise in the noise source system through the same-frequency noise processing device.
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