CN110739953B

CN110739953B - Scene type signal self-adaptive processing method of capacitive touch key and electronic device

Info

Publication number: CN110739953B
Application number: CN201910993494.0A
Authority: CN
Inventors: 周留洋
Original assignee: Sichuan Zhongwei Xincheng Technology Co ltd
Current assignee: Sichuan Zhongwei Xincheng Technology Co ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2023-05-09
Anticipated expiration: 2039-10-18
Also published as: CN110739953A

Abstract

The invention provides a scene type signal self-adaptive processing method of a capacitive touch key and an electronic device. The scene signal self-adaptive processing method is performed by using a touch detection controller to collect touch signals; the signal preprocessor preprocesses the signals; the signal scene classifier classifies the signal scenes of the processed signals; the signal scene memory stores the current signal scene; the signal scene comparator compares the current signal scene with the previous signal scene; signal processing is carried out by using an intra-scene processor according to the comparison result, or signal scene switching and processing are carried out by using an inter-scene processor; and the processed signals are gathered into a key information judging device for processing. The scene signal self-adaptive processing method analyzes and switches each signal scene, so that the touch electronic device performs omnibearing analysis processing on the signals, the signal self-adaptive processing or switching processing is realized, and the self-adaptation of key touch judgment information under various signal scenes is ensured.

Description

Scene type signal self-adaptive processing method of capacitive touch key and electronic device

Technical Field

The present invention relates to the field of signal processing and control, and in particular, to a scene-type signal adaptive processing method for capacitive touch keys and an electronic device.

Background

With the increasing popularity of capacitive touch keys on electronic products such as household appliances, more and more users operate the electronic products through the capacitive touch keys so as to enjoy convenience brought by the capacitive touch keys for life. Meanwhile, the capacitive touch keys have the advantages of being friendly in operation, novel in interface and the like, are rapidly replacing the traditional keys, and become the main stream of the market.

However, due to the universality of the use scene of the electronic product, such as different altitudes, different air pressures, different environment temperatures, different environment humidity, different regional environments and the like, the capacitive touch key is extremely susceptible to various influences due to the characteristics of the capacitor, so that the capacitive signal is unstable.

Wherein:

ε ₀ air dielectric constant

ε _r Relative permittivity of cover layer =

A = contact area of finger with sensor pad cover

d = cover layer thickness

C _F Is the finger capacitance.

Changes in the touch environment, such as temperature, humidity, etc., will cause the capacitance signal to drift slowly and slightly, but continuously, with changes in the environment; such as the cleanliness of the touch surface (e.g., water drops, oil stains), will cause the capacitive signal to suddenly shift up or down and then remain; for example, a ripple of a single source of the system will cause the capacitance signal to fluctuate as the ripple fluctuates; for example, noise and interference caused by other devices in the surrounding environment (such as radio frequency signals of mobile phones and electromagnetic signals of microwave ovens) can cause instantaneous rapid and violent changes of capacitance signals due to interference; even thermal noise caused by the manufacturing process of the chip itself can cause the capacitance signal to shake up and down rapidly with small amplitude.

In the operation process, the detection unit stores untouched capacitance values (reference values) for each touch key, and when the latest capacitance value (sensing value) is received subsequently, the received sensing value is compared with the corresponding judging reference value to judge whether the key is touched or not. The instability of the capacitance signal in the above-mentioned various scenes increases the difficulty of correctly judging whether the key is touched.

In the prior art, some of the detection methods detect the jitter of the power supply ripple by adopting AD sampling, and different processing modes are adopted according to the jitter, for example, some detection methods detect the occurrence of interference by adopting a special interference detection circuit, so that the detection of touch avoids the interference in time. The problem in the above-mentioned technology is that, for example, adding an external interference detection circuit means increasing the cost, indirectly analyzing the related interference signal without directly analyzing the capacitance signal itself, which results in imperfect analysis and processing of the signal, and finally, misjudgment as to whether the key is touched.

Disclosure of Invention

In order to solve the defects of the prior art in the background art, the invention provides a scene type signal self-adaptive processing method of a capacitive touch key and an electronic device.

In a first aspect, the present invention provides a method for adaptively processing a scene-type signal of a capacitive touch key.

Acquiring touch key signals to obtain a current signal sensing value, wherein the sensing value is the number of pulses in a certain time; classifying the signal scenes according to the change rate, the change strength and the change duration of the sensing value, and determining the current signal scene; storing a current signal scene; comparing the current signal scene with the last signal scene to determine whether the scene changes; if the signal scene is unchanged, using a signal processing mode of the same scene; if the signal scene is changed, switching the scene, and using a signal processing mode of the new scene; and performing key signal processing according to the signal processing mode.

Further, the acquisition of the touch key signals can adopt a relaxation oscillation frequency measurement method or a charge transmission measurement method to detect the touch signals.

Preferably, after the touch key signals are collected, the signals can be preprocessed, wherein the preprocessing is specifically two-stage processing, the first-stage processing is sliding window dynamic tracking filtering, and the second-stage processing is inertial filtering.

One implementation of the sliding window dynamic tracking filtering may be: n sensing values obtained continuously are regarded as a queue, the length of the queue is fixed to be N, and N data in the queue is subjected to arithmetic average operation by adopting a first-in first-out principle, so that a new filtering result is obtained.

One implementation of inertial filtering may be: the following formula was used for filtering

Current filtering result= (1-a) current signal value + a last filtering result

Wherein, the value range of a is between 0 and 1.

Preferably, the rate of change, the intensity of change, and the duration of change are specifically: continuously collecting sensing values, recording the ith sensing value as Data [ i ], measuring the sensing variable sigma [ i ] =data [ i ] -Data [ i-1] for the ith time, and accumulating the sensing variable sigma [ i ] to sigma, wherein sigma is initialized to 0; until i reaches a preset maximum acquisition time, or the absolute value of sigma i is smaller than a preset first threshold; the rate of change is sigma/N, the intensity of change is the absolute value of sigma, and the time of change is i times the single acquisition time.

Preferably, classifying the signal scene according to the rate of change, the intensity of the change, and the duration of the change of the sensed value comprises at least one of the following:

first signal scenario: the change rate is negative, the change intensity is smaller than the noise line, and the duration time is the first signal scene time T1;

Second signal scenario: the change rate is positive, the change intensity is smaller than that of the upper noise line, and the duration time is the second signal scene time T2;

third signal scenario: the sensing value dithers up and down in the upper and lower noise line ranges;

fourth signal scenario: the change rate is positive, the change intensity is larger than the upper noise line and smaller than the maximum signal line, and the duration time is the fourth signal scene time T4;

fifth signal scenario: the change rate is positive, the change intensity is larger than the maximum signal line, and the duration is the fifth signal scene time T5;

sixth signal scenario: the change rate is negative, the change intensity is larger than the lower noise line and smaller than the touch line, and the duration is the sixth signal scene time T6;

seventh signal scenario: the change rate is negative, the change intensity is larger than the touch line and smaller than the minimum signal line, and the duration is the seventh signal scene time T7;

eighth signal scenario: the change rate is negative, the change intensity is larger than the minimum signal line, and the duration is eighth signal scene time T8;

wherein the minimum signal line < noise line below < touch line < reference line < noise line above < maximum signal line;

the touch line is a threshold line for judging that the key is touched under ideal conditions;

the reference line is determined by the sensed value when the key is not touched in an ideal case.

It should be noted that, for different products, the above scenes may occur at the same time, or only a part of them may be selected.

The signal processing method using the new scene comprises the following steps:

when the current scene is determined to be a first signal scene, the reference line = reference line-first signal scene constant, the first scene constant taking down between 0.2 and 0.5 times the difference between the noise line and the reference line;

when the current scene is determined to be a second signal scene, the reference line=reference line+a second signal scene constant, the second signal scene constant taking down between 0.3 and 0.6 times the difference between the noise line and the reference line;

when the current scene is determined to be the third signal scene, reference line = reference line;

when the current scene is determined to be a fourth signal scene, the reference line=reference line+fourth signal scene constant, wherein the fourth signal scene constant is between 0.2 and 0.5 times of the difference value between the sensing line and the reference line;

when the current scene is determined to be a fifth signal scene, the reference line=the reference line+a fifth signal scene constant, wherein the fifth signal scene constant is between 0.6 and 0.8 times of the difference value between the sensing line and the reference line;

when the current scene is determined to be a sixth signal scene, the reference line=reference line-a sixth signal scene constant, the sixth signal scene constant taking between 0.6 and 0.8 times the difference between the sensing line and the reference line;

When the current scene is determined to be a seventh signal scene, testing touch generation, and not adjusting a reference line;

when the current scene is determined to be the eighth signal scene, the reference line=the sense line, which is determined by the sense value.

It should be noted that the above-mentioned treatment methods are not necessarily all required, and may be selectively combined according to the requirements of the product.

Further, after the reference line is redetermined, the minimum signal line, the lower noise line, the touch line, the upper noise line, and the maximum signal line are redetermined according to differences or ratios of the original minimum signal line, the original lower noise line, the original touch line, the original upper noise line, and the original maximum signal line to the original reference line.

Further, the key signal processing according to the signal processing manner may be that the key is determined to be pressed when the sensing value is greater than the touch line within a certain time, otherwise, the key is determined to be not pressed.

The present invention also provides an electronic device including: the touch detection device comprises one or more touch switches, a touch detection unit, a signal scene classification unit, a signal scene storage unit, a scene comparison unit, an in-scene processing unit, an inter-scene processing unit and a key information judging unit; wherein, the liquid crystal display device comprises a liquid crystal display device,

The touch detection unit is used for acquiring touch key signals to obtain a current signal sensing value, wherein the sensing value is the number of pulses in a certain time;

the signal scene classification unit is used for classifying the signal scenes according to the change rate, the change strength and the change duration of the sensing value and determining the current signal scene;

the signal scene storage unit is used for storing the current signal scene;

the scene comparison unit is used for comparing the current signal scene with the last signal scene and determining whether the scene is changed or not;

the in-scene processing unit is used for using the signal processing mode of the same scene if the signal scene is unchanged;

the inter-scene processing unit is used for switching the scenes if the signal scenes are changed and using the signal processing mode of the new scenes;

and the key information judging unit is used for carrying out key signal processing according to the signal processing mode.

According to the scene type signal self-adaptive processing method, through analysis of each scene of the signal and switching processing of the signal scenes, the touch electronic device can conduct all-round analysis and processing on the signal, self-adaptive processing of the signal in the current signal scene and self-adaptive switching and processing among the signal scenes are achieved, and therefore self-adaptation of key touch judgment information under various signal scenes is guaranteed.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are some embodiments of the invention and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a touch circuit based on RC (relaxation oscillation frequency) measurement method;

FIG. 2 is a schematic diagram of touch signals based on RC (relaxation oscillation frequency) measurement method;

FIG. 3 is a schematic diagram of touch data based on RC (relaxation oscillation frequency) measurement method;

FIG. 4 is a schematic diagram of a touch circuit based on a charge transfer measurement method;

FIG. 5 is a schematic diagram of touch signals based on a charge transfer measurement method;

FIG. 6 is a schematic diagram of touch data based on a charge transfer measurement method;

FIG. 7 is a block diagram of a scene-type signal adaptive touch switch system and electronic device;

FIG. 8 is one embodiment of a touch detection controller based on an RC (relaxation oscillation frequency) measurement method;

FIG. 9 is one embodiment of a touch detection controller based on a charge transfer measurement method;

FIG. 10 is a schematic diagram of a signal preprocessor;

FIG. 11 is a reference line change schematic;

FIG. 12 scene classification flow chart;

FIG. 13 is a schematic diagram of signal scene classification;

fig. 14 is a signal scene transition diagram.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings and specific examples. It should be noted that the described embodiments are some, but not all embodiments of the present invention, and all other embodiments obtained by persons skilled in the art without making any inventive effort are within the scope of the present invention based on the embodiments in the present invention.

The measuring method of the capacitive touch key signal mainly comprises an RC-based measuring method and a charge transmission-based measuring method, wherein the RC-based measuring method can adopt a relaxation oscillation frequency measuring method, the charge transmission-based measuring method can adopt a charge transmission capacitance sensing technology, and the main principle is that capacitance changes caused by human finger touch are converted into numerical changes such as current, voltage, frequency and time, and the numerical values can be increased or reduced by human finger touch according to a specific implementation mode.

The basic principle of each of the above-described touch signal measurement methods is explained in turn as follows.

(1) RC-based measurement method and relaxation oscillation frequency measurement method

The basic principle of "Relaxation oscillation" (Relaxation 0 scillator) touch detection is a Relaxation oscillator that is constantly charged and discharged. A touch detection circuit diagram constructed based on the "relaxation oscillation" principle as shown in fig. 1, the relaxation oscillator has a fixed basic charge-discharge period (frequency) depending on the parasitic capacitance Cp and resistance R equivalent if the electrodes are not touched; if the electrode is touched by a finger, an electric field effect is generated between the finger and the electrode to parasitize a finger capacitor Cf, the finger capacitor Cf is overlapped with the original parasitic capacitor Cp of the key, the charge and discharge period of the relaxation oscillator is prolonged, and the frequency is correspondingly reduced. As shown in fig. 1, a touch detection circuit diagram based on the "relaxation oscillation" principle is shown, wherein a parasitic capacitance Cp is a capacitance when a capacitive touch key is not touched, when a positive terminal voltage Vref of a comparator is higher than a negative terminal voltage of the comparator, VOUT output is at a high level, and at this time, an output terminal VOUT of the comparator charges the parasitic capacitance Cp through a resistor R equivalent, so that the negative terminal voltage of the comparator increases: when the negative terminal voltage of the comparator is higher than the positive terminal voltage, the output of the VOUT is low, and the parasitic capacitance Cp is equivalently discharged through the resistor R, so that the negative terminal voltage of the comparator is reduced, and when the negative terminal voltage is lower than the positive terminal voltage, the output of the VOUT is restored to the high level. When the capacitance change parasitic capacitance Cp of the capacitive touch key overlaps the finger capacitance Cf (with finger touch), the frequency of the rectangular oscillation wave will also change with the change of the RC time constant.

If a measurement period t1 is determined using the reference clock as shown in fig. 2, and the oscillator output frequency is counted during the measurement period t1, a touch event can be detected, and as shown in fig. 2, the count value at the time of touch is less than the count value at the time of no touch during the same measurement period; if the reference clock is clocked when the same number of pulses is output by the oscillator, a touch event may be detected, as shown in fig. 2, in which the number of pulses is the same, the time value t1 at the time of touch is greater than the time value t0 at the time of no touch.

As shown in fig. 3, the change condition of the data when touching and not touching is observed from the angle of the time domain: for a measurement mode of using a reference clock to determine a measurement time period and counting the output frequency of the oscillator in the measurement time period, it can be seen that the count value when touching is less than the count value when not touching, and the touch data grows downwards; if the reference clock is clocked when the same number of pulses is output by the oscillator, it can be seen that the clocked value at the touch is greater than the clocked value at the non-touch, and the touch data grows upward.

(2) Charge transfer-based measurement method-charge transfer capacitance sensing technique

The basic principle of the charge transfer capacitance sensing technique can be illustrated by means of fig. 4: if the electrode is not touched, cp represents the parasitic capacitance of the capacitive touch electrode, and switch K1 is first closed to charge parasitic capacitance Cp: when the parasitic capacitance Cp is fully charged, the switch K1 is opened, and the switch K2 is closed, so that charge is transferred between the parasitic capacitance Cp and the detection capacitance Cs, and the detection capacitance Cs is charged. The above charging and charge transfer operations are repeated, the voltage at the upper electrode plate V of the detection capacitor Cs gradually increases, and when the voltage at the V point increases to Vref, the charging cycle of one detection capacitor Cs ends. If the electrode is touched by a finger, an electric field effect is generated between the finger and the electrode to parasitize a finger capacitor Cf, the finger capacitor Cf is overlapped with the original parasitic capacitor Cp of the key, after the parasitic capacitor Cp and the finger capacitor Cf are charged by closing the switch K1, more charges are accumulated in the parasitic capacitor Cp and the finger capacitor Cf, so that the charge is transferred at a higher speed when the parasitic capacitor Cp and the finger capacitor Cf transfer the capacitance to the detection capacitor Cs, the charging period (the charge transfer frequency) is shortened, the output turnover of the comparator is faster, and the output frequency is correspondingly increased.

FIG. 5 shows waveforms of the voltage at the V point in the whole charging period, if a reference clock is used to determine a measurement period t2, and the output frequency (number of pulses) of the comparator is counted in the measurement period t2, then a touch event can be detected, as shown in FIG. 5, in the same measurement period t2, the count value (number of pulses) at the time of touch is greater than the count value (number of pulses) at the time of no touch; if the reference clock is clocked when the comparator outputs the same number of pulses, a touch event may be detected, as shown in fig. 5, in which the clocked value t0 at the time of touch is smaller than the clocked value t1 at the time of no touch. Typically, cs is set to a value over thousands of times Cx to ensure good capacitive resolution.

As shown in fig. 6, the change of the data between the touch and the non-touch is observed from the perspective of the time domain: for determining a measurement time period by using the reference clock, and for the measurement mode that the output frequency (the number of pulses) of the comparator is counted in the measurement time period, it can be seen that the count value when touching is more than the count value when not touching, and the touch data grows upwards; if the reference clock is clocked when the comparator outputs the same number of pulses, it can be seen that the clocked value at the touch is less than the clocked value at the non-touch, and the touch data grows downward.

As described above, regardless of the RC-based frequency measurement method or the charge-based transmission measurement method, the capacitance change caused when a human finger touches can be eventually converted into a corresponding change in touch data, which can be grown up or up, and once one mode is selected, the growth direction is fixed, i.e., the data either decreases or increases when touched.

FIG. 7 is a flowchart of a method for processing information of a scene type signal adaptive touch switch, wherein touch key signals are acquired through a touch detection controller to obtain a current signal sensing value, and the sensing value is the number of pulses in a certain time;

then preprocessing the acquired signals by using a signal preprocessor;

then, a signal scene classifier is used for classifying the signal scenes according to the change rate, the change strength and the change duration of the sensing value, and the current signal scene is determined;

then using a signal scene memory to store the current signal scene;

after storing the current signal scene, comparing the current signal scene with the last signal scene by using a scene comparator to determine whether the scene changes;

if the signal scene is unchanged, using a signal processing mode of a processor in the scene for the same scene;

If the signal scene changes, switching the scene, switching to a new scene by using an inter-scene processor and performing signal processing;

and finally, performing key signal processing according to the signal processing mode by using a key information determiner.

It should be noted that the signal preprocessor is not necessary, and whether to use the preprocessor may be determined according to the requirement of accuracy.

The touch detection unit comprises N touch detection channels, each touch detection channel is provided with a corresponding touch detection element, and the touch detection elements can be electrodes, springs, bonding pads or other similar devices capable of realizing touch detection;

touch detection controller: the implementation of the touch detection controller may vary, but its main function is substantially the same, whether it is an RC-based frequency measurement method or a charge-based transmission measurement method.

As described in one embodiment of the touch detection controller based on RC (relaxation oscillation frequency) measurement method of fig. 8: the touch channel adopts an analog switch mode to realize channel switching; the touch oscillator, see fig. 1 for a schematic diagram of a touch circuit based on an RC (relaxation oscillation frequency) measurement method, is used for implementing charge and discharge control on a touch detection element, detecting a change of an oscillation frequency, and analog filtering is used for implementing filtering of an oscillation frequency unstable signal, where a reference voltage division may be provided to different negative terminal comparison voltages of a comparator, such as 0.4×power supply voltage, 0.5×power supply voltage, 0.6×power supply voltage, and 0.7×power supply voltage; the Comparator (COMP) converts the voltage change on the detection capacitor into pulse waveform output, and after the possible burrs on the pulse waveform are filtered out through digital filtering, the pulse waveform is sent to the touch counter for counting; the time slot counter generates a counting interval for the touch counter; the clock of the time slot counter can be provided by a TKOSC (touch clock) or Fsys system clock, and is selected by a TKOSC_SLE (clock selector) and provided for the touch counter to use after being divided by a prescaler, wherein the prescaler divides the selected clock (one of the TKOSC (touch clock) or the Fsys system clock), and the conventional dividing coefficient is generally 1 division, 2 division, 4 division, 8 division and the like.

As described in one embodiment of the touch detection controller based on the charge transfer measurement method of fig. 9: the touch channel adopts an analog switch mode to realize channel switching; the capacitive charge conversion, see fig. 4 for a schematic diagram of a touch circuit based on a charge transmission measurement method, is used for implementing charge and discharge control on a touch detection element, a detection capacitor is used for implementing charge collection, analog filtering is used for implementing filtering of unstable charges on the detection capacitor, and a reference voltage division can be provided for different negative comparison voltages of a comparator, such as 0.4 x power supply voltage, 0.5 x power supply voltage, 0.6 x power supply voltage and 0.7 x power supply voltage; a Comparator (COMP) converts the voltage change on the detection capacitor into a pulse waveform to be output, and after the result is digitally filtered out burrs possibly existing on the pulse waveform, the burrs are sent to a touch counter for counting; the time slot counter generates a counting interval for the touch counter; the clock of the time slot counter can be provided by a TKOSC (touch clock) or Fsys system clock, and is selected by a TKOSC_SLE (clock selector) and provided for the touch counter to use after being divided by a prescaler, wherein the prescaler divides the selected clock (one of the TKOSC (touch clock) or the Fsys system clock), and the conventional dividing coefficient is generally 1 division, 2 division, 4 division, 8 division and the like.

As shown in the schematic diagram of the signal preprocessor of fig. 10, the signal preprocessor is used to preprocess the signal: the specific implementation can be two-stage processing, wherein the first-stage processing is sliding window dynamic tracking filtering, the second-stage processing is inertial filtering, periodic interference data are filtered through the first-stage processing, periodic and aperiodic pulse interference data are filtered through the second-stage processing, the output of the result of the first-stage processing is used as the input of the second-stage processing, and the output of the result of the second-stage processing is used as the input of the signal scene classifier. Of course, other more complex and better filtering algorithms may be used if processing power allows.

The dynamic tracking method of the sliding window comprises the following implementation processes: the N sensing values obtained continuously are regarded as a queue, the length of the queue is fixed to be N, new data are sampled each time and put into the tail of the queue, primary data of the original queue head are thrown out, namely a first-in first-out principle, and the N data in the queue are subjected to arithmetic average operation to obtain a new filtering result. The value of N is generally 2-16, and in one embodiment, N is 5. The specific implementation mode is that, in the first step of acquisition: sequentially collecting N times of data, and calculating TouchDataMean, touchDataMean. = (TouchData 1+TouchData2+ … +TouchDataN)/N for the data collected from the first time to the nth time (total N data); and in the second step of collection: collecting the data once, collecting the data of the (n+1) th time, discarding the data of the (1) th time, and simultaneously sequentially advancing the data of the (2) th time to the (N) th time, namely, changing the data of the (2) th time to the (N) th time into the data of the (1) th time to the (N-1) th time, changing the data of the (N-1) th time newly collected into the data of the (N) th time, and calculating a new TouchDataMean, touchDataMean. = (TouchDat1+TouchDat2+ … +TouchDataN)/N for the data collected from the current first time to the (total N data); by the sliding window dynamic tracking method, the arithmetic average value of the latest N data is used as a new TouchDataMean, so that dynamic tracking is performed, the reliability, the instantaneity and the accuracy of detection are ensured, and the influence of interference on key sensing value detection is avoided and reduced to the greatest extent.

Inertial filtering is also called first order low pass filtering or first order lag filtering, and the formula is as follows: the filtering result of this time= (1-a) the sampling value of this time+a the last filtering result, wherein, the value range of a is between 0 and 1, namely result n= (1-a) the touchdatamean+a is obtained by result N-1, result N is the filtering result of the current data, touchDataMean is the value of the current sampling value after the first stage processing, result N is the filtering result a of the current data can be 0.8, and result N-1 is the last filtering result.

The touch data after signal preprocessing has higher reliability, and is convenient for the use of a subsequent signal scene classifier. As described above, the change of the touch data converted from the capacitance change caused by touching the finger of the human body may be upward growth or upward growth, and for convenience, the downward growth will be explained by taking the downward growth as an example, and the upward growth is similar to the downward growth, and can be obtained by simply transforming according to the example herein, so that the invention is also within the protection scope of the present invention.

As shown in the reference line change schematic diagram of fig. 11, when no finger touches and no environment is disturbed, the signal value can also be called as a reference value when an ideal environment is provided, the curve drawn by the reference value along with time is called a reference line, and the reference value and the reference line are kept unchanged when the finger touches; the real-time signal values of finger touch and non-touch are called sensing values, and the curve drawn by the sensing values along with time is called sensing line.

In the operation process, the detection unit detects a signal value (reference value) when each touch key is not touched, and when the latest signal value (sensing value) is subsequently received, the received sensing value is compared with the reference value to judge whether the key is touched or not. Theoretically, when no finger touches, the sensing line is a smooth straight line, when a finger touches, the signal grows downwards, if the sensing value when touching is subtracted from the reference value when no finger touches, a difference value is generated, and when the difference value is large enough, the finger touches are considered. In fact, the reference line in the case of no finger touch is a curve after noise is superimposed due to various reasons of the system and environment, but the sensing value in the case of finger touch is obviously larger than the noise value, and the finger touch can be still recognized.

Due to the universality of the use scene of the electronic product, such as different altitudes, different air pressures, different environment temperatures, different environment humidity, different regional environments and the like, the capacitive touch key is extremely susceptible to various influences due to the characteristics of the capacitor, and the reference line is unstable.

Changes in the touch environment, such as temperature, humidity, etc., will cause the reference line to drift slowly and slightly but continuously as the environment changes; such as the cleanliness of the touch surface (e.g., water drops, oil stains), will cause the reference line to suddenly shift up or down; for example, a ripple of a system single source will cause the signal line to fluctuate with ripple fluctuations; for example, noise and interference caused by other devices in the surrounding environment (such as radio frequency signals of mobile phones and electromagnetic signals of microwave ovens) can cause instantaneous rapid and violent changes of a reference line due to interference; even thermal noise caused by the manufacturing process of the chip itself can cause the reference line to shake up and down rapidly with small amplitude.

Because the reference line reflects the sensing condition of the capacitance signal when not touched, the reference line should change along with the change of the actual environment, otherwise, the instability of the reference line in the various scenes can greatly increase the difficulty of correctly judging whether the key is touched, and the situation of false triggering or non-triggering is most likely to occur.

The touch switch system and the electronic device continuously correct the reference value to accommodate changes in environmental operating conditions. For example, when a touch key warms up, a change in capacitance is caused, eventually leading to an increase or decrease in the touch reference value. To accommodate these changes in the reference value, the touch switch system and the electronic device need to gradually follow the environmental changes to adjust the reference value.

Some signal scenarios may cause correction of reference values that lead to abnormal behavior. For example, if water or some other conductive liquid is sprayed onto the touch keys, the continuous correction procedure may be adjusted to this situation so that a touch event is falsely reported when water is removed.

As shown in fig. 11 with reference to the line change schematic, this figure is a time plot of exemplary sensed values (touch data) representing data on a key that may be from a capacitive touch key device. The Y-axis in fig. 11 represents the count value, and the sensed value is a value after preprocessing. The X-axis refers to samples taken at different points in time, which represent samples repeatedly acquired by a touch detection controller controlling a touch detection unit. The 701 sense line is made up of a plurality of sense values. The reference line 702 generally follows the trend of the sense line 701 curve.

When the sense line exceeds the touch line, the reference line will not update the baseline for the duration of the touch event, T0+T1, as a touch.

Consider the case where the reference line does not change with environmental changes: as shown at 704, the sense line drifts upward, e.g., the signal scene of a change in ambient temperature, although the reference line 702 remains unchanged, it is not misinterpreted as a touch at this time due to the upward drift. Then, some scenarios, such as dripping, may cause the sense line to slowly and continuously step down, such as 705, the reference line 702 remains unchanged due to the failure of the touch system to recognize the change in the environment, as shown in 706, and after accumulating for a certain time, the sense line exceeds the touch line, which is misinterpreted as a touch.

Consider the case where the reference line changes with environmental changes: as shown at 704, the touch system slowly adjusts the desired reference line 703 over time to compensate for changes in the operating environment (e.g., temperature) when the desired reference line rises following the rise of the sense line and is not misinterpreted as a touch. When some scenes such as dripping occur, the sensing line slowly and continuously drops gradually, as in 705, since the touch system can recognize the change of the signal environment, the expected reference line 703 changes along with the change of the sensing line, and in the case that the touch threshold is unchanged (that is, the dropping amplitude of the signal is unchanged when touching), the expected touch line 707 also changes along with the change of the expected reference line, so the sensing line does not exceed the touch line, and no false touch judgment exists at this time.

The method has the advantages that the signal scene is identified through analysis of the signal, and different processing is carried out on the reference line according to the signal scene where the signal is located, so that the reference line is ensured to change along with the change of the environment, wherein the identification of the signal scene is realized by the signal scene classifier.

Due to the fact that different actual environments lead to different signal scenes, finally, sensed values in different signal scenes are different, and the three dimensions of the change rate, the change strength and the duration of the sensed values relative to the reference values are reflected: the change rate alpha is determined by the change intensity in the change time T0 and the change intensity in the change time T0, and the larger the change intensity in the same T0 is, the larger the change rate is; varying intensity and duration T1 thereof.

In order to accurately define the variation intensity, the range of variation intensity needs to be defined according to the touch system, and as shown in the signal scene classification diagram of fig. 13, the signal scene classification diagram further includes a minimum signal line, a maximum signal line, a lower noise line and an upper noise line in addition to the reference line and the touch line. After the scenes of the signals are identified through three dimensions, different self-adaptive processing can be performed on the reference values aiming at different scenes, and the accuracy of touch detection is improved.

As shown in the signal scene classification diagram of fig. 13, 8 signal scenes can be abstracted:

first signal scenario: the sensing line is negatively changed relative to the reference line, the change intensity is smaller than that of the noise line, and the duration time is the first signal scene time T1;

second signal scenario: the sensing line positively changes relative to the reference line, the change intensity is smaller than that of the upper noise line, and the duration time is the second signal scene time T2;

third signal scenario: the sensing line is dithered up and down in the range of the upper noise line and the lower noise line relative to the reference line;

fourth signal scenario: the sensing line is positively changed relative to the reference line, the change intensity is larger than the upper noise line and smaller than the maximum signal line, and the duration time is the fourth signal scene time T4;

Fifth signal scenario: the sensing line is positively changed relative to the reference line, the change intensity is larger than the maximum signal line, and the duration time is the fifth signal scene time T5;

sixth signal scenario: the sensing line is negatively changed relative to the reference line, the change intensity is larger than the lower noise line and smaller than the touch line, and the duration time is the sixth signal scene time T6;

seventh signal scenario: the sensing line is in negative direction change relative to the reference line, the change intensity is larger than that of the touch line and smaller than that of the minimum signal line, and the duration time is the seventh signal scene time T7;

eighth signal scenario: the sensing line is negatively changed relative to the reference line, the change intensity is larger than that of the minimum signal line, and the duration time is the eighth signal scene time T8;

a description is made of the signal scene recognition process with reference to fig. 11, 12, and 13.

Firstly, after a signal scene classification program starts, the acquisition frequency is cleared to 0;

next, an i-th sensing value Data [ i ] is acquired, wherein i is calculated from 0;

next, calculating the variation of the i-th sensing value Data [ i ] and the i-1-th sensing value Data [ i-1], and sensing the variation sigma [ i ] =data [ i ] -Data [ i-1];

then, the i-th sensing variation is added to the i-1-th sensing variation, and σ=σ [ i ] +σ [ i-1], with the initial value of σ being 0; judging whether N times of data acquisition is completed or not, if not, continuing to acquire, if so, calculating a change rate, wherein the change rate is alpha=sigma/times, and because the acquired data interval is fixed, the acquired times reflect the acquisition time, and the accumulated value of sigma reflects the change intensity in the period;

If the change rate is the forward change rate, continuing to judge the change strength and duration:

the change intensity of the sensing line is smaller than that of the upper noise line, and the sensing line is a second signal scene when the duration time is the second signal scene time T2;

the change intensity of the sensing line is larger than the upper noise line and smaller than the maximum signal line, and the duration time is the fourth signal scene time T4, and the fourth signal scene is the fourth signal scene;

the change intensity of the sensing line is larger than that of the maximum signal line, and the duration is the fifth signal scene time T5, and the fifth signal scene is the fifth signal scene;

if the change rate is negative change rate, continuing to judge the change strength and duration:

the change intensity of the sensing line is smaller than that of the noise line, the duration time is the first signal scene time T1, and the sensing line is the first signal scene;

the variation intensity of the sensing line shakes up and down in the range of the upper noise line and the lower noise line, and then the sensing line is a third signal scene;

the change intensity of the sensing line is larger than that of the lower noise line and smaller than that of the touch line, and the duration time is the sixth signal scene time T6, and the sixth signal scene is the sixth signal scene;

the change intensity of the sensing line is larger than that of the touch line and smaller than that of the minimum signal line, and the duration is the seventh signal scene time T7, and then the seventh signal scene (touch scene) is obtained;

The change intensity of the sensing line is larger than that of the minimum signal line, and the duration time is the eighth signal scene time T8, and then the eighth signal scene is the eighth signal scene;

if the change rate is 0, the sensing line is not changed, and the sensing line is a special scene of the third signal scene and belongs to the third signal scene.

Storing the current signal scene by using a signal scene memory, wherein the signal memory can be RAM or FLASH; comparing the current signal scene with the last signal scene using a signal scene comparator, which conventionally may be implemented using a program, such as subtracting the previously stored signal scene from the latest signal scene;

according to the scene comparison result, using an intra-scene processor to perform signal processing of the same scene, or using an inter-scene processor to perform switching of different scenes of signals and signal processing; if the signal processing of the same scene is performed, the signal processing mode of the current scene is maintained, and if the signal processing of the scenes is performed, the signal processing mode of the latest scene is started. The general processing mode is as follows:

first signal scenario: reference line = reference line-first signal scene constant, typically, the first signal scene constant may take between 0.2 and 0.5 times the difference between the noise line and the reference line;

Second signal scenario: reference line = reference line + second signal scene constant, typically, the first signal scene constant may take between 0.3 and 0.6 times the difference between the noise line and the reference line;

third signal scenario: reference line = reference line;

fourth signal scenario: reference line = reference line + fourth signal scene constant, typically, the fourth signal scene constant may be between 0.2 and 0.5 times the difference between the sense line and the reference line;

fifth signal scenario: reference line = reference line + fifth signal scene constant, typically, the fifth signal scene constant may be between 0.6 and 0.8 times the difference between the sense line and the reference line;

sixth signal scenario: reference line = reference line-sixth signal scene constant, typically, the sixth signal scene constant may be between 0.6 and 0.8 times the difference between the sense line and the reference line;

seventh signal scenario: reference line = reference line, considered touch-generated, without adjusting the reference line;

eighth signal scenario: reference line = sense line;

the key information is processed by using a key information decider, and key detection generally comprises the steps of carrying out key time statistics on the time data of key pressing, carrying out key debouncing processing on the key data, and finally generating the key data, wherein the key data can be used as input of a user application system. The key detection is generally performed by comparing a sampling sensing line with a touch line, if the sampling sensing line exceeds the touch line, the touch is considered to be generated at the time, and the key debouncing operation is performed by taking the instability of human body touch and signals into consideration through the key duration (the number of times of continuously detecting the touch generation in a certain time is commonly adopted).

The cooperative work effects of the touch detection unit, the touch detection controller, the signal preprocessor, the signal scene classifier, the signal scene memory, the signal scene comparator, the signal scene processor and the key information determiner are shown in the signal scene switching schematic diagram of fig. 14:

when the change rate and the change intensity of the sensing line exceed the touch line and are smaller than the minimum signal line, and the duration time T1001 meets the requirement (exceeds the seventh signal scene time T7), the sensing line is regarded as being touched, and the sensing line is regarded as a seventh signal scene;

next, when the change rate and the change strength of the sensing line exceed the minimum signal line and the duration time T1002 meets the requirement (exceeds the eighth signal scene time T8), the sensing line is regarded as being switched into the eighth signal scene, the signals are processed according to the eighth signal scene, and the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line are correspondingly adjusted, so that the self-adaptive 'water-rise ship height' is realized;

next, when the change rate and the change strength of the sensing line exceed the upper noise line and are smaller than the maximum signal line, and when the duration time T1003 meets the requirement (exceeds the fourth signal scene time T4), the sensing line is regarded as being switched into a fourth signal scene, signals are processed according to the fourth signal scene, and the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line are correspondingly adjusted, so that the self-adaptive 'water-rise ship height' is realized, and if the sensing line is kept in the fourth scene, the sensing line is continuously adjusted within the duration time T1004, as shown by the ladder shape in the figure;

Next, when the change rate and the change intensity of the sensing line exceed the touch line and are smaller than the minimum signal line, and when the duration meets the requirement (exceeds the seventh signal scene time T7), the sensing line is regarded as touch generation, and then the sensing line is a seventh signal scene;

next, when the duration T1005 meets the requirement (exceeds the first signal scene time T1), switching to the first signal scene, processing the signals according to the first signal scene, and correspondingly adjusting the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line, thereby realizing self-adaptive "water-rise ship height", and if the sensing line is kept in the first scene, continuing to adjust gradually within the duration T1006, as shown by the ladder shape in the figure;

next, when the duration time T1007 meets the requirement (exceeds the second signal scene time T2), switching to the second signal scene, processing the signal according to the second signal scene, and correspondingly adjusting the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line, thereby realizing the self-adaptive "water-rise ship height";

Next, when the change rate and the change strength of the sensing line exceed the lower noise line and are smaller than the touch line, and the duration time T1008 meets the requirement (exceeds the sixth signal scene time T6), the sensing line is regarded as being switched into a sixth signal scene, signals are processed according to the sixth signal scene, and the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line are correspondingly adjusted, so that the self-adaptive 'water-rise ship height' is realized;

next, when the change rate and the change strength of the sensing line exceed the maximum signal line and the duration time T1009 meets the requirement (exceeds the time T5 of the fifth signal scene), the sensing line is regarded as being switched into the fifth signal scene, the signals are processed according to the fifth signal scene, and the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line are correspondingly adjusted, so that the self-adaptive 'water-rise ship height' is realized;

next, when the duration T1010 meets the requirement (exceeds the sixth signal scene time T6), the sensing line is regarded as being switched into the sixth signal scene, the signals are processed according to the sixth signal scene, and the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line are correspondingly adjusted, so that the self-adaptive "water-rise ship height" is realized, and if the sensing line is kept in the sixth scene, the sensing line is continuously adjusted gradually within the duration T1011, as shown by the ladder shape in the figure;

Then, the sensing line change rate and the change intensity are dithered in the upper noise line and the lower noise line, when the duration meets the requirement (exceeds the third signal scene time T3), the sensing line is regarded as being switched into the third signal scene, the signals are processed according to the third signal scene, and the maximum signal line, the upper noise line, the lower noise line, the reference line, the touch line and the minimum signal line do not need to be adjusted.

In another embodiment, the invention also discloses an electronic device, which comprises: the touch detection device comprises one or more touch switches, a touch detection unit, a signal scene classification unit, a signal scene storage unit, a scene comparison unit, an in-scene processing unit, an inter-scene processing unit and a key information judging unit; the touch detection unit is used for acquiring touch key signals to obtain a current signal sensing value, wherein the sensing value is the number of pulses in a certain time;

the signal scene storage unit is used for storing the current signal scene;

It should be noted that, as will be understood by those skilled in the art, all or part of the steps for implementing the above-described method embodiments may be implemented by hardware related to program instructions, the above-described program may be stored in a computer readable storage medium, and the program when executed, performs steps including the above-described method embodiments, where the above-described storage medium includes: various media capable of storing program code, such as ROM, RAM, magnetic disk, or optical disk.

Finally, it should be noted that the foregoing description is only a preferred embodiment of the present invention, and is only for illustrating the technical solution of the present invention, but is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A scene type signal self-adaptive processing method of a capacitive touch key is characterized by comprising the following steps:

acquiring touch key signals to obtain a current signal sensing value, wherein the sensing value is the number of pulses in a certain time;

classifying the signal scenes according to the change rate, the change strength and the change duration of the sensing value, and determining the current signal scene;

storing a current signal scene;

comparing the current signal scene with the last signal scene to determine whether the scene changes;

if the signal scene is unchanged, using a signal processing mode of the same scene;

if the signal scene is changed, switching the scene, and using a signal processing mode of the new scene;

performing key signal processing according to the signal processing mode;

the classifying of the signal scene according to the change rate, the change intensity and the change duration of the sensing value comprises at least one of the following scenes:

the reference line is determined by a sensing value when the key is not touched under ideal conditions;

the signal processing method using the new scene comprises the following steps of adjusting a reference line:

When the current scene is determined to be a first signal scene, the reference line = reference line-first signal scene constant, the first signal scene constant taking down between 0.2 and 0.5 times the difference between the noise line and the reference line;

when the current scene is determined to be a seventh signal scene, touch is generated, and a reference line is not adjusted;

When the current scene is determined to be an eighth signal scene, the reference line = sensing line, the sensing line being determined by a sensing value;

after the reference line is redetermined, the minimum signal line, the lower noise line, the touch line, the upper noise line and the maximum signal line are redetermined according to the difference value or the proportion of the original minimum signal line, the original lower noise line, the original touch line, the original upper noise line and the original maximum signal line and the original reference line;

the key signal processing according to the signal processing mode specifically comprises the following steps: the key is pressed when the sensed value is greater than the touch line for a certain time, otherwise the key is not pressed.

2. The method for adaptively processing a scene-type signal of a capacitive touch key according to claim 1, wherein the acquisition of the touch key signal uses a relaxation oscillation frequency measurement method or a charge transfer measurement method to detect the touch signal.

3. The method for adaptively processing a scene-type signal of a capacitive touch key according to claim 1, wherein after the touch key signal is acquired, the signal is preprocessed, wherein the preprocessing is specifically two-stage processing, the first-stage processing is sliding window dynamic tracking filtering, and the second-stage processing is inertial filtering.

4. The method for adaptively processing a scene signal of a capacitive touch key according to claim 3, wherein the sliding window dynamic tracking filtering is specifically: n sensing values obtained continuously are regarded as a queue, the length of the queue is fixed to be N, and N data in the queue is subjected to arithmetic average operation by adopting a first-in first-out principle, so that a new filtering result is obtained.

5. The method for adaptively processing a scene signal of a capacitive touch key according to claim 3, wherein the inertial filtering is specifically: the following formula was used for filtering

Current filtering result= (1-a) current signal value + a last filtering result;

wherein, the value range of a is between 0 and 1.

6. The method for adaptively processing a scene-type signal of a capacitive touch key according to claim 1, wherein the rate of change, the intensity of change and the duration of change are specifically as follows: continuously collecting sensing values, recording the ith sensing value as Data [ i ], measuring the sensing variable sigma [ i ] =data [ i ] -Data [ i-1] for the ith time, and accumulating the sensing variable sigma [ i ] to sigma, wherein sigma is initialized to 0; until i reaches a preset maximum acquisition time, or the absolute value of sigma i is smaller than a preset first threshold; the rate of change is sigma/N, the intensity of change is the absolute value of sigma, and the time of change is i times the single acquisition time.

7. A storage medium storing a computer program implementing the method of any one of claims 1-6.

8. An electronic device, comprising: the touch detection device comprises one or more touch switches, a touch detection unit, a signal scene classification unit, a signal scene storage unit, a scene comparison unit, an in-scene processing unit, an inter-scene processing unit and a key information judging unit; wherein, the liquid crystal display device comprises a liquid crystal display device,

the signal scene storage unit is used for storing the current signal scene;

The key information judging unit is used for carrying out key signal processing according to the signal processing mode;