阅读说明：本技术 电容式触控板上的液体检测方法及其控制器 (Liquid detection method on capacitive touch pad and controller thereof ) 是由 杨东敏 杨学伟 包天雯 于 2018-11-19 设计创作，主要内容包括：本发明公开一种电容式触控板上的液体检测方法及其控制器,该液体检测方法先取得该电容式触控板每一个第一感应电极的感应量作为一第一感应信息,再取得该电容式触控板的各感应点的感应量,再将每一个第一感应电极上的所有感应点的感应量予以累加后作为一第二感应信息,接着根据该第一感应信息与该第二感应信息,决定一差异信息；该差异信息被用来判断是否有液体存在于该电容式触控板上。(The invention discloses a liquid detection method on a capacitive touch pad and a controller thereof, wherein the liquid detection method firstly obtains the induction quantity of each first induction electrode of the capacitive touch pad as first induction information, then obtains the induction quantity of each induction point of the capacitive touch pad, then accumulates the induction quantities of all the induction points on each first induction electrode as second induction information, and then determines difference information according to the first induction information and the second induction information; the difference information is used to determine whether liquid is present on the capacitive touchpad.)

1. A liquid detection method on a capacitive touch pad comprises a plurality of first induction electrodes and a plurality of second induction electrodes, wherein the intersection of the first induction electrodes and the second induction electrodes forms a plurality of induction points; the liquid detection method is characterized by comprising the following steps:

(a) Measuring self-capacitance of the plurality of first sensing electrodes to obtain first sensing information, wherein the first sensing information comprises the sensing quantity of each first sensing electrode;

(b) Measuring mutual capacitance of the plurality of induction points to obtain induction quantity of each induction point;

(c) Respectively calculating the sum of the induction quantities of the induction points on each first induction electrode to obtain second induction information; and

(d) and judging whether liquid exists on the capacitive touch pad or not according to the first induction information and the second induction information.

2. The method of claim 1, wherein the self-capacitance measurement of step (a) comprises simultaneously driving a plurality of the first sensing electrodes.

3. The liquid detecting method according to claim 1, wherein the step (d) includes:

(d1) According to the first induction information, performing normalization operation on the second induction information to obtain third induction information;

(d2) Subtracting the third sensing information from the first sensing information to obtain a plurality of first difference values;

(d3) Comparing the first difference values with a critical value respectively, and judging the number of the difference values larger than the critical value; and

(d4) Determining whether a liquid exists on the capacitive touch pad according to the quantity obtained in the step (d 3).

4. The method according to claim 3, wherein the normalization operation in the step (d1) multiplies all values of the second sensing information by a ratio; the denominator of the ratio is the maximum value in the second sensing information, and the numerator of the ratio is the sensing quantity of the first sensing electrode corresponding to the maximum value.

5. The method of claim 1, wherein the measuring of the mutual capacitance of step (b) comprises sensing each of the sensing points for a second period, the second period having a length less than or equal to 0.28125 us.

6. The method of claim 5, wherein the self-contained measurement of step (a) includes sensing each of the first sensing electrodes for a first period, and the length of the second period is less than or equal to the length of the first period.

7. the method of claim 1, wherein the measuring of the mutual capacitance of step (b) comprises driving each of the sensing points with a second driving signal having a second frequency, the second frequency being greater than or equal to 1 MHz.

8. The method of claim 7, wherein the self-contained measurement of step (a) comprises driving each of the first sensing electrodes with a first driving signal having a first frequency, the second frequency being greater than or equal to the first frequency.

9. The method as claimed in claim 7, wherein after the step (d) determines that the liquid is present on the capacitive touch pad, the controller drives each sensing point with a driving signal greater than or equal to the second frequency to perform the mutual capacitance measurement, so as to obtain a position of a contact object.

10. a controller is used for detecting whether liquid exists on a touch pad or not, wherein the touch pad comprises a plurality of first sensing electrodes and a plurality of second sensing electrodes, and a plurality of sensing points are formed by the intersection of the first sensing electrodes and the second sensing electrodes; characterized in that, the controller comprises:

a storage medium for storing a firmware program;

A processor coupled to the storage medium, the processor executing the firmware program to perform the following steps:

(a) Measuring self-capacitance of the plurality of first sensing electrodes to obtain first sensing information, wherein the first sensing information comprises the sensing quantity of each first sensing electrode;

(b) Measuring mutual capacitance of the plurality of induction points to obtain induction quantity of each induction point;

(c) respectively calculating the sum of the induction quantities of the induction points on each first induction electrode to obtain second induction information; and

(d) And judging whether liquid exists on the capacitive touch pad or not according to the first induction information and the second induction information.

11. The controller of claim 10, wherein the self-capacitance measurement of step (a) comprises driving a plurality of the first sensing electrodes simultaneously.

12. The controller of claim 10, wherein said step (d) comprises:

(d1) According to the first induction information, performing normalization operation on the second induction information to obtain third induction information;

(d2) Subtracting the third sensing information from the first sensing information to obtain a plurality of difference values;

(d3) comparing the difference values with a critical value respectively, and judging the number of the difference values larger than the critical value; and

(d4) Determining whether a liquid exists on the capacitive touch pad according to the quantity obtained in the step (d 3).

13. the controller according to claim 12, wherein the normalization operation in the step (d1) multiplies all values of the second sensed information by a ratio; the denominator of the ratio is the maximum value in the second sensing information, and the numerator of the ratio is the sensing quantity of the first sensing electrode corresponding to the maximum value.

14. The controller of claim 10, wherein the mutual capacitance measurement of step (b) comprises sensing each sensing point for a second period, the second period having a length less than or equal to 0.28125 us.

15. the controller of claim 14, wherein the self-contained measurement of step (a) comprises sensing each of the first sensing electrodes for a first period, and the length of the second period is less than or equal to the length of the first period.

16. The controller of claim 14, wherein the mutual capacitance measurement of step (b) comprises driving each of the sensing points with a second driving signal having a second frequency, the second frequency being greater than or equal to 1 MHz.

17. The controller of claim 16, wherein the self-contained measurement of step (a) comprises driving each of the first sensing electrodes with a first driving signal having a first frequency, the second frequency being greater than or equal to the first frequency.

18. The controller according to claim 16, wherein after determining that liquid is present on the capacitive touch pad in step (d), the controller drives each sensing point with a driving signal higher than or equal to the second frequency to perform the mutual capacitance measurement to obtain a position of a contact object.

19. A liquid detection method on a capacitive touch pad comprises a plurality of first induction electrodes in an X direction, a plurality of second induction electrodes in a Y direction, and a plurality of induction points formed by the intersection of the first induction electrodes and the second induction electrodes; the liquid detection method is characterized by comprising the following steps:

(a) measuring self-capacitance of the first induction electrodes and the second induction electrodes to obtain first X-axis induction information and first Y-axis induction information, wherein the first X-axis induction information comprises induction quantity of each first induction electrode, and the first Y-axis induction information comprises induction quantity of each second induction electrode;

(b) Measuring mutual capacitance of the plurality of induction points to obtain induction quantity of each induction point;

(c) respectively calculating the sum of the induction quantities of the plurality of induction points on each first induction electrode to obtain second X-axis induction information, and respectively calculating the sum of the induction quantities of the plurality of induction points on each second induction electrode to obtain second Y-axis induction information; and

(d) And judging whether liquid exists on the capacitive touch pad or not according to the first X-axis induction information, the first Y-axis induction information, the second X-axis induction information and the second Y-axis induction information.

20. The method of claim 19, wherein in step (a), the measuring the self-capacitance of the first sensing electrodes comprises driving a plurality of the first sensing electrodes simultaneously, and the measuring the self-capacitance of the second sensing electrodes comprises driving a plurality of the second sensing electrodes simultaneously.

21. The liquid detecting method according to claim 19, wherein the step (d) includes:

(d1) Normalizing the second X-axis induction information according to the first X-axis induction information to obtain third X-axis induction information, and normalizing the second Y-axis induction information according to the first Y-axis induction information to obtain third Y-axis induction information;

(d2) Subtracting the third X-axis sensing information from the first X-axis sensing information to obtain a plurality of first X-axis difference values, and subtracting the third Y-axis sensing information from the first Y-axis sensing information to obtain a plurality of first Y-axis difference values;

(d3) Comparing the plurality of first X-axis difference values and the plurality of first Y-axis difference values with a critical value respectively, and judging the number of the first X-axis difference values and the second Y-axis difference values which are larger than the critical value; and

(d4) Determining whether a liquid exists on the capacitive touch pad according to the quantity obtained in the step (d 3).

22. the liquid detection method according to claim 21, wherein in the step (d 1):

Normalizing the second X-axis induction information to multiply all values of the second X-axis induction information by a first ratio, wherein the denominator of the first ratio is the maximum value in the second X-axis induction information, and the numerator of the first ratio is the induction quantity of the first induction electrode corresponding to the maximum value in the second X-axis induction information; and

And performing normalization operation on the second Y-axis induction information to multiply all values of the second Y-axis induction information by a second ratio, wherein the denominator of the second ratio is the maximum value in the second Y-axis induction information, and the numerator of the second ratio is the induction quantity of the second induction electrode corresponding to the maximum value in the second Y-axis induction information.

23. the method of claim 19, wherein the measuring of the mutual capacitance of step (b) comprises sensing each of the sensing points for a second period, the second period having a length less than or equal to 0.28125 us.

24. The method of claim 23, wherein the self-contained measurement of step (a) includes sensing each of the first sensing electrodes and each of the second sensing electrodes for a first period, and the length of the second period is less than or equal to the length of the first period.

25. The method of claim 19, wherein the measuring of the mutual capacitance of step (b) comprises driving each of the sensing points with a second driving signal having a second frequency, the second frequency being greater than or equal to 1 MHz.

26. the method of claim 25, wherein the self-contained measurement of step (a) comprises driving each of the first sensing electrodes and each of the second sensing electrodes with a first driving signal having a first frequency, the second frequency being greater than or equal to the first frequency.

27. The method as claimed in claim 25, wherein after determining that liquid is present on the capacitive touch pad in the step (d), the controller drives each sensing point with a driving signal greater than or equal to the second frequency to perform the mutual capacitance measurement, so as to obtain a position of a contact object.

Technical Field

The present disclosure relates to a method for detecting an object on a capacitive touch pad, and more particularly, to a method for detecting a liquid on a capacitive touch pad.

Background

the capacitive touch pad determines touch information of an object, such as the type of the object, according to the change of the capacitance. When a liquid (e.g., water) is present on the capacitive touchpad and a user's finger is in contact with the liquid, the conventional capacitive touchpad controller cannot recognize that the liquid is present on the capacitive touchpad.

Disclosure of Invention

The present invention provides a liquid detection method on a capacitive touch panel and a controller thereof.

according to an embodiment of the present invention, a method for detecting a liquid on a capacitive touch panel includes the following steps (a) to (d); the capacitive touch panel comprises a plurality of first sensing electrodes and a plurality of second sensing electrodes, wherein a plurality of sensing points are formed by the intersection of the first sensing electrodes and the second sensing electrodes;

(a) Measuring self-capacitance of the plurality of first sensing electrodes to obtain first sensing information, wherein the first sensing information comprises the sensing quantity of each first sensing electrode;

(b) Measuring mutual capacitance of the plurality of induction points to obtain induction quantity of each induction point;

(c) respectively calculating the sum of the induction quantities of the induction points on each first induction electrode to obtain second induction information; and

(d) And judging whether liquid exists on the capacitive touch pad or not according to the first induction information and the second induction information.

according to an embodiment of the present invention, a controller of a capacitive touch panel is configured to detect whether a liquid is present on the touch panel, the touch panel includes a plurality of first sensing electrodes and a plurality of second sensing electrodes, and intersections of the plurality of first sensing electrodes and the plurality of second sensing electrodes form a plurality of sensing points; the controller includes: a storage medium and a processor; wherein the storage medium is used for storing a firmware program, the processor is coupled to the storage medium, and the processor executes the aforementioned steps (a) to (d) by executing the firmware program.

According to another embodiment of the present invention, a method for detecting a liquid on a capacitive touchpad comprises the following steps (a) to (d); the capacitive touch panel comprises a plurality of first sensing electrodes in the X direction and a plurality of second sensing electrodes in the Y direction, and a plurality of sensing points are formed by the intersection of the first sensing electrodes and the second sensing electrodes;

(a) Measuring self-capacitance of the first induction electrodes and the second induction electrodes to obtain first X-axis induction information and first Y-axis induction information, wherein the first X-axis induction information comprises induction quantity of each first induction electrode, and the first Y-axis induction information comprises induction quantity of each second induction electrode;

(b) measuring mutual capacitance of the plurality of induction points to obtain induction quantity of each induction point;

(c) respectively calculating the sum of the induction quantities of the plurality of induction points on each first induction electrode to obtain second X-axis induction information, and respectively calculating the sum of the induction quantities of the plurality of induction points on each second induction electrode to obtain second Y-axis induction information; and

(d) And judging whether liquid exists on the capacitive touch pad or not according to the first X-axis induction information, the first Y-axis induction information, the second X-axis induction information and the second Y-axis induction information.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

FIG. 1 is a schematic diagram of a capacitive touch device according to the present invention;

FIG. 2A is a flow chart of a liquid detection method of a capacitive touchpad according to the present invention;

FIG. 2B illustrates one embodiment of step S40 of FIG. 2A;

fig. 3 provides first X-axis sensing information and first Y-axis sensing information of the capacitive touchpad;

FIG. 4A provides the sensing quantities of a plurality of sensing points of the capacitive touchpad;

Fig. 4B is a schematic diagram of second X-axis sensing information and second Y-axis sensing information of the capacitive touch panel;

Fig. 4C is a schematic diagram of third X-axis sensing information and third Y-axis sensing information of the capacitive touch panel;

FIG. 4D is a schematic diagram of X-axis difference information and Y-axis difference information of the capacitive touch pad;

FIG. 5 illustrates the components of the controller of FIG. 1;

FIG. 6 provides one embodiment of the sensing unit of FIG. 5;

Fig. 7A to 7D are signal waveform diagrams illustrating driving signals and sensing time used by a controller in performing self-capacitance measurement and mutual capacitance measurement according to the present invention.

wherein the reference numerals

1 capacitive touch device 10 capacitive touch pad

100 sense point 20 controller

21 drive unit 22 sensing unit

221 sense circuit 222 sample-and-hold circuit

23 processor 231 storage medium

30 liquid

Detailed Description

The invention will be described in detail with reference to the following drawings, which are provided for illustration purposes and the like:

Referring to fig. 1, a capacitive touch device 1 includes a capacitive touch pad 10 and a controller 20. The capacitive touchpad 10 may be transparent or opaque. The capacitive touch panel 10 includes a plurality of sensing electrodes X1-Xn in the X direction, a plurality of sensing electrodes Y1-Ym in the Y direction, and a plurality of sensing points 100 are formed by intersections of the sensing electrodes X1-Xn and the sensing electrodes Y1-Ym. The positions of the sensing electrodes X1 Xn and Y1 Ym in FIG. 1 are only schematic and not intended to limit the present invention. The controller 20 is coupled to the capacitive touch panel 10 for detecting the sensing quantities of the plurality of sensing electrodes X1-Xn, the plurality of sensing electrodes Y1-Ym, and the plurality of sensing points 100. Reference numeral 30 represents a liquid (e.g., water) present on the capacitive touchpad 10. A conductor, such as a finger F, contacts the liquid 30, such that the liquid 30 is grounded.

For convenience of illustration, in the examples provided in fig. 3 and 4A to 4D, the capacitive touch panel 10 includes 7 first sensing electrodes X1 to X7 in the X direction and 12 second sensing electrodes Y1 to Y12 in the Y direction. The intersections of the first sensing electrodes X1-X7 and the second sensing electrodes Y1-Y12 form 84 sensing points 100.

Referring to fig. 2A, a flow chart of a liquid detection method of the capacitive touchpad 10 according to the present invention is shown, the liquid detection method includes the following steps S10-S40.

in step S10, the controller 20 measures Self-capacitance of the first sensing electrodes X1 to X7 in the X direction and the second sensing electrodes Y1 to Y12 in the Y direction (Self-capacitance measurement), so as to obtain first X-axis sensing information dV _ Self _ X and first Y-axis sensing information dV _ Self _ Y shown in fig. 3. The first X-axis sensing information dV _ Self _ X includes the sensing quantities of the first sensing electrodes X1 through X7. As shown in fig. 3, the sensing amount of the first sensing electrode X1 is 8, and the sensing amount of the second sensing electrode X7 is 22. The first Y-axis sensing information dV _ Self _ Y includes the sensing quantities of the second sensing electrodes Y1 through Y12. As shown in fig. 3, the sensing amount of the second sensing electrode Y1 is 0, and the sensing amount of the second sensing electrode Y12 is 4.

the self-capacitance measurement includes driving a plurality of sensing electrodes simultaneously. In one embodiment, when one of the first sensing electrodes or the second sensing electrode is driven and read, the driving signals having the same phase are also simultaneously output to the adjacent first or second sensing electrodes of the driven first or second sensing electrode. For example, when sensing the sensing amount of the first sensing electrode X3, the controller 20 simultaneously outputs a driving signal to the first sensing electrode X3 and two first sensing electrodes X2 and X4 adjacent to the first sensing electrode X3. When the sensing amount of the second sensing electrode Y3 is measured, the controller 20 simultaneously transmits the driving signal to the second sensing electrode Y3 and two second sensing electrodes Y2 and Y4 adjacent to the second sensing electrode Y3. In another embodiment, the self-capacitance measurement outputs driving signals of the same phase to all the first sensing electrodes X1-X7 at the same time, and receives the signals of the first sensing electrodes X1-X7 together, and outputs driving signals of the same phase to all the second sensing electrodes Y1-X12 together, and receives the signals of the second sensing electrodes Y1-Y12 together.

in step S20, the controller 20 performs mutual-capacitance measurement (mutual-capacitance measurement) on the sensing points 100 to obtain the sensing quantities of the sensing points 100 as shown in fig. 4A. In fig. 4A, the sensing amount of the sensing point 100 formed by the first sensing electrode X1 and the second sensing electrode Y1 is 3, and the sensing amount of the sensing point 100 formed by the first sensing electrode X3 and the second sensing electrode Y7 is 178. The details of the mutual capacitance measurement are well known to those skilled in the art of touch control, and are not described in detail herein.

The order of step S10 and step S20 may be interchanged. In one embodiment, step S20 is performed first, and step S10 is performed again.

After obtaining the sensing quantities of the sensing points 100, step S30 is performed to respectively calculate the sum of the sensing quantities of the sensing points 100 on each of the first sensing electrodes X1 to X7 to obtain second X-axis sensing information dVsum _ Mutual _ X, and to respectively calculate the sum of the sensing quantities of the sensing points 100 on each of the second sensing electrodes Y1 to Y12 to obtain second Y-axis sensing information dVsum _ Mutual _ Y. Fig. 4b shows the second X-axis sensing information dVsum _ Mutual _ X and the second Y-axis sensing information dVsum _ Mutual _ Y. Each of the first sensing electrodes X1-X7 and each of the second sensing electrodes Y1-Y12 corresponds to an accumulated sensing quantity. For example, in fig. 4B, the first sensing electrode X1 includes 12 sensing points 100, and the sum of the sensing quantities of the 12 sensing points 100 is 103. The second sensing electrode Y1 includes 7 sensing points 100, and the sum of the sensing amounts of the 7 sensing points 100 is 24.

Step S40 determines whether liquid exists on the capacitive touch panel 10 according to the first X-axis sensing information dV _ Self _ X, the second X-axis sensing information dVsum _ Mutual _ X, the first Y-axis sensing information dV _ Self _ Y, and the second Y-axis sensing information dVsum _ Mutual _ Y.

one embodiment of step S40 includes determining an X-axis difference information dV _ diff _ X according to the first X-axis sensing information dV _ Self _ X and the second X-axis sensing information dVsum _ major _ X, determining a Y-axis difference information dV _ diff _ Y according to the first Y-axis sensing information dV _ Self _ Y and the second Y-axis sensing information dVsum _ major _ Y, and determining whether a liquid is present on the capacitive touch panel 10 according to the X-axis difference information dV _ diff _ X and/or the Y-axis difference information dV _ diff _ Y. The more detailed steps are shown in fig. 2B.

In step S401, the second X-axis sensing information dVsum _ status _ X is Normalized according to the first X-axis sensing information dV _ Self _ X to obtain a third X-axis sensing information Normalized _ dVsum _ status _ X, and in an embodiment, the third X-axis sensing information Normalized _ vsum _ status _ X is obtained by normalizing the second X-axis sensing information dVsum _ status _ X according to the sensing quantity "46" of the first sensing electrode X3 corresponding to the maximum value "466" of the second X-axis sensing information dVsum _ status _ X, as shown in fig. 4C. The normalization operation is to multiply all values of the second X-axis sensing information dVsum _ Mutual _ X by a ratio 46/466, wherein the denominator "466" is the maximum value of the second X-axis sensing information dVsum _ Mutual _ X, and the numerator "46" is the sensing quantity of the first sensing electrode X3 corresponding to the first sensing electrode X3.

in step S402, the second Y-axis sensing information dVsum _ Mutual _ Y is Normalized according to the first Y-axis sensing information dV _ Self _ Y to obtain a third Y-axis sensing information Normalized _ dVsum _ Mutual _ Y. In one embodiment, the second Y-axis sensing information dVsum _ Mutual _ Y is Normalized according to the sensing amount "209" of the second sensing electrode Y8 corresponding to the maximum value "564" of the second Y-axis sensing information dVsum _ Mutual _ Y, so as to obtain the third Y-axis sensing information Normalized _ dVsum _ Mutual _ Y shown in fig. 4C. The normalization operation is to multiply all values of the second Y-axis sensing information dVsum _ Mutual _ Y by a ratio 209/564, wherein the denominator "564" is the maximum value of the second Y-axis sensing information dVsum _ Mutual _ Y, and the numerator "209" is the sensing amount of the second sensing electrode Y8 corresponding to the second sensing electrode Y8.

in step S403, the first X-axis sensing information dV _ Self _ X is subtracted by the third X-axis sensing information Normalized _ dVsum _ major _ X to obtain an X-axis difference information including a plurality of X-axis differences. The plurality of X-axis difference values are shown as X-axis difference information dV _ diff _ X of fig. 4D. For example, in the first X-axis sensing information dV _ Self _ X, the sensing amount of the first sensing electrode X3 is 46, and in the third X-axis sensing information Normalized _ dVsum _ Mutual _ X, the value corresponding to the first sensing electrode X3 is 46. Subtracting 46 from 46 is the X-axis difference 0 corresponding to the first sensing electrode X3 in fig. 4D.

in step S404, the third Y-axis sensing information Normalized _ dVsum _ Mutual _ Y is subtracted from the first Y-axis sensing information dV _ Self _ Y to obtain a Y-axis difference information including a plurality of Y-axis differences. The plurality of Y-axis difference values are shown as difference information dV _ diff _ Y of fig. 4D. For example, in the first Y-axis sensing information dV _ Self _ Y, the sensing amount of the second sensing electrode Y9 is 146, and in the third Y-axis sensing information Normalized _ dVsum _ Mutual _ Y, the value corresponding to the second sensing electrode Y9 is 72. Subtracting 72 from 146 is the Y-axis difference 74 corresponding to the second sensing electrode Y9 in fig. 4C.

In step S405, differences between the X-axis difference information dV _ diff _ X and the Y-axis difference information dV _ diff _ Y are compared with a threshold value to determine the number of differences greater than the threshold value. For example, assuming that the threshold value is 50, comparing a plurality of X-axis difference values in the X-axis difference information dV _ diff _ X with the threshold value 50 may obtain the number of X-axis difference values greater than the threshold value as 2, and comparing a plurality of Y-axis difference values in the Y-axis difference information dV _ diff _ Y with the threshold value 50 may obtain the number of Y-axis difference values greater than the threshold value as 2.

step S406 is to determine whether there is liquid on the capacitive touch pad 10 according to the number of the difference values greater than the threshold value obtained in step S405. One embodiment of step S406 is to determine that liquid exists on the capacitive touch pad 10 when the number of differences greater than the threshold is greater than 0 (no matter in the X direction or the Y direction). According to the comparison result of the step S405, there are four differences greater than the threshold, so that the step S406 determines that liquid exists on the capacitive touch pad 10.

The order of the various steps of the above described embodiments may be changed. As can be understood from the above embodiments, the controller 20 can determine whether there is liquid on the touch pad 10 according to the difference information in a single direction (X or Y). It is therefore feasible to omit certain steps of fig. 2A and 2B. For example, the step of obtaining the first Y-axis sensing information, the second Y-axis sensing information and the Y-axis difference information may be omitted, and the controller 20 may determine that the liquid exists on the touch pad 10 according to the difference value greater than the threshold value 50 in the X-axis difference information being 2.

From the above description, it can be understood that the present invention provides a liquid detection method on a capacitive touch panel, where the capacitive touch panel includes a plurality of first sensing electrodes and a plurality of second sensing electrodes, and intersections of the plurality of first sensing electrodes and the plurality of second sensing electrodes form a plurality of sensing points; the liquid detection method comprises the following steps:

(a) Measuring self-capacitance of the plurality of first sensing electrodes to obtain first sensing information, wherein the first sensing information comprises the sensing quantity of each first sensing electrode;

(b) Measuring mutual capacitance of the plurality of induction points to obtain induction quantity of each induction point;

(c) Respectively calculating the sum of the induction quantities of the induction points on each first induction electrode to obtain second induction information; and

(d) And judging whether liquid exists on the capacitive touch pad or not according to the first induction information and the second induction information.

Fig. 5 shows one embodiment of the controller 20. The controller 20 includes a driving unit 21, a sensing unit 22, a processor 23 and a storage medium 231. The processor 23 is coupled to the storage medium 231, the driving unit 21 and the sensing unit 22. The processor 23 executes the firmware program stored in the storage medium 231 to control the operations of the driving unit 21 and the sensing unit 22, and generate touch information such as object positions, number, and the like according to the output of the sensing unit 22. In one embodiment, the controller 20 is configured to perform self-capacitance measurement (self-capacitance measurement) on the first sensing electrodes X1-Xn and the second sensing electrodes Y1-Ym, and perform mutual-capacitance measurement (mutual-capacitance measurement) on the sensing points 100. In one embodiment of the self-capacitance measurement, the driving unit 21 provides driving signals to the first sensing electrodes X1-Xn and the second sensing electrodes Y1-Ym, and the sensing unit 22 senses the first sensing electrodes X1-Xn and the second sensing electrodes Y1-Ym to obtain the sensing quantities of the first and second sensing electrodes. One embodiment of the mutual capacitance measurement is to provide a driving signal to the first sensing electrodes X1 Xn in the X direction by the driving unit 210 and to sense the second sensing electrodes Y1 Ym in the Y direction by the sensing unit 22 to obtain the sensing quantities of the sensing points 100. The processor 21 implements the liquid detection method by executing the firmware program stored in the storage medium 231.

in one embodiment, the sensing unit 22 includes at least one sensing circuit 221 and at least one Sample and Hold (Sample and Hold) circuit 222. One embodiment of the sensing circuit 221 and the sample-and-hold circuit 222 is shown in FIG. 6. the sensing circuit 221 includes a sensing capacitor C₁a switch SW1 and an operational amplifier OP. Sensing capacitance C₁connected to a first input IN of an operational amplifier OP₁And an output terminal OUT, a switch SW₁And a sensing capacitor C₁And (4) connecting in parallel. The output terminal OUT of the operational amplifier OP is connected to the sample-and-hold circuit 222, and the sample-and-hold circuit 222 includes a switch SW₂and a sampling capacitor C₂Switch SW₂Connected between the output terminal OUT of the operational amplifier OP and the sampling capacitor C₂Between, sampling capacitor C₂One terminal of which is grounded and the other terminal of which is connected to the output O/P of the sample-and-hold circuit 222.

The operation of the sensing circuit 221 is described below, in which the switch SW is switched in the first phase₁Is turned on to sense the capacitor C₁Is 0. In the second stage switch SW₁Open, switch SW₂is turned on, and the first input terminal IN of the operational amplifier OP₁The object to be measured (i.e. the sensing point 100, the first sensing electrode or the second sensing electrode) is connected for sensing. At the switch SW₂When conducting, the output voltage of the operational amplifier OP is applied to the sampling capacitor C₂charging and sampling capacitor C₂Is equal to the output voltage of the operational amplifier OP.

Sampling capacitor C₂Voltage and switch SW₂the length of time RT that is on is relevant. In one embodiment, the time duration RT is determined according to a time period for the output voltage of the operational amplifier OP to reach a stable state. In various embodiments, the time duration RT may be controlled such that the switch SW₂The switching off is performed before the output voltage of the operational amplifier OP reaches a stable level. At the switch SW₂after disconnection, the capacitor C is sampled₂is used to determine a sensing quantity.

Sampling capacitor C₂The voltage is converted into a digital value by an analog-to-digital converter (not shown), and in one embodiment, the digital value is subtracted by a reference value, which is an output value of the analog-to-digital converter when no object is touched, to obtain the sensing amount. The reference values of the sensing points 100 or the first and second sensing electrodes X1 to Xn and Y1 to Ym are not all the same. The reference value is different according to different driving signals.

In one embodiment, the self-capacitance measurement of step S10 uses the first driving signal TX1 shown in FIG. 7A to control the switch SW₂The waveform of the control signal of (2) is shown in fig. 7B. The mutual capacitance measurement of step S20 uses the second driving signal TX2 shown in FIG. 7C to control the switch SW₂the waveform of the control signal of (2) is shown in fig. 7D. The first driving signal TX1 has a first frequency f1, which is 500KHz in fig. 7A for the first frequency f 1. The second driving signal TX2 has a second frequency f2, and in fig. 7C, the second frequency f2 is 2 MHz. Referring to FIG. 7B and FIG. 7D, when the control signal is 1, the switch SW is turned on₂On, when the control signal is 0, the switch SW₂And (5) disconnecting. Switch SW₂the time length of each turn-on is the first period RT1, and the first period RT1 can be understood as the time length for sensing a first (or second) sensing electrode. During this first period RT1, sensing circuit 221 senses the first or second sense electrode. At the switch SW₂After the turn-off, the sample-and-hold circuit 222 obtains an output voltage, which is used to calculate the sensing amount. The driving is performed by the first sensing electrodes X1-Xn and the second sensing electrodes Y1-Ymthe dynamic and sensing procedure can obtain the first X-axis sensing information dV _ Self _ X and the first Y-axis sensing information dV _ Self _ Y. The second period RT2 may be understood as the length of time a sensing point 100 is sensed. During this second period RT2, sensing circuit 221 senses a sensing point 100. At the switch SW₂after the switch-off, the sample-and-hold circuit 222 obtains an output voltage, which is used to calculate the sensing amount of the sensing point 100. By performing the driving and sensing procedure on all the sensing points 100, the sensing quantities of all the sensing points 100 can be obtained.

in other embodiments, the first frequency f1 may be greater than, equal to, or less than the second frequency f 2. The length of the first period RT1 may be greater than, equal to, or less than the length of the second period RT 2. In one embodiment, the second frequency f2 is 1MHz or higher, such as any frequency in the range of 1MHz to 2 MHz. The second period RT2 is equal to or less than 0.28125us, for example, 0.28125us to 0.09375 us. Generally, the higher the frequency of the driving signal, the shorter the corresponding sensing time. When the mutual capacitance is measured, the higher the frequency of the second driving signal TX2 is, or the shorter the length of the second period RT2 is, the smaller the mutual capacitance induction amount caused by the liquid is, so that the difference between the self-capacitance induction amount of a first or second sensing electrode and the sum of the mutual capacitance induction amounts becomes larger.

In other embodiments, after determining that liquid exists on the capacitive touch pad 10, the controller uses the second driving signal TX2 or other higher frequency driving signals to measure the mutual capacitance of the touch pad 10, and calculates the position of a touched object according to the sensing information obtained by the mutual capacitance measurement. After a certain period of time, the above-mentioned liquid detection method is performed to determine whether liquid still exists on the touch pad 10.

As can be understood from the above description, when a finger touches a liquid on a touch pad, the method provided by the present invention can identify the presence of the liquid. Although the present invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.