Touch sensing system and control method thereof

Abstract

A touch sensing system includes a capacitive touch panel, a controller, and a signal source. The capacitive touch panel is used for input by a user. The controller is connected to the capacitive touch panel and is used to scan the capacitive touch panel. The signal source is used to provide a periodic signal coupled to a user, such that the periodic signal is coupled to the capacitive touch panel via the user.

Description

[Technical Field]

[0001] This invention relates to a touch sensing system, and more particularly to a touch sensing system and control method for improving liquid interference. [Previous Technology]

[0002] Capacitive touch panels are commonly used in electronic devices as input devices, allowing users to input text or gestures. If there is liquid on the capacitive touch panel, such as water or salt water, it may cause touch malfunction. [Summary of the Invention]

[0003] One of the objectives of this invention is to provide a touch sensing system and control method that improves liquid interference.

[0004] According to the present invention, a touch sensing system includes a capacitive touch panel, a controller, and a signal source. The capacitive touch panel is used for input by a user and has a plurality of electrodes. The controller is connected to the capacitive touch panel and is used to scan the plurality of electrodes to generate touch information. The signal source is used to provide a periodic signal coupled to a user, such that the periodic signal is coupled to the capacitive touch panel via the user.

[0005] According to the present invention, a touch sensing system includes a capacitive touch panel, a controller, and a signal source. The capacitive touch panel is for input by a user. The controller is connected to the capacitive touch panel and is used to scan the capacitive touch panel to generate touch information. The controller includes a high-voltage terminal and a ground terminal, and the combination of the high-voltage terminal and the low-voltage terminal is used to provide power to the controller. The signal source is used to provide a periodic signal to the high-voltage terminal or the high-voltage terminal and the low-voltage terminal.

[0006] According to the present invention, a control method for a touch sensing system is provided. The touch sensing system includes a capacitive touch panel and a controller. The controller is coupled to the capacitive touch panel and has a high-voltage terminal and a low-voltage terminal. The combination of the high-voltage terminal and the low-voltage terminal is used to provide power to the controller. The control method includes the following steps: A. Providing a periodic signal to the high-voltage terminal of the controller or the high-voltage terminal and the ground terminal; and B. Scanning the capacitive touch panel using the controller to generate touch information.

[0007] The touch sensing system of the present invention utilizes a signal source to provide a high-frequency periodic signal to improve the interference of liquid on the touch sensing system.

Implementation Method

[0009] Figure 1 shows an embodiment of the control method of the touch sensing system of the present invention. Figure 2 shows a first embodiment of the touch sensing system of the present invention, which can be used to implement the method shown in Figure 1. In Figure 2, the touch sensing system 10 includes a capacitive touch panel 11, a controller 12, and a signal source 13. The capacitive touch panel 11 is used for input by a user 14. In one embodiment, the capacitive touch panel 11 includes m electrodes in the X direction and n electrodes in the Y direction. The X direction is perpendicular to the Y direction. The intersection of the m electrodes and the n electrodes forms m*n sensing points. The controller 12 is connected to the capacitive touch panel 11 and is used to scan the capacitive touch panel 11 to generate touch sensing information. The touch sensing information is, for example, the sensing amount of the m*n sensing points. The signal source 13 is used to provide a periodic signal Sp to the user 14, such that the periodic signal Sp is coupled to the capacitive touch panel 11 via the user 14. In one embodiment, the controller 12 can be connected to the signal source 13 via a wired or wireless means. When there is liquid on the surface of the capacitive touch panel 11, the controller activates the signal source 13 to output a periodic signal Sp.

[0010] Figure 3 shows an embodiment of the signal source of Figure 2. In the embodiment of Figure 3, the signal source 13 includes an oscillator 131 and a boost circuit 132. The oscillator 131 is connected to the boost circuit 132. The oscillator 131 is used to generate an oscillation signal So. The boost circuit 132 is used to boost the oscillation signal So to generate a periodic signal Sp.

[0011] The steps in Figure 1 will be explained next, and please refer to the embodiment in Figure 2. In step S10, the controller 12 scans the capacitive touch panel 11 to generate first touch sensing information. The first touch sensing information includes the sensing quantities of multiple electrodes of the capacitive touch panel 11. The scan performed in step S10 includes, but is not limited to, mutual capacitance scanning. For example, the controller 12 sequentially applies driving signals to m electrodes in the X direction of the capacitive touch panel 11 and senses n electrodes in the Y direction to obtain m*n sensing quantities. Next, step S11 is performed to determine whether there is liquid on the capacitive touch panel 11 based on the first touch sensing information generated in step S10. When step S11 determines that there is no liquid on the capacitive touch panel 11, the process returns to step S10 to continue scanning the capacitive touch panel 11. When step S11 determines that there is liquid on the capacitive touch panel 11, step S12 is performed. In the prior art, there are already many methods for determining whether there is liquid on the capacitive touch panel 11, so they will not be described in detail here.

[0012] Step S12 further determines the type of liquid 21, for example, whether the liquid 21 is water or salt water. In one embodiment, since water and salt water have different conductivity, the liquid 21 can be determined to be water or salt water by scanning the capacitive touch panel 11 with signals of different frequencies. For example, the controller 12 first provides a first frequency drive signal to perform a first mutual capacitance scan on the capacitive touch panel 11 to generate a first mutual capacitance sensing information, and then performs a second mutual capacitance scan on the capacitive touch panel 11 with a second frequency drive signal to generate a second mutual capacitance sensing information, wherein the first frequency is different from the second frequency. The controller 12 can determine whether the liquid 21 is water or salt water based on the first mutual capacitance sensing information and the second mutual capacitance sensing information. When water is on the capacitive touch panel 11, the presence of water can be detected when scanning the capacitive touch panel 11 with a low-frequency drive signal, but water will not be detected when scanning the capacitive touch panel 11 with a high-frequency drive signal. When salt water is on the capacitive touch panel 11, it can be detected by scanning the capacitive touch panel 11 with both low-frequency and high-frequency drive signals. Therefore, the controller 12 can determine whether the liquid 21 is water or salt water based on the first and second mutual capacitance sensing information. In one embodiment, the first frequency is 100K~200K and the second frequency is 500K~700KHz, but the present invention is not limited to this. In this embodiment, only the determination of whether the liquid 21 is water or salt water is taken as an example, but the present invention is not limited to this. The controller 12 can scan the capacitive touch panel 11 by applying drive signals of different frequencies and identify different liquids based on the scanning results.

[0013] After identifying the type of liquid 21, step S13 is executed. In step S13, a scanning strategy is determined based on the type of liquid 21. Different scanning strategies use different frequencies of periodic signals Sp. In one example, in addition to the different frequencies of periodic signals Sp, the parameters used by the algorithm are also different in different scanning strategies. The algorithm is used to calculate the sensing quantity or contact position.

[0014] Step S14 is executed after the scanning strategy is determined. Step S14 activates the signal source 13 to provide a periodic signal Sp according to the scanning strategy determined in step S13. The frequency of the periodic signal Sp is determined according to the scanning strategy determined in step S13. For example, if step S13 determines to use a first scanning strategy when the liquid 21 is water, the frequency of the periodic signal Sp in step S14 is set to 1.2MHz to 2MHz according to the first scanning strategy. Alternatively, if step S13 determines to use a second scanning strategy when the liquid 21 is brine, the frequency of the periodic signal Sp in step S14 is set to 10MHz to 100MHz according to the second scanning strategy. In one embodiment, the controller 12 is coupled to the signal source 13, and the controller executes the aforementioned steps S11 to S14 and controls the signal source 13 to generate the periodic signal Sp.

[0015] Step S15 is executed after the signal source 13 is activated to provide a periodic signal Sp. In step S15, the controller 12 scans the capacitive touch panel 11 to generate a second touch sensing information. The second touch sensing information includes the sensing values ​​of multiple electrodes of the capacitive touch panel 11. The scan performed in step S15 does not apply a drive signal to the capacitive touch panel 11, but only senses all electrodes within the capacitive touch panel 11. Referring to FIG4, during the scan in step S15, the periodic signal Sp provided by the signal source 13 is coupled to the user, so that the periodic signal Sp is further coupled to the capacitive touch panel 11 via the user's finger 20. At this time, the user's finger 20 is equivalent to an active stylus that emits signals. When a user's finger 20 touches the capacitive touch panel 11 and the liquid 21, the frequency of the periodic signal Sp is determined by the type of liquid 21. Therefore, the periodic signal Sp cannot be transmitted to the capacitive touch panel 11 through the liquid 21. Instead, it couples with the electrodes 113 of the capacitive touch panel 11 at the point of contact of the finger 20. This results in the sensing intensity of electrode 113 being greater than that of other electrodes 111, 112, 114, 115, and 116. Therefore, the touch sensing system 10 can accurately determine the contact position of the finger 20 based on the second touch information, without being interfered with by the liquid 21.

[0016] When the continuous startup time of the signal source 13 reaches a preset value or the number of times the capacitive touch panel 11 is scanned reaches a preset value, step S16 is executed to turn off the signal source 13, and then the process returns to step S10.

[0017] In one embodiment, the touch system 10 includes a conductor connected to a signal source 13. This conductor is for user contact, allowing a periodic signal Sp from the signal source 13 to be coupled to the user through the conductor. Figure 5 shows an embodiment of coupling the periodic signal Sp from the signal source to the user. In Figure 5, the touch sensing system 10 of the present invention is applied in a smartphone 30. The smartphone 30 includes a touch screen 31, a metal frame 32, a metal button 33, and a metal back cover (not shown). The touch screen 31 includes a capacitive touch panel 11 of the touch sensing system 10. The controller 12 and the signal source 13 of the touch sensing system 10 are disposed within the housing of the smartphone 30. The signal source 13 is connected to the metal frame 32, the metal button 33, and / or the metal back cover. In this embodiment, the metal frame 32, the metal button 33, and / or the metal back cover are conductors connecting to the signal source 13. When a user holds a smartphone 30 with their left hand 40 and operates the touch screen 31 with their right hand 41 fingers 20, the periodic signal Sp from the signal source 13 can be transmitted from the left hand 40, which is in contact with the metal frame 32, the metal buttons 33 and / or the metal back cover, to the right hand 41 fingers 20.

[0018] In one embodiment, the touch system 10 further includes an antenna-connected signal source 13, which is used to couple the periodic signal Sp to the user. The antenna may be, for example, an NFC (Near Field Communication) circuit of a smartphone 30, an electrode of the capacitive touch panel 11, or other signal-transmitting antenna. The signal source 13 can be connected to the NFC circuit, the electrode of the capacitive touch panel 11, and / or the antenna to transmit the periodic signal Sp to the user. The embodiment in FIG6 illustrates using the electrodes of the capacitive touch panel as the antenna connecting the signal source 13. In FIG6, the capacitive touch panel 11 includes a plurality of electrodes X1~X11 arranged in a horizontal direction (X direction) and a plurality of electrodes Y1~Y14 arranged in a vertical direction (Y direction), wherein electrodes X1~X11 are perpendicular to electrodes Y1~Y14. Electrode X1 is located on the left edge of the capacitive touch panel 11, electrode X11 is located on the right edge of the capacitive touch panel 11, electrode Y1 is located on the upper edge of the capacitive touch panel 11, and electrode Y14 is located on the lower edge of the capacitive touch panel 11. The left edge is adjacent to both the upper and lower edge areas, and the right edge is also adjacent to both the upper and lower edge areas. When performing steps S14 and S15 of FIG. 3, the signal source 13 can transmit a periodic signal Sp to the user through the electrodes of the capacitive touch panel 11. Specifically, during the first time period, the signal source 13 connects to electrodes X1 and / or X11 to transmit the periodic signal Sp to the user through electrodes X1 and / or X11. Simultaneously, the touch sensing system 10 acquires the sensing values ​​of electrodes X2 to X10 that are not connected to the signal source. During the second time period, the signal source 13 is connected to electrode Y1 and / or electrode Y14 to transmit a periodic signal Sp to the user through electrode Y1 and / or electrode Y14. At the same time, the touch sensing system 10 will obtain the sensing amount of electrodes Y2 to Y13 that are not connected to the signal source.

[0019] In one embodiment, the signal source 13 can be disposed on different electronic devices, such as the capacitive touch panel 11 and the controller 12. For example, the capacitive touch panel 11 and the controller 12 can be disposed on a smartphone, while the signal source 13 can be disposed on a wearable electronic device, including but not limited to a smartwatch, earphones, and a ring. Specifically, the controller 12 can activate the signal source 13 in the smartwatch through a wireless communication device (such as Bluetooth) provided by the smartphone. The signal source 13 then provides a periodic signal Sp to the conductor in the smartwatch that is in contact with the user's skin, or transmits it to the user through the antenna of the smartwatch.

[0020] In one embodiment, the signal source 13 can transmit a periodic signal Sp through different devices in the electronic device. For example, a laptop computer has a touch screen and a touchpad. When the user is using the touch screen, the signal source 13 can transmit a periodic signal Sp to the user through the electrodes of the touchpad. Conversely, when the user is using the touchpad, the signal source 13 can transmit a periodic signal Sp to the user through the electrodes of the touch screen.

[0021] The main body executing each step of FIG. 1 can have many variations and combinations, and is not limited to the embodiments provided in this specification. In one embodiment, steps S11 to S14 are performed by controller 12. In another embodiment, an electronic device (e.g., a smartphone) includes the capacitive touch panel 11 and controller 12. The scanning result of step S10 (including multiple sensing quantities sensed from the capacitive touch panel 11) is sent to the host of the electronic device (e.g., a central processing unit), and the host performs steps S11 to S14. In one embodiment, steps S11 to S13 are performed by controller 12, which transmits the determined scanning strategy or the contents of the scanning strategy (e.g., the frequency of the periodic signal Sp) to the aforementioned host, and the host implements step S14.

[0022] The method of Figure 1 can also be implemented by the embodiment shown in Figure 7. The touch sensing system 50 of Figure 7 includes a capacitive touch panel 51, a controller 52, and a signal source 53. The controller 52 is connected to the capacitive touch panel 51 and is used to scan the capacitive touch panel 51. The controller 52 has a high-voltage terminal 522 and a low-voltage terminal 524, and the combination of the high-voltage terminal 522 and the low-voltage terminal 524 is used to provide power to the controller 52. In one embodiment, the low-voltage terminal 524 is a ground terminal, and the high-voltage terminal 522 provides the operating voltage VDD of the controller 52. The signal source 53 is connected to the controller 52 and is used to provide a periodic signal Sp to the high-voltage terminal 522 and the low-voltage terminal 524. Since the periodic signal Sp is applied to the high-voltage terminal 522 and the low-voltage terminal 524 simultaneously, the voltage difference between the high-voltage terminal 522 and the low-voltage terminal 524 does not change. The composition of the capacitive touch panel 51 and the signal source 53 can be found in the description of the capacitive touch panel 11 and the signal source 13 mentioned above, and will not be repeated here.

[0023] The operation of the system shown in FIG. 7 will be explained below with reference to FIG. 1. In step S10, the controller 52 scans the capacitive touch panel 51 to generate a first touch sensing information. The first touch sensing information includes the sensing values ​​of multiple electrodes of the capacitive touch panel 51. The scan performed in step S10 includes, but is not limited to, mutual capacitance scanning. In step S11, the controller 52 determines whether there is liquid on the capacitive touch panel 51 based on the first touch sensing information. When the controller 52 determines that there is no liquid on the capacitive touch panel 51, it returns to step S10 to continue scanning the capacitive touch panel 51. When the controller 52 determines that there is liquid on the capacitive touch panel 51, it proceeds to step S12.

[0024] In step S12, the controller 52 determines the type of liquid on the capacitive touch panel 51. After the controller 52 identifies the type of liquid, step S13 is executed. In step S13, the controller 52 determines a scanning strategy based on the type of liquid. The frequency of the periodic signal Sp used by different scanning strategies will also be different.

[0025] After the controller 52 determines the scanning strategy, it executes step S14. In step S14, the controller 52 starts the signal source 53 according to the scanning strategy determined in step S13, so that the signal source 53 provides a periodic signal Sp to the high voltage terminal 522 or the high voltage terminal 522 and the low voltage terminal 524 of the controller 52.

[0026] After step S14, the controller 52 executes step S15 to scan the capacitive touch panel 51 to generate second touch sensing information, which includes the sensing values ​​of multiple electrodes of the capacitive touch panel 51. The scan performed in step S15 does not apply a drive signal to the capacitive touch panel 51; it only senses all electrodes within the capacitive touch panel 51. The high-voltage terminal 522 and the low-voltage terminal 524, which provide power to the controller 52, are simultaneously subjected to a periodic signal Sp, causing the potential of the electrodes to be sensed on the capacitive touch panel 51 to change periodically. The user acts as another ground terminal; when their finger touches the capacitive touch panel 51, some of the charge on the electrode corresponding to the contact position is carried away. Even without applying a drive signal to the capacitive touch panel 51, the contact position of the finger can still be determined based on the results obtained from sensing all electrodes. During the scanning process in step S15, at locations without finger contact, the periodic signal Sp exists simultaneously at both the high-voltage end 522 and the low-voltage end 524, therefore the periodic signal Sp does not affect the sensing quantity of the electrodes at these locations. At locations with finger contact, since the human body can be considered as another ground potential GND2, the signal source 53 effectively provides the periodic signal Sp to the user's finger, as shown by signal source 13 in Figure 4. Because the frequency of the periodic signal Sp is determined based on the type of liquid, the controller 52 can correctly determine the contact position of the finger 20 based on the second touch sensing information without being interfered with by the liquid 21.

[0027] In step S15, when the continuous start time of the signal source 53 reaches a preset value or the number of scans reaches a preset value, the controller 52 executes step S16 to shut down the signal source 53, and then returns to step S10.

[0028] The signal source 53 in Figure 7 can share a power supply with the controller 52, as shown in the embodiment in Figure 8. Compared to the touch sensing system 50 in Figure 7, the embodiment in Figure 8 further includes a first filter 55 and a second filter 56. The first filter 55 includes, but is not limited to, an inductor L1, and the second filter 56 includes, but is not limited to, an inductor L2. The first filter 55 is coupled between the high-voltage terminal 522 and the signal source 53, and the second filter 56 is coupled between the low-voltage terminal 524 and the signal source 53. The first filter 55 is used to prevent the periodic signal Sp from being fed back from the high-voltage terminal 522 to the signal source 53. The second filter 56 is used to prevent the periodic signal Sp from being fed back from the low-voltage terminal 524 to the signal source 53. In one embodiment, when the high-voltage terminal 522 and the low-voltage terminal 524 are sufficiently close, the signal source 13 can provide only the periodic signal Sp to the high-voltage terminal 522. The periodic signal Sp on the high-voltage terminal 522 can be coupled to the low-voltage terminal 524 via the coupling capacitor C6, so the second filter 56 can be omitted.

[0029] As can be understood from the operation of the embodiment in Figure 7 above, the control method of the touch sensing system 50 mainly includes: A. providing a periodic signal to the high-voltage terminal 522 of the controller 52 or the high-voltage terminal 522 and the ground terminal 524; and B. scanning the capacitive touch panel 51 with the controller 52 to generate touch sensing information. In step B, the controller 52 does not apply a driving signal to the capacitive touch panel 51.

[0030] Details regarding the execution of steps S10 to S12 of Figure 1 by the controller 52. Please refer to the description of Figure 1 above, and it will not be elaborated here.

[0031] In the embodiment of FIG. 2 above, when liquid is present on the surface of the capacitive touch panel 11, the periodic signal Sp is coupled to the user, and then step S15 of FIG. 1 is performed. In the embodiment of FIG. 7, when liquid is present on the surface of the capacitive touch panel 51, the periodic signal Sp is provided to the high-voltage terminal 522 of the controller, or the high-voltage terminal 522 and the low-voltage terminal 524. However, the present invention is not limited thereto. In other embodiments, the capacitive touch panel is used in situations where liquid is likely to be present, such as rainy days or marine environments. Even if there is no liquid on the surface of the capacitive touch panel, steps S13 to S15 or steps S14 to S15 of FIG. 1 can be performed directly. In other words, it is possible to omit steps S10 to S13 and step S16 of FIG. 1.

[0032] Step S15 senses only all electrodes within the capacitive touch panel. As in the previous embodiment, the capacitive touch panel includes m electrodes in the X direction and n electrodes in the Y direction. The scanning result of step S15 includes the sensing quantity of each electrode, that is, m+n sensing quantities. The contact position of the finger can be calculated based on these m+n sensing quantities.

[0033] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above by way of embodiment, it is not intended to limit the present invention. Anyone with ordinary knowledge in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention. [Simplified Explanation of the Diagram]

[0008] Figure 1 shows a control method for the touch sensing system of the present invention. Figure 2 shows a first embodiment of the touch sensing system of the present invention. Figure 3 shows an embodiment of the signal source of Figure 2. Figure 4 shows an embodiment with liquid on the capacitive touch panel of Figure 1. Figure 5 shows an embodiment of the touch sensing system of the present invention applied to a smartphone. Figure 6 is an embodiment of a capacitive touch panel. Figure 7 shows a second embodiment of the touch sensing system of the present invention. Figure 8 shows an embodiment where the signal source and controller of Figure 7 share a power supply.

Claims

1. A touch sensing system, comprising: A capacitive touch panel; A controller, connected to the capacitive touch panel, is used to scan the capacitive touch panel; And a signal source for providing a periodic signal coupled to a user, such that the periodic signal is coupled to the capacitive touch panel via the user; wherein, after the signal source is activated to provide the periodic signal, the controller does not apply a drive signal to the capacitive touch panel, but only senses all the electrodes in the capacitive touch panel.

2. The touch sensing system as claimed in claim 1 further includes a conductor connected to the signal source, the conductor being designed for contact by the user.

3. The touch sensing system as claimed in claim 1 further includes an antenna connected to the signal source, the antenna being used to couple the periodic signal to the user.

4. The touch sensing system as claimed in claim 1, wherein the capacitive touch panel includes a first electrode and a second electrode, the first electrode being located in a first edge region of the capacitive touch panel, the second electrode being located in a second edge region of the capacitive touch panel, the first edge region being adjacent to the second edge region, and the first electrode being perpendicular to the second electrode; wherein in a first time period, the signal source is connected to the first electrode, and in a second time period following the first time period, the signal source is connected to the second electrode.

5. The touch sensing system as described in claim 1, wherein the signal source comprises: An oscillator used to generate an oscillating signal; And a boost circuit connected to the oscillator to boost the oscillation signal to generate the periodic signal.

6. The touch sensing system as claimed in claim 1, wherein the controller is coupled to the signal source and activates the signal source when liquid is present on the surface of the capacitive touch panel.

7. The touch sensing system as claimed in claim 6, wherein when the liquid is water, the frequency of the periodic signal provided by the signal source is between 1.2 MHz and 2 MHz.

8. The touch sensing system as claimed in claim 6, wherein when the liquid is salt water, the frequency of the periodic signal provided by the signal source is between 10 MHz and 100 MHz.

9. The touch sensing system as claimed in claim 6, wherein the controller performs a first mutual capacitive scan of the capacitive touch panel with a drive signal at a first frequency to generate a first mutual capacitive sensing information, and performs a second mutual capacitive scan of the capacitive touch panel with a drive signal at a second frequency to generate a second mutual capacitive sensing information, wherein the first frequency is different from the second frequency, and the controller determines whether the liquid is water or salt water based on the first mutual capacitive sensing information and the second mutual capacitive sensing information.

10. A touch sensing system, comprising: A capacitive touch panel; A controller, connected to the capacitive touch panel, is used to scan the capacitive touch panel. The controller includes a high-voltage terminal and a low-voltage terminal, the combination of which is used to provide power to the controller; and a signal source is used to provide a periodic signal to the high-voltage terminal or the combination of the high-voltage terminal and the low-voltage terminal.

11. The touch sensing system as claimed in claim 10, wherein the signal source comprises: An oscillator used to generate an oscillating signal; And a boost circuit connected to the oscillator to boost the oscillation signal to generate the periodic signal.

12. The touch sensing system of claim 10 further includes a first filter coupled between the high-voltage terminal and the signal source, the first filter being used to prevent the periodic signal from being fed back from the high-voltage terminal to the signal source.

13. The touch sensing system as claimed in claim 10, wherein the signal source is controlled by the controller, which activates the signal source when liquid is present on the surface of the capacitive touch panel.

14. The touch sensing system as claimed in claim 13, wherein when the liquid is water, the frequency of the periodic signal provided by the signal source is between 1.2 MHz and 2 MHz.

15. The touch sensing system of claim 13, wherein when the liquid is salt water, the frequency of the periodic signal provided by the signal source is between 10 MHz and 100 MHz.

16. The touch sensing system of claim 13, wherein the controller performs a first mutual capacitive scan of the capacitive touch panel with a drive signal at a first frequency to generate a first mutual capacitive sensing information, and performs a second mutual capacitive scan of the capacitive touch panel with a drive signal at a second frequency to generate a second mutual capacitive sensing information, the first frequency being different from the second frequency, and the controller determines whether the liquid is water or salt water based on the first mutual capacitive sensing information and the second mutual capacitive sensing information.

17. A control method for a touch sensing system, the touch sensing system comprising a capacitive touch panel and a controller, the controller being coupled to the capacitive touch panel and having a high-voltage terminal and a low-voltage terminal, the combination of the high-voltage terminal and the low-voltage terminal being used to provide power to the controller, the control method comprising the following steps: A. providing a periodic signal to the high-voltage terminal or the high-voltage terminal and the low-voltage terminal of the controller; and B. scanning the capacitive touch panel using the controller.

18. The control method as described in claim 17 further includes performing step A only when liquid is present on the surface of the capacitive touch panel.

19. The control method as claimed in claim 18, wherein when the liquid is water, the frequency of the periodic signal is between 1.2 MHz and 2 MHz.

20. The control method as claimed in claim 18, wherein when the liquid is salt water, the frequency of the periodic signal is between 10 MHz and 100 MHz.

21. The control method as described in claim 20, wherein the step of determining that the liquid is saline solution includes: A first mutual capacitance scan is performed on the capacitive touch panel using a driving signal at a first frequency to generate first mutual capacitance sensing information; a second mutual capacitance scan is performed on the capacitive touch panel using a driving signal at a second frequency, the second frequency being different from the first frequency; and the liquid is determined to be salt water based on the first mutual capacitance sensing information and the second mutual capacitance sensing information.

22. A control method for a touch sensing system, the touch sensing system including a capacitive touch panel, the control method comprising: A. Provide a periodic signal coupled to a user, such that the periodic signal is coupled to the capacitive touch panel via the user; And B. Scan the capacitive touch panel; wherein, the scan performed in step B does not apply a driving signal to the capacitive touch panel, but only senses all the electrodes in the capacitive touch panel.

23. The control method as described in claim 22 further includes performing step A only when liquid is present on the surface of the capacitive touch panel.

24. The control method as claimed in claim 23, wherein when the liquid is water, the frequency of the periodic signal is between 1.2 MHz and 2 MHz.

25. The control method as claimed in claim 23, wherein when the liquid is salt water, the frequency of the periodic signal is between 10 MHz and 100 MHz.

26. The control method as claimed in claim 25, wherein the step of determining that the liquid is saline solution includes: A first mutual capacitance scan is performed on the capacitive touch panel using a driving signal at a first frequency to generate first mutual capacitance sensing information; a second mutual capacitance scan is performed on the capacitive touch panel using a driving signal at a second frequency, the second frequency being different from the first frequency; and the liquid is determined to be salt water based on the first mutual capacitance sensing information and the second mutual capacitance sensing information.

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