Method and device for detecting capacitive touch screen

• US 9,024,911 B2
• Filed: 07/10/2012
• Issued: 05/05/2015
• Est. Priority Date: 05/18/2012
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: Chang, Chin-Fu
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): Lin, Chun-Nan
• Application Number:
  US13/545,291
• Publication Number:
  US 20130307814A1
• Time in Patent Office: 1,029 Days
• Field of Search: 345173-178
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A detecting device and method for a capacitive touch screen is proposed. A plurality of frequency settings is employed. Each frequency setting corresponds to a type of driving mode of a type of driving potential. These frequency settings are used for setting the detecting device for the capacitive touch screen. When the signal-to-noise (S/N) ratio of the signals in the capacitive touch screen is not appropriate, frequency settings are changed by selecting one that yields a more appropriate S/N ratio among the frequency settings. The driving mode includes a single-electrode driving mode in which only a single driving electrode in the capacitive touch screen is driven at a time, and a multiple-electrode driving mode in which multiple driving electrodes are simultaneously driven at a time, and there can be several types of driving potentials.

Claims

1. A detecting device for a capacitive touch screen, comprising:

a storage circuit for storing a plurality of frequency settings based on power consumption of the capacitive touch screen, each frequency setting corresponding to one of a plurality of driving modes, and each frequency setting including a frequency and a set of parameters, wherein each driving mode corresponds to a driving potential with a working frequency;

a driving circuit for providing a driving signal to at least one driving electrode of the capacitive touch screen according to the working frequency, wherein the capacitive touch screen includes a plurality of driving electrodes and a plurality of detecting electrodes crossing each other at a plurality of intersections; and

a detecting circuit including;

initializing settings of the detecting circuit based on the set of parameters of one of the frequency settings;

detecting signals from the detecting electrodes based on a set of parameters of the detecting circuit and generating a 1D sensing information based on the signals from the detecting electrodes;

determining if one, the sum, or the average of all the values of the 1D sensing information during noise detection exceeds a tolerable threshold; and

if the tolerable threshold is exceeded, including;

sequentially changing the working frequency and the settings of the detecting circuit based on the frequency and the set of parameters of one of the frequency settings and thereafter generating a 1D sensing information and determining if the tolerable threshold is still exceeded until the tolerable threshold is not exceeded;

or

sequentially changing the working frequency and the settings of the detecting circuit based on the frequency and the set of parameters of each of the frequency settings and thereafter generating a 1D sensing information and determining if the tolerable threshold is still exceeded, and changing the working frequency and the settings of the detecting circuit to the frequency and the set of parameters of the frequency setting that has the lowest noise interference.

2. The detecting device of claim 1, wherein the 1D sensing information used for determining if the tolerable threshold is exceeded is generated when no driving signal is provided to the driving electrodes.

3. The detecting device of claim 1, wherein one driving potential includes several driving modes, the driving mode includes a single-electrode driving mode and a two-electrode driving mode, wherein in the single-electrode driving mode, the driving signal is provided to only one of the driving electrodes at a time, while in the two-electrode driving mode, the driving signal is simultaneously provided to a pair of the driving electrodes at a time.

4. The detecting device of claim 3, wherein the power consumption for the single-electrode driving mode is less than the power consumption for the two-electrode driving mode.

5. The detecting device of claim 3, wherein in the single-electrode driving mode, the detecting circuit generates the 1D sensing information when each driving electrode is provided with the driving signal, forming a full image, and wherein in the two-electrode driving mode, the detecting circuit generates the 1D sensing information when each pair of the driving electrodes is provided with the driving signal, forming a reduced image, wherein the number of pixels in the reduced image is smaller than the number of pixels in the full image.

6. The detecting device of claim 5, wherein in the two-electrode driving mode, the detecting circuit further includes driving electrodes at both sides, and when the single driving electrode at either side is driven, detecting the signals of all the detecting electrodes to generate a 1D sensing information, wherein the two 1D sensing information generated from the driving of the electrodes at both sides are placed outside either end of the reduced image to construct an expanded image, and the number of pixels in the expanded image is greater than the number of pixels in the full image.

7. The detecting device of claim 1, wherein the driving potential includes a first driving potential and a second driving potential, wherein the power consumption for generating the full image in the single-electrode driving mode of the first driving potential>

the power consumption for generating the reduced image in the two-electrode driving mode of the first driving potential>

the power consumption for generating the full image in the single-electrode driving mode of the second driving potential.

8. The detecting device of claim 1, wherein the driving potential includes a first driving potential and a second driving potential, wherein the power consumption for generating the full image in the single-electrode driving mode of the first driving potential>

the power consumption for generating the full image in the single-electrode driving mode of the second driving potential.

9. The detecting device of claim 1, wherein the signal of each detecting electrode is passed through a variable resistor before providing to the detecting circuit, the detecting circuit sets an impedance of the variable resistor based on the set of parameter of one of the frequency settings.

10. The detecting device of claim 1, wherein the signals of the detecting electrodes are amplified by at least one amplifier before being detected by the detecting circuit, the detecting circuit sets a gain of the amplifier based on the set of parameter of one of the frequency settings.

11. The detecting device of claim 1, wherein the driving signal is generated based on the set of parameter of one of the frequency settings.

12. The detecting device of claim 1, wherein each value of the 1D sensing information is generated based on the signals of the detecting electrodes in a predetermined period, wherein the predetermined period is based on the set of parameter of one of the frequency settings.

13. The detecting device of claim 1, wherein each value of the 1D sensing information is generated based on the signals of the detecting electrodes in a predetermined phase, wherein the predetermined phase is based on the set of parameter of one of the frequency settings.

14. A detecting method for a capacitive touch screen, comprising:

storing a plurality of frequency settings based on a-level of power consumption of the capacitive touch screen, each frequency setting corresponding to one of a plurality of driving modes, and each frequency setting including a frequency and a set of parameters, wherein each driving mode corresponds to a driving potential with a working frequency;

providing a driving signal to at least one driving electrode of the capacitive touch screen according to the working frequency, wherein the capacitive touch screen includes a plurality of driving electrodes and a plurality of detecting electrodes crossing each other at a plurality of intersections; and

initializing settings of a detecting circuit based on the set of parameters of one of the frequency settings;

detecting signals from the detecting electrodes based on a set of parameters of the detecting circuit and generating a 1D sensing information based on the signals from the detecting electrodes;

determining if one, the sum, or the average of all the values of the 1D sensing information during noise detection exceeds a tolerable threshold; and

if the tolerable threshold is exceeded, including;

sequentially changing the working frequency and the settings of the detecting circuit based on the frequency and the set of parameters of one of the frequency settings and thereafter generating a 1D sensing information and determining if the tolerable threshold is still exceeded until the tolerable threshold is not exceeded;

or

sequentially changing the working frequency and the settings of the detecting circuit based on the frequency and the set of parameters of each of the frequency settings and thereafter generating a 1D sensing information and determining if the tolerable threshold is still exceeded, and changing the working frequency and the settings of the detecting circuit to the frequency and the set of parameters of the frequency setting that has the lowest noise interference.

15. The detecting method of claim 14, wherein the 1D sensing information used for determining if the tolerable threshold is exceeded is generated when no driving signal is provided to the driving electrodes.

16. The detecting method of claim 14, wherein one driving potential includes several driving modes, the driving mode includes a single-electrode driving mode and a two-electrode driving mode, wherein in the single-electrode driving mode, the driving signal is provided to only one of the driving electrodes at a time, while in the two-electrode driving mode, the driving signal is simultaneously provided to a pair of the driving electrodes at a time.

17. The detecting method of claim 16, wherein the power consumption for the single-electrode driving mode is less than the power consumption for the two-electrode driving mode.

18. The detecting method of claim 16, wherein in the single-electrode driving mode, the detecting circuit generates the 1D sensing information when each driving electrode is provided with the driving signal, forming a full image, and wherein in the two-electrode driving mode, the detecting circuit generates the 1D sensing information when each pair of the driving electrodes is provided with the driving signal, forming a reduced image, wherein the number of pixels in the reduced image is smaller than the number of pixels in the full image.

19. The detecting method of claim 18, wherein in the two-electrode driving mode, the detecting circuit further includes driving electrodes at both sides, and when the single driving electrode at either side is driven, detecting the signals of all the detecting electrodes to generate a 1D sensing information, wherein the two 1D sensing information generated from the driving of the electrodes at both sides are placed outside either end of the reduced image to construct an expanded image, and the number of pixels in the expanded image is greater than the number of pixels in the full image.

20. The detecting method of claim 14, wherein the driving potential includes a first driving potential and a second driving potential, wherein the level of power consumption for generating the full image in the single-electrode driving mode of the first driving potential>

the power consumption for generating the reduced image in the two-electrode driving mode of the first driving potential>

the power consumption for generating the full image in the single-electrode driving mode of the second driving potential.

21. The detecting method of claim 14, wherein the driving potential includes a first driving potential and a second driving potential, wherein the level of power consumption for generating the full image in the single-electrode driving mode of the first driving potential>

the power consumption for generating the full image in the single-electrode driving mode of the second driving potential.

22. The detecting method of claim 14, wherein the signal of each detecting electrode is passed through a variable resistor before providing to the detecting circuit, the detecting circuit sets an impedance of the variable resistor based on the set of parameter of one of the frequency settings.

23. The detecting method of claim 14, wherein the signals of the detecting electrodes are amplified by at least one amplifier before being detected by the detecting circuit, the detecting circuit sets a gain of the amplifier based on the set of parameter of one of the frequency settings.

24. The detecting method of claim 14, wherein the driving signal is generated based on the set of parameter of one of the frequency settings.

25. The detecting method of claim 14, wherein each value of the 1D sensing information is generated based on the signals of the detecting electrodes in a predetermined period, wherein the predetermined period is based on the set of parameter of one of the frequency settings.

26. The detecting method of claim 14, wherein each value of the 1D sensing information is generated based on the signals of the detecting electrodes in a predetermined phase, wherein the predetermined phase is based on the set of parameter of one of the frequency settings.