SYSTEM AND METHOD FOR REDUCING SHADOW EFFECTS IN TOUCH SYSTEMS

• US 20150242052A1
• Filed: 02/12/2015
• Published: 08/27/2015
• Est. Priority Date: 02/21/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gao, Qiang, Huang, William Yee-Ming, Wong, Hsun Wei David, Ng, Teresa Ka Ki, Wang, Rex, Law, Carol King Mui, Jalil, Suhail
• Granted Patent: US 9,983,731 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means
• 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

Systems, methods, and devices for reducing shadow effects in touch systems are contained herein. In one aspect, a method of reducing shadow effects in a touch system is disclosed. The method includes receiving a touch input on a touch interface, determining a difference between a weighted mean of the touch input and an arithmetic mean of the touch input and adjusting an estimated touch position of the touch input based on the difference.

Claims

1. A method of reducing shadow effects in a touch system, the method comprising:

receiving a touch input on a touch interface;

determining a weighted mean of the touch input, the weighted mean indicating an estimated touch position of the touch input on the touch interface;

determining a difference between the weighted mean of the touch input and an arithmetic mean of the touch input; and

adjusting the estimated touch position of the touch input based on the difference.

2. The method of claim 1, wherein receiving a touch input comprises receiving information from a plurality of touch sensors of the touch interface and the information from each of the plurality of touch sensors represents an x position value, a y position value, and an amplitude of the estimated touch position, and adjusting comprises adjusting one or more of the x position value, the y position value, and the amplitude of the estimated touch position based on the difference.

3. The method of claim 2, wherein adjusting the estimated touch position comprises adjusting the estimated touch position to the value of a centroid when the difference is below a first threshold and to a value based on the difference when the difference is equal to or above the first threshold.

4. The method of claim 1, further comprising receiving a plurality of touch signals indicative of the touch input;

identifying a maximum amplitude of the touch input of the plurality of touch signals;

determining the weighted mean of the touch input based on the plurality of touch signals; and

determining the arithmetic mean of the touch input.

5. The method of claim 1 wherein the touch interface is divided into a plurality of sectors by sector divisions to determine which sectors of the touch interface contain shadow effects of the touch input.

6. The method of claim 5, wherein the sector divisions pass through one of the weighted mean of the touch input and the arithmetic mean of the touch input.

7. The method of claim 5, wherein the touch interface is divided into sectors by sector divisions that pass through a sensor node of the touch interface having a maximum touch signal strength as compared to the touch signal strengths of all of the sensor nodes in the touch input.

8. The method of claim 5, further comprising:

sorting the plurality of touch signals in a descending order list such that the touch signal with the highest value occurs first in the list;

determining a maximum value of the plurality of touch signals and adding the maximum value to an extracted touch signal;

sampling the plurality of touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal if an amplitude of the sampled signal is above a second threshold; and

sampling the plurality touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal until one of a number of sampled signals reach a third threshold, a value of the touch signal is below a fourth threshold, and a value of the touch signal is below the first threshold.

9. The method of claim 8, further comprising discontinuing sampling when a difference between a value of one of the plurality of touch signals and values of neighboring touch signals is below a fifth threshold or when the number of signals in the extracted touch signal exceeds a predetermined threshold.

10. An apparatus for filtering a touch input, comprising:

a processor;

a touch device; and

a memory, operably coupled to the processor, and configured to store processor instructions that configure the processor to;

receive a touch input on a touch interface;

determine a weighted mean of the touch input, the weighted mean indicating an estimated touch position of the touch input on the touch interface;

determine a difference between the weighted mean of the touch input and an arithmetic mean of the touch input; and

adjust the estimated touch position of the touch input based on the difference.

11. The apparatus of claim 10, wherein receiving a touch input comprises receiving information from a plurality of touch sensors of the touch interface and the information from each of the plurality of touch sensors represents an x position value, a y position value, and an amplitude of the estimated touch position and the memory is further configured to store processor instructions that configure the processor to adjust one or more of the x position value, the y position value, and the amplitude of the estimated touch position based on the difference.

12. The apparatus of claim 11, wherein adjusting the estimated touch position comprises adjusting the estimated touch position to the value of the weighted mean when the difference is below a first threshold and to a value based on the difference when the difference is equal to or above the first threshold.

13. The apparatus of claim 10, wherein the memory further is configured to store processor instructions that configure the processor to:

receive a plurality of touch signals indicative of the touch input;

identify a maximum amplitude of the touch input of the plurality of touch signals;

determine the weighted mean of the touch input based on the plurality of touch signals; and

determine the arithmetic mean of the touch input.

14. The apparatus of claim 13 wherein the touch interface is divided into a plurality of sectors by sector divisions to determine which sectors of the touch interface contain shadow effects of the touch input.

15. The apparatus of claim 14, wherein the sector divisions pass through one of the weighted mean of the touch input and the arithmetic mean of the touch input.

16. The apparatus of claim 14, wherein the touch interface is divided into sectors by sector divisions that pass through a sensor node of the touch interface having a maximum touch signal strength as compared to the touch signal strengths of all of the sensor nodes in the touch input.

17. The apparatus of claim 14, wherein the memory further is configured to store processor instructions that configure the processor to:

sort the plurality of touch signals in a descending order list such that the touch signal with the highest value occurs first in the list;

determine a maximum value of the plurality of touch signals and adding the maximum value to an extracted touch signal;

sample the plurality of touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal if an amplitude of the sampled signal is above a second threshold;

sample the plurality touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal until one of a number of sampled signals reach a third threshold, a value of the touch signal is below a fourth threshold, and a value of the touch signal is below the first threshold; and

discontinuing sampling when a difference between a value of one of the plurality of touch signals and values of neighboring touch signals is below a fifth threshold.

18. A system for filtering a touch input, comprising;

a control module configured to

receive a touch input on a touch interface;

determine a weighted mean of the touch input, the weighted mean indicating an estimated touch position of the touch input on the touch interface;

determine a difference between the weighted mean of the touch input and an arithmetic mean of the touch input; and

adjust the estimated touch position of the touch input based on the difference.

19. The system of claim 18, wherein receiving a touch input comprises receiving information from a plurality of touch sensors of the touch interface and the information from each of the plurality of touch sensors represents an x position value, a y position value, and an amplitude of the estimated touch position.

20. The system of claim 19, wherein the control module is configured to adjust one or more of the x position value, the y position value, and the amplitude of the estimated touch position based on the difference, and wherein adjusting the estimated touch position comprises adjusting the estimated touch position to the value of the weighted mean when the difference is below a first threshold and to a value based on the difference when the difference is equal to or above the first threshold.

21. The system of claim 18, wherein the control module is further configured to:

receive a plurality of touch signals indicative of the touch input;

identify a maximum amplitude of the touch input of the plurality of touch signals;

determine the weighted mean of the touch input based on the plurality of touch signals; and

determine the arithmetic mean of the touch input.

22. The system of claim 21 wherein the touch interface is divided into a plurality of sectors by sector divisions to determine which sectors of the touch interface contain shadow effects of the touch input.

23. The system of claim 22, wherein the sector divisions pass through one of the weighted mean of the touch input, the arithmetic mean of the touch input, and a sensor node of the touch interface having a maximum touch signal strength as compared to the touch signal strengths of all of the sensor nodes in the touch input.

24. The system of claim 21, wherein the control module is further configured to:

sort the plurality of touch signals in a descending order list such that the touch signal with the highest value occurs first in the list;

determine a maximum value of the plurality of touch signals and adding the maximum value to an extracted touch signal;

sample the plurality of touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal if an amplitude of the sampled signal is above a second threshold;

sample the plurality touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal until one of a number of sampled signals reach a third threshold, a value of the touch signal is below a fourth threshold, and a value of the touch signal is below the first threshold; and

discontinuing sampling when a difference between a value of one of the plurality of touch signals and values of neighboring touch signals is below a fifth threshold.

25. A non-transitory computer-readable medium storing instructions that, when executed, cause at least one physical computer processor to perform a method of reducing shadow effects in a touch system, the method comprising:

receiving a touch input on a touch interface;

determining a weighted mean of the touch input, the weighted mean indicating an estimated touch position of the touch input on the touch interface;

determining a difference between the weighted mean of the touch input and an arithmetic mean of the touch input; and

adjusting the estimated touch position of the touch input based on the difference.

26. The non-transitory computer-readable medium of claim 25, wherein receiving a touch input comprises receiving information from a plurality of touch sensors of the touch interface and the information from each of the plurality of touch sensors represents an x position value, a y position value, and an amplitude of the estimated touch position.

27. The non-transitory computer-readable medium of claim 26, further comprising adjusting one or more of the x position value, the y position value, and the amplitude of the estimated touch position based on the difference, and adjusting the estimated touch position comprises adjusting the estimated touch position to the value of the weighted mean when the difference is below a first threshold and to a value based on the difference when the difference is equal to or above the first threshold.

28. The non-transitory computer-readable medium of claim 25, further comprising

receiving a plurality of touch signals indicative of the touch input;

identifying a maximum amplitude of the touch input of the plurality of touch signals;

determining the weighted mean of the touch input based on the plurality of touch signals; and

determining the arithmetic mean of the touch input.

29. The non-transitory computer-readable medium of claim 28 wherein the touch interface is divided into a plurality of sectors by sector divisions to determine which sectors of the touch interface contain shadow effects of the touch input and wherein the sector divisions pass through one of the weighted mean of the touch input, the arithmetic mean of the touch input, and a sensor node of the touch interface having a maximum touch signal strength as compared to the touch signal strengths of all of the sensor nodes in the touch input.

30. The non-transitory computer-readable medium of claim 28, further comprising:

sorting the plurality of touch signals in a descending order list such that the touch signal with the highest value occurs first in the list;

determining a maximum value of the plurality of touch signals and adding the maximum value to an extracted touch signal;

sampling the plurality of touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal if an amplitude of the sampled signal is above a second threshold;

sampling the plurality touch signals at sensor nodes adjacent to the maximum value and including the one or more neighboring signals in the extracted touch signal until one of a number of sampled signals reach a third threshold, a value of the touch signal is below a fourth threshold, and a value of the touch signal is below the first threshold; and

discontinuing sampling when a difference between a value of one of the plurality of touch signals and values of neighboring touch signals is below a fifth threshold.