HIGH-ACCURACY TOUCH POSITIONING FOR TOUCH PANELS

• US 20130176275A1
• Filed: 03/12/2012
• Published: 07/11/2013
• Est. Priority Date: 01/09/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Weaver, Glen, Ranganathan, Sumant, Cattivelli, Federico Santiago, Li, Tianhao, Kharwa, Bhupesh, Joshi, Satish Vithal, Chang, Pi Sheng, De Roche, Kerrynn Jacques
• Granted Patent: US 9,058,078 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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

Control circuitry for a touch panel includes a touch panel interface, a memory comprising touch positioning logic, and a controller in communication with the memory and the touch panel interface. The controller is operable, when the touch positioning logic is executed, to perform selected processing of the touch panel, including scanning a touch panel and determining a touch panel blob resulting from a touch, obtaining blob characteristics of the touch panel blob, and determining a position of the blob relative to the touch panel based on the blob characteristics. The blob characteristics can be adjusted to more accurately position the blob in circumstances where the blob is located near the edge of the touch panel, is in close proximity to another blob, or when the touch panel has variation in the received signal noise.

Claims

1. A method for touch positioning for a touch panel, the method comprising:

scanning a touch panel;

determining a touch panel blob resulting from a touch;

determining a member pixel of the touch panel blob based on a member-identifying threshold;

determining a peak pixel of the touch panel blob that exceeds a touch-reporting threshold; and

determining a position of the touch panel blob relative to the touch panel based on the peak pixel and the member pixel.

2. The method of claim 1, where determining the position comprises analyzing a window around the peak pixel that includes the member pixel.

3. The method of claim 2, where the window comprises a three-by-three pixel window centered on the peak pixel.

4. The method of claim 2, further comprising determining a centroid of the blob in the window;

and determining the position to be the centroid of the blob.

5. The method of claim 1, where the touch-reporting threshold is higher than the member-identifying threshold.

6. The method of claim 1, further comprising determining the member-identifying threshold using a noise floor estimate of the touch panel determined from a prior scan of the touch panel.

7. The method of claim 1, where the peak is one of multiple peaks in the touch panel blob;

and where determining a position comprises;

analyzing a window around each of the multiple peaks;

determining a centroid location for each of the windows; and

determining a position for each of the multiple peaks as the centroid locations.

8. Control circuitry for a touch panel, the control circuitry comprising:

a touch panel interface;

a memory comprising touch positioning logic; and

a controller in communication with the memory and the touch panel interface, the controller operable, when the touch positioning logic is executed, to;

scan a touch panel;

determine a touch panel blob resulting from a touch;

obtain a blob characteristic of the touch panel blob;

adjust the blob characteristic of the touch panel blob when the touch panel blob is positioned near an edge of the touch panel by adding a virtual member pixel to the touch panel blob; and

determine a position of the touch panel blob relative to the touch panel based on the blob characteristic.

9. The method of claim 8, where the virtual member pixel is a row member pixel.

10. The method of claim 8, where the virtual member pixel is a column member pixel.

11. The method of claim 8, where the controller is operable to attach the virtual member pixel to the touch panel blob at a blob attachment point.

12. The method of claim 9, where the blob characteristic comprises capacitance.

13. The method of claim 12, where the capacitance comprises a total row capacitance of a particular row in the blob.

14. The method of claim 12, where the capacitance comprises a total column capacitance of a particular column in the blob.

15. Control circuitry for a touch panel, the control circuitry comprising:

a touch panel interface;

a memory comprising touch positioning logic; and

a controller in communication with the memory and the touch panel interface, the controller operable, when the touch positioning logic is executed, to;

scan a touch panel;

determine a first touch panel blob and a second touch panel blob from the scan;

determine that the first touch panel blob and the second touch panel blob share a common member pixel;

apportion capacitance of the common member pixel between the first touch panel blob and the second touch panel blob; and

determine a position of the first touch panel blob, the second touch panel blob, or both.

16. The circuitry of claim 15, where the controller is operable to:

find a boundary between the first touch panel blob and the second touch panel blob;

determine that the boundary bisects the capacitance of the common member pixel into a first amount of capacitance and a second amount of capacitance;

apportion the first amount of capacitance to the first touch panel blob; and

apportion the second amount of capacitance to the second touch panel blob.

17. The circuitry of claim 16, where the controller is operable to determine the boundary as a vertical line.

18. The circuitry of claim 16, where the controller is operable to determine the boundary as a horizontal line.

19. The circuitry of claim 15, where the position comprises a position for the first touch panel blob, determined from characteristics of both the first touch panel blob and the second touch panel blob.

20. The circuitry of claim 15, where the controller is operable to report the position to a host processor in communication with the controller.