Predictive Touch Surface Scanning

• US 20120154324A1
• Filed: 09/30/2011
• Published: 06/21/2012
• Est. Priority Date: 07/28/2009
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Wright, David G., Kolokowsky, Steven, Grivna, Edward L.
• Granted Patent: US 8,723,825 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/041661 using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window
• CPC Class Codes: G06F 3/041662 using alternate mutual and self-capacitive scanning
• 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 method for locating a conductive object at a touch-sensing surface may include detecting a first resolved location for the conductive object at the touch-sensing surface based on a first scan of the touch-sensing surface, predicting a location for the conductive object, and determining a second resolved location for the conductive object by performing a second scan of a subset of sensor elements of the touch-sensing surface, wherein the subset of sensor elements is selected based on the predicted location of the conductive object.

Claims

1. A method, comprising:

based on a first scan of the touch-sensing surface, determining a first resolved location for a conductive object proximate to a touch-sensing surface;

predicting a location for the conductive object; and

determining a second resolved location for the conductive object by performing a second scan of a subset of sensor elements of the touch-sensing surface, wherein the subset of sensor elements is selected based on the predicted location of the conductive object.

2. The method of claim 1, wherein the subset of sensor elements includes sensor elements that intersect with other sensor elements within an area surrounding the predicted location.

3. The method of claim 1, wherein predicting the location for the conductive object comprises calculating a velocity of the conductive object.

4. The method of claim 1, wherein predicting the location for the conductive object comprises selecting the first resolved location as the predicted location.

5. The method of claim 1, wherein predicting the location for the conductive object comprises calculating an acceleration of the conductive object.

6. The method of claim 1, further comprising:

tracking a resolved location of the conductive object by performing a series of mutual capacitance scans, wherein the second scan is one of the series of mutual capacitance scans; and

detecting an additional conductive object proximate to the touch-sensing surface by scanning for a new contact over at least a portion of the touch-sensing surface during a time between mutual capacitance scans of the series of mutual capacitance scans.

7. The method of claim 6, wherein scanning for the new contact comprises:

electrically coupling a set of sensor elements to each other, and

measuring a self-capacitance of the electrically coupled set of sensor elements.

8. The method of claim 6, wherein the self-capacitance scan includes a second subset of sensor elements representing fewer than all of the sensor elements of the touch-sensing surface.

9. A method, comprising:

determining a location of a conductive object proximate to a touch-sensing surface based on a first scan of the touch-sensing surface;

calculating a search window of predicted locations of the conductive object based on a time duration between the first scan and a second scan; and

performing the second scan, wherein the second scan includes intersections of sensor elements, wherein the intersections are within the search window.

10. The method of claim 9, wherein the search window includes intersections of sensor elements within an area surrounding the predicted location.

11. The method of claim 9, wherein calculating the search window comprises calculating a velocity of the conductive object.

12. The method of claim 9, wherein calculating the search window comprises calculating an acceleration of the conductive object.

13. The method of claim 9, further comprising:

tracking a resolved location of the conductive object by performing a series of mutual capacitance scans, wherein the second scan is one of the series of mutual capacitance scans; and

detecting an additional conductive object at the touch-sensing surface by performing a self-capacitance scan of at least a portion of the touch-sensing surface between mutual capacitance scans of the series of mutual capacitance scans.

14. The method of claim 9, further comprising, in response to determining that the conductive object is not located within the search window, expanding the search window by scanning additional intersections of sensor elements.

15. The method of claim 14, wherein the search window is expanded to include the entire touch-sensing surface.

16. The method of claim 14, wherein the search window is expanded based on a direction of movement of the conductive object.

17. The method of claim 14, wherein the search window is expanded to include additional intersections nearest an intersection having a highest measured capacitance value.

18. A touch-sensing system comprising:

a capacitive sensor array comprising a plurality of sensor elements;

a capacitance sensor configured to measure capacitance for each of a plurality of intersections between individual sensor elements of the plurality of sensor elements; and

processing logic configured to determine a resolved location of a conductive object based on scanning a subset of intersections within a search window, wherein the search window defines an area around a predicted location of the conductive object.

19. The touch-sensing system of claim 18, wherein the predicted location is extrapolated based on at least one previously determined location of the conductive object.

20. The touch-sensing system of claim 18, wherein the capacitance sensor is further configured to:

perform the second scan as one of a series of mutual capacitance scans, and

perform a self-capacitance scan of at least a portion of the touch-sensing surface between mutual capacitance scans of the series of mutual capacitance scans; and

wherein the processing logic is further configured to;

track a resolved location of the conductive object over time based on the series of mutual capacitance scans, and

detect an additional conductive object at the touch-sensing surface based on the self-capacitance scan.