Predictive touch surface scanning

• US 8,723,825 B2
• Filed: 09/30/2011
• Issued: 05/13/2014
• Est. Priority Date: 07/28/2009
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kolokowsky, Steven, Grivna, Edward L., Wright, David G.
• Primary Examiner(s): Leiby, Christopher E
• Application Number:
  US13/250,379
• Publication Number:
  US 20120154324A1
• Time in Patent Office: 956 Days
• Field of Search: 345/156, 345173-174
• US Class Current: 345/173
• 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:

determining a first resolved location of a conductive object proximate to a touch-sensing surface based on self-capacitance measurements of individual sensor electrodes of the touch-sensing surface in a self-capacitance mode;

measuring first self-capacitances of a first set of sensor electrodes of the individual sensor electrodes disposed in a first axis of the touch-sensing surface; and

measuring second self-capacitances of a second set of sensor electrodes of the individual sensor electrodes disposed in a second axis of the touch-sensing surface;

in response to determining the first resolved location of the conductive object, switching from operation in the self-capacitance mode to operation in a mutual capacitance mode; and

in response to determining the first resolved location of the conductive object, tracking a movement of the conductive object over the touch-sensing surface by determining a different resolved location of the conductive object for each of a plurality of consecutive mutual capacitance measurements of pairs of the sensor electrodes of the touch sensing surface while in the mutual capacitance mode, wherein performing each of the mutual capacitance measurements comprises measuring a mutual capacitance between at least one pair of the pairs of sensor electrodes of the touch-sensing surface,

wherein the determining the first resolved location comprises;

determining that the conductive object is no longer present proximate to the touch-sensing surface during the mutual capacitance mode;

in response to the determining that the conductive object is no longer present during the mutual capacitance mode, switching from the operation in the mutual capacitance mode to the operation in the self-capacitance mode;

in response to the switching to the self-capacitance mode,

measuring third self-capacitances of the first set of sensor electrodes to detect a second presence of the conductive object or a new conductive object proximate to the touch-sensing surface; and

measuring fourth self-capacitances of the second set of sensor electrodes only when the second presence is detected in the measuring the third self-capacitances.

2. The method of claim 1, further comprising performing the self-capacitance measurements by measuring a self-capacitance for each of a plurality of sensor electrodes of the touch-sensing surface, wherein the plurality of sensor electrodes comprises the first set and the second set.

3. The method of claim 2, further comprising performing at least one of the mutual capacitance measurements, wherein the performing the at least one of the mutual capacitance measurements comprises measuring a capacitance for each of a subset of intersections between the pairs of sensor electrodes of the plurality of sensor electrodes, wherein a number of intersections in the subset of intersections is less than a number of intersections of the plurality of sensor electrodes sensed during the self-capacitance measurements.

4. The method of claim 1, wherein an area of the touch-sensing surface sensed by each of the mutual capacitance measurements is less than an area of the touch-sensing surface included by the self-capacitance measurements.

5. The method of claim 1, further comprising, based on the first resolved location of the conductive object, calculating a predicted location for the conductive object corresponding to a time at which a first mutual capacitance measurement of the plurality of mutual capacitance measurements is performed.

6. The method of claim 5, further comprising performing at least one of the mutual capacitance measurements, wherein the performing the at least one of the mutual capacitance measurements measuring a capacitance for each of a subset of intersections between the pairs of sensor electrodes of the plurality of sensor electrodes intersecting within a search window surrounding the predicted location.

7. The method of claim 1, wherein a spatial resolution of the self-capacitance measurements is different from a spatial resolution of the mutual capacitance measurements.

8. A method comprising:

resolving an initial location of a conductive object proximate to a touch-sensing surface by performing self-capacitance measurements of the touch-sensing surface in a self-capacitance mode, wherein the touch-sensing surface comprises rows of sensor electrodes and columns of sensor electrodes; and

determining a search window based on the resolved initial location;

in response to resolving the initial location of the conductive object, switching from operation in the self-capacitance mode to operation in a mutual capacitance mode;

in response to resolving the initial location of the conductive object, tracking a movement of the conductive object over the touch-sensing surface by determining a different resolved location of the conductive object for each of a plurality of consecutive mutual capacitance measurements of the search window while in the mutual capacitance mode, wherein performing each of the mutual capacitance measurements comprises measuring a capacitance between at least one pair of sensor electrodes of the touch-sensing surface;

identifying that the conductive object is located at an edge of the search window or outside of the search window based on the mutual capacitance measurements; and

when the conductive object is detected at the edge of the search window or outside of the search window, scanning at least one or more additional rows or columns of sensor electrodes that are adjacent to rows or columns within the search window without scanning an entire set of the rows and columns of sensor electrodes.

9. The method of claim 8, wherein performing the self-capacitance measurements comprises measuring a capacitance for each of a plurality of sensor electrodes of the touch-sensing surface, wherein the plurality of sensor electrodes comprise the row of sensor electrodes and the column of sensor electrodes.

10. The method of claim 9, wherein performing at least one of the mutual capacitance measurements comprises measuring a capacitance for each of a subset of intersections between the pairs of sensor electrodes of the plurality of sensor electrodes, wherein a number of intersections in the subset of intersections is less than a number of intersections of the plurality of sensor electrodes sensed during the self-capacitance measurements.

11. The method of claim 8, wherein an area of the touch-sensing surface sensed using each of the mutual capacitance measurements is less than an area of the touch-sensing surface sensed using the self-capacitance measurements.

12. The method of claim 8, further comprising, based on the first resolved location of the conductive object, calculating a predicted location for the conductive object corresponding to a time at which a first mutual capacitance measurement of the plurality of mutual capacitance measurements is performed.

13. The method of claim 12, wherein performing the first mutual capacitance measurement comprises measuring a capacitance for each of a subset of intersections between the pairs of sensor electrodes of the plurality of sensor electrodes intersecting within the search window, and wherein the search window surrounds the predicted location.

14. The method of claim 8, wherein determining the search window further comprises identifying an area surrounding a predicted location of the conductive object as the search window.

15. The method of claim 8, wherein a spatial resolution of the self-capacitance measurements is different from a spatial resolution of the mutual capacitance measurements.

16. A touch-sensing system, comprising:

a capacitive sensor array comprising a plurality of sensor electrodes;

a capacitance sensor configured to measure a self-capacitance of each of the plurality of sensor electrodes in a self-capacitance mode and to measure a mutual capacitance for each intersection between pairs of sensor electrodes of the plurality of sensor electrodes in a mutual capacitance mode; and

processing logic configured to, in response to determining a first resolved location of the conductive object using self-capacitance measurements of the plurality of sensor electrodes, switch from operation in the self-capacitance mode to operation in the mutual capacitance mode, and in response to determining the first resolved location of the conductive object using the self-capacitance measurements, track movement of the conductive object over the capacitive sensor array by determining a different resolved location of the conductive object for each of a plurality of consecutive mutual capacitance measurements of the pairs of the plurality of sensor electrodes of the capacitive sensor array while in the mutual capacitance mode, wherein performing each of the mutual capacitance measurements comprise comprises measuring a mutual capacitance between at least one pair of sensor electrodes of the capacitive sensor array, wherein the processing logic is further to;

measure first self-capacitances of a first set of the plurality of sensor electrodes disposed in a first axis of the touch-sensing surface; and

measure second self-capacitances of a second set of the plurality of sensor electrodes disposed in a second axis of the touch-sensing surface;

determine that the conductive object is no longer present proximate to the touch-sensing surface during the mutual capacitance mode;

in response to the conductive object is no longer being present during the mutual capacitance mode, switch from the operation in the mutual capacitance mode to the operation in the self-capacitance mode;

in response to the switching to the self-capacitance mode,

measure third self-capacitances of the first set of sensor electrodes to detect a second presence of the conductive object or a new conductive object proximate to the touch-sensing surface; and

measure fourth self-capacitances of the second set of sensor electrodes only when the second presence is detected in the measuring the third self-capacitances.

17. The touch-sensing system of claim 16, wherein a spatial resolution of the self-capacitance measurements is different from a spatial resolution of the mutual capacitance measurements.

18. The touch-sensing system of claim 16, wherein the capacitance sensor is further configured to perform at least one of the mutual capacitance measurements by measuring the mutual capacitance for each of a subset of intersections between the pairs of sensor electrodes of the plurality of sensor electrodes, wherein a number of intersections in the subset of intersections is less than a number of intersections of the plurality of sensor electrodes sensed during the self-capacitance measurements.

19. The touch-sensing system of claim 16, further comprising a touch-sensing surface, wherein the touch-sensing surface comprises the capacitive sensor array, and wherein an area of the touch-sensing surface sensed for each of the mutual capacitance measurements is less than an area of the touch-sensing surface sensed using the self-capacitance measurements.

20. The touch-sensing system of claim 16, wherein the processing logic is further configured to, based on the first resolved location of the conductive object, calculate a predicted location for the conductive object corresponding to a time at which the mutual capacitance measurements are performed, wherein performing the first mutual capacitance measurement comprises measuring a capacitance for each of a subset of intersections between the pairs of sensor electrodes of the plurality of sensor electrodes intersecting within a search window surrounding the predicted location.