METHOD AND APPARATUS FOR DETECTING SIMULTANEOUS TOUCH EVENTS ON A BENDING-WAVE TOUCHSCREEN

• US 20110074544A1
• Filed: 09/29/2009
• Published: 03/31/2011
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: D'Souza, Henry M.
• Granted Patent: US 9,696,856 B2
• Time in Patent Office: Days
• US Class Current: 340/5.83
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0433 in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member

Abstract

A method of detecting touch events on a touch panel includes identifying sets of coordinate locations based on at least one signal from at least one sensor. The at least one signal is responsive to at least one touch event, and the coordinate locations represent matches with respect to template fingerprints. Consecutive ones of the sets of coordinate locations are compared based on a first distance threshold to form streams of spatially continuous coordinate locations that satisfy the first distance threshold. A touch event is identified corresponding to one of the streams of spatially continuous coordinate locations, the stream having a minimum number of spatially continuous coordinate locations.

Claims

1. A method of detecting touch events on a touch panel, comprising:

identifying sets of coordinate locations based on at least one signal from at least one sensor, the at least one signal being responsive to at least one touch event, the coordinate locations representing matches with respect to template fingerprints;

comparing consecutive ones of the sets of coordinate locations based on a first distance threshold to form streams of spatially continuous coordinate locations that satisfy the first distance threshold; and

identifying a touch event corresponding to one of the streams of spatially continuous coordinate locations, the stream having a minimum number of spatially continuous coordinate locations.

2. The method of claim 1, wherein a primary touch is identified based on a best match from within an initial set of coordinate locations, the touch event being identified subsequent to the primary touch, the touch event and the primary touch being simultaneous.

3. The method of claim 1, wherein the identifying the sets of coordinate locations further comprises:

identifying a best match from within one of the sets of coordinate locations, the best match having a highest degree of correlation with one of the template fingerprints;

eliminating the coordinate locations that are within a second distance threshold of the best match; and

identifying additional coordinate locations based on the at least one signal.

4. The method of claim 1, wherein the sets of coordinate locations are identified based on at least two signals from at least two sensors.

5. The method of claim 1, further comprising eliminating a stream when spatially continuous coordinate locations from a predetermined number of consecutive sets of coordinate locations have not been added to the stream.

6. The method of claim 1, wherein each of the coordinate locations has a score based on a degree of correlation with one of the template fingerprints, the method further comprising:

identifying a primary touch based on a highest degree of correlation from within a set of coordinate locations;

calculating an average score for the primary touch by averaging the scores associated with each of the coordinate locations in the stream associated with the primary touch; and

calculating an average score for the stream that comprises the minimum number of consecutive coordinate locations, the touch event being further identified based on a relationship between the average score for the primary touch and the average score for the stream.

7. The method of claim 1, further comprising detecting at least two simultaneous touch events on the touch panel.

8. The method of claim 1, further comprising identifying new coordinate locations of the touch event based on a set of coordinate locations identified after the touch event is identified, the new coordinate locations being proximate to the touch event.

9. The method of claim 1, wherein the minimum number of spatially continuous coordinate locations is at least three.

10. A touch system, comprising:

a touch panel;

at least one sensor to obtain signals associated with at least one touch event on the touch panel; and

a processor module configured to identify sets of coordinate locations based on the signals obtained over time, the coordinate locations representing matches with respect to template fingerprints, the processor module comparing consecutive ones of the sets of coordinate locations based on a distance threshold to form streams of spatially continuous coordinate locations that satisfy the distance threshold, the processor module identifying at least one touch event when one of the streams of spatially continuous coordinate locations has a minimum number of spatially continuous coordinate locations.

11. The touch system of claim 10, wherein the at least one sensor further comprises at least two sensors to obtain signals associated with at least two simultaneous touch events.

12. The touch system of claim 10, wherein the at least one sensor further comprises at least two sensors, the processor module further configured to construct a live fingerprint based on the signals obtained by the at least two sensors, the live fingerprint and the template fingerprints being based on at least one of an amplitude magnitude ratio and a phase difference.

13. The touch system of claim 10, the processor module being further configured to identify a primary touch based on a single frame of data comprising the signals, the primary touch being identified when only one of the coordinate locations has a degree of correlation with respect to the template fingerprints that satisfies a score threshold.

14. The touch system of claim 10, wherein the processor module is further configured to discard the coordinate locations that are within a predetermined distance of the at least one touch event.

15. A method for detecting at least two simultaneous touch events on a touch panel, comprising:

detecting at least one signal from at least one sensor;

constructing at least two live fingerprints based on the at least one signal;

identifying a set of best matches for each of the at least two live fingerprints based on a comparison of the at least two live fingerprints to template fingerprints; and

identifying simultaneous touch events when at least two of the best matches associated with one of the live fingerprints satisfy redundant validation criteria with respect to at least two of the best matches associated with the other live fingerprint.

16. The method of claim 15, wherein the detecting further comprises detecting at least three signals from at least three sensors.

17. The method of claim 15, wherein the redundant validation criteria is a distance threshold.

18. The method of claim 15, wherein the best matches comprise the template fingerprints that have a highest degree of correlation with the at least two live fingerprints, the method further comprising determining a score for each of the best matches based on the degree of correlation, the simultaneous touch events being further identified based on a comparison of the scores.

19. The method of claim 15, wherein the best matches comprise the template fingerprints that have a highest degree of correlation with the at least two live fingerprints, the method further comprising:

determining a score for each of the best matches based on the degree of correlation;

calculating a score ratio between a first best match associated with one of the live fingerprints and a second best match associated with the other live fingerprint, the first and second best matches satisfying the redundant validation criteria; and

rejecting the first and second best matches when the score ratio does not meet a threshold criteria.

20. The method of claim 15, further comprising identifying a single touch event when only one of the best matches associated with one of the live fingerprints satisfies the redundant validation criteria with respect to only one of the best matches associated with the other live fingerprint.