CONTACT SENSITIVE DEVICE FOR DETECTING TEMPORALLY OVERLAPPING TRACES

• US 20110063228A1
• Filed: 09/11/2009
• Published: 03/17/2011
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Suljic, Damir, St. Pierre, Richard L.
• Granted Patent: US 8,325,160 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

Systems and methods for detecting temporally overlapping trace events on a touch sensitive device.

Claims

1. A touch sensitive device comprising:

a substrate capable of supporting bending waves having a first surface, a portion of the first surface defining a touch sensitive area;

a plurality of sensors coupled to the touch sensitive surface and configured to sense bending waves propagating through the substrate and provide electronic signals representative of the bending waves; and

,

electronics communicatively coupled to the plurality of sensors and configured to receive electronic signals from the sensors and based on these signals, calculate constituent coordinates of at least first and second traces made by at least a first and second objects dragged across portions of the touch sensitive area in a temporally overlapping manner.

2. The touch sensitive device of claim 1, further comprising:

an electronic display panel coupled the substrate, and wherein the substrate is transparent and overlaid upon the display such to define a touch sensitive display.

3. The touch sensitive device of claim 1, wherein the sensors are piezoelectric transducers.

4. The touch sensitive device of claim 1, wherein at least one of the first or second objects is a finger.

5. The touch sensitive device of claim 1, wherein at least on of the first or second objects is a stylus.

6. The touch sensitive device of claim 1, wherein the substrate is glass.

7. The touch sensitive device of claim 1, wherein the electronics are further communicatively coupled to a computer system, and the electronics are further configured to provide signals indicative of the constituent coordinates of the traces to the computer system.

8. The touch sensitive device of claim 1, wherein calculate comprises repeatedly:

(a) determining a first and a second candidate coordinates defining possible positions of the first and second objects at a point in time;

(b) associating the first and second candidate coordinates with either the first or second traces;

(c) validating the candidate coordinates; and

,

(d) letting the validated candidate coordinates be constituent coordinates of the respective first or second traces.

9. The touch sensitive device of claim 8, further comprising:

providing signals indicative of the constituent coordinate of the first and second traces to a computer.

10. The touch sensitive device of claim 1, wherein calculate constituent coordinates comprises:

calculating candidate coordinates using the electronic signals received from the sensors;

validating the candidate coordinates;

computing constituent coordinates, using the validated candidate coordinates, for either the first or second trace.

11. The touch sensitive device of claim 10, wherein validating the candidate coordinates comprises determining whether the candidate coordinate is reasonable given the velocity and direction of the trace.

12. The touch sensitive device of claim 10, wherein validating the candidate coordinates comprises using an algorithm to determine allowable next constituent coordinates of a trace, then comparing the candidate coordinate to the these allowable next coordinates, and validating the candidate coordinate if there is a match.

13. The touch sensitive device of claim 12, wherein the algorithm uses a predictive filter.

14. The touch sensitive device of claim 13, wherein the predictive filter is a Kalman filter.

15. The touch sensitive device of claim 13, wherein the validated candidate coordinate becomes a constituent coordinate of the trace to which it is determined to be an allowable next coordinate.

16. The touch sensitive device of claim 13, wherein the validated candidate coordinate becomes a constituent coordinate of the trace to which it is closest.

17. A method for resolving constituent coordinates of a plurality of traces (n) made by dragging objects across the touch sensitive surface of a touch sensitive device in a temporally overlapping manner, comprising:

receiving from the sensors bending wave information indicative of bending of the substrate in response to n temporally overlapping trace events;

calculating from the bending wave information candidate coordinates representative of the coordinates of trace objects at points in time during the plurality of traces; and

associating the candidate coordinates with a particular one of the n traces.

18. The method of claim 17, wherein associating the candidate coordinates with a trace event comprises:

using a predictive filter to validate the candidate coordinates, and then associating valid candidate coordinates with particular ones of the n traces.

19. The method of claim 18, further comprising:

and not associating invalid candidate coordinates with any of the n traces.

20. The method of claim 18, wherein associating each of the candidate coordinates with a trace event further comprises:

after validating the candidate coordinates, associating valid candidate coordinates with particular ones of the n traces to which the valid candidate coordinates are respectively closest to.

21. The method of claim 18, wherein the predictive filter is a stochastic estimation filter.

22. The method of claim 21, wherein the stochastic estimation filter is a Kalman filter.

23. The method of claim 18, further comprising:

providing information indicative of the n traces to a computer.

24. The method of claim 23, further comprising:

updating a display device communicatively coupled to the computer with information indicative of the n traces.

25. The method of claim 17, wherein associating the candidate coordinates with a trace event comprises associating the candidate coordinate with the trace event to which it is closest.

26. The method of claim 17, further comprising, before associating the candidate coordinates with a particular one of the n traces, validating the candidate coordinates.

27. The method of claim 26, wherein validating the candidate coordinates comprises:

using a predictive filter to determine whether the candidate coordinates are consistent with the direction and velocity of any of the n traces.

28. The method of claim 26, wherein validating the candidate coordinates comprises:

determining whether the distance from a candidate coordinate and the last known coordinate of one of the n trace events exceeds a threshold value.

29. The method of claim 28, wherein the threshold value is particular to each of the n trace events and is dynamically updated as a function of the velocity and direction of the particular n trace events.