Methods for Detecting and Tracking Touch Objects

1 . In a touch sensitive user interface environment have a series of possible touch points on an activation surface, with the monitoring of the touch points being achieved by sensing activation values at a plurality of positions around the periphery of the activation surface, a method of determining where at least one touch point has been activated on the surface, the method including the steps of:

(a) determining at least one intensity variation in the activation values: and

(b) utilizing a gradient measure of the sides of the at least one intensity variation to determine the location of at least one touch point on the activation surface.

2 . The method as claimed in claim 1 wherein the number of touch points is at least two and the location of the touch points is determined by reading multiple intensity variations along the periphery of the activation surface and correlating the multiple points to determine likely touch points.

3 . The method as claimed in claim 1 wherein adjacent opposed gradient measures of at least one intensity variation are utilized to disambiguate multiple touch point.

4 . The method as claimed in claim 1 wherein the method further includes the steps of:

continuously monitoring the time evolution of the intensity variations in the activation values; and

utilizing the time evolution in disambiguating multiple touch points.

5 . The method as claimed in claim 4 wherein a first identified intensity variation is utilized in determining the location of a first touch point and a second identified intensity variation is utilized in determining the location of a second touch point.

6 . The method as claimed in claim 2 wherein said activation surface includes a projected series of icons thereon and said disambiguation favours touch point locations corresponding to the icon positions.

7 . The method as claimed in claim 1 wherein

the dimensions of the intensity variations are utilized in determining the location of the at least one touch point.

8 . The method as claimed in claim 1 wherein:

recorded shadow diffraction characteristics of an object are utilized in disambiguating possible touch points.

9 . The method as claimed in claim 8 wherein:

the sharpness of the shadow diffraction characteristics are associated with the distance of the object from the periphery of the activation area.

10 . The method as claimed in claim 1 wherein disambiguation of possible touch points is achieved by monitoring the time evolution profile of the intensity variations and projecting future locations of each touch point.

11 . A method of determining the location of one or more touch points on a touch sensitive user interface environment having a series of possible touch points on an activation surface, with the monitoring of the touch points being achieved by activation values at a plurality of positions around the periphery of the activation surface, said method including the step of:

(a) tracking the edge profiles of activation values around the touch points over time.

12 . The method as claimed in claim 11 wherein, when an ambiguity occurs between multiple touch points, characteristics of the edge profiles are utilized to determine the expected location of touch points.

13 . The method as claimed in claim 12 wherein the characteristics include one or more gradients of each edge profile.

14 . The method as claimed in claim 12 wherein the characteristics include the width between adjacent edges in each edge profile.

15 . (canceled)