Touch tracking on a touch sensitive interface

• US 9,134,848 B2
• Filed: 06/03/2009
• Issued: 09/15/2015
• Est. Priority Date: 06/03/2009
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Ng, Hon Siong
• Primary Examiner(s): Okebato, Sahlu
• Application Number:
  US12/477,745
• Publication Number:
  US 20100309139A1
• Time in Patent Office: 2,295 Days
• Field of Search: 345/173, 382/103, 382/107
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04186 Touch location disambiguation

Abstract

A method tracks a plurality of touch points across successive frames of a touch sensitive input device to determine a trajectory. Each touch point on a frame of a touch sensitive input device is correlated with another distinct touch point on a subsequent frame of the same touch sensitive input device. The correlation is based on examining in the subsequent frame an area surrounding each touch point on the previous frame. Touch points identified within this search area are prioritized based on a projected trajectory through the prior touch point based on historical data.

Claims

1. A method, comprising:

receiving input values that are registered by touch locations of a touch sensitive input device;

generating a plurality of frames from the received input values, each frame including one or more touch points;

correlating each touch point on a first frame of the plurality of frames with a distinct touch point on a subsequent frame of the plurality of frames, wherein correlating comprises isolating the at least one distinct touch point by a search distance associated with each touch point on the first frame and a trajectory associated with each touch point on the first frame, performing a trajectory cost function for each of the distinct touch points in the subsequent frame and associating one of the distinct touch points in the subsequent frame having a minimal cost function with a first touch point in the first frame to extend the trajectory, wherein the search distance has a magnitude for each of the distinct touch points on the subsequent frame that is based on a differential positional change of each touch point between the first frame and a prior frame of the plurality of frames; and

generating an instruction for a computer coupled to the touch sensitive input device to perform a function based on the correlated touch points.

2. The method of claim 1 wherein the search distance surrounding each touch point on the first frame for capturing the distinct touch point on the subsequent frame is independently determined.

3. The method of claim 1 wherein touch points identified on the subsequent frame outside of the search distance of any touch point on the first frame are designated as new touch points.

4. The method of claim 1 wherein the trajectory for each touch point on the first frame is based on projecting an association between the touch point on the first frame and a touch point on a prior frame.

5. The method of claim 1 wherein responsive to more than one touch point on the subsequent frame being within the search distance associated with each touch point on the first frame, identifying which of the more than one touch point is more closely aligned with the trajectory associated with each touch point on the first frame.

6. The method of claim 5 further comprising selecting the identified more than one touch point as the distinct touch point on the subsequent frame.

7. The method of claim 1 wherein a historical record of each touch point for each frame is stored.

8. A non-transitory computer-readable storage medium tangibly embodying a program of instructions executable by a machine wherein said program of instructions comprises a plurality of program codes for tracking a plurality of touch points across frames of a touch sensitive input device, wherein the plurality of touch points are input values corresponding touch locations sensed at the touch sensitive input device and wherein the plurality of touch points are used to generate an instruction for a computer coupled to the touch sensitive input device to perform a function, said program of instructions comprising:

program code for correlating each touch point on a first frame of the plurality of frames with a distinct touch point on a subsequent frame of the plurality of frames, wherein correlating comprises isolating the at least one distinct touch point by a search distance associated with each touch point on the first frame and a trajectory associated with each touch point on the first frame, and performing a trajectory cost function for each of the distinct touch points in the subsequent frame and associating one of the distinct touch points in the subsequent frame having a minimal cost function with a first touch point in the first frame to extend the trajectory, wherein the search distance for the distinct touch points on the subsequent frame in the program code has a magnitude based on a differential positional change of each touch point between the first frame and a prior frame of the plurality of frames.

9. The computer-readable storage medium of claim 8 wherein the search distance surrounding each touch point on the first frame for capturing the distinct touch point on the subsequent frame in the program code for correlating is independently determined.

10. The computer-readable storage medium of claim 9 wherein touch points identified on the subsequent frame outside of the search distance of any touch point on the first frame in the program code for correlating are designated as new touch points.

11. The computer-readable storage medium of claim 8 wherein the trajectory for each touch point on the first frame in the program code for correlating is based on projecting an association between the touch point on the first frame and a touch point on a prior frame.

12. The computer-readable storage medium of claim 8 wherein responsive to more than one touch point on the subsequent frame being within the search distance associated with each touch point on the first frame, further comprising program code for identifying which of the more than one touch point is more closely aligned with the trajectory associated with each touch point on the first frame.

13. A computer system for tracking a plurality of touch points across frames of a touch sensitive input device, the computer system comprising:

the touch sensitive input device configured to receive input values that are registered by touch locations of the plurality of touch points;

a machine capable of executing instructions embodied as software; and

a plurality of software portions, wherein one of said software portions is operable to correlate each touch point on a first frame of the plurality of frames with a distinct touch point on a subsequent frame of the plurality of frames, wherein correlating comprises isolating the at least one distinct touch point by a search distance associated with each touch point on the first frame and a trajectory associated with each touch point on the first frame, and wherein the search distance for the at least one distinct touch point on the subsequent frame in the program code has a magnitude based on a differential positional change of each touch point between the first frame and a prior frame.

14. The computer system of claim 13 wherein the search distance surrounding each touch point on the first frame for capturing the distinct touch point on the subsequent frame is independently determined.

15. The computer system of claim 14 wherein touch points identified on the subsequent frame outside of the search distance of any touch point on the first frame are designated as new touch points.

16. The computer system of claim 13 wherein the trajectory for each touch point on the first frame is based on projecting an association between the touch point on the first frame and a touch point on a prior frame.

17. The computer system of claim 13 wherein responsive to more than one touch point on the subsequent frame being within the search distance associated with each touch point on the first frame, identifying which of the more than one touch point is more closely aligned with the trajectory associated with each touch point on the first frame.