Stylus tilt and orientation estimation from touch sensor panel images

• US 9,569,045 B2
• Filed: 05/21/2014
• Issued: 02/14/2017
• Est. Priority Date: 05/21/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Westerman, Wayne Carl
• Primary Examiner(s): Bibbins, Latanya
• Application Number:
  US14/284,316
• Publication Number:
  US 20150338949A1
• Time in Patent Office: 1,000 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures

Abstract

The detection of an orientation of a stylus relative to a touch sensitive surface is disclosed. In one example, a touch image of the stylus tip and the hand used to grasp the stylus can be captured by the touch sensor panel and analyzed to determine the stylus'"'"' orientation relative to the surface of the touch sensor panel. The analysis can include estimating the size of the user'"'"'s hand, determining the distance away from the user'"'"'s hand at which the stylus tip makes contact with the touch sensor panel, and determining an angle of tilt based on the estimated size of the user'"'"'s hand and the distance between the tip and the user'"'"'s hand.

Claims

1. A method for estimating an orientation of a stylus relative to a touch sensor panel, the method comprising:

acquiring a touch image from the touch sensor panel;

determining a location of a stylus tip from the acquired touch image;

determining a location of a hand grasping the stylus from the acquired touch image;

determining an angle between the location of the stylus tip and the location of the hand grasping the stylus;

determining a size of the hand grasping the stylus; and

estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip, the determined location of the hand grasping the stylus, the determined angle between the location of the stylus tip and the location of the hand grasping the stylus and the determined size of the hand grasping the stylus.

2. The method of claim 1, wherein determining a location of a hand grasping the stylus from the acquired touch image includes approximating a portion of the acquired touch image into one or more ellipses, the one or more ellipses representing the portion of the hand grasping the stylus that is in contact with the touch sensor panel.

3. The method of claim 2, wherein determining a location of a hand grasping the stylus from the acquired touch image further includes determining a major and minor axis for each of the one or more ellipses and one or more foci of the one or more ellipses.

4. The method of claim 3, wherein estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip and the determined location of the hand grasping the stylus includes determining a distance between the determined location of the stylus tip and the one or more foci of the one or more ellipses.

5. The method of claim 1, wherein estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip and the determined location of the hand grasping the stylus includes determining a distance between the determined location of the stylus tip and the determined location of the hand grasping the stylus.

6. The method of claim 5, wherein estimating the orientation of the stylus relative to the touch sensor panel further includes comparing the determined distance between the determined location of the stylus tip and the determined location of the hand grasping the stylus to a set of empirical data.

7. The method of claim 1, wherein the size of the hand grasping the stylus is determined based on a distance between foci of an ellipse representing the portion of the hand grasping the stylus.

8. The method of claim 1,

wherein the determined angle between the location of the stylus tip and the location of the hand grasping the stylus is measured with respect to a line parallel to a major axis or a minor axis of an ellipse representing the portion of the hand grasping the stylus.

9. A touch sensitive device configured to estimate an orientation of a stylus, the device comprising:

a touch sensor panel; and

a processor capable of;

acquiring a touch image from the touch sensor panel;

determining a location of a stylus tip from the acquired touch image;

determining a location of a hand grasping the stylus from the acquired touch image;

determining an angle between the location of the stylus tip and the location of the hand grasping the stylus;

determining a size of the hand grasping the stylus; and

estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip, the determined location of the hand grasping the stylus, the determined angle between the location of the stylus tip and the location of the hand grasping the stylus and the determined size of the hand grasping the stylus.

10. The touch sensitive device of claim 9, wherein determining a location of a hand grasping the stylus from the acquired touch image includes approximating a portion of the acquired touch image into one or more ellipses, the one or more ellipses representing the portion of the hand grasping the stylus that is in contact with the touch sensor panel.

11. The device of claim 10, wherein determining a location of a hand grasping the stylus from the acquired touch image further includes determining a major and minor axis for each of the one or more ellipses and one or more foci of the one or more ellipses.

12. The device of claim 11, wherein estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip and the determined location of the hand grasping the stylus includes determining a distance between the determined location of the stylus tip and the one or more foci of the one or more ellipses.

13. The device of claim 9, wherein estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip and the determined location of the hand grasping the stylus includes determining a distance between the determined location of the stylus tip and the determined location of the hand grasping the stylus.

14. The device of claim 13, wherein estimating the orientation of the stylus relative to the touch sensor panel further includes comparing the determined distance between the determined location of the stylus tip and the determined location of the hand grasping the stylus to a set of empirical data.

15. The device of claim 9, the processor further capable of:

determining the size of the hand grasping the stylus based on a distance between foci of an ellipse representing the portion of the hand grasping the stylus.

16. The device of claim 9,

wherein the determined angle between the location of the stylus tip and the location of the hand grasping the stylus is measured with respect to a line parallel to a major axis or a minor axis of an ellipse representing the portion of the hand grasping the stylus.

17. A non-transitory computer readable storage medium having stored thereon a set of instructions for estimating a tilt of a stylus in contact with a touch sensor panel, that when executed by a processor causes the processor to:

acquire a touch image from the touch sensor panel;

determine a location of a stylus tip from the acquired touch image;

determine a location of a hand grasping the stylus from the acquired touch image;

determine an angle between the location of the stylus tip and the location of the hand grasping the stylus;

determine a size of the hand grasping the stylus; and

estimate an orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip, the determined location of the hand grasping the stylus, the determined angle between the location of the stylus tip and the location of the hand grasping the stylus and the determined size of the hand grasping the stylus.

18. The non-transitory computer readable storage medium of claim 17, wherein determining a location of a hand grasping the stylus from the acquired touch image includes approximating a portion of the acquired touch image into one or more ellipses, the one or more ellipses representing the portion of the hand grasping the stylus that is in contact with the touch sensor panel.

19. The non-transitory computer readable storage medium of claim 18, wherein determining a location of a hand grasping the stylus from the acquired touch image further includes determining a major and minor axis for each of the one or more ellipses and one or more foci of the one or more ellipses.

20. The non-transitory computer readable storage medium of claim 19, wherein estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip and the determined location of the hand grasping the stylus includes determining a distance between the determined location of the stylus tip and the one or more foci of the one or more ellipses.

21. The non-transitory computer readable storage medium of claim 17, wherein estimating the orientation of the stylus relative to the touch sensor panel based on the determined location of the stylus tip and the determined location of the hand grasping the stylus includes determining a distance between the determined location of the stylus tip and the determined location of the hand grasping the stylus.

22. The non-transitory computer readable storage medium of claim 21, wherein estimating the orientation of the stylus relative to the touch sensor panel further includes comparing the determined distance between the determined location of the stylus tip and the determined location of the hand grasping the stylus to a set of empirical data.

23. The non-transitory computer readable storage medium of claim 17, the processor further caused to:

determine the size of the hand grasping the stylus based on a distance between foci of an ellipse representing the portion of the hand grasping the stylus.

24. The non-transitory computer readable storage medium of claim 17,

wherein the determined angle between the location of the stylus tip and the location of the hand grasping the stylus is measured with respect to a line parallel to a major axis or a minor axis of an ellipse representing the portion of the hand grasping the stylus.