STYLUS TILT TRACKING WITH A DIGITIZER

• US 20150123923A1
• Filed: 11/05/2014
• Published: 05/07/2015
• Est. Priority Date: 11/05/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: N-Trig Ltd (Microsoft Corporation)
• Inventors: STERN, Yuval
• Granted Patent: US 9,477,330 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A method for detecting orientation of a stylus with respect to a digitizer sensing surface includes detecting a signal emitted by a stylus at a plurality of coordinates on a digitizer sensing surface, determining coordinate of a writing tip of the stylus, defining at least one feature characterizing an asymmetrical spread of the stylus signal on the digitizer sensing surface with respect to the writing tip coordinate, and characterizing an orientation of the stylus responsive to the characterization of the asymmetrical spread.

Claims

1. A method for detecting orientation of a stylus with respect to a digitizer sensing surface, the method comprising:

detecting a signal emitted by a stylus at a plurality of coordinates on a digitizer sensing surface;

determining coordinate of a writing tip of the stylus;

defining at least one feature characterizing an asymmetrical spread of the stylus signal on the digitizer sensing surface with respect to the writing tip coordinate; and

characterizing an orientation of the stylus responsive to the characterization of the asymmetrical spread.

2. The method according to claim 1, wherein the at least one feature is a gradient of a decaying function defined to characterize decay of amplitude from the coordinate of a writing tip as a function of distance from the coordinate of the writing tip.

3. The method according to claim 1, wherein the at least one feature is asymmetry in rate of decay from opposite sides of the coordinate of a writing tip.

4. The method according to claim 1, wherein the at least one feature includes a first rate of a decay of amplitude on one side of the writing tip coordinate along one axis of the digitizer sensor compared to a second rate of a decay of amplitude on an opposite side of the writing tip coordinate along the one axis of the digitizer sensor.

5. The method according to claim 4, wherein the at least one feature includes a third rate of a decay of amplitude on one side of the writing tip coordinate along a second axis of the digitizer sensor compared to a third rate of a decay of amplitude on an opposite side of the writing tip coordinate along that second axis of the digitizer sensor.

6. The method according claim 1, comprising correcting the writing tip coordinate determined, responsive to the orientation of the stylus as characterized.

7. The method according to claim 1, wherein characterizing an orientation of the stylus includes determining tilt angle of the stylus toward the digitizer sensing surface.

8. The method according to claim 1, wherein characterizing an orientation of the stylus includes determining a direction of a tilt of the stylus.

9. The method according to claim 1, determining the writing tip location is determined from an amplitude pattern obtained from the spread of the stylus signal on the digitizer sensing surface.

10. The method according to claim 9, wherein the writing tip coordinate is defined as coordinate at which amplitude of the detected stylus signal is estimated to have a peak.

11. The method according to claim 9 comprising defining an envelope over the amplitude pattern obtained from the spread of the stylus signal on the digitizer sensing surface;

and defining the writing tip coordinate at a location of a peak of the envelope.

12. The method according to claim 9 comprising defining a pair of decay functions that characterize decays of amplitude on either side of an estimated area of a peak and defining the writing tip coordinate at a location at which the pair of decay functions intersect.

13. The method according to claim 1, wherein the orientation of the stylus is reported to a host associated with the digitizer sensor.

14. A method for detecting orientation of a stylus with respect to a digitizer sensing surface, the method comprising:

tracking orientation of a digitizer sensing surface in three dimensions;

tracking orientation of a stylus interacting with the digitizer sensing surface in three dimensions, wherein the orientation of the digitizer sensing surface is tracked concurrently with tracking of the orientation of the stylus; and

comparing the orientation of the digitizer sensing surface with the orientation of the stylus; and

detecting an orientation of the stylus with respect to the digitizer sensing surface responsive to the comparing.

15. The method according to claim 14, wherein the orientation of digitizer sensing surface is tracked with an accelerometer is rigidly connected to the digitizer sensing surface.

16. The method according to claim 14, wherein the orientation of stylus is tracked with an accelerometer is positioned on the stylus.