STYLUS DETECTION AND DEMODULATION

• US 20140267075A1
• Filed: 03/14/2013
• Published: 09/18/2014
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: SHAHPARNIA, Shahrooz, Elias, John Greer
• Granted Patent: US 10,048,775 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/041661 using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A touch input device configured to detect stylus signals generated by an external stylus is provided. The touch input device includes a plurality of stylus signal detectors that can receive the stylus signal and estimate the start and end time of the stylus signal in order to facilitate windowed demodulation of signal. The touch input device also includes circuitry to determine which of the plurality of detectors is most likely to have received the stylus signal and based on that determination can demodulate the signal and extract data embedded within the stylus signal.

Claims

1. A method of detecting stylus signals generated by an external stylus on a touch input device, the method comprising:

configuring the touch input device to receive a stylus signal;

receiving the stylus signal at a plurality of stylus signal detectors;

determining which of the plurality of stylus signal detectors has a greatest likelihood of having received the stylus signal; and

demodulating the received stylus signal based on one or more metrics generated by the determined stylus signal detector.

2. The method of claim 1, wherein configuring the touch input device to receive a stylus signal includes configuring a plurality of drive lines and a plurality of sense lines configured for receiving touch inputs to additionally receive a stylus signal.

3. The method of claim 2, wherein configuring the plurality of sense lines to receive a stylus signal includes coupling each sense line of the plurality of sense lines to a stylus signal detector.

4. The method of claim 1, wherein the one or more metrics can include an estimated start time of the detected stylus signal, an estimated end time of the stylus signal, and an estimated signal strength of the detected stylus signal.

5. The method of claim 4, wherein determining which of the plurality of stylus signal detectors has the greatest likelihood of having received the stylus signal includes comparing the estimated signal strengths of the plurality of detectors and determining which detector of the plurality of detectors has the greatest estimated signal strength.

6. The method of claim 4, wherein demodulating the received stylus signal based on the one or more metrics generated by the determined stylus detector includes using the estimated start time of the detected stylus signal and the estimated end time of the stylus signal to facilitate a windowed demodulation of the stylus signal.

7. The method of claim 1, further comprising organizing the demodulated stylus signal into a frame of data, wherein the frame of data is synchronized in time to the generation of the stylus signal by an external stylus.

8. The method of claim 1, further comprising extracting a plurality of data from the demodulated stylus signal.

9. An apparatus for detecting stylus signals generated by an external stylus on a touch input device, the apparatus comprising:

a plurality of electrodes capable of operating as touch hardware during a touch operation mode and operating as stylus detection hardware during a stylus detection mode;

a plurality of stylus signal detectors coupled to the plurality of electrodes during a stylus detection mode, each stylus detector capable of receiving a stylus signal and generating one or more metrics pertaining to the detected stylus signal;

an arbiter capable of determining which of the plurality of stylus signal detectors has the greatest likelihood of having received the stylus signal; and

a demodulator configured to demodulate the stylus signal based on the one or more metrics generated by the stylus detector determined to have the greatest likelihood of having received the stylus signal.

10. The apparatus of claim 9, further including a processor capable of configuring the input device to alternate between a touch detection mode and a stylus detection mode, wherein configuring the input device to operate in a stylus detection mode includes configuring a plurality of drive lines and a plurality of sense lines configured to receive a touch input to receive a stylus signal.

11. The apparatus of claim 10, further comprising switching hardware configured to couple each sense line of the plurality of sense lines to a stylus signal detector.

12. The apparatus of claim 9, wherein the one or more metrics generated by the plurality of stylus detectors can include an estimated start time of the detected stylus signal, an estimated end time of the stylus signal, and an estimated signal strength of the detected stylus signal.

13. The apparatus of claim 12, wherein the arbiter determines which of the plurality of detectors has the greatest likelihood of having received the stylus signal by comparing the estimated signal strengths of the plurality of detectors and determining which detector of the plurality of detectors has the greatest estimated signal strength.

14. The apparatus of claim 12, wherein the demodulator can use the estimated start time of the detected stylus signal and the estimated end time of the stylus signal to facilitate a windowed demodulation of the stylus signal.

15. The apparatus of claim 9, further comprising a frame synchronizer configured to organize the demodulated stylus signal into a frame of data, wherein the frame of data is synchronized in time to the generation of the stylus signal by an external stylus.

16. The apparatus of claim 9, further comprising a data extraction unit configured to extract a plurality of data from the demodulated stylus signal.

17. A non-transitory computer readable storage medium having stored thereon a set of instructions for detecting a demodulating a stylus signal generated by an external stylus, that when executed by a processor causes the processor to:

configure the touch input device to receive a stylus signal;

receive the stylus signal on the touch sensor panel;

determine which of the plurality of detectors has the greatest likelihood of having received the stylus signal; and

demodulate the received stylus signal based on one or more metrics generated by the stylus detector determined to have the greatest likelihood of having received the stylus signal.

18. The non-transitory computer readable storage medium of claim 17, wherein configuring the touch input device to receive a stylus signal includes configuring a plurality of drive lines and a plurality of sense lines configured for receiving touch inputs to additionally receive a stylus signal.

19. The non-transitory computer readable storage medium of claim 18, wherein configuring the plurality of sense lines to receive a stylus signal includes coupling each sense line of the plurality of sense lines to a stylus signal detector.

20. The non-transitory computer readable storage medium of claim 17, wherein the one or more metrics can include an estimated start time of the detected stylus signal, an estimated end time of the stylus signal, and an estimated signal strength of the detected stylus signal.

21. The non-transitory computer readable storage medium of claim 20, wherein determining which of the plurality of stylus signal detectors has the greatest likelihood of having received the stylus signal includes comparing the estimated signal strengths of the plurality of detectors and determining which detector of the plurality of detectors has the greatest estimated signal strength.

22. The non-transitory computer readable storage medium of claim 20, wherein demodulating the received stylus signal based on the one or more metrics generated by the determined stylus detector includes using the estimated start time of the detected stylus signal and the estimated end time of the stylus signal to facilitate a windowed demodulation of the stylus signal.

23. The non-transitory computer readable storage medium of claim 17, wherein the processor is further caused to organize the demodulated stylus signal into a frame of data, wherein the frame of data is synchronized in time to the generation of the stylus signal by an external stylus.

24. The non-transitory computer readable storage medium of claim 17, wherein the processor is further caused to extract a plurality of data from the demodulated signal.