TOUCH DETECTION USING MULTIPLE SIMULTANEOUS FREQUENCIES

• US 20140240287A1
• Filed: 05/05/2014
• Published: 08/28/2014
• Est. Priority Date: 06/13/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hotelling, Steve Porter, O'Connor, Sean Erik, Westerman, Wayne Carl, Krah, Christoph Horst
• Granted Patent: US 9,092,086 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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

The use of multiple stimulation frequencies and phases to generate an image of touch on a touch sensor panel is disclosed. Each of a plurality of sense channels can be coupled to a column in a touch sensor panel and can have multiple mixers. Each mixer in the sense channel can utilize a circuit capable generating a demodulation frequency of a particular frequency. At each of multiple steps, various phases of selected frequencies can be used to simultaneously stimulate the rows of the touch sensor panel, and the multiple mixers in each sense channel can be configured to demodulate the signal received from the column connected to each sense channel using the selected frequencies. After all steps have been completed, the demodulated signals from the multiple mixers can be used in calculations to determine an image of touch for the touch sensor panel at each frequency.

Claims

1. A method for obtaining a plurality of values used to generate one or more images of touch from touch sensor circuitry, comprising:

selecting, during a first frame, one or more first low noise frequencies;

simultaneously applying, during the first frame, a plurality of first stimulation signals to a plurality of drive lines of the touch sensor circuitry, wherein the plurality of first stimulation signals include signals having one or more first stimulation frequencies and multiple stimulation phases;

receiving, during a first frame, a first sense signal from each of a plurality of sense lines of the touch sensor circuitry into a different sense channel; and

demodulating the first sense signal with a plurality of first demodulation signals, wherein the plurality of first demodulation signals has one or more first demodulation frequencies, wherein the one or more first demodulation frequencies are based on at least one of the one or more first stimulation frequencies, and wherein the plurality of first demodulation signals has multiple demodulation phases that are based on the multiple first stimulation phases.

2. The method of claim 1, further comprising accumulating, during the first frame, the first sense signals demodulated with the plurality of first demodulation signals in each sense channel to generate a plurality of first values representing the accumulated demodulated first sense signals for each sense channel.

3. The method of claim 2, further comprising storing the plurality of first values for all sense channels.

4. The method of claim 1, further comprising:

selecting, during a second frame, one or more second low noise frequencies;

simultaneously applying, during the second frame, a plurality of second stimulation signals to the plurality of drive lines of the touch sensor circuitry, wherein the plurality of second stimulation signals include signals having one or more second stimulation frequencies and multiple stimulation phases;

receiving, during a second frame, a second sense signal from each of the plurality of sense lines of the touch sensor circuitry into a different sense channel; and

demodulating the second sense signal with a plurality of second demodulation signals, wherein the plurality of second demodulation signals has one or more second demodulation frequencies, wherein the one or more second demodulation frequencies are based on at least one of the one or more second stimulation frequencies, and wherein the plurality of second demodulation signals has multiple demodulation phases that are based on the multiple second stimulation phases.

5. The method of claim 4, further comprising accumulating, during the second frame, the second sense signals demodulated with the plurality of second demodulation signals in each sense channel to generate a plurality of second values representing the accumulated demodulated second sense signals for each sense channel.

6. The method of claim 5, further comprising storing the plurality of second values for all sense channels.

7. The method of claim 4, wherein the one or more first stimulation frequencies are different than the one or more second stimulation frequencies.

8. The method of claim 4, wherein the one or more first stimulation frequencies are selected from the one or more first low noise frequencies and the one or more second stimulation frequencies are selected from the one or more second low noise frequencies.

9. The method of claim 4, wherein determining the one or more first low noise frequencies comprises:

demodulating, during the first frame, a combined noise signal from the plurality of sense lines in an unstimulated touch sensor panel with in-phase (I) and quadrature (Q) components of a first plurality of frequencies;

accumulating, during the first frame, the I and Q components of the demodulated noise signal for each of the first plurality of frequencies;

calculating, during the first frame, a magnitude of the accumulated I and Q components of the demodulated noise signal for each of the first plurality of frequencies; and

determining, during the first frame, the one or more first low noise frequencies by selecting the frequencies whose generated magnitudes are smallest.

10. The method of claim 4, wherein determining the one or more second low noise frequencies comprises:

demodulating, during the second frame, a combined noise signal from the plurality of sense lines in an unstimulated touch sensor panel with in-phase (I) and quadrature (Q) components of a first plurality of frequencies;

accumulating, during the second frame, the I and Q components of the demodulated noise signal for each of the first plurality of frequencies;

calculating, during the second frame, a magnitude of the accumulated I and Q components of the demodulated noise signal for each of the first plurality of frequencies; and

determining, during the second frame, the one or more second low noise frequencies by selecting the frequencies whose generated magnitudes are smallest.

11. The method of claim 9, wherein determining one or more first low noise frequencies further comprises demodulating the combined noise signal with I and Q components of one or more different pluralities of frequencies, and accumulating the I and Q components of the demodulated noise signal for each of the one or more different plurality of frequencies.

12. The method of claim 10, wherein determining one or more second low noise frequencies further comprises demodulating the combined noise signal with I and Q components of one or more different pluralities of frequencies, and accumulating the I and Q components of the demodulated noise signal for each of the one or more different plurality of frequencies.

13. The method of claim 1, further comprising selecting and simultaneously applying multiple unique distributions of the plurality of first stimulation signals to the plurality of drive lines and storing multiple pluralities of first values after applying each of the multiple unique distributions during the first frame.

14. The method of claim 4, further comprising selecting and simultaneously applying multiple unique distributions of the plurality of second stimulation signals to the plurality of drive lines and storing multiple pluralities of second values after applying each of the multiple unique distributions during the first frame.

15. The method of claim 13, further comprising, for each of the plurality of sense lines, computing and storing a drive line result for each drive line and each of the one or more first stimulation frequencies using the stored multiple pluralities of first values.

16. The method of claim 14, further comprising, for each of the plurality of sense lines, computing and storing a drive line result for each drive line and each of the one or more second stimulation frequencies using the stored multiple pluralities of second values.

17. An apparatus for obtaining a plurality of values used to generate one or more images of touch, comprising:

touch sensor circuitry including a plurality of drive lines and a plurality of sense lines; and

an integrated circuit coupled to the touch sensor circuitry capable of;

selecting, during a first frame, one or more first low noise frequencies;

simultaneously applying, during the first frame, a plurality of first stimulation signals to the plurality of drive lines of the touch sensor circuitry, wherein the plurality of first stimulation signals include signals having one or more first stimulation frequencies and multiple stimulation phases;

receiving, during a first frame, a first sense signal from each of a plurality of sense lines of the touch sensor circuitry into a different sense channel; and

demodulating the first sense signal with a plurality of first demodulation signals, wherein the plurality of first demodulation signals has one or more first demodulation frequencies, wherein the one or more first demodulation frequencies are based on at least one of the one or more first stimulation frequencies, and wherein the plurality of first demodulation signals has multiple demodulation phases that are based on the multiple first stimulation phases.

18. The apparatus of claim 17, the integrated circuit further capable of:

accumulating, during the first frame, the first sense signals demodulated with the plurality of first demodulation signals in each sense channel to generate a plurality of first values representing the accumulated demodulated first sense signals for each sense channel.

19. The apparatus of claim 18, the integrated circuit further capable of:

storing the plurality of first values for all sense channels.

20. The apparatus of claim 17, the integrated circuit further capable of:

selecting, during a second frame, one or more second low noise frequencies;

simultaneously applying, during the second frame, a plurality of second stimulation signals to the plurality of drive lines of the touch sensor circuitry, wherein the plurality of second stimulation signals include signals having one or more second stimulation frequencies and multiple stimulation phases;

receiving, during a second frame, a second sense signal from each of the plurality of sense lines of the touch sensor circuitry into a different sense channel; and

demodulating the second sense signal with a plurality of second demodulation signals, wherein the plurality of second demodulation signals has one or more second demodulation frequencies, wherein the one or more second demodulation frequencies are based on at least one of the one or more second stimulation frequencies, and wherein the plurality of second demodulation signals has multiple demodulation phases that are based on the multiple second stimulation phases.

21. The apparatus of claim 20, the integrated circuit further capable of:

accumulating, during the second frame, the second sense signals demodulated with the plurality of second demodulation signals in each sense channel to generate a plurality of second values representing the accumulated demodulated second sense signals for each sense channel.

22. The apparatus of claim 21, the integrated circuit further capable of:

storing the plurality of second values for all sense channels.

23. The apparatus of claim 20, wherein the one or more first stimulation frequencies are different than the one or more second stimulation frequencies.

24. The apparatus of claim 20, wherein the one or more first stimulation frequencies are selected from the one or more first low noise frequencies and the one or more second stimulation frequencies are selected from the one or more second low noise frequencies.

25. The apparatus of claim 20, wherein determining the one or more first low noise frequencies comprises:

demodulating, during the first frame, a combined noise signal from the plurality of sense lines in an unstimulated touch sensor panel with in-phase (I) and quadrature (Q) components of a first plurality of frequencies;

accumulating, during the first frame, the I and Q components of the demodulated noise signal for each of the first plurality of frequencies;

calculating, during the first frame, a magnitude of the accumulated I and Q components of the demodulated noise signal for each of the first plurality of frequencies; and

determining, during the first frame, the one or more first low noise frequencies by selecting the frequencies whose generated magnitudes are smallest.

26. The apparatus of claim 20, wherein determining the one or more second low noise frequencies comprises:

demodulating, during the second frame, a combined noise signal from the plurality of sense lines in an unstimulated touch sensor panel with in-phase (I) and quadrature (Q) components of a first plurality of frequencies;

accumulating, during the second frame, the I and Q components of the demodulated noise signal for each of the first plurality of frequencies;

calculating, during the second frame, a magnitude of the accumulated I and Q components of the demodulated noise signal for each of the first plurality of frequencies; and

determining, during the second frame, the one or more second low noise frequencies by selecting the frequencies whose generated magnitudes are smallest.

27. The apparatus of claim 25, wherein determining one or more first low noise frequencies further comprises demodulating the combined noise signal with I and Q components of one or more different pluralities of frequencies, and accumulating the I and Q components of the demodulated noise signal for each of the one or more different plurality of frequencies.

28. The apparatus of claim 26 wherein determining one or more second low noise frequencies further comprises demodulating the combined noise signal with I and Q components of one or more different pluralities of frequencies, and accumulating the I and Q components of the demodulated noise signal for each of the one or more different plurality of frequencies.

29. The apparatus of claim 17, the integrated circuit further capable of:

selecting and simultaneously applying multiple unique distributions of the plurality of first stimulation signals to the plurality of drive lines and storing multiple pluralities of first values after applying each of the multiple unique distributions during the first frame.

30. The apparatus of claim 20, the integrated circuit further capable of:

selecting and simultaneously applying multiple unique distributions of the plurality of second stimulation signals to the plurality of drive lines and storing multiple pluralities of second values after applying each of the multiple unique distributions during the first frame.

31. The apparatus of claim 29, the integrated circuit further capable of:

for each of the plurality of sense lines, computing and storing a drive line result for each drive line and each of the one or more first stimulation frequencies using the stored multiple pluralities of first values.

32. The apparatus of claim 30, the integrated circuit further capable of:

for each of the plurality of sense lines, computing and storing a drive line result for each drive line and each of the one or more second stimulation frequencies using the stored multiple pluralities of second values.