Automatic low noise frequency selection

• US 10,139,890 B2
• Filed: 05/18/2015
• Issued: 11/27/2018
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Wilson, Thomas James, Krah, Christoph H.
• Primary Examiner(s): Khoo, Stacy
• Application Number:
  US14/715,351
• Publication Number:
  US 20150261285A1
• Time in Patent Office: 1,289 Days
• Field of Search: 345173-178, 178 1801- 1809
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• 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 3/044 by capacitive means
• 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
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data

Abstract

Automatic low noise frequency selection for a touch sensitive device is disclosed. A low noise stimulation frequency can be automatically selected by device logic without intervention of the device processor to stimulate the device to sense a touch event at the device. The device logic can automatically select a set of low noise frequencies from among various frequencies based on the amount of noise introduced by the device at the various frequencies, where the frequencies with the lower noise amounts can be selected. The device logic can also automatically select a low noise frequency from among the selected set as the low noise stimulation frequency. The device logic can be implemented partially or entirely in hardware.

Claims

1. A touch sensitive device comprising:

a touch sensor panel;

at least one sense channel coupled to the touch sensor panel and configured to sense touch events at the touch sensor panel; and

circuitry coupled to the at least one sense channel and configured to;

in accordance with a determination that the at least one sense channel has sensed a touch event on the touch sensor panel during a preceding predetermined time period, operate the device in a first mode during which the circuitry performs a first touch panel scan type on the touch sensor panel with intervention from a processor configured to identify one or more touch events on the touch sensor panel, and

in accordance with a determination that the at least one sense channel has not sensed a touch event on the touch sensor panel during the preceding predetermined time period;

operate the device in a second mode during which the circuitry performs a second touch panel scan type on the touch sensor panel without intervention from the processor and the circuitry performs a spectral scan of the touch sensor panel without intervention from the processor, a spectral scan output generated from the spectral scan, and

use at least the spectral scan output to determine one or more frequencies at which to perform the first or second touch panel scan type.

2. The touch sensitive device of claim 1, wherein the circuitry determines whether or not the at least one sense channel has sensed a touch event on the touch sensor panel during the preceding predetermined time period.

3. The touch sensitive device of claim 1, wherein:

the first touch panel scan type generates a first set of touch signals from the touch sensor panel,

the second touch panel scan type generates a second set of touch signals from the touch sensor panel, and

during the first mode, the processor processes the first set of touch signals to identify one or more touch events on the touch sensor panel based on the first set of touch signals.

4. The touch sensitive device of claim 3, wherein:

during the second mode, the processor forgoes processing the second set of touch signals.

5. The touch sensitive device of claim 1, wherein:

the first touch panel scan type has a first scan length, and

the second touch panel scan type has a second scan length, less than the first scan length.

6. The touch sensitive device of claim 1, wherein:

during the first mode, the circuitry performs a plurality of touch panel scans of the first touch panel scan type at a first rate, and

during the second mode, the circuitry performs a plurality of touch panel scans of the second touch panel scan type at a second rate, less than the first rate.

7. The touch sensitive device of claim 1, wherein:

during the first mode, the processor is active, and

during the second mode, the processor is inactive.

8. The touch sensitive device of claim 1, wherein the circuitry is further configured to:

during the first mode, perform another spectral scan of the touch sensor panel to determine one or more frequencies at which to perform the first touch panel scan type, and

during the second mode, perform the spectral scan of the touch sensor panel to determine one or more frequencies at which to perform the second touch panel scan type.

9. The touch sensitive device of claim 8, wherein:

during the first and second touch panel scan types, the circuitry is configured to drive the touch sensor panel while the at least one sense channel senses the touch sensor panel, and

during the first and second spectral scans, the circuitry is configured to forgo driving the touch sensor panel while the at least one sense channel senses the touch sensor panel.

10. A method for operating a touch sensitive device, the method comprising:

in accordance with a determination that at least one sense channel has sensed a touch event on a touch sensor panel during a preceding predetermined time period, operating the device in a first mode, comprising;

performing a first touch panel scan type on the touch sensor panel with intervention from a processor configured to identify one or more touch events on the touch sensor panel, and

in accordance with a determination that the at least one sense channel has not sensed a touch event on the touch sensor panel during the preceding predetermined time period, operating the device in a second mode, comprising;

performing a second touch panel scan type on the touch sensor panel without intervention from the processor;

performing a spectral scan of the touch sensor panel without intervention from the processor, a spectral scan output generated from the spectral scan; and

using at least the spectral scan output to determine one or more frequencies at which to perform the first or second touch panel scan type.

11. The method of claim 10, wherein:

the first touch panel scan type generates a first set of touch signals from the touch sensor panel,

the second touch panel scan type generates a second set of touch signals from the touch sensor panel, and

during the first mode, the processor processes the first set of touch signals to identify one or more touch events on the touch sensor panel based on the first set of touch signals.

12. The method of claim 11, wherein:

during the second mode, the processor forgoes processing the second set of touch signals.

13. The method of claim 10, wherein:

the first touch panel scan type has a first scan length, and

the second touch panel scan type has a second scan length, less than the first scan length.

14. The method of claim 10, wherein:

performing the first scan type comprises performing a plurality of touch panel scans of the first touch panel scan type at a first rate, and

performing the second scan type comprises performing a plurality of touch panel scans of the second touch panel scan type at a second rate, less than the first rate.

15. The method of claim 10, wherein:

during the first mode, the processor is active, and

during the second mode, the processor is inactive.

16. The method of claim 10, further comprising:

during the first mode, performing another spectral scan of the touch sensor panel to determine one or more frequencies at which to perform the first touch panel scan type, and

during the second mode, performing the spectral scan of the touch sensor panel to determine one or more frequencies at which to perform the second touch panel scan type.

17. The method of claim 16, wherein:

performing the first and second touch panel scan types comprise driving the touch sensor panel while the at least one sense channel senses the touch sensor panel, and

performing the first and second spectral scans comprise forgoing driving the touch sensor panel while the at least one sense channel senses the touch sensor panel.

18. A touch sensitive device comprising:

means for, in accordance with a determination that at least one sense channel has sensed a touch event on a touch sensor panel during a preceding predetermined time period, operating the device in a first mode, comprising;

performing a first touch panel scan type on the touch sensor panel with intervention from a processor configured to identify one or more touch events on the touch sensor panel, and

means for, in accordance with a determination that the at least one sense channel has not sensed a touch event on the touch sensor panel during the preceding predetermined time period, operating the device in a second mode, comprising;

performing a second touch panel scan type on the touch sensor panel without intervention from the processor; and

performing a spectral scan of the touch sensor panel without intervention from the processor, a spectral scan output generated from the spectral scan; and

using at least the spectral scan output to determine one or more frequencies at which to perform the first or second touch panel scan type.

19. A non-transitory computer readable storage medium storing instructions, which when executed by a touch sensitive device, cause the touch sensitive device to perform a method, the method comprising:

in accordance with a determination that at least one sense channel has sensed a touch event on a touch sensor panel during a preceding predetermined time period, operating the device in a first mode, comprising;

performing a first touch panel scan type on the touch sensor panel with intervention from a processor configured to identify one or more touch events on the touch sensor panel, and

in accordance with a determination that the at least one sense channel has not sensed a touch event on the touch sensor panel during the preceding predetermined time period, operating the device in a second mode, comprising;

performing a second touch panel scan type on the touch sensor panel without intervention from the processor; and

performing a spectral scan of the touch sensor panel without intervention from the processor, a spectral scan output generated from the spectral scan; and

using at least the spectral scan output to determine one or more frequencies at which to perform the first or second touch panel scan type.

20. The non-transitory computer readable storage medium of claim 19, wherein:

the first touch panel scan type generates a first set of touch signals from the touch sensor panel,

the second touch panel scan type generates a second set of touch signals from the touch sensor panel, and

during the first mode, the processor processes the first set of touch signals to identify one or more touch events on the touch sensor panel based on the first set of touch signals.

21. The non-transitory computer readable storage medium of claim 20, wherein:

during the second mode, the processor forgoes processing the second set of touch signals.

22. The non-transitory computer readable storage medium of claim 19, wherein:

the first touch panel scan type has a first scan length, and

the second touch panel scan type has a second scan length, less than the first scan length.

23. The non-transitory computer readable storage medium of claim 19, wherein:

performing the first scan type comprises performing a plurality of touch panel scans of the first touch panel scan type at a first rate, and

performing the second scan type comprises performing a plurality of touch panel scans of the second touch panel scan type at a second rate, less than the first rate.

24. The non-transitory computer readable storage medium of claim 19, wherein:

during the first mode, the processor is active, and

during the second mode, the processor is inactive.

25. The non-transitory computer readable storage medium of claim 19, further comprising:

during the first mode, performing another spectral scan of the touch sensor panel to determine one or more frequencies at which to perform the first touch panel scan type, and

during the second mode, performing the spectral scan of the touch sensor panel to determine one or more frequencies at which to perform the second touch panel scan type.