TIME MULTIPLEXED TOUCH DETECTION AND POWER CHARGING

• US 20150370410A1
• Filed: 06/23/2014
• Published: 12/24/2015
• Est. Priority Date: 06/23/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moyer, Todd K., Parnell, Robert S., SAUER, Christian M.
• Granted Patent: US 9,811,204 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A method of scanning a touch sensor panel while the touch sensor panel is coupled to a power adapter is disclosed. The power adapter can charge a battery of a device, but can also introduce or add noise during the process of charging the battery. To prevent adverse effects to the touch sensor panel, while the device is charging, the touch controller can time multiplex touch scan periods and inductive charging periods and can discard touch scans or touch images affected by the noise. Determining whether a touch scan is a bad touch scan can include performing a touch scan across the array of touch pixels and making a determination based on the scan profile. In some examples, the profile can be quantified using different metrics such as the shape, instantaneous slope of tail ends, a full-width half-maximum, and a monotonicity of the curve of the scan profile.

Claims

1. A method of scanning a touch sensor panel, comprising:

acquiring data from a plurality of touch sensors;

determining whether the data includes noise, the noise generated by a charger; and

discarding the data when the data includes the noise.

2. The method of claim 1, wherein the determination includes:

determining a curve of a touch profile from the acquired data;

determining a shape of the curve; and

comparing the shape of the curve to the shape of a historical touch profile.

3. The method of claim 2, wherein the curve is a Gaussian curve.

4. The method of claim 2, wherein the determination further includes determining a slope of the curve and using the slope in the comparison.

5. The method of claim 2, wherein the determination includes determining a full-width half-maximum of the curve.

6. The method of claim 1, further comprising determining a number of scans including the noise and a total number of scans during a scan period.

7. The method of claim 6, further comprising dynamically changing at least one of a scan period, a scan frequency, and a number of touch scans within the scan period.

8. The method of claim 1, further comprising generating an indication of a first touch.

9. The method of claim 1, wherein the acquiring data includes acquiring data for a plurality of touch scans, and wherein the determining whether the data includes noise includes a time based method.

10. A method of a first device communicating with a second device, the method comprising:

sending, to a second device, one or more touch values from sense circuitry; and

receiving, from the second device, at least one of a noise-free touch image, scan period, and a number of touch scans within a scan period.

11. A touch sensor panel comprising:

sensing circuit configured to acquire data from a plurality of touch sensors;

logic configured to determine whether the data includes noise and discard the data when the data includes noise, wherein the noise is generated by a charger.

12. The touch sensor panel of claim 11, wherein the logic is further configured to determine a curve of a touch profile from the acquired data, determine a shape of the curve, and compare the shape of the curve to the shape of a historical touch profile

13. The touch sensor panel of claim 12, wherein the historical touch profile includes a predetermined curve.

14. The touch sensor panel of claim 12, wherein the logic is further configured to determine a slope of the curve and using the slope for the comparison.

15. The touch sensor panel of claim 12, wherein the logic is further configured to determine a full-width half-maximum of the curve.

16. The touch sensor panel of claim 11, wherein the logic is further configured to determine a number of scans including the noise and a total number of scans during a scan period.

17. The touch sensor panel of claim 16, wherein the logic is further configured to dynamically change at least one of a scan period, a scan frequency, and a number of touch scans within the scan period.

18. The touch sensor panel of claim 11, wherein the logic is further configured to generate an indication of a first touch.

19. A charger comprising logic configured for dynamically changing a duty cycle of a charging period.

20. The charger of claim 19, wherein the duty cycle of the charging period is less than a duty cycle of a scan period of a touch sensor panel.