SENSOR BASELINE OFFSET ADJUSTMENT

• US 20190034032A1
• Filed: 10/04/2018
• Published: 01/31/2019
• Est. Priority Date: 01/04/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: WESTERMAN, Wayne Carl
• Granted Patent: US 11,294,503 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text
• CPC Class Codes: G06T 7/337 involving reference images or patches
• CPC Class Codes: G06V 10/421 by analysing segments intersecting the pattern

Abstract

An image jaggedness filter is disclosed that can be used to detect the presence of ungrounded objects such as water droplets or coins, and delay periodic baseline adjustments until these objects are no longer present. To do otherwise could produce inaccurate normalized baseline sensor output values. The application of a global baseline offset is also disclosed to quickly modify the sensor offset values to account for conditions such as rapid temperature changes. Background pixels not part of any touch regions can be used to detect changes to no-touch sensor output values and globally modify the sensor offset values accordingly. The use of motion dominance ratios and axis domination confidence values is also disclosed to improve the accuracy of locking onto dominant motion components as part of gesture recognition.

Claims

1. An apparatus for adjusting sensor output values captured on a touch panel, the apparatus comprising:

scan logic couplable to the touch panel and configured for performing a scan of the touch panel to capture the sensor output values for a plurality of sensors on the touch panel; and

a processor coupled to the scan logic and capable of

adjusting the sensor output values using local baseline offset values for the plurality of sensors, and

adjusting the sensor output values using a global baseline offset value.

2. The apparatus of claim 1, the processor further capable of adjusting the sensor output values using the local baseline offset values by subtracting a local baseline offset value from the sensor output value captured for each of the plurality of the sensors, the local baseline offset value indicative of an amount of misalignment of the sensor output value for a particular sensor with respect to the sensor output values from other sensors.

3. The apparatus of claim 1, the processor further capable of computing the global baseline offset value based on the sensor output values, the global baseline offset value indicative of an amount of adjustment needed to reach an original baseline value.

4. The apparatus of claim 3, the processor further capable of computing the global baseline offset value based on an average of the touch values for a plurality of background pixels.

5. The apparatus of claim 4, wherein the plurality of background pixels are located in an untouched region of the touch panel.

6. The apparatus of claim 3, the processor further capable of decaying the global baseline offset value over time.

7. The apparatus of claim 6, the processor further capable of adjusting the local baseline offset values to compensate for the decaying of the global baseline offset value over time.

8. The apparatus of claim 7, wherein an incremental adjustment of the global baseline offset value is larger than the incremental adjustment of the local baseline offset value.

9. The apparatus of claim 1, the apparatus comprising at least one of a computing device, a media player, or a mobile telephone.

10. A method for adjusting sensor output values captured on a touch panel, the method comprising:

capturing the sensor output values for a plurality of sensors on the touch panel;

adjusting the sensor output values using local baseline offset values for the plurality of sensors, and

adjusting the sensor output values using a global baseline offset value.

11. The method of claim 10, further comprising adjusting the sensor output values using the local baseline offset values by subtracting a local baseline offset value from the sensor output value captured for each of the plurality of the sensors, the local baseline offset value indicative of an amount of misalignment of the sensor output value for a particular sensor with respect to the sensor output values from other sensors.

12. The method of claim 10, further comprising computing the global baseline offset value based on the sensor output values, the global baseline offset value indicative of an amount of adjustment needed to reach an original baseline value.

13. The method claim 12, further comprising computing the global baseline offset value based on an average of the touch values for a plurality of background pixels.

14. The method of claim 13, wherein the plurality of background pixels are located in an untouched region of the touch panel.

15. The method of claim 12, further comprising decaying the global baseline offset value over time.

16. The method of claim 15, further comprising adjusting the local baseline offset values to compensate for the decaying of the global baseline offset value over time.

17. The method of claim 16, wherein an incremental adjustment of the global baseline offset value is larger than the incremental adjustment of the local baseline offset value.

18. A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by one or more processors of an electronic device, cause the electronic device to perform a method comprising:

capturing the sensor output values for a plurality of sensors on the touch panel;

adjusting the sensor output values using local baseline offset values for the plurality of sensors, and

adjusting the sensor output values using a global baseline offset value.

19. The non-transitory computer readable storage medium of claim 18, the method further comprising adjusting the sensor output values using the local baseline offset values by subtracting a local baseline offset value from the sensor output value captured for each of the plurality of the sensors, the local baseline offset value indicative of an amount of misalignment of the sensor output value for a particular sensor with respect to the sensor output values from other sensors.

20. The non-transitory computer readable storage medium of claim 18, the method further comprising computing the global baseline offset value based on the sensor output values, the global baseline offset value indicative of an amount of adjustment needed to reach an original baseline value.