Finger tracking in wet environment

• US 10,642,418 B2
• Filed: 08/25/2017
• Issued: 05/05/2020
• Est. Priority Date: 04/20/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Shah, Apexit, Benbasat, Ari Y.
• Primary Examiner(s): Earles, Bryan
• Application Number:
  US15/686,969
• Publication Number:
  US 20180307374A1
• Time in Patent Office: 984 Days
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2218/08 Feature extraction
• CPC Class Codes: G06F 2218/14 by matching peak patterns
• CPC Class Codes: G06F 2218/16 by matching signal segments
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• 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: G06V 40/28 Recognition of hand or arm movements, e.g. recognition of deaf sign language static hand signs G06V40/113

Abstract

Touch input processing for touch-sensitive devices can be improved by filtering unintended contact detected on a touch-sensitive surface. In wet environments in particular, water on the touch-sensitive surface can be erroneously detected as touch input and degrade touch performance. In some examples, input patches can be classified as touch patches or non-touch patches prior to computationally-intensive touch processing. Filtering out unintended touches classified as non-touch patches can reduce processing requirements and save power. Additionally, classifying input patches can improve touch performance in wet environments. In some examples, input patches can be classified as touch patches or non-touch patches based on characteristics of edge touch nodes. In some examples, input patches can be classified as touch patches or non-touch patches based on a state-based signal threshold.

Claims

1. An electronic device comprising:

a touch-sensitive surface; and

one or more processors coupled to the touch-sensitive surface programmed to;

acquire a first touch image;

process the first touch image to identify one or more input patches;

determine a state from a first state and a second state based on an amount of floating water in the first touch image;

for a respective input patch of the one or more input patches identified in the first touch image, classify the respective input patch as a touch patch or a non-touch patch based on the state determined based on the amount of floating water in the first touch image, wherein in the first state the classification is based on one or more first criteria, and in the second state, the classification is based on one or more second criteria, different than the one or more first criteria; and

further process the first touch image to determine touch input, wherein the further processing comprises processing respective input patches classified as touch patches and forgoing processing of respective input patches classified as non-touch patches.

2. The electronic device of claim 1, wherein determining the amount of floating water comprises:

acquiring a second touch image, the second touch image generated by a stimulation guarded scan; and

subtracting the second touch image from the first touch image.

3. The electronic device of claim 1, wherein determining the state comprises:

transitioning from the first state to the second state when the amount of floating water meets a first amount of floating water threshold.

4. The electronic device of claim 1, wherein determining the state comprises:

transitioning from the second state to the first state when the amount of floating water fails to meet a second amount of floating water threshold for a threshold number of touch images.

5. The electronic device of claim 1, wherein determining the state comprises:

maintaining the state when the amount of floating water fails to meet a first amount of floating water threshold, but meets a second amount of floating water threshold.

6. The electronic device of claim 1, the one or more processors further programmed to:

for the respective input patch of the one or more input patches;

in accordance with classifying the respective input patch as a non-touch patch, when transitioning from the first state to the second state and when a corresponding respective patch was classified pre-transition a as touch patch, cancel touch input resulting from processing of the corresponding respective patch.

7. The electronic device of claim 1, the one or more processors further programmed to:

for the respective input patch of the one or more input patches;

in accordance with classifying the respective input patch as a touch patch, when transitioning from the second state to the first state and when a corresponding respective patch was classified pre-transition as a non-touch patch, reclassify the respective input patch as a non-touch patch until liftoff of an object corresponding to the corresponding respective patch or until the respective input patch meets a third signal threshold.

8. A method comprising:

acquiring a first touch image;

processing the first touch image to identify one or more input patches;

determining a state from a first state and a second state based on an amount of floating water in the first touch image;

for a respective input patch of the one or more input patches identified in the first touch image, classifying the respective input patch as a touch patch or a non-touch patch based on the state determined based on the amount of floating water in the first touch image, wherein in the first state the classification is based on one or more first criteria, and in the second state, the classification is based on one or more second criteria, different than the one or more first criteria; and

further processing the first touch image to determine touch input, wherein the further processing comprises processing respective input patches classified as touch patches and forgoing processing of respective input patches classified as non-touch patches.

9. The method of claim 8, wherein determining the amount of floating water comprises:

acquiring a second touch image, the second touch image generated by a stimulation guarded scan; and

subtracting the second touch image from the first touch image.

10. The method of claim 8, wherein determining the state comprises:

transitioning from the first state to the second state when the amount of floating water meets a first amount of floating water threshold;

transitioning from the second state to the first state when the amount of floating water fails to meet a second amount of floating water threshold for a threshold number of touch images; and

maintaining the state when the amount of floating water fails to meet the first amount of floating water threshold, but meets the second amount of floating water threshold.

11. The method of claim 8, further comprising:

for the respective input patch of the one or more input patches;

in accordance with classifying the respective input patch as a non-touch patch, when transitioning from the first state to the second state and when a corresponding respective patch was classified pre-transition a as touch patch, canceling touch input resulting from processing of the corresponding respective patch.

12. The method of claim 8, further comprising:

for the respective input patch of the one or more input patches;

in accordance with classifying the respective input patch as a touch patch, when transitioning from the second state to the first state and when a corresponding respective patch was classified pre-transition as a non-touch patch, reclassifying the respective input patch as a non-touch patch until liftoff of an object corresponding to the corresponding respective patch or until the respective input patch meets a third signal threshold.

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

acquiring a first touch image;

processing the first touch image to identify one or more input patches;

determining a state from a first state and a second state based on the first touch image;

for a respective input patch of the one or more input patches identified in the first touch image;

classifying the respective input patch as a touch patch or a non-touch patch based on the state determined based on the amount of floating water in the first touch image, wherein;

in the first state, the respective patch is classified as a touch patch when a first signal parameter associated with the respective input patch meets a first signal threshold and the respective patch is classified as a non-touch patch when the first signal parameter associated with the respective input patch fails to meet the first signal threshold; and

in the second state, the respective patch is classified as a touch patch when the first signal parameter associated with the respective input patch meets a second signal threshold, the second signal threshold greater than the first signal threshold, or when a size parameter of the respective input patch meets a size threshold, and the respective patch is classified as a non-touch patch when the first signal parameter associated with the respective input patch fails to meet the second signal threshold and the size parameter fails to meet the size threshold; and

further processing the first touch image to determine touch input, wherein the further processing comprises processing respective input patches classified as touch patches and forgoing processing of respective input patches classified as non-touch patches.

14. The non-transitory computer readable storage medium of claim 13, wherein determining the state comprises:

determining a characteristic of the first touch image.

15. The non-transitory computer readable storage medium of claim 14, wherein the characteristic corresponds to an area of a touch-sensitive surface contacted by one or more floating objects.

16. The non-transitory computer readable storage medium of claim 14, wherein determining the characteristic comprises:

acquiring a second touch image, the second touch image generated by a stimulation guarded scan; and

subtracting the second touch image from the first touch image.

17. The non-transitory computer readable storage medium of claim 14, wherein determining the state comprises:

transitioning from the first state to the second state when the characteristic meets a first characteristic threshold.

18. The non-transitory computer readable storage medium of claim 14, wherein determining the state comprises:

transitioning from the second state to the first state when the characteristic fails to meet a second characteristic threshold for a threshold number of touch images.

19. The non-transitory computer readable storage medium of claim 13, the method further comprising:

for the respective input patch of the one or more input patches;

in accordance with classifying the respective input patch as a non-touch patch, when transitioning from the first state to the second state and when a corresponding respective patch was classified pre-transition as a touch patch, canceling touch input resulting from processing of the corresponding respective patch.

20. The non-transitory computer readable storage medium of claim 13, the method further comprising:

for the respective input patch of the one or more input patches;

in accordance with classifying the respective input patch as a touch patch, when transitioning from the second state to the first state and when a corresponding respective patch was classified pre-transition a as non-touch patch, reclassifying the respective input patch as a non-touch patch until liftoff of an object corresponding to the corresponding respective patch or until the respective input patch meets a third signal threshold.