Touch sensing with water rejection

Patent metadata

Field	Value
Publication number	US-2022011920-A1
Application number	US-202117448879-A
Country	US
Kind code	A1
Filing date	Sep 25, 2021
Priority date	Sep 6, 2019
Publication date	Jan 13, 2022
Grant date	—

Abstract

Techniques for rejecting apparent (but false) touches caused by objects such as water droplets located in areas with parasitic capacitive paths to ground are disclosed. To minimize these false touches, one or more guard conductors can be located in proximity to the housing and driven with a stimulation signal to shield objects from being capacitively coupled to ground through the housing. In some examples images of touch can be obtained from a non-bootstrapped or bootstrapped scan and also an extended bootstrapped scan wherein the guard conductor is driven with a stimulation signal that has the same characteristics as the stimulation signal being applied to the sensed touch nodes. In some examples, the results of the extended bootstrapped scan can be subtracted from the non-bootstrapped or bootstrapped scan to identify and reject apparent touches resulting from capacitive coupling to ground.

First claim

1 . An electronic device comprising:
a housing; a cover substrate; a touch sensor panel comprising a plurality of touch nodes that are configured to be driven with a first stimulation signal; and one or more conductors disposed between the cover substrate and the housing and electrically insulated from the housing, wherein the one or more conductors are configured to be biased at a first potential in a first mode of touch operation and driven with a second stimulation signal in a second mode of touch operation.

2 . The electronic device of claim 1 , wherein the second stimulation signal has a same frequency, a same phase, and a same amplitude as the first stimulation signal.

3 . The electronic device of claim 1 , wherein at least a portion of the one or more conductors is disposed at an edge of the cover substrate.

4 . The electronic device of claim 1 , further comprising:
one or more gaskets between the cover substrate and the housing; wherein the one or more conductors are formed in the one or more gaskets.

5 . The electronic device of claim 1 , further comprising:
sensing circuitry configured to sense the plurality of touch nodes driven with the first stimulation signal.

6 . The electronic device of claim 1 , further comprising:
processing circuitry configured to:
perform a first scan in the first mode of touch operation by driving the plurality of touch nodes of the touch sensor panel with a first stimulation signal in one or more scan steps, the first scan including first touch signals grouped into first patches indicative of objects capacitively coupled to ground; and
perform a second scan in the second mode of touch operation by driving the plurality of touch nodes of the touch sensor panel with the first stimulation signal while shielding against capacitive coupling paths to ground through the housing, the second scan including second touch signals grouped into second patches indicative of objects capacitively coupled to ground through one or more objects contacting the cover substrate of the electronic device.

7 . The electronic device of claim 6 , wherein the processing circuitry is further configured to:
determine which of the first patches are indicative of objects capacitively coupled to ground through the electronic device using results of the first scan and results of the second scan; and exclude the first patches indicative of objects capacitively coupled to ground through the electronic device from further touch processing.

8 . The electronic device of claim 6 , wherein the processing circuitry is further configured to:
determine which of the first patches are indicative of objects capacitively coupled to ground through the one or more objects using results of the first scan and results of the second scan; and further processing the first patches indicative of objects capacitively coupled to ground through the one or more objects.

9 . The electronic device of claim 1 , the touch sensing device of claim 1 , wherein the plurality of touch nodes and the one or more conductors are formed in a same layer.

10 . The electronic device of claim 1 , the touch sensing device of claim 1 , wherein the plurality of touch nodes and the one or more conductors are formed on opposite sides of the cover substrate.

11 . The electronic device of claim 1 , wherein a first conductor of the one or more conductors wraps around from a first surface of the cover substrate to a second surface of the cover substrate.

12 . The electronic device of claim 1 , wherein the plurality of touch nodes form an active touch area for the touch sensor panel and the cover substrate, and the one or more conductors are located at least partially outside the active touch area wherein the one or more conductors are an extension of one or more driven shield layers in proximity to the active touch area, the one or more conductors extending the one or more shield layers beyond the active touch area.

13 . A method comprising:
at an electronic device comprising a housing, a cover substrate, a touch sensor panel comprising a plurality of touch nodes that are configured to be driven with a first stimulation signal, and one or more conductors disposed between the cover substrate and the housing and electrically insulated from the housing:
biasing the one or more conductors at a first potential in a first mode of touch operation; and
driving the one or more conductors with a second stimulation signal in a second mode of touch operation to shield one or more objects contacting the cover substrate from capacitively coupling to ground through the housing.

14 . The method of claim 13 , wherein the second stimulation signal has a same frequency, a same phase, and a same amplitude as the first stimulation signal.

15 . The method of claim 13 , further comprising:
performing a first scan in the first mode of touch operation by driving the plurality of touch nodes of the touch sensor panel with a first stimulation signal in one or more scan steps, the first scan including first touch signals grouped into first patches indicative of objects capacitively coupled to ground; and performing a second scan in the second mode of touch operation by driving the plurality of touch nodes of the touch sensor panel with the first stimulation signal while shielding against capacitive coupling paths to ground through the housing, the second scan including second touch signals grouped into second patches indicative of objects capacitively coupled to ground through the one or more objects.

16 . The method of claim 15 , further comprising:
determining which of the first patches are indicative of objects capacitively coupled to ground through the electronic device using results of the first scan and results of the second scan; and excluding the first patches indicative of objects capacitively coupled to ground through the electronic device from further touch processing.

17 . A non-transitory computer readable storage medium storing instructions that when executed by an electronic device comprising a housing, a cover substrate, a touch sensor panel comprising a plurality of touch nodes that are configured to be driven with a first stimulation signal, and one or more conductors disposed between the cover substrate and the housing and electrically insulated from the housing, cause the electronic device to:
bias the one or more conductors at a first potential in a first mode of touch operation; and drive the one or more conductors with a second stimulation signal in a second mode of touch operation to shield one or more objects contacting the cover substrate from capacitively coupling to ground through the housing.

18 . The non-transitory computer readable storage medium of claim 17 , wherein the second stimulation signal has a same frequency, a same phase, and a same amplitude as the first stimulation signal.

19 . The non-transitory computer readable storage medium of claim 17 , the instructions, when executed by the electronic device, further cause the electronic device to:
perform a first scan in the first mode of touch operation by driving the plurality of touch nodes of the touch sensor panel with a first stimulation signal in one or more scan steps, the first scan including first touch signals grouped into first patches indicative of objects capacitively coupled to ground; and perform a second scan in the second mode of touch operation by driving the plurality of touch nodes of the touch sensor panel with the first stimulation signal while shieldi

Assignees

• Apple Inc

Inventors

• Shorten Andrew William
• Zhang Sai
• Koeberl Andreas Johannes
• Winokur Eric S
• Yang Liqun
• Pietrangelo Ii Sabino Joseph
• Jovanovic Branislav
• Benbasat Ari Y

Classifications

• G06F3/044

  by capacitive means · CPC title

• G06F3/0446

  using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes · CPC title

• G06F3/017

  Gesture based interaction, e.g. based on a set of recognized hand gestures (interaction based on gestures traced on a digitiser G06F3/04883) · CPC title

• G06F2203/04104

  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 title

• G06F3/04186 Primary

  Touch location disambiguation · CPC title