Pixelated mutual capacitance sensing for water detection
A pixelated mutual capacitance sensing configuration to detect the presence of floating water is disclosed. An integrated touch screen can be configured in a checkerboard arrangement of alternating drive pixels and sense pixels, where each drive or sense pixel can include a plurality of sub-pixels. The sense pixels can include sense sub-pixels surrounded by ground sub-pixels to reduce the baseline mutual capacitance between the drive and sense pixels. Stimulated drive pixels can capacitively couple onto the sense sub-pixels of the sense pixel, forming a baseline (no touch) mutual capacitance between the drive pixels and the sense sub-pixels. The presence of grounded objects shunts some charge to ground and reduces the mutual capacitance, while floating water provides and additional parallel mutual capacitance path that increases the mutual capacitance. Floating water can be distinguished from a grounded touch based on the direction of the change in mutual capacitance.
1 . A touch sensor panel, comprising:
an array of configurable first pixels and second pixels in an alternating checkerboard arrangement, wherein the first pixels include a first plurality of sub-pixels, the second pixels include a second plurality of sub-pixels, and the first plurality of sub-pixels and the second plurality of sub-pixels are configurable into a first pixelated mutual capacitance configuration and into a second pixelated mutual capacitance configuration; and
at least one sense circuit communicatively couplable to one or more of the first pixels and second pixels;
wherein in accordance with the first pixelated mutual capacitance configuration,
the first pixels are comprise a plurality of first drive pixels, wherein the first plurality of sub-pixels are configured as a plurality of first drive sub-pixels to receive a stimulation signal for mutual capacitance sensing,
the second pixels are comprise a plurality of first sense pixels, each first sense pixel including a first sense region and a first ground region,
each first sense region of the plurality of first sense pixels includes a first portion of the second plurality of sub-pixels configured as one or more first sense sub-pixels, each first sense sub-pixel of the one or more first sense sub-pixels positioned with respect to one or more of the first drive pixels for capacitively coupling with the one or more first drive pixels,
each first ground region of the plurality of first sense pixels includes a second portion of the second plurality of sub-pixels configured as a plurality of first ground sub-pixels,
the first ground region of each first sense pixel is positioned between the first sense region of the first sense pixel and a plurality of first drive pixels to capacitively couple with the plurality of first drive pixels, and
the at least one sense circuit is communicatively coupled to one of the first sense regions for detecting changes in mutual capacitance between one or more of the first drive pixels and the first sense region;
wherein in accordance with the second pixelated mutual capacitance configuration:
the second pixels comprise a plurality of second drive pixels, wherein the second plurality of sub-pixels are configured as a plurality of second drive sub-pixels to receive the stimulation signal,
the first pixels comprise a plurality of second sense pixels, each second sense pixel including a second sense region and a second ground region,
the second ground region of each second sense pixel includes a first portion of the first plurality of sub-pixels configured as one or more second sense sub-pixels, each second sense sub-pixels of the one or more second sense sub-pixels positioned with respect to one or more of the second drive pixels for capacitively coupling with the one or more second drive pixels,
each second ground region of the plurality of second sense pixels includes a second portion of the first plurality of sub-pixels configured as a plurality of second ground sub-pixels,
the second ground region of each second sense pixel is positioned between the second sense region of the second sense pixel and a plurality of second drive pixels to capacitively couple with the plurality of second drive pixels, and
the at least one sense circuit is communicatively coupled to one of the second sense regions for detecting changes in mutual capacitance between one or more of the second drive pixels and the second sense region; and
wherein a position of ground sub-pixels is different between the first pixelated mutual capacitance configuration and the second pixelated mutual capacitance configuration.
2 . The touch sensor panel of claim 1 , wherein in the alternating checkerboard arrangement:
each first pixel is diagonally adjacent to one or more of the first pixels; and
each second pixel is diagonally adjacent to one or more of the second pixels.
3 . The touch sensor panel of claim 1 , wherein in accordance with the first pixelated mutual capacitance configuration:
the first sense regions of the plurality of first sense pixels are separated from the plurality of first drive pixels by at least one first ground sub-pixel.
4 . The touch sensor panel of claim 1 , further comprising one or more processors communicatively coupled to the at least one sense circuit, wherein in accordance with the first pixelated mutual capacitance configuration, the one or more processors are configured to:
identify one or more of the first sense regions having increased mutual capacitance as compared to a baseline mutual capacitance as being in proximity to floating liquid, and
capture a first image of floating liquid from the identified first sense regions.
5 . The touch sensor panel of claim 4 , wherein in accordance with the first pixelated mutual capacitance configuration, the one or more processors are further configured to:
identify one or more of the first sense regions with decreased mutual capacitance as compared to the baseline mutual capacitance as being in proximity to a grounded object, and
capture a first image of grounded objects from the identified first sense regions.
6 . The touch sensor panel of claim 1 , wherein in accordance with the second pixelated mutual capacitance configuration:
the second sense regions of the plurality of second sense pixels are separated from the plurality of second drive pixels by at least one second ground sub-pixel.
7 . The touch sensor panel of claim 1 , further comprising one or more processors communicatively coupled to the at least one sense circuit, wherein in accordance with the second pixelated mutual capacitance configuration, the one or more processors are configured to:
identify one or more of the second sense regions having increased mutual capacitance as compared to a baseline mutual capacitance as being in proximity to floating liquid, and
capture a second image of floating liquid from the identified second sense regions.
8 . The touch sensor panel of claim 7 , wherein in accordance with the second pixelated mutual capacitance configuration, the one or more processors are further configured to:
identify one or more of the second sense regions with decreased mutual capacitance as compared to the baseline mutual capacitance as being in proximity to a grounded object, and
capture a second image of grounded objects from the identified second sense regions.
9 . The touch sensor panel of claim 7 , the one or more processors further configured to:
determine an image of floating liquid from the detected changes in mutual capacitance between the one or more first drive pixels and the first sense region, and from the detected changes in mutual capacitance between the one or more second drive pixels and the second sense region.
10 . The touch sensor panel of claim 1 , wherein in accordance with a bootstrapped self-capacitance configuration:
at least one of the first pixels or at least one of the second pixels is a self-capacitance sense pixel coupled to the at least one sense circuit to receive a stimulation signal for self-capacitance sensing and generate a self-capacitance sense signal;
a plurality of the first pixels laterally adjacent to the at least one self-capacitance sense pixel are guard pixels to receive a guard stimulation signal;
a plurality of the second pixels diagonally adjacent to the at least one self-capacitance sense pixel are additional guard pixels to receive the guard stimulation signal; and
the at least one sense circuit is communicatively coupled to the self-capacitance sense pixel to generate the stimulation signal for self-capacitance sensing and receive the self-capacitance sense signal for detecting changes in self-capacitance on the self-capacitance sense pixel.
11 . The touch sensor panel of claim 10 , wherein in accordance with the bootstrapped self-capacitance configuration:
the self-capacitance sense pixel is formed from a plurality of self-capacitance sense sub-pixels, each self-capacitance sense sub-pixel coupled to the at least one sense circuit for receiving the stimulation signal for self-capacitance sensing; and
the guard pixels are formed from a plurality of guard sub-pixels, each guard sub-pixel configured for receiving the guard stimulation signal.
12 . The touch sensor panel of claim 10 , further comprising one or more processors communicatively coupled to the at least one sense circuit, wherein in accordance with the bootstrapped self-capacitance configuration, the one or more processors are configured to:
identify the self-capacitance sense pixels with increased self-capacitance as compared to a baseline self-capacitance as being in proximity to a grounded object, and capture a third image of grounded objects from those self-capacitance sense pixels.
13 . The touch sensor panel of claim 1 , wherein the plurality of first ground sub-pixels surrounds the first sense sub-pixels.
14 . The touch sensor panel of claim 1 , wherein each of the first plurality of sub-pixels and each of the second plurality of sub-pixels are individually configurable.
15 . A method for detecting an object, comprising:
at a touch sensing device including a touch sensor panel and one or more processors:
arranging an array of configurable first pixels and second pixels in the touch sensor panel in an alternating checkerboard arrangement, wherein the first pixels include a first plurality of sub-pixels, the second pixels include a second plurality of sub-pixels, and the first plurality of sub-pixels and the second plurality of sub-pixels are configurable into a first pixelated mutual capacitance configuration and into a second pixelated mutual capacitance configuration;
in accordance with the first pixelated mutual capacitance configuration,
receiving a stimulation signal for mutual capacitance sensing at a plurality of first drive pixels that comprise the first pixels,
configuring the second pixels as a plurality of first sense pixels, each first sense pixel including a first sense region and a first ground region,
separating the plurality of first drive pixels from the first sense region of each first sense pixel using the first ground region of each first sense pixel, and capacitively coupling the first sense region with one or more of the first drive pixels, and
detecting changes in mutual capacitance between one or more of the first drive pixels and the first sense region of each first sense pixel using at least one sense circuit communicatively coupled to the first sense regions,
wherein the first plurality of sub-pixels are configured as a plurality of first drive sub-pixels to receive the stimulation signal,
wherein each first sense region of the plurality of first sense pixels includes a first portion of the second plurality of sub-pixels configured as one or more first sense sub-pixels,
wherein each first ground region of the plurality of first sense pixels includes a second portion of the second plurality of sub-pixels configured as a plurality of first ground sub-pixels, and
wherein the method further comprises:
receiving the stimulation signal at the plurality of first drive sub-pixels,
capacitively coupling each first sense sub-pixel with one or more of the first drive pixels; and
forming each first ground region of the plurality of first sense pixels with a plurality of first ground sub-pixels; and
in accordance with the second pixelated mutual capacitance configuration,
receiving a stimulation signal for mutual capacitance sensing at a plurality of second drive pixels that comprise the second pixels,
configuring the first pixels as a plurality of second sense pixels, each second sense pixel including a second sense region and a second ground region,
separating the plurality of second drive pixels from the second sense region of each second sense pixel using the second ground region of each second sense pixel, and capacitively coupling the second sense region with one or more of the second drive pixels, and
detecting changes in mutual capacitance between one or more of the second drive pixels and the second sense region of each second sense pixel using at least one sense circuit communicatively coupled to the second sense regions,
wherein the second plurality of sub-pixels are configured as a plurality of second drive sub-pixels to receive the stimulation signal,
wherein each second sense region of the plurality of second sense pixels includes a first portion of the first plurality of sub-pixels configured as one or more second sense sub-pixels,
wherein each second ground region of the plurality of second sense pixels includes a second portion of the first plurality of sub-pixels configured as a plurality of second ground sub-pixels, and
wherein the method further comprises:
receiving the stimulation signal at the plurality of second drive sub-pixels,
capacitively coupling each second sense sub-pixel with one or more of the second drive pixels; and
forming each second ground region of the plurality of second sense pixels with a plurality of second ground sub-pixels;
wherein a position of ground sub-pixels is different between the first pixelated mutual capacitance configuration and the second pixelated mutual capacitance configuration.
16 . The method of claim 15 , wherein in accordance with the first pixelated mutual capacitance configuration, the method further comprises:
separating the first sense regions of the plurality of first sense pixels from the plurality of first drive pixels by at least one first ground sub-pixel.
17 . The method of claim 15 , wherein in accordance with the first pixelated mutual capacitance configuration, the method further comprises:
identifying one or more of the first sense regions having increased mutual capacitance as compared to a baseline mutual capacitance as being in proximity to floating liquid, and
capturing a first image of floating liquid from the identified first sense regions.
18 . The method of claim 15 , wherein in accordance with the first pixelated mutual capacitance configuration, the method further comprises:
identifying one or more of the first sense regions with decreased mutual capacitance as compared to the baseline mutual capacitance as being in proximity to a grounded object, and
capturing a first image of grounded objects from the identified first sense regions.