Self and mutual capacitance measurement in a touch screen
First Claim
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1. A capacitance sensing device comprising:
- a first plurality of capacitance sensing electrodes disposed along a first axis;
a second plurality of capacitance sensing electrodes disposed along a second axis, the second axis substantially perpendicular to the first axis; and
a controller configured to;
measure a self capacitance of either;
at least one of the first plurality of capacitance sensing electrodes or at least one of the second plurality of capacitance sensing electrodes and update a mutual capacitance baseline based on the measured self capacitance in a first mode,measure a mutual capacitance between at least one of the first plurality of capacitance sensing electrodes and at least one of the second plurality of capacitance sensing electrodes and update a self capacitance baseline based on the measured mutual capacitance in a second mode,identify a touch on the capacitance sensing device if the measured self capacitance is above a first self capacitance threshold and if the measured mutual capacitance is above a first mutual capacitance threshold so as to prevent reporting of false touches before one or more of the baselines is updated, and calculate a position of the touch on the capacitance sensing device based on one or more of the measured self capacitance and the measured mutual capacitance.
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Abstract
A water-resistant capacitance sensing apparatus comprising a plurality of capacitive sense elements and a capacitance sensing circuit configured to measure both the mutual capacitance and self-capacitance on the plurality of capacitive sense elements.
A method for water-resistant capacitance sensing, the method comprising performing a self-capacitance scan and a mutual capacitance scan, and detecting, by a processing device, a presence of an object with the plurality of sense elements. The method further determines whether the detected presence of the object is legitimate.
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Citations
20 Claims
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1. A capacitance sensing device comprising:
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a first plurality of capacitance sensing electrodes disposed along a first axis; a second plurality of capacitance sensing electrodes disposed along a second axis, the second axis substantially perpendicular to the first axis; and a controller configured to; measure a self capacitance of either;
at least one of the first plurality of capacitance sensing electrodes or at least one of the second plurality of capacitance sensing electrodes and update a mutual capacitance baseline based on the measured self capacitance in a first mode,measure a mutual capacitance between at least one of the first plurality of capacitance sensing electrodes and at least one of the second plurality of capacitance sensing electrodes and update a self capacitance baseline based on the measured mutual capacitance in a second mode, identify a touch on the capacitance sensing device if the measured self capacitance is above a first self capacitance threshold and if the measured mutual capacitance is above a first mutual capacitance threshold so as to prevent reporting of false touches before one or more of the baselines is updated, and calculate a position of the touch on the capacitance sensing device based on one or more of the measured self capacitance and the measured mutual capacitance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method comprising:
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measuring a self capacitance of at least one of a first plurality of capacitance sensing electrodes and updating a mutual capacitance baseline based on the measured self capacitance; measuring a mutual capacitance between at least one of the first plurality of capacitance sensing electrodes and at least one of a second plurality of capacitance sensing electrodes, wherein the second plurality of capacitance sensing electrodes is disposed substantially perpendicular to the first plurality of capacitance sensing electrodes; recognizing a touch on a surface above the first and second pluralities of capacitance sensing electrodes if the measured self capacitance is above a first threshold and the measured mutual capacitance is above a second threshold so as to prevent reporting of false touches before the mutual capacitance baseline is updated; calculating a first position of the touch on the surface based on the measured capacitances. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A touch screen controller configured to:
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measure a self capacitance of at least one of a first plurality of capacitance sensing electrodes in a first mode and update a mutual capacitance baseline based on the measured self capacitance; measure a mutual capacitance between at least one of the first plurality of capacitance sensing electrodes and at least one of a second plurality of capacitance sensing electrodes in a second mode; identify a touch on the capacitance sensing device if the measured self capacitance is above a first self capacitance threshold and if the measured mutual capacitance is above a first mutual capacitance threshold so as to prevent reporting of false touches before the mutual capacitance baseline is updated; and calculate a position of the touch on the first and second pluralities of a capacitance sensing electrodes. - View Dependent Claims (17, 18, 19, 20)
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Specification