Normalizing capacitive sensing measurements to reduce effects of low ground mass and noise
First Claim
1. An input device, comprising:
- a plurality of sensor electrodes arranged in rows and columns in a sensing region of the input device, wherein each row and column comprises at least three sensor electrodes; and
a processing system coupled to the plurality of sensor electrodes, the processing system configured to;
drive a first plurality of capacitive sensing signals in parallel onto a first group of the plurality of sensor electrodes;
generate a first plurality of capacitive measurements corresponding to the first group of the plurality of sensor electrodes in response to driving the first plurality of capacitive sensing signals;
normalize a first capacitive measurement corresponding to one of the plurality of sensor electrodes in the first group using a combination of the first plurality of capacitive measurements; and
determine a location of an input object at least partially based on at least one of;
a comparison of the normalized first capacitive measurement and a detection threshold, wherein the normalized first capacitive measurement is adjusted at least partially based on a number of non-zero capacitive measurements in the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals; and
a comparison of the normalized first capacitive measurement and the detection threshold, wherein the detection threshold is adjusted at least partially based on at least a portion of the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals.
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Accused Products
Abstract
An input device can be capacitive coupled to earth ground and noise sources which can interfere with the ability of the input device to detect an input object. To mitigate the effects from these capacitive couplings, the input device drives a modulated capacitive sensing signal onto a plurality of sensor electrodes in parallel. The sensor electrodes are coupled to respective analog front ends (AFEs) which generate an output signal for each of the sensor electrodes. The input device combines the output signals for the sensor electrodes to generate a normalization value. For example, the output signals may be digital values which are summed by the input device to generate the normalization value. The input device then divides each of the output signals by the normalization value to result in a normalized signal corresponding to each of the sensor electrodes.
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Citations
20 Claims
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1. An input device, comprising:
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a plurality of sensor electrodes arranged in rows and columns in a sensing region of the input device, wherein each row and column comprises at least three sensor electrodes; and a processing system coupled to the plurality of sensor electrodes, the processing system configured to; drive a first plurality of capacitive sensing signals in parallel onto a first group of the plurality of sensor electrodes; generate a first plurality of capacitive measurements corresponding to the first group of the plurality of sensor electrodes in response to driving the first plurality of capacitive sensing signals; normalize a first capacitive measurement corresponding to one of the plurality of sensor electrodes in the first group using a combination of the first plurality of capacitive measurements; and determine a location of an input object at least partially based on at least one of; a comparison of the normalized first capacitive measurement and a detection threshold, wherein the normalized first capacitive measurement is adjusted at least partially based on a number of non-zero capacitive measurements in the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals; and a comparison of the normalized first capacitive measurement and the detection threshold, wherein the detection threshold is adjusted at least partially based on at least a portion of the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A processing system, comprising:
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a sensor module configured to drive a first plurality of capacitive sensing signals in parallel onto a first group of a plurality of sensor electrodes, the plurality of sensor electrodes are arranged in rows and columns, each row and column comprises at least three sensor electrodes; a determination module configured to; generate a first plurality of capacitive measurements corresponding to the first group of the plurality of sensor electrodes in response to driving the first plurality of capacitive sensing signals; normalize a first capacitive measurement corresponding to one of the plurality of sensor electrodes in the first group using a combination of the first plurality of capacitive measurements; and determine a location of an input object at least partially based on at least one of; a comparison of the normalized first capacitive measurement and a detection threshold, wherein the normalized first capacitive measurement is adjusted at least partially based on a number of non-zero capacitive measurements in the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals; and a comparison of the normalized first capacitive measurement and the detection threshold, wherein the detection threshold is adjusted at least partially based on at least a portion of the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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driving a first plurality of capacitive sensing signals in parallel onto a first group of a plurality of sensor electrodes, wherein the plurality of sensor electrodes are in a sensing region of an input device and are arranged in rows and columns, each row and column having at least three sensor electrodes; generating a first plurality of capacitive measurements corresponding to the first group of the plurality of sensor electrodes in response to driving the first plurality of capacitive sensing signals; normalizing a first capacitive measurement corresponding to one of the plurality of sensor electrodes in the first group using a combination of the first plurality of capacitive measurements; and determining a location of an input object at least partially based on at least one of; a comparison of the normalized first capacitive measurement and a detection threshold, wherein the normalized first capacitive measurement is adjusted at least partially based on a number of non-zero capacitive measurements in the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals; and a comparison of the normalized first capacitive measurement and the detection threshold, wherein the detection threshold s adjusted at least partially based on at least a portion of the first plurality of capacitive measurements generated in response to driving the first plurality of capacitive sensing signals. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification