Compensating force baseline artifacts in a capacitive sensor
First Claim
1. A capacitive input device, comprising:
- sensor circuitry configured to drive a plurality of sensor electrodes with capacitive sensing signals over time to acquire capacitive values of a plurality of capacitive frames; and
a processing system, coupled to the sensor circuitry, configured to;
analyze a first capacitive frame of the plurality of capacitive frames to identify a force event based on whether a first capacitive value for the first capacitive frame exceeds a baseline value;
in response to determining that the first capacitive value does not exceed the baseline value, set the baseline value equal to the first capacitive value;
analyze a second capacitive frame of the plurality of capacitive frames acquired after the force event to determine whether a second capacitive value for the second capacitive frame exceeds the first capacitive value;
in response to determining that the second capacitive value exceeds the first capacitive value, determine whether a difference between the first capacitive value and the second capacitive value is less than a threshold;
in response to determining that the difference between the first capacitive value and the second capacitive value is less than the threshold, adjust the baseline value based on a function of the difference between the first capacitive value and the second capacitive value; and
determine force information about an input object in contact with the capacitive input device based at least in part on the plurality of capacitive frames.
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Accused Products
Abstract
An example processing system for a capacitive input device includes sensor circuitry configured to drive a plurality of sensor electrodes with capacitive sensing signals over time to acquire capacitive values of a plurality of capacitive frames. The processing system includes a determination module configured to analyze a first capacitive frame of the plurality of capacitive frames to identify a force event by detecting that a rate of change of a first capacitive value in the first capacitive frame exceeds a first threshold. The determination module is configured to determine a change in capacitance between the first capacitive value and a baseline value, and analyze a second capacitive frame of the plurality of capacitive frames acquired after the force event to adjust the baseline value responsive to a difference between the baseline value and a second capacitive value in the second capacitive frame falling below a second threshold.
31 Citations
17 Claims
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1. A capacitive input device, comprising:
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sensor circuitry configured to drive a plurality of sensor electrodes with capacitive sensing signals over time to acquire capacitive values of a plurality of capacitive frames; and a processing system, coupled to the sensor circuitry, configured to; analyze a first capacitive frame of the plurality of capacitive frames to identify a force event based on whether a first capacitive value for the first capacitive frame exceeds a baseline value; in response to determining that the first capacitive value does not exceed the baseline value, set the baseline value equal to the first capacitive value; analyze a second capacitive frame of the plurality of capacitive frames acquired after the force event to determine whether a second capacitive value for the second capacitive frame exceeds the first capacitive value; in response to determining that the second capacitive value exceeds the first capacitive value, determine whether a difference between the first capacitive value and the second capacitive value is less than a threshold; in response to determining that the difference between the first capacitive value and the second capacitive value is less than the threshold, adjust the baseline value based on a function of the difference between the first capacitive value and the second capacitive value; and determine force information about an input object in contact with the capacitive input device based at least in part on the plurality of capacitive frames. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An input device, comprising:
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a plurality of sensor electrodes disposed in a sensing region; sensor circuitry configured to drive the plurality of sensor electrodes with capacitive sensing signals over time to acquire capacitive values of a plurality of capacitive frames; and a processing system, coupled to the sensor circuitry, configured to; analyze a first capacitive frame of the plurality of capacitive frames to identify a force event based on whether a first capacitive value for the first capacitive frame exceeds a baseline value; in response to determining that the first capacitive value does not exceed the baseline value, set the baseline value equal to the first capacitive value; analyze a second capacitive frame of the plurality of capacitive frames acquired after the force event to determine whether a second capacitive value for the second capacitive frame exceeds the first capacitive value; in response to determining that the second capacitive value exceeds the first capacitive value, determine whether a difference between the first capacitive value and the second capacitive value is less than a threshold; in response to determining that the difference between the first capacitive value and the second capacitive value is less than the threshold, adjust the baseline value based on a function of the difference between the first capacitive value and the second capacitive value; and determine force information about an input object in contact with the input device based at least in part on the plurality of capacitive frames. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of capacitive sensing, comprising:
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driving a plurality of sensor electrodes with capacitive sensing signals over time to acquire capacitive values of a plurality of capacitive frames; analyzing a first capacitive frame of the plurality of capacitive frames to identify a force event based on whether a first capacitive value for the first capacitive frame exceeds a baseline value; in response to determining that the first capacitive value does not exceed the baseline value, setting the baseline value equal to the first capacitive value; analyzing a second capacitive frame of the plurality of capacitive frames acquired after the force event to determine whether a second capacitive value for the second capacitive frame exceeds the first capacitive value; in response to determining that the second capacitive value exceeds the first capacitive value, determining whether a difference between the first capacitive value and the second capacitive value is less than a threshold; in response to determining that the difference between the first capacitive value and the second capacitive value is less than the threshold, adjusting the baseline value based on a function of the difference between the first capacitive value and the second capacitive value; and determining force information about an input object in contact with a capacitive input device based at least in part on the plurality of capacitive frames. - View Dependent Claims (14, 15, 16, 17)
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Specification