Pixel architecture and driving scheme for biometric sensing
First Claim
1. A processing system for performing capacitive sensing, the processing system comprising:
- a controller circuit configured to apply, during a charge stage, a charging voltage to a first sensor electrode and a second sensor electrode, wherein the first sensor electrode neighbors the second sensor electrode in an array of sensor electrodes; and
a sensor circuit configured to, during a read stage;
drive the first sensor electrode to a reference voltage; and
measure a first charge stored on the first sensor electrode resulting from applying the charging voltage, wherein the controller circuit is configured to bias the second sensor electrode to the reference voltage during the read stage.
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Abstract
Embodiments herein describe an input device that includes a rectangular array of sensor electrodes connected to sensor modules that measure capacitive sensing signals corresponding to the electrodes. During a charge stage, the input device applies a charging voltage to neighboring sensor electrodes in the array. The input device then drives the neighboring sensor electrodes to a reference voltage and measures the amount of charge accumulated on at least one of the sensor electrodes. Because of the parasitic capacitance between the neighboring electrodes, driving these electrodes (even the ones not being measured) to the same charging and reference voltages reduces the effect of the parasitic capacitance on the capacitive sensing measurement. Thus, during the read stage, the measured charge is affected primarily by the capacitance between the sensor electrodes and an input object (e.g., a finger).
61 Citations
20 Claims
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1. A processing system for performing capacitive sensing, the processing system comprising:
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a controller circuit configured to apply, during a charge stage, a charging voltage to a first sensor electrode and a second sensor electrode, wherein the first sensor electrode neighbors the second sensor electrode in an array of sensor electrodes; and a sensor circuit configured to, during a read stage; drive the first sensor electrode to a reference voltage; and measure a first charge stored on the first sensor electrode resulting from applying the charging voltage, wherein the controller circuit is configured to bias the second sensor electrode to the reference voltage during the read stage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An input device, comprising:
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a plurality of sensor electrodes arranged in an array; a processing system configured to; apply, during a charge stage, a charging voltage to a first sensor electrode and a second sensor electrode of the plurality of sensor electrodes, wherein the first sensor electrode neighbors the second sensor electrode; drive, during a read stage, the first sensor electrode to a reference voltage; and measure, during the read stage, a first charge stored on the first sensor electrode resulting from applying the charging voltage, wherein the second sensor electrode is biased to the reference voltage during the read stage. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for performing capacitive sensing, the method comprising:
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applying, during a charge stage, a charging voltage to a first sensor electrode and a second sensor electrode, wherein the second sensor electrode neighbors the first sensor electrode in an array of sensor electrodes; driving, during a read stage, the first sensor electrode to a reference voltage; and measuring, during the read stage, a first charge stored on the first sensor electrode resulting from applying the charging voltage, wherein the second sensor electrode is biased to the reference voltage during the read stage. - View Dependent Claims (19, 20)
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Specification