Pixel architecture and driving scheme for biometric sensing
First Claim
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1. A processing system for a fingerprint sensor, the processing system comprising:
- a controller circuit configured to;
charge a first sensor electrode of a plurality of sensor electrodes to a first voltage, wherein the plurality of sensor electrodes are disposed in an array;
charge a second sensor electrode to a second voltage different from the first voltage, wherein the first and second voltages are assigned to the first and second sensor electrodes according to a code, and wherein the first sensor electrode and the second sensor electrode are disposed in a same column in the array;
after charging the first and second sensor electrodes, couple the first and second sensor electrodes simultaneously to a same analog front end (AFE) to sense a combined charge on the first and second sensor electrodes; and
determine a fingerprint based at least in part on the sensed combined charge on the first and second sensor electrodes.
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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. When performing code division multiplexing (CDM), multiple sensor electrodes are coupled to the same sensor module. As such, the sensor module generates a measurement that represents the sum of the charges on the sensor electrodes rather than an individual charge on a single sensor electrode. By repeatedly sensing multiple sensor electrodes in parallel, the input device can determine a change of capacitance for each individual sensor electrode.
52 Citations
8 Claims
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1. A processing system for a fingerprint sensor, the processing system comprising:
a controller circuit configured to; charge a first sensor electrode of a plurality of sensor electrodes to a first voltage, wherein the plurality of sensor electrodes are disposed in an array; charge a second sensor electrode to a second voltage different from the first voltage, wherein the first and second voltages are assigned to the first and second sensor electrodes according to a code, and wherein the first sensor electrode and the second sensor electrode are disposed in a same column in the array; after charging the first and second sensor electrodes, couple the first and second sensor electrodes simultaneously to a same analog front end (AFE) to sense a combined charge on the first and second sensor electrodes; and determine a fingerprint based at least in part on the sensed combined charge on the first and second sensor electrodes. - View Dependent Claims (2, 3, 4, 5)
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6. An input device, comprising:
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a plurality of sensor electrodes disposed in columns forming an array, wherein each of the columns comprises a sense line coupled to an AFE and respective transistors selectively coupling sensor electrodes in the column to the sense line; and a processing system comprising an AFE coupled to the sense line, wherein the AFE is configured to; charge a first sensor electrode in at least one of the columns to a first voltage; charge a second sensor electrode in the at least one of the columns to a second voltage different from the first voltage; and after charging the first and second sensor electrodes, measure a combined charge on the first and second sensor electrodes in parallel; and wherein the processing system is configured to determine a fingerprint based at least in part on the measured combined charge on the first and second sensor electrodes. - View Dependent Claims (7, 8)
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Specification