Patent ID: 9383876
Filing Date: 2016-07-05
CPC Classification: G06F,G06K,H04N

Claim Text:
1. A fingerprint sensing system comprising: a sensor array having: a plurality of sensing structures each facing a surface of the sensor array and being arranged to capacitively couple to a finger touching said surface of the sensor array; and read-out circuitry connected to each of said sensing structures for providing sensing signals indicative of a change of a charge carried by each of said sensing structures; and power supply circuitry arranged to provide to said read-out circuitry a substantially constant supply voltage being a difference between a high driving voltage potential and a low driving voltage potential, wherein: the fingerprint sensing system is configured in such a way that, during operation of said fingerprint sensing system, said low driving voltage potential and said high driving voltage potential oscillate in phase in relation to a reference potential of a device comprising said fingerprint sensing system, while substantially maintaining said supply voltage; and said read-out circuitry is connected to each of said sensing structures in such a way that a variation in said low driving voltage potential and said high driving voltage potential while substantially maintaining said supply voltage results in a change of the charge carried by a sensing structure connected to said read-out circuitry, said change of the charge carried by said sensing structure being indicative of a capacitive coupling between said sensing structure and said finger.