Fingerprint sensing system and method
First Claim
1. A fingerprint sensing system comprising:
- a sensor array having;
a plurality of sensing structures; and
read-out circuitry connected to each of said sensing structures for providing sensing signals; 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.
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Abstract
A fingerprint sensing system comprises a sensor array with a plurality of sensing structures and read-out circuitry connectable to each of the sensing structures, and power supply circuitry arranged to provide to the read-out circuitry a substantially constant supply voltage being a difference between a high potential and a low potential. The fingerprint sensing system is configured in such a way that the low potential and the high potential are variable while substantially maintaining the supply voltage, and the read-out circuitry is connectable to each of the sensing structures in such a way that a variation in the low potential and the high potential while substantially maintaining the supply voltage results in a change of the charge carried by a sensing structure connected to the read-out circuitry. The change in charge is indicative of a capacitive coupling between the sensing structure and the finger.
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Citations
15 Claims
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1. A fingerprint sensing system comprising:
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a sensor array having; a plurality of sensing structures; and read-out circuitry connected to each of said sensing structures for providing sensing signals; 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operating a fingerprint sensor comprising:
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a sensor array comprising a plurality of sensor elements; and a power supply interface having a low driving voltage potential input and a high driving voltage potential input for providing power to said sensor array, wherein said method comprises the steps of; providing a first time-varying driving voltage potential, in relation to a reference potential of a device comprising said fingerprint sensor, to said low driving voltage potential input of the power supply interface and a second time-varying driving voltage potential, in relation to a reference potential of a device comprising said fingerprint sensor, to said high driving voltage potential input of the power supply interface, said first time-varying driving voltage potential and said second time-varying driving voltage potential oscillating in phase in such a way that a difference between said second time-varying driving voltage potential and said first time-varying driving voltage potential is a substantially constant voltage; and acquiring a sensing signal from each of said sensor elements, while providing said first time-varying driving voltage potential and said second time-varying driving voltage potential. - View Dependent Claims (15)
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Specification