Keywords
Citation
(2003), "Capacitive Fingerprint Sensor", Sensor Review, Vol. 23 No. 4. https://doi.org/10.1108/sr.2003.08723dad.008
Publisher
:Emerald Group Publishing Limited
Copyright © 2003, MCB UP Limited
Capacitive Fingerprint Sensor
Capacitive Fingerprint Sensor
Applicant: Veridicom Inc., USAPatent number: US6,538,456Publication date: 25 March 2003Title: Capacitive fingerprint sensor with adjustable gain
Keywords: Sensors, Fingerprints
This patent describes a method and an apparatus for detecting a fingerprint from a finger surface. The apparatus includes a planar array of capacitive sense elements disposed on a substrate. It also includes an insulating and receiving surface located above the array of sensing elements, so that when a finger is positioned above, a measurable change in capacitance occurs. The capacitance is measured by first pre-charging each sensing element, and then using a known current source to remove a fixed amount of charge from each capacitor plate. Once a fingerprint has been acquired, the quality of the fingerprint is evaluated, and if necessary, a gain parameter for the sensing elements is iteratively adjusted until a satisfactory fingerprint is acquired.