Image analysis – Applications – Personnel identification
Patent
1997-05-13
2000-04-11
Boudreau, Leo H.
Image analysis
Applications
Personnel identification
382108, G06K 928, G06K 936
Patent
active
060496207
ABSTRACT:
The present invention relates to a fingerprint sensing device comprising a planar array of closely-spaced capacitive sense elements. When a finger is placed in close proximity to the sensing device, the capacitive sense elements measure a capacitance between the finger and a single capacitor plate in each sense element. This is accomplished by precharging each capacitor plate, and then using a known current source to remove a fixed amount of charge from each capacitor plate. The measured capacitance varies as a function of the distance between the capacitor plate and the finger surface. Thus, a capacitance measurement allows the distance between the capacitor plate and the finger surface to be determined. Distance measurements across the array of sense elements are combined to produce a representation of the pattern of ridges on the finger surface which comprise a fingerprint. After a fingerprint is acquired, the quality of the fingerprint is evaluated, and if necessary, a gain parameter for the sense elements is iteratively adjusted until a satisfactory fingerprint is acquired.
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Dickinson Alexander G.
McPherson Ross
Mendis Sunetra
Ross Paul C.
Boudreau Leo H.
Veridicom, Inc.
Werner Brian P.
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