Finger surface image enhancement having liquid layer on finger touching surface of the plate
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United States of America Patent
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-
Jan 5, 1993
Issued Date -
N/A
app pub date -
Jul 11, 1991
filing date -
Jul 31, 1990
priority date (Note) -
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status (Latency Note)
Importance
Abstract
A layer of liquid, such as alcohol, water or a mixture thereof, on the finger touching surface of a platen provides an image in an optical fingerprint imaging system which assures valley and ridge definition and continuity by virtue of the liquid filling in the cracks and holes in the ridge zone, by creating an air pocket in the valley zone that holds the valleys open and by otherwise interacting with the finger to reinforce the distinction between valley and ridge zones in the optically imaged picture. Multiple interrogating light beams, each incident at greater than the critical angle on the finger touching surface of the platen assure imaging all minutia and that the valley zones in the image will be black. The technique is useful for roll prints and touch prints.
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Cited Art Landscape
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