Browse Prior Art Database

Polarity Control Circuit for a Fingerprint Identification System

IP.com Disclosure Number: IPCOM000080153D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Ho, AP: AUTHOR [+3]

Abstract

One technique of fingerprint detection is the detection of bifurcations in the print. Because of the inherent high-noise signal in the fingerprint, it is desirable to detect the three legs as well as the split which defines the bifurcation.

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Polarity Control Circuit for a Fingerprint Identification System

One technique of fingerprint detection is the detection of bifurcations in the print. Because of the inherent high-noise signal in the fingerprint, it is desirable to detect the three legs as well as the split which defines the bifurcation.

In a fingerprint system using a connective logic array (template) the legs and the split between them are of opposite polarities. A system for detecting the signals of opposite polarity is shown in the figure. When the video input is at a logical 1, then polarity control gate 10 causes the input to the shift register SR1 to be inverted. On the other hand, when polarity control gate is at logical 0, the input to SR1 is the correct polarity.

Thus if the output from SR1 is a logical 1, the signal is inverted in I1 and the video polarity to the template is inverted with each succeeding video line, thereby enabling splits in legs to be found on alternate lines. During periods when mixed video information is present in the template, it can be disabled.

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