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# Peripheral Logic for the Detection of Bifurcations

IP.com Disclosure Number: IPCOM000080152D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 40K

IBM

## Related People

Ho, AP: AUTHOR [+2]

## Abstract

In fingerprint detection systems which detect the bifurcations of the fingerprint as the standard for identification, a connective logic network (template) is used to map the fingerprint pattern. The peripheral logic connected to the template must perform the following functions: 1) Detect the ridge ending of a bifurcation; 2) Detect the three legs of the bifurcation; 3) Determine that the width between the legs is within a selected maximum limit; 4) Determine a location on the template Which yields a unique X-Y coordinate for a detected bifurcation; and, 5) Assure that the above functions are performed independent of the rotation of the bifurcation.

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Peripheral Logic for the Detection of Bifurcations

In fingerprint detection systems which detect the bifurcations of the fingerprint as the standard for identification, a connective logic network (template) is used to map the fingerprint pattern. The peripheral logic connected to the template must perform the following functions:
1) Detect the ridge ending of a bifurcation;
2) Detect the three legs of the bifurcation;
3) Determine that the width between the legs is within a

selected maximum limit;
4) Determine a location on the template Which yields a unique

X-Y coordinate for a detected bifurcation; and,
5) Assure that the above functions are performed independent

of the rotation of the bifurcation.

When a 12 X 12 digitized fingerprint pattern is mapped onto the template 10, the output of the template will be "1" if a conductive path is created from the high- voltage source at the center of the template to its edge. The conductive path could be from one to as many as twelve dots. The number of 1 runs in the data will indicate the number of conductive paths, where a run consists of a number of consecutive identical bits.

In the present system the leading bit of a 1 run is detected by detector 11 in a peripheral logic quadrant, denoted PLQ4. The leading bit is stored in shift register 13. The leading bit of an "0" run is detected in detector 12 and stored in JK flip-flop 14. By counting the 1's stored in the shift register 13, the number of dots in the conductive...