PHOTOELECTRIC FINGERPRINT RIDGE COUNTER

• US 3,564,266 A
• Filed: 04/08/1968
• Issued: 02/16/1971
• Est. Priority Date: 04/08/1968
• Status: Expired due to Term

• Current Assignee: Theodore H. Klotz Jr
• Original Assignee: Theodore H. Klotz Jr
• Inventors: Klotz, Theodore H. Jr.
• Application Number:
  US04/719,528
• Time in Patent Office: 1,044 Days
• US Class Current: 377/19
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop

Abstract

Counting of ridges between the central core and the delta of a fingerprint as an identification aid is accomplished by moving a photodetector between a pair of selected points across a rearprojected image of the print. The photodetector output signal drives a counter for each crossing of the photodetector light intensity reference level in a given direction, so as to indicate the number of ridges. Photodetector-positioning apparatus is provided to reduce operator fatigue and insure accuracy.

Claims

1. Apparatus for detecting the number of ridges between the core and the delta of a fingerprint comprising:

a translucent projection screen;

means for projecting fingerprint images onto the surface of one side of said screen;

photodetector means situated on the opposite side of said translucent projection screen; and

carriage means for holding said photodetector means and for moving the photodetector means in an orthogonal coordinate system, said carriage means being rotatable so that the photodetector means can be moved along a line connecting the core and the delta of the projected fingerprint image whereby said photodetector means can respond to large changes of illumination intensity corresponding to ridges of the fingerprint by producing an electrical signal related to the changes in illumination intensity.

2. Apparatus as set forth in claim 1 wherein said line forms one axis of said orthogonal coordinate system and wherein said carriage means comprises a cantilever mounted, sectioned arm comprising at least two sections moveable relative to one another, having a free end, the endmost section of which carries said photodetector means along its length.

3. Apparatus as set forth in claim 1 wherein said line forms one axis of said orthogonal coordinate system and wherein said carriage means comprises first and second support arms orthogonally oriented to one another and moveably connected so that said first support arm can move along the length of said second support arm, said first support arm being adapted to carry said photodetector means along its length, and controllable pivotal mounting means to which one end of said second control arm is attached whereby the orthogonal coordinates defined by said first and second support arms may be rotated.

4. Apparatus as set forth in claim 1 wherein said carriage means comprises electromechanical positioning means coupled to said photodetector means for moving said photodetector means over the surface of the opposite side of said translucent screen.

5. The apparatus for detecting the number of ridges between the core and delta of a fingerprint of claim 4 including counter means coupled to said photodetector means for registering the number of ridges enCountered by said photodetector means when said photodetector means is moved in substantially a straight line between the core and delta of the projected fingerprint image.

6. The apparatus for detecting the number of ridges between the core and delta of a fingerprint of claim 1 including counter means coupled to said photodetector means for registering the number of ridges encountered by said photodetector means when said photodetector means is moved along said line.

7. The apparatus for detecting the number of ridges between the core and delta of a fingerprint of claim 5 including means coupled to said electromechanical positioning means for registering the position of said electromechanical means.

8. The apparatus for detecting the number of ridges between the core and delta of a fingerprint of claim 1 wherein said photodetector means comprises an elongated cylindrical housing tapering at one end to an aperture whereat a photodetector is positioned, said photodetector means having a photosensitive surface smaller than the width of the projected ridges of said fingerprint upon said translucent screen.

9. Apparatus for detecting the number of ridges between the core and delta of a fingerprint comprising:

a translucent optical projection screen;

means for optically projecting fingerprint images onto the surface of one side of said screen;

photodetector means situated on the opposite side of said translucent screen comprising an elongated cylindrical housing tapering at one end to an aperture whereat a photodetector is positioned and having a photosensitive surface smaller than the width of the projected ridges of said fingerprint upon said translucent screen;

means for guiding said photodetector means along a straight line within a plane parallel to the plane of said translucent screen; and

mechanical linkage means for moving said guide means in mutually orthogonal directions within the plane of said guide means and pivotal means for angularly rotating said guide means within the plane of said guide means, whereby said photodetector means, being controllably positionable over the surface of the opposite side of said screen, responds to large changes of illumination intensity corresponding to ridges of the fingerprint by electrically producing output manifestations thereof.

10. Apparatus for detecting the number of ridges between the core and delta of a fingerprint comprising:

a translucent optical projection screen;

means for optically projecting fingerprint images onto the surface of one side of said screen;

photodetector means situated on the opposite side of said translucent screen;

means for guiding said photodetector means along a straight line parallel to the surface of the opposite side of said translucent screen, whereby said photodetector means, being controllably positionable over the surface of the opposite side of said screen, responds to large changes of illumination intensity corresponding to ridges of the fingerprint by electrically producing output manifestations thereof comprising;

first drive means for traversing said guide means in a first direction, second drive means for traversing said guide means in a direction orthogonal to said first direction, third drive means for traversing said guide means in an angular direction within the plane of the traversals produced by said first and second drive means, means for detecting the position of said first, second and third drive means whereat said guide means is disposed at a location parallel to a straight line extending between the core and delta of said fingerprint;

counter means coupled to said photodetector means for registering the number of ridges encountered by said photodetector means when said photodetector means is moved in substantially a straight line between the core and delta of the projected fingerprint image;

information storage means; and

gating means for passing said recorded first, second and third drive means positionS and said ridge count to said storage.