A fingerprint comparator includes a projection system including a source of light and a carrier for mounting samples of prints to be compared with an optical system for projecting the images of the samples side-by-side on a screen with one image reverted and the screen divided with the images being movable toward and from the dividing line appearing to merge and emerge from the central dividing line for a precise adjacent comparison at the dividing line. An alternate embodiment uses a split vide...

A method and apparatus for rapid automatic comparison of two patterns, such as fingerprints, each of which may be randomly located and oriented within some bounded area. The patterns, or portions thereof, are optically superimposed and rapidly scanned with respect to each other in a rotated scan pattern. Reflected or transmitted incoherent radiance is sensed to provide a measure of the correlation between the two patterns. Logic circuitry including a threshold decision function signifies pattern...

A fingerprint sensor for transforming the topological pattern of a finger into an electric output signal. The sensor includes an array of cells arranged beneath a contact surface for sensing the pressure and/or temperature variations existing at the surface as a result of a fingerprint pressed against it. Each cell includes a transistor set to operate at a point within its amplification range. This operating point is varied in dependence upon the pressure and/or temperature at the adjacent conta...

The fingerprint sensor transforms the fingerprint information of a finger under investigation into an electric output signal. The sensor incorporates a contact device or sensor plate of a piezoelectric material. This sensor plate has a contact surface. The finger exercises a contact pressure thereon and changes thereby the distribution of electric charges on the contact surface. The new charge distribution is in accordance with the fingerprint pattern of the finger. The sensor further incorporat...

This invention relates to the identification of fingerprints automatically, and more particularly to a system in which conductive contact is made between a finger surface and an array of electrodes with circuit means for dividing the electrodes into groups and logic means for control of the response of the system to predetermined combinations of signals from the electrodes.

Fingerprint developers are made of woven or non-woven fabric of hydrophobic synthetic fibers which is impregnated with a 2-cyanoacrylate. The synthetic resin for the fibers may be polyethylene, polypropylene and the like. This developer is placed in a closed vessel together with an article suspected of containing a latent fingerprint with or without a cup of hot water. Rapid development of fingerprints is possible.

Method and apparatus for inkless fingerprinting employing the steps of applying a reagent comprising an aromatic polyhydroxy compound having the structural formula R-Ar(OH).sub.n wherein R is a radical selected from the group consisting of hydrogen, halogens, amides, carboxyl groups, and the n-propyl ester of a monocarboxylic acid; Ar is an aromatic selected from the group consisting of benzene and naphthalene; and n is a positive integer greater than 1, to the surface upon which the fingerprint...

An electrical method and apparatus for sensing the pattern of ridges and valleys on an individual's finger to provide binary electrical signals representative of the sensed pattern. The fingerprint sensor is constructed and defined with an integrated circuit chip having an array of sensing circuits arranged thereon in rows and columns for defining X, Y coordinates. One of the electrodes for each sensing circuit is connected to a contact pad that is electrically exposed on the surface of the inte...

A method of detection of amino acids comprising the application, to the material being tested, of a reagent comprising the following basic formula: ##STR1## where X, Y and/or Z may be nitrogen C--H, C-alkyl or C-aryl and wherein A, B, C and/or D may be an alkyl or aryl substituent either alone or in combination.

Illumination for the platen of a finger receiving imaging prism is provided from a source mounted below the prism and reflected to the platen surface at an angle greater than the critical angle, through a beam folding input prism that is positioned primarily below and behind a front edge of the platen. Transmitting and scanning optics of the system are positioned behind and below the imaging prism, and an output prism is bonded to the imaging prism to receive light reflected from the platen, to ...