Fingerprint identification apparatus

Claim 2

Optical fingerprint identification apparatus comprising means for supporting a fingerprint to be identified, means for illuminating a discrete segment of said fingerprint and producing a Fourier transform having diffraction lobes corresponding to the ridge lines in said illuminated discrete segment of said fingerprint, means for angularly scanning through 180 degrees about the center of said Fourier transform for producing output data signals representative of the presence and angular position of said diffraction lobes and producing a reset signal indicative of completion of said 180* scan, means coupled to said angular scanning means and responsive to said output data signals for storing said output data representative of the angular position of said diffraction lobes, and means coupled between said illuminating means and said angular scanning means for directing said illuminating means onto a different discrete segment of said fingerprint in response to said reset signal.

Claim 3

Optical finGerprint identification apparatus as described in claim 1 wherein said means for angularly scanning through 180 degrees about the center of said Fourier transform includes a rotatable member, first detector means cooperable with said rotatable member for producing an output signal indicative of the presence of diffraction lobes in said Fourier transform, second detector means cooperable with said rotatable member for determining the instantaneous angular position of said rotatable member, and counter means coupled to said second detector means for producing a count corresponding to the instantaneous angular position of said angular scanning means.

Claim 4

Optical fingerprint identification apparatus as recited in claim 2 wherein said means for storing is coupled to said first detector means and said counter means and includes separate storage registers corresponding respectively to each illuminated segment of said fingerprint whereby said first detector output signal produced during each 180* scan activates a corresponding storage register and said counter means applies the count corresponding to the instantaneous angular position of said rotatable member to said corresponding storage register.

Claim 5

The optical fingerprint identification apparatus as recited in claim 3 wherein said rotatable member includes light obstructing and transmitting sections and said first detector means includes a photodetector for receiving light transmitted through said rotatable member at an angular position of said rotatable member corresponding to the position of the diffraction lobes in the Fourier transform thereby producing an electrical output signal representative of the presence of the diffraction lobes.

Claim 6

The optical fingerprint identification apperatus as recited in claim 4 further including multi-position switch means having a plurality of output terminals each coupled to a corresponding trigger input terminal on an associated storage register, said switch means having a common input terminal coupled to said photodetector whereby said electrical output signal representative of the presence of the diffraction lobes is coupled through the switch means to a storage register corresponding to said illuminated segment.

Claim 7

The optical fingerprint identification apparatus as recited in claim 5 wherein said second detector means includes means for producing said reset signal and said counter includes a reset terminal coupled to said second detector means and the common terminal of said switch means whereby said switch means sequentially couples said photodetector output signal to a different storage register at the completion of each 180 degrees rotation of said rotatable member and said counter means is simultaneously reset.

Claim 8

Optical fingerprint identification apparatus as recited in claim 1 wherein said means for angularly scanning through 180 degrees includes a plurality of detectors contiguously disposed along a semi-circular path about the center of the transform, switch means having a plurality of input and output terminals and a common terminal, said input terminals being coupled to respective photodetectors in said plurality of photodetectors, pulse generator means coupled to said common terminal for sequentially stepping said common terminal to each of said input and output terminals, counter means coupled to said pulse generator means and said common terminal of said switch means for producing a count corresponding to the angular position of the photodetector coupled to the common terminal of said switch means, and said storage means includes separate storage registers, each having an actuate terminal coupled to a corresponding output terminal of said switch means and data input terminals coupled to said count means whereby said counter means applies the count in accordance with the angular position of a photodetector which senses the presence of diffraction lobes to the storage register corresponding to said photodetector.