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US 5,736,734 AGranted
Liquid platen fingerprint image enhancement
AssigneeFingermatrix, Inc.
InventorsDaniel H. Marcus, Hakan I. Pekcan, William Chilcott, Arthur Schlang
Life of this patent
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AssigneeFingermatrix, Inc.
InventorsDaniel H. Marcus, Hakan I. Pekcan, William Chilcott, Arthur Schlang
Estimating the term…
A fingerprint enhancement system has a platen with a liquid contacting and finger-touching surface. Two collimated interrogating light beams lie below and are opposite sides of the finger-touching surface. The horizontal extensions of the light beams assume an angle of approximately forty-five degrees with the finger longitudinal axis. Side surfaces of the platen are oriented normal to the incident colliminated light beams prior to interrogation. The light beam modulated by the fingerprint passes to a reflecting mirror, imaging means and a scanner below the platen. A polarizing filter lies between the platen and reflecting mirror. A second polarizing filter lies above the platen. A contrast enhancement circuit increases the modulation of the scanned fingerprint signal and automatically adjusts the level of the modulated signal without saturation. Circuit filtering eliminates spurious input signals. Finger position sensing by a light emitting diode and photo transistor is also provided.
An optical fingerprint imaging system comprising in combination:
A method of fingerprint imaging comprising immersing the finger in a layer of liquid on a finger-touching surface, the layer of liquid being of sufficient thickness to immerse the ridges and at least a portion of the valleys of the finger surface, interrogating the finger surface by two colliminated light beams from below and respectively on opposite sides of the finger surface, the horizontal projection of the collimated light beams assuming an angle of approximately forty-five degrees with the longitudinal axis of the finger when placed on the finger-touching surface, intercepting and optically filtering by a polarizing filter the modulated light reflected from the finger surface, and thereafter reflecting and scanning the modulated light.
A fingerprint imaging system comprising in combination:
Dependencies are inferred from the claim text.