Liquid platen fingerprint image enhancement
US5736734A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1996 |
| Grant date | Apr 7, 1998 |
| Priority date | — |
| Expiry date | Aug 12, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C9/37
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.