Biometric piezo scanner
US7236616B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 9, 2000 |
| Grant date | Jun 26, 2007 |
| Priority date | — |
| Expiry date | Oct 6, 2021 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B8/06
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A piezoelectric thin film sensor array is used to scan and capture biometric data, for example, a fingerprint image. In one embodiment, a multi-layer structure includes a PVDF layer in between two conductor grids arranged orthogonally to one another. Urethane can be added to one side where a finger is placed. A foam substrate can be used as a support. In one feature, the PVDF, and grids can be peeled off like a label for easy replacement. Multiplexers are switched to scan the sensor. A single pixel or a group of pixels can be detected and output to an image memory. The presence of a fingerprint ridge is detected by virtue of a ring-down oscillation that arises from reflection when an electric field is applied to the piezoelectric thin film sensor array at a pixel in contact with the fingerprint ridge. For example, such a ring-down value associated with a fingerprint ridge can be detected at about 150 ns. (or 5 cycles at 30 MHZ). Other reflections indicative of additional biometrics (e.g. from tissue, blood, bone, fingernail, etc.) can also be detected. A Doppler effect due to reflections from circulating blood can also be detected. Such a Doppler effect can provide further informat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.