Bill validator for bank note having conductive strip
US6019208A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 19, 1997 |
| Grant date | Feb 1, 2000 |
| Priority date | — |
| Expiry date | Nov 19, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07D7/10
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A device for validating the authenticity of a document uses changes in capacitance due to the presence of an electrically conductive security thread extending across the document. The device uses a drive arrangement for moving of a document such as a bank note, past a sensing arrangement which senses changes in capacitance due to movement of a security thread therepast. A frequency generator produces a high frequency time varying oscillator signal and provides this signal to an elongate oscillator electrode extending across the path of movement. A lead elongate measuring electrode is electrically conductive and positioned in front of the oscillator electrode and extends across said path and a trailing elongate measuring electrode is positioned behind the oscillator electrode and extends across the path. The signals from the measuring and the oscillator electrode are provided to a signal processing arrangement. The signal processing arrangement processes the signals relative to detect a phase shift between the signals caused by a conductive security thread passing by the electrodes. Sensing of the phase shift reduces sensitivity to variations caused by wobble of the bank note and ch…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.