Method and apparatus for plural document detection
US6212130A · kind A · utility
27Cited by
4References
18Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1999 |
| Grant date | Apr 3, 2001 |
| Priority date | — |
| Expiry date | Mar 8, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0237
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
The presence of overlapped sheets on a paper transport is detected by employing such sheets as an acoustic interference filter. A beam of ultrasonic energy of appropriate frequency, angularly oriented to the planar transport path, will be attenuated to a much greater extent than the attenuation calculated based on the attenuation of a single sheet, as a result of destructive combining of wavefronts reflected from the facing surfaces of the overlapped sheets.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.