Optical scanner for reading bar codes detected within a large depth of field
US4748316A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 13, 1986 |
| Grant date | May 31, 1988 |
| Priority date | — |
| Expiry date | Jun 13, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1013
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
This disclosure describes a technique for reading bar codes scanned by focussed scan lines having different focal lengths where at least one of the scan lines has a beam that is small relative to irregularities of the surface on which the label appears. The scan lines are generated using a holographic disk so as to have a predetermined focal length and focal zone. The focal zone of each generated scan line overlaps the focal point of at least one adjacent scan line. Any bar code label which might be scanned by a beam so small that it would be degraded by surface scatter noise is also scanned by a slightly larger beam. The slightly larger beam "averages out" the surface scattering noise to produce a smoother or cleaner return signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.