MULTI-FOCAL LASER SCANNING BAR CODE SYMBOL READING SYSTEM EMPLOYING A SCAN DATA SIGNAL PROCESSOR HAVING A VARIABLE PASS-BAND FILTER STRUCTURE WITH FREQUENCY CHARACTERISTICS CONTROLLED BY MEASURING THE BEAM SPOT SPEED OF THE LASER SCANNING BEAM PRODUCING THE ANALOG SCAN DATA SIGNAL BEING PROCESSED BY SAID SCAN DATA SIGNAL PROCESSOR
US6588663B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 2000 |
| Grant date | Jul 8, 2003 |
| Priority date | — |
| Expiry date | Feb 10, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1013
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The zone laser scanning systems by processing analog scan data signals with a scan data signal processor having a plurality of pass-band filters and amplifiers that are automatically selected for passing only the spectral components of an analog scan data signal produced when a bar code symbol is scanned at a particular focal zone in the laser scanning system. Two or more different pass band filter structures can be provided for use in the scan data signal processor, wherein each pass-band filter structure is: tuned to the spectral band associated with a particular focal zone in the laser scanning system. When a bar code, symbol is scanned by a laser beam focused within the first focal zone or scanning range of the system, the pass-band filter structure associated with this focal zone or scanning range is automatically switched into operation using a control signal produced by determining the spot speed of the laser scanning beam producing the analog scan data signal being processed. Only spectral components associated with the produced analog scan data signal and noise existing over this pass-band are allowed within the analog signal processor. By virtue of the present invention, …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.