Scan data signal processor employing band-pass filter having frequency response characteristics controlled by the depth of focus of the laser scanning beam
US6527186B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 18, 1999 |
| Grant date | Mar 4, 2003 |
| Priority date | — |
| Expiry date | Nov 18, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02E60/10
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The effects of paper/substrate noise are significantly reduced in multi-focal 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. 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, first and second derivative signals can be generated and processed to p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.