Laser code symbol scanner employing optical filtering system having narrow band-pass characteristics and spatially separated optical filter elements with laser light collection optics arranged along laser light return path disposed therebetween
US5627359A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 11, 1995 |
| Grant date | May 6, 1997 |
| Priority date | — |
| Expiry date | May 11, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1018
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A laser bar code symbol scanner embodying a narrow band-pass optical filtering system of novel construction. A first optical filter element is installed over the light transmission aperture of the scanner housing, and has wavelength selective properties which transmit only light having wavelengths from slightly below a predetermined wavelength in the visible band of the electromagnetic spectrum (e.g., greater than slightly below 670 nanometers). A second optical filter element is installed within the housing, along the focused laser return light path between the light focusing element and the light detecting element, and transmits only light having wavelengths from slightly above the predetermined wavelength (e.g., less than slightly above 670 nanometers). Collectively, the first and second optical filter elements cooperate to form a narrow wavelength band-pass filtering system centered about the predetermined wavelength, providing improved signal-to-noise ratio. As a result of the present invention, aesthetically unappealing electro-optical components mounted within the scanner housing are hidden from plain view, while the optical filtering elements of the system can be easily and…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.