Bar code scanner system and scanner circuitry therefor
US4970379A · kind A · utility
83Cited by
7References
30Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Oct 12, 1988 |
| Grant date | Nov 13, 1990 |
| Priority date | — |
| Expiry date | Oct 12, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2207/1018
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In an exemplary wand type bar code scanner the scanner circuit includes a first control loop for reducing the LED driving current as the D.C. voltage level supplied to the digitizer tends to exceed a selected D.C. reference value; a second control loop becomes active when the LED is shut off by the first control loop, e.g. in the presence of sunlight. The second control loop controls the gain of the scanner amplifier so that the D.C. reference level at the input to the digitizer circuit is maintained as the scanner scans bar codes in the presence of sunlight but with the LED de-energized.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.