Methods and apparatus for obtaining and maintaining position information for a rotating optical element in a bar code scanner
US6454169B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 11, 2001 |
| Grant date | Sep 24, 2002 |
| Priority date | — |
| Expiry date | Jun 11, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/10623
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Techniques for determining a position for a rotating optical element, or spinner, of a bar code scanner are described. A diffractive element is positioned so as to be struck by a laser beam produced by a laser source and reflected from the spinner when the spinner is in a reference position. The diffractive element diffracts the reflected beam to produce a diffracted line which strikes a reference position photodetector, thereby causing the reference position photodetector to produce a reference position photosignal. The reference position photosignal can be read by a controller to determine when the spinner is in the reference position, and the position of a Hall sensor can be read at the same time in order to calibrate the reading of the Hall sensor with the reference position. Thereafter, the reading of the Hall sensor can be used to provide accurate position information for the sensor and the position information can be used to control activation and deactivation of the laser source when the spinner is in appropriate positions to produce a desired scan pattern.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.