Arrangement for and method of controlling monitor photodiode leakage current in lasers in electro-optical readers
US8167208B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 23, 2010 |
| Grant date | May 1, 2012 |
| Priority date | — |
| Expiry date | Jan 8, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/671
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an electro-optical reader, an aiming or a scanning laser has an internal laser chip and a monitor photodiode. A controller deenergizes the chip in a deenergized state, and energizes the chip to emit a laser beam with an output power in an energized state. A positive voltage power supply forward biases and maintains the photodiode at a substantially constant positive voltage below a threshold voltage, to support a substantially constant photodiode leakage current in both states. A signal processor supports a total current comprised of a main photodiode current indicative of the output power of the laser beam in the energized state and of the leakage current which flows opposite to the main current, and removes the leakage current from the total current to output only the main current in the energized state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.