Lighting device having a circuit including a plurality of light emitting diodes, and methods of controlling and calibrating lighting devices
US7375476B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 8, 2005 |
| Grant date | May 20, 2008 |
| Priority date | — |
| Expiry date | Jul 26, 2025 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A lighting device (132) includes a circuit having a power supply and a plurality of light emitting diodes (120) connected in series with the power supply. The plurality of light emitting diodes (120) includes at least two groups of series-connected light emitting diodes, the groups of series-connected light emitting diodes being connected in series. A different optically isolated field effect transistor (U3-U5) is connected in parallel with each group of series-connected light emitting diodes, for selectively shunting around the group of series-connected light emitting diodes. A different capacitor (C8-C10) can also be connected in parallel with each group of series-connected light emitting diodes. A controller (U2) is connected to a gate of each of the optically isolated field effect transistors (U3-U5) for selectively turning the optically isolated field effect transistors (U3-U5) on and off. Thus, the controller U2 is electrically isolated from the power supply by the optically isolated field effect transistors (U3-U5). The light emitting diodes (120) can be driven and controlled using pulse width modulation methods.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.