Method and apparatus for controlling thermal stress in lighting devices
US7538499B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 2, 2006 |
| Grant date | May 26, 2009 |
| Priority date | — |
| Expiry date | Feb 20, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B45/18
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The present invention provides a method and apparatus for controlling the thermal stress in lighting devices, for example light-emitting elements, that are exposed to large thermal gradients typically upon start-up, for example light-emitting elements operating in relatively cold ambient environments. The present invention provides an apparatus that can reduce this thermal stress, wherein the apparatus comprises a temperature determination mechanism for evaluating the temperature of the light-emitting elements prior to activation, and a control system to control the drive current such that it is gradually ramped up to the desired steady state peak current value, wherein the ramping of the drive current is dependent on the evaluated temperature of the light-emitting element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.