Metal halide discharge lamp
US6639341B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 27, 2000 |
| Grant date | Oct 28, 2003 |
| Priority date | — |
| Expiry date | Mar 27, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/827
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A metal halide discharge lamp which is capable of reducing a color change when subjected to a variation in the lamp power and/or the voltage supplied to the lamp. The metal halide lamp has an arc tube filled with at least sodium halide and scandium halide. The arc tube is formed at its opposite ends with electrodes which gives an arc discharge therebetween. The lamp has regulator means for keeping a coldest spot temperature of the arc tube at 550° C. or more when operating the lamp at a lamp power which is 50% or rated lamp power. It is found that when the lamp is configured to have a coldest spot temperature at 550° C. or more when operating the lamp at a lamp power which is 50% of the rated lamp power, the lamp shows much less color variation even subjected to the lamp voltage variation, thereby maintaining a desired color.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.