High-pressure sodium lamp with improved IR reflector
US4467238A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 3, 1981 |
| Grant date | Aug 21, 1984 |
| Priority date | — |
| Expiry date | Sep 3, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/35
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The efficacy of a high-pressure sodium lamp is increased significantly by enlarging the arc tube diameter and deploying a composite infrared-reflective film on the interior of the outer lamp envelope. The infrared-reflective film acts to maintain the wall temperature of the enlarged arc tube at the same optimum temperature as the arc tube wall in a conventional high-pressure sodium lamp. In one embodiment, the IR reflective film is a multi-layer composite film of In.sub.2 O.sub.3 :Sn or SnO.sub.2 :F overcoated with a TiO.sub.2 or SiO.sub.2 dielectric film. In another embodiment, a three-layer composite film is made up of TiO.sub.2, In.sub.2 O.sub.3 :Sn, or SnO.sub.2 :F, and SiO.sub.2 films sequentially overlaid on the outer envelope. The dielectric films improve lamp efficacy and enhance the high temperature chemical stability of In.sub.2 O.sub.3 :Sn and SnO.sub.2 :F. Such IR reflective films are substantially transparent to radiation in the visible region of the spectrum, but are highly reflective in the infrared portions of the spectrum.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.