Discharge lamp having vitreous shield
US4281274A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 1, 1979 |
| Grant date | Jul 28, 1981 |
| Priority date | — |
| Expiry date | Aug 1, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/96
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A jacketed metal halide discharge lamp combining a miniature arc tube containing sodium iodide and a standby filament within an outer envelope, is provided with a glass sleeve around the arc tube. The glass sleeve is preferably connected to a point of potential which is positive relative to the arc tube, suitably the anode when the arc is operated on d.c. The glass sleeve prevents sodium loss from the arc by trapping ultraviolet light and by shielding the arc from photoelectrons. The sleeve serves also to reduce color shift when the arc tube is switched over from "high" to "low", and to protect the outer bulb in the event of arc tube rupture.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.