Cathode filament for an ultra-violet discharge lamp
US5864209A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 30, 1996 |
| Grant date | Jan 26, 1999 |
| Priority date | — |
| Expiry date | Oct 30, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/067
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A unique cathode (30) for an ultraviolet discharge lamp (10) is described. The cathode includes a triple-coil wire, i.e., the wire has a primary coil (43), a secondary coil (41) wound around the primary coil and a tertiary coil (36) wound around the secondary coil. The interstices of the primary coil and secondary coil, but not the tertiary coil, are occupied by a crystalline oxide emitter material. Filling the primary and secondary coils of the triple coil cathode provides a cathode having a greater amount of emitter material than prior art. In addition, as the outer layer of the emitter material sputters away from bombardment by positive ions, the remaining emitter material is protected by the now-exposed portion of the coil wire which protrudes beyond the remaining emitter material. Thus, incoming positive ions are apt to strike the exposed wire, and not the remaining emitter material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.