Dual beam projection tube and electron lens therefor
US6369512B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 1999 |
| Grant date | Apr 9, 2002 |
| Priority date | — |
| Expiry date | Oct 4, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J29/50
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A projection tube has a phosphor-coated faceplate at one end of a vacuum envelope and a plural-beam providing electron lens structure at the opposite end thereof. The electron lens structure includes four electrodes having axially-aligned apertures defining parallel channels for the plural electron beams to pass through to be focused and converged onto a small spot on the faceplate. The first and second electrodes of the electron lens structure shape the electron beams and the third and fourth electrodes thereof converge and focus the electron beams toward the same location on the faceplate. The potential applied to the fourth electrode is at or close to the potential at the phosphor, and is substantially higher than the potential applied to the third electrode. The lens structures of the third and fourth electrodes may each include an inner electron lens structure and an outer electron lens structure. The lens structure of the invention provides a projection tube having greater brightness and/or smaller spot size than is conventionally available.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.