Inline electron gun with negative astigmatism beam forming and dynamic quadrupole main lens
US5350967A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 28, 1991 |
| Grant date | Sep 27, 1994 |
| Priority date | — |
| Expiry date | Oct 28, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J29/628
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In an inline electron gun for use in a color cathode ray tube (CRT), a fixed, or static, electrostatic quadrupole in the low voltage beam forming region (BFR) exerts a negative astigmatism on the electron beams in reducing beam horizontal cross-section and compensating for the horizontal under-focusing of the beams by the CRT's self-converging magnetic deflection yoke. The negative astigmatism is compensated for by a dynamic electrostatic quadrupole in the CRT's main focusing lens. The electrostatic quadrupole in the CRT's BFR includes either a plurality of spaced, horizontally oriented, aligned, elongated indentations in the G.sub.2 facing surface of the G.sub.1 control grid or a plurality of spaced, vertically oriented, elongated indentations in the G.sub.1 facing surface of the G.sub.2 screen grid, where each of the indentations has an associated through-hole circular aperture through the grid. The elongated indentations cause the cross-section of each of the electron beams to become vertically elongated particularly in the deflection region, while the dynamic electrostatic quadrupole in the main focusing lens cancels the deflection yoke's negative astigmatism without affecting …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.