Color picture tube having an inline electron gun with an einzel lens
US4745331A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 20, 1987 |
| Grant date | May 17, 1988 |
| Priority date | — |
| Expiry date | Jul 20, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2229/4872
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The present invention provides an improvement in color picture tubes. Such tubes include an electron gun for generating and directing three inline electron beams, a center beam and two side beams, along initially coplanar paths toward a screen of the tube. The gun includes a plurality of spaced electrodes which form a main focus lens for focusing the electron beams. The improvement comprises the plurality of spaced electrodes which form a main focus lens including three electrodes that form an einzel lens in the path of each electron beam. A first einzel lens electrode includes three inline cylinders through which the electron beams pass. A second einzel lens electrode includes a large oval cylinder that overlaps all three cylinders of the first einzel lens electrode. A third einzel lens electrode includes three inline cylinders which are overlapped by the oval cylinder. The oval cylinder includes means for shaping the main focus lens to focus the three electron beams stigmatically near ground potential and to converge the outer beams at the center of the screen.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.