Magnetic focusing structure for three in-line gun type color picture tubes
US4310780A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 1979 |
| Grant date | Jan 12, 1982 |
| Priority date | — |
| Expiry date | Sep 6, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J29/64
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electron beam focusing structure for a three in-line gun color picture tube comprises a permanent magnet or a focusing coil and a pair of magnetic yokes made of magnetic material high in magnetic permeability and having beam-passing through-holes and being disposed opposite to each other and perpendicular to the axis of the tube, for controlling the focusing magnetic fields generated for the plural electron beams by the permanent magnet or focusing coil in such a manner that the beams converge near the phosphor screen and focused respectively on the phosphor screen. The magnetic yokes are provided with cylindrical magnetic members extending in the axial direction of the tube, the cylindrical magnetic members for the center beam being different in length from the cylindrical magnetic members for the side beams, whereby the effective pole gap lengths for the respective beams between the magnetic yokes are so controlled as to provide optimum focusing fields for the respective beams. As an alternative form of the magnetic members, recesses are provided in the periphery of the throughholes with different depths.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.