Seamless electron transfer for multiple-gun direct view CRTS

Details Seamless electron transfer for multiple-gun direct view CRTS Seamless electron transfer for multiple-gun direct view CRTS

1999-08-27

2002-08-20

Patel, Nimeshkumar D. (Department: 2879)

Electric lamp and discharge devices

Cathode ray tube

Beam deflecting means

C313S440000, C313S437000, C313S415000, C313S409000, C313S002100

Reexamination Certificate

active

06437500

ABSTRACT:

BACKGROUND OF THE INVENTION
Users of direct view conventional screen cathode ray tube (CRT) television sets have been unsatisfied because the footprint of such sets takes up a large amount of room and is not aesthetically pleasing. Such problems have been exaggerated with the introduction and popularity of large size models, e.g., those greater than 32″ (measured on the diagonal) screen size. At the same time, the cost to performance ratio of such direct view CRTs is generally much better than that of thinner, rear projection sets.
As a result, there is a need for a direct view CRT set with a dramatically reduced depth, for example, one half the depth of conventional sets.
SUMMARY OF THE INVENTION
A cathode ray display tube including a tube envelope, a display screen, a pair of electron guns for directing dual electron beams to impinge upon the display screen, deflection means for deflecting the dual electron beams to produce a visual display of partially overlapping dual raster scans on the display screen, and wherein the tube envelope contains the display screen and the pair of electron guns.
In the preferred embodiment, the tube envelope includes a pair of spaced apart tube necks, each housing a different one of the electron guns. The electron guns reside in a same horizontal plane.
The deflection means include a pair of magnetic deflection yokes, each positioned around a separate tube neck. The horizontal deflection power supply includes a circuit for supplying a random current to each of the magnetic deflection yokes. This causes the transfer point of each of the dual beams, within an area of the partial overlap of the dual raster scans, to be varied to minimize the possibility of a visible seam in the visual display.
In the preferred embodiment, the CRT according to the invention is used for the display of a large screen television set including a tube envelope having a pair of tube necks and a phosphor display screen, a pair of electron guns arranged in a same horizontal plane and each positioned in a different one of the tube necks, for directing dual electron beams to impinge upon the phosphor display screen, and magnetic deflection yokes for horizontally deflecting the dual electron beams to produce a visual display of partially overlapping dual raster scans on the display screen.
Each magnetic deflection yoke is positioned around a separate tube neck. The magnetic deflection yokes cause the transfer point of each of the dual beams, within an area of the partial overlap of the dual raster scans, to be varied to minimize the possibility of a visible seam in the visual display. This effect is caused by supplying a random current to each of the magnetic deflection yokes.
The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of certain preferred embodiments of the invention, taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 3819984 (1974-06-01), Hawken
patent: 4712038 (1987-12-01), Takenaka et al.
patent: 4714856 (1987-12-01), Takenaka et al.
patent: 4777407 (1988-10-01), Takenaka et al.
patent: 5498921 (1996-03-01), Nishimura et al.
patent: 6061038 (2000-05-01), Washburn

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