Browse Prior Art Database

Delta Gun Shadow Mask Color Cathode Ray Tube

IP.com Disclosure Number: IPCOM000052427D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Beeteson, JS: AUTHOR

Abstract

Normally the green, red and blue phosphor dots of a delta-gun shadow mask color cathode ray tube (CRT) are of equal size. Since green phosphor is more efficient in long and short persistence than the red or blue phosphors, the 'green' gun of the CRT is normally under-run to obtain a standard white.

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Delta Gun Shadow Mask Color Cathode Ray Tube

Normally the green, red and blue phosphor dots of a delta-gun shadow mask color cathode ray tube (CRT) are of equal size. Since green phosphor is more efficient in long and short persistence than the red or blue phosphors, the 'green' gun of the CRT is normally under-run to obtain a standard white.

By reducing the size of the green phosphor dot, the electron beam size being unchanged, and increasing the current of the 'green' gun, the brightness can be maintained. The red and blue phosphor dots would be typically 115 microns in diameter, and the green phosphor dot typically 73 microns in diameter.

Reducing the size of the green phosphor dot results in the elimination of purity errors which occur when the green dots are subject to printing errors. The elimination of at least one-third of the errors results in a significant improvement in CRT manufacture. An improvement in purity margin in certain horizontal and diagonal directions is also obtained. Increased purity margin and greater tolerance to screen printing errors would produce less rejects and hence a lower product cost.

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