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Screen Construction for Dark Trace CRT

IP.com Disclosure Number: IPCOM000095971D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

James, PM: AUTHOR

Abstract

Scotophor flaking resulting from thermal and mechanical stresses in the repetitious erasure of a dark trace cathode ray tube screen is induced by coating the one surface of the mica substrate with stannic oxide.

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Screen Construction for Dark Trace CRT

Scotophor flaking resulting from thermal and mechanical stresses in the repetitious erasure of a dark trace cathode ray tube screen is induced by coating the one surface of the mica substrate with stannic oxide.

In drawing A, the screen of dark trace tube 1 is typically constructed by evaporating onto the electron gun-side of a mica substrate 2 layers of potassium chloride 3, aluminum 4 and a black body 5, such as carbon black. The latter two layers are sufficiently thin that the electron beam penetrates to produce tenebrescent F-centers in the potassium chloride. These layers serve to maintain the radiation of a filament 6 as heat to accomplish erasure.

Screen complexity and thermal stresses are reduced by coating either side of mica substrate 2 with stannic oxide 7. Then, potassium chloride layer 3 is deposited on the gun-side of the mica as in B. The stannic oxide is a transparent infrared absorber and reflector during filament energization and maintains even heat for erasure. The oxide also permits the elimination of aluminum and black body layers 4 and 5 and reduces the emissivity of the mica.

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