Browse Prior Art Database

Dark Trace Tube Screen

IP.com Disclosure Number: IPCOM000094531D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Mason, RK: AUTHOR

Abstract

Screen flaking in dark trace cathode ray tubes is reduced by using a screen substrate having a coefficient of expansion more nearly identical to that of the scotophor.

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Dark Trace Tube Screen

Screen flaking in dark trace cathode ray tubes is reduced by using a screen substrate having a coefficient of expansion more nearly identical to that of the scotophor.

Alkali halide coating 1, notably potassium chloride, when used as the scotophor in dark trace tube 2, has a tendency to flake and drop off the usual mica substrate 3. The flaking is produced by severe fissuring and high stress created by the high temperatures during erasure with filament 4. A significant reduction in flaking is achieved by substituting a different material, such as aluminum, for the mica substrate.

The aluminum must be of a sufficient thickness, approximately .005 inch, to support the scotophor. Since the substrate is too thick for viewing by light transmission through the screen, tube 2 is constructed for direct viewing. Aluminum substrate 2 with alkali halide coating 1 on it is secured to tube wall 5. Writing is accomplished by electron gun 6 obliquely disposed relative to the screen. The recorded information is viewed in the direction of the arrow through transparent area 7 in the tube wall. The substrate need not be aluminum but may also be of other materials having a coefficient of expansion nearer that of the scotophor.

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