Browse Prior Art Database

Dual Image Dark Trace Tube

IP.com Disclosure Number: IPCOM000079984D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 36K

Publishing Venue

IBM

Related People

Kazan, B: AUTHOR

Abstract

Conventional dark-trace or cathodochromic tubes have a limited writing speed, due to the high-charge density required to darken the screen. The writing speed may be greatly enhanced by using a storage mesh and flood beam arrangement, similar to that used in transmission type storage tubes. (See "Electronic Image Storage," B. Kazan and M. Knoll, Academic Press, 1968, N.Y., N.Y.) Writing can then be accomplished in two steps: (a) charging the storage mesh by the writing beam, and (b) converting the charge pattern to a dark-trace pattern by the flood beam.

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Dual Image Dark Trace Tube

Conventional dark-trace or cathodochromic tubes have a limited writing speed, due to the high-charge density required to darken the screen. The writing speed may be greatly enhanced by using a storage mesh and flood beam arrangement, similar to that used in transmission type storage tubes. (See "Electronic Image Storage," B. Kazan and M. Knoll, Academic Press, 1968, N.Y., N.Y.) Writing can then be accomplished in two steps: (a) charging the storage mesh by the writing beam, and (b) converting the charge pattern to a dark-trace pattern by the flood beam.

A proposed arrangment is shown. This is essentially the same structure employed for transmission type viewing storage tubes, except that the luminescent phosphor screen normally used is replaced with a cathodochromic screen. In operation, electrical input signals are used to modulate the current of the scanning writing beam, producing a charge pattern of several volts on the surface of the insulator. In accordance with the charge pattern, a pattern of flood beam current will then reach the cathodochromic screen causing local darkening. In practice, the insulator surface may be charged by the writing beam in less than 1/30 second. Assuming a flood beam current of 1 ma and a screen area of about 100 cm/2/, the maximum current density at the screen will be 10/-5/ A/cm/2/. Assuming that 10 mu C/cm/2/ is required for darkening, a dark-trace image will become visible about 1 second after the charge pattern is recorded.

It is important to note that in conventional mesh-type storage tubes, the capacitance of the insulator must be made relatively high since ions generated by the flood beam cause discharge of the insulator. In the case of the proposed tube, the retention time of the charge pattern with the flood beam on need only be a few seconds, i.e., sufficient for the flood beam to produce a dark-trace image. In other words, the capacitance of the storage insulator can be greatly reduced (i.e., its thickness increased from about 1 mu to perhaps 10 mu). This results in a writing speed at...