Built in ion pump for field emission display

Abstract

A field emission display having an ion pump, for removal of outgassed material, is described. The display has a baseplate and an opposing face plate. A substrate acts as a base for the baseplate. There are parallel, spaced conductors acting as cathode electrodes, over the substrate. An insulating layer covers the cathode electrodes and the substrate, and parallel, spaced conductors act as gate electrodes and overlay the insulating layer. There is a plurality of openings extending through the insulating layer and the gate electrodes. At each of the openings is a field emission microtip connected to and extending up from one of the cathode electrodes. The faceplate has a glass base and is mounted opposite and parallel to the baseplate. A conducting anode electrode covers the glass base. There is a pattern of phosphorescent material over the conducting anode electrode, so that when electrons which are emitted from the field emission microtips strike the pattern of phosphorescent material, light is emitted, as well as outgassed material. Ion pump cathode electrodes formed of a gettering material cover the gate electrodes, so that during display operation the outgassed material is collected at the ion pump cathode electrodes. Alternately, the ion pump cathode may be formed on a focusing electrode, on a focusing mesh, or on other electrode structures.