Light source including a field emission cathode, and a field emission cathode

摘要

A field emission cathode has particular use in a light source. The light source includes an evacuated container having walls, at least a portion of which consists of an outer glass layer which on at least a major part thereof is coated on the inside with a layer of phosphor forming a luminescent layer and a conductive layer forming an anode. The layer of phosphor is excited to luminescence by electron bombardment from a field emission cathode located in the interior of the container. A modulator electrode is arranged between the cathode and the anode for creating an electrical field necessary for the emission of electrons. The field emission cathode, includes a base body, and field emitting bodies extending from the base body. The base body includes a longitudinally extending core having a central axis. The field emitting bodies are elongate and are distributed along at least a part of the length of the core, extend radially outwards from the core, and have free ends provided with field emitting surfaces.