A LIGHT SOURCE, AND A FIELD EMISSION CATHODE

摘要

The light source, comprises an evacuated container having walls, including an outer glass layer (23) which on at least part thereof is coated on the inside with a layer of phosphor (24) forming a luminescent layer and a conductive layer (25) forming an anode. The phosphor (24) is excited to luminescence by electron bombardment from a field emission cathode (40) located in the interior of the container. The field emission cathode (40) comprises a carrier having a diameter in the mm range. At least a portion of the surface of the carrier is provided with a conductive layer having surface irregularities in the form of tips, having a radial extension being less than about 10 mu m. Due to the geometry and the tips, the electric field is concentrated and amplified at the field emission surface.