Patent ID: 6873095

Claim:
A light source, comprising an evacuated container having a cylindrical shape, a diameter in the range of about 8-80 mm, and walls, at least a portion of which comprises an outer glass layer which on at least part thereof is coated on the inside with a layer of phosphor forming a luminescent layer, and a conductive layer forming an anode, which layer of phosphor is excited to luminescence by electron bombardment from a field emission cathode located in the interior of the container, wherein the field emission cathode comprises an elongate wire-shaped carrier having a cylindrical surface and a first longitudinal axis, and at least a portion of said cylindrical surface is provided with conductive surface irregularities in the form of carbon nanotubes, each having a second longitudinal axis being essentially perpendicular to the first longitudinal axis, and free ends of said nanotubes forming tips having a radial extension less than about 10 μm.