Patent ID: 7130381

Claim:
In a miniature x-ray tube having a cathode with a cathode filament, an anode and an extractor cup adjacent to the cathode, a means of connecting high voltage potential to the extractor cup, comprising: the cathode filament being supported on posts from a non-conductive cathode base, the posts being conductive and extending into the interior of the extractor cup, the filament being pre-coated with a conductive metal precursor which will evaporate from the filament and deposit conductive material on adjacent surfaces when the filament is initially heated to a predetermined temperature, the extractor cup comprising a hollow shape with conductive material at least on an inner surface of the extractor cup, and the extractor cup being secured to the base during assembly of the x-ray tube, and a shield positioned on one of the filament posts to shadow an area of the base adjacent to the one post from receiving any coating from the conductive material when evaporated off the filament, whereby after the cathode and the x-ray tube are fully assembled and evacuated, the cathode filament is heated to such predetermined temperature to evaporate the conductive precursor material to deposit the conductive material on the base and on the extractor cup, thereby connecting one side of the filament to the extractor cup via the base, so that the extractor cup will be at the high voltage potential of one side of the filament during operation of the x-ray tube.