Patent ID: 7016468

Claim:
An x-ray imaging system comprising: a tube head connected to a control unit by means of an articulated arm, said tube head including a housing; an x-ray tube mounted within the housing for generating x-rays, wherein the x-ray tube includes an anode and an electron emitting cathode filament; a high voltage circuit for supplying an AC voltage from at least two input line voltage power lines to the x-ray tube, wherein the high voltage circuit includes a high voltage transformer having a primary winding coupled to the input line voltage and a secondary winding coupled to the anode and cathode filament of the x-ray tube; and an x-ray tube preheat control circuit coupled between the x-ray tube and the input line voltage power lines for measuring x-ray tube current and controlling operation of the x-ray tube, wherein the x-ray tube preheat control circuit includes a current feedback circuit coupled to and receiving an input from the secondary winding of the high voltage transformer for sensing current in the filament, an analog to digital converter coupled to and receiving an output from the current feedback circuit for converting the output from the current feedback circuit to a digital signal, a microprocessor coupled to the analog to digital converter, and a switching circuit coupled to the input line voltage power lines and the microprocessor for adjusting the AC voltage applied to the high voltage transformer and switching the x-ray tube between a preheat condition and an x-ray radiation emission condition.