Abstract: A voltage control (22) controls the voltage applied between an anode (12) and a cathode filament (14) of an x-ray tube (10). A filament control (16) controls the amount of current fed through the filament. A voltage controlled oscillator (40) and counter (42) monitor the magnitude, if any, of a tube current (24) flowing between the cathode and the anode to generate x-rays (26). A microprocessor (50) calibrates the filament current such that the filament current value stored in a filament current look-up table (122) for each selectable tube voltage and tube current combination actually produces the selected tube current. The filament current is initialized (60) to a small current value and progressively incremented (66) until a commencement of the tube current (24) is monitored (64).

Abstract: A power supply (C) for an x-ray tube filament (10) selectively functions either as a constant voltage source (12) or a constant current source (14). A control circuit (A) includes a voltage controller (56) for enabling the power supply to operate as the constant voltage source in a first time period t.sub.1 to t.sub.2 during which filament temperature (40) is increasing toward a preselected filament operating temperature (42). Once the filament temperature has substantially reached its operating temperature at a time t.sub.2, a timer (52) enables a current control (84) which causes the power supply to supply a constant current across the filament.

Abstract: An exposure control (A) selectively applies electrical power across a transformer (10) of a high voltage power supply (B). The high voltage power supply boosts the voltage such that an output voltage on the order of 150 kV is provided on output lines (20+, 20-). The output lines, typically long cables, are connected with a high voltage device such as an x-ray tube (C) to control the generation of a beam of x-rays (D). Due to high internal capacitance (22, 28) of the power supply, the cables, and the x-ray tube, the output lines continue to carry a potential (34) after the end t.sub.2 of the selected duration. At the end of the selected duration, a pulser (62, 80) applies an electrical energy pulse which causes a medium in a gap (56, 76) between electrodes (52, 54; 72, 74) to be ionized. Once the medium is ionized, the stored electrical energy arcs through the ionized medium and flows quickly to ground as indicated at (42).

Abstract: An x-ray tube (A) is powered by a control circuit (C) for selectively irradiating a sheet of x-ray film (B). An operator selects the operating anode current mA for the x-ray tube, an exposure or dose value (preferably an mAs value), and a tube voltage kV on a keyboard (20). For a fixed operating voltage and selected mAs value, the film should be exposed to the same density regardless of whether a low mA and a long time or a high mA and a short time are selected. Particularly in single phase inverter control circuit and power supplies, the high current and short time exposure tend to be underdeveloped relative to low mA and long time exposures for the same mAs value. To standardize the exposure for any current and time combination of the selected mAs value, a look up table (60) is provided. The look up table is addressed by the selected kV, mA, and mAs values to retrieve an appropriate current boost value which boosts the actual current such that the film is exposed to the selected density.