| 摘要 |
PURPOSE:To enable at least two X-ray electric power levels to be easily and stably selected without causing any great loss by controlling the switching devices of a resonance-type inverter to control tube voltage according to tube current. CONSTITUTION:A control mechanism 5 is driven by external operation to feed a current to an X-ray tube 1 through a filament-heating circuit 8. The mechanism 5 can produce at least two kinds of current changeover signals. The output of an inverter 6A, which has a main switch element 16a and an auxiliary switch element 16b as switching devices, is minutely varied according to the change in tube current by controlling the conduction widths and the switching frequencies of the elements 16a and 16b. Due to the above structure, X-ray electric power is switched within the range of safety operation of the switching devices without any necessity of using an expensive device. |
