| 摘要 |
PURPOSE:To obtain a varifocal three pole capacitor type X-ray system using standard three core high voltage cable by forming a system so as to give grid bias by auto-bias of tube current itself. CONSTITUTION:The secondary winding of a filament transformer 21 is connected to a filament of a three pole X-ray tube 1, and positive side of a high voltage capacitor 25 is connected to an anode 12. Lead switches 31-33 are connected between the line connected to the filament 11 and the line connected to a grid 13 through resistances 27-29 respectively. The lead switches 31-33 drive coils 34-36 respectively. By arranging resistances 27-29 so as to have different values and selecting either one of resistances by a switch 37, the size of focal point corresponding to resistance can be selected. Therefore, the size of focal point is freely changed in connection with the size of an object or purpose of taking picture. |
