| 摘要 |
PURPOSE:To realize magnified stereo photographing by forming a filament part into triode structure and permitting the forcus in X-ray exposure to be switched by controlling the potential between the filament and a grid. CONSTITUTION:A bulb-current detecting circuit 27 shown in the figure is placed at the nearest position from an X-ray tube, in order to correctly detect the bulb current. In order to control the bulb-current signal obtained in this circuit so that it may not exceed the anode permissible input of the X-ray tube when the focus of the X-ray tube is switched, filaments are selected by inputting the output of a focus switching signal generating circuit 28. As the initial exposure focus setting signal 29 defines that X-ray is to be projected from the left focus towards a subject when X-ray photograph is taken in stereo photographing, said signal is input into the focus switching signal generating circuit 28 to operate itself, in order to permit the initial focus to be set by the initial exposure focus setting signal 29. |
