| 摘要 |
1,261,088. Transformers. PICKER CORP. 18 June, 1969 [9 July, 1968], No. 30905/69. Heading H1T. [Also in Division H2] X-ray apparatus comprising an X-ray tube 62 fed from an A.C. supply 10, 12 by way of a transformer 14 and a rectifying device 66 is provided with a control system which includes a plurality of relays 20-32 by means of which any desired series connection of the secondary windings 14S1-14S64 may be selected so as to vary the voltage applied to the X-ray tube 62. The output voltages of the secondary windings 14S are arranged in a binary sequence 1, 2, 4, 8 ... and these may be selected in any order to provide any voltage variation in single steps from 1 to 127 and when selected the windings are connected in series with a reference secondary winding 14SR. Certain of the secondary windings are separate from the primary winding 14P whereas other secondary windings are arranged in an autotransformer mode, and the primary winding 14P is provided with tappings 14P1-14P10. The control system for energizing the relays 20-32 includes numerous transistors and thyristors which form counting devices, bistable multivibrators and various switching and adjusting devices. Adjustments are provided to limit the minimum and maximum voltages that can be applied to the tube and to control the applied voltage when the apparatus is used for radiography or fluoroscopy. The apparatus includes means for ensuring that the selection of the windings 14S to provide a required tube operating voltage is made before the tube can be energized which means includes delay means which inhibits conduction of a thyristor 58 between the transformer 14 and the rectifier 56 until the end of the delay period. Means are also provided to prevent further operation of the relay selecting system once an exposure has been initiated. |
