GB796740A - Improvements in or relating to x-ray apparatus supply or control circuits - Google Patents

Abstract

796,740. Control systems for space discharge apparatus. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Oct. 31, 1955 [Nov. 3, 1954], No. 31074/55. Class 38 (4). The regulator 13 of a regulating transformer 1 controlling the X-ray tube anode to cathode voltage in an X-ray apparatus supply circuit is mechanically coupled to the regulator of a variable resistor 18 connected in the tube anode to cathode supply circuit which resistor when the transformer regulator 13 is at its two extreme positions has such values that the two respective total voltage drops resulting from the X-ray tube load are substantially equal. The resistor 18 thereby compensates for variations in the volt drops in the circuit when the transformer regulator 13 is varied, and it may be connected alternatively in the primary circuit of transformer 1, and its intermediate regulating values may be either proportional to or vary as a quadratic function of the intermediate transformation ratios of transformer 1. The tube current is maintained constant upon variation of tube voltage by a variable resistor 8 connected in the tube cathode heating circuit and having its regulator coupled to voltage regulator 13. The tube current is varied by a variable resistor 10 connected in the heating circuit, and its regulator may be coupled to that 17 of a separate winding 16 of transformer 1 which winding injects into the tube anode to cathode supply circuit an auxiliary voltage which varies with the tube current so as to differ from the total voltage drop by a constant amount. At the beginning and end of load duration the current to the H.T. transformer 12 is made and broken by an electromagnetically operated switch 19 whose current is controlled by a timedetermining element 11 which may be coupled to the regulator of tube current control resistor 10 so that the tube current decreases with increasing load duration, and conversely, to prevent overloading of the tube. In the tube heating current circuit is a voltage stabilizing device 9, and between the A.C. supply line 2 and the auto-wound transformer 1 is a variable resistor 3 which is set to bring the transformer primary circuit impedance equal to that used in calibrating the apparatus or in producing a voltage graph. By means of a tapping regulator 4 a voltmeter 5 may be adjusted to a prescribed indication irrespective of variations of the supply line voltage.