GB472367A - Improvements in or relating to systems of connections for x-ray tubes having a rotary anode - Google Patents

Abstract

472,367. Control systems for X-ray tubes. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Dec. 30, 1936, No. 35760. Convention date, Jan. 2. [Class 38 (iv)] [Also in Group XXXVII] Switching control.-A supply arrangement for an X-ray tube 8 having a rotary anode 9 includes means 1-5 whereby the driving circuit 11, 12 of the anode is closed at the same time as, or later than the heating circuit 6, 7 of the cathode and is automatically interrupted after a predetermined interval during which the anode circuit may be controlled at will, this control being ineffective before and after the predetermined interval. A rocking shaft 15 is electromagnetically operated under the control of a switch 30 and carries mercury switches 1-5. The switch 1 is in the cathode heating circuit. Switch 2 is in series with a switch 3, which is a slowopening switch and controls the supply to a converter 11 connected to the 3-phase stator 12 generating the rotating field for turning the anode 9. Switch 4 is slow closing and is in series with a slow opening switch 5 controlling a switch device 13 in conjunction with a manual control 27 for supplying A.C. to the anode of the X-ray tube. All the switches are operated simultaneously on closure of the switch 30, but the heating circuit of the cathode is energized at once. The converting device 11 is energized at once but is de-energized after a predetermined delay when the switch 3 opens. Switch 4 energizes the control device 13 a predetermined time after the operation of the shaft to allow of suitable cathode heating and the anode circuits may thereafter be controlled at will by the manual switch 27 until the switch 5 opens at the same time as the switch 3 so as to de-energize the control device 13. By this means it is ensured that the anode circuit is closed only when the anode driving and cathode circuits are energized and the stator windings 12 are made light by reason of their being energized only for a predetermined interval. In a modification, Fig. 2, the shaft 15 carries only two mercury switches 3 and 4, one of which, 4 is slow closing, (see Fig. 3), and the other, 3 slow opening, (see Fig. 4). The regulating device 13 is controlled through switches 3 and 4 in series and a contact in position II of a manual three-position swatch 25. The converting device 11 is controlled through the switch 3 and the same contact in position II of the manual switch 25 in which position the circuits of the cathode heater and the electromagnet 16 are also controlled. Position I of the switch 25 is an " off " position, position II gives control as in Fig. 1, position III allows of fluorescopy and in this position the cathode heating transformer 6 is supplied through a resistance 31, the controller 13 is energized only through the switch 25 so as to allow free control from the button 27 and the converter is supplied through a resistance 34 to give slow rotation of the anode. A lamp indicator 29 and a timing. indicator 28 may be provided in the control circuits of the control device 13 to indicate when it is effective and the duration of effectiveness available. The control switches 1-4 may be gas-filled triodes or they may be mercury tube switches of the rocking type. A slow closing switch, Fig. 3, of this type comprises a tube having two compartments 17, 19 joined by a tube 18 through which mercury flows slowly from the chamber 17 to the chamber 19 carrying contacts 20, 21. On reverse operation the mercury flows rapidly from the chamber 19 to the chamber 17 through a tulle 22. In a slow opening switch of this type, Fig. 4, the contacts 23, 24 are arranged along the tube 18 so that they remain connected as long as mercury is flowing from the chamber 17 to the chamber 19.