GB397716A - Improvements in or relating to installations comprising a gasfilled electric discharge lamp - Google Patents

Abstract

397,716. Discharge lamps. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, 13D, Emmasingel, Eindhoven, Holland. Nov. 11, 1932, No. 31941. Convention date, Nov. 12, 1931. [Class 39 (i).] A gas-filled lamp having a negative characteristic and supplied with current which assumes a zero value periodically, is connected in series with a gas-filled discharge tube having a grid to which is applied a potential which becomes negative at or before the period that the discharge current is zero, and does not become zero or positive until some time after the moment that the anode becomes positive with respect to its cathode ; by varying the period of time between the moment at which the current becomes zero and the moment at which the grid potential becomes zero or positive, the average current intensity through the lamp may be regulated. As shown in Fig. 1, the lamp 1 is in series with the tube 7, the anode 6 of, which is connected with one lamp electrode 2, the other 3 being connected through the secondary 12 of a transformer with the tube cathode 5. The A.C. supply 8 is also connected with a transformer primary 16 through an inductance 15 in parallel with a variable resistance 14, the secondary 18 being connected across the grid 7 and cathode through a resistance 19. Fig. 2 shows curves of supply potential 20, the potential 21 of the grid, and the current 22 through the tube and lamp ; the current 22 passes only during a fraction of each positive half wave of the supply, and the fraction, and thus the average current intensity, can be varied by varying the lag of the grid voltage 21 by means of the resistance 14 and inductance 15. Similar circuits are shown for a lamp having two anodes. With a D.C. supply the circuit may be opened periodically by a switch and the grid potential controlled by a switch.