Patented Aug. 12, 1947 2,425,297
UNITED STATES PATENT OFFICE 2,425,297 LAMP CIRCUIT Carl E. Atkins, Evanston, and _Frank Furedy, Chi cago, Ill., assignors, by mesne assignments, to Sun-Kraft, Inc., Chicago, Ill., a corporation of Delaware Application October 24, 1942, Serial N o. 463,256 6 Claims. (C1. A35h-24:4) 1 2 This invention relates to a circuit for ener 52, to the terminals 4 of the gaseous discharge gizing a gaseous discharge lamp by high frequen tube or lamp 2. y ' cy currents, and more particularly for energiz The negative power supply lead 54 is connect.. ing an ultra-violet, gaseous discharge lamp of the ed to the lead 26 fromthe positive side .of the electrodeless type. heater supply source. The power supply leads` I_t is an object of this invention to provide a 40 and 54 are .connected to a source having :a high frequency, energizing circuit for a portable voltage rating of the order of ninety to one >hun ultra-violet lamp so that the same may -be se dred and ten volts. lectively connected to a source of alternating The screen grids I8 and 2.0 are tied together .by current or a battery, of relatively low Voltage. a wire 56 .connected to the positive power sup It is a further object of the invention to pro` ply lead 4I) by a Wire 58, in which is interposed vide a high frequency, oscillating circuit capable a resistor 60. The control grids Maand I6 are of energization selectively from a relative low connected to the cathodes through grid resistors voltage, alternating current power supply or bat 62 and 64, respectively, the resistors being pref tery and yet supply a suflicient amount of high erably connected to the positive sides of the lila frequency power to energize an electrodeless, ul ments of the respective tubes. The control grids tra-violet lamp for therapeutic or other analog are also coupled to the oscillator coil 34, the ous uses. grid I4 .being connected by a Wire ¿66 to a .cen-> Other and further objects and advantages of denser 68, in turn connected to an intermedìatâ. the invention will be apparent from the follow tap 'I8 of the _oscillator coil ‘atv a point between ing description when taken in connection with the central tap 36 and the _end 32 of the coil, the accompanying schematic drawing of -a circuit while the control grid I6 is connected by a Wire constructed in accordance with the invention. ‘1;2 to a condenser 14, in turn connected te an As shown in the drawing, the lamp 2 may be a intermediate tap 'L6 o_f the oscillator coil .at e». quartz, ultra-violet ray lamp, ñlled with mercury 25 point between the center tap 36 and the end 3.0,. vapor, argon, neon, helium, and krypton or other A condenser ‘I8 is connected on one de tov_, suitable rare gases, and With fa globule of mer the screen grid lead 58 .and grounded at »itsether cury, after which the lamp is sealed 01T. side to the frame of the lamp as at 8g), A con. High frequency current for the excitation of denser 82. is connected on one Side .11.0 .a wire ¿8.4 the lamp is supplied thereto by external clips or 30 which joins the ñlamentsof the tube .8 >to the terminals 4, which also form means mounting the ñlaments of the tube .6, and on its .otherSlÓ-c `is lamp in its reñector. grounded to the frame _as at 8,6. It, will :be The oscillating circuit, of which the lamp 2 evident that through the condenser `=8,2 the p ' is a part, compri-ses thermionic tubes 6 and 8 tive side of the heater source and the negative having cathodes I0 and I2, control grids I4 and 35 Side 0f the plate supply >source is grounded tothe I 6, screen grids I8 and 28, and anodes or plates frame vof the lamp. 22 and 24. Each of the cathodes I0 and I2 corn The lamp 2 forms a part ofthe tuned circuit», prises dual filaments capable of energization of which the oscillator coil 34 also forms.direct current ccm. from a low voltage source of one and one-half ponent of the plate voltage by means of the con-v voltage rating. An adjustable timer v29 is con densers 50 and 5,2. The circuit is maintained in nected in the lead 26 to deenergize the tubes and balance in respect to the high frequency oscillat the lamp after .a predetermined, adjusted period 45 ing current, and parasitic oscillations .which of treatment. The plates 22 and 24 are connect would cause flickering of the tube are suppressed, ed to the opposite ends 30 and 32 of an oscillator by the connections .of the condensers 44, 1.8, and coil 3.4 having a center tap, 36 connected by Wire 82, as shown in the drawing. These condensers, 3,8 to the positive plate supply lead 40. The cen as well as the condensers 58 and 52, Servet ter tap 36, the wire 38, and also the positive vsup 50 render the lamp unit shockproof. ` ply lead 48 are grounded to the metal frame of The supply leads 26 and 28 are connected to the lamp as at 42 through a condenser 44. blades 88 and 90 of a manual selector switch 92 The opposite ends 30 and 32 of the oscillator by which they are connected selectively to con coil 34 are connected by Wires 46 and 48, respec tacts 94 and 96 or contacts 98 and |00. Simi tively, in which are interposed condensers 50 and 55 larly, the leads 54 and 40 are connected to blades 2,425,297 4 |02 and |04 of the switch 92 by which they are induction coil on opposite sides of said center connected selectively to contacts |06 and |08 tap and providing shunt tuning capacitance for or contacts ||0 and H2. said coil to determine the frequency of said os The contacts 94 and 96 are connected to the cillating current. opposite ends of a low voltage (1_.5 volts) sec 5 3. A circuit for energizing an ultra-violet, gase ondary l I 4 of a heater transformer having its pri ous discharge lamp comprising a push-pull os mary I I6 connected to the wires ||8 and |20 of cillator having a tuned tank circuit including an a. power supply cord. The contacts 98 and |00 oscillator coil, and said lamp connected in shunt `are connected to the positive and negative sides, to said coil and providing shunt tuning capaci respectively, of a battery |28 of 1.5 volts which tance for said coil to determine the frequency of may be housed in the lamp carrying case (not operation of said oscillator. shown). The contacts |06 and |08 are connected 4. A circuit for energizing an ultra-violet, gase .by wires |22 and |24 to the wires H8 and |20 of ous discharge lamp comprising a push-pull os the supply cord While the contacts ||0 and ||2 cillator having a tuned tank circuit including an are connected to the negative and positive sides, 15 oscillator coil having a center tap connected to a respectively, of a 90 volt battery |28. source of electric energy and grounded through It will be evident that upon operation of the a capacity and said lamp, said lamp being con switch 92 to its left position, the ñlaments will be nected in shunt to said coil and providing shunt connected across the secondary ||4 while the tuning capacitance for said coil to determine the plate and return leads 40 and 54 will be directly 20 frequency of operation of said oscillator. connected through the supply cord to the 110 5. A circuit for energizing an ultraviolet, gase volt alternating current power supply. Upon ous discharge lamp comprising a push-pull oscil movement of the switch 92 to its right position, lator having a pair of thermionic tubes, a tank the filaments will be connected across the 1.5 circuit connected to the plates of said tubes and volt battery while the plate and supply leads are 25 including an oscillator coil to the ends of which connected across the 90 volt battery. the lamp is connected for tuning the coil to lde The switch 92 may have a third, or mid-posi - termine the frequency of operation of the oscilla tion, as shown, in which the power leads are dis tor, said coil having a center tap forming a posi tive power supply lead for the plates of said tubes, connected from all sources. y In a preferred construction the tubes 6 and 8 30 said tubes having ñlaments, ñlament supply leads are 3Q5GT tubes and the circuit constants have connected to said filaments, a negative plate the following values: power supply lead connected to one of said fila (1) The resistors 62 and 64I-_10,000 ohms; ment leads, and condensers connected on one side (2) The resistor BIJ-2,000 ohms; to points of equal potential and connected on the (3) The condensers 44, 50, 52, 58, 14, 18 and 35 other sides to said positive and to said negative 82-250 micromicrofarads; supply leads. (4) The oscillator or induction coil 34 consists 6. A self-excited oscillator circuit for energizing of 16 turns of No. 18 cotton-covered wire on a an ultra-violet gaseous discharge lamp, compris cylindrical form 1% inches in diameter, and ing a tank circuit determining the frequency of has a winding length of one inch. The taps 10 operation of the oscillator and a pair of therm and 16 are brought out 21A; turns on each side ionic tubes connected in push-pull to said tank of the center tap 36. circuit, said tank circuit including an induction It is obvious that various changes may be made coil in the plate circuits of said tubes, and a cir in the speciñc embodiment of the invention set cuit in shunt to said coil for tuning the tank cir forth for the purposes of illustration without de 45 cuit and including a pair of coupling condensers parting from the spirit of the invention. Ac in series with said gaseous discharge lamp. cordingly the invention is not to be limited to the speciñc embodiment shown and described but CARL E. ATKINS. only as indicated in the following claims. FRANK FU'REDY. 50 What we claim is as follows: REFERENCES CITED 1. A circuit for energizing an ultra-violet gase ous discharge la-mp comprising a thermionic tube The following references are of record in the oscillator` circuit including an induction coil, and file of this patent: a circuit including the gaseous discharge lamp 55 UNITED STATES PATENTS connected across the induction coil and forming with said coil a tuned tank circuit determining Number Name Date the frequency of operation of the oscillator, 2,300,916 Furedy ______Nov. 3, 1942 2. A circuit for energizing an ultra-violet gase 2,121,829 Seaman et al ..... __ June 28, 1938 ous discharge lamp, comprising a pair of therm 1,639,805 McCullough ______Aug. 23, 1927 ionic tubes having plate, cathode, and grid elec 60 2,327,346 Furedy ______Aug, 24, 1943 trodes, an induction coil having a center tap, a 2,132,654 Smith ______Oct. 11, 1938 source of electric current connected to said center FOREIGN PATENTS tap, connections from said coil on opposite sides of said center tap to the plates of said tubes, the Number Country Date cathodes of said tubes being connected to said 65 357,492 Great Britain ______Mar. 20, 1930 source, connections from said coil on opposite OTHER REFERENÓES sides of the center tap to the control grids of said tubes to apply thereto potentials in proper phase F. E. Terman, Radio Engineering, 2d ed., 1937, to produce oscillating plate current, and a cir McGraw-Hill, N. Y. C., page 370. (Copy in Library cuit connecting the gaseous discharge lamp to said 70 of Congress.)
