Improvements in electric circuit arrangements for operating gas or vapour filled electric discharge lamps

摘要

730,373. Supply systems for spacs discharge apparatus.: GENERAL ELECTRIC CO., Ltd., COOPER, A. D., and NELSON, E. H. Aug. 1, 1952 [May 8, 1951], No. 10797/51. Class 38 (4). [Also in Group XL (a)] An electric circuit for operating a gas or vapour filled, e.g. H.P.M.V., discharge lamp 35 from a supply of lower voltage than that required to start the discharge but sufficient to maintain the discharge once started comprises an electromagnetic vibrator 46 whose make- and-break contacts 56, 57, serially connected with an inductance coil 45 across a supply, are automatically operated by energization and deenergization of such coil; while shunted across the contacts are serially-connected at least one capacitor 44, 52 and the primary winding 42 of a high voltage step-up transformer of which the secondary winding 40 is connected across the lamp starting electrodes, and a cut-out means is provided to render the vibrator inoperative when the lamp main discharge has started; for starting, the vibrator excites an oscillatory circuit formed by the primary winding and capacitors to generate high voltage H.F. oscillations which ionize the lamp discharge space. The cut-out means may comprise a switch or be automatic in operation upon starting of the lamp and comprise a slowly charged condenser or a relay energized by the discharge current, Figs. 1 . . . 3, not shown, or the contact 49 of a relay 50 whose coil 51 is energized by the volt drop across lamp ballast resistors 37 ... 39. The lamp starting electrodes may be the main electrodes 33SP1/SP, 34SP1/SP and the supply to the starting means and to the lamp may be the same. The transformer may be auto wound as shown, or double wound, and is, air-cored. Starting of the lamp may be facilitated by. the photo-cathode effect of a tungsten filament lamp 60 whose light causes electron emission from the cathode 33SP1/SP. A rectifier 54 shunted across the vibrator is so poled that should a D.C. supply be connected to the circuit input terminals 31, 32 in incorrect polarity the vibrator is rendered inoperative and a lamp 48 provides an indication of the wrong connection. As shown, the lamp is enclosed in a housing 35SP1/SP having a shutter 36 which is released for opening by a relay 75 when its coil 74 is energized through the contact 72 of a relay 62 whose coil 61 is in turn energized through a contact 64 of the relay 50 when the voltage across the resistors 37 ... 39 attains a value corresponding to normal operating current. Energization of relay 62 also de-energizes a relay 69 to put resistor 39 effectively in circuit to reduce the discharge current to a value suitable for when the shutter is closed; and opening of the shutter closes by mechanical means not shown a switch 67 to short resistors 38, 39 and run the lamp at the full operating current. Specification 653,131 is referred to.