GB1323877A - Circuit arrangements for operating electric discharge lamps - Google Patents

Abstract

1323877 Starting discharge lamps GENERAL ELECTRIC CO Ltd 16 Oct 1970 [20 Oct 1969] 53305/69 Heading H2H An A.C. starting circuit for a discharge lamp comprises a capacitive ballast in series with two lamp terminals between two supply input terminals, and a charging circuit having at least one uni-directional element, whereby the ballast may be charged to at least substantially twice the peak voltage of the supply, so that a voltage of at least substantially three times the peak voltage of the supply can be produced across the lamp terminals. As shown in Fig. 1, a capacitor 4 is provided in series with a lamp 3, and in operation, prior to lamp ignition, a capacitor 9 charges to the peak voltage V of the supply causing a peak inverse voltage of 2V across a diode 8 which voltage is applied across the capacitor 4 via a diode and resistor branch 10, 11 which, with the diodes connected as shown, holds the terminal 1 of lamp 3 at a potential of substantially - 2V with respect to the phase terminal 6 of the supply, so that a peak voltage of -3V appears across the lamp. The resistor 11 is of a value sufficiently high to prevent significant shunting after lamp ignition. In the embodiment of Fig. 2, the ballast is divided into two substantially equal parts 14, 15 and charged to voltages of substantially - 2V, V respectively prior to ignition via respective diode, resistance branches 18, 19; 20, 21. Inductive ballast elements 5, 16, 17 may preferably be included as shown in Figs. 1, 2 respectively or in various configurations, see Figs. 3-5 (not shown), or included as a winding (24), Fig. 6 (not shown), of a flux leakage transformer (23). By a suitable combination of the charging circuits of Figs. 1 and 2, a peak voltage of substantially 4V or 5V may be produced across the lamp, see Figs. 7 and 8 respectively (not shown).