Patent GB-762173-A (GB)
Title: Improvements in or relating to electric circuit arrangements for starting and operating from a source of supply a plurality of low pressure electric discharge lamps
IPC: H05B41/19
Filed: 1952-12-09
Abstract: 762,173. Supply systems for space-discharge devices. GENERAL ELECTRIC CO., Ltd., and CATES, J. Jan. 25, 1954 [Dec. 9, 1952], No. 31214/52. Class 38 (4). [Also in Group XL (a)] A circuit arrangement for starting and operating a plurality of electric discharge lamps, e.g. of the low-pressure mercury vapour fluorescent type, or of series combinations of such lamps as shown, 95, 108, 96, 109, connected in parallel with each other with respect to supply input terminals 91, 92, comprises a separate respective stabilizing impedance 102, 117, 103, 118 serially connected with each lamp or series combination of lamps, a main switch, not shown, connected to one input terminal and possibly other individual switches whereby an operating voltage can be applied across the two electrodes of each lamp at least one of which electrodes is heatable, and one or more starting circuits including an electrode heating switch or switches 100, 113, whereby a heating current separate from the discharge current can be passed through at least one heatable cathode 93, 106, 94, 107 in each lamp prior to starting of the lamps; the arrangement further includes an auxiliary starting circuit comprising a starting inductor 121 serially connected with a starting switch 120 between the input terminals, and a plurality of starting conductors 124, 125 connected to between the inductor 121 and switch 120 and each extending close to or in contact with one or more of the lamps; for starting closure of switch 120 permits current flow through the inductor 121 and subsequent opening of the switch produces an inductive voltage pulse which is applied simultaneously between each lamp and its associated starting conductor. In the embodiment shown, the circuit is operated from a D.C. supply connected with the polarity indicated, and one only of the series group of lamps 95, 108 may be operated by the provision of switches 127, 132 which for these lamps duplicate the functions of electrode heating and starting switches 100, 113 and 120. Resistors 97, 110, 98, 111 and 119 limit the current in the cathode heating and auxiliary starting circuits and a condenser 122 suppresses the arc across switch 120. A number of other embodiments include the features of providing a series switch in the discharge circuit of each lamp and a duplicated electrode heating and/or starting switch disposed adjacent each lamp for the individual control of such lamp, combining the latter switches into a single switch or switches passing the electrode heating current through the starting conductors and the starting inductor, and heating both cathodes of each lamp prior to starting so that the supply polarity is unimportant. The starting conductor is a wire or strip close to or attached to the lamp envelope and parallel with the axis thereof, or is a metallized layer on the envelope, and has an electricallyinsulating covering. Suitable values and constructions of circuit components are described in the Specification.