Arrangement including a gas and/or vapor discharge lamp
AssigneeU.S. Philips Corporation
InventorsJan Evert van der Werf, Jean Johan Heuvelmans, Hendricus Franciscus Johannes Jacobus VAN Tongeren
Life of this patent
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Abstract
A device for operating a low-pressure sodium vapor discharge lamp without a ballast. The electrode voltage drop near a main electrode of the sodium lamp is influenced by a change in the pre-heating current of that electrode and/or a change in the effective area of the electrode. The changed electrode voltage drop thus obtained provides a mechanism whereby any changes in the lamp current are opposed so as to produce ballast-free lamp operation.
Claims10
Apparatus for operating an electric discharge lamp substantially free of any ballast device comprising, a pair of input terminals for applying electric power to the apparatus, a substantially impedance free electric coupling means connecting the discharge lamp across the input terminals, said discharge lamp having first and second main electrode systems defining a discharge path through the lamp, one of said electrode systems comprising a preheatable electrode operable as a cathode, an auxiliary circuit responsive to the lamp current flow between the first and second main electrode systems and including means for altering the electrode voltge drop in the vicinity of at least one of said main electrode systems, said auxiliary circuit, in the operating condition of the discharge lamp, being responsive to a change in the effective value of the current flowing between the lamp first and second main electrode systems so as to change said electrode voltage drop in a manner such as to oppose said change in current between said first and second main electrode systems, said change in the electrode voltage drop being effected at least partly by changing the magnitude of the heating current supplied to said preheatable electrode.
Apparatus as claimed in claim 8 wherein said auxiliary circuit includes switching means responsive to the lamp current between said first and second electrode systems for controlling the flow of heating current from the input terminals to the preheatable electrode via a circuit that is independent of the lamp discharge path thereby to provide ballast-free operation of the lamp.
Apparatus for operating an electric discharge lamp substantially free of any ballast device comprising, a pair of input terminals for applying electric power to the apparatus, a substantially impedance free electric coupling means connecting the discharge lamp across the input terminals, said discharge lamp having two main electrode systems one of which is operable as the lamp anode, an auxiliary circuit responsive to the lamp current between said two main electrode systems and including means for altering the electrode voltage drop in the vicinity of at least one of said main electrode systems, said auxiliary circuit, in the operating condition of the discharge lamp, being responsive to a change in the effective value of the current flowing between said two main electrode systems so as to change said electrode voltage drop in a manner such as to oppose said change in current between said two main electrode systems, said change in the electrode voltage drop being effected at least partly by changing the effective area of the lamp anode.
Dependencies are inferred from the claim text.