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AssigneePatent-Treuhand-Gesellschaft Fur Elektrisch Gluhla Mpen Mbh
InventorsOlaf Busse, Klaus Orth
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The invention relates to a novel operating circuit for a low-pressure gas discharge lamp 1 in the case of which a digital controller 12 is designed such that by gradually lowering the operating frequency in the ignition procedure it initiates shutdown operations of a safety shutdown device for excessive currents through a lamp inductor 10 in order thereafter to increase the operating frequency somewhat. It is possible overall in this way to achieve an ignition, for example by repeated pulsed ignition operations as far as shutdown operations, or else by a continuous ignition operation at a minimum frequency at which no shutdown operation occurs. The invention has the advantage of being insensitive to temperature fluctuations and component tolerances and, moreover, of permitting the lamp inductor 10 to have comparatively small dimensions.
An operating circuit for a discharge lamp (1) which has an AC voltage generator (6, 7) which can generate an AC supply power with different frequencies (F) for the purpose of igniting and operating the discharge lamp (1), the operating circuit being designed in order to ignite the discharge lamp (1) at a frequency at which a resonant peak of a resonant circuit (9-11) connected to the discharge lamp (1) occurs, and having a safety shutdown device (12) which shuts down the supply power at a threshold value in the region of impermissibly high supply currents of the AC voltage generator (6, 7), characterized in that the operating circuit is designed so as gradually to lower the frequency (F) of the supply power at the start of operation in order to ignite the discharge lamp (1), and to raise the frequency (F) with reference to the shutdown frequency at which shutdown was performed when the supply power should be shut down by the safety shutdown device (12), in order to begin a new attempt at ignition.
Dependencies are inferred from the claim text.