Patent ID: 8766549

Claim:
HID lighting system ( 100 ), comprising: an HID lamp ( 1 ) including a closed discharge vessel ( 2 ) having a ceramic wall which encloses a discharge space containing an ionizable filling, the lamp further including electrodes ( 3 , 4 ) of which the tips are located within said discharge space at a mutual distance (EA) defining a discharge path between them, wherein the vessel ( 2 ) has a largest internal diameter (di), and wherein the aspect ratio (EA/di) between said mutual distance and said largest internal diameter is less than 6; and a resonant electronic driver ( 10 ) for driving the HID lamp, the driver being designed for providing alternating current to the lamp and including a control device ( 30 ) for determining the current frequency; wherein the lamp has a frequency spectrum containing at least one arc-shaping acoustic resonance frequency as well as unwanted acoustic resonance frequencies; wherein the driver ( 10 ), during normal operation, is designed to provide the lamp ( 1 ) with frequency-modulated lamp current so that the lamp current has a relatively broad power spectrum within a range between 10 kHz and 200 kHz, said power spectrum including an enabling power amplitude coinciding with said arc-shaping acoustic resonance frequency while only having non-enabling power amplitudes coinciding with said unwanted acoustic resonance frequencies.