| 摘要 |
The supply circuit for discharge lamps (L) comprises an inverter (3) for generating a supply voltage at a specified switching frequency (f c) for a load circuit (15) comprising at least one lamp (L) and a resonant circuit (23, 25) in series with the electrodes (17, 19) of the said lamp. Associated with the load circuit is a control circuit (41) for turning off the supply to the load circuit in case of defective operation of the lamp (L). The control circuit (41) comprises a band-pass filter (35) centred on the switching frequency (f c) of the inverter and whose input signal is dependent on the voltage at a point (P) of the load circuit; the output signal from the filter is sent to control means (37, 39) associated with the said inverter (3) so as to turn off the supply to the load circuit in case of defective operation.
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