An electronic ballast circuit

摘要

A driver waveform (30) for a gas discharge lamp is produced by a ballast circuit. The waveform (30) has a substantially vertical rising portion 831) forming an instantaneous, of time 10 musecs or so between T0 and T1, transition between currents -I1 and +I1 which are at a current value less than peak currents IP. Then in a transition rise at controlled slew rate the waveform (30) rises with a straight rising portion (32) to a steady peak current IP identified by the numeral (33). The peak current IP is maintained between T2 and T3 which accounts for between 40% and 80% of the cycle time. Then at T3 decline occurs with waveform having a declining slew rate portion (34) to time T4 when instantaneous transition between time T4 and T5 and currents +I1 to -I1 occurs. The driver waveform reduces the formation of high frequency harmonies and increases are stability.