Driver apparatus for a gas discharge lamp

A driver apparatus for driving a gas discharge lamp (L), the apparatus comprising a commutator circuit, comprising:

• input terminals for receiving an input current,
• a branch comprising lamp connection terminals for connecting the lamp (L), with an inductor (L2) arranged in series with the lamp connection terminals and a capacitor (C3) arranged in parallel with the lamp connection terminals, the inductor (L2) and the capacitor (C3) having a parallel resonance frequency fR;
• and
• a controller for controlling said commutator circuit (5) so as to alternate between a first state, in which the lamp current has a first direction, and a second state, in which the lamp current has a second direction;
• wherein the controller (6) is capable of operating:
• in a steady-state mode in which alternating between said first state and said second state takes place at a relatively low commutation frequency;
• in a hot-restrike ignition mode in which alternating between said first state and said second state takes place at a first ignition frequency fP1=fR/n1, n1 being an odd integer;
• and
• in a cold-ignition mode in which alternating between said first state and said second state takes place at a second ignition frequency fP2=fR/n2, n2 being an odd integer larger than n1.