| 摘要 |
The invention relates to an electronic ballast for operating at least one discharge lamp (La) having an input having a first (E1) and second input connection (E2) for coupling to a DC supply voltage (UZw); an output having a first (A1) and second output connection (A2) for coupling to the at least one discharge lamp (La); a bridge circuit having at least one first (S1) and one second electronic switch (S2), wherein a series connection of the first (S1) and the second electronic switch (S2) is coupled between the first (E1) and the second input connection (E2), forming a first bridge center point (HBM1); a lamp throttle (L1) coupled between the first bridge center point (HBM1) and the first output connection (A1); at least one trapezoidal capacitor (CT) coupled in parallel with one of the electronic switches (S1, S2); a resonance capacitor (CR) coupled in parallel with the first (A1) and second output connection (A2); a control device (12) for actuating at least the first (S1) and the second electronic switch (S2) by means of an actuating signal (AL, AH), wherein the actuating signal (AL, AH) comprises an operating frequency (f) during a preheating phase (Theat) of a first (W1) and a second coil (W2) of at least one discharge lamp (La) connected between the first (A1) and the second output connection (A2), wherein the control device (12) is designed for reducing the operating frequency (f) during an ignition phase (TZ) of the discharge lamp (La); and a heating device (TR, La, Lb1, Lb2, S3, C2) coupled to the control device (12), wherein the heating device (TR, La, Lb1, Lb2, S3, C2) is further coupled to the first bridge center point (HBM1) and is designed for heating the first (W1) and the second coil (W2) of the discharge lamp (La); wherein the control device (12) is designed for activating the heating device (TR, La, Lb1, Lb2, S3, C2) at least during a predetermined period of time of the ignition phase (TZ). The invention further relates to a corresponding method for operating at least one discharge lamp. |
