| 摘要 |
<p>The invention relates to a circuit arrangement for operating a discharge lamp (L) with a substantially constant power PL by means of a switch mode power supply with variable input current Io and provided with periodically switching switching means (10) for controlling the variable input current by means of a drive signal. The drive signal generated in a drive circuit (V) is formed from a signal S1 which is proportional on the one hand to the input current and on the other hand to the lamp voltage VL and a reference signal. The circuit arrangement comprises means (IV) for generating signal S1. The power PL by good approximation thereby satisfies the relation PL = VbIo - K2/VL in which Vb = supply source voltage VL = lamp voltage K2 = proportionality constant. <IMAGE></p> |
