| 摘要 |
<p>Switching device suitable for operating a lamp (4) by means of a pulse-shaped voltage V1, comprising - switching means (3) for generating the pulse-shaped voltage V1 from an input voltage, V1 having an amplitude proportional to the input voltage, - a pulse width modulator (2) for supplying control pulses to the switching means, - a first auxiliary circuit (S1) for generating a first signal from the pulse-shaped voltage V1, this first signal being proportional to an average value of the pulse-shaped voltage V1, and - a control device (1) for making the first signal substantially equal to a second signal through the supply of a control signal to the pulse width modulator. According to the invention, the switching device further comprises - a second auxiliary circuit (S2) for generating the second signal, which is inversely proportional to the input voltage. In this way it is achieved that the switching device is suitable for operating the lamp at a voltage with a constant effective value.</p> |
