| 摘要 |
The invention relates to a circuit arrangement for operating a lamp (LA), comprising means X for generating a current of alternating polarity, a load branch B coupled to the means X and provided with a series circuit Y comprising terminals (K1, K2) for holding the lamp, which terminals are connected by means of first capacitive means C1, and a current sensor SE means I coupled to current sensor SE and to the means X for controlling the power consumed by the lamp. According to the invention, the circuit arrangement in addition comprises a branch C which shunts the series circuit Y and which comprises a series arrangement of second capacitive means C2 and an impedance R2, the dimensioning of the circuit arrangement being chosen such that the ratio of the impedance value of the impedance R2 to the impedance value of current sensor SE is the same as the ratio of the amplitude of the current through the first capacitive means at least in one polarity direction to the amplitude of the current through branch C during lamp operation, and means II which form part of the means I and are coupled to current sensor SE and impedance R2 for generating a signal which is a measure for a difference between the voltage across current sensor SE and the voltage across impedance R2. This signal forms a comparatively accurate measure for the lamp current over a wide range of powers consumed by the lamp.
|
