| 摘要 |
The invention relates to a circuit arrangement suitable for operating a low-pressure mercury discharge lamp (IV) by means of a high-frequency pulsatory current, comprising circuitry (I) for generating the high-frequency pulsatory current from a supply voltage, a modulator (II) for the substantially sinusoidal amplitude modulation of the high-frequency pulsatory current with a modulation frequency f and a modulation depth M, and circuitry (III) for adjusting an amplitude A averaged over a modulation period of the substantially sinusoidal modulated high-frequency pulsatory current. According to the invention, the circuit arrangement is also provided with circuitry V for effecting a change in the substantially sinusoidal modulation. The latter circuitry renders it possible to limit to a great extent the shift in colour point of the light radiated by the lamp during dimming of the lamp. In addition, it is possible to adjust the colour point over a wide range for a given luminous flux of the lamp. <IMAGE> |
