| 摘要 |
The invention relates to a circuit arrangement for operating a discharge lamp (LA) by means of a high-frequency voltage, comprising: input terminals (K1, K2) for connection to a supply voltage source; means I (D1, L, S1, S2, T, C2, C3, C4) for generating the high-frequency voltage from a supply voltage delivered by the supply voltage source; means II for the substantially square-wave modulation of the amplitude of the high-frequency voltage, provided with means III for controlling the duty cycle of the square wave. According to the invention, the means III are provided with a measuring circuit for detecting the ignition of the discharge lamp during each cycle of the substantially square-wave modulation and with a timer circuit coupled to the measuring circuit for rendering the amplitude of the high-frequency voltage substantially equal to zero when a time interval has elapsed after the ignition of the discharge lamp. It is achieved thereby that the luminous flux of the discharge lamp fluctuates to a low degree only.
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