Abstract: Disclosed is a circuit arrangement for supplying a lamp wattage to a high-pressure discharge lamp (Lp) in the form of an alternating current having an operating frequency. The alternating current is generated by a full bridge that is composed of two half-bridge branches. The lamp wattage can be adjusted via the phase which the two half-bridge branches have relative to each other. The lamp wattage is modulated by means of the transmission function of an interface if the operating frequency is frequency-modulated. Said modulation of the lamp wattage can be compensated by adequately correcting the phase.

Abstract: In the case of an apparatus for providing a sinusoidally amplitude-modulated operating voltage, two switches are arranged in the form of a half bridge, and an LC element is arranged downstream of the half bridge. The first switch is driven by a first square-wave signal in a clocking with the amplitude modulation frequency per clock cycle, and the second switch (QLOW) is driven by a second square-wave signal, which is shorter than the first signal, with a temporal offset with respect to the first signal in each clock cycle. The LC element (LMOD, CMOD) acts as a filter for the signal resulting from the driving of the switches at a connection point (K) between the switches and allows a DC voltage component and a sinusoidal component of the signal with the fundamental frequency of the clocking to pass through, but substantially filters out harmonics.

Abstract: A circuit arrangement for operating at least one high-pressure discharge lamp (16), has four switches (Q1 to Q4) in a full-bridge arrangement (14), a first and a second switch (Q1, Q2) forming the first half-bridge arm, and a third and a fourth switch (Q3, Q4) forming the second half-bridge arm, at least two terminals for coupling the high-pressure discharge lamp (16) between the midpoint of the first and the second half-bridge arms, at least two terminals for supplying the circuit arrangement (10) with a dc voltage signal and a drive circuit (20) for driving the four switches (Q1 to Q4). The drive circuit (20) is designed to provide drive signals, (z1(t), Z2(t), {overscore (z)}1(t), {overscore (z)}2(t)) for the four switches (Q1 to Q4), whose clock pulse (ft) is swept between a first and a second frequency, and whose pulse width and/or phase is modulated with a prescribable third frequency (fa).

Abstract: A ballast for at least one lamp at least two switches arranged in series; a control circuit for alternately opening and closing the two switches; a connection for applying a supply voltage to the two switches; a resonant starting circuit coupled on the input side to the junction point between the two switches and on the output side to a first connection for the lamp, the resonant starting circuit having a resonant inductance arranged in series with the junction point between the two switches (S1, S2) and the first connection for the lamp, and a resonant capacitance arranged for alternating current purposes in parallel with the first and second connections for the lamp, a first braking inductance which, for alternating current purposes, is firstly arranged in series with the first of the two connections for the lamp and secondly in parallel with the resonant capacitance.

Abstract: The operating method is based on the simultaneous application of FM and AM, and is distinguished by passing through three operating states, specifically a warm-up phase, an impressing phase and the continuous operation.

Abstract: Lighting system for high-pressure discharge lamps which can generate a lamp voltage UL which is amplitude and, if necessary, frequency-modulated. The frequency modulation is provided by an inverter whose inverter frequency is modulated. The inverter is fed by a clocked d.c. voltage supply which emits an operating voltage U0 which is amplitude-modulated.