Abstract: A circuit arrangement for igniting and operating a discharge lamp is provided with input terminals for connecting a supply source and a commutator having output terminals for connecting a lamp to be operated, the commutator including at least two switches which are alternately in a conducting and a non-conducting state. The commutator is suitable for pulse width modulation (PWM) operation of the switches. The switches and an output terminal are connected to one another by coupled inductors for this purpose.

Abstract: In an ignition circuit for a high-pressure discharge lamp having a pulse generating circuit in which ignition pulses are generated by a voltage-dependent breakdown element and a pulse transformer, a bandpass circuit has been inserted between the secondary winding of the pulse transformer and the discharge lamp. The bandpass filter is tuned to the fundamental frequency or a harmonic of the pulses generated by the pulse generation circuit.

Abstract: A circuit for operating a lamp includes supply input terminals for connection to a supply voltage source and a transformer provided with a primary winding L1 and a secondary winding L2. A first branch has terminals (N1,N2) for holding the lamp and connects a first end of the secondary winding L2 to a second end thereof. A second branch comprising a series circuit of a switching element (Q1) and the primary winding L1 interconnects the supply input terminals. A control circuit (SC1) is coupled to a control electrode of the switching element for generating a control signal for rendering the switching element conducting and non-conducting, and thus generating a first current in the primary winding L1 and a second current in the secondary winding L2. The second branch comprises a series arrangement of the primary winding, the switching element (Q1), and the terminals (N1,N2) for connection to the lamp. The total lamp current is controlled via the switching element which passes only a portion of the lamp current.

Abstract: The invention relates to a circuit arrangement for igniting a high-pressure discharge lamp (L), provided with input terminals (C,D) for connection to a commutating supply source with a square-wave supply voltage; a pulse-generating circuit (IV) provided with a voltage-dependent breakdown element (3) and with a voltage-raising network (2) formed by a network of rectifiers and capacitors; a pulse transformer (1); and an electrical connection between a secondary winding (12) of the pulse transformer and lamp connection terminals (E,F). The voltage-raising network (2) is in addition provided with inductors means (21, 22). The result of this is that a strongly increased voltage is available across the breakdown element substantially instantaneously after each commutation of the commutating supply voltage.

Abstract: A circuit arrangement (II) for igniting a high-pressure discharge lamp provided with a pulse transformer, a switching device and a capacitive element for a periodic charge inversion via the transformer and the switching device. The circuit arrangement is also provided with a peak current limiting impedance to protect the switching device. A voltage limiting device is added to the transformer. By the provision of the voltage limiting device, the lamp ignition is to a high degree made to be independent of lamp connection line impedances.

Abstract: A circuit arrangement for operating a discharge lamp with a substantially constant power P.sub.L by means of a switch mode power supply with a variable input current I.sub.o and provided with a periodically switching switching FET for controlling the variable input current by means of a drive signal. The drive signal is generated in a drive circuit (V) and is formed from a signal S1 which is proportional on the one hand to the input current and on the other hand to the lamp voltage V.sub.L and a reference signal. The circuit arrangement also includes a signal generator (IV) for generating the signal S1. The power P.sub.L to a good approximation thereby satisfies the relationP.sub.L =V.sub.b I.sub.o -K.sub.2 /V.sub.Lin which V.sub.b =supply source voltageV.sub.L =lamp voltageK.sub.2 =proportionality constant.