U.S. Philips Corporation

Ronny A Jacobs

Arnold Willem Buij

Johannes Hendrik Wessels

Alex P Van Den Bossche

A circuit arrangement for igniting and operating an electrodeless discharge lamp provided with a half-bridge commutator having two switching elements each having an emitter electrode and a control electrode and a parasitic capacitance in between. Each switching element is alternately switched to a conducting state by means of a resonant control circuit. The resonant control circuit is coupled to an oscillator by way of a transformer. The resonant circuit is provided with a capacitor which forms a part of the oscillator.

Bridge commutator with separate drive oscillator for electrodeless lamps

A circuit arrangement including a DC/AC converter for operating a discharge lamp. The DC/AC converter includes input terminals for connection of the DC/AC converter to a DC voltage source, and a switching circuit connected to the input terminals and provided with at least one switching element. The switching element has a control electrode and a main electrode and a control circuit between the main electrode and the control electrode for generating a control signal for the switching element. The switching element is conductive when a voltage is present between the control electrode and the main electrode with a first polarity having a value which exceeds a threshold value. A load branch includes at least inductive means and output terminals for connection of the discharge lamp, which load branch is supplied via the switching circuit. The control circuit also generates a DC voltage component between the control electrode and the main electrode with a polarity which is opposed to the first polarity. The switching element has fast switching capability including short duty cycles.

DC/AC converter for a discharge lamp having a DC offset at the switching

A circuit arrangement according to the invention for operating a discharge lamp (I) comprises a DC/AC converter (II) provided with a series circuit with a first and a second switching element, (1, 1', respectively) between a first and a second input terminal (5, 5', respectively) for connection to a DC voltage source, and with a starting circuit (F) with a first resistive means (R1) between the first input terminal (5) and the control electrode (2) of the first switching element (1). The DC/AC converter is also provided with a second resistive element (R2) which together with the first resistive element (R1) form a voltage divider between the input terminals (5, 5'). The power dissipation in the DC/AC converter is reduced thereby.

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Eindhoven, Netherlands

Ronny A Jacobs