U.S. Philips Corporation

Jacob Schlejen

Petrus H Antonis

Leonardus U Konings

Johannes Hendrik Wessels

Jozef R Bergervoet

Jeroen Peter Balm

Andrianus M De Bijl

An illumination unit comprises an electrodeless low-pressure discharge-lamp and a high-frequency power supply unit. The lamp has a gastight closed discharge vessel with an ionizable fill and a coil with turns of a primary and a secondary winding around a core of soft-magnetic material. The power supply unit has input terminals, a first output terminal, electrically neutral with respect to ground, that is connected to a first end of the primary winding, and a further output terminal that is connected to a second end of the primary winding. During nominal lamp operation the primary winding excites a high-frequency magnetic field that maintains an electrical discharge in the discharge vessel and that induces in the secondary winding a potential drop in the direction of a first, with respect to the electrically neutral end, to a second free end that varies in a sense opposite to the potential drop from the first to the second end in the first winding. At least one of the windings has at its second end at least one turn that extends beyond the core, which facilitates the ignition of the lamp.

Illumination unit, and electrodeless low-pressure discharge lamp and

An electrodeless low-pressure discharge lamp includes a translucent discharge-vessel of a glass that contains at least 5 weight % sodium, encloses a discharge-space and includes a mercury containing fill. The lamp further includes a device to maintain an electrical discharge in the discharge space and an auxiliary radiation source that emits at least 0.5 mW of visible radiation when activated, to provide a relatively short ignition time.

Electrodeless low-pressure discharge lamp

An illumination unit of the invention comprises an electrodeless low-pressure discharge-lamp (10) and a high-frequency power supply (50). The lamp (10) is provided with a gastight closed discharge vessel (20) with an ionizable fill (21). The lamp (10) further is provided with a coil (30) with turns (31,32) of a primary and a secondary winding (33,34). The power supply unit 50 is provided with input terminals (51a,51b) and is further provided with a first output terminal (52a), electrically neutral with respect to mass, that is connected to a first end (36a) of the primary winding (33) and with a further output terminal (52b) that is connected to a second end (36b) of the primary winding (33). During nominal operation of the lamp (10) the primary winding (33) excites a high-frequency magnetic field that maintains an electrical discharge in the discharge vessel (20) and that induces in the secondary winding (34) a potential drop in the direction of a first, with respect to the mass electrically neutral end (37a), to a second free end (37b) that varies in an opposite sense to the potential drop from the first to second end (36a, 36b) in the first winding (33). In a first end portion (39a) of the coil (30) that comprises half of the turns of the coil (30), the relative amount of turns (31) of the primary winding (33) is at least 3/2 times as large as the relative amount of turns (32) of the secondary winding (34). The measure of the invention improves the ignition speed of the lamp.

A circuit arrangement suitable for operating low-pressure mercury discharge lamp by means of a high-frequency current includes circuitry (I) for generating the high-frequency current from a supply voltage, and a modulator (II) for the substantially square-wave modulation of the amplitude of the high-frequency current at a modulation frequency f. The circuit arrangement is further provided with circuitry (V) for limiting the amplitude of the re-ignition voltage across the low-pressure mercury discharge lamp to a voltage Vi. As a result, interference with infrared systems caused by a discharge lamp operated by the circuit arrangement is substantially fully suppressed.

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Morgantown, WV, United States of America

Jacob Schlejen