U.S. Philips Corporation

Lambertus J Bouwman

Adrianus M De Bijl

Cornelis Johannes Janson

Guillaume M Hermes

Arjan Van Den Berg

Rolf E De Man

Johannes H Op Het Veld

Arjan J Van Den Berg

A DC/DC converter of the flyback/forward converter type includes a switch (S), a transformer (T), a first diode (D1), a first capacitor (C1), a second diode (D2) and a second capacitor (C2). The first and the second capacitor are arranged in series between the output terminals (K3, K4) of the DC/DC converter. The DC/DC converter has a high efficiency and is very suitable for operating a lamp with a DC current.

Circuit arrangement

A lampholder in accordance with the invention can suitably be used for a low-pressure discharge lamp (a) which operates at a high frequency and which comprises an elongated, tubular discharge vessel (b), said lamp being provided with a pair of electrodes (c, c') for maintaining an electric discharge in the discharge vessel. The lampholder (0) has contacts (1, 1') for connecting a high-frequency power supply (4), said contacts being electrically connected to a first (2) and a second terminal (2') for connecting the lamp. The second terminal is further removed from the contacts than the first terminal. A compensation conductor (6) extending between the first (2) and the second terminal (2') is connected to said first terminal (2). This leads to a reduction of conducted interference.

Lampholder and lighting unit comprising a lampholder

A circuit arrangement for supplying a discharge lamp with a direct current includes input terminals for connection to a supply voltage source. A circuit portion (I) is coupled to the input terminals for generating a DC voltage from the supply voltage and is provided with output terminals between which the DC voltage is present during operation. A first branch comprising a first capacitor interconnects the output terminals and a second branch comprising a series arrangement of a second capacitor and an impedance shunts the first branch. A load branch shunts the series arrangement and comprises terminals for connecting a discharge lamp. The second branch also includes a diode so that a discharge lamp operated by way of the circuit arrangement stabilizes satisfactorily after ignition by a current supplied by the second capacitor to the lamp via the impedance.

Ignition circuit for a discharge lamp

An electric lamp including a light source, a lamp cap having a shell and a base, a housing connected to the light source and to the lamp cap, and a ballast which is electrically connected to the light source for operating the light source and which is arranged at least partly in a space surrounded by the housing and the lamp cap. The lamp cap includes contacts electrically connected to the ballast at least during lamp operation, one of said contacts being provided on the base and a further one on the shell. The further contact is formed by a band of conducting material around the lamp cap, which band directly adjoins the base at one side and adjoins a band of insulating material around the lamp cap at another side. This suppresses the interference generated in the supply mains, due to capacitive coupling between the ballast and the further contact, to a considerable degree.

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Eindhoven, Netherlands

Lambertus J Bouwman