Abstract: 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.

Abstract: A lighting unit includes a discharge vessel having a wall provided with a first luminescent layer, a gas fill consisting essentially of neon at a pressure less than 30 mbar, and a means for providing a constant DC current for exciting the fill in the discharge vessel to emit UV light for exciting the luminescent layer. DC operation offers substantially higher luminous flux over AC operation. The lighting unit may further include a housing having a reflective surface, a second luminescent layer, and a filter incorporated within the discharge vessel.

Abstract: An arrangement including a frequency converter (4) and a discharge lamp (10) connected thereto wherein the frequency converter (4) is of a type whose output frequency is at least 80 kHz, while the lamp is a low-pressure sodium vapor discharge lamp. This lamp supply system provides a high luminous efficacy for the lamp.