U.S. Philips Corporation

U.S. Phillips Corporation

Lukas Kastelein

Johannes T De Hair

Petrus Cornelis Lauwerijssen

Henricus C Verhaar

A low-pressure mercury discharge lamp with a lamp vessel having a first lamp vessel portion (La1) with a first electrode (E11) and a first luminescent layer which radiates white light of a first color temperature during lamp operation and a second lamp vessel portion (La2) with a second electrode (E12) and with a second luminescent layer which radiates white light of a second colour temperature different from the first during lamp operation. The first lamp vessel portion and the second lamp vessel portion are interconnected by a connection which allows a filling of mercury and a rare gas in both portions to pass and together enclose a discharge space. The discharge space contains only one further electrode (E13) for both the first and second lamp vessel portions. Circuit I generates a first current through the first lamp vessel portion and a second current through the second lamp vessel portion and circuit II adjusts the ratio between the effective value of the first current and the effective value of the second current. The first current and the second current are high-frequency currents of changing polarity. The color temperature of the light radiated by the lamp can be adjusted over a comparatively wide range, while the lamp is of a simple construction and has a comparatively high luminous efficacy.

Low-pressure mercury discharge lamp with color temperature adjustment

A method of selecting low-pressure mercury discharge lamps comprising a luminescent layer, the luminescent layer being excited and the low-pressure mercury discharge lamps being selected in dependence on the emission spectrum of the visible light emitted by the luminescent layer. The luminescent layer is excited by a light source arranged outside the low-pressure mercury discharge lamp and which generates ultraviolet radiation having a wavelength above 300 nm. This makes it possible to use the presence of a blue-luminescent substance in the luminescent layer as a selection criterion for both leaky and intact low-pressure mercury discharge lamps.

Method and device for selecting low-pressure murcury discharge lamps

A circuit arrangement and a method suitable for operating a low-pressure mercury discharge lamp which includes circuitry for adjusting the average amplitude of the current provided to the lamp as well as circuitry for adjusting the modulation of the current provided to the lamp.

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Roosendaal, Netherlands

Lukas Kastelein