U.S. Philips Corporation

U.S. Phillips Corporation

Henricus C Verhaar

Christianus J Roozekrans

Johannes T De Hair

Jan Willem Dorleijn

Dick Van Der Voort

Petrus Cornelis Lauwerijssen

Wilhelmus Mp Van Kemenade

Lukas Kastelein

Henriette J Talen-Van Der Mheen

A low-pressure mercury discharge lamp is provided with a discharge vessel (1) which encloses a discharge space (2) in a gastight manner and in which a filling including mercury is accommodated. The lamp is provided with means (3a, 3b) for maintaining an electric discharge in the discharge space. The discharge vessel is provided with a luminescent layer (5). The lamp generates light during operation with a spectrum which is substantially composed of radiation in a first wavelength region from 590 to 630 nm, a second wavelength region from 520 to 565 nm, and in a third wavelength region from 430 to 490 nm. The radiation in the wavelength interval from 590 to 600 nm accounts for at least 50% of the power of the radiation in the entire first wavelength region. A preferred embodiment of the lamp includes a luminescent material that complies with the formula M1.sub.x M2.sub.(1-x-y) BO.sub.3 :Eu.sup.3+.sub.y, in which M1 is an element from the group formed by Sc, In, and Lu, and in which M2 is an element from the group formed by Sc, Y, La, Gd, Ga, In, and Lu, where M1 is different from M2, with 0.01.ltoreq.y.ltoreq.0.2, x&gt;0, x+y&lt;1, while the luminescent material has a calcite lattice structure.

Low-pressure mercury discharge lamp with luminescent layer

A low-pressure mercury vapor discharge lamp according to the invention is provided with a discharge vessel having a tubular portion and a first and a second end portion. The discharge vessel encloses a discharge space provided with a filling of mercury and a rare gas in a gastight manner. Each end portion supports an electrode which is arranged in the discharge space. Current supply conductors extend from the electrodes through the end portions to outside the discharge vessel. The tubular portion of the discharge vessel is provided with a metal oxide layer on a surface which faces the discharge space. The first and the second end portion are also provided with metal oxide layers at surfaces which face the discharge space. The lamp according to the invention has a comparatively low mercury consumption.

Low-pressure mercury vapor discharge lamp

A low-pressure mercury vapour discharge lamp according to the invention comprises a radiation-transmitting, glass discharge vessel which encloses a discharge space in a gastight manner and which is provided with a filling of mercury and a rare gas. The lamp in addition comprises means for maintaining an electrical discharge in the discharge space. An intermediate layer which repels alkali metals and which is made of, for example, silicon oxide lies on a surface of the discharge vessel facing towards the discharge space, which intermediate layer supports a protective layer of at least an oxide of at least one element from the series formed by magnesium, aluminium, titanium, zirconium, and the rare earths, this protective layer being substantially free from particles greater than 1 .mu.m. The lamp according to the invention has a comparatively low mercury consumption.

Low-pressure mercury vapour discharge lamp

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.

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Eindhoven, Netherlands

Henricus C Verhaar