U.S. Philips Corporation

U.S. Phillips Corporation

Johannes T De Hair

Johannes T Van Kemenade

Everhardus G Berns

Lukas Kastelein

Robertus A Keijser

Petrus Cornelis Lauwerijssen

Henricus C Verhaar

Johannes H Van Der Sande

Monique M Eerdekens

Gert M Boogerd

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

The invention relates to a high-pressure sodium discharge lamp which under nominal operating conditions radiates white light with a maximum color rendering index R.sub.a of more than 80. Since the wall load is above 80 W/cm.sup.2 under nominal operating conditions, a color temperature T.sub.c of at least 2800.degree. K. can be achieved with a luminous efficacy of more than 40 lm/W.

High-pressure sodium discharge lamp having a color temperature of at

A low-pressure mercury vapor discharge lamp having a very satisfactory color rendition, (R(a,8).gtoreq.85), a color temperature of 2300-3300 K and a color point on or near the Planckian curve. The lamp is provided with a luminescent layer comprising:

Low-pressure mercury vapor discharge lamp

A low-pressure mercury vapor discharge lamp having a very satisfactory color rendition (R(a,8).gtoreq.85) and having a color temperature of at least 3200 K. and a color point located on or near the Planckian locus. The lamp is provided with a luminescent layer comprising:

A low-pressure mercury vapor discharge lamp having a satisfactory color rendition (Ra.gtoreq.80), a color temperature of 2800.degree. K. or higher and a color point on or near the Planckian locus. The lamp is provided with a luminescent layer (4) which comprises

Luminescent material having a host lattice comprising, as one of the main constituents, at least one of the elements Y, La and the lanthanides. The material is activated by Gd, and, in addition by one or more of the elements Pb, Tl, Sb, Pr and Bi and comprises one or more of the elements Mn, Tb, Eu, Dy and Sm and the third activator. These materials have an efficient emission originating from the third activator and are used in low-pressure mercury vapour discharge lamps.

Growing community of inventors

Eindhoven, Netherlands

Johannes T De Hair