Abstract: A luminescent material is dispersed in a watery solution of sodium polyphosphate, a watery solution of a nitrate of the metal M is added, after which the luminescent material is separated, dried and fired. The metal is chosen from the group consisting of Ca, Sr, and Ba, whereby a protective layer of metal polyphosphate is formed on the luminescent material.

Abstract: A low-pressure mercury-vapor discharge lamp is provided with a discharge vessel and a first and a second end portion (12a). The discharge vessel encloses a discharge space provided with a filling of mercury and an inert gas in a gastight manner. Each end portion (12a) supports an electrode (20a) arranged in the discharge space. An electrode shield (22a) encompasses at least one of the electrodes (20a) and is made from a ceramic material. Preferably, the electrode shield (22a) is tubular in shape with a lateral slit directed towards the discharge space. The lamp according to the invention has a comparatively low mercury consumption.

Abstract: A low-pressure mercury-vapor discharge lamp is provided with a discharge vessel and a first and a second end portion (12a). The discharge vessel encloses a discharge space provided with a filling of mercury and an inert gas in a gastight manner. Each end portion (12a) supports an electrode (20a) arranged in the discharge space. An electrode shield (22a) encompasses at least one of the electrodes (20a) and is made from a ceramic material. Preferably, the electrode shield (22a) is tubular in shape with a lateral slit directed towards the discharge space.

Abstract: A low-pressure mercury vapor discharge lamp is provided with a discharge vessel and a first and a second end portion (12a). The discharge vessel encloses a discharge space provided with a filling of mercury and a rare gas in a gastight manner. Each end portion (12a) supports an electrode (20a) arranged in the discharge space. An electrode shield (22a) encompasses the electrodes (20a) and is covered with a material which reacts with or forms an alloy with alkaline earth metals, which material is released by the electrode (20a).

Abstract: A lighting system includes at least two light-emitting diodes each emitting, in operation, visible light in a preselected wavelength range. A converter converts part of the visible light emitted by one of the diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system. The diodes include a blue light-emitting diode and a red light-emitting diode. Further, the converter includes a luminescent material for converting a portion of the light emitted by the blue light-emitting diode into green light.

Abstract: As a white light source, the lighting system (1) has at least three light-emitting diodes (6, 7, 8) for providing visible light at preselected wavelengths. The invention is characterized in that the lighting system (1) is provided with at least one fourth light-emitting diode (9) which, in operation, emits visible light in a further wavelength region, the maximum of the spectral emission of the fourth light-emitting diode (9) lying in the further wavelength region from 575 to 605 nm. Preferably, the further wavelength region ranges from 585 to 600 nm. Preferably, the color rendition of the lighting system (1) is above 60. Preferably, the luminous efficacy of the lighting system (1) is above 30 lm/W, preferably above 40 lm/W. In another preferred embodiment, the color temperature of the lighting system (1) can be adjusted by selectively switching the light-emitting diodes (6, 7, 8, 9).

Abstract: A lamp vessel is made from a material which absorbs short-wave UV radiation. In addition, the luminescent screen comprises cerium-activated lunthanum phosphate and a luminescent substance having an emission band whose maximum is situated in the wavelength range from 340 nm and whose half-value ranges between 35 nm and 80 nm. The emission spectrum of the lamp for wavelengths below 400 nm corresponds closely to the solar spectrum while the lamp also has a high erythema L light output.

Abstract: The invention relates to a luminescent material of general formula (BaxSr1−x−yPby)2Mg(BO3)2 wherein 0≦x≦0.999, 0.0005<y<0.05. Luminescent materials of this general formula are very suitable for use in low pressure mercury discharge lamps for tanning purposes.

Abstract: A luminescent material coated with a crystalline layer of a metal oxide M.sub.2 O.sub.3 wherein a metal M is chosen from the group formed by Y and Al is shown. According to this method the luminescent material is first introduced into a solution of a salt of the metal M, then a compound of the metal M is deposited on the luminescent material through homogeneous precipitation, and subsequently the luminescent material is separated from the solution, dried, and heated. It is achieved thereby that the luminescent material will absorb mercury to a low degree only, and that accordingly the color point of a low-pressure mercury discharge lamp whose luminescent layer comprises a luminescent material coated in accordance with the invention only shows a small shift as the lamp ages.

Abstract: A low-pressure mercury discharge lamp having emission maxima in three spectral regions, provided with a gastight, radiation-transmitting discharge vessel with a gas filling comprising mercury and rare gas. A luminescent layer comprises at least a first luminescent material with an emission maximum in the 590-630 nm region and a second luminescent material with an emission maximum in the 520-565 nm region. The first luminescent material contains a compound defined by the formulaM1.sub.x M2.sub.(1-x-y)BO.sub.3 : Eu.sup.+3.sub.y,in which M1 is selected from the group consisting of Sc, In and Lu, and M2 is selected from the group consisting of Sc, Y, La, Gd, Ga, In and Lu, in which M1 differs from M2, in which x.gtoreq.0 and 0.01.ltoreq.y.ltoreq.0.2, and in which the compound has the calcite lattice structure.

Abstract: A visible light emitting device for use in lighting and/or display applications includes a UV LED, a phosphor layer on the upper, main light emitting surface of the LED, and a short wave pass (SWP) filter between the LED and the phosphor layer to transmit UV light from the LED to the phosphor layer, as well as to reflect visible light from the phosphor layer in a forward direction, thus enhancing the efficiency of the device. Additional optical filters located on the top of the phosphor layer further enhance efficiency and/or spectral characteristics of the emitted light.

Abstract: The invention relates to a method of coating a luminescent material with a layer of a metal oxide M.sub.2 O.sub.3 wherein a metal M is chosen from the group formed by Y and Al. The invention also relates to a coated luminescent material and to a low-pressure mercury discharge lamp.According to the invention, the luminescent material is first introduced into a solution of a salt of the metal M, then a compound of the metal M is deposited on the luminescent material through homogeneous precipitation, and subsequently the luminescent material is separated from the solution, dried, and heated.It is achieved thereby that the luminescent material will absorb mercury to a low degree only, and that accordingly the color point of a low-pressure mercury discharge lamp whose luminescent layer comprises a luminescent material coated in accordance with the invention only shows a small shift as the lamp ages.

Abstract: Blue-luminescing lanthanum-gadolinium-oxybromide, activated by trivalent cerium, which oxybromide is also activated by trivalent terbium and is defined by the molecular formulaLa.sub.1-x-y-z Gd.sub.x Ce.sub.y Tb.sub.z OBr,in which0.25.ltoreq.x.ltoreq.1-y-z,0.002.ltoreq.y.ltoreq.0.05,0.0001.ltoreq.z.ltoreq.0.005 and y.ltoreq.z.