U.S. Philips Corporation

Adrianus J Berntsen

Coen T Liedenbaum

Jeroen J Vleggaar

Aemilianus G Staring

Martinus B Van Der Mark

Jeroen J Horikx

Robert J Demandt

Henri M Boots

Hermanus F Schoo

The illumination system (1) has a substrate (2) and an active layer (3) comprising an electroluminescent material, in which the active layer (3) is present between a first, optically transparent electrode layer (5) and a second electrode layer (7). The illumination system (1) is characterized in that a light-scattering layer (28) comprising a medium having light-scattering properties is present in a forward direction (29) with respect to the active layer (3), in which the non-scattered fraction of a (collimated) light beam, when passed through the light-scattering layer (8) in the forward direction (29), is in the range between 0.05 and 0.8, preferably in the range between 0.1 and 0.5. The light-scattering properties of the medium are preferably stronger as the light is more obliquely incident, as is achieved by using birefringent particles and/or media. A very suitable light-scattering layer (28) is a (half) monolayer of TiO.sub.2 particles provided on the substrate (2), with an average size of the (spherical) particles of 0.1-1 .mu.m. The light output of the illumination system (1) is further improved by providing the edges of the substrate (2) with a reflective coating (26).

Electroluminescent illumination system with an active layer of a medium

A description is given of a method of providing an electroluminescent device (20) comprising an active layer (5) of conjugated 2,5-alkyl- or alkoxy-substituted poly(p-phenylene vinylene) with inactive regions (51) and emissive regions (52) by means of patterned irradiation with UV light. Both regions (51) and (52) of the active layer (5) show a clear difference in electroluminescence, electrical resistance and solubility. By means of the above-described effects, displays can be manufactured without making use of structured electrode layers (3) and (11).

Electroluminescent device

Growing community of inventors

Eindhoven, Netherlands

Adrianus J Berntsen