Abstract: A backlight system comprises a light-emitting panel (1) having a front wall (2) and, opposite thereto, a rear wall (3), and opposite first and second light-transmitting edge surfaces (4; 5) associated with a plurality of first and second light sources (6; 7). Light originating from the light sources (6; 7) is diffused in the panel (1). Parts of the surface areas (8; 9) of the rear wall (3) are provided with extraction means (18, 18′, . . . ; 19, 19′, . . . ) for extracting light from the panel (1). First extraction means (18, 18′, . . . ) extract light from, preferably, the first light source (6), and vice versa In operation, said parts of the surface areas (8; 9) project light on a (LCD) display device panel (34) with an associated color filter (35). In the vicinity of the second edge area (5), the concentration of the first extraction means (18, 18′, . . . ) is higher than that of the second extraction means (19, 19′, . . . ), and vice versa.

Abstract: A circuit arrangement for operating a semiconductor light source includes connection terminals for connecting a control unit, an input filter, a converter comprising a control circuit, output terminals for connecting the semiconductor light source, an apparatus CM for removing a leakage current occurring in the control unit in the non-conducting state, and a self-regulating circuit for deactivating the apparatus CM. The circuit arrangement is also provided with a detection circuit for detecting an incorrect functioning of the converter or the semiconductor light source. For this purpose, preferably a minimum voltage and a maximum voltage are detected at the output terminals.

Abstract: Apparatus for mixing light from discrete LED light sources utilizes beam splitters which each have a semi-reflective layer which partially transmits and partially reflects light of any wavelength incident thereon. Each semi-reflective layer is situated in a transparent prismatic black between reflective surfaces on parallel outside faces of the block so that two parallel input beams are mixed and transmitted as two parallel mixed beams of like color. For a square array of light sources, a first mixing stage consists of two such prismatic blocks arranged side-by-side, and a second mixing stage consists of two such prismatic blocks arranged side-by-side and rotated 90 degrees to the first stage. The second stage is arranged to receive a square array of mixed beams and produces four identical output beams. The colors of the light sources are chosen so that all output beams are white.

Abstract: A circuit for operation of a semiconductor light source having terminals for connecting a source of power and output terminals for connecting the semiconductor light source. The circuit is also provided with a controlled current generator and is also concerned with a signal head incorporating the circuit. The controlled current generator is controlled by the current flow through the semiconductor light source and the current supplied by the controlled current generator.