Abstract: A high-power LED lamp uses an LED chip that can be larger than 1 mm square. The chip has trenches that can convert light trapped in the semiconductor into light that passes through a major surface of the chip. The trenches include light-reflecting tracks joined to a chip terminal and feeding a semiconductor layer. The chip can have triangular light emitting elements that improve light extraction from the semiconductor. The elements can be fused, resulting in improved manufacture yield of chips. A 25 watt single chip lamp with a heat sink very close to the active region is described.

Abstract: A high-power LED lamp uses an LED chip that can be larger than 1mm square. The chip has trenches that can convert light trapped in the semiconductor into light that passes through a major surface of the chip. The trenches include light-reflecting tracks joined to a chip terminal and feeding a semiconductor layer. The chip can have triangular light emitting elements that improve light extraction from the semiconductor. The elements can be fused, resulting in improved manufacture yield of chips. A 25 watt single chip lamp with a heat sink very close to the active region is described.

Abstract: An LED color display matrix has first and second sets of LED lamps of first and second nominal color respectively. The actual colors of the lamps of the first set are not the same and this color mismatch is corrected for using the lamps of the second set.

Abstract: An LED light source for a lensed lamp is described. An LED chip sits in a hollow having a rectangular floor. A lower portion of the hollow has steep walls and accommodates the part of the chip that does not emit light. An upper part of the hollow has four side reflectors extending parallel to the sides of the chip and four corner reflectors. The hollow is formed by coining. The light source provides more uniform light than do previous arrangements having convergent lenses. The vertical viewing angle of the lamp is maintained throughout the whole of the horizontal viewing angle range of the lamp.

Abstract: A display matrix having LED lamps is arranged so that brightness variations between the lamps, due to the lamps having different characteristics from each other, is reduced. A process for setting up the display using an electronic camera is described. The system is arranged so that the brilliance of the lamps is automatically maximised when the sun is shining on the face of the display.

Abstract: An information display device includes a two-dimensional array of cells, each cell including an opaque wall pierced by an aperture and containing an opaque ferromagnetic spherical shutter member movable by electromagnetic means to roll upon a vertical wall of the cell between limiting positions in which it respectively exposes and occults the aperture. The shutter members may be restrained in their limiting positions by friction or magnets embedded in the cell walls.