Abstract: A light-emitting semiconductor device includes a stack of layers including an active region. The active region includes a semiconductor selected from the group consisting of III-Phosphides, III-Arsenides, and alloys thereof. A superstrate substantially transparent to light emitted by the active region is disposed on a first side of the stack. First and second electrical contacts electrically coupled to apply a voltage across the active region are disposed on a second side of the stack opposite to the first side. In some embodiments, a larger fraction of light emitted by the active region exits the stack through the first side than through the second side. Consequently, the light-emitting semiconductor device may be advantageously mounted as a flip chip to a submount, for example.

Abstract: In a lighting arrangement comprising a LED array and a DC-DC-converter for supplying the LED array, the DC-DC-converter is an up-converter and the LED array is coupled between an input terminal and an output terminal. The up-converter generates a very low voltage over the LED array without making use of a transformer.

Abstract: A color, transmissive LCD is described herein which uses red, green, and blue LEDs as the light source. The R, G, and B LEDs are coupled to separate light guides, one light guide for each color. These light guides may take the form of three overlying plastic or glass sheets. In another embodiment, thin fiber optic cables arranged parallel to each other on a supporting surface are used as the light guides, and each fiber optic cable is optically coupled to only one R, G, or B LED in a repeating pattern. The light guides contain deformities to emit light coinciding with the positions of the red, green, and blue pixels. The R, G, and B LEDs are constantly on, and there is no color filtering.

Abstract: In a circuit arrangement for driving a LED array comprising red, green and blue LEDs, a control loop is added for limiting the duty cycles of the control signals for driving the red, green and blue LEDs. In case one of the duty cycles reaches the limit value, the reference signals for the red, green and blue light are decreased with the same relative amount. The color point of the light is thereby maintained, even when the efficiency of part of the LEDs decreases.

Abstract: A method of forming a photoresist mask on a light emitting device is disclosed. A portion of the light emitting device is coated with photoresist. A portion of the photoresist is exposed by light impinging on the interface of the light emitting device and the photoresist from inside the light emitting device. The photoresist is developed, removing either the exposed photoresist or the unexposed photoresist. In one embodiment, the photoresist mask may be used to form a phosphor coating. After the photoresist is developed to remove the exposed photoresist, a phosphor layer is deposited overlying the light emitting device. The unexposed portion of photoresist is stripped. In some embodiments, the light exposing the photoresist is produced by electrically biasing the light emitting device, or by shining light into the light emitting device through an aperture or by a focussed laser.

Abstract: A light emitting device includes a semiconductor light emitting device chip having a top surface and a side surface, a wavelength-converting material overlying at least a portion of the top surface and the side surface of the chip, and a filter material overlying the wavelength-converting material. The chip is capable of emitting light of a first wavelength, the wavelength-converting material is capable of absorbing light of the first wavelength and emitting light of a second wavelength, and the filter material is capable of absorbing light of the first wavelength. In other embodiments, a light emitting device includes a filter material capable of reflecting light of a first wavelength and transmitting light of a second wavelength.

Abstract: In an up-converter feed forward control of the output current is effected by rendering the conduction time of the switching element proportional to Vout/Vin2. This control is fast and avoids interference and loss of efficiency.

Abstract: The amount of usefully captured light in an optical system may be increased by concentrating light in a region where it can be collected by the optical system. A light emitting device may include a substrate and a plurality of semiconductor layers. In some embodiments, a reflective material overlies a portion of the substrate and has an opening through which light exits the device. In some embodiments, reflective material overlies a portion of a surface of the semiconductor layers and has an opening through which light exits the device. In some embodiments, a light emitting device includes a transparent member with a first surface and an exit surface. At least one light emitting diode is disposed on the first surface. The transparent member is shaped such that light emitted from the light emitting diode is directed toward the exit surface.

Abstract: The amount of usefully captured light in an optical system may be increased by concentrating light in a region where it can be collected by the optical system. A light emitting device may include a substrate and a plurality of semiconductor layers. In some embodiments, a reflective material overlies a portion of the substrate and has an opening through which light exits the device. In some embodiments, reflective material overlies a portion of a surface of the semiconductor layers and has an opening through which light exits the device. In some embodiments, a light emitting device includes a transparent member with a first surface and an exit surface. At least one light emitting diode is disposed on the first surface. The transparent member is shaped such that light emitted from the light emitting diode is directed toward the exit surface.

Abstract: A device includes a semiconductor light emitting device and a wavelength-converting material comprising Sr—SiON:Eu2+. The Sr—SiON:Eu2+ wavelength-converting material absorbs light emitted by the light emitting device and emits light of a longer wavelength. The Sr—SiON:Eu2+ wavelength-converting material may be combined with other wavelength-converting materials to make white light. In some embodiments, the Sr—SiON:Eu2+ wavelength-converting layer is combined with a red-emitting wavelength-converting layer and a blue light emitting device to generate emission in colors, which are not achievable by only mixing primary and secondary wavelengths. In some embodiments, the Sr—SiON:Eu2+ wavelength-converting layer is combined with a red-emitting wavelength-converting layer, a blue-emitting wavelength-converting layer, and a UV light emitting device.

Abstract: A backlight for an LCD uses as a light source at least one red light source, at lest one green light source, at least one blue light source, wherein one of the sources comprises a light emitting diode capable of emitting light at a first wavelength and a wavelength-converting material capable of absorbing light of the first wavelength and emitting light of a second wavelenght. In some embodiments, the wavelength-converting material is a strontium thiogallate phosphor or a nitridosilicate phosphor. In some embodiments, the first wavelength is about the same as light emitted by the blue light source, or is barely visible to the human eye.

Abstract: A light emitting device includes a semiconductor light emitting device chip having a top surface and a side surface, a wavelength-converting material overlying at least a portion of the top surface and the side surface of the chip, and a filter material overlying the wavelength-converting material. The chip is capable of emitting light of a first wavelength, the wavelength-converting material is capable of absorbing light of the first wavelength and emitting light of a second wavelength, and the filter material is capable of absorbing light of the first wavelength. In other embodiments, a light emitting device includes a filter material capable of reflecting light of a first wavelength and transmitting light of a second wavelength.

Abstract: The present invention provides a phosphor-converted LED device comprising one or more phosphor thin films that convert primary light emitted by the LED into one or more other wavelengths of light to produce light of a particular color. Each phosphor thin film comprises dopant ions that are statistically spatially distributed in such a manner that the phosphor conversion of the primary light is predictable and controlled by the concentration of the dopants and by the thickness of the thin film. Therefore, variations in the color of the light produced by phosphor-converted LED devices can be eliminated, thereby enabling uniformity in the quality of the colored light produced to be ensured. In accordance with one embodiment of the present invention, a single phosphor thin film is comprised by the LED device. The thin film converts a portion of the primary emission into yellow light while allowing a portion of the primary blue light to pass through the thin film.

Abstract: A LED is covered with an electroconductive layer, and a luminescent layer is deposited on the electroconductive layer by electrophoresis. The conductivity of the electroconductive layer is chosen to be such that the layer can be used as one of the electrodes during the electrophoresis, while the LED is not short-circuited by the electroconductive layer during normal operation.

Abstract: The present invention relates to a tri-color lamp for generating white light. In particular, the invention relates to a phosphor mixture comprising two phosphors having host sulfide materials that can absorb radiation emitted by a light emitting diode, particularly a blue LED. This arrangement provides a mixing of three light sources—light emitted from the two phosphors and unabsorbed light emitted from the LED. The phosphors can contain the same dopant, such as a rare earth ion, to allow matching of the phosphors in relation to the LED emitted radiation. Power fractions of each of the light sources can be varied to achieve good color rendering. The present invention also relates to an alternative to a green LED comprising a single green phosphor that absorbs radiation from a blue LED. A resulting device provides green light of high absorption efficiency and high luminous equivalent values.

Abstract: A light emitting device including a nucleation layer containing aluminum is disclosed. The thickness and aluminum composition of the nucleation layer are selected to match the index of refraction of the substrate and device layers, such that 90% of light from the device layers incident on the nucleation layer is extracted into the substrate. In some embodiments, the nucleation layer is AlGaN with a thickness between about 1000 and about 1200 angstroms and an aluminum composition between about 2% and about 8%. In some embodiments, the nucleation layer is formed over a surface of a wurtzite substrate that is miscut from the c-plane of the substrate. In some embodiments, the nucleation layer is formed at high temperature, for example between 900° and 1200° C. In some embodiments, the nucleation layer is doped with Si to a concentration between about 3e18 cm−3 and about 5e19 cm−3.

Abstract: A light emitting device comprises a light emitting diode that emits primary light and a SrGa2S4:Eu2+ phosphor material capable of absorbing at least a portion of the primary light and emitting secondary light. The secondary light includes a wavelength longer than a wavelength of the primary light.

Abstract: A light emitting device includes a light source that emits first light in response to an electrical signal, and a fluorescent layer positioned over the light source. The fluorescent layer includes a first fluorescent material which radiates second light and a second fluorescent material which radiates third light. In one embodiment, the second fluorescent material contains europium activated calcium sulfide. In another embodiment, the second fluorescent material contains europium activated nitrido-silicate. In some embodiments, the device includes a light propagation medium which transmits the first, second, and third light as composite output.

Abstract: A lens comprises a bottom surface, a reflecting surface, a first refracting surface obliquely angled with respect to a central axis of the lens, and a second refracting surface extending as a smooth curve from the bottom surface to the first refracting surface. Light entering the lens through the bottom surface and directly incident on the reflecting surface is reflected from the reflecting surface to the first refracting surface and refracted by the first refracting surface to exit the lens in a direction substantially perpendicular to the central axis of the lens. Light entering the lens through the bottom surface and directly incident on the second refracting surface is refracted by the second refracting surface to exit the lens in a direction substantially perpendicular to the central axis of the lens. The lens may be advantageously employed with LEDs, for example, to provide side-emitting light-emitting devices. A lens cap attachable to a lens is also provided.

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.