The patent's assignee for patent number 8628255 is
News editors obtained the following quote from the background information supplied by the inventors: "The field of the invention is directed to Light Emitting Diode (LED) lighting/illumination systems/fixtures or luminaires. More specifically, the present embodiments are directed to LED lighting systems with phosphor, photo luminescent, wavelength conversion to generate a desired color of light.
"The introduction of solid state semiconductor devices such as semiconductor light emitting diodes (LEDs) has allowed a new generation of energy efficient lighting systems to come into existence. Today, most lighting fixture designs utilizing LEDs comprise systems in which an LED (or an LED array) replaces conventional system components such as incandescent bulbs, mercury vapor and compact fluorescent lamps. LEDs often further include a phosphor, photo luminescent material, whose light, emitted in response to excitation radiation from the LED in the system, combines with light from the LED to produce the lighting system's illumination product. It is common in such conventional systems to incorporate further elements such as a light reflection backplane, a light diffusing front plane, and color filter pigments and paints.
"U.S. Pat. No. 6,350,041 teaches a solid state lamp based on an LED which emits radially dispersed light for room illumination and other applications. The lamp comprises a solid state light source such as an LED or laser which transmits light through a separator to a disperser that disperses the light in a desired pattern and/or changes the color of light. In one embodiment, the light source comprises a blue emitting LED, the separator is a light pipe or fiber optic device and the disperser disperses the light radially and converts some of the blue light to yellow to produce a white light illumination product. The separator spaces the LED a sufficient distance from the disperser such that heat from the LED will not transfer to the disperser when the LED is carrying elevated currents as is necessary for room illumination. Such a lamp provides a solid state light source that can disperse light in many patterns, but is particularly applicable to a radial dispersion of white light for room illumination enabling the lamp to be used as an alternative light source in existing luminaires and lighting fixtures.
"While such lighting system designs may have demonstrated properties that are acceptable to some customers, properties such as intensity, color temperature and color perception, for instance, they lack flexibility in how the design components may be placed in the system. Phosphor layers are typically placed, for example, adjacent or in close approximation to a light emitting surface of the LED die/chip from whom they derive their excitation energy. Often, the phosphor layer must be coated directly onto the LED die to achieve the desired intensity and color of the illumination being generated.
"A need exists therefore for an improved illumination/lighting system based entirely on solid-state components, as before, but enhanced by providing greater flexibility in the placement of the components in the system."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "Embodiments of the present invention are directed to lighting systems comprising an excitation radiation source, which may for example be an LED or a laser diode, and a remotely located phosphor(s). Light from the excitation source is transported to the phosphor via a waveguiding medium and provides excitation radiation to the phosphor(s) and/or phosphor layer(s), causing a photo luminescence. The light from the phosphor(s) may comprise the final illumination product, or it may be combined with any visible light from the radiation source (which may occur, for example, in the case of a blue LED as the radiation source). The final illumination product may be white light, or any colored light. The presence of the waveguide transporting excitation radiation (and possibly the blue light component of the final illumination product) to the phosphor(s) allows greater flexibility in the design of the lighting system. Lighting system configurations allowed by the presence of the waveguide include for example hanging lighting fixtures/luminaires, desk lighting fixtures, table lamps, wall sconces, floor standing lamps, track lighting, spot lighting, accent lighting, inspection light, endoscope light and/or panel lighting. Typically, the distance the radiation travels from the excitation source to the phosphor layer is at least one centimeter in length though it may be typically be 10 cm or more. In some embodiments, the peak emission wavelength of the light emitted by the blue/UV LED is greater than about 300 nm, and the peak emission wavelength of at least one component of the photo luminescent light emitted by the phosphor is greater than about 430 nm.
"According to the invention a lighting system comprises: (a) an excitation source operable to generate excitation radiation; (b) a phosphor; and © a waveguide configured to guide the excitation radiation from the excitation source to the phosphor and wherein the configuration of the waveguide determines the configuration of the lighting system. The use of a waveguide enables new lighting system configurations and/or shapes to be fabricated since bulky components such as heat sinks, driver circuitry, and/or power converters can be located remote to the light emitting surface(s). To maximize light output a reflective surface can be provided on at least a part of at least one surface of the waveguide, the reflective surface being configured to reflect excitation radiation toward a light emitting surface of the waveguide. In one arrangement the distance the radiation travels from the excitation source to the phosphor layer is at least one centimeter in length, though it may typically travel 10, 50 or 100 cm in length.
"In one arrangement the excitation source comprises a light emitting diode which is advantageously operable to emit UV/blue light, excitation radiation.
"The waveguide can be configured to be in the shape of a lighting system such as a hanging lighting fixture, a desk lighting fixture, a floor standing lighting fixture, a desk lamp, track lighting, spot lighting, accent lighting or a lighting panel for incorporation into a suspended ceiling.
"In one arrangement the phosphor is coated in layer form on at least a part of a light emitting surface of the waveguide, for example an end surface of an elongate waveguide. Alternatively, the phosphor is embedded in particulate form in at least a portion of the waveguide medium. Moreover, the light emitting surface of the waveguide can further includes a surface topology to enhance emission of light from the surface such as a roughening of the surface or a regular pattern.
"The present invention finds particular application in lighting systems which produce a white light illumination product. The waveguide medium can comprise a glass, a plastics material such as acrylic or a polymeric resin.
"In one arrangement the peak emission wavelength of the light emitted by the excitation source is greater than about 300 nm, and the peak emission wavelength of at least one component of the photo luminescent light emitted by the phosphor is greater than about 430 nm. Preferably, the peak emission wavelength of the light emitted by the excitation source is in a range from about 300 to about 500 nm, and at least one component of the photo luminescent light emitted by the phosphor is greater than about 500 nm.
"To achieve a desired color of illumination product or color temperature the phosphor is a composition of at least two phosphors that emit light in the blue, green, yellow, orange, or red regions of the electromagnet spectrum.
"According to a further aspect of the invention a method of generating a product illumination comprises: (a) generating excitation radiation from an excitation source; (b) waveguiding the excitation radiation to a phosphor configured to photo lumines upon absorption of at least some of the excitation radiation; and © emitting waveguided excitation radiation from the excitation source and photo luminescent light from the phosphor as a combined product illumination.
"In one embodiment an endoscope lighting system comprises: (a) a light emitting diode operable to generate excitation radiation of a first wavelength; (b) a flexible fiber waveguide configured to guide the excitation radiation from the light emitting diode to a distal end of the fiber waveguide; and © a lens provided at the distal end of the waveguide, said lens incorporating a phosphor operable to emit light of a second wavelength in response to the excitation radiation.
"According to a further embodiment a lighting panel comprises: (a) a plurality of light emitting diodes operable to generate excitation radiation of a first wavelength; (b) a substantially planar waveguide having a light emitting face; © a phosphor provided over substantially the entire light emitting face and (d) a reflecting layer provided on at least the surface of the waveguide opposite the light emitting face, the lighting panel being configured such that excitation radiation from the light emitting diodes is coupled into at least one edge of the waveguide such as to propagate substantially throughout the waveguide and is then emitted through the light emitting face where at least a part of the excitation radiation excites the phosphor which emits light of a second wavelength. Preferably, the lighting panel is configured to fit an aperture of a suspended ceiling. The lighting panel can further comprise a heat sink around at least a part of the edged of the waveguide, the heat sink being in thermal communication with the plurality of light emitting diodes.
"According to a yet further embodiment a lighting system comprises: (a) at least one light emitting diode source operable to generate excitation radiation of a first wavelength; (b) a plurality of flexible optical fibers configured as a flexible sheet and each fiber having a phosphor on at least a part of its outer surface and © a flexible waveguide configured to couple excitation radiation from the excitation source to at least one end of each fiber such that the excitation radiation propagates substantially throughout the length of each fiber and is emitted through the light surface of each fiber and wherein at least a part of the excitation radiation excites the phosphor which emits light of a second wavelength. In one arrangement the fibers are woven as a flexible sheet and comprise the warp and/or weft of the sheet. Alternatively, the plurality of fibers can be mounted on a flexible backing material."
For additional information on this patent, see: Li, Yi-Qun. Light Emitting Diode Lighting System. U.S. Patent Number 8628255, filed
Keywords for this news article include: Electronics, Semiconductor, Light-emitting Diode,
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