Abstract: One or more LEDs are mounted within an LCD without the use of any printed circuit board (PCB), thus reducing the thickness of the LCD by about the thickness of the conventional PCB. In one embodiment, the LED and submount are mounted so that the submount is opposing the liquid crystal layer side of the LCD, so that the liquid crystal layers provide the mechanical support for the submount and LED die. The LED die (mounted on the submount) may be inserted into a cavity formed in the “top” surface of the light guide, and the top surface of the light guide is abutted against the liquid crystal layers. In such a configuration, the LED light source, including all supporting components, adds no thickness to the LCD. In another embodiment, on the “bottom” surface of the LCD opposing the LED die is an electrically switchable mirror that is either reflective or transparent. In its transparent state, the LED in the LCD may be used as a flash in a cell phone camera, while the LCD may be viewed to take the picture.

Abstract: Various embodiments of corner-coupled backlights are described, where one or more LEDs are optically coupled to a truncated corner of a solid rectangular light guide backlight. In one embodiment, a high-power, white light LED is mounted in a small reflective cavity, which is then coupled to a flattened corner of the light guide. The reflective cavity provides a more uniform light distribution at a wide variety of angles to the face of the truncated corner to better distribute light throughout the entire light guide volume. This creates a more uniform light guide emission into the liquid crystal layers. In other embodiments, an LED is mounted in a small cavity near a corner of the light guide, and a reflector is mounted on the corner of the light guide. Various techniques for removing heat from the LED without adding additional area requirements are also disclosed.

Abstract: For mixing different light colors from different LEDs or energized phosphors, an elongated mixing tunnel is used having a reflective inner surface. LEDs of different colors are optically coupled along the length of the mixing tunnel and at a first end of the tunnel. Light coupled along the length of the tunnel is reflected by an angled dichroic mirror that selectively reflects the incoming color light towards a single output port of the mixing tunnel. The dichroic mirror passes all other colors of light being transmitted towards the output port of the tunnel. Two, three, or more colors of LEDs can be used. Efficient and compact ways to energize phosphors are also described. Other optical techniques are also described.

Abstract: A device includes a light emitting semiconductor device bonded to an optical element. In some embodiments, the optical element may be elongated or shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element. In some embodiments, the semiconductor light emitting device and optical element are positioned in a reflector or adjacent to a light guide. The optical element may be bonded to the first semiconductor light emitting device by a bond at an interface disposed between the optical element and the semiconductor light emitting device. In some embodiments, the bond is substantially free of organic-based adhesives.

Abstract: Low profile, side-emitting LEDs are described, where all light is efficiently emitted within a relatively narrow angle generally parallel to the surface of the light-generating active layer. The LEDs enable the creation of very thin backlights for backlighting an LCD. In one embodiment, the LED is a flip chip with the n and p electrodes on the same side of the LED, and the LED is mounted electrode-side down on a submount. A reflector is provided on the top surface of the LED so that light impinging on the reflector is reflected back toward the active layer and eventually exits through a side surface of the LED. A waveguide layer and/or one or more phosphors layers are deposed between the semiconductor layers and the reflector for increasing the side emission area for increased efficiency. Side-emitting LEDs with a thickness of between 0.2-0.4 mm can be created.

Abstract: A light emitting device includes a light source that produces light having a range of wavelengths and an angular dependent element that filters the light. The angular dependent element, may be, e.g., a dichroic filter, dichroic mirror, a cholesteric film, a diffractive filter, and a holographic filter. The angular dependent element having one or more ranges in which wavelengths of light are more efficiently propagated than wavelengths of light that are not within the one or more ranges. The angular dependent element is positioned at an angle with respect to the optical axis. By adjusting the angular position of the angular dependent filter with respect to the optical axis, the wavelengths of light produced by the light emitting device can be controlled to select a desired color of light.

Abstract: A device includes a light emitting semiconductor device bonded to an optical element. In some embodiments, the optical element may be elongated or shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element. In some embodiments, the semiconductor light emitting device and optical element are positioned in a reflector or adjacent to a light guide. The optical element may be bonded to the first semiconductor light emitting device by a bond at an interface disposed between the optical element and the semiconductor light emitting device. In some embodiments, the bond is substantially free of organic-based adhesives.

Abstract: A white light LED for use in backlighting or otherwise illuminating an LCD is described where the white light LED comprises a blue LED over which is affixed a preformed red phosphor platelet and a preformed green phosphor platelet. In one embodiment, to form a platelet, a controlled amount of phosphor powder is placed in a mold and heated under pressure to sinter the grains together. The platelet can be made very smooth on all surfaces. A UV LED may also be used in conjunction with red, green, and blue phosphor plates. The LED dies vary in color and brightness and are binned in accordance with their light output characteristics. Phosphor plates with different characteristics are matched to the binned LEDs to create white light LEDs with a consistent white point for use in backlights for liquid crystal displays.

Abstract: Various optical techniques are described for obtaining a specified light output from an LED source. One technique uses a parabolic reflector surrounding an LED or LED array to create a collimated beam, and the light exit opening of the parabolic reflector is defined by a reflective disc with an opening of the desired size. Any generated light that is outside of the opening is reflected back into the parabolic reflector and re-reflected until the light exits the opening. For mixing different light colors from different LEDs or energized phosphors, a mixing tunnel is used. The mixing tunnel includes angled dichroic mirrors or angled polarizer mirrors that selectively reflect and pass selected colors or polarizations of light to a single output port of the mixing tunnel. Efficient and compact ways to energize phosphors are also described. Other optical techniques are also described.

Abstract: In an LCD, a backlight having red, green, and blue LEDs is controlled to generate monochromatic light (e,g., blue) during a portion of a cycle, such as an image frame cycle. During another portion of the cycle, all the LEDs are illuminated to create white light. The color filter in the LCD panel contains, for each white pixel, a first color (e.g., red) subpixel filter, a second color (e.g., green) subpixel filter, and a clear subpixel area for passing white light and the monochromatic. The liquid crystal layer shutters are controlled to pass from 0-100% of the light for their associated subpixels to create a color image. With proper control of the shutters, any desired color of each white pixel can be achieved during the cycle. By converting one color filter to a clear area, the transmission efficiency of the display is greatly increased.

Abstract: The invention provides a light-emitting device and a method of illumination. The light-emitting device includes one or more semiconductor layers, a reflective bottom surface, and a top surface coupled to semiconductor layer. The semiconductor layers include an active region where a primary light is generated. The relative position of the top surface, the reflective bottom surface and the active region is adjusted to substantially transmit the primary light through the sides of the light-emitting device.

Abstract: A compact illumination system that is suitable for, e.g., projection systems, includes a plurality of light emitting diodes that are aligned along the same axis. The illumination system includes mirrors and a filter system for combining the light emitted by the different light emitting diodes. The light emitting diodes may be mounted within the same plane, e.g., on the same heatsink, which simplifies assembly and alignment of the system. Moreover, a collimator system with integrally formed refractive and/or reflective collimators, may be used. The use of an integrally formed collimator system advantageously reduces the number of piece parts and simplifies assembly.

Abstract: The invention provides an illumination system and a method for illumination. The illumination system includes one or more light sources that produce a primary light, a light-mixing zone that homogenizes the primary light, a wavelength-converting layer that converts the primary light to a secondary light, and a light-transmitting zone that receives the secondary light and transmits the secondary light to, for example, a Liquid Crystal Display (LCD).

Abstract: A light emitting device includes a light emitting element, an optical concentrator, such as a compound parabolic concentrator, a dichroic filter between the light emitting element and the optical concentrator and a wavelength converting material, such as a phosphor. The optical concentrator receives light from the light emitting element, via the dichroic filter, and emits the light from an exit surface, which is smaller than the entrance surface. The optical concentrator may be manufactured from a material with a high refractive index, such as sapphire. The wavelength converting material is, e.g., disposed over the exit surface. The radiance of the wavelength converting material is increased by pumping the wavelength converting material through a high index of refraction material and outputting the converted light into a low refractive index medium, such as air.

Abstract: A system for purifying a fluid uses ultra violet (UV) light to inactivate micro-organisms present in the fluid. The system has an arrangement of UV light emitters on perforated plates. The fluid, while passing through perforations in the perforated plates, is exposed to the UV light emitted by the UV light emitters. Micro-organisms present in the fluid pass very close to the UV light emitters. The UV light absorbed by the micro-organisms causes genetic damage and inactivation. The system has feedback units providing feedback about the physical properties of the fluid to a power unit supplying power to the UV light emitters. The power unit varies the amount of power supplied to the UV light emitters, based on the feedback.

Abstract: Various optical techniques are described for obtaining a specified light output from an LED source. One technique uses a parabolic reflector surrounding an LED or LED array to create a collimated beam, and the light exit opening of the parabolic reflector is defined by a reflective disc with an opening of the desired size. Any generated light that is outside of the opening is reflected back into the parabolic reflector and re-reflected until the light exits the opening. For mixing different light colors from different LEDs or energized phosphors, a mixing tunnel is used. The mixing tunnel includes angled dichroic mirrors or angled polarizer mirrors that selectively reflect and pass selected colors or polarizations of light to a single output port of the mixing tunnel. Efficient and compact ways to energize phosphors are also described. Other optical techniques are also described.

Abstract: An illumination device uses a wavelength converting element, such as a phosphor layer, that is physically separated from a light source, such as one or more light emitting diodes, a Xenon lamp or a Mercury lamp. The wavelength converting element is optically separated from the light source, so that the converted light emitted by the wavelength converting element is prevented from being incident on the light source. Accordingly, the temperature limitations of the wavelength converting element are removed, thereby permitting the light source to be driven with an increased current to produce a higher radiance. Moreover, by optically separating the wavelength converting element from the light source, the conversion and recycling efficiency of the device is improved, which also increases radiance.

Abstract: A device includes a light emitting semiconductor device bonded to an optical element. In some embodiments, the optical element may be elongated or shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element. In some embodiments, the semiconductor light emitting device and optical element are positioned in a reflector or adjacent to a light guide. The optical element may be bonded to the first semiconductor light emitting device by a bond at an interface disposed between the optical element and the semiconductor light emitting device. In some embodiments, the bond is substantially free of organic-based adhesives.

Abstract: One embodiment of the invention provides a backlight for an LCD display. The backlight uses a two-dimensional array of single color or white LEDs and a diffusing or phosphor coated cover plate. Various electrical connections of the LEDs and various phosphor color-conversion techniques are described.

Abstract: Lenses and certain fabrication techniques are described. A wide-emitting lens refracts light emitted by an LED die to cause a peak intensity to occur within 50-80 degrees off the center axis and an intensity along the center axis to be between 5% and 33% of the peak intensity. The lens is particularly useful in a LCD backlighting application. In one embodiment, the lens is affixed to the backplane on which the LED die is mounted and surrounds the LED die. The lens has a hollow portion that forms an air gap between the LED die and the lens, where the light is bent towards the sides both at the air gap interface and the outer lens surface interface. The lens may be a secondary lens surrounding an interior lens molded directly over the LED die.