US20070045640A1 - Light emitting devices for liquid crystal displays - Google Patents

Light emitting devices for liquid crystal displays Download PDF

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Publication number
US20070045640A1
US20070045640A1 US11/210,262 US21026205A US2007045640A1 US 20070045640 A1 US20070045640 A1 US 20070045640A1 US 21026205 A US21026205 A US 21026205A US 2007045640 A1 US2007045640 A1 US 2007045640A1
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United States
Prior art keywords
light emitting
layer
light
system
column
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/210,262
Inventor
Alexei Erchak
Michael Lim
Robert Karlicek
Michael Brown
Jo Venezia
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Rambus International Ltd
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Luminus Devices Inc
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Publication date
Application filed by Luminus Devices Inc filed Critical Luminus Devices Inc
Priority to US11/210,262 priority Critical patent/US20070045640A1/en
Assigned to LUMINUS DEVICES, INC. reassignment LUMINUS DEVICES, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BROWN, MICHAEL GREGORY, ERCHAK, ALEXEI A., KARLICEK, ROBERT F., JR., LIM, MICHAEL, VENEZIA, JO A.
Priority claimed from CN 200680015559 external-priority patent/CN101490604B/en
Publication of US20070045640A1 publication Critical patent/US20070045640A1/en
Assigned to RAMBUS INTERNATIONAL LTD. reassignment RAMBUS INTERNATIONAL LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: LUMINUS DEVICES, INC.
Application status is Abandoned legal-status Critical

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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/0001Light guides specially adapted for lighting devices or systems
    • G02B6/0011Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0068Arrangements of plural sources, e.g. multi-colour light sources
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00Nanooptics, e.g. quantum optics or photonic crystals
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/0001Light guides specially adapted for lighting devices or systems
    • G02B6/0011Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0018Redirecting means on the surface of the light guide
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/0001Light guides specially adapted for lighting devices or systems
    • G02B6/0011Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0028Light guide, e.g. taper
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/10Light guides of the optical waveguide type
    • G02B6/12Light guides of the optical waveguide type of the integrated circuit kind
    • G02B6/122Basic optical elements, e.g. light-guiding paths
    • G02B6/1225Basic optical elements, e.g. light-guiding paths comprising photonic band-gap structures or photonic lattices
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00Details of colour television systems
    • H04N9/12Picture reproducers
    • H04N9/31Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141Constructional details thereof
    • H04N9/315Modulator illumination systems
    • H04N9/3152Modulator illumination systems for shaping the light beam
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B6/00Light guides
    • G02B6/0001Light guides specially adapted for lighting devices or systems
    • G02B6/0011Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066Light guides specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0073Light emitting diode [LED]
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/491Disposition
    • H01L2224/4911Disposition the connectors being bonded to at least one common bonding area, e.g. daisy chain
    • H01L2224/49111Disposition the connectors being bonded to at least one common bonding area, e.g. daisy chain the connectors connecting two common bonding areas, e.g. Litz or braid wires
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/20Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
    • H01L33/22Roughened surfaces, e.g. at the interface between epitaxial layers
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/44Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

Light-emitting devices, and related components, processes, systems and methods are disclosed.

Description

    INCORPORATION BY REFERENCE
  • This application incorporates by reference the following U.S. Provisional Patent Applications: 60/462,889, filed Apr. 15, 2003; 60/474,199, filed May 29, 2003; 60/475,682, filed Jun. 4, 2003; 60/503,653, filed Sep. 17, 2003; 60/503,654 filed Sep. 17, 2003; 60/503,661, filed Sep. 17, 2003; 60/503,671, filed Sep. 17, 2003; 60/503,672, filed Sep. 17, 2003; 60/513,807, filed Oct. 23, 2003; 60/514,764, filed Oct. 27, 2003, 60/553,894, filed Mar. 16, 2004; 60/603,087, filed Aug. 20, 2004, 60/605,733, filed Aug. 31, 2004, 60/645,720 filed Jan. 21, 2005; 60/645,721 filed Jan. 21, 2005; 60/659,861 filed Mar. 8, 2005; 60/660,921 filed Mar. 11, 2005; 60/659,810 filed Mar. 8, 2005; and 60/659,811 filed Mar. 8, 2005. This application also incorporates by reference the following U.S. Patent Applications: U.S. Ser. No. 10/723,987 entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/724,004, entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/724,033, entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/724,006, entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/724,029, entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/724,015, entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/724,005, entitled “Light Emitting Devices,” and filed Nov. 26, 2003; U.S. Ser. No. 10/735,498, entitled “Light Emitting Systems,” and filed Dec. 12, 2003; U.S. Ser. No. 10/794,244, entitled “Light Emitting Device Methods” and filed Mar. 5, 2004; U.S. Ser. No. 10/794,452, entitled “Light Emitting Device Methods” and filed Mar. 5, 2004; U.S. Ser. No. 10/872,335, entitled “Optical Display Systems and Methods” and filed Jun. 18, 2004; U.S. Ser. No. 10/871,877, entitled “Electronic Device Contact Structures” and filed Jun. 18, 2004; and U.S. Ser. No. 10/872,336, entitled “Light Emitting Diode Systems” and filed Jun. 18, 2004.
  • TECHNICAL FIELD
  • The invention relates to light-emitting devices, and related components, processes, systems and methods.
  • BACKGROUND
  • A light emitting diode (LED) often can provide light in a more efficient manner than an incandescent light source and/or a fluorescent light source. The relatively high power efficiency associated with LEDs has created an interest in using LEDs to displace conventional light sources in a variety of lighting applications. For example, in some instances LEDs are being used as traffic lights and to illuminate cell phone keypads and displays.
  • Typically, an LED is formed of multiple layers, with at least some of the layers being formed of different materials. In general, the materials and thicknesses selected for the layers determine the wavelength(s) of light emitted by the LED. In addition, the chemical composition of the layers can be selected to try to isolate injected electrical charge carriers into regions (commonly referred to as quantum wells) for relatively efficient conversion to optical power. Generally, the layers on one side of the junction where a quantum well is grown are doped with donor atoms that result in high electron concentration (such layers are commonly referred to as n-type layers), and the layers on the opposite side are doped with acceptor atoms that result in a relatively high hole concentration (such layers are commonly referred to as p-type layers).
  • A common approach to preparing an LED is as follows. The layers of material are prepared in the form of a wafer. Typically, the layers are formed using an epitaxial deposition technique, such as metal-organic chemical vapor deposition (MOCVD), with the initially deposited layer being formed on a growth substrate. The layers are then exposed to various etching and metallization techniques to form contacts for electrical current injection, and the wafer is subsequently sectioned into individual LED chips. Usually, the LED chips are packaged.
  • During use, electrical energy is usually injected into an LED and then converted into electromagnetic radiation (light), some of which is extracted from the LED.
  • SUMMARY
  • The invention relates to light-emitting devices, and related components, systems and methods.
  • In some embodiments, a system includes system, a panel having an edge, the edge having a thickness. The system also includes a light emitting device disposed such that light emitted from the light emitting device impinges on the edge of the panel, the light emitting device having a surface. A ratio of a width of the surface of the light emitting device to the thickness of the edge of the panel is from about 0.5 to about 1.1.
  • Embodiments can include one or more of the following.
  • The panel can be a liquid crystal display (LCD). A length of the surface of the light emitting device can be at least about 1 mm. A length of the surface of the light emitting device can be at least about 2 mm. A length of the surface of the light emitting device can be at least about 3 mm. A length of the surface of the light emitting device can be at least about 5 mm. A length of the surface of the light emitting device can be at least about 10 mm.
  • The ratio of the width of the surface of the light emitting device to the thickness of the edge of the panel can be from about 0.75 to about 1.05. The ratio of the width of the surface of the light emitting device to the thickness of the edge of the panel can be about 0.9 to about 1.
  • The system can alsi include at least one optical component disposed between the light emitting device and the panel. The at least one optical component can be a light homogenizer. The light emitting device can be a non-lambertian light emitting device. The light emitting device can be a photonic lattice light emitting device.
  • The light emitting device can include a multi-layer stack of materials including a light generating region, and a first layer supported by the light generating region, a surface of the first layer being configured so that the light generated by the light generating region can emerge from the light emitting device via the surface of the first layer. The surface of the first layer can have a dielectric function that varies spatially according to a pattern, and the pattern has an ideal lattice constant and a detuning parameter with a value greater than zero. The surface of the first layer can have a dielectric function that varies spatially according to a nonperiodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a complex periodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a periodic pattern. The light emitting device can include a light emitting diode. The light emitting device can be a single light emitting device.
  • The light emitting device can include a plurality of light emitting devices. The plurality of light emitting devices can be disposed in a serrated arrangement along the edge of the panel. The plurality of light emitting devices can be disposed in a plurality of columns. The plurality of columns can include at least a first column and a second column. The first column can include a plurality of light emitting devices configured to emit a first color of light and the second column can include a plurality of light emitting devices configured to emit a second color of light, the first and second colors of light being different. The system can also include a third column that includes a plurality of light emitting devices configured to emit a third color of light, the first, second and third colors of light being different. The first, second, and third colors can be selected from the group consisting of red, green, and blue. The edge can be a first edge and the panel can also include a second edge, edge having a thickness. The system can also include a light emitting device disposed such that light emitted from the light emitting device impinges on the second edge of the panel.
  • The system can also include a cooling system configured so that, during use, the cooling system regulates a temperature of the light emitting diode. The emitting device can be mounted on a heat sink device.
  • In some embodiments, a system includes a panel having an edge and an array of light emitting devices disposed such that light emitted from the array of light emitting device impinges on the panel. The array of light emitting devices includes a first column of light emitting devices, the first column having a first edge and a second edge about perpendicular to the first edge and a second column of light emitting devices, the second column of light emitting devices having a first edge, a second edge, and a third edge, the first and second edges of the second column being about parallel to the first edge of the first column, the second edge of the second column being about parallel to the second edge of the first column, and the second edge of the second column being offset by at least about 0.05 mm from the second edge of the first column in a direction about perpendicular to the second edge of the first column.
  • Embodiments can include one or more of the following.
  • The system can include a third column of light emitting devices, the third column of light emitting devices having a first edge and a second edge, the first edge of the third column being about parallel to the third edge of the second column, the second edge of the third column being about parallel to the second edge of the second column, and the second edge of the third column being offset by at least about 0.05 mm from the second edge of the second column in a direction about perpendicular to the second edge of the first column. The panel can include a liquid crystal display (LCD). The first column can include a plurality of light emitting devices configured to emit a first color of light, the second column can include a plurality of light emitting devices configured to emit a second color of light. The first and second colors of light can be different The third column can include a plurality of light emitting devices configured to emit a third color of light, and the first, second and third colors of light being different. The first, second, and third colors can be selected from the group consisting of red, green, and blue.
  • The first column can have a first width, the second column can have a second width, and the third column can have a third width. A ratio a sum of the first, second, and third widths to a thickness of the edge of the panel can be from about 0.5 to about 1.1. At least one of the light emitting devices in the array of light emitting devices can include a first layer supported by a light generating region, a surface of the first layer being configured so that light generated by the light generating region can emerge from the light emitting device via a surface of the first layer. The surface of the first layer can have a dielectric function that varies spatially according to a pattern, and the pattern has an ideal lattice constant and a detuning parameter with a value greater than zero. The surface of the first layer can have a dielectric function that varies spatially according to a nonperiodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a complex periodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a periodic pattern.
  • The second column can be offset from the first column and the third column by at least about 0.1 mm. The second column can be offset from the first column and the third column by at least about 0.2 mm. The second column can be offset offset from the first column and the third column by at least about 0.3 mm. The second column can be offset offset from the first column and the third column by at least about 0.5 mm. The second column can be offset offset from the first column and the third column by at least about 1 mm.
  • The system can also include at least one optical component disposed between the light emitting device and the panel. The at least one optical component can be a light homogenizer. The light emitting device can be a non-lambertian light emitting device. The light emitting device can be a photonic lattice light emitting device. The light emitting device can be a light emitting diode. The array of light emitting diodes can include at least one light emitting diode selected from the group consisting of red light emitting diodes, blue light emitting diodes, and green light emitting diodes. The array of light emitting diodes can include a red light emitting diode, a blue light emitting diode, and a green light emitting diode. The array of light emitting devices can be disposed in a serrated arrangement along the edge of the panel. The system can also include a cooling system configured so that, during use, the cooling system regulates a temperature of the array of light emitting diodes.
  • In an additional embodiment, a system includes a panel having an edge, a light emitting device having a surface, the surface having an area defined by a perimeter of the surface, and an optical component disposed in an optical path from the light emitting device to the edge of the panel, the optical component including an aperture having an area defined by a perimeter of the aperture; wherein a ratio of the area of the surface of the light emitting device to the area of the aperture is from about 0.5 to about 1.1.
  • Embodiments can include one or more of the following.
  • The panel can include a liquid crystal display (LCD). The perimeter of the aperture can be rectangular and the light emitting device can be rectangular. The perimeter of the aperture can be circular and the light emitting device can be circular. The perimeter of the aperture can be trapezoidal and the light emitting device can be trapezoidal. The perimeter of the aperture can be triangular and the light emitting device can be triangular. The perimeter of the aperture can be square, and the light emitting device can be square. The perimeter of the aperture can be polygonal and the light emitting device can be circular. The perimeter of the aperture can be polygonal and the light emitting device can be polygonal. The perimeter of the aperture can be hexagonal and the light emitting device can be hexagonal. The aperture can be octagonal and the light emitting device can be octagonal.
  • The light emitting device can be a non-lambertian light emitting device. The light emitting device can be a photonic lattice light emitting device. The light emitting device can include a multi-layer stack of materials including a light generating region, and a first layer supported by the light generating region, a surface of the first layer being configured so that the light generated by the light generating region can emerge from the light emitting device via the surface of the first layer. The surface of the first layer can have a dielectric function that varies spatially according to a pattern, and the pattern has an ideal lattice constant and a detuning parameter with a value greater than zero. The surface of the first layer can have a dielectric function that varies spatially according to a nonperiodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a complex periodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a periodic pattern. The light emitting device can be a light emitting diode.
  • The optical component can be configured to homogenize light emitted from the LED. The optical component can be configured to disperse light from the LED along the edge of the panel. The system can also include a cooling system configured so that, during use, the cooling system regulates a temperature of the light emitting device. The light emitting device can be mounted on a heat sink device.
  • In certain embodiments, a system includes a panel having an edge, an array of light emitting devices, the array of light emitting devices having a combined surface area defined by an outer perimeter of the array of light emitting devices, and an optical component disposed in an optical path from the light emitting device to the edge of the panel, the optical component including an aperture having an area defined by a perimeter of the aperture; wherein a ratio of the combined surface area of the light emitting devices to the area of the aperture is from about 0.5 to about 1.1.
  • Embodiments can include one or more of the following.
  • The panel can be liquid crystal display (LCD). The perimeter of the aperture can be rectangular and the perimeter of the array of light emitting devices can be rectangular. The perimeter of the aperture can be hexagonal and the perimeter of the array of light emitting devices can be hexagonal. The array of light emitting devices can include six light emitting devices and each light emitting device in the array of light emitting devices can have a perimeter defining a triangular shape. The perimeter of the aperture can be octagonal and the perimeter of the array of light emitting devices can be octagonal. The array of light emitting devices can include eight light emitting devices and each light emitting device in the array of light emitting devices can have a perimeter defining a triangular shape. The perimeter of the aperture can be circular, and the perimeter of the array of light emitting devices can be circular. The array of light emitting devices can include four light emitting devices and each light emitting device in the array of light emitting devices can have a perimeter defining a shape of about ¼ of a circle. The array of light emitting devices can include two light emitting devices and each light emitting device in the array of light emitting devices can have a perimeter defining a shape of about ½ of a circle. The array of light emitting devices can include six light emitting devices and each light emitting device in the array of light emitting devices can have a perimeter defining a shape of about ⅙ of a circle. The array of light emitting devices can include eight light emitting devices and each light emitting device in the array of light emitting devices can have a perimeter defining a shape of about ⅛ of a circle. The perimeter of the aperture can be trapezoidal and perimeter of the array of light emitting devices can be trapezoidal. The perimeter of the aperture can be triangular and the perimeter of the array of light emitting devices can be triangular. The perimeter of the aperture can be square and the perimeter of the array of light emitting devices can be square.
  • At least one light emitting device can be a non-lambertian light emitting device. At least one light emitting device can be a photonic lattice light emitting device. At least one of the light emitting devices in the array of light emitting devices can include a first layer supported by a light generating region, a surface of the first layer being configured so that light generated by the light generating region can emerge from the light emitting device via a surface of the first layer. The surface of the first layer can have a dielectric function that varies spatially according to a pattern, and the pattern has an ideal lattice constant and a detuning parameter with a value greater than zero. The surface of the first layer can have a dielectric function that varies spatially according to a nonperiodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a complex periodic pattern. The surface of the first layer can have a dielectric function that varies spatially according to a periodic pattern.
  • At least one light emitting device can be a light emitting diode. The array of light emitting diodes can include at least one light emitting diode selected from the group consisting of red light emitting diodes, blue light emitting diodes, and green light emitting diodes. The array of light emitting diodes can include at least one red light emitting diode, at least one blue light emitting diode, and at least one green light emitting diode. The optical component can be configured to homogenize light emitted from the LED. The optical component can be configured to disperse light from the LEDs along the edge of the panel. The system can also include a cooling system configured so that, during use, the cooling system regulates a temperature of the light emitting diode. The array of light emitting devices can be mounted on a heat sink device
  • Features and advantages of the invention are in the description, drawings and claims.
  • DESCRIPTION OF DRAWINGS
  • FIG. 1 is a schematic representation of a light emitting system.
  • FIG. 2A-2D are schematic representations of optical display systems.
  • FIG. 3 is a schematic representation of an optical display system.
  • FIG. 4A is a schematic representation of a top view of an LED.
  • FIG. 4B is a schematic representation of an optical display system.
  • FIG. 5 is a schematic representation of an optical display system.
  • FIG. 6 is a schematic representation of an optical display system.
  • FIG. 7 is a schematic representation of an optical display system.
  • FIGS. 8A and 8B are schematic representations of an optical display system.
  • FIG. 9 is a schematic representation of an optical display system.
  • FIG. 10 is a schematic representation of an optical display system.
  • FIG. 11 is a schematic representation of an optical display system.
  • FIG. 12A is a schematic representation of an optical display system.
  • FIG. 12B is a schematic representation of an optical display system.
  • FIG. 13 is a schematic representation of an optical display system.
  • FIG. 14A is a schematic representation of an optical display system.
  • FIG. 14B is a top view of an array of LEDs.
  • FIG. 15 is a schematic representation of an optical display system.
  • FIG. 16 is a top view of an array of LEDs.
  • FIG. 17 is a top view of an array of LEDs.
  • FIG. 18 is a top view of an array of LEDs.
  • FIG. 19 is a top view of an array of LEDs.
  • FIG. 20 is a top view of an array of LEDs.
  • FIG. 21 is a schematic representation of an optical display system.
  • FIG. 22A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 22B is a cross sectional view of the array of LEDs of FIG. 22A.
  • FIG. 22C is a cross sectional view of the optical component of FIG. 22A.
  • FIG. 23A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 23B is a cross sectional view of the array of LEDs of FIG. 23A.
  • FIG. 23C is a cross sectional view of the optical component of FIG. 23A.
  • FIG. 24A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 24B is a cross sectional view of the array of LEDs of FIG. 24A.
  • FIG. 24C is a cross sectional view of the optical component of FIG. 24A.
  • FIG. 25A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 25B is a cross sectional view of the array of LEDs of FIG. 25A.
  • FIG. 25C is a cross sectional view of the optical component of FIG. 25A.
  • FIG. 26A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 26B is a cross sectional view of the array of LEDs of FIG. 26A.
  • FIG. 26C is a cross sectional view of the optical component of FIG. 26A.
  • FIG. 27A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 27B is a cross sectional view of the array of LEDs of FIG. 27A.
  • FIG. 27C is a cross sectional view of the optical component of FIG. 27A.
  • FIG. 28A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 28B is a cross sectional view of the array of LEDs of FIG. 28A.
  • FIG. 28C is a cross sectional view of the optical component of FIG. 28A.
  • FIG. 29A is a schematic representation of an optical component and an array of LEDs.
  • FIG. 29B is a cross sectional view of the array of LEDs of FIG. 29A.
  • FIG. 29C is a cross sectional view of the optical component of FIG. 29A.
  • FIG. 30 is a schematic representation of an optical display system.
  • FIG. 31 is a schematic representation of an optical display system.
  • FIG. 32 is a cross-sectional view of an LED with a patterned surface.
  • FIG. 33 is a top view the patterned surface of the LED of FIG. 12.
  • FIG. 34 is a graph of an extraction efficiency of an LED with a patterned surface as function of a detuning parameter.
  • FIG. 35 is a schematic representation of the Fourier transformation of a patterned surface of an LED.
  • FIG. 36 is a graph of an extraction efficiency of an LED with a patterned surface as function of nearest neighbor distance.
  • FIG. 37 is a graph of an extraction efficiency of an LED with a patterned surface as function of a filling factor.
  • FIG. 38 is a top view a patterned surface of an LED.
  • FIG. 39 is a graph of an extraction efficiency of LEDs with different surface patterns.
  • FIG. 40 is a graph of an extraction efficiency of LEDs with different surface patterns.
  • FIG. 41 is a graph of an extraction efficiency of LEDs with different surface patterns.
  • FIG. 42 is a graph of an extraction efficiency of LEDs with different surface patterns.
  • FIG. 43 is a schematic representation of the Fourier transformation two LEDs having different patterned surfaces compared with the radiation emission spectrum of the LEDs.
  • FIG. 44 is a graph of an extraction efficiency of LEDs having different surface patterns as a function of angle.
  • FIG. 45 is a side view of an LED with a patterned surface and a phosphor layer on the patterned surface.
  • FIG. 46 is a cross-sectional view of a multi-layer stack.
  • FIG. 47 is a cross-sectional view of a multi-layer stack.
  • FIG. 48 is a cross-sectional view of a multi-layer stack.
  • FIG. 49 is a cross-sectional view of a multi-layer stack.
  • FIG. 50 depicts a side view of a substrate removal process.
  • FIG. 51 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 52 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 53 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 54 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 55 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 56 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 57 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 58 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 59 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 60 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 61 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 62 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 63 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 64 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 65 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 66 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 67 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 68 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 69 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 70 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 71 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 72 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 73 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 74 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 75 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 76 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 77 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 78 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 79 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 80 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 81 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 82 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 83 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 84 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 85 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 86 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 87 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 88 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 89 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 90 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 91 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 92 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 93 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 94 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 95 is a perspective view of a wafer.
  • FIG. 96 is a perspective view of a wafer.
  • FIG. 97A is a perspective view of an LED.
  • FIG. 97B is a top view of an LED.
  • FIG. 98A is a top view of an LED.
  • FIG. 98B is a partial cross-sectional view of an LED.
  • FIG. 98C is an equivalent circuit diagram.
  • FIG. 99A is a top view of an LED.
  • FIG. 99B is an equivalent circuit diagram.
  • FIG. 100A is a top view of an LED.
  • FIG. 100B is an equivalent circuit diagram.
  • FIG. 101A is a top view of an LED.
  • FIG. 101B is a partial cross-sectional view of an LED.
  • FIG. 101C is a partial cross-sectional view of an LED.
  • FIG. 102 is a graph of junction current density.
  • FIG. 103A is a top view of a multi-layer stack.
  • FIG. 103B is a partial cross-sectional view of an LED.
  • FIG. 104 is a view of a contact.
  • FIG. 105 is a diagram of a packaged LED.
  • FIG. 106 is a diagram of a packaged LED and a heat sink.
  • FIG. 107 is a graph of resistance.
  • FIG. 108 is a graph of junction temperature.
  • FIG. 109 is a diagram of a packaged LED.
  • FIG. 110A is a partial cross-sectional view of an LED.
  • FIGS. 110B is a top view a patterned surface of an LED.
  • FIGS. 110C is a top view a patterned surface of an LED.
  • FIGS. 110D is a top view a patterned surface of an LED.
  • FIG. 111 is a partial cross-sectional view of an LED.
  • FIG. 112 is a partial cross-sectional view of an LED.
  • FIG. 113 is a partial cross-sectional view of an LED.
  • FIG. 114 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 115 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 116 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 117 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 118 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 119 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 120 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 121 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 122 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 123 is a partial cross-sectional view of an LED
  • FIG. 124 is a partial cross-sectional view of an LED.
  • FIG. 125 is a partial cross-sectional view of an LED.
  • FIG. 126 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 127 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 128 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 129 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 130 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 131 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 132 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 133 is a partial cross-sectional view of a multi-layer stack.
  • FIG. 134 is a partial cross-sectional view of an LED.
  • FIG. 135 is a partial cross-sectional view of an LED.
  • FIG. 136A and 136B are schematic representations of a reflective surface.
  • FIG. 137 is a graph of light emission versus wavelength.
  • FIG. 138A is a schematic representation of a reflective surface.
  • FIG. 138B is a schematic representation of a reflective surface.
  • FIG. 139A is a schematic representation of a boundary condition.
  • FIG. 139B is a graph of a cut-off frequency.
  • FIG. 140 is a graph of light emission versus wavelength.
  • FIG. 141 is a graph of light emission versus wavelength.
  • Like reference symbols in the various drawings indicate like elements.
  • DETAILED DESCRIPTION
  • FIG. 1 is a schematic representation of a light-emitting system 50 that has an array 60 of LEDs 100 incorporated therein. Array 60 is configured so that, during use, light that emerges from LEDs 100 (see discussion below) emerges from system 50 via surface 55.
  • Examples of light-emitting systems include projectors (e.g., rear projection projectors, front projection projectors), portable electronic devices (e.g., cell phones, personal digital assistants, laptop computers), computer monitors, large area signage (e.g., highway signage), vehicle interior lighting (e.g., dashboard lighting), vehicle exterior lighting (e.g., vehicle headlights, including color changeable headlights), general lighting (e.g., office overhead lighting), high brightness lighting (e.g., streetlights), camera flashes, medical devices (e.g., endoscopes), telecommunications (e.g. plastic fibers for short range data transfer), security sensing (e.g. biometrics), integrated optoelectronics (e.g., intrachip and interchip optical interconnects and optical clocking), military field communications (e.g., point to point communications), biosensing (e.g. photo-detection of organic or inorganic substances), photodynamic therapy (e.g. skin treatment), night-vision goggles, solar powered transit lighting, emergency lighting, airport runway lighting, airline lighting, surgical goggles, wearable light sources (e.g. life-vests). An example of a rear projection projector is a rear projector television. An example of a front projection projector is a projector for displaying on a surface, such as a screen or a wall. In some embodiments, a laptop computer can include a front projection projector.
  • Typically, surface 55 is formed of a material that transmits at least about 20% (e.g., at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%) of the light that emerges from LEDs 100 and impinges on surface 55. Examples of materials from which surface 55 can be formed include glass, silica, quartz, plastic, and polymers.
  • In some embodiments, it may be desirable for the light that emerges (e.g., total light intensity, light intensity as a function of wavelength, and/or peak emission wavelength) from each LED 100 to be substantially the same. An example is time-sequencing of substantially monochromatic sources (e.g. LEDs) in display applications (e.g., to achieve vibrant full-color displays). Another example is in telecommunications where it can be advantageous for an optical system to have a particular wavelength of light travel from the source to the light guide, and from the light guide to the detector. A further example is vehicle lighting where color indicates signaling. An additional example is in medical applications (e.g., photosensitive drug activation or biosensing applications, where wavelength or color response can be advantageous).
  • In certain embodiments, it may be desirable for the light that emerges (e.g., total light intensity, light intensity as a function of wavelength, and/or peak emission wavelength) from at least some of LEDs 100 to be different from the light that emerges (e.g., total light intensity, light intensity as a function of wavelength, and/or peak emission wavelength) from different LEDs 100. An example is in general lighting (e.g., where multiple wavelengths can improve the color rendering index (CRI)). CRI is a measurement of the amount of color shift that objects undergo when lighted by the light-emitting system as compared with the color of those same objects when seen under a reference lighting system (e.g., daylight) of comparable correlated temperature. Another example is in camera flashes (e.g., where substantially high CRI, such as substantially close to the CRI of noontime sunlight, is desirable for a realistic rendering of the object or subject being photographed). A further example is in medical devices (e.g., where substantially consistent CRI is advantageous for tissue, organ, fluid, etc. differentiation and/or identification). An additional example is in backlighting displays (e.g., where certain CRI white light is often more pleasing or natural to the human eye).
  • Although depicted in FIG. 1 as being in the form of an array, LEDs 100 can be configured differently. As an example, in some embodiments, system 50 includes a single LED 100. As another example, in certain embodiments, the array is curved to help angularly direct the light from various sources onto the same point (e.g., an optic such as a lens). As a further example, in some embodiments, the array of devices is hexagonally distributed to allow for close-packing and high effective surface brightness. As an additional example, in certain embodiments, the devices are distributed around a mirror (e.g., a dichroic mirror) that combines or reflects light from the LEDs in the array.
  • In FIG. 1 the light that emerges from LEDs 100 is shown as traveling directly from LEDs 100 to surface 55. However, in some embodiments, the light that emerges from LEDs 100 can travel an indirect path from LEDs 100 to surface 55. As an example, in some embodiments, system 50 includes a single LED 100. As another example, in certain embodiments, light from LEDs 100 is focused onto a microdisplay (e.g., onto a light valve such as a digital light processor (DLP) or a liquid crystal display (LCD)). As a further example, in some embodiments, light is directed through various optics, mirrors or polarizers (e.g., for an LCD). As an additional example, in certain embodiments, light is projected through primary or secondary optics, such as, for example, a lens or a set of lenses.
  • FIG. 2A shows an optical display system 1100 (see discussion above) including a non-Lambertian LED 1110 (see discussion below), a lens 1120 and a microdisplay 1130. LED 1110 is spaced a distance L1 from lens 1120, and microdisplay 1130 is spaced a distance L2 from lens 1120. Distances L1 and L2 are selected so that, for light emitted by LED 1110 that impinges on lens 1120, the image plane of lens 1120 coincides with the surface of microdisplay 1130 on which the light emitted by LED 1110 impinges.
  • With this arrangement, system 1100 can use the light emitted by LED 1110 to relatively efficiently illuminate the surface of microdisplay 1130 with the shape of the surface of LED 1110 that emits light being about the same as the shape of the surface of 1130 that is illuminated by the light emitted by LED 1110. For example, in some embodiments, the ratio the aspect ratio of LED 1110 to the aspect ratio of microdisplay 1130 can be from about 0.5 to about 2 (e.g., from about 9/16 to about 16/9, from about 3/4 to about 4/3, about 1). The aspect ratio of microdisplay 1130 can be, for example, 1920×1080, 640×480, 800×600, 1024×700, 1024×768, 1024×720, 1280×720, 1280×768, 1280×960, or 1280×1064.
  • In general, the surface of microdisplay 1130 and/or the surface of LED 1110 can have any desired shape. Examples of such shapes include square, circular, rectangular, triangular, trapezoidal, and hexagonal.
  • In some embodiments, an optical display system can relatively efficiently illuminate the surface of microdisplay 1130 without a lens between LED 1110 and microdisplay 1130 while still having the shape of the surface of LED 1110 that emits light being about the same as the shape of the surface of 1130 that is illuminated by the light emitted by LED 1110. For example, FIG. 2B shows a system 1102 in which a square LED 1110 is imaged onto a square microdisplay 1130 without having a lens between LED 1110 and microdisplay 1130. As another example, FIG. 2C shows an optical display system 1104 in which a rectangular LED 1110 can be imaged onto a rectangular microdisplay 1130 (with a similarly proportioned aspect ratio) without having a lens between LED 1110 and microdisplay 1130.
  • In certain embodiments, an anamorphic lens can be disposed between LED 1110 and microdisplay 1130. This can be desirable, for example, when the aspect ratio of LED 1110 is substantially different from the aspect ratio of microdisplay 1130. As an example, FIG. 2D shows a system 1106 that includes LED 1110 having a substantially square shaped surface, microdisplay 1130 having a substantially rectangular shaped surface (e.g., an aspect ratio of about 16:9 or about 4:3), and an anamorphic lens 1120 disposed between LED 1110 and microdisplay 1130. In this example, anamorphic lens 1120 can be used to convert the shape of the light emitted by LED 1110 to substantially match the shape of the surface of microdisplay 1130. This can enhance the efficiency of the system by increasing the amount of light emitted by the surface of LED 1110 that impinges upon the surface of microdisplay 1130.
  • FIG. 3 shows an optical display system 1200 including LED 1110, lens 1120, and microdisplay 1130. The light emitting surface of LED 1110 has contact regions to which electrical leads 1115 are attached (see discussion below). LED 1110 is spaced a distance L3 from lens 1120, and microdisplay 1130 is spaced a distance L4 from lens 1120. Leads 1115 block light from being emitted from the contact regions of LED 1110. If the plane of the surface of microdisplay 1130 on which the light emitted by LED 1110 impinges coincides with the image plane of lens 1120, a set of dark spots 1202 corresponding to the contact region of the light emitting surface of LED 1110 can appear on this surface of microdisplay 1130. To reduce the area of this surface of microdisplay 1130 that is covered by the dark spots, distances L3 and L4 are selected so that, for light emitted by LED 1110 that impinges on lens 1120, the image plane of lens 1120 does not coincide with the plane of the surface of microdisplay 1130 on which the light emitted by LED 1110 impinges (i.e., there exists a distance, ΔL, between the image plane of lens 1120 and the plane of the surface of microdisplay 1130 on which the light emitted by LED 1110 impinges). With this arrangement, the light from LED 1110 is defocused in the plane of the surface of microdisplay 1130 on which the light emitted by LED 1110 impinges, and the resulting intensity of light is more uniform on this surface of microdisplay 1130 than in the image plane of lens 1120. The total distance between the LED and the microdisplay 1130 can be represented as the distance between the LED 1110 and the image plane 1120 (L5) plus the distance, ΔL. In general, as ΔL is increased by increasing the distance between the LED 1110 and the microdisplay 1130, the intensity of dark spots decreases but the intensity of light emitted by LED 1110 that impinges on the surface of microdisplay 1130 decreases. Alternately, when the microdisplay is translated such that the distance between the LED 1110 and the microdisplay 1130 is decreased, the intensity is greater than the intensity at the image plane, but the microdisplay may be only partially illuminated. In some embodiments, the absolute value of ΔL/L5 is from about 0.00001 to about 1 (e.g., from about 0.00001 to about 0.1, from about 0.00001 to about 0.01, from about 0.00001 to about 0.001), or from about 0.00001 to about 0.0001). In some embodiments, multiple LEDs may be used to illuminate a single microdisplay (e.g., a 3×3 matrix of LEDs). Such a system can be desirable because, when multiple LEDs are arranged to illuminate a single microdisplay, if one LEDs fails, the system would still be useable (however a dark spot may occur due to the absence of light from the particular LED). If multiple LEDs are used to illuminate a single microdisplay, the optical system can be configures so that dark spots do not appear on the surface of the microdisplay. For example, the microdisplay can be translated outside of the image plane such that the area between the LEDs does not result in a dark spot.
  • In some embodiments, the intensity of dark spots on the surface of microdisplay 1130 can be reduced by appropriately configuring the contact region of the surface of LED 1110. For example, FIG. 4A shows a top view of an LED 1110 with a contact region disposed around the perimeter of LED 1110. With this arrangement, with or without the presence of a lens (with or without defocusing), the optical display system can be configured (e.g., by properly sizing the area of the surface of microdisplay 1130) so that the intensity of the dark spots created by the contact region of the surface of LED 1110 on surface 1130 is relatively small. This approach may be used with systems that include multiple LEDs (e.g., a 3×3 matrix of LEDs).
  • As another example, FIG. 4B shows an optical display system 300 that includes LED 1110 and microdisplay 1130. LED 1110 includes a contact region formed by leads 1115 that is selected so that dark spots 1202 appear at a region not imaged on the surface of microdisplay 1130. In this example, the surface of microdisplay 1130 can be located at the image plane of lens 1120 because the dark spots fall outside of the area imaged on the microdisplay at the image plane of lens 1120. If the shape of LED 1110 is matched to the shape of microdisplay 1130, leads 1115 can be disposed, for example, on the surface of LED 1110 around its perimeter. In this example, the area inside the contact region of surface 1110 matches (e.g., the aspect ratio is similar) to the surface of microdisplay 1130. This approach may be used with systems that include multiple LEDs (e.g., a 3×3 matrix of LEDs).
  • As a further example, FIG. 5 shows an optical display system 1700 that includes LED 1110 and microdisplay 1130. LED 1110 also includes a contact region formed by leads 1115 and a homogenizer 1702 (also referred to as a light tunnel or light pipe) that guides light emitted from LED 1110 to a lens 1120. Total internal reflection of the light emitted by LED 1110 off the inside surfaces of homogenizer 1702 can generate a substantially uniform output distribution of light and can reduce the appearance of dark spots caused by leads 1115 so that microdisplay 1130 is substantially uniformly illuminated by LED 1110 (e.g., an image generated in an image plane 1131 is substantially uniform).
  • Optionally, system 1700 can include one or more additional optical components. For example, in some embodiments, optical display system 1700 can also include a lens disposed in the path prior to the homogenizer to focus light into the homogenizer. In certain embodiments, the aspect ratio of the aperture of homogenizer 1702 matches that of LED 1110 such that when LED 1110 is mounted in close proximity to homogenizer 1702, additional lenses may not be necessary or such that more efficient coupling of light into homogenizer 1702 is possible with a lens prior to homogenizer 1702.
  • As an additional example, FIG. 6 shows an optical display system 1710 that includes LED 1110 and microdisplay 1130. LED 1110 also includes a contact region formed by leads 1115 and a set of multiple lenses 1712 that are disposed between LED 1110 and lens 1120. Lenses 1712 can vary in size, shape, and number. For example, the number and size of lenses 1712 can be proportional to the cross-sectional area of LED 1110. In some embodiments, lenses 1712 include a set of between about 1 and about 100 lenses with sizes varying of, for example, from about 1 mm to about 10 cm. The light emitted by LED 1110, enters lenses 1712 and is refracted. Since the surfaces of lenses 1712 are curved, the light refracts at different angles causing the beams emerging from lenses 1712 to overlap. The overlapping of the beams reduces the appearance of dark spots caused by leads 1115 so that microdisplay 1130 is substantially uniformly illuminated by LED 1110 (e.g., an image generated in an image plane 1131 is substantially uniform).
  • While optical display systems have been described as including a single lens, in some embodiments, multiple lenses can be used. Further, in certain embodiments, one or more optical components other than lens(es) can be used. Examples of such optical components include mirrors, reflectors, collimators, beam splitters, beam combiners, dichroic mirrors, filters, polarizers, polarizing beam splitters, prisms, total internal reflection prisms, optical fibers, light guides and beam homogenizers. The selection of appropriate optical components, as well as the corresponding arrangement of the components in the system, is known to those skilled in the art.
  • Moreover, although optical display systems have been described as including one non-Lambertian LED, in some embodiments, more than one non-Lambertian LED can be used to illuminate microdisplay 1130. For example, FIG. 7 shows a system 1500 that includes a blue LED 1410 (an LED with a dominant output wavelength from about 450 to about 480 nm), a green LED 1420 (an LED with a dominant output wavelength from about 500 to about 550 nm), and a red LED 1430 (an LED with a dominant output wavelength from about 610 to about 650 nm) which are in optical communication with the surface of microdisplay 1130. LEDS 1410, 1420, and 1430 can be arranged to be activated simultaneously, in sequence or both. In other embodiments, at least some of the LEDs may be in optical communication with separate microdisplay surfaces.
  • In some embodiments, LEDs 1410, 1420, and 1430 are activated in sequence. In such embodiments, a viewer's eye generally retains and combines the images produced by the multiple colors of LEDs. For example, if a particular pixel (or set of pixels) or microdisplay (or portion of a microdisplay) of a frame is intended to be purple in color, the surface of the microdisplay can be illuminated with red LED 1430 and blue LED 1410 during the appropriate portions of a refresh cycle. The eye of a viewer combines the red and the blue and “sees” a purple microdisplay. In order for a human not to notice the sequential illumination of the LEDs, a refresh cycle having an appropriate frequency (e.g., a refresh rate greater than 120 Hz) can be used.
  • LEDs 1410, 1420 and 1430 may have varying intensities and brightness. For example, green LED 1420 may have a lower efficiency than red LED 1430 or blue LED 1410. Due to a particular LED (e.g., green LED 1420) having a lower efficiency, it can be difficult to illuminate the surface of the microdisplay with a sufficiently high brightness of the color of light (e.g., green) emitted by the relatively low efficiency LED (e.g., LED 1420). To compensate for this disparity in efficiency (to produce an image that is not distorted due to the difference in light brightness), the activation cycles for the multiple LEDs can be adjusted. For example, the least efficient LED may be allocated a longer activation time (i.e., on for a longer period of time) than the more efficient LEDs. In a particular example, for a red/green/blue projection system instead of a 1/3:1/3:1/3 duty cycle allocation, the cycle may be in the ratio of 1/6:2/3:1/6 (red:green:blue). In another example, the cycle may be in the ratio of 0.25:0.45:0.30 (red:green:blue). In other examples, the duty cycle dedicated to the activation of the green LED may be further increased. For example, the duty cycle dedicated to imaging the green LED 1420 can be greater than about 40% (e.g., greater than about 45%, greater than about 50%, greater than about 60%, greater than about 70%, greater than about 80%, greater than about 90%). In some embodiments, the duty cycle for each LED is different. As an example, the duty cycle for red LED 1430 can be greater than the duty cycle for blue LED 1410. While systems have been described in which the activation cycle is selected based on the intensity and/or brightness of an LED, in some systems the activation time of an LED may be selected based on one or more other parameters. In some examples, the activation time of the least efficient light emitting device is at least about 1.25 times (e.g., at least about 1.5 times, at least about 2 times, at least about 3 times) the activation time of another light emitting device.
  • FIG. 8A shows an embodiment of a liquid crystal display (LCD) based optical display system 1720 including blue LED 1410, green LED 1420, and red LED 1430 (e.g., as described above) which are in optical communication with the surface of associated LCD panels 1728, 1730, and 1732. Optical display system 1720 also includes lenses 1722, 1724, and 1726 in a corresponding optical path between LEDs 1410, 1420, and 1430 and associated LCD panels 1728, 1730, and 1732. Lenses 1722, 1724, and 1726 focus the light onto associated LCD panels 1728, 1730, and 1732. Optical display system 1720 further includes a device 1734 (e.g., an x-cube) that combines multiple beams of light from LCD panels 1728, 1730, and 1732 into a single beam 1736 (indicated by arrows) that can be directed to a projection lens 1735 or other display Optionally, optical display system 1720 can include a polarizer that transmits a desired polarization (e.g. the ‘p’ polarization) while reflecting another polarization (e.g. the ‘s’ polarization). The polarizer can be disposed in the path between LEDs 1410, 1420, and 1430 and associated lenses 1722, 1724, and 1726, between lenses 1722, 1724, and 1726 and the associated LCD panels 1728, 1730, and 1732, or in other locations along the optical path. As shown in FIG. 8B, in some embodiments the aspect ratio of an LED (e.g., LED 1430) can be matched to the aspect ratio of the microdisplay (e.g., microdisplay 1732) as described above.
  • FIG. 9 shows an embodiment of a digital light processor (DLP) based optical display system 1750 including blue LED 1410, green LED 1420, and red LED 1430 (as described above) which are each in optical communication with associated lenses 1722, 1724, and 1726 (as described above). Light emitted from LEDs 1410, 1420, and 1430 passes through the associated lenses 1722, 1724, and 1726 and is collected by a device 1734 (e.g., an x-cube) that combines multiple beams of light emitted by LEDs 1410, 1420, and 1430 into a single beam that can be directed to a total internal reflection (TIR) prism 1752. For example, the light emerging from x-cube 1734 can be directed to TIR prism 1752 by a mirror 1754 or other device such as a light guide. TIR prism 1752 reflects light and directs the light to a DLP panel 1756. DLP panel 1756 includes a plurality of mirrors that can be actuated to generate a particular image. For example, a particular mirror can either reflect light 1760 (indicated by arrows) such that the light is directed to a projection 1755 or can cause the light to be reflected away from projection lens 1755. The combination of the LEDs 1410, 1420, and 1430 and DLP panel 1756 allow greater control of the signal. For example, the amount of data sent to DLP panel 1756 can be reduced (allowing greater switching frequency) by switching on and off LEDs 1410, 1420, and 1430 in addition to the mirrors in DLP panel 1756. For example, if no red is needed in a particular image, red LED 1430 can be switched off eliminating the need to send a signal to DLP 1752 to switch the associated mirror. The ability to modulate the LEDs can improve for example color quality, image quality, or contrast.
  • FIG. 10 shows a particular embodiment of a liquid crystal on silicon (LCOS) based optical display system 1770 including blue LED 1410, green LED 1420, and red LED 1430 (as described above) which are each in optical communication with an associated polarizing beam splitter 1774, 1778, and 1782. Light emitted from LEDs 1410, 1420, and 1430 passes through the associated polarizing beam splitters 1774, 1778, and 1782 and is projected onto an associated LCOS panel 1772, 1776, or 1780. Since LCOS panels 1772, 1776, and 1780 are not sensitive to all polarizations of light, the polarizing beam splitters 1774, 1778, and 1782 polarize the light to a particular polarization (e.g., by transmitting a desired polarization (e.g., the ‘p’ polarization) while reflecting another polarization (e.g., the ‘s’ polarization) the polarization of some light and pass other polarizations) based on the sensitivity of LCOS panels 1772, 1776, and 1780. The light reflected from LCOS panels 1772, 1776, and 1780 is collected by a device 1734 (e.g., an x-cube) that combines the beams of light from the multiple LCOS panels 1772, 1776, and 1780 to generate a beam 1790 (indicated by arrows) that is directed to a projection lens 1795.
  • While in the above examples, the optical display system includes red, green, and blue light emitting devices, other colors and combinations are possible. For example, the system need not have only three colors. Additional colors such as yellow may be included and allocated a portion of the duty cycle. Alternately, multiple LEDs having different dominant wavelengths may be optically combined to produce a resulting color. For example, a blue-green LED (e.g., an LED with a dominant wavelength between the wavelength of blue and green) can be combined with a yellow LED to produce ‘green’ light. In general, the number of LEDs and the color of each LED can be selected as desired. Additional microdisplays can also be included.
  • In some embodiments, the duty cycle for the lesser efficient LED (e.g. green) can be increased by various data compression techniques and algorithms. For example, sending only the difference in image information from the previous image rather than the total information required to reconstruct each image allows an increase in the data rate. Using this method, less data needs to be sent allowing for higher data rates and reduced duty cycles for complementary colors for a given refresh cycle.
  • In embodiments in which multiple LEDs are used to illuminate a given microdisplay, optical componentry may or may not be present along the light path between one or more of the LEDs and the microdisplay. For example, an x-cube or a set of dichroic mirrors may be used to combine light from the multiple LEDs onto a single microdisplay. In embodiments in which optical componentry is present along the light path, different optical componentry can be used for each LED (e.g. if the surface of the LEDs are of different size or shape), or the same optical componentry can be used for more than one LED.
  • In some embodiments, differing brightness for a particular color based on the desired chromaticity of an image may be obtained by illuminating the display for a portion of the activation time allocated to the particular LED. For example, to obtain an intense blue, the blue LED can be activated for the entire activation time and for a less intense blue, the blue LED is activated for only a portion of the total allocated activation time. The portion of the activation time used to illuminate the display can be modulated, for example, by a set of mirrors that can be positioned to either pass light to the microdisplay or reflect the light away from the microdisplay.
  • In certain embodiments, an array of moveable microdisplays (e.g., a moveable mirror) is actuated to produce a desired intensity. For example, each micromirror can represent a pixel and the intensity of the pixel can be determined by the positioning of the microdisplay. For example, the micromirror can be in an on or an off state and the proportion of the time spent in the on state during the activation time of a particular color of LED determines the intensity of the image.
  • In general, in embodiments in which multiple LEDs are used, one or more of the LEDs (e.g., each LED) can have the aspect ratio relationship described above with respect to the aspect ratio of microdisplay 1130.
  • FIG. 11 shows an optical display system 1600 that includes LED 1110, microdisplay 1130, a cooling system 1510, and a sensor 1520 that is in thermal communication with LED 1110 and electrical communication with cooling system 1510 so that, during use of system 1600, sensor 1520 and cooling system 1510 can be used to regulate the temperature of LED 1110. This can be desirable, for example, when LED 1110 is a relatively large are LED (see discussion below) because such an LED can generate a significant amount of heat. With the arrangement shown in FIG. 11, the amount of power input to LED 1110 can be increased with (primarily, increased operational efficiency at higher drive currents) reduced risk of damaging LED 1110 via the use of sensor 1520 and cooling system 1510 to cool LED 1110. Examples of cooling systems include thermal electric coolers, fans, heat pipes, and liquid cooling systems. Sensor 1520 can be, for example, manually controlled or computer controlled. In some embodiments, the system may not include a sensor (e.g., cooling system 1510 can be permanently on, or can be manually controlled). The use of a cooling system can provide multiple advantages such as reducing the likelihood of damage to the LED resulting from an excess temperature and increasing the efficiency of the LED at higher drive currents. The cooling system may also reduce the shift in wavelength induced by temperature.
  • In some embodiments, using a non-lambertian LED results in non-uniform angular distribution of light. In such embodiments, the microdisplay can be translated away from the image plane to reduce the appearance of the angular non-uniformity. In certain embodiments, information flow to the microdisplay can be achieved using an electrical or optical connection. In some examples, the rate of information flow can be increased using an optical connection.
  • In some embodiments, the size of a PLLED or other non-lambertian source can be increased and the light can be collected at a smaller angle. This can increase the brightness of the image on a display.
  • FIGS. 12A and 12B show an optical display system 2200 that includes multiple LEDs 2202, a light homogenizer 2208, and a liquid crystal display (LCD) panel 2212. LEDs 2202 are disposed along an edge 2211 of LCD panel 2212 and emit light (represented by arrows 2206) to illuminate LCD panel 2212, allowing LCD panel 2212 to display an image. The light 2206 emitted by LEDs 2202 impinges on light homogenizer 2208 (e.g., a light tunnel, a light pipe) that guides light 2206 to LCD panel 2212 (represented by arrows 2210). Total internal reflection of light 2206 off the inside surfaces of homogenizer 2208 generates a substantially uniform output distribution of light 2210 so that LCD panel 2212 is substantially uniformly illuminated by LEDs 2202 (e.g., a distribution of light entering edge 2211 of LCD panel 2212 is substantially uniform). For example, in some embodiments, a substantially uniform light distribution includes a light distribution having an intensity and/or color distribution of light entering edge 2211 that varies by at most about 20% (e.g., at most about 10%, at most about 5%, at most about 1%) at different locations on edge 2211. Subsequent to entering edge 2211 of LCD panel 2212, light 2210 reflects off internal surfaces and/or scattering centers in the LCD panel 2212 (represented by arrows 2215) and emerges from a front surface 2213 of LCD panel 2212 (represented by arrows 2217).
  • LEDs 2202 can include multiple devices that emit different wavelengths of light (e.g., red, green, blue, cyan, yellow, magenta) or that emit monochromatic light (e.g., substantially white). While in optical display system 2200 shown in FIGS. 12A and 12B, light 2206 emitted from LEDs 2202 passes through homogenizer 2208, as shown in FIG. 13, in some embodiments light emitted from LEDs 2202 (represented by arrows 2214) impinges on edge 2211 of LCD panel 2212 without passing through additional optical components. It is believed that, in some embodiments, a substantially uniform light distribution can be formed by mixing of the different wavelengths or colors of light emitted by LEDs 2202 within LCD panel 2212 as the light bounces off reflective surfaces, or scattering centers in the LCD panel 2212 (e.g., as shown in FIG. 12B).
  • FIG. 14A shows an optical display system 2229 that includes multiple LEDs 2216 a, 2216 b, 2216 c, and 2216 d that provide illumination to LCD panel 2212. FIG. 14B shows a top view of a surface 2222 of LEDs 2216 a, 2216 b, 2216 c, and 2216 d through which light emerges. The shape and placement of LEDs 2216 a, 2216 b, 2216 c, and 2216 d along edge 2211 of panel 2212 can vary as desired. FIGS. 14A and 14B show an exemplary arrangement in which multiple rectangular die are arranged along edge 2211 of panel 2212. LEDs 2216 a, 2216 b, 2216 c, and 2216 d can be mounted at a distance 2230 from edge 2211. As an example, distance 2230 can be relatively small (e.g., about one millimeter or less, about two millimeters or less, about three millimeters or less, about five millimeters or less, or about 10 millimeters). Optionally, as shown in FIG. 15, LEDs 2216 a, 2216 b, 2216 c, and 2216 d can be attached and/or embedded directly on LCD panel 2212.
  • Optical display system 2229 can include LEDs that emit light of various colors. For example, optical display system 2229 can include blue LEDs (an LED with a dominant output wavelength from about 450 to about 480 nm), green LEDs (an LED with a dominant output wavelength from about 500 to about 550 nm), and red LEDs (an LED with a dominant output wavelength from about 610 to about 650 nm) which are in optical communication with edge 2211 of LCD panel 2212. Other colors and combinations are possible. For example, the system need not have all three colors or only three colors. Additional colors such as yellow (an LED with a dominant output wavelength from about 570 to about 600 nm) and/or cyan (an LED with a dominant output wavelength from about 480 to about 500 nm), may be included. In a 5 color LED system (red, green, blue, yellow, cyan), a dominate output wavelength for blue from about 430 to 480 may be desired.
  • As described above, various colors of LEDs may have varying intensities and/or brightness. For example, a green LED may have a lower efficiency than a red or a blue LED. Due to a particular LED having a lower efficiency, in some embodiments, it may be beneficial to increase the number or size of LEDs of a particular color to compensate for this disparity in efficiency. For example, the least efficient LED may be allocated a greater percentage of the emitting area (e.g., have a larger total surface area) than the more efficient LEDs. As an example, in optical display system 2229, LEDs 2216 a, 2216 b, 2216 c, and 2216 d may include one red LED, one blue LED, and two green LEDs. The number and combination of colors can vary as desired.
  • In some embodi