Lumileds Lighting U.s., LLC

Philips Lumileds Lighting Company LLC

Hewlett-packard Company

Lumileds LLC

Christopher Haydn Lowery

Gerd O Mueller

Regina B Mueller-Mach

Troy A Trottier

Michael Ragan Krames

Michael David Camras

Frank Michael Steranka

John Julian Uebbing

Robert C Taber

Wayne L Snyder

Douglas W Pocius

Gloria E Hofler

David K McElfresh

Douglas B Adolf

Steve Burchet

Regina Mueller

James Martin

Light emitting devices with improved light extraction efficiency are provided. The light emitting devices have a stack of layers including semiconductor layers comprising an active region. The stack is bonded to a transparent optical element.

Light emitting devices with optical elements and bonding layers

Light emitting devices with improved light extraction efficiency are provided. The light emitting devices have a stack of layers including semiconductor layers comprising an active region. The stack is bonded to a transparent lens having a refractive index for light emitted by the active region preferably greater than about 1.5, more preferably greater than about 1.8. A method of bonding a transparent lens to a light emitting device having a stack of layers including semiconductor layers comprising an active region includes elevating a temperature of the lens and the stack and applying a pressure to press the lens and the stack together. Bonding a high refractive index lens to a light emitting device improves the light extraction efficiency of the light emitting device by reducing loss due to total internal reflection. Advantageously, this improvement can be achieved without the use of an encapsulant.

Light emitting devices with improved light extraction efficiency

A device includes a light emitting structure and a wavelength conversion member comprising a semiconductor. The light emitting structure is bonded to the wavelength conversion member. In some embodiments, the light emitting structure is bonded to the wavelength conversion member with an inorganic bonding material. In some embodiments, the light emitting structure is bonded to the wavelength conversion member with a bonding material having an index of refraction greater than 1.5.

A method of bonding a transparent optical element to a light emitting device having a stack of layers including semiconductor layers comprising an active region is provided. The method includes elevating a temperature of the optical element and the stack and applying a pressure to press the optical element and the stack together. In one embodiment, the method also includes disposing a layer of a transparent bonding material between the stack and the optical element. The bonding method can be applied to a premade optical element or to a block of optical element material which is later formed or shaped into an optical element such as a lens or an optical concentrator.

Method of forming light emitting devices with improved light extraction efficiency

Light emitting devices with improved light extraction efficiency are provided. The light emitting devices have a stack of layers including semiconductor layers comprising an active region. The stack is bonded to a transparent optical element having a refractive index for light emitted by the active region preferably greater than about 1.5, more preferably greater than about 1.8. A method of bonding a transparent optical element (e.g., a lens or an optical concentrator) to a light emitting device comprising an active region includes elevating a temperature of the optical element and the stack and applying a pressure to press the optical element and the light emitting device together. A block of optical element material may be bonded to the light emitting device and then shaped into an optical element. Bonding a high refractive index optical element to a light emitting device improves the light extraction efficiency of the light emitting device by reducing loss due to total internal reflection. Advantageously, this improvement can be achieved without the use of an encapsulant.

Light emitting diodes with improved light extraction efficiency

A method for forming a luminescent layer on a light emitting semiconductor device includes positioning a stencil on a substrate such that a light emitting semiconductor device disposed on the substrate is located within an opening in the stencil, depositing a stenciling composition including luminescent material in the opening, removing the stencil from the substrate, and curing the stenciling composition to a solid state. The resulting light emitting device includes a stack of layers including semiconductor layers comprising an active region and a luminescent material containing layer having a substantially uniform thickness disposed around at least a portion of the stack. A surface of the luminescent material containing layer not adjacent to the stack substantially conforms to a shape of the stack. In one embodiment, the light emitting device emits white light in a uniformly white spatial profile.

Stenciling phosphor layers on light emitting diodes

A light emitting device and a method of making the same are provided. The light emitting device includes a light emitting diode and a submount. A phosphormaterial is disposed around at least a portion of the light emitting diode. An underfill is disposed between a first surface of the light emitting diode and a first surface of the submount. The underfill reduces contamination of the light emitting diode by the phosphor material.

Reduction of contamination of light emitting devices

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

Tri-color, white light LED lamps

An LED package and a method of fabricating the LED package utilize a prefabricated fluorescent member that contains a fluorescent material that can be separately tested for optical properties before assembly to ensure the proper performance of the LED package with respect to the color of the output light. The LED package includes one or more LED dies that operate as the light source of the package. Preferably, the fluorescent material included in the prefabricated fluorescent member and the LED dies of the LED package are selectively chosen, so that output light generated by the LED package duplicates natural white light. In a first embodiment of the invention, the prefabricated fluorescent member is a substantially planar plate having a disk-like shape. In a second embodiment, the prefabricated fluorescent member is a non-planar disk that conforms to and is attached to the inner surface of a concave lens. In this embodiment, the optical properties of the fluorescent member are tested by examining an integrated unit formed by the concave lens and the attached fluorescent member. In both embodiments, the LED package includes a layer of encapsulant material that is deposited between the LED dies and the fluorescent member. In a preferred embodiment, the encapsulant material is an optical grade silicone gel, which has a high thermal stability and a desired refractive index for an efficient light extraction.

Non-incandescent lightbulb package using light emitting diodes

A light emitting device and a method of fabricating the device utilize a supplementary fluorescent material that radiates secondary light in the red spectral region of the visible light spectrum to increase the red color component of the composite output light. The secondary light from the supplementary fluorescent material allows the device to produce &ldquo;white&rdquo; output light that is well-balanced with respect to color for true color rendering applications. The supplementary fluorescent material is included in a fluorescent layer that is positioned between a die and a lens of the device. The die is preferably a GaN based die that emits light having a peak wavelength of 470 nm. The fluorescent layer also includes a main fluorescent material. Preferably, the main fluorescent material is Cerium (Ce) activated and Gadolinium (Gd) doped Yttrium Aluminum Garnet (YAG) phosphor (&ldquo;Ce:YAG phosphor&rdquo;). In a first preferred embodiment, the supplementary fluorescent material is a compound that is produced by doping the Ce:YAG phosphor with a trivalent ion of Praseodymium (Pr). In a second preferred embodiment, the supplementary fluorescent material is Europium (Eu) activated Strontium Sulphide (SrS) phosphor. The amount of supplementary phosphor in the fluorescent layer can vary depending on the amount of red color that may be required in the white output light. The exact amount of supplementary phosphor is not critical to the invention.

Red-deficiency-compensating phosphor LED

A semiconductor device has a light-emitting diode covered by a transparent spacer which separates the LED from a uniformly thick fluorescent material containing layer such that there is a more uniform lighting of the fluorescent material containing layer to provide a uniform white light.

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Fremont, CA, United States of America

Christopher Haydn Lowery