RSS

Category Archives: light emitting diode

Aurora Lighting sued by Philips for patent infringement

On November 2, 2012, Koninklijke Philips Electronics N.V. and Philips Solid-State Lighting Solutions, Inc. filed suit in the U.S. District Court for the District of Massachusetts, accusing Aurora Lighting Inc. of patent infringement of seven U.S. patents for light-emitting diode lighting technology. 

         

The accused Aurora devices include various LED retrofit bulbs designed to be installed in conventional light sockets, as well as downlight flat panel products and wallwasher products.  The asserted patents disclose various power supply configurations (see here, here, and here), multicolor bulbs (see here and here), and luminaire configurations (see here and here). 

Some of the asserted patents were among the dozens of U.S. patents obtained by Philips through its acquisition of Color Kinetics, Inc. in 2007 for a purchase price of about $791 million.  Color Kinetics was then renamed to become Philips Solid-State Lighting Solutions, Inc. 

 

Tags: , , ,

Using LEDs to illuminate a microdisplay; Luminus Devices, Inc.; U.S. Pat. No. 7,934,841

U.S. Patent No. 7,934,841, issued on May 3, 2011 to Luminus Devices, Inc. of Billerica, MA, discloses a method of illuminating a microdisplay using multiple LEDs.

   

According to the ’841 patent, microdisplays, such as digital light processors (DLPs) or liquid crystal displays (LCDs), used in various types of projectors (e.g., rear projection TVs, portable projectors) can be illuminated with multiple high-intensity LEDs.  To enhance light extraction from the LED, the surface of the LED can be patterned to spatially vary its dielectric function.  The ’841 patent discloses that a non-periodic pattern (e.g., aperiodic pattern, quasicrystalline pattern, Robinson pattern, or Ammann pattern) can be used to good effect.

According to its website, Luminus uses its “Big Chip LED” technology to produce high-performance LEDs for various applications, including lamp-free projectors with lifetimes in excess of 60,000 hours.  The company is purportedly considering going public sometime in 2012.  According to the USPTO database, Luminus has received two U.S. patents in 2011 (including the ’841 patent), and received 12 U.S. patents in 2010.  Luminus has received a total of 52 U.S. patents, 12 of which are U.S. design patents.

 

Tags: , ,

Uniform illumination from small light sources; RPC Photonics, Inc.; U.S. Pat. No. 7,918,583

U.S. Patent No. 7,918,583, issued on April 5, 2011 to RPC Photonics, Inc. of Rochester, NY, discloses an illumination device for producing uniform illumination from small light sources such as LEDs.

   

As described by the ’583 patent, various systems used to collect and collimate light from small sources, such as LEDs, suffer from non-uniform light distributions.  For example, for paraboloid reflector systems (such as are often found in flashlights), “true collimation of all the light … cannot be achieved, [since] such designs compromise between the divergence of the light and the uniformity of the resulting beam.”  Catadioptric designs can provide highly collimated beams, but when used with a smal source and a diffuser for general illumination applications, the light pattern can have one or more undesirable bright spots.  The ’583 patent discloses a lighting device or “luminaire” with a LED source, a collimator, and a diffuser that provides an angularly dependent output light intensity so as to generate a predetermined illumination pattern. 

According to its website, RPC Photonics started as a spin-off from the University of Rochester’s Institute of Optics in 1989, was acquired by Corning, Inc. in 1999, and spun-out from Corning in 2003.  The company “focuses on design, prototyping and manufacturing of optical components with precision structureed surfaces that can be applied to control light and distribute it in a highly efficient manner.” According to the USPTO database, RPC Photonics owns three U.S. patents, including the ’583 patent.

The company’s website includes a presentation titled “LED Luminaire with Controlled Light Distribution,” which appears to disclose the invention of the ’583 patent.  This presentation was given at the 2006 SPIE Optics and Photonics Conference in San Diego, CA on August 17, 2006.  Not coincidently, the filing date of the patent application that resulted in the ’583 patent was one day earlier, August 16, 2006. 

In most countries, patent protection is not available if the patent application is filed after the invention is first disclosed to the public.  The act of publicly disclosing the invention without a patent application already on file is considered in such countries to be an act of surrender of any patent rights.  By virtue of international treaties, the filing of the U.S. patent application satisfies this condition in most foreign countries.  Therefore, if RPC Photonics wanted to pursue foriegn patent protection for the “LED luminaire” invention, it had to make sure that its patent application was filed prior to its SPIE presentation, which it did. 

U.S. patent laws are less draconian.  The U.S. gives inventors a one-year grace period to get their patent application filed after the first public use or offer for sale in the U.S., or after the first printed publication description anywhere in the world.  Thus, a company only interested in pursuing U.S. patent protection has one year to disclose or offer to sell the invention to potential customers in determining if there’s sufficient interest in the marketplace to warrant filing a patent application.  However, at the early stages, it’s often not known whether an invention is valuable enough to pursue foreign protection, so it’s generally a good idea to get the U.S. patent application on file before undertaking such activities, as RPG Photonics did, to keep the option open. 

 

Tags: , ,

GaN LED with active region near antinode; Lightwave Photonics, Inc.; U.S. Pat. No. 7,915,624

U.S. Patent No. 7,915,624, issued on March 29, 2011 to Lightwave Photonics, Inc. of Encinitas, CA, discloses an epitaxially-grown LED having its active region in proximity to an antinode between two mirrors.

 

According to the ’624 patent, standard Group III-nitride (e.g., GaN) semiconductor LEDs suffer from low light extraction efficiencies due to the reflections at the semiconductor/air interface.  The LED structure disclosed by the ’624 patent has its active region at an antinode (e.g., maximum) of the standing optical wave in the resonant cavity between an epitaxially-grown metal mirror and another mirror.  This structure is advantageously “less process intensive and more easily commercialized” than conventional LED structures, and can avoid various problems, such as defects and cracks. 

According to its website, Lightwave Photonics is “an early stage Light Emitting Diode (LED) Chip company” developing “proprietary and patent pending technology for low cost ultra high brightness green, blue and white LEDs.”  The company has received funds from the California Energy Commission to develop its technology, including $95,000 received in 2010 to study increasing the light extraction efficiency for LEDs while reducing manufacturing costs and $200,000 received in 2009 as part of the American Recovery and Reinvestment Act.  The company owns two U.S. patents, including the ’624 patent, according to the USPTO database.

 
Comments Off

Posted by on April 27, 2011 in light emitting diode

 

Tags: , ,

Buffer structure for LED; Cree, Inc.; U.S. Pat. No. 7,872,268

U.S. Patent No. 7,872,268, issued on January 18, 2011 to Cree, Inc. of Durham, NC, discloses an LED with an AlGaN/GaN buffer structure.

 

According to the ’268 patent, silicon carbide is an attractive material to use as a substrate for the growth of bulk Group III nitrides (such as gallium nitride), since it can be conductively doped and has various desirable properties, such as a wide bandgap, a high melting point, a high thermal conductivity, and a high breakdown electric field.  When silicon carbide is used as a growth substrate for Group III nitrides, the mismatch between the lattice constants of the two materials can be ameliorated using one or more intermediate “buffer” layers between the two to minimize the number of unwanted defects in the grown layer.  The ’268 patent discloses a particular structure for such a buffer layer comprising a thin, discontinuous layer of AlGaN on the substrate and a relatively thick layer of GaN on the discontinuous AlGaN layer.

According to its website, Cree is “leading the LED lighting revolution … through the use of energy-efficient, environmentally friendly LED lighting.”  I first heard about Cree, based in Durham, NC, back in 1997 when I was a post-doc researcher in the Chemistry Dept. of the Univ. of North Carolina, Chapel Hill.  At that time, the company was creating a significant buzz with its advances in growing high-quality silicon carbide wafers and developing high-power microwave transistors and blue LEDs.  Now the company’s product line extends to high-brightness LEDs for general illumination, and has grown to have $867 million in revenues in 2010.  Cree has an interesting blog that publicizes its efforts in the “LED lighting revolution.”

According to the USPTO database, Cree received 103 U.S. patents in 2010, compared to 70 in 2009 and 71 in 2008. 

 

 
 

Tags: , ,

 
Follow

Get every new post delivered to your Inbox.

Join 47 other followers