Philips Asserts “Liquid Hues” and “Luminaire” LED Patents Against Lighting Science


Dutch Electronics giant Koninklijke Philips Electronics NV (Philips) opened a new front against Lighting Science Group Corp. (LSG), accusing the Dallas-based lighting products maker of infringing two patents covering LED technology. 

Philips’ bare bones complaint (philips_complaint.pdf), filed last month in federal district court in Massachusetts, asserts U.S. Patent Nos. 6,967,448 (‘448 patent) and 6,250,774 (‘774 patent) and names no specific LSG products.

The ‘448 patent, entitled “Method and apparatus for controlling illumination,” relates to LED lighting systems that can generate variable color radiation without the use of color filters.  The patented technology is designed for underwater lighting such as in pools or spas.

According to the ‘448 patent, liquids significantly absorb and scatter certain colors such that the colors look different under water than they do when projected in air.  The patent discloses a method for generating “liquid hues” that adjust for this effect so that the appearance of LED colors in water approximates similar colors in air.

The system of the ‘448 patent uses a controller that adjusts the individual intensity of each differently colored LED to control the overall radiation output of the lighting system.

One interesting point about the ‘448 patent is that it is part of an extremely long chain of continuation and continuation-in-part parent applications, dating back to 1997 (the ‘448 patent issued in 2005).  I counted about 18 parent applications listed on the face of the ‘448 patent.  This lengthy history should provide LSG’s lawyers with plenty of ammunition for the company’s defense.

The ‘774 patent is entitled “Luminaire” and is directed to an LED package for street lighting that uses the generated light more efficiently.  According to the patent, a major disadvantage of some existing luminaires is that the light doesn’t concentrate well into a beam and therefore a substantial percentage of the light projects outside the area or object to be illuminated.


The patented technology solves this problem and reduces energy use by focusing the individual beams of multiple LED lighting units such that each narrow beam only hits a portion of the area or object.  The claimed luminaire (1) (shown above) has a housing (10), a light emission window (11) and a set of lighting units (20), each having at least one LED chip (30) and an optical system (40), with the lighting units illuminating respective portions of an object.

Philips and LSG are engaged in other LED technology battles:  Philips filed another patent infringement suit against LSG in Massachusetts in February involving five other LED patents, and in March LSG accused Philips of misappropriating proprietary technology in a case pending in state court in California.  It looks like tensions may be brewing between these two for a while.

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Eric Lane

Eric Lane, the founder and principal of Green Patent Law, is an intellectual property lawyer and registered U.S. patent attorney in New York and is a member of the bar in New York and California. Eric has more than two decades of experience working with wind, solar PV, CSP, biofuels, and geothermal, energy storage technologies, carbon capture and sequestration, medical devices, data communications, mechanical, chemical, internet and software.