A Green Patent Complaint Update from fall 2014 discussed one of the patent lawsuits between Cree and Harvatek in which Cree asserted several patents relating to white light LED technology.
One of those patents – U.S. Patent No. 6,600,175, entitled “Solid state white light emitter and display using same” (‘175 Patent) – was the subject of an ex parte reexamination proceeding in the U.S. Patent and Trademark Office (USPTO).
During the reexam, Cree added six claims to the patent. The new claims at issue are directed to the production of white light through “down-conversion” of blue light from LEDs. Down conversion means absorbing high energy (shorter wavelength) light and re-emitting it as lower energy (longer wavelength) light to produce light of a desired wavelength, i.e., color.
The patent examiner rejected those claims as obvious over multiple combinations of prior art references including three particular patent references, and the USPTO’s Patent Trial and Appeal Board (PTAB) affirmed the examiner’s reasoning and conclusion.
In a recent decision, the U.S. Court of Appeals for the Federal Circuit, showing much deference to both the examiner and the PTAB, rejected all of Cree’s arguments on appeal and affirmed the PTAB’s obviousness holding.
The claims of the ‘175 Patent at issue recited an LED having a “down-converting luminophoric medium for down-converting the radiation emitted by the light-emitting diode to a polychromatic white light…” In lighting applications, luminophoric materials are commonly called phosphors.
The primary prior art references were the Pinnow patent, which discloses a display system that creates black and white images using a blue laser and appropriate phosphors and explains how to make white light by down conversion; the Stevenson patent, which discloses LED light that may be converted to lower frequencies with good conversion efficiency using organic and inorganic phosphors; and the Nakamura patent, which discloses a gallium nitride (GaN) LED that emits a blue light that was brighter than similar, previously developed LEDs.
In the reexam, the examiner found it would have been obvious to substitute the LED of Stevenson with either the known UV light emitting or blue light emitting GaN-based LED in Nakamura, and this would be a simple substitution of one known element for another to gain the predictable result of brighter emission by the phosphors.
The PTAB agreed with the examiner’s reasoning and conclusion that the combination of Stevenson, Pinnow, and Nakamura rendered the ‘175 Patent claims obvious:
[T]he combined teachings of Stevenson, Pinnow, and Nakamura would have suggested to an artisan of ordinary skill to use a blue LED on a single die to create white light via “down-conversion” because Nakamura’s blue LED is more powerful than Stevenson’s older, less-efficient LED in terms of power and brightness and, as such, is more suitable with a “down-conversion” process to product white light…
According to the PTAB, the invention of the ‘175 Patent is “nothing more than a new application of a high-power, high-brightness blue LED developed by Dr. Nakamura in late 1993.”
The Federal Circuit opinion does not add much analysis to that of the patent examiner and the PTAB. Rather, it is essentially a series of refutations of Cree’s arguments on appeal. Throughout, the appeals court consistently defers to the PTAB’s conclusions.
In response to Cree’s contention that the Board erred by by assuming that it was disclosed in a single prior art reference (Pinnow) to make white light from a monochromatic LED through down conversion, the court said Pinnow provided, according to the Board, a general disclosure of down conversion for creating white light, which was “a perfectly reasonable conclusion.”
Cree also argued that the Board misread the declarations of Cree’s experts. Again, the Federal Circuit found the conclusion the Board drew from the expert testimony that down conversion was a known solution for generating white light from a blue LED was “reasonable” and “supported by substantial evidence.”
Cree further argued that neither the examiner nor the Board articulated a rational motivation to combine the teachings of Pinnow, Stevenson, and Nakamura. The court again disagreed, finding the Board “provided a sufficient, non-hindsight reason to combine the references.”
Perhaps one lesson here, though not really news, is to make sure to present all of your best arguments and evidence in the lower tribunals and not count on the appellate process to bail you out.