PTAB

IPR2015-00744

Kingbright Electronics Co Ltd v. Cree Inc

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Light Emitting Assembly
  • Brief Description: The ’945 patent discloses a light emitting assembly that generates white light. The assembly uses a light emitting diode (LED), particularly a blue LED, that emits radiation to excite a "luminophoric medium" (such as a phosphor), which in turn down-converts the radiation and emits a range of wavelengths that combine with the LED's light to produce a white light output.

3. Grounds for Unpatentability

Ground 1: Obviousness over Applicant Admitted Prior Art and Tabuchi - Claims 19, 20, and 30-41 are obvious over Applicant Admitted Prior Art (AAPA) alone or in view of Tabuchi.

  • Prior Art Relied Upon: AAPA (statements from the patent specification and related prosecution/reexamination files) and Tabuchi (Japanese Patent No. JP 50-79379).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the patent owner’s own admissions (AAPA) establish the key elements of the claims as known prior art before the invention date. Specifically, AAPA disclosed using blue LEDs (including GaN-based LEDs emitting at ~450 nm), the principle of down-conversion to create white light using phosphors, and co-packaging LEDs with fluorescent materials in a polymer housing. For example, AAPA acknowledged commercially available Nichia blue LEDs and the use of Lumogen® dyes for down-conversion. Tabuchi was introduced to teach specific configurations of the luminophoric medium, such as coating it on an interior or exterior surface of a transparent enclosure surrounding the LED die, thereby satisfying limitations in independent claim 30 and its dependents.
    • Motivation to Combine (for §103 grounds): Petitioner asserted that a person of ordinary skill in the art (POSITA) would combine the elements disclosed in AAPA because they represent foundational, well-known principles for creating white light. A POSITA would have looked to known packaging and phosphor arrangement techniques, such as those in Tabuchi, as simple and predictable design choices to implement the white LED concept disclosed in the AAPA. The combination was argued to be a straightforward application of known elements to achieve a predictable result.
    • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success because the underlying principles of fluorescence and wavelength conversion were well-understood, and the components (blue LEDs, phosphors, encapsulants) were commercially available and known to be compatible.

Ground 2: Obviousness over Stevenson, Pinnow, and AAPA - Claims 19, 20, and 30-41 are obvious over Stevenson in view of Pinnow and AAPA.

  • Prior Art Relied Upon: Stevenson (Patent 3,819,974), Pinnow (Patent 3,691,482), and AAPA.

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground presented an alternative combination of statutory prior art. Stevenson taught a GaN semiconductor LED that emits blue light and disclosed using phosphors to convert light to different colors. Pinnow taught using mixtures of phosphors (including inorganic YAG:Ce) to down-convert blue light to achieve "true white" light and taught mixing primary and secondary emissions to achieve a desired chromaticity. The AAPA references (disclosing high-brightness, high-power Nichia blue LEDs) were used to supply the high-brightness LED element, which Petitioner argued was a known improvement in the art that a POSITA would naturally incorporate.
    • Motivation to Combine (for §103 grounds): A POSITA, starting with Stevenson's blue-emitting GaN LED, would be motivated to improve its output to create a high-quality white light source. Pinnow provided the explicit teaching of using phosphor mixtures to achieve "true white" light from a blue source. A POSITA would combine these teachings to create a more efficient and commercially desirable white light product. The high-brightness blue LEDs from AAPA represented a known, superior light source that a POSITA would have been motivated to use in place of older LEDs to improve overall device performance.
    • Expectation of Success (for §103 grounds): The combination was portrayed as predictable, as both Stevenson and Pinnow operated on the same well-understood principles of photoluminescence, and combining them with a more powerful, state-of-the-art LED (from AAPA) would be expected to yield a brighter white light.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations including Tadatsu (Japanese Patent No. JP 5-152609), Candela (a 1994 physics letter), Nakamura (Patent 5,578,839), van Kemenade (Patent 4,727,283), Imamura (Patent 5,283,425), and Lenko (Patent 4,915,478), but relied on similar arguments of combining known high-brightness blue LEDs with various known phosphor materials and configurations to achieve the predictable result of white light.

4. Key Claim Construction Positions

  • "luminophoric medium": Petitioner proposed this term be construed as "a phosphor, a fluorescer, a luminescent dye or combination thereof that converts electromagnetic radiation by absorbing radiation of one wavelength and emitting a blend of wavelengths...that appear white to a human." This construction was argued to be consistent with the specification's definition, which describes the medium as a "down-converting material" comprising fluorescers and/or phosphors. The construction was critical to Petitioner's argument that the prior art’s disclosure of various phosphors and dyes met this limitation.

7. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 19, 20, and 30-41 of the ’945 patent as unpatentable under 35 U.S.C. §103.