The US Court of Appeals for the Federal Circuit affirmed a Patent Trial and Appeal Board (PTAB or Board) decision finding the challenged claims obvious over a single prior art reference owned by the patent owner, notwithstanding the patent owner’s argument that the prior art had shortcomings. Idemitsu Kosan Co., Ltd. v. SFC Co. Ltd., Case No. 16-2721 (Fed. Cir., Sept. 15, 2017) (O’Malley, J).

Idemitsu is the owner of a patent that claims a device containing a specific organic medium layered between an anode and cathode; when a voltage is applied through the electrodes, the organic medium emits light. Idemitsu is also the assignee of a prior art reference (Arakane) that teaches an organic electroluminescence device where the organic light-emitting medium layer “has a mixture layer containing (A) at least one hole transporting [HT] compound and (B) at least one electron transporting [ET] compound and the energy gap Eg1 of the [HT] compound and the energy gap Eg2 of the [ET] compound satisfy the relation Eg1<Eg2.”

SFC petitioned for, and the PTAB instituted, inter partes review of certain claims as obvious over Arakane. The PTAB found that the instituted claims were obvious because the patent’s claimed formula compounds corresponded to the HT and ET formulas disclosed in Arakane, and Arakane further teaches that the light-emitting layer can be formed by combining the HT and ET compounds. Idemitsu appealed.

On appeal, Idemitsu argued that the PTAB erroneously assumed (1) that a skilled artisan would have expected that all of the HT compounds disclosed in Arakane have a lower energy gap than all of the disclosed ET compounds, or (2) that Arakane suggests combinations of HT and ET compounds that do not satisfy the energy gap relation in addition to combinations that do satisfy the energy gap.

The Federal Circuit affirmed the PTAB, finding substantial evidence to support its conclusion that Arakane teaches that a light-producing device can be made by combining the HT and ET compounds, regardless of any shortcomings in durability or resistance caused by an imperfect energy gap ratio. The Court also noted that the instituted claims do not include any limitations directed to the energy gap characteristics of the individual components or particular performance characteristics of the light-emitting layer. The Court also found that the Arakane disclosure would have informed a skilled artisan that combining the disclosed HT and ET compounds would produce a light-emitting layer.