In affirming a finding of obviousness by the U.S. Patent and Trademark Office, Board of Patent Appeals and Interferences (the Board), the U.S. Court of Appeals for the Federal Circuit found that the disclosure of a preferred embodiment in a prior art reference does not teach away from a combination of prior art references that leads to the applicant’s invention, even when the combination is described as being inferior.  In re Blaise Laurent Mouttet, Case No. 11-1451 (Fed. Cir., June 26, 2012) (Reyna, J.). 

The applicant’s invention is directed to an arithmetic processor that included a nanoscale crossbar array of intersecting electrical wires with molecular switches formed at different intersections or “crosspoints.”  During prosecution, the examiner rejected the application claims, relying on a combination of three prior art references, including a patent issued to Falk.  Falk disclosed an arithmetic processor device similar to applicant’s processor, except that Falk’s device included a crossbar array having intersecting optical channels with programmable switches based on optical intensity, rather than electrical wires and programmable switches based on electrical conductivity. The other two references included a publication by Das that disclosed a nanoscale crossbar array of electrical wires and a patent issued to Terepin that disclosed an analog-to-digital converter, a necessary component of Mouttet’s device.  After the Board affirmed the examiner’s rejections, the applicant appealed. 

On appeal, applicant argued that substituting Falk’s optical channels with electrical wires would destroy the principle of operation and physical structure of Falk’s device and that Falk teaches away from an electrical crossbar array. 

The Federal Circuit affirmed the Board’s determination that substituting Falk’s optical channels with electrical wires would not destroy its principle of operation was supported by substantial evidence.  The Court also found that the nonequivalence of substituted elements is irrelevant, because obviousness determinations do not require “an actual, physical substitution of elements.” 

The Court also found that the Board’s determination that Falk’s description of a preferred embodiment did not “teach away” was supported by substantial evidence, despite the fact that Falk described a “fundamental difference” between optical versus electrical circuits and “even suggests that electrical circuits are an [sic] inferior to optical circuitry for certain purposes.”  The Court explained that this was not a sufficient reason to overturn the Board’s determination as applicant failed to cite to any evidence suggesting the claimed invention would be unlikely to work using electrical circuitry.  The Court further emphasized that a known system, like the invention in this case, “does not become patentable simply because it has been described as somewhat inferior to some other product for the same use.”

Practice Note:  In order to support a “teaching away” argument, a reference should provide a strong indication that the claimed subject matter or proposed combination would be unlikely to work or operate as intended.