A reference’s specific contribution to the art beyond its more conventional features may be used to characterize its “principle of operation” in considering whether such functionality would be preserved by an otherwise obvious modification. Here, for example, a reference’s disclosure of a specialized set of valves and pumps designed to prevent backflow was found to be central to its principle of operation and therefore not readily replaceable by other components for the purposes of establishing obviousness. “Such a change in a reference’s ‘principle of operation’ is unlikely to motivate a person of ordinary skill to pursue a combination with that reference.” This would be a good case to consult and cite in response to an asserted modification for obviousness purposes that would destroy the specific inventive functionality of the prior art being modified.
Background / Facts: The patent on appeal here from an inter partes affirmance by the PTO is directed to a device and methods for mixing and dispensing multi-component paints. The prior art identified by the third party requestor discloses pumps, check valves, stop valves, and escape valves that the PTO deemed essential to its “principle of operation,” i.e., “prevent[ing] backflow even when the propensity for backflow occurs repeatedly and at high velocity.” Because the third party requestor’s proposed combination of the prior art would fail to preserve this principle of operation, the PTO declined to find the corresponding claims obvious.
Issue(s): Whether the PTO erred by limiting the prior art’s “principle of operation” to its specific contribution to the art, i.e., the addition of stop valves to prevent backflow.
Holding(s): No. “The manner in which the two-component mixing apparatus of [the first reference] prevents backflow is unique in its implementation [], and the Board correctly limited [its] ‘principle of operation’ to that specific functionality. Therefore, replacing the valves and pumps of [the first reference’s] system with the cylindrical cartridges and mixing gun of [the second reference], which fail to achieve comparable backflow prevention, … fundamentally alters [the first reference’s] ‘principle of operation.’ Such a change in a reference’s ‘principle of operation’ is unlikely to motivate a person of ordinary skill to pursue a combination with that reference.”