A naturally implemented solution to a known problem is likely obvious. Here, for example, a periodic fan cycle that starts with an ‘off’ period rather than an ‘on’ period following the deactivation of a main heating or cooling cycle was found to be “naturally implemented” and “nearly obvious” from just the air stagnation problem described in the prior art. “It is well settled that, even where references do not explicitly convey a motivation to combine, any need or problem known in the field of endeavor at the time of invention and addressed by the patent can provide a reason for combining the elements in the manner claimed.” It may therefore be helpful when drafting the specification to frame the problem being addressed in a way that differs from what might be already recognized in the field.
Background / Facts: The patent being asserted here is directed to a forced central air system with a “recycle control” for periodic fan operation when the system is not heating or cooling. The periodic fan operation begins “a preselected time period” after the fan stops at the end of a heating or cooling cycle, or after the termination of “constant fan mode” operation. The parties agree that the primary reference addresses the same problem identified by the patent (i.e., air stagnation during periods without heating or cooling) and sets forth every limitation of asserted claim 1 except for tying periodic fan cycles directly to the deactivation of the heating or cooling elements or to the end of “constant mode” operation.
Issue(s): Whether it would have been obvious to modify the primary reference’s periodic fan cycles to start with an ‘off’ period rather than an ‘on’ period following the deactivation of a main heating or cooling cycle.
Holding(s): Yes. “In our view, if, at the time of the invention claimed in the [] patent, a person of ordinary skill had looked at [the primary reference], he or she would have found it nearly obvious from that disclosure itself to set the periodic fan to run as a function of when the heating or cooling cycle ended. That is because the nature of the problem to be solved in both the [] patent and [the primary reference] is to alleviate air stagnation during periods of no heating or cooling. As [an expert] testified, ‘a person of ordinary skill would realize that the easiest and best thing to do would be to start with an off period, a delay before doing this cycling since the purpose is to mix the air and the air has just been mixed.’ [] Thus, setting a delay timer or control based on the end of the heating or cooling cycle, similar to the concept in [other cited references], would have been naturally implemented by a person skilled in the art.”