However, as noted in the dissent by Judge Newman, other parts of the specification describe the flutes working in conjunction the perforated pipe to ensure that sufficient air will be present in the material to achieve complete decomposition. In her view, the applicant's "belief" statement in the specification did not require the air channels and was not the invention that was patented.
In most places the specification describes the invention as including both flutes and perforated pipe, and the drawings show both flutes and perforated pipe. Specifically, the abstract states that "[t]he presence of air in the channels created by the flutes and the air present in the perforated pipe ensures that sufficient air will be present in the mass to achieve complete decomposition of the material." The specification further states that "[t]he air present in the grooves in the material [i.e., the flutes] and the air present in the perforated pipe causes the material to properly decompose." However, the specification also points out that both structures are not required, stating: "[I]t is believed that sufficient air will be present to achieve decomposition with either the channels 48 or the perforated pipe 50 although it is preferred that both the flutes 46 and the pipe 50 be utilized." We conclude that, in light of this disclosure, flutes are not essential.
Moreover, here the language of the claim itself also suggests that the means for creating air channels does not have to include flutes. After setting forth the "means . . . for creating air channels" limitation, that limitation is further defined by the next clause of the claim, which reads: "said means for creating air channels comprising positioning means which positions at least one elongated, perforated pipe . . . ." Although "comprising" language is not limiting and may include features not recited in the claim, such language cannot be read to require other structure. Thus the claim language itself shows that flutes are not required structure for the "means . . . for creating air channels."
Furthermore, the doctrine of claim differentiation supports the conclusion that flutes are not necessary structure. The doctrine of claim differentiation "create[s] a presumption that each claim in a patent has a different scope." The difference in meaning and scope between claims is presumed to be significant "[t]o the extent that the absence of such difference in meaning and scope would make a claim superfluous." Here, claim 2 of the â€™910 patent depends from claim 1 and adds that flutes are "also" present:2. The machine of claim 1 wherein said tunnel means has inner and outer surfaces and wherein said means for creating air channels also comprises spaced-apart inwardly projecting flutes positioned on the inner surface of said tunnel means.
The specification, drawings, and prosecution history all teach that a material aspect of the device is the air channels or grooves created by the plurality of flutes. The patentee may have "believed" that some other structure could achieve decomposition, but that is not what was presented for examination.
So what's a patent practioner to do, you ask? I say, use as much "claim-type differentiation" as possible and hope like hell that you never have to bet your career on a means-plus-function claim.
Click here anytime to listen to a rebroadcast of the November 2003 APLF Roundtable Event on "Structure, Function, and the Importance of Claim-Type Differentiation." The PowerPoint materials are available here. You'll also need RealPlayer installed on your computer.
And, of course, feel free to contact me for an in-person presentation of these materials to your patent organization.