Corresponding "Means" Structure May Perform Additrional Function

In Engineered Products, Co. v. Donalson Co., Inc. (Fed. Cir., August 31, 2005, nonprecedential), the court agreed with Donaldson that the district court erred in its construction of a means-plus-function limitation by not identifying all of the structure necessary to perform the stated function in U.S. Patent No. 4,445,456, below.
In this case, the claims at issue contained the limitation "means for selectively disengaging the interengagable notches so as to permit the diaphragm to return to its infold position when the vacuum in the first chamber is relatively low." The court noted that specification of the patent states

When it is desired to reset the indicator after cleaning or replacement of the
air filter and after the member has been locked up, . . . the thumb of the
operator . . . is pressed against the button to move the member from its
off-center position to a vertical dotted line position by reason of the
cooperation between the flange and the bottom wall and the enlarged hole . . .
to release the notches and . . . permit [the] spring to return the indicating
assembly to its lower home position . . . .

****

If it is desired to permit the diaphragm to return to its infold position, . . . a person need only push the button . . . against the bias of [the] spring. This will cause the
locking member to pivot, about the flange, from its cocked, off-center position,
. . . to a vertical position where the notches can no longer engage the notches.

According to the Federal Circuit, this portion of the specification clearly links the button, flange, bottom wall, and enlarged opening to the function of disengaging the interengagable notches:

It is true that an individual initiates the process of disengaging the notches by pushing the button located at the bottom of the chamber. However, it is the
resulting action of the flange against the bottom wall that actually causes the
interengagable notches to disengage. See Cardiac Pacemakers, Inc. v. St. Jude Med., Inc., 296 F.3d 1106, 1119 (Fed. Cir. 2002) ("It remains true, of course, that corresponding structure need not include all things necessary to enable the claimed invention to work. It is equally true, however, that corresponding structure must include all structure that actually performs the recited function." (emphasis added)).

Our construction also does not read in a functional limitation of "pivoting." It is
true that the flange, as disclosed in the specification, pivots about the bottom wall to cause the locking member to disengage the interengagable notches. However, corresponding structure will almost always perform some additional function in the course of executing the claimed function. See, e.g., Kemco Sales, Inc. v. Control Papers Co., 208 F.3d 1352, 1359-63 (Fed. Cir. 2000) (holding that the corresponding structure was not just a "flat rectangle, but a plastic flap that folds over [an] envelope’s opening and is secured to the outside of one or both panels of the envelope" (emphasis added)). In this case, the pivoting of the flange on the bottom wall is simply how the flange operates to disengage the locking member from the notches.

Under our construction, we further conclude that a reasonable juror could not find that the NG Air Alert infringes claims 2 or 3 of the ’456 patent. See Genthe v. Lincoln, 383 F.3d 713, 716 (8th Cir. 2004) ("Judgment as a matter of law is appropriate where the evidence adduced at trial is entirely insufficient to support the verdict."). That is because, even assuming the NG Air Alert has structure that performs the function of "selectively disengaging interengagable notches," that structure is not the same or equivalent to the corresponding structure of claims 2 and 3—namely, the flange, bottom wall, and enlarged opening. See Frank’s Casing
Crew, 389 F.3d at 1378 ("Th[e] inquiry for equivalent structure under § 112, ¶ 6 examines whether ‘the assertedly equivalent structure performs the claimed function in substantially the same way to achieve substantially the same result as the corresponding structure described in the specification.’" (citation omitted)).

In particular, instead of a flange that works in conjunction with a bottom wall to cause the locking member to tilt back toward the vertical position and disengage the
interengagable notches, the accused structure consists of flared fingers that
are pushed inward when the operator of the NG Air Alert pushes a button.
Therefore, the flared fingers of the NG Air Alert perform the claimed function
in a substantially different way than the flange and bottom wall of claims 2 and
3. Accordingly, we reverse the district court’s decision denying Donaldson’s
motion for JMOL of non-infringement and remand with instructions to enter
judgment for Donaldson of non-infringement by the NG Air Alert.