             NOTE: Pursuant to Fed. Cir. R. 47.6, this disposition is not
             citable as precedent. It is a public record.

 United States Court of Appeals for the Federal Circuit


                                        05-1319

                               KWIK PRODUCTS, INC.,

                                                       Plaintiff/Counterclaim Defendant-
                                                       Appellant,

                                           and

                  FERNANDO R. IACONA and IGNAZIO M. IACONA,

                                                       Counterclaim Defendants-Appellees,

                                            v.

        NATIONAL EXPRESS, INC., CMD PRODUCTS, GEORGE E. ALLISS,
              ALEX J. PHINN, JR., GRIFF AND ASSOCIATES, L.P.,
                             and TORVIAN, INC.,

                                                       Defendants/Counterclaimants-
                                                       Appellees.

                               _____________________

                               DECIDED: April 26, 2006
                               _____________________

Before MICHEL, Chief Judge, MAYER and LOURIE, Circuit Judges.

LOURIE, Circuit Judge.

      Kwik Products, Inc. (“Kwik”) appeals from the judgment of the United States

District Court for the Southern District of New York of noninfringement of U.S. Patent

5,896,666 in favor of National Express, Inc., CMD Products, George E. Alliss, Alex J.

Phinn, Jr. and Griff and Associates, L.P., and Torvian, Inc (collectively “Torvian”). Kwik
Prod., Inc. v. Nat’l Express, Inc., No. 03-9291 (S.D.N.Y. March 29, 2006) (“Final

Judgment”). Because the district court correctly construed the claim limitation “clamping

means” and did not clearly err in finding no literal infringement of claim 1 and no

infringement of claim 15 under the doctrine of equivalents, we affirm.

                                     BACKGROUND

        Vegetation trimmers are outdoor power tools used to cut grass, weeds, and other

vegetation, and feature a replaceable head that spins a blade or string at speeds up to

10,000 rpm. Kwik Prod., Inc. v. Nat’l Express, Inc., 356 F. Supp. 2d 303, 305 (S.D.N.Y.

2005) (“Opinion”). The ’666 patent, entitled “Head for String Trimmer,” assigned to

Kwik, is directed to a vegetation trimmer head that can be easily reloaded. Independent

claim 1 discloses a combination of a cutting head and string for cutting and trimming

vegetation comprising at least one generally straight length of string, a cutting head, and

a clamping means for fixing the string to the head. ’666 patent, col. 6, ll. 37-55. Claim

2, which depends from claim 1, adds the limitation that the clamping means include a

pivotally mounted clamping member and a pressing wall aligned to cooperatively clamp

the string. Id., col. 6, ll. 56-59. Independent claim 15, which also discloses a cutting

head for a string trimmer, requires a clamping member that is pivotally mounted and

urged by a spring in a clockwise direction around a pivot post against an opposing wall.

Id., col. 8, ll. 18-44.

        As illustrated in Figure 3, the clamping member (36), which is a cam in this

embodiment, rotates on the pivoting post (38), pressing the string (14) against the

pressing wall (32). The center of gravity of the cam is denoted by the letters “CG” and a




05-1319                                  2
spring (40) biases the cam so that it will rotate in a certain direction. The spring has one

end secured to the cam and the other end secured to a bracket in the side wall.




       Kwik began manufacturing the commercial embodiment of the ’666 patent in

1998. Opinion, 356 F. Supp. 2d. at 308. In 2000, George Allis developed a competing

vegetation trimmer head. Id. at 309. Allis’s device used a spring-biased, slideable

clamping member with a compression spring to hold straight lengths of trimmer string in

place. Id. On June 24, 2003, the U.S. Patent and Trademark Office (“PTO”) issued

U.S. Patent 6,581,292, entitled “Vegetation Trimmer Apparatus,” covering Allis’s

invention. Id. at 309-10. Torvian later marketed its commercial embodiment of that

invention as the “Grass Gator Load n’ Cut.” Id. at 310.

       On November 21, 2003, Kwik filed suit against Torvian in the United States

District Court for the Southern District of New York, alleging infringement of claims 1, 2,

and 15 of the ’666 patent. Kwik filed an amended complaint on April 28, 2004. In its

May 28, 2004, answer to the amended complaint, Torvian asserted a single

counterclaim for a declaratory judgment of invalidity and unenforceability of claims 1-10

and 15-19 of the ’666 patent. The case was tried to the district court without a jury in




05-1319                                  3
October 2004. It is undisputed that Torvian did not put in evidence on the issue of

inequitable conduct during trial.

       At the conclusion of trial, the district court, in an excellent and thorough opinion,

held that Torvian did not infringe the ’666 patent, either literally or under the doctrine of

equivalents. The court first held that 35 U.S.C. § 112 ¶ 6 applied to claim 1 so that

“clamping means” was limited to “a spring element working with a pivotally mounted

clamping member with a strategically placed center of gravity.” Id. at 318-19. Second,

relying on the specification, the court construed “spring” in claim 15 as referring to an

“extension or torsion spring.” Id. at 319. The court then determined that the Allis device

did not literally infringe the asserted claims because it did not use a pivotally mounted

clamping member or rely on a strategically placed center of gravity. Id. The court also

found that the Allis device did not infringe the asserted claims under the doctrine of

equivalents because it did not meet four limitations of the ’666 patent: a pivotally-

mounted clamping member, rotational movement of the clamping device, a clamping

member in which the location of the center of gravity was significant, and a spring

attached to the cam and the other to a side wall. Id. at 320. The court observed that

the Allis device used a slideably-mounted clamping member, a linear sliding motion, a

clamping force that was not influenced by the center of gravity, and an unattached

compression spring. Id.

       As to invalidity, the court held that claims 1-10 and 15-19 were not anticipated or

rendered obvious by prior art. Id. at 322-23. The court found that none of the prior art

references disclosed “a spring for urging a clamping member in the direction of a

pressing wall or a pivotally mounted clamping member urged by a torsion spring and




05-1319                                   4
working together with centrifugal force to hold a straight length of spring in place.” Id. at

322. The court also concluded that it would not have been obvious to one of ordinary

skill in the art to modify one or more of the prior art references to use “a spring biased,

cam shaped, pivotally mounted clamping member to hold a fixed length of string in

place in a trimmer head rotating at 10,000 rpm.” Id. at 323. The court pointed out that

“though some of the prior art references had existed for many years, there still was a

long-felt need for a convenient and easy-to-load trimmer head as late as the 1990s.” Id.

       On February 24, 2005, the court entered a judgment dismissing Kwik’s claims for

patent infringement and dismissing Torvian’s “counterclaim for invalidity.” Judgment,

slip op. at 1. Kwik filed a Notice of Appeal on March 18, 2005, and Torvian filed a

Notice of Appeal on March 25, 2005. We determined that the district court had not

adjudicated Torvian’s unenforceability counterclaim, which rendered the district court’s

judgment nonfinal for purposes of an appeal. However, we restated the principle that “a

premature notice of appeal ripens upon subsequent action of the district court.” Kwik

Prod., Inc. v. Nat’l Express, Inc., No. 05-1319, -1343, slip op. at 4 (Fed. Cir. March 13,

2006) (quoting Pause Tech. LLC v. TiVo Inc., 401 F.3d 1290, 1295 (Fed. Cir. 2005)).

Hence, we permitted the parties to seek remedial action in the district court and move

this court to reinstate the appeal from a final judgment.

       Kwik   returned   to   the   district   court   requesting   dismissal    of   Torvian’s

unenforceability counterclaim. The court agreed to dismiss the counterclaim, and Kwik

filed an amended notice of appeal to reinstate its appeal of the court’s judgment of

noninfringement.    However, Torvian did not file an amended notice of appeal to

reinstate its cross-appeal of the court’s judgment of no invalidity.            Therefore, we




05-1319                                    5
reinstated Kwik’s appeal as to noninfringement, but not Torvian’s cross-appeal as to

invalidity.

        We now turn to the merits of Kwik’s appeal from the judgment of

noninfringement, as that judgment is final, and we have jurisdiction pursuant to 28

U.S.C. § 1295(a)(1).

                                      DISCUSSION

        Claim construction is an issue of law, Markman v. Westview Instruments, Inc., 52

F.3d 967, 970-71 (Fed. Cir. 1995) (en banc), that we review de novo, Cybor Corp. v.

FAS Techs., Inc., 138 F.3d 1448, 1456 (Fed. Cir. 1998) (en banc). The district court's

determination of infringement, in contrast, is a question of fact that we review for clear

error. Centricut, LLC v. Esab Group, Inc., 390 F.3d 1361, 1367 (Fed. Cir. 2004). “A

finding is ‘clearly erroneous’ when although there is evidence to support it, the reviewing

court on the entire evidence is left with the definite and firm conviction that a mistake

has been committed.” United States v. U.S. Gypsum Co., 333 U.S. 364, 395 (1948).

        On appeal, Kwik argues that the district court erred in holding that § 112, ¶ 6

applied to the term “clamping means” in claim 1 of the ’666 patent. According to Kwik,

because a clamp identifies a device that has a reasonably well understood meaning in

the art, “clamping means” is not a means-plus-function limitation. Kwik contends that

under the proper construction of “clamping means,” there is no limitation that it comprise

a pivotally mounted clamping member having a particularly located center of gravity, as

supported by the doctrine of claim differentiation. Kwik also argues that the court erred

in construing the term “spring” in claim 15 of the patent to be limited to extension and

torsion springs. Kwik asserts that the ordinary and customary meaning of the term




05-1319                                  6
“spring” is not limited to the specific types of springs disclosed in the specification, and

thus includes compression springs. Based on its construction of “clamping means” and

“spring,” Kwik contends that claim 1 is literally infringed and claim 15 is infringed under

the doctrine of equivalents.    Kwik points out that the slideably mounted clamping

member of the accused device is equivalent to the pivotally mounted clamping member

recited in claim 15 of the patent because it performs the same function (to clamp the

string), in the same way (by being urged toward the opposed way under a spring force),

to achieve the same result (fixing the string in the trimmer head).

       Torvian responds that the district court correctly applied § 112, ¶ 6 to the term

“clamping means” because the claim is written in classic means-plus-function format,

and Kwik failed to rebut the presumption that § 112, ¶ 6 applies. According to Torvian,

the court correctly limited “clamping means” to the structures identified in the

specification: a pivotally-mounted clamping member, either biased by a torsion or

extension spring against an opposing wall or completely unbiased (in which event the

force is applied manually), and a strategically-placed center of gravity, which increases

the clamping force while the trimmer head is spinning. Torvian also contends that the

court correctly relied on the specification to construe the term “spring” as a torsion or

extension spring, but not a compression spring because the patent’s reference to a

“generic” spring is ambiguous. Finally, Torvian argues that the accused device does not

infringe claims 1 and 15 of the patent, either literally or under the doctrine of

equivalents, because it contains a slideably-mounted clamping member, biased by a

compression spring, whose clamping force is not influenced by the location of its center

of gravity.   Torvian points out that the accused device not only contains different




05-1319                                  7
structures from those disclosed in the ’666 patent, but also functions in a different way,

such that the force applied to hold the cutting string in place is applied rectilinearly

rather than through circular or rotational application of force.

       We agree with Torvian that the district court correctly construed the term

“clamping means” in claim 1 as a means-plus-function limitation. A claim using the

means-plus-function format will cover only the corresponding structure disclosed in the

written description, as well as that structure's equivalents. 35 U.S.C. § 112, ¶ 6;

Personalized Media Commc’n, LLC v. Int'l Trade Comm'n, 161 F.3d 696, 703 (Fed. Cir.

1998). A claim limitation that actually uses the word “means” will invoke a rebuttable

presumption that § 112, ¶ 6 applies. Id. at 703-04. In this case, claim 1 phrases the

“clamping means” limitation in means-plus-function language, thereby triggering the

presumption. Because Kwik has not rebutted that presumption, the claim must “be

construed to cover corresponding structure, material, or acts described in the

specification and equivalents thereof.” 35 U.S.C. § 112, ¶ 6.

       Here, the specification of the ’666 patent discloses a “clamping member [that] is

pivotally mounted adjacent each aperture, opposite the corresponding pressing wall so

that its center of gravity is disposed between the pivotal mounting and the

corresponding pressing wall.” ’666 patent, col. 3, ll. 4-7. Further, as the district court

correctly observed, the specification refers to “two degrees of clamping force,” one that

is generated by springs that hold the string in place when the cutting head is not in use

and a second that is generated when the cutting head rotates and creates a centrifugal

force “that acts on the centers of gravity of the clamping members and enhances the

gripping force thereof.” Id., col. 3, ll. 7-17. Therefore, the court did not err in construing




05-1319                                   8
the means-plus-function limitation “clamping means” to mean “a spring element working

with a pivotally mounted clamping member with a strategically placed center of gravity.”

Opinion, 356 F. Supp. 2d at 318.

       We reject Kwik’s argument that the well understood meaning of “clamp” rebutted

the presumption that § 112, ¶ 6 applies to the limitation “clamping means.”        Even

assuming that the term “clamp” had a reasonably well understood meaning in the art, a

clamp is not the same as a clamping means. Equally unpersuasive is Kwik’s argument

that claim differentiation requires a different interpretation of “clamping means.” As we

stated in Laitram Corp. v. Rexnord, Inc., 939 F.2d 1533 (Fed. Cir. 1991), “[a] means

plus function [element] is not made open-ended by the presence of another claim

specifically claiming the disclosed structure which underlies the means clause or an

equivalent of that structure.” Id. at 1538. We further stated that “one cannot escape

[the] mandate [of § 112, ¶ 6] by merely adding a claim or claims specifically reciting

such structure or structures.” Id. Because we conclude that § 112, ¶ 6 applies to the

limitation “clamping means” in claim 1, we do not address Kwik’s remaining arguments

as to the construction of that term.

       Having affirmed the district court’s claim construction of the term “clamping

means,” we also affirm its judgment of no literal infringement of claim 1.        Kwik’s

argument that there was literal infringement of claim 1 depends entirely upon a finding

that the term “clamping means” is not a means-plus-function limitation. Because § 112,

¶ 6 does apply to that term, the court made no clear error in determining that the

accused device did not literally infringe claim 1 of the ’666 patent.




05-1319                                   9
       We also affirm the district court’s judgment of no infringement of claim 15 under

the doctrine of equivalents. As an initial matter, we note that we do not reach the issue

of the correct interpretation of the term “spring” in claim 15 because the district court’s

determination of noninfringement under the doctrine of equivalents does not rely solely

upon its construction of that term. Even under Kwik’s proposed construction of “spring”

as including compression springs, the court made no clear error in finding that the

accused device did not perform substantially the same function in substantially the

same way to achieve substantially the same result as the invention claimed in claim 15

of the ’666 patent.

       Specifically, the court identified four ways in which the accused device functions

differently from the invention claimed in claim 15: the patent requires a pivotally-

mounted clamping member, whereas the accused device uses a slideably mounted

clamping member; the patent requires a rotational movement of the clamping member,

whereas the accused device uses a linear, sliding motion; the location of the center of

gravity of the clamping member is significant in the patented invention, whereas the

center of gravity does not influence the clamping force in the accused device; and the

patent describes two types of springs – a torsion and extension spring – that are

attached at one end to the cam and at the other end to a side wall, whereas the

accused device uses a compression spring that is not attached to any structure.

Opinion, 356 F. Supp. 2d at 320. The first three findings are not clearly erroneous, and

irrespective of the construction of the word “spring,” each of those findings provides an

independent basis for affirming the court’s finding that the accused device did not

infringe claim 15 under the doctrine of equivalents.




05-1319                                 10
                                      CONCLUSION

       We affirm the district court’s construction of the limitation “clamping means,” and

its finding of noninfringement in favor of Torvian.




05-1319                                  11
