NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________

INTELLIGENT AUTOMATION DESIGN, LLC,

Plaintiff-Appellant

v.

ZIMMER BIOMET CMF AND THORACIC, LLC, DBA

BIOMET MICROFIXATION,

Defendant-Appellee

______________________

2019-1100

______________________

Appeal from the United States District Court for the 

Middle District of Florida in No. 3:16-cv-01044-BJD-MCR, 

Judge Brian J. Davis.

______________________

Decided: January 30, 2020

______________________

JOHN DAVIS HOLMAN, Matthews, Lawson, McCutcheon 

& Joseph, PLLC, Houston, TX, argued for plaintiff-appellant. 

 KEVIN P. WAGNER, Faegre Baker Daniels LLP, Minneapolis, MN, argued for defendant-appellee. Also represented by LAUREN MARIE WILLIAMS STEINHAEUSER; DANIEL 

M. LECHLEITER, Indianapolis, IN. 

 ______________________

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Before PROST, Chief Judge, WALLACH and HUGHES, Circuit 

Judges.

HUGHES, Circuit Judge.

This is a patent case about controlling a motor used to 

drive a screwdriver bit. Intelligent Automation Design, 

LLC sued Zimmer Biomet CMF and Thoracic, LLC for infringement of all claims of U.S. Patent No. 7,091,683. The 

district court found that independent claims 1 and 6 were 

invalid as indefinite for failing to meet the requirements of 

35 U.S.C. § 112 ¶ 6.1 We agree with the district court that

§ 112 ¶ 6 applies because both claims include means-plusfunction terms. But because we conclude that the ’683 patent’s specification discloses sufficient structure to define 

the bounds of the means-plus-function terms, we reverse 

the district court’s finding of indefiniteness and remand for 

further proceedings.

I

The ’683 patent teaches both a method and a system

for controlling a motor used to turn a screwdriver bit.

Claim 1, the independent method claim, recites:

A method of controlling a motor (106) used to 

drive a screwdriver bit (105) such that screws 

(107) are seated to the optimum point of grip 

1 The America Invents Act (AIA) re-designated 

§ 112 ¶ 6 as § 112(f). Leahy-Smith America Invents Act, 

Pub. L. No. 112-29, sec. 4, 125 Stat. 284, 296 (2011). But 

the amended version of § 112 applies only to patent applications “filed on or after” September 16, 2012. See AIA 

§ 4(e), 125 Stat. at 297. Because the ’683 patent was filed 

before this date, we refer to the pre-AIA statute. See J.A. 

24.

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between the screw (107) and the work piece material, the method comprising:

(a) detecting a torque of the motor;

(b) determining a time when the torque 

reaches a maximum by an average means 

for determining an average value as a function of a current value and a new value,

thereby determining the optimum point of 

grip; and

(c) stopping the motor at the optimum 

point of grip.

’683 patent col. 4 ll.11–20 (emphasis removed).

Claim 6, the independent system claim, recites:

A speed/torque controller (100) for controlling the rotation speed and output 

torque of the motor (106) with either sensor 

feedback or back EMF used to monitor motor (106) speed and current used to monitor 

motor (106) torque, the controller comprising: 

a detector for detecting the output 

torque of the motor; and

a control circuit for determining a time 

when the torque reaches a maximum by an 

average means for determining an average 

value as a function of a current value and a 

new value, thereby determining the optimum point of grip, and stopping the motor 

at the optimum point of grip.

Id. col. 4 ll. 33–44 (emphasis removed).

The parties’ dispute centers on two issues: first,

whether “determining a time when the torque reaches a 

maximum” in claim 6 should be construed as a “meansCase: 19-1100 Document: 44 Page: 3 Filed: 01/30/2020
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plus-function” element subject to § 112 ¶ 6 and second, if 

the specification describes structure that adequately defines this function and thus, the invention. IAD appeals

from the district court’s entry of judgment holding independent claims 1 and 6 of the ’683 patent invalid as indefinite. We have jurisdiction under 28 U.S.C. § 1295(a)(1).

II

We review de novo the district court’s ultimate interpretation of a patent’s claims, including “means-plus-function” constructions in which the claim language invokes

§ 112 ¶ 6. Williamson v. Citrix Online, LLC, 792 F.3d 1339, 

1346, 1347 (Fed. Cir. 2015). We also review de novo a district court’s conclusion finding a claim indefinite under 

§ 112 ¶ 2. Cox Commc’ns, Inc. v. Sprint Commc’n Co. LP, 

838 F.3d 1224, 1228 (Fed. Cir. 2016). Biomet must prove 

any factual determination “critical to a holding on indefiniteness” by clear and convincing evidence. Id. For both 

claim construction and indefiniteness, we review de novo 

any underlying factual determinations based on evidence 

intrinsic to the patent, but review for clear error any underlying factual determinations based on extrinsic evidence. Williamson, 792 F.3d at 1346; Cox Commc’ns, Inc., 

838 F.3d at 1228. “To trigger clear error review, ‘it is not 

enough that the district court may have heard extrinsic evidence during a claim construction proceeding—rather, the 

district court must have actually made a factual finding . . . .’” Sonix Tech. Co. v. Publ’ns Int’l, Ltd., 844 F.3d 

1370, 1376 (Fed. Cir. 2017) (quoting Cardsoft, LLC v. VeriFone, Inc., 807 F.3d 1346, 1350 (Fed. Cir. 2015)). “If indefiniteness can be determined based solely on intrinsic 

evidence, our review is de novo.” Cox Commc’ns, Inc., 838 

F.3d at 1228. (citing Teva Pharms. USA, Inc. v. Sandoz, 

Inc., 574 U.S. 831, 841 (2015) (holding the same for claim 

construction)).

“An element in a claim for a combination may be expressed as a means . . . for performing a specified function” 

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but “such claim shall be construed to cover the corresponding structure” described in the specification. 35 U.S.C. 

§ 112 ¶ 6 (2000). “[T]he use of the word ‘means’ in a claim 

element creates a rebuttable presumption that § 112 [¶] 6 

applies[,]” but “the presence or absence of the word 

‘means’” may yield to the “essential inquiry” of whether an 

ordinarily skilled artisan would understand the recited 

claim element “to have a sufficiently definite meaning as 

the name for structure.” Williamson, 792 F.3d at 1348. In 

construing a means-plus-function element, the court identifies the claimed function, then determines “what structure, if any, disclosed in the specification corresponds to the 

claimed function.” Id. at 1351. “Under 35 U.S.C. § 112 ¶ 2 

and ¶ 6 . . . a means-plus-function clause is indefinite if a 

person of ordinary skill in the art would be unable to recognize the structure in the specification and associate it 

with the corresponding function in the claim.” Noah Sys., 

Inc. v. Intuit Inc., 675 F.3d 1302, 1312 (Fed. Cir. 2012).

III

A

We agree with the district court that § 112 ¶ 6 applies 

to claims 1 and 6. IAD does not contest the district court’s 

means-plus-function interpretation of claim 1. Since 

claim 1 recites the identical means-plus-function phrase as 

claim 6, including the “determining a time when torque 

reaches a maximum” function, that function should have 

the same meaning in claim 6.2 A “strong” principle of claim 

construction dictates that the same phrase in different 

2 Nor did IAD ask the district court to construe this 

phrase differently between claims 1 and 6. See J.A. 391–

94; J.A. 16–17. The district court considered whether the 

“control circuit” in claim 6 described sufficient structure for 

the disputed function, just as IAD requested. J.A. 18; J.A. 

392–94.

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claims of the same patent should have the same meaning 

unless “it is clear that the same phrase has different meanings in different claims.” In re Varma, 816 F.3d 1352, 1363 

(Fed. Cir. 2016). The recitation of a “control circuit for” 

performing the determining function in claim 6 provides 

detail about how the system achieves the function. But the 

recited “control circuit” does not change the meaning of “determining a time when torque reaches a maximum,” nor 

does it provide enough description of the structure to render the limitation structural, rather than functional. See

Power Integrations, Inc. v. Fairchild Semiconductor Int’l, 

Inc., 711 F.3d 1348, 1364–65 (Fed. Cir. 2013) (explaining 

how “not just any adjectival qualification or functional language” modifying a recited circuit will render a “circuit”

limitation structural, and providing examples of some adjectival qualifications that would do so). We thus affirm 

the district court’s application of § 112 ¶ 6 to “determining 

a time when torque reaches a maximum.” 

We next construe the claimed function. We agree with 

IAD’s interpretation. Despite arguing for a holistic claim 

interpretation, Biomet parses the claimed “determining a 

time” function too rigidly. Biomet’s interpretation of the 

function to mean determining when the torque is “arriving” 

at the maximum, see Appellee’s Br. 52, has a major flaw: 

both parties agree that function would be impossible to 

practice. Id. at 49–50; Appellant’s Reply Br. 16–17. “[A]

construction that renders the claimed invention inoperable 

should be viewed with extreme skepticism.” AIA Eng’g 

Ltd. v. Magotteaux Int’l S/A, 657 F.3d 1264, 1278 (Fed. Cir. 

2011).

An ordinarily skilled artisan could plausibly understand the claimed function to mean retrospectively observing changes in torque to ascertain when the torque has 

reached the maximum, the tense of “reaches” notwithstanding. Both the commonsense mathematics perspective 

that one cannot conclusively determine whether the torque 

reaches a maximum until one is able to calculate the slope 

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that follows the putative maximum, e.g., Appellee’s Br. 8, 

and the operability of the invention support this interpretation. The intrinsic record, if not entirely consistent,

yields stronger inferences in favor of this interpretation 

than against it. See, e.g., J.A. 455 (“[The claimed method]

stops the motor at the optimum point of grip between the 

screw and the material. It does [s]o by detecting a negative 

rate of change in torque that occurs right after the peak 

torque level is achieved at the maximum point of grip.” (emphasis added)); see also infra n.3. 

Because we understand Biomet to contest the sufficiency of the disclosed structure rather than the adequacy 

of the link between that structure and the claimed function, see Appellee’s Br. 54, we need not address the link between this claimed function and the structure in the 

specification.

B

We next address whether claims 1 and 6 are indefinite. 

“[F]or a claim element recited in means-plus-function format, ‘the specification must contain sufficient descriptive 

text by which a person of skill in the field of the invention 

would know and understand what structure corresponds to 

the means limitation.’” Bosch Auto. Serv. Sols., LLC v. 

Matal, 878 F.3d 1027, 1039 (Fed. Cir. 2017) (quoting Typhoon Touch Techs., Inc. v. Dell, Inc., 659 F.3d 1376, 

1383–84 (Fed. Cir. 2011)). When describing microprocessor-implemented functions, the specification must “disclose 

an algorithm for performing the claimed function” on the 

microprocessor “in any understandable terms including as 

a mathematical formula, in prose, or as a flow chart, or in 

any other manner that provides sufficient structure.” 

Noah Sys., 675 F.3d at 1312 (quoting Net MoneyIN, Inc. v. 

VeriSign, Inc., 545 F.3d 1359, 1367 (Fed. Cir. 2008) and

Finisar Corp. v. DirecTV Grp., Inc., 523 F.3d 1323, 1340 

(Fed. Cir. 2008)). Even so, “[t]his court does not impose a 

lofty standard in its indefiniteness cases.” In re Aoyama, 

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656 F.3d 1293, 1298 (Fed. Cir. 2011) (quoting Finisar, 

523 F.3d at 1341). Rather, the specification need only disclose enough to “permit one of ordinary skill in the art 

to . . . perceive the bounds of the invention.” Id. (quoting 

Finisar, 523 F.3d at 1340–41).

Here, the specification teaches “a series of instructions 

for the computer to follow,” Typhoon Touch, 659 F.3d at 

1384, that reasonably bounds how the claimed invention

might “determin[e] a time when torque reaches a maximum . . . thereby determining the optimum point of grip.” 

The microprocessor receives the already-filtered analog 

current signal representing torque and smooths it using an 

averaging formula. See ’683 patent col. 3 ll. 9–26. The microprocessor measures and monitors the value of the signal 

after it receives and smooths it. See id. Then, if the microprocessor detects a decrease in current, signifying that the 

torque has begun dropping and therefore that the screw 

has reached the optimum point of grip, it signals the controller to stop the motor. Id. at col. 3 ll. 26–28. Understood 

as a whole, this written description provides a coherent series of steps defining how to perform the corresponding 

claimed steps: detecting the motor torque, smoothing that 

torque using an average means (the averaging formula), 

and stopping the motor at the optimum point of grip, determined by the time the torque reaches a maximum.3 Id. at

col. 4 ll. 15–20.

3 The parallels between the written description and our 

interpretation of the claimed function reinforce the correctness of our interpretation. See Budde v. Harley-Davidson, 

Inc., 250 F.3d 1369, 1379–80 (Fed. Cir. 2001) (“In construing [means-plus-function] terms used in patent claims, it is 

necessary to consider the specification as a whole, and to 

read all portions of the written description, if possible, in a 

manner that renders the patent internally consistent.”).

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Because the disclosed algorithm and the claimed function both solve the problem of establishing the “optimum 

point of grip” when the microprocessor should signal the 

control circuit to cut power to the motor, an ordinarily 

skilled artisan would associate the algorithm and the function. Given other simplifying assumptions disclosed by the 

patent, an ordinarily skilled artisan could perceive the 

bounds of the invention. For instance, the ’683 patent

teaches that the preferred embodiment’s torque controller 

is designed to measure the value of a torque profile that is 

continuously increasing to a single peak before it drops. 

See ’683 patent fig.5; id. col. 2 ll. 43–64, col. 3 ll. 3–5. The 

smoothing mechanisms taught by the ’683 patent also help 

ensure that the torque curve takes this shape. See id. col. 3 

ll. 29–46. Given these assumptions—whether realistic or 

not—the ’683 patent need only describe a simple computational process to define how to determine the time that the 

torque reaches a maximum. It does so: The microprocessor 

should “monitor” the motor current; when it detects a decrease in current, torque has reached a maximum and the 

microprocessor should signal the controller to stop the motor. We are persuaded that an ordinarily skilled artisan 

would find this a reasonably certain description of how the 

invention determines a time when the torque reaches a 

maximum, especially in view of the ultimate goal of determining when to stop the screwdriver.

Biomet does not persuade us otherwise, particularly 

given its burden to show clear and convincing evidence of 

indefiniteness. In addition to relying on a faulty interpretation of the claimed function, Biomet mistakenly fixates

on the ’683 patent’s inability to solve certain technical 

problems that the patent does not profess to solve. Biomet 

further misplaces its focus in making an immaterial comparison between the ’683 patent’s “algorithm” and the algorithm applied in IAD’s commercial embodiment (because 

the latter purportedly would solve the alleged technical 

problems). These arguments rest on an implicit critique of 

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the ’683 patent perhaps relevant to other patentability criteria, but not persuasive when evaluating indefiniteness. 

Cf. Miles Labs., Inc. v. Shandon Inc., 997 F.2d 870, 875 

(Fed. Cir. 1993) (“The invention’s operability may say nothing about a skilled artisan’s understanding of the bounds 

of the claim.”); EON Corp. IP Holdings LLC v. AT & T Mobility LLC, 785 F.3d 616, 624 (Fed. Cir. 2015) (explaining 

the indefiniteness “question” as “whether the specification 

contains a sufficiently precise description of the ‘corresponding structure’ to satisfy section 112, paragraph 6, not 

whether a person of skill in the art could devise some 

means to carry out the recited function”). 

Nor does Biomet’s expert testimony alter this conclusion. Even if we consider the district court’s references to 

this testimony to be findings of fact, when the specification

“unambiguously set[s] forth” the meaning of a claim term,

expert testimony about the claim term becomes “irrelevant 

to the issue of indefiniteness.” Personalized Media 

Commc’ns, LLC v. Int’l Trade Comm’n, 161 F.3d 696, 706

(Fed. Cir. 1998); see id. at 705–706 (explaining how the 

specification sufficiently informed an ordinarily skilled artisan of the meaning of a claim term and thus rejecting expert testimony that the specification’s disclosure was 

inadequate). Applying IAD’s sounder interpretation of the 

claimed function, the specification manifestly discloses an

“algorithm” to perform that claimed function. Although 

the specification cannot itself unambiguously establish 

that the algorithm adequately defines the structure of the 

claimed function, Biomet’s expert testimony does not provide clear and convincing evidence of the algorithm’s insufficiency.4 To the extent that this testimony even discusses 

4 The district court indisputably did not make findings 

of fact from Biomet’s expert testimony regarding the sufficiency of the algorithm. The district court characterized 

the expert testimony as showing that the specification did 

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the sufficiency of the specification’s disclosed algorithm, 

the testimony, like Biomet’s arguments, focuses on the

“sufficiency of the written description to enable the practice 

of the invention of the claims” and not the “imprecision of 

the claims.” Personalized Media Commc’ns, LLC, 161 F.3d 

at 706.

We would not hold out the ’683 patent as an exemplar

of impeccable patent drafting. But given the simple problem described by this patent, the brief passage taught in 

the specification suffices to define the bounds of the 

claimed solution. In claims 1 and 6, the invention determines a time that torque reaches a maximum by using a 

microprocessor to detect a decrease in torque. A “decrease 

in current, corresponding to a drop in torque” provides a 

clear, reasonably certain boundary, particularly in light of 

the specification’s explanation of the assumptions inherent 

in the method. That is enough for definiteness.

IV

We have considered the parties’ remaining arguments 

and find them unpersuasive. We agree with the district

court that the disputed claim term is subject to a meansplus-function analysis. But we reverse the district court’s 

judgment holding the ’683 patent invalid for indefiniteness 

and remand for further proceedings consistent with this 

opinion.

not disclose an algorithm, see J.A. 22, therefore foreclosing 

the possibility of fact-findings about the sufficiency of an 

algorithm. Evidence not relied on by the district court does 

not receive deferential review on appeal. Cf. CardSoft, 

807 F.3d at 1351 n.1 (“[T]he mere submission of extrinsic 

evidence is not enough to mandate deference to a district 

court’s claim construction.”).

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AFFIRMED-IN-PART, REVERSED-IN-PART, 

AND REMANDED

No costs.

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