Grace Instrument Industries, LLC v. Chandler Instruments Company, LLC, Ametek, Inc.

United States Court of Appeals
for the Federal Circuit
______________________
GRACE INSTRUMENT INDUSTRIES, LLC,
Plaintiff-Appellant
v.
CHANDLER INSTRUMENTS COMPANY, LLC,
AMETEK, INC.,
Defendants-Appellees
______________________
2021-2370
______________________
Appeal from the United States District Court for the
Southern District of Texas in No. 4:20-cv-01749, Judge An-
drew S. Hanen.
______________________
Decided: January 12, 2023
______________________
BRADFORD T URNER L ANEY , Raley & Bowick, LLP, Hou-
ston, TX, argued for plaintiff-appellant. Also represented
by ROBERT MCG EE B OWICK, J R.
J ULIE S. G OLDEMBERG, Morgan, Lewis & Bockius LLP,
Philadelphia, PA, argued for defendants-appellees. Also
represented by EUGENE HWANGBO, J ASON C. WHITE, Chi-
cago, IL; ARCHIS VASANT O ZARKAR , WILLIAM R. P ETERSON,
MELISSA MARIE STORY , Houston, TX.
______________________
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Before CHEN, CUNNINGHAM , and STARK, Circuit Judges.
CHEN, Circuit Judge.
Grace Instrument Industries, LLC (Grace) appeals a
claim construction order issued by the United States Dis-
trict Court for the Southern District of Texas finding the
term “enlarged chamber” indefinite and construing the
term “means for driving said rotor to rotate located in at
least one bottom section.” As a result of the district court’s
order, the parties stipulated that asserted claims 1, 2, 4, 5,
7–9, 11, 14, 15, and 17 of U.S. Patent No. 7,412,877
(’877 patent) are invalid and that claims 4, 5, 7–9, 11, 14,
15, and 17 are not infringed, and the court entered final
judgment in favor of Chandler Instruments Company, LLC
(Chandler). Because the district court erred in its analysis
of the term “enlarged chamber,” we vacate the district
court’s determination that “enlarged chamber” is indefinite
and remand for further proceedings consistent with this
opinion. We affirm the district court’s construction of
“means for driving said rotor to rotate located in at least
one bottom section.”
BACKGROUND
I
When drilling oil wells, drilling fluid is used to drive a
drill bit and bring drill cuttings back to the surface of the
well. ’877 patent col. 1 ll. 17–19. The drilling fluid’s vis-
cosity is critical to the well’s operation—too high and the
fluid is too hard to pump; too low and the fluid cannot carry
the drill cuttings back to the surface. Id. at col. 1 ll. 19–24.
Thus, before use, drilling fluid viscosity is first measured
using a viscometer that simulates “down-hole” conditions—
i.e., the temperature and pressure at the drill bit while
drilling. Id. at col. 1 ll. 26–28.
In a liquid pressurized viscometer, pressurization fluid
is added to pressurize the sample drilling fluid within the
viscometer to down-hole conditions while the sample fluid
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is stirred by a rotor to measure its viscosity. The introduc-
tion of the pressurization fluid compresses the sample drill-
ing fluid, causing it to take up less volume within the
viscometer. Ideally, the pressurization fluid does not mix
with the sample fluid being measured to ensure that the
viscometer reports the viscosity of only the sample fluid
and not the viscosity of a mixture of the two fluids. Id. at
col. 1 ll. 53–56, col 5 ll. 55–57, col. 5 ll. 59–62, col. 12
ll. 21–23.
Before the ’877 patent, liquid pressurized viscometers
separated the sample fluid from the pressurization fluid in
one of two ways. Some viscometers relied on the density
difference between the fluids, but if some pressurization
fluid entered the chamber where the sample fluid was be-
ing tested, stirring by the rotor would cause the two fluids
to mix, leading to measurement errors. Id. at col. 1
ll. 53–56, col. 5 ll. 59–62. Other viscometers used a seal to
separate the two fluids, but friction caused by the sample
fluid rubbing against the seal as the sample fluid was
stirred led to inaccurate results. Id. at col. 1 ll. 43–46, col. 5
ll. 57–59.
The ’877 patent’s viscometer purportedly eliminates
measurement errors caused by seal friction or commingling
of sample and pressurization fluids by offering a different
solution. Id. at col. 2 ll. 1–3, col. 12 ll. 21–23. Instead of
using a seal to separate the fluids, the ’877 patent’s viscom-
eter includes an “enlarged” chamber located between a
lower chamber, housing the sample fluid, and a pressuri-
zation fluid inlet, located in the top section of the viscome-
ter’s pressure vessel. This enlarged chamber is large
enough such that the level of the sample fluid, which before
pressurization initially fills both the lower chamber and
the enlarged chamber, never falls below the transition
point between the lower chamber and enlarged chamber
when the application of the pressurization fluid compresses
the sample fluid. By keeping the sample fluid level above
the top of the lower chamber and within the enlarged
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chamber, even when the sample fluid is compressed, the
claimed viscometer design ensures that any mixing be-
tween the two fluids occurs within the enlarged chamber
and no pressurization fluid enters the lower chamber
where the sample fluid is being tested. Id. at col. 5 l. 55 –
col. 6 l. 6; see also id. at col. 8 ll. 37–48, col. 10 ll. 49–60.
Thus, the ’877 patent’s design is intended to “[t]otally elim-
inate the measurement error because of sample mixing
with pressurization fluid in a comparative viscometer.” Id.
at col. 12 ll. 21–23.
The ’877 patent discloses three embodiments of its vis-
cometer. The first embodiment is shown below.
Id. FIG. 1 (exploding out chambers 45 and 49); see also id.
FIG. 2, FIG. 3. In each embodiment, chambers 45 and 49
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act together to contain the pressurization fluid as the sam-
ple fluid in a “lower measurement zone” is compressed:
[W]hen pressurization fluid is applied, the sample
fluid level is pushed down due to the compressibil-
ity of tested sample. Thus initial sample fluid in-
side of chamber 45 goes down to chamber 49
through small gap 25, and some of the initial sam-
ple fluid inside of chamber 49 goes down to the
lower measurement zone through small gap 27.
However, chamber 45 and chamber 49 are large
enough so that at maximum rated pressure, cham-
ber 49 is still at least half filled with sample fluid.
This ensures the accuracy of the measurement be-
cause measurement zone below anti mixer bottom
fin 82 is always totally filled with sample fluid.
Id. at col. 5 l. 63 – col. 6 l. 6; see also id. at col. 8 ll. 37–48,
col. 10 ll. 49–60. Although the three embodiments use both
chamber 45 and chamber 49, the ’877 patent also explains
that “[i]t is not necessary to have both chamber 45 and
chamber 49.” Id. at col. 10 ll. 64–65. “With just cham-
ber 45 or chamber 49 and sufficient volume, pressuriza-
tion fluid and test sample can still be separated well.” Id.
at col. 10 ll. 65–67 (emphasis added).
To measure the viscosity of the sample fluid in the
lower measurement zone, the ’877 patent discloses a rotor
that is driven by magnetic coupling but also “could be
driven to rotate with any means such as directly driven at
the bottom of the cell body with dynamic seal, etc.” Id. at
col. 2 ll. 11–13, col. 4 ll. 54–59, col. 5 ll. 42–54, col. 7
ll. 41–47, col. 8 ll. 24–36, col. 9 ll. 61–67, col. 10 ll. 36–48,
col. 11 ll. 41–43.
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Claims 1 and 4 are independent claims that claim a
pressurized device and a viscometer, respectively:
1. A pressurized device comprising:
(a) a pressure vessel within which is verti-
cally disposed at least one top section filled
with a pressurization fluid of a first density
and at least one lower section filled with a
test sample of a second density,
(b) an enlarged chamber with reduced
openings positioned between the at least
one top section and the at least one bottom
section for communicating pressure with
said top section and said lower section
within said pressure vessel,
(c) whereby said pressurization fluid would
not mix with said test sample because of
the nature of their density difference.
4. Viscometer comprising:
(a) a pressure vessel within which at least
one top section filled with a pressurization
fluid of a first density,
(b) within said pressure vessel a rotor
which is driven to rotate while contacting
with a sample liquid of a second density to
be measured,
(c) means for driving said rotor to rotate lo-
cated in at least one bottom section,
(d) a bob within said rotor,
(e) an enlarged chamber with reduced
openings positioned between the at least
one top section and the at least one bottom
section for communicating pressure located
above said bob,
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(f) whereby said pressurization fluid would
not mix with said sample liquid because of
the nature of their density difference.
Id. at col. 12 ll. 34–47, col. 12 ll. 52–67 (emphases added).
The two italicized claim terms are the focus of this appeal.
II
On May 19, 2020, Grace sued Chandler in the United
States District Court for the Southern District of Texas, al-
leging that Chandler’s Model 7600 viscometer infringed
multiple claims of the ’877 patent. J.A. 52; J.A. 61–65. On
July 1, 2021, the district court issued its claim construction
order. Grace Instrument Indus., LLC v. Chandler Instru-
ments Co., No. 4:20-cv-1749, 2021 WL 2711987 (S.D. Tex.
July 1, 2021) (Claim Construction Order).
Relevant here, the district court held that the term “en-
larged chamber” in claims 1 and 4 is indefinite. Id. at *4–5.
The district court explained that “enlarged” is a “term of
degree” that “necessarily calls for some comparison against
some baseline.” Id. at *5 (quoting Liberty Ammunition,
Inc. v. United States, 835 F.3d 1388, 1395 (Fed. Cir. 2016)).
Finding that the ’877 patent “does not provide the requisite
objective boundaries” for a skilled artisan, the district court
held that “enlarged chamber” is indefinite. Id. at *5. The
district court rejected Grace’s argument that “enlarged
chamber” could be defined by its purpose, finding that “ex-
plaining that something is large enough to do a certain task
does not answer the question: larger than what?” Id. The
district court further disagreed with Grace that the base-
line for “enlarged” is the prior art, explaining that “this is
not evident from the ’877 Patent itself.” Id.
The district court also construed “means for driving
said rotor to rotate located in at least one bottom section.”
Id. at *7–8. The parties agreed that the term was subject
to 35 U.S.C. § 112, ¶ 6 (pre-AIA), and the table below illus-
trates the parties’ positions on the construction:
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Id. at *7; J.A. 34. The parties thus agreed that the function
is “driving said rotor to rotate,” but they disputed the
means and whether the phrase “located in at least one bot-
tom section” modifies “rotor,” as Grace contended, or
“means for driving,” as Chandler argued. Claim Construc-
tion Order, 2021 WL 2711987, at *7.
To resolve the dispute, the district court looked to
claim 14, which depends from claim 4 and recites:
14. The viscometer of claim 4 wherein said means
for driving said rotor to rotate is a magnetic cou-
pling across said pressure vessel wall.
’877 patent col. 13 ll. 22–24. The district court found that
Grace’s proposed construction of the means (1) was “not
broad enough to include magnetic coupling” as it must be-
cause of dependent claim 14 and (2) would exclude other
terms described in the patent as causing the rotor to rotate.
Claim Construction Order, 2021 WL 2711987, at *7 (citing
’877 patent col. 5 ll. 45–47 (magnet mount), col. 4 ll. 55–59
(gear box, motor, driving magnet, or coupling magnet),
col. 12 ll. 41–43 (direct drive at bottom of the cell body)).
Thus, the district court adopted Chandler’s proposed con-
struction of the means.
The district court also agreed with Chandler that “lo-
cated in at least one bottom section” modifies “means for
driving,” not “rotor.” Id. at *8. The district court explained
that this interpretation “conform[s] with [the] usual rules
of grammar and sentence structure” and is confirmed by
limitation 4(b), which already describes the rotor’s location
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as “within said pressure vessel,” not necessarily in the “bot-
tom section.” Id.
Thus, the district court adopted in its entirety Chan-
dler’s proposed construction of “means for driving said ro-
tor to rotate located in at least one bottom section.” Id.
Accordingly, the function of the “means for driving” limita-
tion is “driving said rotor to rotate, where the means for
driving is located in at least one bottom section,” and the
corresponding structure is “(i) magnetic coupling (magnetic
mount, gear box or motor, driving magnet, coupling mag-
net), or (ii) direct drive at bottom of cell body, and known
equivalents.” Id. at *7–8.
The parties then stipulated that claims 1, 2, 4, 5, 7–9,
11, 14, 15, and 17 are invalid based on the district court’s
determination that “enlarged chamber” is indefinite, and
that claims 4, 5, 7–9, 11, 14, 15, and 17 are not infringed
based on the district court’s construction of “means for driv-
ing said rotor to rotate in at least one bottom section.”
J.A. 1529–34. The district court entered a final judgment
on September 23, 2021. J.A. 19–20.
Grace timely appealed. We have jurisdiction under 28
U.S.C. §§ 1291 and 1295(a)(1).
D ISCUSSION
Claim construction requires determining how a skilled
artisan would understand a claim term “in the context of
the entire patent, including the specification.” Phillips v.
AWH Corp., 415 F.3d 1303, 1313 (Fed. Cir. 2005) (en banc).
We begin by considering the language of the claims them-
selves. Id. at 1314. However, “claims must be read in view
of the specification, of which they are a part.” Id. at 1315
(internal quotation marks omitted) (quoting Markman v.
Westview Instruments, Inc., 52 F.3d 967, 978 (Fed. Cir.
1995) (en banc)). We have explained that the specification
is the “single best guide to the meaning of a disputed term,”
Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582
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(Fed. Cir. 1996), and “is, thus, the primary basis for con-
struing the claims,” Phillips, 415 F.3d at 1315 (citation and
internal quotation marks omitted). A court also should
consider the patent’s prosecution history, and may rely on
dictionary definitions, “so long as the dictionary definition
does not contradict any definition found in or ascertained
by a reading of the patent documents.” Id. at 1317,
1322–23 (citation and internal quotation marks omitted).
We review claim construction based on intrinsic evi-
dence de novo and review any findings of fact regarding ex-
trinsic evidence for clear error. SpeedTrack, Inc. v.
Amazon.com, Inc., 998 F.3d 1373, 1378 (Fed. Cir. 2021) (cit-
ing Teva Pharms. USA, Inc. v. Sandoz, Inc., 574 U.S. 318,
331–32 (2015)). Intrinsic evidence includes the patent’s
claims, specification, and prosecution history. Cont’l Cirs.
LLC v. Intel Corp., 915 F.3d 788, 795 (Fed. Cir. 2019). Ex-
trinsic evidence is “secondary to the intrinsic evidence” and
“consists of all evidence external to the patent and prose-
cution history, including expert and inventor testimony,
dictionaries, and learned treatises.” Id. at 799 (quoting
Phillips, 415 F.3d at 1317). “If the meaning of a claim term
is clear from the intrinsic evidence, there is no reason to
resort to extrinsic evidence.” Seabed Geosolutions (US) Inc.
v. Magseis FF LLC, 8 F.4th 1285, 1287 (Fed. Cir. 2021).
A “patent is invalid for indefiniteness if its claims, read
in light of the specification delineating the patent, and the
prosecution history, fail to inform, with reasonable cer-
tainty, those skilled in the art about the scope of the inven-
tion.” Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S.
898, 901 (2014). “The ultimate conclusion that a claim is
indefinite under 35 U.S.C. § 112, ¶ 2 is a legal conclusion,
which we review de novo.” Cox Commc’ns, Inc. v. Sprint
Commc’n Co., 838 F.3d 1224, 1228 (Fed. Cir. 2016) (citation
omitted). “As in claim construction, we review a district
court’s underlying factual determinations for clear error.”
Id. (citations omitted). Moreover, “[a]ny fact critical to a
holding on indefiniteness . . . must be proven by the
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challenger by clear and convincing evidence.” Id. (altera-
tion in original) (citation and internal quotation marks
omitted).
I. Enlarged Chamber
Grace argued before the district court that the term
“enlarged chamber” should be construed as “the area be-
tween reduced openings that is large enough to hold excess
test sample (i.e., the type of fluid normally used in these
machines) to prevent mixing of pressurization fluid and
test sample below the bottom fin during elevated pressuri-
zation.” Claim Construction Order, 2021 WL 2711987,
at *5. The district court declined to adopt that construc-
tion, concluding that the ’877 patent fails to disclose objec-
tive boundaries for a skilled artisan to know what the
claimed “enlarged chamber” must be larger than. Id. This
was error. The intrinsic record informs a skilled artisan
that the ’877 patent and its claims are directed to a viscom-
eter with an “enlarged chamber” that is large enough to
prevent pressurization fluid from entering the lower sec-
tion of the pressure vessel—where the viscosity of the test
sample is being measured—during elevated pressuriza-
tion. In other words, the enlarged chamber has to be able
to contain enough sample fluid at the pre-pressurization
stage such that, during pressurization, the sample fluid
level does not fall below the bottom of the enlarged cham-
ber and into the viscometer’s lower, testing section. This
design ensures that any mixing of the pressurization fluid
and compressed sample fluid occurs within the enlarged
chamber and not in the lower, testing section. Thus, in the
context of this patent, “enlarged chamber” does not require
that chamber to be larger than some baseline object; rather
it must be large enough to accomplish a particular function.
The ’877 patent’s specification guides us to the term’s
meaning. The specification explains that “[o]ne of the
drawbacks of most liquid pressurized viscometers is the
mixing between tested sample and pressurization fluid,”
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which leads to inaccurate test results. ’877 patent col. 5
ll. 55–57, col. 5 ll. 59–62; see also id. at col. 1 ll. 53–56. Ac-
cording to the patent, prior art viscometers attempted to
remedy this inaccuracy by using a seal between the pres-
surization fluid and sample fluid, but the seal “induce[s]
friction error causing inaccurate measurement.” Id. at
col. 5 ll. 57–59; see also id. at col. 1 ll. 43–46; discussion su-
pra Background § I. The ’877 patent explains that the “cur-
rent invention” solves this problem through use of
chambers 45 and 49: “[C]hamber 45 and chamber 49 are
large enough so that at maximum rated pressure, chamber
49 is still at least half filled with sample fluid. This ensures
the accuracy of the measurement because measurement zone
below anti mixer bottom fin 82 is always totally filled with
sample fluid.” ’877 patent col. 6 ll. 2–6 (emphases added).
The patent discloses the same for two other embodiments,
id. at col. 8 ll. 43–48, col. 10 ll. 55–60, and explains that a
single chamber could be used instead of two chambers (i.e.,
chamber 45 and chamber 49), provided the single chamber
has “sufficient volume,” id. at col. 10 ll. 64–67. Finally, the
specification explains that “[b]y providing an enlarged
chamber such as chamber 45 or chamber 49 . . . this config-
uration can be applied to other applications than viscome-
ters to reduc[e] the mixing of test sample and
pressurization fluid.” Id. at col. 11 ll. 28–32 (emphasis
added). A skilled artisan would understand from these dis-
closures that the “enlarged chamber” comprises cham-
bers 45 and/or 49 and is large enough to prevent the
pressurization fluid from mixing with the sample fluid in
the lower measurement zone during elevated pressuriza-
tion, thus avoiding measurement errors caused by commin-
gling of the sample and pressurization fluids in prior-art
viscometers.
The prosecution history supports this understanding.
In response to a rejection over U.S. Patent No. 4,633,708
(Blommaert), which taught use of a seal, the applicant ex-
plained “[b]y having ‘an enlarged chamber with reduced
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openings for communicating pressure’, pressurization oil
will not contaminate [the] test sample even without a seal
as described in Blommaert.” J.A. 1063; see also
J.A. 1066–67, 1069–70. The applicant also explained that
the “[c]urrent invention solved a long lasting problem” in
high-pressure testing of drilling fluids, including “the large
measurement error . . . induced due to the friction of the
seal” in designs like Blommaert. J.A. 1062–63; see also
J.A. 1064, 1066, 1068, 1070. The examiner subsequently
allowed the claims. A skilled artisan would understand
from the prosecution history that the purpose and role of
the ’877 patent’s “enlarged chamber” is to prevent commin-
gling of the sample and pressurization fluids in the lower
measurement zone without using a seal, thereby avoiding
the measurement errors seen in prior-art viscometers like
Blommaert.
Thus, although “enlarged chamber” is not a term of art,
the intrinsic record sufficiently guides a skilled artisan to
the meaning of that term as used in the ’877 patent. The
district court erred in its reliance on extrinsic evidence—
i.e., dictionary definitions—that contradict the scope and
meaning of “enlarged chamber” that a skilled artisan
would ascertain by reading the intrinsic record. See Phil-
lips, 415 F.3d at 1322–23; see also id. at 1316 (“[O]ur cases
recognize that the specification may reveal a special defini-
tion given to a claim term by the patentee that differs from
the meaning it would otherwise possess.”); Trs. of Colum-
bia Univ. v. Symantec Corp., 811 F.3d 1359, 1363 (Fed. Cir.
2016) (“The only meaning that matters in claim construc-
tion is the meaning in the context of the patent.”). Where
the specification instructs as to the meaning of a claim
term, “the inventor’s lexicography governs.” Phillips, 415
F.3d at 1316.
Chandler, for its part, is correct that the ’877 patent’s
specification refers to “enlarged chamber” only twice, but,
for the reasons already stated, a skilled artisan would un-
derstand that the specification’s descriptions of an
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enlarged chamber and the corresponding embodiments ad-
equately guide the skilled artisan to the meaning of “en-
larged chamber.” Further, to the extent Chandler would
require an explicit definition of the term “enlarged cham-
ber,” that is incorrect. As our en banc opinion in Phillips
explained, a “claim term may be clearly redefined without
an explicit statement of redefinition,” and “[e]ven when
guidance is not provided in explicit definitional format, the
specification may define claim terms by implication such
that the meaning may be found in or ascertained by a read-
ing of the patent documents.” 415 F.3d at 1320–21 (first
quoting Bell Atl. Network Servs., Inc. v. Covad Commc’ns
Grp., Inc., 262 F.3d 1258, 1268 (Fed. Cir. 2001); and then
quoting Irdeto Access, Inc. v. Echostar Satellite Corp., 383
F.3d 1295, 1300 (Fed. Cir. 2004)); see also Aventis Pharma
S.A. v. Hospira, Inc., 675 F.3d 1324, 1330 (Fed. Cir. 2012)
(“This clear expression need not be in haec verba but may
be inferred from clear limiting descriptions of the invention
in the specification or prosecution history.”).
The district court’s reliance on dictionary definitions of
“enlarged” rather than the meaning a skilled artisan would
reasonably understand from the intrinsic record led, in
part, to its reliance on Liberty Ammunition. There, we
found that “reduced area of contact” must be compared to
the prior-art ammunition because there was no other ob-
jective boundary for a skilled artisan. Liberty Ammunition,
835 F.3d at 1396–97 (citing Interval Licensing LLC v. AOL,
Inc., 766 F.3d 1364, 1370–71 (Fed. Cir. 2014)). Here, how-
ever, the intrinsic record provides an objective boundary
for a skilled artisan—i.e., the “enlarged chamber” must be
large enough to prevent, during elevated pressurization,
commingling of sample and pressurization fluids in the
lower measurement zone. Unlike Liberty Ammunition,
this objective boundary does not require a comparison to
the size of prior-art chambers.
Our decision in Biosig Instruments, Inc. v. Nautilus,
Inc., 783 F.3d 1374 (Fed. Cir. 2015), is more applicable.
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There, we reviewed claims directed to a heart rate monitor
with a “spaced relationship” between a first live electrode
and a first common electrode. Id. at 1376. We explained
that, although the patent “does not specifically define
‘spaced relationship’ with actual parameters,” the intrinsic
evidence demonstrated that a “skilled artisan would be
able to determine this language requires the spaced rela-
tionship to be neither infinitesimally small nor greater
than the user’s hands”:
For example, on the one hand, the distance be-
tween the live electrode and the common electrode
cannot be greater than the width of a user’s hands
because claim 1 requires the live and common elec-
trodes to independently detect electrical signals at
two distinct points of a hand. On the other hand,
it is not feasible that the distance between the live
and common electrodes be infinitesimally small, ef-
fectively merging the live and common electrodes
into a single electrode with one detection point.
Id. at 1382–83 (quoting Biosig Instruments, Inc. v. Nauti-
lus, Inc., 715 F.3d 891, 899 (Fed. Cir. 2013), vacated sub
nom. Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S.
898 (2014)). Thus, we found that “a skilled artisan would
understand the inherent parameters of the invention as
provided in the intrinsic evidence.” Id. at 1384. The same
is true here. A skilled artisan would understand the inher-
ent parameters of the “enlarged chamber” through the in-
trinsic evidence. Like the spaced relationship in Nautilus,
the “enlarged chamber” must be a certain minimum size,
or large enough, to maintain sample fluid within the en-
larged chamber when the sample fluid is under elevated
pressurization.
Although we disagree with the district court’s conclu-
sion that “enlarged chamber” must be larger than some-
thing else rather than large enough to achieve a particular
purpose, it appears that the indefiniteness question is not
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yet fully resolved and may require further fact finding on
remand. Chandler, for example, argues that the term “en-
larged chamber” is still indefinite because the claims recite
an additional limitation that relies on the “density differ-
ence” between the fluids—not the enlarged chamber—to
prevent mixing. Appellee’s Br. 20–22, 32–33. Chandler
also argues that different sample fluids will compress in
different amounts under the same pressure, and thus a
skilled artisan cannot determine if a given viscometer’s
chamber satisfies the “enlarged chamber” limitation due to
the variance in how much different sample fluids compress.
Appellee’s Br. 23–25, 32–33; see also Appellee’s Letter,
Aug. 8, 2022, ECF No. 50. Grace disagrees with the merits
of both arguments and asserts that both arguments are
waived because they were not raised before the district
court. Appellant’s Reply Br. 4–7, 15–19; Appellant’s Let-
ter, Aug. 11, 2022, ECF No. 53. Grace also makes addi-
tional arguments based on the extrinsic record.
Appellant’s Br. 45–54. We will not address these argu-
ments in the first instance. It is appropriate for the district
court to consider these types of arguments on remand, in-
cluding whether any have been waived. We also note that
the district court made no finding as to the identity of the
pertinent person of ordinary skill in the art, from whose
perspective the “reasonable certainty” analysis must be un-
dertaken. This oversight may well be due to the parties’
relative inattention to this factual issue, although the res-
olution of it may also be informative as to whether, on re-
mand, the claims are again determined to be indefinite.
See generally Nautilus, 572 U.S. at 901.
In sum, we find the term “enlarged chamber” in the
’877 patent to mean “a chamber that is large enough to con-
tain excess test sample prior to pressurization to prevent
mixing of the test sample and pressurization fluid in the
lower measurement zone when the test sample is pressur-
ized to maximum rated pressure.” We thus vacate the dis-
trict court’s determination that “enlarged chamber” is
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indefinite, vacate the district court’s invalidity determina-
tions based thereon, and remand for further proceedings
consistent with this opinion.
II. Means for Driving Said Rotor to Rotate Located in
at Least One Bottom Section
Grace also contests the district court’s construction of
“means for driving said rotor to rotate located in at least
one bottom section.” Grace argues that the court erred in
finding that the term “bottom section” refers to the bottom
section of the viscometer rather than the bottom section of
the pressure vessel and in finding that “located in at least
one bottom section” modifies “means for driving” rather
than “rotor.” Appellant’s Br. 57–68, 70–71. According to
Grace, the correct construction of “means for driving” in-
cludes a “magnet holder” and a “direct drive” that attaches
to the bottom section of the rotor rather than “at bottom of
cell body.” Appellant’s Br. 67–69. We disagree and thus
affirm the district court’s construction.
A. The District Court’s Construction
We first consider whether the phrase “located in at
least one bottom section” in limitation 4(c) modifies “means
for driving” or “rotor.” Starting with the claim language,
we agree with the district court that the most natural read-
ing of limitation 4(c) requires the phrase “located in at least
one bottom section” to modify “means for driving” and not
“rotor.” In this limitation, “means” is a noun modified by
the prepositional phrase “for driving said rotor to rotate.”
The noun “means” also is modified by the participle phrase
“located in at least one bottom section.” Because the prep-
ositional phrase is unnecessary, the sentence is best read
as a “means” that is “located in at least one bottom section.”
Had the patentee intended for “located in at least one bot-
tom section” to modify “rotor,” the patentee would have
placed the “located in at least one bottom section” phrase
before “to rotate.”
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That “means for driving said rotor to rotate” should be
read as a unit, composed of a noun modified by a preposi-
tional phrase, is confirmed by dependent claim 14.
Claim 14 recites the viscometer of claim 4 “where said
means for driving said rotor to rotate is . . . .” ’877 patent
col. 13 ll. 23–24 (emphasis added). Thus, in claim 14, the
same noun modified by the same prepositional phrase is
used in the same manner as in claim 4, indicating that the
patentee intended the noun and prepositional phrase to be
read together. Thus, “located in at least one bottom sec-
tion” modifies the entire “means” unit and not the “rotor.”
Comparing limitations 4(b) and 4(c) supports this in-
terpretation. Limitation 4(b) introduces the “rotor” and ex-
plains that the rotor is located “within said pressure
vessel.” Id. at col. 12 ll. 55–57. Limitation 4(c) introduces
the “means for driving” and explains that the “means for
driving” is “located in at least one bottom section.” Id. at
col. 12 ll. 58–59. A skilled artisan reading claim 4 would
understand that these limitations are directed to different
components of the viscometer and also describe the corre-
sponding locations for those components. Indeed, it would
make little sense for limitation 4(b) to introduce the rotor,
explain that it is located in the pressure vessel, and then,
in a separate limitation directed to the “means for driving,”
explain that the rotor is located in the bottom section.
Next, we agree with the district court that the intrinsic
record requires that the claimed “bottom section” refers to
the bottom section of claim 4’s viscometer, not the pressure
vessel component of the viscometer. Dependent claim 14
explains that the “means for driving” is a “magnetic cou-
pling across said pressure vessel wall.” Id. at col. 13
ll. 23–25 (emphasis added). The “means for driving” thus
cannot be in the bottom section of the pressure vessel be-
cause claim 14 requires the “means for driving” to operate
across the pressure vessel wall—i.e., magnetic coupling
components must be located inside and outside the pres-
sure vessel. Thus, the “means for driving” must be in the
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“bottom section” of the overall viscometer rather than the
pressure vessel because that understanding encompasses
the “means for driving” components located outside the
pressure vessel.
The structure of claim 4 is consistent with this inter-
pretation. Claim 4 is directed to a “Viscometer.” Id. at
col. 12 l. 52. Limitations 4(a) and 4(b), however, are specif-
ically tailored to aspects of the pressure vessel within the
viscometer, whereas limitation 4(c) does not refer to the
“pressure vessel.” Id. at col. 12 ll. 58–59. Reading these
limitations together, a skilled artisan would interpret lim-
itations 4(a) and 4(b) to refer to the pressure vessel and
limitation 4(c) to refer to the “bottom section” the viscome-
ter.
This reading also is consistent with the specification,
which explains that the primary “means for driving” the
rotor is magnetic coupling: “A motor or gearbox drives
magnet mount 40 to rotate carrying driving mag-
net 38 . . . . Due to the magnetic coupling between driving
magnet 38 and coupling magnet 34, rotor 51 rotates at the
same revolving speed as magnet mount 40 does.” Id. at
col. 5 ll. 42–47; see also id. at col. 8 ll. 24–30, col. 10
ll. 36–42. The motor or gearbox, magnet mount 40, and
driving magnet 38 are located outside the pressure vessel.
See id. at FIGS. 1–3, col. 3 ll. 7–10. Because some of these
components are outside the pressure vessel, they cannot be
located in the bottom section of the pressure vessel. In-
stead, these components must be located in the bottom sec-
tion of the viscometer.
Grace’s remaining arguments are unpersuasive. Grace
argues that “top section” of the pressure vessel in limita-
tion 4(a) means that “bottom section” in limitation 4(e) re-
fers to the pressure vessel, and “top section” and “bottom
section” in limitation 4(e) must both refer to the pressure
vessel to facilitate communicating pressure between the
two. Appellant’s Br. 58–59; Appellant’s Reply Br. 31. We
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disagree. Limitation 4(e), consistent with our analysis
above, can be understood as simply requiring that the en-
larged chamber be positioned between the top section of the
pressure vessel and bottom section of the viscometer.
Grace also argues that the district court’s interpreta-
tion of “means for driving” to include “magnetic coupling
(magnet mount, gear box or motor, driving magnet, cou-
pling magnet)” (1) excludes the patent’s preferred embodi-
ments because certain components are outside of the
pressure vessel and thus can cannot be located in the “bot-
tom section,” Appellant’s Br. 63–65; (2) renders claim 14
impossible by requiring the magnetic coupling to be inside
the pressure vessel’s bottom section, Appellant’s Br. 65–66;
and (3) requires the electric motor to be inside the pressur-
ized bottom of the pressure vessel, even though a motor
cannot work while submerged in drilling fluid, Appellant’s
Br. 66–67. But for all of these arguments, Grace’s logic is
circular. Each argument relies on Grace’s preferred inter-
pretation that “bottom section” refers to the pressure ves-
sel, not the viscometer. Under the correct interpretation
that “bottom section” refers to the viscometer, the preferred
embodiments are not excluded and there is no conflict with
claim 14.
Finally, Grace relies on claim 1 and a stipulation be-
tween the parties to argue that the ’877 patent uses the
terms “lower section” and “bottom section” interchangeably
to refer to the bottom section of the pressure vessel. Appel-
lant’s Br. 60 (citing J.A. 1297). We disagree. The stipula-
tion Grace cites only modifies claim 1, not claim 4, and only
changes “bottom section” in claim 1 to “lower section” to
address the lack of antecedent basis. Appellee’s Br. 50–51.
Additionally, when Chandler argued at the Markman hear-
ing that “lower section” in claim 1 refers to the pressurized
device and “bottom section” in claim 4 refers to the viscom-
eter, J.A. 1479–80 (75:8–76:10), Grace’s counsel asked the
agreement to be withdrawn because Grace did not intend
for the stipulation to be used against it in relation to
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claim 4, J.A. 1489 (85:13–23). The stipulation thus does
not make clear that the terms “lower section” and “bottom
section” are used interchangeably in the ’877 patent, and
we are not persuaded that the patentee intended the terms
to be interchangeable.
For the foregoing reasons, we affirm the district court’s
construction of “means for driving said rotor to rotate lo-
cated in at least one bottom section.”
B. Grace’s Proposed Construction
We also reject Grace’s proposed alternate construction
for the means for driving limitation. Grace’s proposed con-
struction comprises two parts: (1) “means for driving” can
be just the “magnet holder” alone because the magnet
holder individually qualifies as a “means for driving,” Ap-
pellant’s Br. 67–68, Appellant’s Reply Br. 22–28; and
(2) the “direct drive” alternative to magnetic coupling as
the “means for driving” should be construed such that it
“attaches in the bottom section to the rotor to rotate it,”
rather than “at the bottom of the cell body,” Appellant’s Br.
69. We disagree.
1. Magnet Holder
Grace asserts that every structure involved in relaying
power to the rotor individually qualifies as a separate
“means for driving.” See Appellant’s Reply Br. 26. But
Grace misreads the specification. See, e.g., ’877 patent
col. 5 ll. 42–47; see also id. at col. 8 ll. 24–30, col. 10
ll. 36–42. The specification provides no details suggesting
that the magnet holder, for example, could be solely re-
sponsible, without additional structure, for rotating the ro-
tor. The other magnetic coupling components also are
required to rotate the rotor.
Grace’s argument that its interpretation prevents ex-
cluding the preferred embodiments is, again, circular. The
district court’s interpretation of “means for driving” only
excludes the preferred embodiments if the claimed “bottom
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section” refers to the pressure vessel, not the viscometer.
But because we have determined that “bottom section” re-
fers to the bottom section of the viscometer, the other com-
ponents involved in the magnetic coupling “means for
driving” may be located inside or outside the pressure ves-
sel. See discussion supra Discussion § II.A. We thus disa-
gree with Grace’s attempt to define the “means for driving”
as any individual component that relays power to the rotor.
2. Direct Drive
Grace argues that the district court erred in reading a
limitation from the written description into the means for
driving limitation by requiring the “direct drive” to be “at
bottom of cell body.” Appellant’s Br. 69. Grace argues that
means-plus-function claims must be limited to disclosed
structures and equivalents, not locations of disclosed struc-
tures. Appellant’s Reply Br. 31–32. We disagree.
The ’877 patent explains that magnetic coupling can be
used to drive the rotor to rotate, or the rotor “could be
driven to rotate with any means such as directly driven at
the bottom of the cell body with dynamic seal, etc.” ’877
patent col. 11 ll. 41–43 (emphasis added). The disclosed
structure is, therefore, magnetic coupling or a direct drive
at the bottom of the cell body, and known equivalents, con-
sistent with the district court’s opinion. See Claim Con-
struction Order, 2021 WL 2711987, at *7–8. We reject
Grace’s attempt to disassociate the disclosed structure
from the location of the disclosed structure. The specifica-
tion indicates that the invention envisioned and claimed by
the patentee was a direct drive attached to the bottom of
the cell body. See, e.g., NOMOS Corp. v. BrainLAB USA,
Inc., 357 F.3d 1364, 1367–68 (Fed. Cir. 2004) (affirming the
district court’s construction of a “means for generating at
least one ultrasound image” as requiring the ultrasound
probe to be mounted to the treatment table by a fixation
device).
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CONCLUSION
We have considered Grace’s remaining arguments and
do not find them persuasive. For the foregoing reasons, we
vacate the district court’s determination that “enlarged
chamber” is indefinite, vacate the district court’s invalidity
determinations based thereon, and remand for further pro-
ceedings consistent with this opinion. We affirm the dis-
trict court’s construction of “means for driving said rotor to
rotate located in at least one bottom section” and the dis-
trict court’s judgment based thereon.
AFFIRMED-IN-PART, VACATED-IN-PART, AND
REMANDED
COSTS
No costs.
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