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BORGWARNER, INC. v. NEW VENTURE GEAR
December 27, 2002
BORGWARNER, INC., AND BORGWARNER TORQTRANSFER SYSTEMS, INC., PLAINTIFFS,
NEW VENTURE GEAR, INC., DEFENDANTS.
The opinion of the court was delivered by: Edward A. Bobrick, United States Magistrate Judge.
Plaintiff BorgWarner charges defendant New Venture Gear with infringing
U.S. Patents Nos. 5,407,024 ("patent 024");
5,485,894 ("patent 894");
6,000,488 ("patent 488"); and 6,062,330 ("patent 330"). This matter was
referred to this Magistrate Judge for the purposes of conducting a
Markman hearing and construing the disputed claims of the
patents-in-suit. See Markman v. Westview Instruments, Inc., 52 F.3d 967,
979 (Fed.Cir. 1995). The patents-in-suit deal with fourwheel drive
systems employing active-on-demand transfer eases that automatically
control the amount of torque transferred to front and rear wheels. A
transfer case is an auxiliary transmission designed to permit the drive
from the engine of a vehicle to be operatively split to both the front
and rear driving axles. The patents-in-suit disclose a transfer case
design that is electronically controlled by a microcontroller.
The microcontroller transfer case is the substance of these patents.
Four-wheel drive allows vehicles to operate better on slippery road
surfaces, or in off-road conditions. Compared to two wheel drive
systems, however, four-wheel drive systems can result in lower gas
mileage, and decreased handling and performance in certain situations.
Thus, a part-time four-wheel drive system has the advantage of allowing
the operator to select the drive system based on the driving conditions
at hand. The operator engages the four-wheel drive system by lever or
switch and, within the transfer case, a clutch is engaged that locks the
front and rear drive shafts together. The speed of the front and rear
wheels becomes equal.
In an on-demand four-wheel drive system, the clutch in the transfer
case engages and disengages automatically. This can be an advantage over
the part-time, operator-initiated system because it is thought that the
operator will not always know when driving conditions call for, or do not
call for, four-wheel drive. On-demand transfer cases can be active or
reactive. A reactive transfer case employs a mechanical system, such as a
viscous clutch, which engages, or reacts, when there is a difference is
speed between the front and rear drivelines. A viscous coupling is
basically a drum filled with a thick fluid that houses several closely
fitted, thin steel discs. One set of the discs is connected to the front
wheels and the other to the rear. As one axle begins to demand more
torque, the fluid heats up and its viscosity changes. This change in
viscosity affects the discs and torque is split according to the actual
demands of the axles.
Active on-demand transfer cases employ sensors that monitor traction
needs and automatically adjust the delivery of power to the wheel.
Sensors may monitor various factors — such as vehicle speed, wheel
slip, accelerator pedal angle, or braking — for which a passive
system cannot account. The reaction is quicker than in the passive
systems, and some handling problems are eliminated as a result. While
this can be an advantage, it can also be a disadvantage in some off-road
conditions where the shift might be too abrupt. In addition, as it is a
more complex system, it can be more costly.
The patents-in-suit describe an active on-demand system. BorgWarner
states that its: "transfer cases have primary and secondary output shafts
which drive the primary and secondary axles, front and rear output speed
sensors, a modulating clutch to transfer torque from the rear output to
the front output when necessary, a drive and a driven sprocket, a chain
connecting the two sprockets, a planetary reduction gear for high and low
range, and a dog clutch for selecting the range." (Plaintiff's Markman
Brief, at 7). BorgWarner goes on to explain some of this as follows:
The modulating clutch is a friction plate clutch that
includes plates that rotate with the primary output
shaft and plates that rotate with the secondary output
shaft. The plates are interleaved together so that
when the plates are engaged (i.e., pressed together)
torque is transferred from the primary output to the
secondary output. The amount of torque transferred
will vary with the amount of engagement. The
patents-in-suit teach that the clutch actuator can be
electromagnetic, hydraulic, or pneumatic.
A microcontroller controls the amount of clutch
engagement and disengagement, The microcontroller is
programmed with a control strategy that uses
information about vehicle and road conditions to
determine when to engage and disengage the modulating
clutch. More specifically, the microcontroller first
determines the amount of slip (i.e. the difference in
rotational speeds) between the front and rear
drivelines in determining whether to engage the
clutch. A certain amount of slip is acceptable, and in
fact, in cornering situations is required. However,
when the slip exceeds a certain amount, vehicle
handling and performance are affected adversely. The
microcontroller determines when the amount of slip is
too much. Specifically, the microcontroller receives
signals from sensors that are indicative of the
rotational speed of the front and rear drivelines.
These sensors can be located in the transfer case or
at the wheels. From these signals, the microcontroller
is able to determine the slip or the speed difference
between the front and the rear drivelines.
Once the amount of slip has been determined, the
microcontroller uses that information to determine
whether the modulating clutch should be engaged or
disengaged. Specifically, the amount of slip is
compared to a predetermined amount of allowed slip. If
the actual slip is greater than the predetermined
amount, the microcontroller generates a signal that
causes the modulating clutch to be engaged a discrete
amount. The microcontroller then repeats its
analysis. If the slip is still above the predetermined
amount, the amount of engagement of the modulating
clutch is increased again. However, if the slip is
below the predetermined of threshold amount, the
modulating clutch is disengaged by a discrete amount.
Thus, the torque is increased and decreased in a
stepwise manner. This incremental engagement and
disengagement control is a closed loop control
strategy that is repeated over and over again as long
as the vehicle is in the on demand mode. The constant
monitoring and stepwise clutch engagement and
disengagement result in an on demand four-wheel drive
system that operates without any driver input. In
fact, the driver is unaware of this constant
monitoring and engagement/disengagement process.
The patents-in-suit disclose that one technique for
applying the incremental control strategy is to use
pulse width modulation ("PWM") to control the amount
of engagement applied by an electrical clutch
actuator. In PWM, the voltage is pulsed to the
electrical device to control the amount of power
applied. For example, applying five volts to an
electrical device will impart about one-half the power
that ten volts will provide. However, the same reduced
amount of power can be generated with ten volts by
leaving it on for 50% of the time, i.e., turning it on
and off so that the electrical device receives five
volts instead of ten. This method of power application
is called PWM because pulses of full voltage are
used, but the width of the pulse (i.e., the time
of the pulse) is adjusted to affect the
overall average power.
Other vehicle operating conditions that can be
utilized by the BorgWarner control strategy include
the vehicle speed, throttle position (i.e.,
acceleration), brake application, and steering angle
(i.e., cornering). The control strategy may utilize
the vehicle speed by varying the predetermined amount
of allowed slip depending on the vehicle speed. The
control strategy may also utilize acceleration.
Specifically, a throttle position sensor may be used
to determine the throttle position that is indicative
of the acceleration. The throttle position is used to
determine if the clutch should be engaged to provide
better acceleration. The control strategy may further
utilize a brake sensor to determine if the vehicle is
braking. The control strategy may use information
about the steering angle for modifying the measured
amount of slip to account for cornering.
The patents-in-suit also disclose that a minimum
standby clutch engagement may be utilized in the on
demand transfer case system. This standby engagement
establishes a minimum torque transfer amount through
the modulating clutch. The minimum engagement is
sometimes called "touch off torque" or "preload." The
purpose of the minimum engagement is to provide faster
reactions time to prevent wind up or clunking that
otherwise occurs when engagement begins.
(Plaintiff's Markman Brief, at 7-10). Obviously, NVG parts company with
BorgWarner at significant junctures in this explanation of the
patents-in-suit. Specifically, there are twelve claim terms in the three
patents.-in-suit which are in dispute. For three days beginning September
10, 2002, this court held a Markman hearing at which the parties
presented their respective interpretations of the twelve patent claims at
issue. See Markman v. Westview Instruments, Inc., 52 F.3d 967, 979
(Fed.Cir. 1995) (en banc), aff'd. 517 U.S. 370 (1996). The parties
presented their cases for their interpretations of these twelve claim
terms and the court must construe those claim terms in accord with the
following applicable law.
III. CLAIM CONSTRUCTION STANDARDS
In Markman, the Federal Circuit held, and the Supreme Court affirmed,
that it is the courts' responsibility as a matter of law to construe the
claims of patents for the jury. 52 F.3d at 979. Claim construction is
"the process of giving proper meaning to the claim language," the
fundamental process that "defines the scope of the protected invention."
Abtox, Inc. v. Exitron Corp., 122 F.3d 1019, 1023 (Fed.Cir. 1997). Claim
construction analysis must begin with the words of the claim, which
define its scope. Teleflex, Inc. v. Ficosa North America Corp.,
299 F.3d 1313, 1324 (Fed.Cir. 2002). "[T]he language of the claim frames
and ultimately resolves all issues of claim interpretation." Abtox, Inc.
v. Exitron Corp., 122 F.3d 1019, 1023 (Fed.Cir. 1997).
The words used in the claims are interpreted in light of the intrinsic
evidence of record, including the written description, the drawings, and
the prosecution history, if in evidence. Teleflex, 299 F.3d at 1324. The
intrinsic evidence may provide context and clarification about the
meaning of claim terms. Id. In the absence of an express intent to impart
a novel meaning to claim terms, there is a "heavy presumption" that a
claim term carries its ordinary and customary meaning. Teleflex, 299 F.3d
at 1325. The ordinary meaning of a claim term may be determined by
reviewing a variety of
sources, including the claims themselves, other
intrinsic evidence including the written description and the prosecution
history, and dictionaries and treatises. Id. (citations omitted).*fn1 In
all cases, however, the ordinary meaning must be determined from the
standpoint of a person of ordinary skill in the relevant art. Id. In this
case, the parties inform us that one of "ordinary skill" in the art is a
person with a Bachelor of Science Degree in engineering, with several
years of experience in building and designing transfer cases. At the
Markman hearing, the parties indicated, however, that expert testimony
would not be necessary to their presentations, and neither had their
expert attend the proceedings. Nevertheless, the parties referred
throughout the proceedings to interpretations based on the understanding
of one skilled in the art. While it is true that both sides included
reports from their respective experts, those reports — obviously
— simply supported the interpretations the parties advanced. In a
situation where the parties call upon the court to interpret a dozen
intricate claims, some of which are interrelated,*fn2 in an area outside
the court's expertise, live testimony, with opportunity for
cross-examination and questions from the court would have been of real
Of all the intrinsic evidence, courts have indicated that the
specification is the "single best guide to the meaning of a disputed
term." Vitronics, Corp. v. Conceptronics, Inc., 90 F.3d 1576, 1582 (Fed.
Cir. 1996). "Usually, it is dispositive." Id. In Teleflex, the court
indicated that "[o]ne purpose for examining the specification is to
determine if the patentee has limited the scope of the claims." 299 F.3d
at 1325. As an example of such an instance, the court said "an inventor
may choose to be his own lexicographer if he defines the specific terms
used to describe the invention with reasonable clarity, deliberateness,
and precision." Teleflex, 299 E.3d at 1325. In addition, the
specification may be consulted to resolve ambiguity if the ordinary and
customary meanings of the words used in the claims are not sufficiently
clear to allow the scope of the claim to be determined form the words
alone. Id "The patentee may demonstrate an intent to deviate from the
ordinary and accustomed meaning of a claim term by including in the
specification expressions of manifest exclusion or restriction,
representing a clear disavowal of claim scope." Id.
On the other hand, while the claims must be read in view of the
specification, limitations from the specification are not to be read into
the claims. Id. at 1326. "That claims are interpreted in light of the
specification does not mean that everything expressed in the specification
be read into all the claims." Raytheon Co. v. Roper Corp.,
724 F.2d 951, 957 (Fed.Cir. 1983). Quoting SRI International v.
Matsushita Electric Corp., 775 F.2d 1107, 1121 (Fed.Cir. 1985), the
Teleflex court sought to explain this seeming contradiction:
If everything in the specification were required to be
read into the claims, or if structural claims were to
be limited to devices operated precisely as a
specification-described embodiment is operated, there
would be no need for claims. Nor could an applicant,
regardless of the prior art, claim more broadly than
that embodiment. Nor would a basis remain for the
statutory necessity that an applicant conclude his
specification with "claims particularly pointing out
and distinctly claiming the subject matter which the
applicant regards as his invention." 35 U.S.C. § 112.
It is the claims that measure the invention.
299 F.3d at 1326. The Teleflex court distilled these concerns to hold
that "claims take on their ordinary meanings unless the patentee
demonstrated an intent to deviate from the ordinary and accustomed
meaning of a claim term by redefining the term or by characterizing the
invention in the intrinsic record using words or expressions of manifest
exclusion or restriction, representing a clear disavowal of the claim
scope." 299 F.3d at 1327. Not surprisingly, with such language as their
guide, the parties have engaged in a rather spirited disagreement over
the role of the specification in the construction of the claims.
More recently, the Federal Circuit addressed this seemingly ambiguous
area of law in Texas Digital Systems, Inc., 308 F.3d 1193 (Fed.Cir.
2002), where it held that:
the intrinsic record also must be examined in every
case to determine whether the presumption of ordinary
and customary meaning is rebutted. Indeed, the
intrinsic record may show that the specification uses
the words in a manner clearly inconsistent with the
ordinary meaning reflected, for example, in a
dictionary definition. In such a case, the
inconsistent dictionary definition must be rejected.
In short, the presumption in favor of a dictionary
definition will be overcome where the patentee, acting
as his or her own lexicographer, has clearly set forth
an explicit definition of the term different from its
ordinary meaning. Further, the presumption also will
be rebutted if the inventor has disavowed or
disclaimed scope of coverage, by using words or
expressions of manifest exclusion or restriction,
representing a clear disavowal of claim scope.
308 F.3d at 1204 (emphasis added, citations omitted). It would appear,
then, that the intrinsic record, including the specification, would
generally "trump" the claim language in construing the claim. The court,
however, went on to caution:
Consulting the written description and prosecution
history as a threshold step in the claim construction
process, before any effort is made to discern the
ordinary and customary meanings attributed to the
words themselves, invites a violation of our precedent
counseling against importing limitations into the
claims. For example, if an invention is disclosed in
the written description in only one exemplary form or
in only one embodiment, the risk of starting with the
intrinsic record is that the single form or embodiment
so disclosed will be read to require that the claim
terms be limited to that single form or embodiment.
Indeed, one can easily be misled to believe that this
is precisely what our precedent requires when it
informs that disputed claim terms should be construed
in light of the intrinsic record. But if the meaning
of the words themselves would not have been understood
to persons of skill in the art to be limited only to
the examples or embodiments described in
the specification, reading the words in such a confined
way would mandate the wrong result and would violate
our proscription of not reading limitations from the
specification into the claims.
308 F.3d at 1204-05 (emphasis added, citations omitted). It would seem,
however, that there will always be a tension in claim construction
between reference to the claim language and reference to the
specification, especially given what the Federal Circuit itself suggests
is misleading precedent.
That being said, there are four patents involved in this dispute, with
twelve disputed claim interpretations. The parties briefed these disputes
prior to the commencement of the three-day Markman hearing.
Unfortunately, at least one of the disputes raised at the hearing had not
been briefed by the parties. In addition, some of the parties' claim
interpretations were changed either during or following the hearing,
rendering much of the exposition that went on prior to the change of no
import. Following the hearing, the parties were given one more
opportunity to set forth their arguments in post-Markman briefs. Based on
this record, then, the court endeavors to interpret the disputed claims.
III. CONSTRUCTION OF DISPUTED CLAIMS
1. "Incrementally Engaging and Disengaging"
Claims 1, 23, 33, 62, 64, and 66 of patent `024 recite that the
modulating clutch is incrementally engaged when a measured speed
difference between the primary and secondary drivelines is greater than a
predetermined amount and is incrementally disengaged when the speed
difference between these drivelines is below that amount. The parties'
dispute is over the meaning of the phrase "incrementally engaging and
"Incrementally engaging and disengaging" is a closed
loop control strategy that incrementally increases the
clutch engagement when the slip is above a
predetermined amount and incrementally decreases-the
clutch engagement when the slip is below that amount.
This incrementally engaging and disengaging is done in
discrete steps, which may be the same or different
sizes. (Plaintiff's Markman Brief, at 14).
"Incrementally engaging and disengaging" means
discrete steps that are fixed (re-set prior to using
the system). The size of the step is not dependent on
the magnitude of the wheel slip and therefore not
continuously variable. (Markman Reply Brief of NVG, at
The issue regarding this claim distills down to the definition of
"incrementally": whether it can describe steps of varying sizes or must
mean step of fixed sizes. As noted above, we begin with the "heavy
presumption" that a claim term carries its ordinary and customary
meaning. Teleflex, 299 F.3d at 1325. To discern the ordinary and
customary meaning of a term we may look to dictionary definitions of the
word. Kopykake Enterprises, Inc. v. Lucks Co., 264 F.3d 1377, 1382 (Fed.
Cir. 2001). Dictionaries, as noted earlier, may always be relied on by
the court to determine the meaning of the claim terms "so long as the
dictionary definition does not contradict any definition found in or
ascertained by a reading of the patent documents." Id., quoting
Vitronics, 90 F.3d at 1584 n. 6.
In this case, the parties offer a buffet of dictionary definitions.
BorgWarner's sampling is geared toward a definition of "increment" as
"the finite increase of a variable quantity." Webster's New Twentieth
Century Dictionary, at 926 (2nd ed. 1978).*fn3
argues that the "ordinary and customary meaning of the word
`incrementally' refers to stepwise changes and that these changes may be
variable (or different) sizes." (Plaintiff's Markman Brief, at 15). Not
surprisingly, NVG's selections refer to changes in steps of fixed or
constant sizes. For example, NVG points to the Oxford Modern English
Dictionary's definition of increment as "an increase or addition, esp.
one of a series on a fixed scale." (Markman Brief of NVG, at 10, citing
Oxford Modern English Dictionary, at 539 (1992)). From the court's
perspective, the difference is merely one of context.
BorgWarner argues that words in a claim are entitled to their broadest
dictionary definition, citing Rexnord Corp. v. Laitram Corp.,
274 F.3d 1336, 1342 (Fed.Cir. 2001). (Plaintiff's Post Markman Brief, at
2). We cannot disagree that, generally, an increment could be of
"variable quantity, as BorgWarner argues, of different sizes. There is a
specific context here, however, which a definition such as that of the
Oxford Modern English Dictionary addresses. Beyond that, we are not
really resolving the issue of what "increment" means, but what
"incrementally" means as used to describe "engaging and disengaging."
We are dealing with "increment" as the root of the adverb
"incrementally," which is used to modify "engaging" and "disengaging."
While the noun "increment" may refer to a single, step, addition, or unit
of increase which may be of any size, the adverb "incrementally" must be
applied to the process of engaging and disengaging. Then, we are not
speaking of an "increment," but a potential series of increments. Once the
size of an increment is determined, "incrementally" would refer to a
series of steps or additions of that determined size: one increment
following another. Ordinarily and customarily, one might refer to such a
process as occurring "in increments of . . .," followed by a single
amount, as in increments of 5." It is doubtful, or would at least be
rare, that the phrase would ever be followed varied amounts, as in
increments of 5, 7, and 10."
As BorgWarner describes that process, once the microcontroller
determines the amount of slip, it compares it to a predetermined amount
of allowed slip. If the actual slip is greater than the predetermined
amount, the microcontroller causes the modulating clutch to be engaged a
"discrete" amount, and the analysis is repeated. If the slip is still
above the predetermined amount, the amount of engagement of the
modulating clutch is increased again; if the slip is below the
predetermined of threshold amount, the modulating clutch is disengaged,
again by a "discrete" amount. Certainly, these "discrete amounts" would
be "increments," but to suggest they would be of a random or variable
size would be counterintuitive. If they could be, the analysis spoken of
could simply be performed a single time and the slip corrected for in
whatever "increment" was called for. According to BorgWarner, such a
single step correction is "very
apparent to the driver and undesirable."
(Plaintiff's Markman Brief, at 8-9 n. 5). It would seem that at least one
supposed innovation of the patents-in-suit, the unnoticed correction of
slippage, would be defeated by the interpretation BorgWarner advances
This dispute, then, is resolved by the ordinary and customary meaning
of "incrementally engaging." Clearly, the "increments" by which the
clutch engages or disengages must be of the same size. "Incrementally
engaging and disengaging" means discrete, fixed steps.
2. "Clutch Means", "Modulating Clutch Means", and "Adjustable Clutch
Claims 1, 23, 33, 59, 62, and 64 all recite some form of modulating
clutch means. For example, Claim 1 recites:
a transfer case having a primary output shaft adapted
to drive said primary wheels, a secondary output shaft
adapted to drive said secondary wheels, modulating
clutch means for selectively transferring torque from
said primary output shaft to said secondary output
shaft and substantially inhibiting torque transfer
from said primary output shaft to said secondary
Claims 23, 33, 62, and 64 all include similar limitations, which may be
phrased "clutch means" or "adjustable clutch means." The use of the term
"means" in each of the claim limitations, along with the recitation of a
function, such as "selectively transferring torque . . ." raises the issue
of the applicability of 35 U.S.C. § 112, paragraph 6, which deals
with "means-plus-function" claims.*fn5 The parties' disagreement over
the interpretation of this claim concerns the applicability of
"means-plus — function" interpretation rules.
"Modulating clutch means" is a clutch that can
transfer different amounts of torque from the primary
output shaft to the secondary output shaft. The
"modulating clutch means" may be a
disk-pack-friction-plate clutch. The "modulating
clutch means" does not include an actuator and may be
actuated by any type of acceptable actuator.
(Plaintiff's Markman Brief, at 20).
A means-plus-function element, properly interpreted
under § 112 ¶ 6 to be the structure described
in the specification that performs the recited
function, or its equivalent. The structure for
performing the function must include clutch assembly
124, which includes an electromagnetic ball/ramp
actuator, the drive and driven sprockets 160 and 166
and chain 164. (Markman Brief of NVG, at 16).
The use of the word "means" triggers a presumption that the inventor
used the term advisedly to invoke the statutory mandate for
"means-plus-function" clauses. Allen Engineering Corp. v. Bartell
Industries, 299 F.3d 1336, 1347 (Fed. Cir. 2002). This area of patent law
is a bit counterintuitive from the court's perspective. According to the
[t]he question whether a claim element triggers
section 112(6) is ordinarily not a difficult one.
Claim drafters conventionally use the preface "means
for" (or "step for") when they intend to invoke
section 112(6), and there is therefore seldom any
confusion about whether section 112(6) applies to a
True, there are two circumstances, however, in which courts have
allowed that the presumption is not controlling. First, if a claim
element employs the word "means" but recites no corresponding function,
then § 112 ¶ 6 is not applicable. Allen Engineering, 299 F.3d at
1347. Second, even if the claim recites a function, if it also recites
sufficient structure or material for performing that function, § 112
¶ 6 does not apply. Id. It is this second circumstance that
BorgWarner hopes to take advantage of in this case: according to it, a
"modulating clutch means" is a structure sufficient to perform the stated
functions of "selectively transferring torque . . . and substantially
inhibiting torque . . ." from the primary output shaft to the secondary
output shaft. NVG disagrees, but the difficulty here seems to be that
both sides have support in the applicable case law.
Part of the problem here stems from somewhat murky, or at least less
than specific, case law. As already noted, the court in Allen
Engineering held that § 112 ¶ 6 did not apply if the claim
element "recites sufficient structure or material for performing that
function." 299 F.3d at 1347. Then, the court went on to state that "[a]
claim term recites sufficient structure if the term, as the name for the
structure, has a reasonably well-understood meaning in the art." Id. In
this case, we would be hard-pressed to disagree with BorgWarner that the
term "modulating clutch" has a well understood meaning in the art.
Understandably, then, BorgWarner argues that "[t]he clear reasoning of
Allen Eng'g dictates that "modulating clutch means for . . ." does not
invoke § 112 ¶ 6 because it recites structure that has a
reasonably understood meaning in the art." (Plaintiff's Post Markman
Hearing Brief, at 10).
While the language of Allen Engineering might appear to allow such an
argument, we feel it skips a step. The court was relying in part on Watts
v. XL Systems, Inc., 232 F.3d 877 (Fed.Cir. 2001), which stated that
"[a]s an aid in determining whether sufficient structure is in fact
recited by a term used in a claim limitation, this court has inquired
into whether the term, as the name for structure, has a reasonably well
understood meaning in the art." 232 F.3d at 880-81 (emphasis added). As
such, we begin with the term, and we first query whether that term has a
reasonably well understood meaning in the art. Certainly, "modulating
clutch" is such a term. The analysis is not complete, however: the term
may have a reasonably understood meaning, but it must "be understood by
one skilled in the art as being adequate to perform the recited
function." Budde v. Harley-Davidson, Inc., 250 F.3d 1369, 1377 (Fed.
Cir. 2001). Based on the court's reading of these cases, it is not enough
that the term at issue simply have a reasonably well understood meaning
in the art, as it is understood, it must also be adequate to perform the
With this understanding in mind, we can review what evidence the
parties have compiled to support their contentions as to whether
"modulating clutch" is a sufficient structure to perform the recited
function. They rely, essentially, on expert reports (Plaintiff's Markman
Brief, at 20-21; Markman Brief of NVG, at 20-21) although, as noted
above, neither party presented expert testimony at the Markman hearing.
As a result, the court is left to choose between dry statements, neither
of which is subject to questioning from the court or cross-examination.
BorgWarner, a "modulating clutch means" is a structure
sufficient to perform the stated functions of "selectively transferring
torque . . . and substantially inhibiting torque . . ." Its expert. John
Starkey explains that:
A "clutch" is a device that provides an interruptible
torque connection between two rotating elements. A
"clutch" can use positive contact, friction, magnetic
forces, or fluid pressure to transfer torques between
two elements. A "modulating clutch" is an even more
specific type of clutch that can transfer different
amounts of torque. The dictionary definition of
modulate is "to vary the amplitude." This is exactly
what the modulating clutch does, i.e., vary the amount
of torque transferred from none to full capacity. Such
clutches use magnetic fields, fluid pressure, or
friction plates to transfer the torque.
(Plaintiff's Markman Brief, at 20-21, citing App. V, Ex. A, pp. 6-7). NVG
argues that this structure — the modulating clutch — cannot
perform the function without an "actuator" which turns the clutch on and
off, relying on its expert, Jeffrey Stein. (Markman Brief of NVG, at 20,
citing Ex. 9a, ¶ 54). In his report, Mr. Stein stated:
a "friction clutch with multiple plates"— is
insufficient to perform the claimed function. One
reason . . . is because the this[sic] "friction clutch"
requires an actuator in order to "selectively"
transfer torques (or as stated in some of the claims,
"modulate or "adjust" torque levels). Dr. Starkey's
"friction clutch with multiple plates" . . . would fail
to perform this function this structure is missing an
actuation mechanism (e.g. the electromagnetic
actuation mechanism described in the specification).
Additionally, the recited function requires that the
torque is selectively transferred from the primary
output shaft to the secondary output shaft. a
"friction clutch" alone cannot accomplish this
function a chain and sprocket assembly is necessary to
transfer torque from the "friction clutch" to the
secondary output shaft.
(Id.). Indeed, another of BorgWarner's experts — in patent law if
not transfer cases — Gerald Bjorge, testified — tentatively,
as he put it — "that the term modulating clutch means by itself
would not recite enough structure to be a nonmeans plus function
element." (Markman Brief of NVG, Ex. 16, at 72). This automotive
engineering version of "he said, he said" culminated at the deposition of
BorgWarner's expert, who testified as follows:
Q: Now, what components make up that friction clutch
with multiple plates?
A: The components which transmit the torque through
Q: Can the friction plates transmit torque without an
actuator of some type?
A: Clearly they need other enabling components to
transmit the torque, but they are the ones that
transmit the torque through the clutch.
(Markman Brief of NVG, App., Ex. 11 at 123-24). This is the type of thing
that just goes back and forth and, unfortunately, the court did not have
the opportunity to question the experts, and perhaps force them to commit
to one position, at the Markman hearing. Significantly, though, for our
purposes, the plaintiff's expert testimony stops short of asserting that
the "modulating clutch" is sufficient to perform the recited function.*fn6
the evidence, and the varying opinions, it appears that,
while "modulating clutch" may have a well understood meaning in the art,
it is not a sufficient structure to perform the recited function.
Accordingly, we find that § 112, ¶ 6 is applicable.
Construction of a means-plus-function limitation involves two steps.
First, the court must identify the claimed function. Cardiac Pacemakers,
Inc. v. St. Jude Medical. Inc., 296 F.3d 1106, 1113 (Fed. Cir.
2002)(citing Telemac Cellular Corp. v. Topp Telecom, Inc., 247 F.3d 1316,
1324 (Fed.Cir.2001)). The court must construe the function of a
means-plus-function limitation to include the limitations contained in
the claim language, and only those limitations. Cardiac Pacemakers, 296
F.3d at 1113. The court may neither narrow the scope of the function
beyond the claim language, nor broaden the scope of the claimed function
by ignoring clear limitations in the claim language. Id. Here,
"modulating clutch means" must be interpreted to be the structure set
forth in the specification that performs the claimed function of
"selectively transferring torque from said primary output shaft to said
secondary output shaft and substantially inhibiting torque transfer from
said primary output shaft to said secondary output shaft."
Second, the court must determine what structure, if any, disclosed in
the specification corresponds to the claimed function. Id. In order to
qualify as corresponding, the structure must both perform the claimed
function, and clearly associate the structure with performance of the
function. Id. The court does this — or at least attempts to
— from the perspective of a person of ordinary skill in the art.
The parties, with some reliance on their respective experts, direct the
court to two different structures disclosed in the specification that
purportedly perform the claimed function. BorgWarner submits that:
the components that actually transfer torque and
inhibit the transfer of torque are the components of
the disc pack clutch assembly 150 described in the
specification. Those components include interleaved
friction plates or discs 152, clutch hub 155, and
annular housing 156.
(Plaintiff's Markman Reply Brief, at 14 (citing Patent `024, col. 8. ls.
52-58)). NVG claims that this interpretation ignores the requirement that
torque be selectively transferred, and that it be transferred between the
two shafts. As NVG would have it:
The specification makes clear that the claimed
function is performed by the clutch assembly 124
(including ball/ramp device), the chain drive
sprockets 160 and 166, and the drive chain 164. The
specification states that these components transfer
torque from the primary out put shaft 40 to the
secondary output shaft 26 of the transfer case when
energized, as is required by the claims.
(Markman Brief of NVG, at 21 (citing Patent `024, col.9, Is. 34-42).
BorgWarner criticizes this interpretation as confusing the performance of
the function with the enablement of that performance. Through several
rounds of briefing, the
parties offer no response to these respective criticisms.
In Asyst Technologies. Inc. v. Empak, Inc., 268 F.3d 1364 (Fed. Cir.
2001). upon which BorgWarner relies, the court attempted to differentiate
between a structure that actually performed a recited function, and one
that merely enabled the pertinent structure to operate as intended. In
that case, the recited function was "receiving and processing digital
information . . ." and the disputed structure was the line that
transferred the information. Obviously, the line did not "receive and
process" but merely enabled that function by transmitting, so it was found
not to be pertinent structure. 268 F.3d at 1370-71. BorgWarner fails to
expound upon the purported analogy to its position, however. (Plaintiff's
Markman Brief, at 14). The function at issue is the selective transfer of
torque between the two shafts. The structure cited by NVG is directly
involved in the function, along with the clutch. If"transferring" were
part of the function in Asyst. we suspect the line would be pertinent
structure. Accordingly, we must find that the structure for performing
the function must include clutch assembly 124, which includes an
electromagnetic ball/ramp actuator, the drive and driven sprockets 160
and 166 and chain 164.
We must address one final point regarding this claim dispute. After two
rounds of briefing, BorgWarner came up with a new argument at the
Markman hearing and in its post-Markman hearing brief: that NVG's
interpretation violates the doctrine of claim differentiation. Under the
doctrine of claim differentiation, there is a presumption that each claim
in a patent is different in scope, especially if "there is a dispute over
whether a limitation found in a dependent claim should be read into an
independent claim, and that limitation is the only meaningful difference
between the two claims." Ecolab, Inc. v. Paraclipse, Inc., 285 F.3d 1362,
1375 (Fed. Cir. 2002). BorgWarner submits that claim 1, an independent
claim, must be broader that its dependent claims, such as claim 10. It
argues that NVG's interpretation — that the "modulating clutch' of
claim 1 must have a "electromagnetic ball/ramp actuator" — renders
claim 1 impermissibly narrower than claim 10.
The doctrine of claim differentiation, however, only guides the court's
interpretation of the claims, it is not a "hard and fast rule of
construction." Kraft Foods, Inc. v. Int'l Trading Co., 203 F.3d 1362,
1368, (Fed. Cir. 2000). Indeed, it is settled law that independent claims
containing means-plus-function limitations do not have the same literal
scope as dependent claims reciting specifically the structure that
performs the stated function. Medtronic. Inc. v. Advanced Cardiovascular
Systems, Inc., 248 F.3d 1303, 1313 (Fed. Cir. 2001). In Laitram Corp. v.
Rexnord, Inc., the court held that "[a] means-plus-function limitation 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." 939 F.2d 1533, 1538, (Fed.Cir. 1991).
Thus, claim differentiation will not be applied to a situation where, as
here, a dependent claim recites the only structure disclosed in the
specification that could correspond to the means claimed in the
Accordingly, our interpretation of this claim,
then, remains unchanged: the structure for performing the function must
include clutch assembly 124, which includes an electromagnetic ball/ramp
actuator, the drive and driven sprockets 160 and 166 and chain 164.
3. "Means for Determining a Desired Speed Difference"
Claim 52 reads, in part, "means for determining a desired speed
difference between said primary output shaft speed and said secondary
output shaft speed." The parties agree that this limitation is a
"means-plus-function" element under § 112 ¶ 6. The dispute is
over what structure is disclosed in the specification for performing the
function of "determining a desired speed difference.
"Means for determining a desired speed difference
between said primary output shaft speed and said
secondary output shaft speed" is circuitry within a
microcontroller for determining a desired speed
difference between said primary output shaft speed and
said secondary output shaft speed. (Plaintiff's Markman
Brief, at 23).
A means-plus-function element, properly interpreted
under § 112 ¶ 6 to be the structure described
in the specification that performs the recited
function, or its equivalent. That structure is a
microprocessor with specific circuitry (i.e., programmed
with a specific algorithm) that determines the desired
speed threshold based on (1) whether the brakes are on or
off and (2) whether the transfer case is in high or low
gear. (Markman Brief of NVG, at 23).
As we interpret the parties' presentations, the dispute here is whether
the claim can be interpreted as broadly as a general "circuitry within
the microcontroller" or whether it must be interpreted to include
specific programming of that microcontroller circuitry. According to
BorgWarner, the structure that is disclosed in the specification for
performing the recited function is circuitry within the microcontroller,
which is described in detail in column 13, lines 52-68, of Patent `024.
(App. I, p. 27.). As BorgWarner explains:
It is commonly known among those of ordinary skill in
the art that the circuitry of the microcontroller
stores and implements the control programs and
routines, as well as facilitates the computations,
analyses, and generation of output signals. The
specification states that "the microcontroller
utilizes an interrupt driven program which functions
with four internal loops having distinct cycle times."
During the steps of one of the routines performed by
the microcontroller, "the maximum allowable drive
shaft speed difference" is determined. Also, "a
process step 254 determines the maximum allowable
wheel speed difference (which is indicative of wheel
slip) for the present vehicle speed inferred from the
speed of the drive shaft which is rotating more
slowly." Furthermore, this "desired speed difference"
is the "threshold" slip value "below which the system
does not take action to correct for wheel slip and
above which the system begins to correct for wheel
(Plaintiff's Markman Brief, at 23-24). NVG submits that the structure
that performs the recited function is a microcontroller programmed with
the specific algorithm disclosed in the specification.
In WMS Gaming, Inc. v. International Game Technology, 184 F.3d 1339
(Fed. Cir. 1999), the court dealt with a means-plus-function limitation
involving a microcomputer. As the court explained:
184 F.3d at 1348. The court held that, "[i]n a means-plus-function claim
in which the disclosed structure is a computer, or microprocessor,
programmed to carry out an algorithm, the disclosed structure is not the
general purpose computer, but rather the special purpose computer
programmed to perform the disclosed algorithm." 184 F.3d at 1349.
In this case, NVG contends that the only "disclosed algorithm" for
determining the desired speed difference employs brake and gear
The maximum allowable wheel speed difference for a
given vehicle speed (which is indicative of wheel
slip) is determined from that part, i.e., Part A, B,
C, or D of Section 1 of Table II which corresponds to
the then current operating conditions of the vehicle,
i.e., whether the brake switch is activated and
whether the transfer case is in high or low gear.
(Patent `024, col. 17, Is. 33-39). Under WMS Gaming, then, the disclosed
structure must be interpreted as the microcontroller programmed with a
specific algorithm that determines the desired speed threshold based on
(1) whether the brakes are on or off and (2) whether the transfer case is
in high or low gear.
BorgWarner argues that the specification also states that the desired
speed difference is related to the vehicle speed and the identity of the
overrunning shaft, and "may also be dependent upon, for example, steering
angle and braking." (Plaintiff's Markman Reply Brief, at 15 (citing
Patent `024, col. 2, Is. 46-49)). BorgWarner also submits the
specification contains still other algorithms that can be used, including
one involving steering angle (col. 10, 1. 64-col. 11, 1.2). (Plaintiff's
Markman Reply Brief, at 15 n. 15). At this point, the parties once again
descend into a "he said, she said" battle: NVG claims these are not
algorithms; BorgWarner says they are.
Through several rounds of briefing, unfortunately, neither party
expounds on their algorithm position, or offers any support for their
positions beyond conclusory assertions. (Plaintiff's Markman Reply Brief,
at 15 n. 15 ("the specification of the patents in suit makes clear that
there are many algorithms that can be used to determine the desired speed
difference"); Post Markman Hearing Brief of NVG, at 10 (describing
BorgWarner's citations as "merely part of the Summary" portion of the
specification" — despite the fact that not all cited portions were
in the Summary, and "not an algorithm that performs the claimed
function"); Plaintiff's Post Markman Hearing Brief, at 13 ("The
specification discloses multiple algorithms that may be used by the
microcontroller to determine the desired speed difference . . .")). The
parties leave the court to speculate as to what a person skilled in the
art would make of all these putative algorithms; whether such an
individual would understand they were to employ them to program the
microcontroller to determine the desired speed difference. Based on the
record the parties have developed, however, the court is constrained to
find the only algorithm to be found in the patent-as opposed to lists of
possible influencing factors which BorgWarner cites — determines the
desired speed threshold based on (1) whether the brakes are on or off and
(2) whether the transfer case is in high or low
gear. Accordingly, the
disclosed structure must be interpreted as the microcontroller programmed
with that specific algorithm.
4. "Means for Controlling Operation of Said Clutch Means
in Response to Predetermined Conditions"
Claim 59 provides, in part:
[i]n an adaptive four-wheel drive system including a
torque distributing system for four-wheel drive
operation having a primary drive and secondary drive
line, clutch means associated with said secondary
drive line, and means for controlling operation of
said clutch means In response to predetermined
conditions, a method for controlling clutch operation
determining primary drive line speed,
determining secondary drive line speed,
determining the speed difference between said primary
drive line speed and said ...