Thermal Dynamics v . TATRAS CV-04-152-PB 12/09/04
UNITED STATES DISTRICT COURT FOR THE DISTRICT OF NEW HAMPSHIRE
Thermal Dynamics Corporation
v. Civil N o . 04-152-PB Opinion N o . 2004 DNH 181 TATRAS, Inc.
MEMORANDUM AND ORDER
Thermal Dynamics Corporation claims that TATRAS, Inc. is
currently selling ridged electrodes that infringe U.S. Patent N o .
4,782,210 (“‘210 Patent”). In this Memorandum and Order, I
construe several disputed terms in plaintiff’s patent.
I . BACKGROUND
The ‘210 Patent claims a novel electrode design that was
intended for use in a plasma-arc torch. The first part of this
section describes what a plasma-arc torch is and how it operates.
The second part describes both the patented technology and the
specific claim that is at issue in this dispute. The third and final part describes the electrode design adopted by defendant:
a design plaintiff alleges infringes its patent.
A. The Plasma-arc Torch
A plasma-arc torch cuts and welds hard metal. It operates
by directing plasma1 onto a workpiece at varying temperatures.
The plasma produced by the torch is created by bringing a gas, in
its normal state, into contact with an electric current. The
electric current ionizes and superheats the gas, which is then
forced through a small orifice at the tip of the torch and onto a
workpiece. A superheated stream of plasma can approach
temperatures of 20,000ºC.
The electrical current that is used to heat the gas is
called a “pilot arc” and is generated by an electrode inside the
torch. This process is initiated when the electrode assumes a
negative charge. In this state, the electrode becomes a
“cathode.” The torch tip, in response, assumes a positive
charge, becoming an “anode.” When the torch is operating
properly, electrons jump the gap between the electrode (cathode)
and the torch tip (anode), creating an electrical current. When
1 Plasma is an ionized, superheated gas sometimes described as the fourth state of matter.
-2- gas travels through the current, it becomes plasma.
Before plaintiff developed the technology described in the
‘210 patent, the electrodes used in Plasma-arc torches had smooth
sides and required between 5 and 12 kilovolts (“KVs”) of starting
power to generate the “pilot arc.” The use of such a high
voltage was problematic both because it was a challenge to
consistently produce the required voltage when the plasma-arc
torch was first developed and because the required voltage caused
the electrodes to rapidly decay. The ‘210 patent attempted to
address these problems through an electrode design that allows a
lower voltage to be used in producing the plasma.
B. Plaintiff’s Electrode Design
The ‘210 patent claims an electrode with ridges that
facilitate pilot arching at lower energy levels of between 3-6
KV. The patent includes ten separate claims. Claim 1 is the
patent’s sole independent claim. Claims 2-10 are all dependent
claims. The parties agree that their dispute is limited to the
construction of portions of claim 1 . Those portions claim the
following:
In a plasma-arc system comprising spaced, electrically conductive electrode means defining an arc chamber therebetween, pilot arc voltage supplying means
-3- connected to said electrode means, and means for supplying a flow of plasma forming gas through said arc chamber, the improvement which comprises:
said electrode means including at least one electrode having at least one ridge being located substantially in said arc chamber and extending along said electrode so as to provide a path for arcing, thereby producing a longer wearing electrode.
In addition to its multiple claims, the ‘210 patent also
contains a lengthy description of the invention’s preferred
embodiment. This embodiment illustrates the electrode’s
preferred shape and identifies its location inside the torch.
See ‘210 Patent, Figure 1 . The electrode is depicted as a
cylinder with a domed top. The cylinder is situated in a
chamber, leaving space between the top portion of the electrode
and the body of the torch. Gas flows through the chamber and
over the tip of the electrode. The tip of the electrode is
situated directly behind the torch tip. The torch tip contains
an orifice through which plasma is released. The ridges that
comprise the invention are on the cylindrical side surface of the
electrode and have a lengthwise orientation.
C. Defendant’s Electrode Design
Defendant produces and sells its own electrode. Like the
plaintiffs’ electrode, defendant’s technology is intended for use
-4- in a plasma-arc torch. Additionally, like the preferred
embodiment described in Patent ‘210, defendant’s electrode has
ridges on the surface of a cylindrical-sided electrode. These
ridges, however, radiate from the center point on the electrode
tip and toward the back portion of the electrode but stop at the
point where the domed top of the electrode reaches its
cylindrical sides.
Whether this design infringes plaintiff’s patent will depend
in large part upon how I construe plaintiff’s patent claims. It
is to this task that I now turn.
II. STANDARD OF REVIEW
Claim construction presents a question of law for the court
to resolve. Markman v . Westview Instruments, Inc., 517 U.S. 3 7 0 ,
372 (1996); Liquid Dynamics Corp. v . Vaughan Co., 355 F.3d 1361,
1367 (Fed. Cir. 2004). The starting point is the language of the
claim itself. Id. “There is a ‘heavy presumption’ that the
terms used in claims ‘mean what they say and have the ordinary
meaning that would be attributed to those words by persons
skilled in the relevant art.’” Superguide Corp. v . DirecTv
Enters., Inc., 358 F.3d 8 7 0 , 874 (Fed. Cir. 2004) (quoting Tex.
-5- Digital Sys., Inc. v . Telegenix, Inc., 308 F.3d 1193, 1202 (Fed.
Cir. 2002). Dictionary definitions are “often useful” in
construing disputed patent terms. Id. at 875. Once a range of
possible meanings has been identified through the use of
dictionary definitions, the context in which a disputed term is
used in the claims and the specification must be carefully
scrutinized to determine the preferred interpretation. See Int’l
Rectifier Corp. v . IXYS Corp., 361 F.3d 1363, 1369-70 (Fed. Cir.
2004). While the specification must always be considered in this
process, claim terms ordinarily are not limited to the
embodiments disclosed in the specification. See Amgen Inc. v .
Hoechst Marion Roussel, Inc., 314 F.3d 1313, 1328 (Fed. Cir.
2003). Extrinsic evidence may also prove helpful but such
evidence may not be used to alter the meaning of a claim term
whose definition can be discerned from intrinsic evidence. C.R.
Bard, Inc. v . United States Surgical Corp., 388 F.3d 8 5 8 , 861
(Fed. Cir. 2004).
Although each claim in a patent is an independent invention,
dependant claims can aid in interpreting the scope of the claims
upon which they depend. Laitram Corp. v . NEC Corp., 62 F.3d
1388, 1391 (Fed. Cir. 1995). Under the doctrine of claim
-6- differentiation, where claims in the same patent use different
terms, those differences are presumed to reflect a difference in
the scope of the claims. Forest Laboratories, Inc. v . Abbot
Laboratories, 239 F.3d 1305, 1310 (Fed. Cir. 2001); see also
Ecolab Inc. v . Paraclipse, Inc., 285 F.3d 1362, 1375-76 (Fed.
Cir. 2002) (stating that under the doctrine of claim
differentiation “each claim in a patent is presumptively
different in scope”); Liebel-Flarsheim C o . v . Medrad, Inc., 358
F.3d 8 9 8 , 910 (Fed. Cir. 2004) (holding that the “presence of a
dependent claim that adds a particular limitation raises a
presumption that the limitation in question is not found in the
independent claim.”).
A court must depart from this methodology in two
circumstances. First, it must do so if the patentee has acted as
its own lexicographer by clearly defining the term in the
specification. In this situation, the court must adopt the
meaning selected by the patentee. See Inverness Med. Switz. GmbH
v . Princeton Biomeditech Corp., 309 F.3d 1365, 1371-72 (Fed. Cir.
2002). Second, it must do so if the patentee clearly surrendered
an interpretation during the prosecution of the patent. See
Superguide Corp., 358 F.3d at 875.
-7- I apply these interpretive standards in construing the ‘210
patent.
III. CLAIM CONSTRUCTION
The parties dispute the meaning of one term and two phrases
in claim 1 . They first disagree as to the meaning of the term
“arc chamber.” They next dispute the meaning of the phrase
“extending along said electrode so as to provide a path for
arcing.” Finally, they offer different interpretations of the
phrase “so as to provide a path for arcing, thereby producing a
longer wearing electrode.”
1. “Arc Chamber”
The parties agree that the patentees acted as their own
lexicographer by defining the term “arc chamber” as the area
between “a pair of spaced-apart electrodes . . . in which
electric arcs are to be formed.” ‘210 patent col. 2 , 1 1 . 59-61.
Plaintiff contends that this definition does not require
elaboration. Defendant, by contrast, argues that the
specification further limits the term to the area between the
cylindrical side surface of one electrode and the surface of
-8- another electrode.
Defendant’s argument fails because it is based on the flawed
premise that the ‘210 patent only covers plasma-arc systems that
use cylindrical electrodes. This premise is plainly wrong.
Claim 1 does not limit the shape that an electrode must take.
Indeed, dependant claim 2 claims “the invention of claim 1
wherein said electrode is of generally rod shape so that the
surface is cylindrical.” ‘210 patent, col. 6, l l . 57-59. In
cases like this, where a dependant claim contains a limitation
that is not expressed in an independent claim, a presumption
exists that the independent claim is not subject to the
limitation described in the dependant claim. See Liebel-
Flarsheim Co., 358 F.3d at 910. Defendant has failed to identify
sufficient evidence to overcome this presumption. Thus, I reject
its argument that the patentee’s definition of arc chamber should
be further limited to the area that lies between the cylindrical
side surface of one electrode and the surface of another
electrode.
B. “Extending Along said Electrode so as to Provide a Path for Arcing”
Claim 1 also states that a ‘210 electrode must have at least
-9- one ridge “extending along said electrode so as to provide a path
for arcing.” ‘210 patent col. 6, 1 1 . 53-54. Defendant proposes
alternative contextual meanings for the term “along.” First, it
argues that dictionary definitions and the figures that
illustrate the invention’s preferred embodiment demonstrate that
“along” means “lengthwise over the longest side surface.”
Somewhat less restrictively, it contends that the patent’s
prosecution history demonstrates that “along” means “over the
side surface.” I examine each argument in turn.
Neither party argues that “along” has a specialized meaning.
Thus, general use dictionaries serve as a useful starting point
for analysis. One such dictionary defines “along” as (1) ‘[b]y
the length; in a line with the length; lengthwise” and (2) “by
the length o f , as distinguished from across.” WEBSTER’S REVISED
UNABRIDGED DICTIONARY (1996). In another, “along” is defined as (1)
“Over the length of” and (2) “On a line or course parallel and
close t o ; continuously beside.” THE AMERICAN HERITAGE DICTIONARY OF THE
ENGLISH LANGUAGE (4th ed. 2000). A third defines “along” as (1)
“through, o n , beside, over, or parallel to the length or
direction o f , from one end to the other of” and (4) “by the
length; lengthwise.” THE RANDOM HOUSE DICTIONARY OF THE ENGLISH LANGUAGE
-10- (2d ed. 1987). In still a fourth, “along” is defined as “in a
line with the length, parallel to the longest dimension or course
(of something understood) . . . .” THE COMPACT EDITION OF THE OXFORD
ENGLISH DICTIONARY (1971). Neither party disputes the validity of
these definitions. Rather, they disagree first over which
definition to invoke, and next over how that definition should
apply in this case.
Although all of the above-cited dictionaries recognize that
“along” generally connotes a lengthwise orientation, the
definitions do not support defendant’s more restrictive
interpretation that a ridge extends along an electrode only to
the extent that it extends lengthwise over the electrode’s
longest surface. An electrode may have many surfaces of varying
lengths that together comprise an electrode that is longer than
it is wide. In such cases, a ridge that extends lengthwise in a
line over the electrode’s entire surface from one end to the
other will extend over multiple surfaces. Some of these surfaces
may be parallel to the electrode’s longest surface and others may
not. Nevertheless, each segment of such a ridge has a lengthwise
orientation with respect to the electrode as a whole regardless
of whether the segment is on or parallel to the electrode’s
-11- longest surface. The dictionaries cited by the defendant in no
way foreclose such an interpretation because they do not require
that the lengthwise orientation must be with respect to an
object’s longest surface rather than the object as a whole.
To further support its position, defendant points to figures
depicting the invention’s preferred embodiment. Although
defendant correctly claims that these figures depict cylindrical
electrodes that have ridges only on their cylindrical side
surfaces, such figures cannot be used to read into the claim a
limitation that it does not contain. See Fuji Photo Film Col,
Ltd. v . International Trade Comm’n, 386 F.3d 1095, 1106 (Fed.
Cir. 2004). Claim 1 is quite clear in stating that the ridges
that comprise the invention must extend along the electrode
rather than along the electrode’s longest side surface. This
usage leaves no room for defendant’s narrower interpretation.
Defendant alternatively argues that the patent’s prosecution
history demonstrates that along means “extending over the side
surface.” This argument is based on the history of the amendment
to the original application that added the phrase “extending
along said electrode” to what ultimately became claim 1 . The
original application included a claim 1 (“original claim 1 ” ) ,
-12- which was ultimately abandoned, and a claim 10 (“original claim
1 0 ” ) , which ultimately became what is now claim 1 . Original
claim 1 provided in pertinent part for “relief means on said side
surface [of the electrode] extending over a portion of said side
surface intermediate said ends so as to provide a path for arcing
. . . .” Original claim 10 initially provided in pertinent part
for an “electrode having at least one ridge formed thereon, said
ridge being located substantially in said arc chamber.” The
examiner rejected both claims based in part on Patent N o .
3,296,410 (the “Hedger Patent”), which describes an “induction
plasma generator that has as one element an electrode with a
barbed projection at one end. In response, the applicants
explained that their claims differed from the Hedger Patent
because they claimed a ridge which, unlike the barb claimed in
the Hedger Patent, provided a “definition of length” and a “path
to direct the arc.” They went on to state that
Since independent claim 1 already recites that the relief means on the side surface is “extending over a portion of said side surface intermediate said ends so as to provide a path for arcing between the electrode . . .” (emphasis added), it is believed that this amended claim defines over the Hedger reference. By this
-13- amendment, dependent claim 10 2 has been amended to recite that the ridge is “extending along said electrode means.”
Pl.’s Response to Oct. 1 6 , 1987 P.T.O. Official Action at 3 .
Defendant argues that this passage demonstrates that the patentee
incorporated original claim 1’s side surface limitation into
original claim 10 when it amended that claim.
I am unpersuaded by the defendant’s argument. The Federal
Circuit has repeatedly warned district courts that “it is
inappropriate to limit a broad definition of a claim term based
on prosecution history that is itself ambiguous.” Mars Inc. v .
H.J. Herz C o . L.P, 377 F.3d 1369, 1377 (Fed. Cir. 2004);
Inverness Med. Switz. GmbH v . Warner, 309 F.3d at 1382. The
prosecution history cited by the defendant does not come close to
providing unambiguous support for its position. I f , as defendant
claims, the applicants intended original claim 10 to include
original claim 1’s side surface limitation, one would expect that
2 Although this reference refers to original claim 10 as a dependant claim, all other references to the claim in the prosecution history refer to the claim as an independent claim. Moreover, the claim does not appear to be a dependant claim because it does not contain, as it must, a “reference to a claim previously set forth.” 35 U.S.C. § 112. Accordingly, I assume for purposes of analysis that original claim 10 was intended to be an independent claim.
-14- the applicants would have explicitly included the side surface
limitation in the amendment to original claim 1 0 . Moreover,
although the applicants’ intentions are not clear, a fair reading
of the above-cited passage suggests that they most likely
intended the amendment merely to emphasize that their invention,
unlike the Hedger Patent, taught a ridge that had a “definition
of length” and therefore provided a path for arcing. In short,
the evidence relied on by defendants is too weak to justify a
reading of “along” that is contrary to its customary meaning.3
Accordingly, I decline to adopt either of defendant’s proposed
interpretations of “along.”
C. “So as to Provide a Path For Arcing Thereby Producing a Longer Wearing Electrode
Two additional questions remain regarding the proper
interpretation of claim 1 . Both concern the phrase “so as to
3 Plaintiff asserts that “along” is synonymous with o n . Thus, from its perspective, the orientation of the ridges is irrelevant. I decline to adopt this proposed construction because I am not satisfied that I must do so to resolve this case. I lack the power to give advisory opinions concerning the meaning that patent terms may have in cases that are not before m e . Accordingly, until it becomes clear that I must either adopt or reject plaintiff’s proposed interpretation to resolve this case, I decline to do s o . It is sufficient at the present time to merely state that defendant’s proposed interpretations are unjustifiably narrow.
-15- provide a path for arcing, thereby producing a longer wearing
electrode.” Plaintiff asks me to construe the phrase “thereby
producing a longer wearing electrode.” Defendant asks me to
construe the phrase “so as to provide a path for arcing.”
Because I conclude that the phrase “thereby producing a longer
wearing electrode” merely describes an expected result of the
invention claimed in the ‘210 patent, I hold that it does not
limit the patent’s scope. On the other hand, because the
plaintiff concedes that the phrase “so as to provide a path for
arcing” is an explicit claim limitation, I accept that conclusion
without undertaking further analysis.
1 . “Thereby producing a longer wearing electrode”
Claim 1 states that ridges shall be formed along an
electrode “thereby producing a longer wearing electrode.”
Plaintiff argues that this phrase does not further limit what is
otherwise claimed under the patent. I agree.
In Texas Instruments v . United States Int’l Trade Comm’n,
the Federal Circuit held that “a ‘whereby’ clause that merely
states the result of a limitation in the claim adds nothing to
the patentability or substance of the claim.” 988 F.2d at 1172
(citing Israel v . Cresswell, 166 F.2d 153, 156 (C.C.P.A. 1948)).
-16- That is because stating the result of an invention in a patent
does not affect its patentability. Israel, 166 F.2d at 156.
In this case, the “thereby” clause, like the “whereby”
clauses in Texas Instruments and Israel, merely states one result
of the ‘210 patent: a longer wearing electrode. I therefore
conclude that the phrase does not limit plaintiff’s patent claims
in any way.
2. Construing “so as to provide a path for arcing”
Claim 1 also states that ridges shall be carved into its
electrode “so as to provide a path for arcing.” Defendant argues
that this phrase should be construed as a functional limitation
on the scope of the subject matter protected by plaintiff’s
patent. Plaintiff concedes this point. I therefore accept this
construction.
IV. CONCLUSION
For the reasons set forth in this Memorandum and Order, I :
(1) adopt the definition of “arc chamber” that is provided in the
specification; (2) reject defendant’s proposed contextual
interpretations of “along”; (3) determine that the phrase
-17- “thereby producing a longer wearing electrode” does not operate
as a claim limitation; and (4) agree that the phrase “so as to
provide a path for arcing” serves as a functional limitation on
the scope of claims.
SO ORDERED.
Paul Barbadoro United States District Judge
December 9, 2004
cc: Peter Cowan, Esq. Thomas Donovan, Esq. Douglas Dozeman, Esq. Stephen Garlock, Esq. Paul Maddock, Esq. Janet Ramsey, Esq. Jacob S . Wharton, Esq.
-18-