LINN, Circuit Judge.
Ron Nystrom (“Nystrom”) appeals from the grant of summary judgment of non-infringement of claims 1-15 and of invalidity of claims 18-20 of his U.S. Patent No. 5,474,831 (“the '831 patent”) and from an order denying sanctions under 28 U.S.C. § 1927, entered by the United States District Court for the Eastern District of Virginia in favor of defendants TREX Company, Inc. and TREX Company, LLC (collectively “TREX”). Nystrom v. TREX Co., Inc., No. 2:01cv905 (E.D.Va. Oct. 25, 2002) (original final judgment); Nystrom v. TREX Co., Inc., No. 2:01cv905 (E.D.Va. Oct. 21, 2003) (amended final judgment). Because the district court erroneously construed certain claim limitations and erred in not properly applying our precedent relating to invalidity, we reverse the district court’s summary judgments of non-infringement and invalidity and remand the case to the district court for further proceedings. Further, because the district court did not abuse its discretion in denying Nystrom’s motion for sanctions under 28 U.S.C. § 1927, we affirm the district court’s disposition of that motion.
I. BACKGROUND
A. The '831 Patent
The '831 patent is directed to construction material for use in flooring surfaces; specifically, boards for use in constructing an exterior floor, such as a deck. '831 patent, col. 1, 11. 6-8. The invention described and claimed in the patent is an exterior wood flooring board shaped to shed water from its upper surface while at the same time providing a surface on which it is comfortable to walk and stand. Id. at col. 2, 11. 8-11. In the Summary of Invention, the patent describes the invention as “a decking board which is shaped to shed water from its upper surface, and which also yields a superior product when cut from a log, reducing the amount of scrap in the outermost boards cut from a log.” Id. at col. 2, 11. 20-24. Figure 2, reproduced below, provides a transverse sectional view of the preferred embodiment of the invention:
[1108]*1108[[Image here]]
Id. at col. 2, 11. 49-50. The embodiment depicted in Figure 2 is described in the '831 patent specification as follows:
The board specifically shown and described herein has generally the size and shape of a so-called 5/4 decking board, with rounded top side edges 11 and 12 each having a radius of curvature r of about one-quarter of an inch. The board 10 differs slightly in width w and thickness t from a standard decking board, however, in that it has a width of only about 5 inches and a thickness of about 1-3/8 inches.
More importantly, the board of the invention has a slightly rounded upper surface 13 that slopes gradually off to either side of the center of the board, defining a convex surface that promotes the running off of water. This surface may have a radius of curvature Rj, for example, of about 24 inches.
Further, in a preferred construction the board also has a complementally shaped concave bottom surface 14 with a radius of curvature R2 of about 24 inches, placed to leave two relatively flat side panels c and d along opposite edges of the board.
The curved top surface has a total fall or drop a from the center to each side edge of about 1/8 of an inch, and the curved bottom surface similarly has a total recess b from the plane of the two side panels to the deepest part at the center of the board of about 1/8 of an inch.
Id. at col. 3, ll. 1-24.
Independent claim 1 contains all of the disputed claim terms, and provides (with the disputed terms highlighted):
1. A board for use in constructing a flooring surface for exterior use, said board having a top surface, a bottom surface and opposite side edges, said top surface being manufactured to have a slightly rounded or curved configuration from a longitudinal center line thereof downwardly toward each side edge, thereby defining a convex top surface which sheds water and at the same time is comfortable to walk on, and said bottom surface having a concave configuration for nesting engagement with the top surface of another board so that a plurality of the boards may be stacked one on top of the other with the stability of [1109]*1109conventional boards having flat top and bottom surfaces.
Id. at col. 4,11.19-30 (emphases added).
Independent claim 18 is representative of the claims for which invalidity is disputed, and provides (with the disputed limitation highlighted):
18. A decking board for use in constructing a flooring surface for exterior use, said board having a convex top surface, a bottom surface and opposite side edges; said convex top surface being manufactured to have a radius of curvature with a slightly rounded or curved configuration extending across the top surface from one side edge to the other, defining a difference in thickness between the longitudinal centerline and the opposite side edges, tvith the ratio of said difference in thickness to the width of the board being about 1:40; and said convex top surface serving to shed water from said board when exposed to weather, and at the same time, when a plurality of said boards are laid in side-by-side relationship, presenting a surface that is comfortable to stand and walk on.
Id. at col. 6, ll. 16-29 (emphasis added).
B. Proceedings Below
Nystrom is the inventor and sole owner of the '831 patent. He is a working carpenter and the owner of a two-truck, two-employee lumberyard. He has been in the business of building exterior decks for twenty-five years. TREX is a manufacturer of exterior decking planks made from composites of wood fibers and recycled plastic. On December 5, 2001, Nystrom filed suit in the Eastern District of Virginia, alleging TREX infringed the '831 patent. TREX counterclaimed, seeking a declaratory judgment of non-infringement, invalidity, and unenforceability, and alleging antitrust violations on the part of Nys-trom, his company, and his attorneys. Nystrom then filed a motion to dismiss the antitrust counterclaims. In response, TREX voluntarily dismissed the antitrust counterclaims, but then filed an amended antitrust counterclaim alleging many of the same antitrust violations against Nystrom alone. Soon after the amended counterclaim was filed, TREX dismissed its amended antitrust counterclaim, prompting Nystrom to move for sanctions on the ground that TREX’s attorneys “multi-plie[d] the proceedings ... unreasonably and vexatiously.” 28 U.S.C. § 1927 (2000). The district court denied the motion for sanctions under § 1927. Nystrom v. TREX Co., Inc., No. 2:01cv905 (E.D.Va. July 2, 2002) (“Sanctions Order ”).
In due course, the district court held a Markman hearing and issued a claim construction ruling concerning three disputed claim terms of the '831 patent. Nystrom v. TREX Co., Inc., No. 2:01cv905 (E.D. Va. Aug 19, 2002) (“Claim Construction Order”). Based on the district court’s claim construction ruling, Nystrom conceded that he could not prove his infringement case against TREX. Therefore, Nystrom asked the district court to enter judgment of non-infringement in favor of TREX and to dismiss TREX’s invalidity and unen-forceability counterclaims without prejudice. TREX then moved for summary judgment of non-infringement and for summary judgment of invalidity of claims 18-20. The district court entered judgment of non-infringement of all claims and deferred ruling on the outstanding motion regarding claims 18-20. Nystrom v. TREX Co., Inc., No. 2:01cv905 (E.D.Va. Sep. 11, 2002). Subsequently, the district court granted TREX’s motion for summary judgment of invalidity of claims 18-20. Nystrom v. TREX Co., Inc., No. 2:01cv905 (E.D.Va. Oct. 17, 2002) (“Invalidity Order”). On October 25, 2002, the district court entered its initial final judg[1110]*1110ment. In that judgment, the invalidity and unenforceability counterclaims regarding claims 1-17 were stayed pending appeal.
Nystrom appealed the claim construction rulings, the grant of summary judgment of non-infringement based thereon, the grant of summary judgment of invalidity of claims 18-20, and the district court’s denial of sanctions to this court. On August 8, 2003, we dismissed Nystrom’s appeal for lack of finality in light of the stayed invalidity and unenforceability counterclaims regarding claims 1-17. Nystrom v. TREX Co., Inc., 339 F.3d 1347 (Fed.Cir.2003). Following the entry by the district court on October 21, 2003 of an Amended Final Judgment nunc pro tunc October 25, 2002 that repeated the previously entered judgments of non-infringement and of invalidity of claims 18-20 and dismissed without prejudice the remainder of TREX’s declaratory judgment counterclaims regarding claims 1-17, we reinstated the appeal. Nystrom v. Trex Co., Inc., 83 Fed.Appx. 321, 322. (Fed.Cir.2003).
We have jurisdiction pursuant to 28 U.S.C. § 1295(a)(1) and address the merits of Nystrom’s appeal in this opinion.
II. DISCUSSION
A. Standard of Review
“We review the grant of summary judgment de novo, drawing all reasonable inferences in favor of the non-moving party.” Teleflex, Inc. v. Ficosa N. Am. Corp., 299 F.3d 1313, 1323 (Fed.Cir.2002) (citing Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 255, 106 S.Ct. 2505, 91 L.Ed.2d 202 (1986)). Summary judgment is only appropriate if there are no genuine issues of material fact and the movant is entitled to judgment as a matter of law. SRI Int'l v. Matsushita Elec. Corp., 775 F.2d 1107, 1116 (Fed.Cir.1985) (en banc).
Claim construction is a question of law reviewed de novo. Ferguson Beauregard v. Mega Sys., Inc., 350 F.3d 1327, 1338 (Fed.Cir.2003). Infringement, whether literal or under the doctrine of equivalents, is a question of fact. Id.
This court reviews a district court’s denial of a motion for sanctions under 28 U.S.C. § 1927 pursuant to the law of the regional circuit. See Phonometrics, Inc. v. Westin Hotel Co., 350 F.3d 1242, 1246 (Fed.Cir.2003). The Fourth Circuit reviews the denial of sanctions pursuant to § 1927 for an abuse of discretion. Chaudhry v. Gallerizzo, 174 F.3d 394, 410 (4th Cir.1999).
B. Claim Construction
Nystrom argues that the district court misconstrued three patent claim limitations: “board,” “manufactured to have,” and “convex top surface.” TREX responds that the district court’s claim constructions were correct.
1. “Board”
The district court construed the word “board” in independent claim 1 to mean a “piece of elongated construction material made from wood cut from a log.” Claim Construction Order, slip op. at 9. The district court found that Nystrom had limited the scope of the claim term “board” by statements in the specification that a board is cut or obtained from a log, id. at 7 (citing '831 patent, col. 2, ll. 22-23; id. col. 2,1. 34), and statements made by Nystrom during prosecution in arguing against an obviousness rejection, id. at 8.
Nystrom argues that “board” in claim 1 is not limited to conventional wood boards that are cut from a log. He argues that the claim language “board” does not contain a description of the material from which the board is composed and the claim [1111]*1111should not be so limited. He contends it was error for the district court to rely on statements in the specification to limit the claim because those statements do not represent a clear disavowal of claim scope. Moreover, Nystrom asserts that there was no disavowal in the prosecution history, because his comment in response to an obviousness rejection was not intended to limit but to establish that the resin 'tiles disclosed in the Yoshida reference were not properly combined with the wood planks of the Zagelmeyer reference in the examiner’s § 103 obviousness rejection.’ Thus, Nystrom argues, the comment was not such a clear and' unambiguous disclaimer as to justify limiting the claim term.
TREX responds that the ordinary meaning of “board” is a piece of sawn lumber. Because the specification only disclosed a board as made of wood and cut from a log, TREX contends that the claim term “board” must be limited to wood boards cut from a log. TREX further argues that Nystrom disclaimed non-wood boards by the statements he made during prosecution in overcoming an obviousness rejection based on Yoshida and Zagelmeyer.
We begin our claim construction analysis with the words of the claim. See Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed.Cir.1996).. In construing claims, the analytical focus must begin and remain centered on the language of the claims themselves. Ferguson Beauregard, 350 F.3d at 1338. “In the' absence of an express intent to impart a novel meaning to claim terms, an inventor’s claim terms take on their ordinary meaning.... [T]he ordinary meaning must be determined from the standpoint of a person of ordinary skill in the relevant art.” Teleflex, 299 F.3d at 1325. The ordinary and customary meaning may be determined by reviewing a variety of sources, including the claims themselves; dictionaries and treatises; and the written description, drawings, and prosecution history. Ferguson Beauregard, 350 F.3d at 1338. The ordinary and customary definition will be overcome if the patentee has acted as his or her own lexicographer in explicitly setting forth a definition of a claim term distinct from its ordinary meaning or 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.” Tex. Digital Sys., Inc. v. Telegenix, Inc., 308 F.3d 1193, 1204 (Fed.Cir.2002).1
While some dictionaries define “board” solely in reference to its material composition, see Webster’s Third International [1112]*1112Dictionary 243 (2002) (defining “board” as “a piece of sawed lumber of little thickness but considerable surface area usu. being rectangular and of a length generally exceeding its width”), not all dictionaries are so constrained. For example, the American Heritage Dictionary of the English Language 203 (4th ed.2000) defines “board” as “1. A long flat slab of sawed lumber; a plank. 2. A flat piece of wood or similarly rigid material adapted for a special use.” These definitions show that the ordinary meaning of the word “board” encompasses both a piece of cut wood or sawn timber and a similarly-shaped item made of a rigid material.2
An examination of the written description and other claims of the '831 patent reveals that Nystrom did not disclaim boards made from materials other than logs. Indeed, in the written description, Nystrom described the invention as “a decking board which is shaped to shed water from its upper surface, and which also yields a superior product when cut from a log ...'831 patent, col. 2, ll. 20-23 (emphasis added). The fact that the written description expressly recognizes that the decking board of the invention is “a superior product when cut from a log ” implicitly recognizes that the decking board of the invention may be made of other rigid materials as well. This is consistent with the ordinary and customary meaning and supports a broader construction than that adopted by the district court. Moreover, the claims of the '831 patent reveal that if Nystrom had intended “board” to include only boards made from wood or cut from a log, he could easily have formulated his claim in such a manner. Claim 16, which is similar to claim 1, covers “[a] wood decking board for use in constructing a flooring surface for exterior use, said decking board having a convex top surface, a bottom surface, opposite side edges, and curved growth rings ....” Id. at col. 5, ll. 32-35 (emphases added). By contrast, claim 1 simply claims a “board,” without restricting the term to a particular material or describing characteristics of wooden boards cut from logs. See id. at col. 4, ll. 19-21 (“A board for use in constructing a flooring surface for exterior use, said board having a top surface, a bottom surface and opposite side edges .... ” (emphases added)).
We also consider the prosecution history, to determine whether the “patentee [1113]*1113intended to deviate from a term’s ordinary and customary meaning or that the paten-tee disclaimed or disavowed subject matter, narrowing the scope of the claim terms.” ACTV, Inc. v. Walt Disney Co., 346 F.3d 1082, 1091 (Fed.Cir.2003). See also Arlington Indus., Inc. v. Bridgeport Fittings, Inc., 345 F.3d 1318, 1328 (Fed. Cir.2003) (“In the course of prosecuting a patent application, a patentee may redefine a claim term .... [or][a]n amendment or argument made in the course of prosecution may also serve as a disclaimer of a particular interpretation of a claim term.”). In successfully overcoming a rejection based on the combination of a reference to Yoshida, which disclosed a plastic tile with curved upper and lower surfaces, and a reference to Zagelmeyer, which disclosed a wood board, Nystrom argued:
ZAGELMEYER ... is not believed to teach the basic premises of applicant’s invention, including either the specially shaped top surface or the shaped bottom surface. YOSIDA [sic] discloses a floor covering tile made from synthetic resin sheets. He laminates his the in a particular way so that it is curved up in the middle and down at all four edges. When laid, his tile rests flat on the supporting surface and does not have either a curved top surface or a curved bottom surface. YOSIDA is clearly not concerned with materials made from wood, and especially an elongate [sic] board for exterior use having a convex top smface when installed that will shed water and at the same time provide a surface that is suitable for supporting furniture and comfortable to walk on. There is no suggestion in this patent of providing space between stacked boards or under boards installed on a support structure for circulation of air to promote uniform drying of the boards. Consequently, it [is, sic] not believed that it would be obvious within the context of 35 U.S.C. § 103 to modify ZA-GELMEYER in view of YOSIDA in order to arrive at the claimed invention.
Amendment rec'd Sept. 30, 1993, at 4 (emphasis added). TREX contends that Nys-trom’s argument disclaimed boards that were not made from wood cut from a log. We read Nystrom’s statement that “YOSI-DA [sic] is clearly not concerned with materials made from wood” not as a disavowal or disclaimer that Nystrom’s claimed invention is limited to wood decking boards, but as an argument against the examiner’s obviousness rejection. Nys-trom argued that because the Yoshida and Zagelmeyer references disclosed inventions made of different materials and were in different arts — respectively, resin floor coverings and wood floor coverings — -there was no reason, motivation, or suggestion to combine the references in a way that rendered the claimed invention obvious. See id. (“Consequently, it [is, sic] not believed that it would be obvious within the context of 35 U.S.C. § 103 to modify ZAGEL-MEYER in view of YOSIDA in order to arrive at the claimed invention.”). Nys-trom’s statement is insufficient to restrict the scope of his claims.
We conclude that the district court erred in its claim construction of the term “board.” Giving the term the full range of its ordinary and customary meaning, consistent with the written description and prosecution history, we construe the word “board” as used in claim 1 and its dependent claims, to mean an elongated, flat piece of wood or other rigid material.
2. “Manufactured To Have”
The district court construed the expression “manufactured to have” as used in claim 1 of the '831 patent to be “a manufacturing process utilizing woodworking techniques.” Claim Construction Order, slip op. at 11. The district court [1114]*1114relied on statements in the '831 patent specification that “the advantages of the invention” were achieved through “cutting or milling and the like.” Id. at 10. The district court found this statement in the specification, combined with its prior construction of the claim term “board” to be “construction material made from wood cut from a log,” to be tantamount to a redefinition of the scope of the claimed manufacturing process. Id. at 11.
Nystrom argues that for many of the same reasons the district court erred in construing the word “board,” the district court’s construction of the phrase “manufactured to have” is also in error. Further, he argues the district court’s reliance on language in the specification mentioning “cutting or milling or the like” impermissi-bly reads a limitation from a preferred embodiment into the claim. TREX responds that the district court properly relied on the reference to “cutting or milling and the like” in restricting “manufactured to have” in all of the claims to solely woodworking techniques. TREX argues that the district court’s construction makes sense because the '831 patent covers only wood materials.
In light of our prior construction of “board” as encompassing materials made not only from wood but from other rigid materials as well, we find no reason to limit the phrase “manufactured to have” in claim 1 to woodworking techniques. The district court itself acknowledged that the “cutting or milling and the like” language in the specification that informed its construction was “an example of the preferred embodiment of the manufacturing process [Nystrom] envisions.” Construction Order, slip op. at 10. See also Arlington Indus., 345 F.3d at 1327 (noting that we have consistently warned against importing limitations from preferred embodiments to restrict the ordinary meaning of a patent claim term). As used in the claim, “manufactured to have” in claim 1 of the '831 patent and the claims dependent therefrom means that the convex top surface is shaped by manufacturing. This claim limitation means exactly what it says, and the district court erred in limiting it to the manufacturing steps used to shape wood.
3. “Convex Top Surface”
The district court construed “convex top surface” to mean “an upper surface with an outward curve that has a ratio of its radius of curvature to width of the board between 4:1 to 6:1.” Claim Construction Order, slip op. at 13. It noted that “the specification does not contain any indication that the term convex top surface is to be assigned a specific range of curvature.” Id. at 12. The district court relied on statements the applicant made in the prosecution history that “the preferred [radius of curvature] ration [sic, ratio] is about 5:1.” Id. at 13.
Nystrom argues that the district court erred by ignoring the ordinary and customary meaning of this claim term, which is “an upper surface with an outward curve,” and by importing additional limitations into this claim term from the specification. He observes that claim 1 does not provide an explicit radius of curvature ratio, and that such radii measurements are recited only in dependent claims 3, 7, and 13. Nystrom also argues that the district court erred in finding that he restricted the term to a specific radius of curvature to overcome a rejection based on the Za-gelmeyer reference. He thus contends it was error for the court to construe “convex top surface” to include a specific radius of curvature ratio. TREX responds that the district court properly held that Nystrom limited his claim to a particular radius of curvature in the range of 4:1 to [1115]*11156:1 to distinguish the invention over the prior art Zagelmeyer reference.
The dictionary definition of the claim term “convex” is “having a surface or boundary that curves or bulges outward, as the exterior of a sphere.” American Heritage Dictionary of the English Language 402 (4th ed.2000). This is consistent with the specification of the '831 patent. See, e.g., '831 patent, col. 3, ll. 10-14 (“More importantly, the board of the invention has a slightly rounded upper surface 13 that slopes gradually off to either side of the center of the board, defining a convex surface that promotes the running off of water. This surface may have a radius of curvature R1; for example, of about 24 inches.”). The district court relied on statements Nystrom made during prosecution to distinguish the Zagelmeyer reference as limiting the expression “convex top surface” to a surface with a radius of curvature in the range of 4:1 to 6:1. Claim Construction Order, slip op. at 12-13. Nystrom stated in a supplemental amendment amending claim 16 of the issued patent (referred to as claim 19 during prosecution):
Applicant then began trying different radiuses of curvature, but some were too shallow and when the board tried it tended not to shed water. Others had too short a radius of curvature and a distinct sensation of an uneven surface. Eventually, by trying a variety of curvatures, applicant discovered that a ratio of radius of curvature to width of the board of about 5:1 produced the desired result, i.e., it shed water and did not produce and uneven sensation to someone standing on it.
Claim 19 [claim 16 in the issued patent] and the claims dependent therefrom (the remaining claims have been previously allowed), are directed to a decking board that has a particular configuration which produces specific results not achieved with any of the prior art.... It should he noted, however, that the ratio of the radius of curvature of a board to its width can vary within certain relatively narrow limits, e.g. from about 1:1 to about 6:1, and still meet the basic objectives of the invention, although the preferred ratio is about 5:1. Anything much outside this range does not provide satisfactory performance and/or is not acceptable to the consumer.
Supplemental Amendment, Sep. 7, 1994, at 2-3 (emphasis added). The district court noted that Nystrom’s statement that “[ajnything much outside this range ... is not acceptable” implied that his statements regarding the radius of curvature ratio applied to the entire patent, and was not intended to apply solely to issued claim 16.
The district court erred in its analysis of the prosecution history. Nystrom’s statements were expressly directed to issued claim 16. There is no indication that Nys-trom intended the term “convex top surface” in all of the pending patent claims to be limited to a specific radius of curvature ratio. The district court ignored the fact that the language of claim 16 at the time Nystrom made the disputed statements included the following claim language expressly providing for a radius of curvature ratio of approximately 5:1: “said top surface having a radius of curvature that is approximately five times as great as the width of the board, thereby defining a smoothly shaped and shallow convex top surface that sheds water.... ” Supplemental Amendment, Sep. 7, 1994, at 1 (emphasis added).
Other statements in the prosecution history support this view. Nystrom points to the examiner’s prior rejection of claims 1, 2, 5, 6, 11 and 12 under 35 U.S.C. § 102(b): [1116]*1116“This rejection is being made over the broad claims since they fail to specify any particular degree for the curve of the board.” Examiner’s Action, Mar. 24, 1994, at 2. The examiner eventually allowed claims 1-14 and 18 because the “prior art fail[ed] to teach both sides of the board with a curved configuration,” not because the invented board specified a particular radius of curvature ratio. Examiner’s Action, Dec. 8, 1994, at 4. The prosecution history did not redefine or disclaim “convex top surface” in claim 1 to be limited to a particular radius of curvature ratio. Accordingly, we hold that the correct construction of the expression “convex top surface” as used in claim 1 is the ordinary and customary meaning of an upper surface that curves or bulges outward, as the exterior of a sphere.
In light of the foregoing revised claim constructions of the claim terms “board,” “manufactured to have,” and “convex top surface” as used in claim 1 of the '831 patent and claims dependent therefrom, the district court’s grant of summary judgment of non-infringement cannot stand and is hereby reversed.
C. Invalidity
The district court granted summary judgment in favor of TREX, holding claims 18-20 of the '831 patent invalid as anticipated in light of the Zagelmeyer reference. The parties principally dispute whether Figure 3 of the Zagelmeyer patent anticipates the following limitation of independent claim 18:
said convex top surface being manufactured to have a radius of curvature with a slightly rounded or curved configuration extending across the top surface from one side edge to the other, defining a difference in thickness between the longitudinal centerline and the opposite side edges, with the ratio of said difference in thickness to the width of the board being about 1:4-0 ....
’831 patent, col. 6, ll. 18-25 (emphasis added). The district court held that boards 2, 3, and 5 depicted in Figure 3 of the Zagel-meyer patent anticipate this limitation by illustrating a board with a convex top having a relevant thickness ratio to the width of the board of 1:39, 1:39, and 1:37, respectively. Invalidity Order, slip op. at 6. The district court found that our precedents in Hockerson-Halberstadt, Inc. v. Avia Group International, Inc., 222 F.3d 951 (Fed.Cir.2000), and In re Wright, 569 F.2d 1124 (CCPA 1977), were not applicable, because it considered the correct inquiry to be whether a person of ordinary skill in the art would use measurements from the Zagelmeyer reference to ascertain the degree of curvature. Invalidity Order, slip op. at 6-7. Finding that a person of skill in the art would take such measurements from the boards depicted in Figure 3 of the Zagelmeyer patent, the district court found claim 18 and the associated dependent claims anticipated. Id. at 7.
Nystrom argues that the district court erred by basing its invalidity determination not on the disclosure of the Zagel-meyer patent itself, but instead from renderings made by a TREX employee of hypothetical boards based on the perspective drawings in the Zagelmeyer patent. He argues this violates our precedent in Hockerson-Halberstadt that “patent drawings do not define the precise proportions of the elements and may not be relied on to show particular sizes if the specification is completely silent on the issue.” Hockerson-Halberstadt, 222 F.3d at 956 (citing In re Wright, 569 F.2d at 1127). Nystrom contends that the district court erred in relying on extrinsic evidence in invalidating the '831 patent. The invalidity data relied on by the district court was generated by a TREX employee who made a [1117]*1117software model of the boards depicted in the perspective drawings of Figure 3 of Zagelmeyer patent, then performed computations on the modeled boards to come up with the allegedly invalidating curvature to width ratio.
TREX responds that the district court correctly found that it had presented evidence that persons of ordinary skill in the art would understand Zagelmeyer to disclose the same dimensions as claims 18-20. TREX submitted declarations that it contended detailed the process by which the boards depicted in the Zagelmeyer reference were modeled and from which the invalidating measurements were taken.
“A party seeking to establish that particular claims are invalid must overcome the presumption of validity in 35 U.S.C. § 282 by clear and convincing evidence.” State Contracting & Eng’g Corp. v. Condotte Am., Inc., 346 F.3d 1057, 1067 (Fed.Cir.2003). A patent is invalid as anticipated if every limitation in a claim is found in a single prior art reference. Teleflex, 299 F.3d at 1335.
The district court erred in not properly applying the principles set forth in our prior precedents that arguments based on drawings not explicitly made to scale in issued patents are unavailing. Hockerson-Halberstadt indicated our disfavor in reading precise proportions into patent drawings which do not expressly provide such proportions:
The '792 patent is devoid of any indication that the proportions of the groove and fins are drawn to scale. [The patent owner’s] argument thus hinges on an inference drawn from certain figures about the quantitative relationship between the respective widths of the groove and fins. Under our precedent, however, it is well established that patent drawings do not define the precise proportions of the elements and may not be relied on to show particular sizes if the specification is completely silent on the issue.
Hockerson-Halberstadt, 222 F.3d at 956 (citing In re Wright, 569 F.2d at 1127). In re Wright similarly noted:
We. disagree with the [PTO]’s conclusion, reached by a comparison of the relative dimensions of appellant’s and [the] Bauer [references]’s drawing figures, that Bauer “clearly points to the use of a chime length of roughly 1/2 to 1 inch for a whiskey barrel.” This ignores the fact that Bauer does not disclose that his drawings are to scale. Absent any written description in the specification of quantitative values, arguments based on measurement of a drawing are of little value.
569 F.2d at 1127.
The . district court’s acceptance of TREX’s invalidity arguments based on models made from drawings contained in the Zagelmeyer patent was incorrect. The basis of the district court’s summary judgment of invalidity was a model that TREX developed based on that reference, and not on drawing dimensions or a written disclosure of dimensions contained directly in the patent itself. Under the principles set forth in our prior cases, the speculative modeling premised on .unstated assumptions in prior art patent drawings cannot be the basis for challenging the validity of claims reciting specific dimensions not disclosed directly in such prior art. Thus, we conclude that the district court erred in granting summary judgment of invalidity based on TREX’s models.
Because the district court erred in determining invalidity based on evidence improperly derived from a patent drawing, we need not address Nystrom’s argument based on the district court’s rejection of Nystrom’s declaration. For the reasons [1118]*1118stated, we reverse the district court’s summary judgment of invalidity of claims 18-20 of the '831 patent as anticipated by Zagelmeyer.
D. Sanctions
Section 1927, in Title 28 of the United States Code, imposes liability on counsel for excessive costs, and provides:
Any attorney or other person admitted to conduct cases in any court of the United States or any Territory thereof who so multiplies the proceedings in any case unreasonably and vexatiously may be required by the court to satisfy personally the excess costs, expenses, and attorneys’ fees reasonably incurred because of such conduct.
28 U.S.C. § 1927 (2000). The Supreme Court has explained that § 1927 “is indifferent to the equities of a dispute and to the values advanced by the substantive law. It is concerned only with limiting the abuse of court processes.” Roadway Express, Inc. v. Piper, 447 U.S. 752, 762, 100 S.Ct. 2455, 65 L.Ed.2d 488 (1980).
Under the law of the Fourth Circuit, the district court’s decision denying of sanctions pursuant to 28 U.S.C. § 1927 is reviewed for an abuse of discretion. Chaudhry, 174 F.3d at 410. “A district court abuses its discretion if its conclusion is guided by erroneous legal principles, or rests upon a clearly erroneous factual finding.” Westberry v. Gislaved Gummi AB, 178 F.3d 257, 261 (4th Cir.1999) (internal citation omitted). An appellate court “is obligated to review the record and reasons offered by the district court and to reverse if the court has a definite and firm conviction that the court below committed a clear error of judgment in the conclusion it reached upon a weighing of the relevant factors.” Id. (internal quotation marks omitted). “[S]ection 1927 also requires a finding of counsel’s bad faith as a precondition to the imposition of fees.” Chaudhry, 174 F.3d at 411 n. 14 (internal quotation marks omitted). The Fourth Circuit has further held “as a matter of law that the filing of a single complaint cannot be held to have multiplied the proceedings unreasonably and vexatiously and therefore that § 1927 cannot be employed to impose sanctions.” DeBauche v. Trani, 191 F.3d 499, 511-12 (4th Cir.1999).
TREX’s counsel originally filed four antitrust counterclaims and a supporting brief in response to Nystrom’s infringement complaint (“the original counterclaims”). TREX voluntarily dismissed these original counterclaims and then filed a second, amended antitrust counterclaim (“amended counterclaim”). TREX’s counsel eventually dropped its original and amended counterclaims. Nystrom sought § 1927 sanctions against TREX. In light of DeBauche v. Trani, 191 F.3d 499, 511-12 (4th Cir.1999), which held as a matter of law that the filing of a single complaint cannot multiply the proceedings unreasonably under § 1927, the district court limited its inquiry to whether TREX’s filing of the amended counterclaim was a basis for sanctions in this case.
Nystrom argues that the district court erred in finding that TREX had pled all of the essential elements of an antitrust counterclaim in its amended counterclaim, because TREX failed to establish that Nystrom posed a dangerous probability of success in monopolizing the relevant market for composite decking. Nystrom argues that when TREX’s counsel filed the amended counterclaim, it “knew as a matter of law” that Nystrom lacked market power in the composite decking market because TREX’s counsel knew both that Nystrom was not a participant in that market and that the '831 patent itself did [1119]*1119not create the required market power in that market. Appellant’s Br. at 61-63.
TREX responds that it had ample evi-dentiary basis for its amended counterclaims, even though it admits its original counterclaims were flawed. TREX asserts that when the flaws in its original counterclaims were pointed out, its counsel immediately admitted the mistake and amended them. TREX argues that its counsel did not act in bad faith and that the district court did not abuse its discretion in denying § 1927 sanctions.
The district court declined to And that TREX acted in bad faith in alleging that Nystrom posed a dangerous probability of success in monopolizing the' relevant market. Sanctions Order, slip op. at 7. Although Nystrom asserted to the district court that he operated solely in the market for milled decking material, TREX asserted that it relied bn several statements by Nystrom during the prosecution of the '831 patent that he intended to monopolize both the milled and composite decking material markets. Id. at 6-7. Stating that it lacked sufficient evidence to limit TREX’s supporting evidence to products only in the milled decking material market, the district court declined to find bad faith on the part of TREX and award § 1927 sanctions. Id. at 7.
Nystrom fails to establish how the district court’s conclusion that it lacked sufficient evidence to find TREX acted in bad faith in filing its amended counterclaim constituted an abuse of discretion. From our review of the statements that TREX relied upon in its amended counterclaim, it is not clear which market Nystrom was referencing when he stated in the prosecution history that “licensing negotiations are presently underway with most major manufacturers and distributors of decking boards,” Prelim. Amendment at 3, and the “product ... has the potential of capturing a significant market share,” Amendment rec’d Sept. 30,1993, at 5. The district court’s finding that these statements were not limited just to the milled decking material market was not clearly erroneous. The district court did not err in declining to find TREX acted in bad faith. Because there was no legal error or clearly erroneous factual finding underlying the district court’s conclusion that Nystrom had failed to present sufficient evidence to justify the imposition of sanctions, see Westberry, 178 F.3d at 261, the court did not abuse its discretion in declining to award § 1927 sanctions.
CONCLUSION
Because the district court erred in its constructions of the claim terms “board,” “manufactured to have,” and “convex top surface,” the district court’s grant of summary judgment of non-infringement of claims 1-15 of the '831 patent is reversed. The district court’s summary judgment of invalidity of claims 18-20 of the '831 patent as anticipated by the Zagelmeyer reference is also reversed. Because the district court did not abuse its discretion, we affirm the district court’s refusal to award sanctions under 28 U.S.C. § 1927 in favor of Nystrom. The case is remanded for further proceedings consistent with this opinion.
AFFIRMED-IN-PART, REVERSED-IN-PART, AND REMANDED.
COSTS
Costs are awarded to Nystrom.