dissenting.
This appeal is from the grant of a preliminary injunction. Although my colleagues on this panel, having vacated the injunction, remand the ease to the district court, they also have pre-judged the issue on remand. By imposing a new rule of law that overrides the facts of equivalency, the panel majority bars liability for infringement by an equivalent device if the equivalent does not possess the unclaimed advantages or functions described in the specification. This new rule of law is contrary to the law of claim interpretation and it is contrary to the precedent of equivalency. It greatly narrows the scope of potential equivalents, and limits the findings available to be made by the trier of fact.
In seeking optimum judicial administration of a judgemade doctrine whose purpose is to prevent fraud upon the patent, this new rule weighs heavily against patentees whose inventions have been copied. Whether continuing judicial withdrawal of the availability of the doctrine of equivalents is in the national interest is a complex question of economic policy and property theory. In Wamer-Jenkinson, however, the Court reaffirmed the viability of the doctrine. Now it is time for this court to lay to rest the tensions that have been resolved, and implement the law as it has been entrusted to us.
A. The “All-Advantages” Rule
The panel majority holds that the advantages mentioned in the specification, although not included in the claims, must' be possessed by the accused device before there can be a finding of infringement by equivalency. This is neither a correct nor a useful rule of law. It directly contradicts the rule of claim construction that bars the importing of limitations into the claims from the specification. It renders the technologic facts of equivalency irrelevant, for it precludes a finding of equivalency whenever the accused device does not possess the unclaimed advantages described in the patent, whatever the actual significance of these unclaimed aspects.
It is entirely contrary to precedent to create this new rule of law that makes irrelevant the evidentiary bases of technologic equivalency. ' Precedent has established a carefully wrought balance between, on the one hand, providing an adequate incentive to innovation and fair protection to the inventor’s property, and on the other hand allowing others to build upon the inventor’s contribution. Precedent implements this balance through the facts found upon comparing function/way/result and the substantiality of the changes. It is incorrect to delimit these findings by imposing new barriers to consideration of the relevant evidence.
B. No “Separate Body of Case Law” Supports the Incorrect “All-Advantages” Rule
The purpose of the doctrine of equivalents is to prevent a form of fraud, as the Supreme Court called it in Graver Tank. Its purpose is to protect inventors from those who would take the invention and by insubstantial change avoid the letter of the claims. Precedent contains a wealth of illustration of the balance of the tension between the notice function of claims and the goal of securing to inventors the earned benefits of their technological contributions. The cases that the panel majority states support its new theory, in fact simply illustrate various classical applications of the doctrine of equivalents. I do not share the majority’s characterization of this precedent as supporting its new rule of law.
For example, Gentry Gallery, Inc. v. Berk-line Corp., 134 F.3d 1473, 1477, 45 USPQ2d 1498, 1501 (Fed.Cir.1998) is a straightforward application of prosecution history estoppel based on a certain Brennan reference, wherein the relevant feature of the accused device was found “indistinguishable from the comparable feature in Brennan.” In the case at bar, there is no issue of prosecution history estoppel. In Tanabe Seiyaku Co. v. United States Int’l Trade Comm’n, 109 F.3d 726, 731-34, 41 USPQ2d 1976, 1981-83 (Fed.Cir.), cert. denied, — U.S.-, 118 S.Ct. 624, 139 L.Ed.2d 605 (1997), based on extensive ex*1094trinsic evidence the Commission found that a person skilled in the art would not consider the claimed and the substituted solvents interchangeable. In contrast, in the case at bar both sides agreed that the accused Tractech device was completely interchangeable with the patented device. Ekchian v. Home Depot, Inc., 104 F.3d 1299, 1303-4, 41 USPQ2d 1364, 1368 (Fed.Cir.1997), like Gentry, involved routine application of the doctrine of equivalents and prosecution history estoppel, not some “separate” legal approach. In Ekchian the Federal Circuit held that the district court had erroneously read aspects of the preferred embodiment into the claim as limitations. Id. (citing Laitram Corp. v. Cambridge Wire Cloth Co., 863 F.2d 855, 865, 9 USPQ2d 1289, 1299 (Fed.Cir.1988) (“References to a preferred embodiment, such as those often present in a specification, are not claim limitations.”)). Indeed, Ekchian is strong support for the patentee’s position herein that the unclaimed redundancy advantage is not an automatic limitation to equivalency. Maxwell v. J. Baker, Inc., 86 F.3d 1098; 1106, 39 USPQ2d 1001, 1006 (Fed.Cir. 1996), also relied on by the panel majority, is irrelevant to this case. There is no issue raised herein of the accused infringer practicing subject matter that is disclosed but not claimed.
The majority also cites Applied Materials, Inc. v. Advanced Semiconductor Materials Am., Inc., 98 F.3d 1563, 1574, 40 USPQ2d 1481, 1489 (Fed.Cir.1996), cert. denied, — U.S.-, 117 S.Ct. 1822, 137 L.Ed.2d 1030 (1997). In Applied Materials the court interpreted claims wherein the phrase “cold purge process” was employed in the preamble of a Jepson claim, -and held that such usage was a claim limitation when the preamble language “is essential to particularly point out the invention defined by the claims.” Applied Materials says nothing about unclaimed advantages, and does not support the majority’s proposition that any “explicit function” mentioned in the specification, that might be “identified with” a claim limitation, bars application of the doctrine of equivalents if that function is not literally performed by the accused device.
Finally, in Texas Instruments Inc. v. United States Inti Trade Comm’n, 988 F.2d 1165, 1168-69, 26 USPQ2d 1018, 1020-21 (Fed.Cir. 1993), as in Gentry and Ekchian, prosecution history estoppel prevented recovery of clearly surrendered claim scope. In the case at bar there is no issue of surrender or recovery of claim scope. The six cases cited by the panel majority as forming a “separate body of ease law” involve either prosecution history estoppel or an issue of interchangeability or are merely irrelevant. They provide neither precedent nor support for the court’s new, incorrect, “all-advantages” rule.
C. The Zentmyer Invention
All of the elements of the ’015 patent claim were conceded to be literally present in the Traetech device except for the biasing means, which is set forth in clause [5] of Claim 1:
1. A differential mechanism comprising:
output means;
driving means in spaced relationship to said output means;
driven means operably responsive to said driving means for powering said output means;
said driving means having a pair of clutch driving members coaxially disposed with respect to each other and having opposing spaeed-apart surface faces;
biasing means interposed between said driving member surface faces comprising at least a pin in alignment with a spring assembly consisting of two concentric springs bearing against one end of said pin;
said springs and said pin in axial alignment disposed in an elongated passageway jointly provided in each of said pair of clutch drive members;
each of said clutch drive members has inspection and access openings communicating with said passageway so as to expose said springs and said pins respectively; and
*1095said spring passageway is of oblong configuration in transverse cross-section. (Spacing and numbering added.)
The biasing means as claimed comprises a pin aligned with a spring assembly consisting of two concentric springs bearing against the pin. The biasing means of the accused (Powertrax) device also comprises a pin and a spring assembly bearing against the pin. The accused spring assembly, however, instead of having concentric (outer and inner) springs, consists of an outer spring and an inner plug. It was conceded, at least at the preliminary injunction hearing, that the spring/plug assembly performed the same biasing function in the same way as the concentric spring assembly and achieved the same result. There was proffered deposition testimony of witnesses for both sides to the effect that the claimed and the accused spring assemblies were fully interchangeable.
Tracteeh’s Director of Engineering testified that the inner plug served the same role as the inner spring. To the question, “What were the functions of the inner springs, as you viewed them?”, he answered:
There’s only two possible functions. Number one is to fill up a hole, that was my judgment is the reason that it was in. So that pin that was adjacent to the spring would bear against a nice, full flat surface, and the only other possible reason would be to give you more spring force, and I didn’t feel that we needed additional spring force.
He did not mention what the majority now calls the “key back-up function.” Both sides agreed that the “backup” function (the patent does not use this term) of the inner spring was of minor significance. The claims do not include this function. Nonetheless, my colleagues now hold, as a matter of law, that this unclaimed function must be literally present in the accused device, in order to find equivalency.
This new and absolute rule is presented by the majority as rendering irrelevant any evidence of insubstantiality of the differences, or sameness of function/way/result, with reference to the function described in claim clause [5]. This is a marked departure from precedent—a departure with no redeeming benefit if equivalency is to be fairly adjudicated. The importance of a property mentioned in the specification is a fact to be found and weighed. It is improper to foreclose such evidence by ruling that every unclaimed advantage must be present, whatever its relative significance in practice.
The Zentmyer patent describes six “objects” of his invention. The “primary object” is to “provide a means of assembly which simplifies both manufacture and installation of component parts in said differential mechanism.” This object and advantage, it is agreed, is met by the accused device. The other objects are to increase strength and reliability of the joinder of the clutch parts, to permit ready installation without special tools, to provide an access opening in the clutch members and their housing, to impinge the spring assembly directly on the pins instead of on a connecting medium, and to provide an oblong passageway. All of these objects and advantages are realized in the accused device.
In describing the preferred embodiment Zentmyer discusses the advantage of the redundancy of the second spring, although that is not the primary purpose described for the spring assembly. The primary purpose is to interact with the pin and to eliminate the previously-used loose disk; this is fully achieved by the accused spring assembly. The equivalency of the change in the biasing means, whereby the concentric spring structure is replaced with an outer spring/inner plug, must be found on the evidence.
It is not a fair reading of the specification or prosecution history to hold that the patentee made a “specific exclusion” of all spring assemblies lacking the potential redundancy of this preferred embodiment. The patent, in the description of the preferred embodiment, states that should one spring break, “the second spring will bear the load and prevent the broken spring from exiting the assembly.” As I have mentioned, this function was viewed by even the accused infringer as unnecessary. The Tractech Director of Engineering who produced both the initial exact copies of the PowerTrax differential and the later spring/plug modification (after *1096the patent issued) stated that the spring/plug version was just as durable as the concentric spring version. This again contravenes the majority’s insistence that spring backup was a “key” function whose absence negated any possibility of equivalency. This is a factual issue to be weighed, not a legal imperative.
The majority recognizes that this invention is directed to overcoming the problems with the prior art structure containing a separate disk, and the associated difficulties of installation, failure, and replacement. These are the problems that were overcome by Zentmyer in the device described in the ’015 patent. It was not disputed, at the preliminary injunction hearing, that the accused Tractech device overcame the same problems, by using an almost identical structure. By requiring literal presence of the unclaimed backup potential in the substituted assembly the panel majority distorts and pre-judges its remand for findings on the question of equivalency. It is improper to create a new “imprisoning formula,” see Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 609, 70 S.Ct. 854, 856-57, 94 L.Ed. 1097 (1950), whereby absence of a single unclaimed advantage described in the specification is deemed fatal, as a matter of law, to a finding of infringement under the doctrine of equivalents.
It is the claims that define the invention. See 35 U.S.C. § 112/2 (“The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.”); Pandnit Corp. v. Dennison Mfg. Co., 810 F.2d 1561, 1567, 1 USPQ2d 1593, 1603 (Fed.Cir.1987); Bandag, Inc. v. Al Bolser’s Tire Stores, Inc., 750 F.2d 903, 922, 223 USPQ 982, 996 (Fed.Cir.1984). Advantages described in the body of the specification, if not included in the claims, are not per se limitations to the claimed invention. See Applied Materials, 98 F.3d at 1574, 40 USPQ2d at 1489 (only when the inventor’s purpose is included in the claims does the purpose serve as “a limitation of the claimed invention [that] should be met either literally or equivalently in order to satisfy the criteria of infringement”); E.I. du Pont de Nemours & Co. v. Phillips Petroleum Co., 849 F.2d 1430, 1432-34, 7 USPQ2d 1129, 1131-32 (Fed.Cir.1988) (“Where a specification does not require a limitation, that limitation should not be read from the specification into the claims.” (emphasis in original; citations omitted)).
Information in the specification may of course be relevant when finding the facts of equivalency; but the panel majority has posited its “all-advantages” rule as a threshold rule of law. Since it is incorrect to read into the claims any unclaimed advantages described in the specification, it is equally incorrect to hold that any potential equivalent must, as a matter of law, possess these unclaimed advantages. This is directly contrary to the guidance provided in Wamer-Jenkinson:
An analysis of the role played by each element in the context of the specific patent claim will thus inform the inquiry as to whether a substitute element matches the function, way and result of the claimed element, or whether the substitute element plays a role substantially different from the claimed element.
520 U.S. at -, 117. S.Ct. at 1054, 41 USPQ2d at 1875.
The Supreme Court recognized that infringement by equivalency arises only when the accused subject matter is outside the literal reading of the patent claims. See also Wilson Sporting Goods Co. v. Geoffrey & Assoc., 904 F.2d 677, 684, 14 USPQ2d 1942, 1948 (Fed.Cir.1990) (“doctrine of equivalents, by definition, involves going beyond any permissible interpretation of the claim language”). Thus the panel majority errs both in reading all of the advantages of the preferred embodiment into the claims, and in requiring that all advantages, whatever their substance, must be literally present in the accused device before the accused device can be deemed equivalent to what is claimed.
D. The Preliminary Injunction
The purpose of relief pendente lite is to adjust the relationship of the parties during the litigation. Our appellate role is to determine whether the district court abused its discretion in granting the preliminary injunction. H.H. Robertson Co. v. United Steel *1097Deck, Inc., 820 F.2d 384, 387-91, 2 USPQ2d 1926, 1927-30 (Fed.Cir.1987).
The grant of preliminary relief does not require, and the hearing before the district court did not purport to achieve, a full airing of the substantive merits. The panel majority does not discuss the several factors that the district court deemed significant in weighing the balance of harms, the adequacy of monetary damages, the likelihood of success on the merits, and the public interest. For example, at the hearing the patentee explained that inventor Zentmyer, after spending several years in creating, developing, testing, and perfecting his locking differential for the automobile after-market, filed a patent application and started a small business (PowerTrax) to make and sell the device. The superiority and commercial value of his device were immediately recognized, and it was immediately copied by Traetech, a large and established presence in this specialized market. As held in Illinois Tool Works, Inc. v. Grip-Pak, Inc., 906 F.2d 679, 683-84, 15 USPQ2d 1307, 1310 (Fed.Cir. 1990), it is appropriate to consider the size and relative position of the parties and the effect of a preliminary injunction on each. These aspects were argued before the district court.
In determining the likelihood of success on the merits, the district court may have considered that Tracteeh’s engineers had tried, over a long period, and had failed to solve the problem that Zentmyer solved. The court may have considered that Traetech immediately and exactly copied Zentmyer’s device, to its minute measurements. The court may have considered that Tractech’s subsequent change was made upon a few moments of consultation with a patent attorney, while retaining all of Zentmyer’s features and almost all of Zentmyer’s structure. This was strong circumstantial evidence that Tractech’s changes were insubstantial, and would be so shown at trial.
The district court found a sufficient likelihood that the patentee could prove that the accused spring assembly performed substantially the same function in substantially the same way with substantially the same result as the claimed spring assembly and, upon consideration of all the factors, granted the preliminary injunction. See H.H. Robertson, 820 F.2d at 387-91, 2 USPQ2d at 1927-30 (a preliminary injunction is as available in a patent case as in any other). On the proceedings before the district court, the preliminary ruling was supportable. See Sofamor Danek Group v. DePuy-Motech, Inc., 74 F.3d 1216, 1221, 37 USPQ2d 1529, 1532 (Fed. Cir.1996) (at the preliminary injunction stage “neither party was required to prove [its] case in full”).
The panel majority does not review whether there was an abuse of judicial discretion in the grant of the preliminary injunction, although that is the issue of this appeal. The authority cited by the panel majority consists of appeals of final judgments, not rulings pendente lite. E.g., Applied Materials, 98 F.3d 1563, 40 USPQ2d 1481 (Fed.Cir.1996) (appeal of judgment after full bench trial). As stated in Thornburgh v. American College of Obstetricians and Gynecologists, 476 U.S. 747, 757, 106 S.Ct. 2169, 2177, 90 L.Ed.2d 779 (1985), a court of appeals should limit its review of a preliminary injunction to “determining whether the trial court abused its discretion,” unless the only issue is of law.
E. The Remand for Trial
Finding the facts of equivalency requires comparing the patented device with the accused device, element by element. The facts of equivalency are not found by “claim construction,” but by evidence of the accused structure, including evidence of the substantiality of the differences from each element of the claim.
Appellate caution is required lest we deprive the complainant of the opportunity to prove its ease at trial, by having prejudged it on unadmitted evidence and unfound facts. See Wright Med. Tech., Inc. v. Osteonics Corp., 122 F.3d 1440, 1445, 43 USPQ2d 1837, 1841 (Fed.Cir.1997) (“district court must give Wright an opportunity to prove whether Osteonics infringed under the doctrine of equivalents”); Tanabe, 109 F.3d at 731, 41 USPQ2d at 1981 (patentee must prove by preponderance of evidence that every element is found in accused device literally or by an equivalent). The record before us is *1098not a trial record, but a record of attorney argument.1
In essence, the panel majority has distorted on appeal the process of weighing the evidence, a process that should be left for trial. The correct procedure for determining equivalency as to claim clause [5], the biasing means, would be to consider the concentric springs set forth in the claim and the spring/ plug of the accused device, and to determine equivalency on the entire record of similarities and differences in function, way, and result. Instead, the majority pre-selects a non-existent “inner spring limitation,” although the claims do not mention an inner spring but describe the spring assembly as concentric springs. On remand, all of the facts must be available to the trier of fact, without pre-judgment and without exclusions based on the incorrect “all-advantages” rule.
Possibly the panel majority fell into error by confusing claim construction with infringement, for the majority cites Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 39 USPQ2d 1573 (Fed.Cir.1996) for its holding that the written description is “the single best guide to the meaning of a disputed term.” Here there is no term meaning in dispute. The meaning and scope of the claimed spring assembly is clear, and unchallenged. Similarly, the panel majority relies on cases that turn on prosecution history estoppel. However, the rule propounded by the majority is not prosecution history estoppel, but the creation of a new bar to equivalency.
Thus I must, respectfully, dissent.
. The majority provides us with pictures of the devices and the prior art, apparently inviting affirmation of the correctness of its findings. None of these pictures, or what they represent, is in evidence. The majority reports that they appear in the Joint Appendix. I need not belabor that compilation of the joint appendix is a matter of designation, not a concession that everything designated is admitted, correct, or probative. Thus the panel majority states that the pictures it places in this opinion are "depicted by consent of the parties in Exhibits C, A, and O.” These pictures appear to be part of a Tractech attorney document that was included in the appendix by Tractech’s attorney. Inclusion in the appendix is not "consent” to anything.