As described in the ’714 patent, petroleum refineries recover valuable products from the heavy residual oil that is a byproduct of the refining process. ’714 patent, col. 1, ll. 20-60. That recovery process is known as “delayed coking.” Id. Delayed coking heats the liquid petroleum residue to very high temperatures and then feeds the heated residue into a “coke drum.” In the drum, cracking and polymerization converts the liquid residue into valuable distillates and solid coke. Id. A typical coke drum might be 120 feet high and 30 feet in diameter with openings at the top and bottom. These openings have large, flanged metal plates known as “heads.” When the drum is full, the operators purge the byproducts and “de-head” the drum. During de-heading, the operators manually remove the top and bottom heads to remove the solid coke. Id. De-heading is both difficult and dangerous. Coke drums are very hot and the heads can weigh four tons. During removal, heated residues and coke can spill out and injure nearby workers. Id. Curtiss-Wright’s ’714 patent claims a system and a method that de-heads the coke drum without manually removing the heads.

On March 1, 2005, Curtiss-Wright sought a preliminary injunction to prevent Velan from launching a new valve at an upcoming industry conference, alleging infringement of claims 14, 33 and 36 of the ’714 patent. Velan’s valves do not include adjustment mechanisms like those disclosed in the ’714 patent. Instead, Velan’s valves include upper dynamic, live loaded seats with internal biasing springs. These springs modulate the pressure on the seat to allow the blind to move. Velan designed its seats to allow replacement of these biasing springs. To change the biasing force in Velan’s dynamic, live loaded seats, an operator must replace these internal biasing springs. Thus, Velan’s system envisions removal of the valves from the coke drum. Preliminary Injunction Order, slip op. at 16-17.

Claim 14 of the ’714 patent recites:

14. A coke drum bottom de-heading system comprising:
    at least one coke drum containing manufactured coke therein, said at least one coke drum having a flanged bottom orifice;
    a de-header valve removably coupled to said coke drum to facilitate the removal of said coke from said at least one coke drum by de-heading said at least one coke drum, said de-header valve comprising:
    a main body having an [sic] flanged orifice therein for removably coupling said de-header valve to said flanged bottom orifice of said coke drum;
    an upper and lower bonnet coupled to said main body;
    an adjustable dynamic, live loaded seat coupled to said main body;
    a static seat coupled to said main body in opposition to said dynamic, live loaded seat; and
    a blind coupled to said main body and actuated by an actuator, said blind capable of moving in a bidirectional manner within said de-header valve between said dynamic, live loaded and static seats to control the opening and closing of said de-header valve, said blind providing a seal between said dynamic, live loaded seat and said static seat, said coke drum is de-headed, thus preparing said coke drum for the removal of said coke, by actuating said blind from a closed, sealed position, to an open position thereby causing said coke that has accumulated on said blind and within said valve to be sheared from said blind.

According to the trial court, the term “adjustable” in claim 14 means that the bias force on the live loaded seat can be changed in a manner that is “not limited by any time, place, manner, or means of adjustment.” Preliminary Injunction Order, slip op. at 16. Based on that construction, the trial court concluded that Curtiss-Wright had shown a reasonable likelihood of success on the merits of its infringement claim. Id., slip op. at 18. The trial court observed that Velan can “adjust” the bias force by replacing the springs in its de-header valve. Id. After further considering irreparable harm, the balance of hardships, and the public interest, the district court granted Curtiss-Wright’s motion for a preliminary injunction. Id., slip op. at 21. Velan appeals.

The trial court’s claim construction followed a logical path. The court first set forth the ordinary meaning of “adjustable”: “capable of making a change to something or capable of being changed.” Preliminary Injunction Order, slip op. at 10. The court then determined that a narrower construction of “adjustable” would be inconsistent with other claims in the ’714 patent, which recite an adjustment mechanism that allows adjustment while the device is in use or operation. Id. at 11-13. In other words, the district court relied on claim differentiation during its claim construction. Finally, the district court explained that any construction of the term “adjustable” that requires the presence of the adjustment mechanism disclosed in the ’714 patent would be an impermissible narrowing of that claim term to the structure of the preferred embodiment.

While logical, this chain of reasoning errs because it places too much emphasis on the ordinary meaning of “adjustable” without adequate grounding of that term within the context of the specification of the ’714 patent. Moreover, to the extent this reasoning relies on claim differentiation, it misapplies that limited tool of claim construction.

This court recently reiterated that the specification is the single best guide to the meaning of a claim term. Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed. Cir. 2005) (en banc) (citing Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996)). In this case, the ‘714 patent’s specification describes the deficiencies of the prior art, including the conventional requirement of removing the entire head unit from the coke drum during de-heading:

[The prior art] assemblies or devices require that the head unit be completely removed from the flange portion of the coke drum after each coking cycle and prior to the purging of the coke from the coke drum. This creates an extreme hazard to workers and provides an inefficient and time consuming procedure.

’714 patent, col. 2, ll. 49-54. The ’714 patent specification further extols this invention for overcoming these deficiencies of the prior art:

Another critical aspect of the present invention is the ability to de-head the coke drum without having to remove the head unit, and to do so at a remote location with little or no manual requirements.

Id. at col. 4, ll. 13-17. The ’714 patent then associates the adjustability of the live loaded seat with that critical aspect of the invention. In other words, the patent stresses that adjustment occurs during operation and without removal of the head unit.

Thus, the specification of the ’714 patent consistently, and without exception, describes adjustment that occurs during operation of the de-header system. The districts court’s construction of “adjustable,” which includes a structure that requires dismantling of the valve to perform the adjustment, finds no support in the overall context of the ’714 patent specification.

Moreover, the district court’s construction of “adjustable” renders that limitation nearly meaningless. This court finds it difficult, if not impossible, to imagine any mechanical device that is not “adjustable,” under the ordinary meaning of that term adopted by the district court. Almost any mechanical device undergoes change (for instance, when dismantled to replace worn parts) when no consideration is given to the “time, place, manner, or means of adjustment.”

In light of the specification, the term “adjustable” means that the dynamic, live loaded seat can be adjusted while the de-heading system of claim 14 is in use.

The claim construction confusion in district court arose from its application of claim differentiation, but in trying to avoid unnecessarily limiting claim scope, went overboard. "[C]laim differentiation “can not broaden claims beyond their correct scope.”"

Thus, without using the formal label, the district court relied on claim differentiation to reach its broad meaning. The district court’s misapplication of that claim construction tool is understandable given the variability of explanations of claim differentiation.

In the most specific sense, “claim differentiation” refers to the presumption that an independent claim should not be construed as requiring a limitation added by a dependent claim. See Nazomi Commc’ns, Inc. v. Arm Holdings, PLC., 403 F.3d 1364, 1370 (Fed. Cir. 2005) (“[C]laim differentiation ‘normally means that limitations stated in dependent claims are not to be read into the independent claim from which they depend.’” (quoting Karlin Techs., Inc. v. Surgical Dynamics, Inc., 177 F.3d 968, 971-72 (Fed. Cir. 1999))); see also Phillips, 415 F.3d at 1314-15 (explaining the presumption without invoking the “claim differentiation” label). Thus, the claim differentiation tool works best in the relationship between independent and dependent claims. See Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 910 (Fed. Cir. 2004) (citing Sunrace Roots Enter. Co. v. SRAM Corp., 336 F.3d 1298, 1302-03 (Fed. Cir. 2003)). Indeed the statute stresses that a dependent claim must add a limitation to those recited in the independent claim. See 35 U.S.C. § 112, ¶ 4 (2000) (“[A] claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed.”) (emphasis added). Thus, reading an additional limitation from a dependent claim into an independent claim would not only make that additional limitation superfluous, it might render the dependent claim invalid.

Beyond the independent/dependent claim scenario, this court has characterized claim differentiation more generally, i.e., as the “presumption that each claim in a patent has a different scope.” Versa Corp. v. Ag-Bag Int’l Ltd., 392 F.3d 1325, 1330 (Fed. Cir. 2004) (quoting Comark Commc’ns, Inc. v. Harris Corp., 156 F.3d 1182, 1187 (Fed. Cir. 1998)). Different claims with different words can, of course, define different subject matter within the ambit of the invention. On the other hand, claim drafters can also use different terms to define the exact same subject matter. Indeed this court has acknowledged that two claims with different terminology can define the exact same subject matter. Tandon Corp. v. U.S. Int’l Trade Comm’n, 831 F.2d 1017, 1023 (Fed. Cir. 1987); Hormone Research Found. v. Genentech, Inc., 904 F.2d 1558, 1567 n.15 (Fed. Cir. 1990) (“It is not unusual that separate claims may define the invention using different terminology, especially where (as here) independent claims are involved.”). In this context, this court has cautioned that “[c]laim differentiation is a guide, not a rigid rule.” Laitram Corp. v. Rexnord, Inc., 939 F.2d 1533, 1538 (Fed. Cir. 1991).

With those precedents in mind, this court observes that two considerations generally govern this claim construction tool when applied to two independent claims: (1) claim differentiation takes on relevance in the context of a claim construction that would render additional, or different, language in another independent claim superfluous; and (2) claim differentiation “can not broaden claims beyond their correct scope.” Fantasy Sports Props. v. Sportsline.com, 287 F.3d 1108, 1115-16 (Fed. Cir. 2002) (quoting Kraft Foods, 203 F.3d at 1236). In this case, both of those considerations weigh against the district court’s construction of “adjustable.”