2. Claim 57 of the '450 Patent
a. Construction of Claim 57
Claim 57 of the '450 patent is a dependent claim that incorporates by reference all of independent Claim 38.
PX 97. Claim 38 describes "a flowmeter" that contains the same elements previously discussed in Section III B 1, supra. The asserted elements of the conduit described in Claim 38 and the resulting infringement analysis under the doctrine of equivalents need not be repeated here because they are identical to that presented in the preceding discussion of Claim 8. RT-WHO 411-12. Accordingly, for the reasons stated above, the Court finds that independent Claim 38 of the '450 patent has been infringed by the Exac devices under the doctrine of equivalents.
Infringement of an independent claim, however, such as Claim 38, does not necessarily mean that claims dependent on that claim are also infringed. Wahpeton Canvas Co. v. Frontier, Inc. 870 F.2d 1546, 1552 n. 9, 10 U.S.P.Q.2D (BNA) 1201 (Fed. Cir. 1989). The Court must, therefore, rule separately on the issue of infringement of Claim 57.
Claim 57 of the '450 patent contains one additional element not present in Claim 8. It requires that the resonant frequency of the patented conduit about its oscillation axis must be lower than the resonant frequency of the conduit about its axis of symmetry.
There was little testimony on this point at trial, and the issue appears to have been essentially conceded by Exac. The evidence that was offered at trial demonstrated that Exac's conduits have an oscillation axis with a lower resonant frequency than that of the deflection axis. RT-WHO 354-55, 1649-50. Thus, the Court finds that this additional element is literally present in the Exac devices.
Given that the one additional element presented by dependent Claim 57 is literally present in the Exac devices, and the remaining elements of Claim 57 (which are expressed in Claim 38 and incorporated by reference) have already been found to be infringed under the doctrine of equivalents, the Court finds that Claim 57 as a whole has been infringed by Exac's devices under the doctrine of equivalents.
3. Claim 1 of the '025 Patent
The '025 patent, issued on January 1, 1985, marked a significant change from the concept of the '450 patent. The '025 patent introduced the design of two parallel flow tubes in place of a single oscillating conduit. Parallel flow tubes were introduced by Micro Motion to correct certain problems that had arisen with the commercial embodiments of the '450 patent. The meters disclosed in the '450 patent, when installed, had been susceptible to external vibrations that affected the accuracy of their mass flow measurement. RT-WHO 343-44.
In the devices covered by the '025 patent, fluid flowing toward the Micro Motion meter is directed through two parallel conduits. PX 89. These conduits are oscillated in opposite directions, so that any effect from external vibration is equal and opposite in the two tubes, thus cancelling out the effects of vibration. Cage Dep. at 79, 81-83, 113-114; RT-WHO 342-43. As a result, the '025 commercial meters could be mounted directly in the fluid line, instead of having to be mounted to a support. RT-WHO 344. Although the '025 patent did not issue until January 1, 1985, Micro Motion began marketing the preferred embodiment of the '025 patent as its Model D meter in December 1982. RT-WHO 90-91. Micro Motion alleges that the Exac parallel tube flowmeters infringe Claim 1 of the '025 patent under the doctrine of equivalents.
a. Construction of Claim 1
Claim 1 of the '025 patent is an independent claim. PX 99. The parties agreed for purposes of this trial that the claim language requires a planar conduit
(RT-WHO 336-37, 418; PX 99), an element that is clearly not literally satisfied by the nonplanar Exac helical crossover conduits.
Claim 1 of the '025 patent is in many respects almost identical to Claims 8 and 57 of the '450 patent, and the claim constructions adopted in sections 1 and 2, above, will be applied where they are relevant to this claim.
Claim 1 contains six elements. First, the claim requires an inlet manifold and an outlet manifold. The Court finds that this element is literally present in the accused Exac devices. RT-WHO 416.
The second element of this claim describes "two U-shaped flow tubes" with certain specified characteristics. With the exception of the requirement that the conduits be planar, the Court finds that all of the characteristics of this second element are literally present in the Exac devices.
In reaching this finding, the Court is aware that the second element of Claim 1 refers to "U-shaped flow tubes" without enclosing the "U" in quotation marks, as was done in the '450 patent. The lack of quotation marks in the '025 patent, however, does not indicate that the '025 patent requires conduits in the shape of a literal "U." This is because the '025 patent itself specifically incorporates the teachings of the '450 patent, which the Court has construed previously to require only a functional "U" shaped conduit. PX 3 at col. 1, 1. 29 -- col. 2, 1. 42. Therefore, because the '025 patent incorporates the '450 patent by reference, Claim 1 of the '025 patent is similarly construed to require that the conduits be in the shape of a functional, not a literal, "U." RT-WHO 619-21. The Exac helical crossover conduits literally meet the requirement of a functional U because they direct the flow of fluid away from the support, then parallel to the support, and then back toward the support. RT-WHO 357-58, 454, 1773-74.
Exac's conduits also literally contain the remaining features described by the second element of Claim 1. Exac's conduits are free of pressure sensitive joints (RT-WHO 417), mounted in parallel fashion and fixedly attached (RT-WHO 417), and cantilevered. RT-WHO 417. The Exac conduits have essentially equal moments of inertia and essentially equal spring constants (RT-WHO 418), and the resonant frequency of the torsion axes is different from the resonant frequency of the bending axes and from the odd harmonic values of the resonant frequency of the bending axes. RT-WHO 418-19. Therefore, the only characteristic of the second element of Claim 1 that is not literally present in the Exac devices is the requirement that the conduits be planar.
The third element of Claim 1 is a "means for inputting to each flow tube . . . essentially equal amounts of fluid from an inlet plenum." The fourth element of Claim 1 requires a similar exit plenum to drain fluid from the flow tubes.
The precise definition of "plenum" was disputed at trial. Exac's experts contended its devices contained a flow-splitter, but did not contain a plenum. RT-WHO 1252.
Exac introduced testimony at trial that the plenums called for by the third and fourth elements of Claim 1 must have symmetrical boundaries and must be large enough to produce essentially equal, uniform fluid pressure. Exac also presented evidence that its flowsplitter has none of these qualities. RT-WHO 1252-55.
The Court, however, rejects Exac's interpretation of Claim 1, because Claims 6 and 7 of the '025 patent, which are dependent from Claim 1, recite these very same limitations. The rule of claim differentiation prohibits the Court from reading limitations from dependent (narrow) claims into an independent (broader) claim because to do so would render the dependent claims redundant. Marsh-McBirney, 882 F.2d at 504. The specifications of the '025 patent, which can properly be considered in claim construction, also contain these same limitations. PX 3, col. 6, 11. 29-58. This limiting language, however, refers only to a preferred embodiment of the patent and, moreover, limitations from a patent's specifications cannot be read into its claims. Intervet America, 887 F.2d at 1053; Laitram Corp., 863 F.2d at 865.
The Court may also consider expert testimony when construing claims. Smithkline Diagnostics, 859 F.2d at 882. Micro Motion introduced expert testimony that, according to Webster's Ninth New Collegiate Dictionary, a plenum is a space that is full of matter. PX 275 at paras. 22-23. Under this definition, however, the Exac flowsplitter is not a literal plenum. The flowsplitter is full of matter, in this case fluid, but it is not clearly a "space," because it resembles a continuation of the pipeline more than a discreet chamber. Because the Court concludes that the Exac flowsplitter is not a literal plenum, the third and fourth elements of Claim 1 must accordingly be analyzed under the doctrine of equivalents.
The fifth element of Claim 1 calls for a means of sinusoidally driving the conduits at their resonant frequency, in a manner similar to the tines of a tuning fork. Exac's meters contain a coil and magnet device that excites the conduits in precisely this fashion. RT-WHO 421. This element, then, is literally present in the Exac devices.
The sixth element of Claim 1 is the "means to measure" element. Micro Motion argued that the claim language does not specify any particular point at which delta t is to be measured. The Court, however, disagrees. The language of Claim 1 requires that delta t be measured at the midplane of oscillation. The claim expressly states that the patented device has a "means to measure the time interval between the passages of the first side legs . . . through the respective midplanes of oscillation, and the passage of the second side legs, caused by Coriolis forced deflection about said torsion axes, to pass through the respective midplanes of oscillation at a later time." PX 3, 99.
Nonetheless, having previously found in its discussion of the '450 patent that the Exac devices measure the equivalent of delta t, and that measurement of delta t at the extreme of oscillation is the equivalent of measuring it at the midplane of oscillation, the Court finds that this sixth element of Claim 1 is present by equivalence in the accused Exac devices.
b. Function, Way, Result of Claim 1
All of the elements of Claim 1 of the '025 patent are literally present in the accused Exac meters, with the exception of the requirements that the conduits be planar, that the devices contain an inlet and an outlet plenum, and that the devices measure delta t at the midplane of oscillation. With respect to the planarity and "means to measure" elements of this claim, however, the Court's previous discussion of the '450 patent established the equivalence of planar and nonplanar conduits, delta t and phase angle, and midplane measurement versus measurement at the extremes of oscillation. Accordingly, the only remaining issue for the Court to resolve as to Claim 1 is whether the Micro Motion plenum is equivalent to the Exac flowsplitter under the doctrine of equivalents.
The Court finds that the Micro Motion plenum and the Exac flowsplitter are equivalents. While the Exac flowsplitter is not a literal plenum, it performs substantially the same function, in substantially the same way, to achieve substantially the same result. RT-WHO 420-21.
The "function" of the plenum in the patented devices is to divide the fluid flowing into the conduits into two essentially equal amounts and to direct that fluid into the parallel flow tubes. The "way" the plenum accomplishes its function is to provide a manifold with one inlet opening and two exit openings. The "result" is an essentially equal flow of fluid through the two conduits, which permits an accurate measurement of mass flow. RT-WHO 420.
The Exac flowsplitter performs the same function in substantially the same way. The evidence at trial indicated that the Exac flowsplitter divides the flow of fluid in the pipeline so that fifty-six percent of the fluid goes through one flowtube and forty-four percent of the fluid goes through the parallel tube. RT-WHO 1251-52; DX RT at 46. The Court finds that this division of flow is "essentially equal," as required by Claim 1 of the '025 patent. PX 275 at para. 24. Exac's founders have admitted that its flowmeters split the fluid flow "in half" (RT-WHO 1030; PX 13 at 7) or "approximately in half." RT-SW 2483. Finally, the evidence at trial established that a person of ordinary skill in the art would have been aware, in January 1985 (the date the '025 patent issued), that the Exac flowsplitter was equivalent to the plenum in the patent. PX 276 at para. 44.
Based upon the above findings of fact and conclusions of law, the Court finds that Micro Motion has established by a preponderance of the evidence that the accused Exac devices infringe Claims 8 and 57 of the '450 patent and Claim 1 of the '025 patent under the doctrine of equivalents. Accordingly,
IT IS HEREBY ORDERED that:
1. The trial in this matter is to reconvene at a date set by the Court in order to determine the amount of damages to be awarded to Micro Motion.
2. A Status Conference will be held on Wednesday, July 11, at 2:00 p.m., at which time the parties will present to the Court a stipulation concerning the trial date, a damages study, and the issues that remain to be tried.