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June 25, 1990


The opinion of the court was delivered by: ORRICK


 This is an action for patent infringement involving devices known as nonintrusive Coriolis mass flowmeters, which measure the mass flow rate of fluids. Plaintiff, Micro Motion, Incorporated ("Micro Motion"), is a Colorado corporation with its principal place of business in Boulder, Colorado. Since 1977, Micro Motion has manufactured and sold Coriolis mass flowmeters and accessories. Micro Motion is a wholly-owned subsidiary of Emerson Electric Company. Defendant, Exac Corporation ("Exac"), is a California corporation, incorporated in 1983, with its principal place of business in San Jose, California. In 1983, Exac began the design of a Coriolis mass flowmeter, and, since 1984, Exac's entire business has been the manufacture and sale of Coriolis mass flowmeters and accessories. Exac is a wholly-owned subsidiary of Fisher Controls International, Inc., which in turn is a wholly-owned subsidiary of Monsanto Company.

 Micro Motion filed suit against Exac alleging that Exac's 1100 and 2100 flowmeters *fn1" infringe Claims 8 and 57 of Micro Motion's U.S. Reissue Patent No. 31,450 ("'450 patent") and claim 1 of U.S. Patent No. 4,491,025 ("'025 patent") under the doctrine of equivalents.

 Exac denies that its devices infringe Micro Motion's patents. *fn2" Exac's pleadings initially asserted that the patents in suit were invalid and unenforceable, but these issues have been resolved against Exac, and Exac no longer contests the enforceability or validity of Micro Motion's patents. *fn3"

 This matter was initially tried to a jury between June 30 and July 27, 1987, with Judge Spencer M. Williams presiding. At that trial, Micro Motion alleged both literal infringement and infringement under the doctrine of equivalents. On July 29, 1987, the jury returned a verdict that none of the asserted patent claims had been infringed literally or under the doctrine of equivalents by the Exac meters.

 Micro Motion moved for a new trial. On December 21, 1987, Judge Williams granted the motion and vacated the first jury verdict in its entirety. He also limited the issues on retrial to infringement under the doctrine of equivalents because Micro Motion had decided to waive the literal infringement issue. Judge Williams subsequently recused himself from the case, and it was reassigned to this Court. The parties filed a stipulated waiver of trial by jury, and the retrial before the Court commenced on March 12, 1990.

 After carefully considering the sufficiency, weight, and credibility of the testimony of the witnesses, their demeanor on the stand, the documentary evidence admitted at trial, and the post-trial submissions of the parties, the Court finds that Micro Motion's patents in suit have been infringed under the doctrine of equivalents. This Opinion and Order comprises the findings of fact and conclusions of law required by Federal Rule of Civil Procedure 52(a).


 Micro Motion is the owner of the '450 reissue patent, entitled "Method and Structure for Flow Measurement." PX 1. *fn4" The Coriolis mass flowmeter of the '450 patent was invented by James Smith, founder and President of Micro Motion. The '450 reissue patent issued on November 29, 1983, on an application for reissue of original U.S. patent 4,187,721 (issued on February 12, 1980). PX 2.

 Micro Motion is also the owner of the '025 patent, entitled "Parallel Path Coriolis Mass Flow Rate Meter." PX 3. The Coriolis mass flowmeters disclosed and claimed in the '025 patent were invented by Mr. Smith and Donald Cage, a Micro Motion engineer. The '025 patent issued on January 1, 1985.

 Before direct mass flowmeters became commercially available, mass flow was measured indirectly with volumetric flowmeters. These meters were able to measure mass flow by utilizing two devices, one to measure fluid volume and one to measure fluid density. Mass flow could then be calculated mathematically from these two measurements. Volumetric flowmeters, however, tended to be costly and/or inaccurate, and the two devices required significantly more maintenance than a single meter. RT-WHO 41, 84-86, 126-27, 170, 180-81, 1131, 1138.

 In order to accurately measure mass flow with a single device, Coriolis mass flowmeters were developed. These meters take advantage of a phenomenon known as the Coriolis force. Coriolis forces result when a mass moves radially from one point on a rotating surface to a second point. As the surface rotates, the velocity of the mass changes and the mass is accelerated in a direction perpendicular to its radial path. The acceleration of the mass generates a Coriolis force, which acts on the mass in the surface created by the rotation and perpendicular to the instantaneous radial movement. RT-WHO 249-57; PX 12.

 Coriolis mass flowmeters, when inserted in a pipeline, direct fluid through a curved conduit that conducts the fluid away from the pipeline and then back to the pipeline. As the fluid is conducted through the conduit, the conduit is oscillated. RT-WHO 253-54. When the conduit oscillates in one direction, the Coriolis force acts in that direction on the fluid flowing away from the pipeline, and acts in the reverse direction on the fluid flowing back toward the pipeline. This causes the conduit to twist in response to these oppositely-directed forces. RT-WHO 255-57, 259, 271.

 The amount of Coriolis-induced twist for a given angular velocity is proportional to the mass flowing through the oscillating conduit. Therefore, the greater the mass flow rate, the greater the Coriolis-induced twist. By measuring the amount of twist, it is possible to calculate the mass flow rate of the fluid. RT-WHO 258. *fn5"

 The amount of twist caused by the Coriolis force can be measured by positioning sensors on opposite sides of the oscillating conduit, so that the two sensors differentially detect and measure the opposing movements of the conduit as the fluid is flowing. These sensors measure the difference between the time when one side of the conduit passes by a reference point and the time when the trailing side of the conduit passes that same reference point. The movement of each side of the conduit is essentially sinusoidal, and the output from each sensor can therefore be traced in the form of superimposed sine waves representing each side of the conduit. RT-WHO 260. The time difference between the superimposed waves can then be measured. This measurement is generally referred to as "delta t." RT-WHO 261-62. Delta t is proportional to the mass flow rate. RT-WHO 277-78.

 The relationship between Coriolis-induced distortion and mass flow rate was known before any of the devices in suit were invented. For example, Sipin U.S. Patent 3,485,098 ("Sipin '098") predated Micro Motion's patents and includes the general principle of an oscillating mass flowmeter with curved conduits. PX 6; RT-WHO 272, 274-75. Pearson U.S. Patent 2,624,198 ("Pearson '198") and Roth U.S. Patent 2,865,201 ("Roth '201") also predated Micro Motion's patents and claimed to describe nonintrusive mass flowmeters. PX 4, 5; RT-WHO 273-74. The need for the conduit to direct fluid flow out from the pipeline and then back toward it was also known before Micro Motion's patents issued. RT-WHO 278.

 Micro Motion began producing Coriolis mass flowmeters in 1977. RT-WHO 46-48, 58. These early meters (Micro Motion Model B and Model C) were covered by the '450 patent, and contained a single, U-shaped flow tube. The commercial embodiment of the '450 patent used in the Model B meter utilized optical sensors to measure the Coriolis-induced twist. The commercial embodiment of the '450 patent found in the Model C meter retained the U-shaped flow tube but substituted magnetic velocity sensors for the optical sensors. RT-WHO 59-65, 302-03. Both of these commercial embodiments measured delta t at the point where the electrical signal passed through the zero-voltage point at the maximum rate, which occurred in these devices at the midplane of oscillation. RT-WHO 493, 587, 1900-01.

 In 1983, Micro Motion introduced its Model D meter, covered by the '025 patent. This commercial embodiment of the '025 patent contained two parallel U-shaped flow tubes through which the fluid flowing through the pipe was directed. The Model D meters also used two magnet-and-coil velocity sensors, with the magnetic part of the sensor mounted on one conduit and the coil part mounted on the other conduit. PX 3. Like the Model B and C meters, this commercial embodiment measured delta t at the midplane of oscillation.

 The Exac mass flowmeters in suit were designed by Exac's founders, Drs. Erik Dahlin and Alan Young. During the autumn of 1982, Drs. Young and Dahlin discussed the development of a mass flowmeter, and they decided to form a business in order to market such a meter. In March 1983, Dr. Dahlin met with venture capitalists to seek funding for the business. In April 1983, Dr. Dahlin submitted a business plan to these potential investors. At this time, Exac had not yet built a meter. RT-WHO 844-45; PX 20; Case Dep., Vol. I at 5-6, 9-10, 13-14, 59-60; Dahlin Dep., Vol. I at 49-51, 77, 356.

 Prior to 1982, Drs. Young and Dahlin had experience with the Micro Motion C meter while employed by Zikonix. RT-SW 2447-53; PX 20 at 3. In 1982, Dr. Dahlin obtained and studied Micro Motion's '721 patent, later reissued as the '450 patent. In early 1983, Dr. Dahlin obtained and studied another patent, Cox U.S. Patent No. 4,127,028 ("Cox '028"), which depicts a flat loop and a crossover loop and whose text discloses the use of electromagnetic sensors in place of photo-electric sensors in a Coriolis mass flowmeter. RT-SW 2453-54; PX 7.

 In June 1983, Dr. Dahlin asked Mr. Joseph Bottom of Microbio Resources to obtain for him information on the Micro Motion D meter. Mr. Bottom subsequently met with a Micro Motion salesman, who described and demonstrated the Model D meter and sent him information, literature, and drawings of the meter. Mr. Bottom in turn passed this information on to Dr. Dahlin in June 1983. RT-WHO 193-96, 199-200; PX 26. The first sketch by Dr. Dahlin of a Coriolis meter having two tubes with a split parallel flow path was made in mid-July 1983. RT-SW 2500.

 Exac opened for business in July 1983. In mid-July 1983, Dr. Young asked Mr. William Tanner of Sensoray Company to order a Micro Motion C meter, without revealing that Exac was the intended recipient of the meter. RT-WHO 205-09; PX 36, 38. Mr. Tanner placed this order and, in so doing, made several false statements to Micro Motion. RT-WHO 208-13; PX 38, 49. Mr. Tanner received the C meter on August 22, 1983, and delivered it to Exac. RT-WHO 210-11; PX 40, 41.

 In September 1983, Dr. Young asked Mr. Tanner to order a D meter from Micro Motion, again without revealing Exac as the intended recipient of the meter. Young Dep., Vol. I at 392-94; RT-WHO 213-15; PX 43, 45. Mr. Tanner received a Model D meter on December 9, 1983, and delivered it to Exac. RT-WHO 215-16; PX 51, 52. Drs. Dahlin and Young testified that upon receiving the Micro Motion meters, they took the meters apart and studied them. Dahlin Dep., Vol. I at 84-85; Young Dep., Vol. I at 120-21.

 Exac completed its first working model for a helical crossover loop mass flowmeter in late November or early December 1983. RT-WHO 852. Exac began commercially selling these meters approximately one year later. RT-WHO 852.

 Exac contends that its devices differ from the Micro Motion patents in several respects, and that these differences make its meters noninfringing. These asserted differences are listed below, and are discussed in more detail in Section III, infra.

 First, the Exac devices employ two parallel helical crossover loops *fn6" through which fluid is directed, rather than the "U"-shaped conduits used in the Micro Motion meters. RT-WHO 846, 849-50, 866; PX 95. The Exac devices also measure the Coriolis force in terms of "phase angle," which is a combination of frequency and delta t, rather than measuring delta t alone. RT-WHO 884-85, 897, 979-81, 1047; DX RT at 34. The phase angle is measured at the extreme of conduit oscillation, rather than at the midplane. DX RT at 9, 18, 35, 38-41. The Exac devices allegedly enlarge and magnify the Coriolis effect through mechanical amplification. RT-WHO 873-74. Finally, the Exac meters use a microprocessor to correct for the nonlinearity of operation of the meters, whereas Micro Motion's meters accurately measure mass flow without the need for correction by a microprocessor. RT-WHO 891; DX RT at 19, 29. *fn7"


 A. General Legal Principles

 1. The Legal Standard: Function, Way, Result

 Micro Motion waived any claim that Exac's meters literally infringe the '450 or '025 patents. Rather, Micro Motion argues that the Exac meters infringe its patents under the doctrine of equivalents.

 Infringement under the doctrine of equivalents is reached only when there is no literal infringement. Seattle Box Co. v. Industrial Crating & Packing, Inc., 731 F.2d 818, 828, 221 U.S.P.Q. (BNA) 568 (Fed. Cir. 1984). Thus, the literal language of the patent does not define the "metes and bounds" of the claims when determining equivalence. Thomas & Betts Corp. v. Litton Systems, 720 F.2d 1572, 1579, 220 U.S.P.Q. (BNA) 1 (Fed. Cir. 1983).

 The doctrine of equivalents is a judicially-created equitable doctrine designed to prevent an infringer who does not literally infringe an invention from nonetheless "stealing the benefit of an invention." Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605, 608, 70 S. Ct. 854, 94 L. Ed. 1097 (1950) (quoting Royal Typewriter Co. v. Remington Rand, 168 F.2d 691, 692 (2d Cir.), cert. denied, 335 U.S. 825, 79 U.S.P.Q. (BNA) 454, 93 L. Ed. 379, 69 S. Ct. 50 (1948)). It represents an exception to the general rule that a patent's claims define the metes and bounds of patent protection. Texas Instruments, Inc. v. United States Int'l Trade Comm'n, 805 F.2d 1558, 1572, 231 U.S.P.Q. (BNA) 833 (Fed. Cir. 1986). Because it is a relatively narrow exception, it should not be used to defeat the legitimate process of "inventing around" an adversely held patent. Id.

 Under the doctrine of equivalents, infringement may be found if the Exac devices perform substantially the same function as the Micro Motion inventions, in substantially the same way, to obtain substantially the same result. Graver Tank, 339 U.S. at 608 (citing Sanitary Refrigerator Co. v. Winters, 280 U.S. 30, 42, 74 L. Ed. 147, 50 S. Ct. 9 (1929)). If any one of these three elements of equivalence are not present in the accused device, then there is no infringement of that claim. Lear Siegler, Inc. v. Sealy Mattress Co., 873 F.2d 1422, 1425-27, 10 U.S.P.Q.2D (BNA) 1767 (Fed. Cir. 1989). Micro Motion has the burden to prove infringement under this doctrine by a preponderance of the evidence. SRI Int'l v. Matsushita Elec. Corp., 775 F.2d 1107, 1123, 227 U.S.P.Q. (BNA) 577 (Fed. Cir. 1985). *fn8"

 Determination of infringement under this doctrine is a two-step process. First, the literal language of the claims must be construed to determine their meaning and scope. Any definitional questions are to be resolved by reference to the patent specifications, its prosecution history, the prior art, and expert testimony. PX 277, para. 4; RT-WHO 1573-75. Second, the construed claims must be compared with the accused device, to determine whether the accused device includes each element of the claims or its substantial equivalent. Snellman v. Ricoh Co., 862 F.2d 283, 286, 8 U.S.P.Q.2D (BNA) 1996 (Fed. Cir. 1988). There can be no infringement unless each and every claimed element of each asserted claim or its substantial equivalent is present in the accused device. Lemelson v. United States, 752 F.2d 1538, 1550-51, 224 U.S.P.Q. (BNA) 526 (Fed. Cir. 1985). Where the construed claims are different from the accused device, only insubstantial changes between the construed claims and the accused device constitute infringement under this doctrine. Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 934-35, 4 U.S.P.Q.2D (BNA) 1737 (Fed. Cir. 1987) (en banc), cert. denied, 485 U.S. 961, 108 S. Ct. 1226, 99 L. Ed. 2d 426 (1988).

 An equivalent of a claimed invention need not be described in the patent to constitute an infringement. D.M.I., Inc. v. Deere & Co., 755 F.2d 1570, 1574, 225 U.S.P.Q. (BNA) 236 (Fed. Cir. 1985). The trial court may, however, rely on a reference in the patent itself that discloses the accused element as an equivalent to the patented element in determining equivalence. See, e.g., Linde Air Products Co. v. Graver Tank & Mfg. Co., 86 F. Supp. 191, 199 (N.D. Ind. 1947), aff'd in pertinent part, 167 F.2d 531 (7th Cir. 1948), aff'd in pertinent part, 336 U.S. 271, 93 L. Ed. 672, 69 S. Ct. 535 (1949).

 The law does not require proof of bad faith to establish infringement. Wilden Pump & Eng'g Co. v. Pressed & Welded Products Co., 655 F.2d 984, 989 (9th Cir. 1981). Accordingly, even though the accused device may improve on a patented device through good faith design work, the accused device may nonetheless infringe the patented device. The fact that an accused device is an improvement over the claimed invention as a consequence of subsequent developments does not preclude a finding of infringement under the doctrine of equivalents. Ryco, Inc. v. Ag-Bag Corp., 857 F.2d 1418, 1426-27, 8 U.S.P.Q.2D (BNA) 1323 (Fed. Cir. 1988).

 2. Principles of Claim Construction

 Claims are construed in light of the patent's specifications, the prosecution history, the prior art, and the testimony of expert witnesses. Smithkline Diagnostics, Inc. v. Helena Laboratories Corp., 859 F.2d 878, 882, 8 U.S.P.Q.2D (BNA) 1468 (Fed. Cir. 1988). Under the principle of claim differentiation, a broadly written claim cannot be limited by another, more narrowly written claim. Marsh-McBirney, Inc. v. Montedoro-Whitney Corp., 882 F.2d 498, 504, 11 U.S.P.Q.2D (BNA) 1794 (Fed. Cir. 1989). Moreover, a limitation appearing in the specifications, the preferred embodiments, or the commercial embodiments, cannot be read into the patent's claims. Intervet America, Inc. v. Kee-Vet Laboratories, Inc., 887 F.2d 1050, 1053, 12 U.S.P.Q.2D (BNA) 1474 (Fed. Cir. 1989); Laitram Corp. v. Cambridge Wire Cloth Co., 863 F.2d 855, 865 (Fed. Cir. 1988), cert. denied, 490 U.S. 1068, 109 S. Ct. 2069, 104 L. Ed. 2d 634 (1989). The specifications can, however, be used to construe the literal meaning of words in the claims. McGill Inc. v. John Zink Co., 736 F.2d 666, 674, 221 U.S.P.Q. (BNA) 944 (Fed. Cir.), cert. denied, 469 U.S. 1037, 83 L. Ed. 2d 404, 105 S. Ct. 514 (1984).

 3. The Time at Which Equivalence is Determined

 Prior to the commencement of trial, in response to in limine motions filed by the parties, the Court determined that, for purposes of trial, equivalence would be determined as of the date of alleged infringement by Exac. In electing to use the date of alleged infringement as the relevant time period, the Court rejected Exac's argument that equivalence should be determined at the time the patents in suit issued.

 To support its position, Exac relied on two Supreme Court cases, old but never overruled, that state that there can be no infringement if the fact of equivalence of the two devices was not known at the date of the patent. Gould v. Rees, 82 U.S. 187, 194, 15 Wall. 187, 21 L. Ed. 39 (1872); Gill v. Wells, 89 U.S. 1, 28-29, 22 Wall. 1, 22 L. Ed. 699 (1874). Micro Motion, however, cited several recent Federal Circuit cases that hold that equivalence is determined at the time the alleged infringement occurs. See Atlas Powder Co. v. E.I. duPont de Nemours & Co., 750 F.2d 1569, 1581, 224 U.S.P.Q. (BNA) 409 (Fed. Cir. 1984); Texas Instruments, 805 F.2d at ...

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