(Fed. Cir. 1995). "Claims may not be construed one way in order to obtain their allowance and in a different way against accused infringers." Id. However, "unless altering claim language to escape an examiner rejection, a patent applicant only limits claims during prosecution by clearly disavowing claim coverage." York Products, Inc. v. Central Tractor, 99 F.3d 1568, 1575 (Fed. Cir. 1996).
Kress originally applied for the patent on August 9, 1976. During the prosecution, the Patent Office rejected the application because of similarities between claim one and a number of existing patents, including a British patent. The British patent described a slag pot carrier that used two separate sets of linear actuators in lifting and dumping the slag pot. See Pl. Reply Br. Exh. A. The linear actuators moved the captured pot in two separate arcing motions while performing the carry and dump processes. Id.
In May 1977, Kress's attorneys contested the Patent Office's rejection. In their statement, they noted that the British patent required "two sets of actuators . . . one to initially lift the pot and a second set to perform the tilting function." See Def. Exh. d-4 in support of their joint motion. Claim one of the plaintiff's device differed, they argued, because it used "only a pair of linear actuators which . . . produced three different positions of the cradle." Id.
The Patent Office subsequently allowed Kress's first claim with an amendment relating to the manner in which the primary linear actuators move the pot, rather than the number of actuators needed. Pl. Exh. 1C. However, statements made during the prosecution history are relevant in claim construction regardless whether the claim is modified on the basis of that particular argument. Amhil Enterprises, Ltd. v. Wawa, Inc., 81 F.3d 1554, 1560 (Fed. Cir. 1996).
Defendants argue that Kress's statement to the Patent Office limits the coverage of the first claim of plaintiff's patent to carriers with "only one" pair of linear actuators that lift the pot to the second and third positions. We agree.
Kress argues that claim one cannot be limited in this manner because of the wording of claim three. Claim three is dependent on claim one, insofar that it can be applied only in combination with claim one. The scope of an independent claim must be construed to allow for the application of all dependent claims in the patent. Laitram Corp. v. NEC Corp., 62 F.3d 1388, 1393 (Fed. Cir. 1995). Plaintiff argues that because claim three calls for the addition of a secondary pair of linear actuators, claim one cannot be limited to allow for only one pair. We agree. However, as rehearsed, the specification limits the patent as a whole to one pair of actuators that perform the lifting function. Therefore, plaintiff cannot claim that carriers with more than one set of actuators that perform the lifting function infringe its patent.
In sum, based on the language of the claims, specification and the prosecution history, we find that the coverage of the '658 patent is limited to carriers that use "only a pair of linear actuators which produce three different positions of the cradle."
In an attempt to show infringement, Kress has provided a series of photographs of the accused carriers alongside the text and drawings from the patent. See Pl. Exh. 15, 24, 25, 28. As viewed through these exhibits, defendant's carriers appear similar to the patent's schematic drawings, and seem to contain all the component parts listed in the patent.
Defendants argue, however, that their products do not infringe because they require two pairs of linear actuators to lift the slag pot from the ground, whereas plaintiff's patent coverage is limited to those that use only one pair to perform the lifting function.
Of the four accused carriers, Liftking built two for Darlington Steel Co., and the Alexander companies built two for Washington Steel Co. These carriers differ concerning the ability of the secondary actuators.
Defendants have submitted a sworn declaration from Peter McFarlane, Liftking's senior design engineer. In his affidavit, McFarlane states that the secondary linear actuators on the Liftking carriers "perform all the work of lifting a slag pot from the ground to the carry position." Decl. of Peter McFarlane at 3-4. He further states that if only the main actuators were used to lift the slag pot, the Darlington carriers "could not lift, carry or dump" a full slag pot. Id. at 4.
Defendants have submitted a similar declaration from John R. Burkert, the resident equipment designer for Alexander Mil Services, Inc. In his declaration, Burkert states that he originally designed the Alexander carriers with only one set of linear actuators. Decl. of John R. Burkert at 3. However, due to a miscalculation, the one pair could not lift full slag pots. Id. He subsequently added the second set, before having safety engineers test the pots. Id.
Kress argues that the addition to the Alexander carriers was not necessary because that they could lift some pots weighing 46,000 pounds (23 tons) without the additional actuators. However, plaintiff does not dispute that the carriers were not sold or put into use until the additional pair of actuators were installed on the carriers. Further, plaintiff does not dispute that the carriers would not have been satisfactory to the Alexander companies' customers without the additional actuators. We therefore find that both the Liftking and the Alexander companies' slag pot carriers require more than one set of linear actuators to lift the cradle from the horizontal position to the second position.
Because we find that defendants' carriers require a second set of linear actuators to perform the lifting function, Kress's claim of literal infringement fails. Literal infringement requires that the accused device "contain every limitation of the asserted claim." Maxwell, 86 F.3d at 1105. As stated, plaintiff's patent is limited by statements made in the prosecution history to carriers that use "only a pair of linear actuators which produce three different positions of the cradle." Because defendants' carriers require two linear actuators to perform this function, they do not literally infringe.
The same conclusion obtains with respect to our analysis of the patent specification. "When an accused infringer practices disclosed but unclaimed subject matter," this also precludes a finding of literal infringement. Maxwell, 86 F.3d at 1107. As stated above, the patent discloses, but does not claim, the subject matter concerning the ability of the secondary actuators from claim three in "assisting the main linear actuators in picking the pot off the ground." This subject matter, as stated, is "dedicated to the public" and the use by an accused infringer precludes a finding of literal infringement.
Doctrine of Equivalents Analysis
Under the doctrine of equivalents, a product that does not literally infringe may still be found to infringe if "it performs substantially the same function in substantially the same way to obtain the same result." Southwall Technologies, Inc. v. Cardinal IG Co., 54 F.3d 1570, 1579 (Fed. Cir. 1995)(citing Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605, 94 L. Ed. 1097, 70 S. Ct. 854 (1950)); see Warner-Jenkinson Co., 520 U.S. at 37, 1997 WL 84999, *14. However,
A patentee may not narrowly claim his invention and then, in the course of an infringement suit, argue that the doctrine of equivalents should permit a finding of infringement because the specification discloses the equivalents. Such a result would merely encourage a patent applicant to present a broad disclosure in the specification of the application and file narrow claims, avoiding examination of broader claims that the applicant could have filed consistent with the specification.
Maxwell, 86 F.3d at 1107.
The use of disclosed, but not claimed, subject matter by defendants also precludes a finding of infringement under the doctrine of equivalents. Maxwell, 86 F.3d at 1107 (citing Genentech, Inc. v. Wellcome Found, Ltd., 29 F.3d 1555 (Fed. Cir. 1994)).
As rehearsed, we have found that the patent discloses, but does not claim, the subject matter concerning the ability of the secondary actuators in "assisting the main linear actuators in picking the pot off the ground." Because the accused devices utilize this subject matter, we may not make a finding of infringement under the doctrine of equivalents.
We find, as a matter of law, that Kress's patent is limited by its claims, specification and prosecution history to slag pot carriers that use only one set of linear actuators to lift the slag pot cradle from the ground to a carry position. We further find that defendants' carriers use a second set of linear actuators to lift the cradle to the carry position. Because defendants' carriers function in this manner, they neither literally infringe plaintiff's patent, nor infringe by way of the doctrine of equivalents. An appropriate order will follow granting defendants' motion for summary judgment.
Dated: March 10, 1997
Donald E. Ziegler
AND NOW, this 10th day of March 1997, after consideration of the cross-motion the parties for summary judgment,
IT IS ORDERED that the motion of plaintiff, Kress Corporation, for summary judgment be and hereby is denied.
IT IS FURTHER ORDERED that the motions of defendants, Alexander Services, Inc., Alexander Mill Services, Inc. and third party defendant, Liftking Incorporated, for summary judgment be and hereby are granted.
Donald E. Ziegler