IMS Tech., Inc. v. Haas Automation, Inc., 2000 U.S. App. LEXIS 5139 (Fed. Cir., Mar. 27, 2000).


Claim construction limitations of a means-plus-function claim apply only to terms within that claim that are part of the means for performing the claimed function while terms separate from the means are construed according to standard claim construction methodology.



IMS Technology, Inc ("IMS") is the assignee of U.S. Patent No. 4.477,745 ("the '754 patent"), which contains both method and apparatus claims. The '754 patent is directed to a numerical control for machine tools that runs a program by reading a series of numerical instructions and converting those instructions into electrical control signals. These signals then direct the operation of the machine tool by guiding its movement along x, y, and z axes. Although the written description accompanying the '754 patent does not specifiy a storage format for the completed control programs, the embodiment disclosed employs a tape cassette transport to store the finished programs.

Haas Automation, Inc. and Gene Francis Haas (collectively "Haas") manufacture and sell machine tools that operate using numerical controls. Some Haas control systems store finished programs on floppy disks, while others use a data port that can be connected to an external storage device. The Haas control systems store control programs in a series of standard codes, such as G-codes or M-codes. The IMS control systems store programs in "data blocks" in which each block corresponds to one operational step of the machine tool.

IMS filed suit against Haas, alleging that Haas's machine tools with numerical controls infringe claims 1 and 7 of IMS's '754 patent. IMS also alleged that Haas's apparatus induced infringement and contributed to infringement of at least claims 1, 7, and 11 of the '754 patent.

The district court granted Haas's motion for summary judgment based upon its interpretation of the claim construction in the '754 patent. IMS appealed parts of the district court's claim construction as well as its summary judgement ruling for Haas. IMS argued that the district court incorrectly construed "interface means" and "data block." The district court construed "interface means" as found in claims 1 and 7, to include a tape cassette transport, the structure disclosed in the written description of the '754 patent. Based on this contruction, the court ruled that Haas's floppy disk drive was not an equivalent structure to the tape cassette transport and thus Haas's apparatus did not literally infringe the '754 patent. The Court also found that the floppy disk drive did not infringe the tape cassette transport under the statutory equivalent of 35 U.S.C.§ 112, paragraph 6. The district court construed the term "data block" as found in claims 1 and 11 as limited to the specific variables and inquiry sequences detailed in the written description of the '754 patent; therefore, the term "data block" did not cover the use of G-codes and M-codes. As a result, the district court held that Haas did not infringe claim 11 either literally or under the doctrine of equivalents.

Haas cross-appealed, arguing that if the Federal Circuit vacated the district court's summary judgment ruling, it should additionally reinterpret aspects of its claim construction. Haas argued that the district court incorrectly construed the term "indicator means" as covering only systems that measure the location of the tool relative to the working surface and erred in using the original claim language to construe the term "feed rate adjust means" rather than using the language as amended during the recent patent reexamination proceedings.



1. Whether the district court properly construed limitations that applied to the apparatus claims under 35 U.S.C. § 112, paragraph 6 to also limit terms in the process claims.

2. Whether the district court's grant of summary judgment of non-infringement was appropriate in light of the corrected claim construction.


1. No. The district court erred by improperly limiting the scope of the claims because 35 U.S.C. § 112, paragraph 6 limits only those terms necessary to perform the disclosed function. All other terms in each additional claim should be construed under standard claim construction methodology.

2. No. Under the proper, broader construction of the claims at issue, there were genuine issues of material fact regarding the equivalency of structures in the disclosed invention and the allegedly infringing apparatus.


Cases Cited by the Court

Other Sources Cited by the Court


State of the Law Before ... IMS Tech.

Evaluation of a patent infringement claim requires a two-step analysis: (1) claim construction to determine the limits of the scope and the meaning of the asserted claims, and (2) comparison of the claims with the allegedly infringing devices or methods to determine whether the latter embody every limitation of the asserted claims. See Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1454 (Fed.Cir. 1998). Because claim construction is a question of law, the standard of review is de novo. See id. at 1456. The second step in determining whether an accused device or method infringes an asserted claim, either literally or under the doctrine of equivalents, is a question of fact, for which the standard of review is clear error. See Insituform Techs., Inc. v. Cat Contracting, Inc., 161 F.3d 688, 692 (Fed.Cir. 1998).

Similarly, patent infringement analysis of a claim drafted pursuant to 35 U.S.C. § 112, paragraph 6, often referred to as "means-plus-function" or "step-plus-function" limitations, involves the same two-step analysis – namely, claim construction and comparison of the accused device or method with the properly construed claims. § 112 paragraph 6 claim construction applies to interpretation of claims that describe a “means for” performing a function without adequate description of the structure, material or acts necessary to perform that function. § 112 paragraph 6 claims are construed by reference to those structures, materials, or acts, and their equivalents, as stated in the written description, that are necessary to perform the described function. For literal infringement of a claim with a § 112, paragraph 6 limitation, comparison of claims with the allegedly infringing device or method begins by determining whether the device or method performs an identical function to the one recited in the claim. See Mas-Hamilton Group v. LaGard, Inc., 156 F.3d 1206, 1211-12 (Fed.Cir. 1998). If the function performed is identical, the next determination is whether the accused device uses the same structure, materials, or acts found in the patent specification, or their equivalents. If the identical function is not performed, literal infringement is not possible.

While the Federal Circuit acknowledges differences between § 112, paragraph 6 and the doctrine of equivalents, the Court has indicated on several occasions that that these two tests are “closely related,” involving “similar analysis of insubstantiality of the differences.” Chiuminatta Concrete Concepts, Inc. v. Cardinal Indus., Inc., 145 F.3d 1303, 1310 (Fed.Cir. 1998); see also Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 28 (1997); Valmont Indus., Inc. v. Reinke Mfg. Co., 983 F.2d 1039, 1043 (Fed.Cir. 1993). Consequently, a reduced version of the tripartite test for the doctrine of equivalents has been applied in the § 112, paragraph 6 context to determine whether the differences are insubstantial. Specifically, the test of whether the "function, way, or result" of the substitute structure is substantially different from that described by the claim limitation is truncated to a comparison of “way” and “result.” See Odetics, Inc. v. Storage Tech. Corp., 185 F.3d 1259, 1267 (Fed.Cir. 1999); see also Dawn Equip. Co. v. Kentucky Farms Inc., 140 F.3d 1009, 1019-20 (Fed.Cir. 1998).

Effect of ... IMS Tech on Current Law

The Federal Circuit reaffirmed its method for proper claim construction and infringement analysis of means-plus-function claims falling under 35 U.S.C. § 112 paragraph 6. Infringement analysis under this statute involves a two part determination: (1) claim construction properly construing the scope and meaning of the claims, and (2) comparison of the construed claims to the accused device to determine if it infringes the asserted claim(s).

The Federal Circuit makes it clear that the claim construction limitations of § 112 paragraph 6, limiting a term to the written description and its equivalents, do not apply to all of the terms in each means-plus-function claim. If a term is not part of the means for performing a function in a particular claim, the term must be construed according to standard claim construction methodology; namely, examination of the claim language, written description, and prosecution history. The Federal Circuit additionally clarifies that the statutory claim construction mandate of § 112 paragraph 6 takes precedence over the judicially created doctrine of claim differentiation, even when strict statutory adherence would result in construing two claims as having a very similar scope.

The Federal Circuit provides a road map for the second inquiry to determine literal infringement of claims properly construed under § 112. The Court promulgates a bifurcated test that requires (1) determination of whether the accused device performs an identical function to that recited in the claim, and (2) a finding whether the accused device performs the identical function through use of the same or similar structure, material, or acts as those found in the written specifications, or their functional equivalents. Noting that determination of statutory equivalence under § 112 is often compared to the judicial doctrine of equivalents, the Federal Circuit, formally adopts the doctrine of equivalents substantial similarity test as the second prong of the § 112 infringement test. Under this test, an accused device is equivalent to the written specification if it performs the claimed function in substantially the same way to achieve substantially the same result.

The court interprets § 112 to indicate that a court need not focus on physical structure when determining equivalency. As a guideline, the Federal Circuit provides that where the claimed function does not depend on any specifically described physical structure, such that many possible structures could perform the function, a court should accept a broad range of equivalents. Alternatively, if the physical structure at issue is critical to proper performance of the stated function, the court should consider only a narrow range of equivalents. In addition, the Federal Circuit provides that substantial similarity may be proven by a showing that one with ordinary skill in the art would recognize such parts as interchangeable for the claimed function of the invention.

Unanswered Questions

To what extent if any does a substantial difference remain between the tests for statutory equivalence under 35 U.S.C. § 112, paragraph 6 and the doctrine of equivalence.

Prepared by:

About us
Send email