Opinion ID: 781499
Heading Depth: 3
Heading Rank: 1

Heading: Claim Construction: Limitation [b]

Text: 55 Both parties agree that limitation [b] of claim 1 of the '772 patent is written as a means-plus-function claim limitation. A means-plus-function limitation recites a function to be performed rather than definite structure or materials for performing that function. Chiuminatta, 145 F.3d at 1307, 46 USPQ2d at 1755. Such a limitation must be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof. 35 U.S.C. § 112, ¶ 6. 56 The first step in analyzing a claim written in means-plus-function form is to identify the claimed function. Chiuminatta, 145 F.3d at 1308, 46 USPQ2d at 1756. The district court determined that limitation [b] recites a means having the function of rotating said wheel. Lockheed, 88 F.Supp.2d at 1100. SSL maintains that the district court improperly broadened the function of limitation [b] by reading out the remaining claim limitations. We agree with SSL. 57 Once a court establishes that a means-plus-function limitation is at issue, it must identify and construe that limitation, thereby determining what the claimed function is, and what structures disclosed in the written description correspond to the means for performing that function. The phrase means for generally invokes 35 U.S.C. § 112, ¶ 6, and is typically followed by the recited function and claim limitations. Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1584, 39 USPQ2d 1783, 1786-87 (Fed.Cir. 1996). In identifying the function of a means-plus-function claim, a claimed function may not be improperly narrowed or limited beyond the scope of the claim language. Micro Chem. Inc. v. Great Plains Chem. Co., 194 F.3d 1250, 1258, 52 USPQ2d 1258, 1263 (Fed.Cir.1999). Conversely, neither may the function be improperly broadened by ignoring the clear limitations contained in the claim language. The function of a means-plus-function claim must be construed to include the limitations contained in the claim language. 58 In this case, the district court erred by improperly broadening the scope of the claimed function by reading out the limitations contained in the claim language. The function of limitation [b] is properly identified as rotating said wheel in accordance with a predetermined rate schedule which varies sinusoidally over the orbit at the orbital frequency of the satellite. The function is properly identified as the language after the means for clause and before the whereby clause, because a whereby clause that merely states the result of the limitations in the claim adds nothing to the substance of the claim. Tex. Instruments Inc. v. United States Int'l Trade Comm'n, 988 F.2d 1165, 1172, 26 USPQ2d 1018, 1023-24 (Fed.Cir. 1993). 59 Having identified the function of limitation [b], we next construe the meaning of the words used to describe the claimed function, using ordinary principles of claim construction. The district court construed the phrase varies sinusoidally to mean a variation in a sine-shaped curve that passes through zero. Lockheed, 88 F.Supp.2d at 1099. In its claim construction order, the district court explained that the rate or speed of the wheel itself must pass through zero. See Lockheed, No. C-95-3530-SI, slip. op. at 8-10. The district court determined that this construction is consistent with the other limitations in the claims themselves regarding the capacity of the transverse momentum wheel to accelerate in one direction, slow to zero, and rotate in the opposite direction. Id. 60 Neither party disputes the district court's construction of this phrase, and we find no fault in the district court's careful analysis. The meaning of the remaining language of limitation [b] is clear from the plain language of the claim and is consistent with the intrinsic evidence. See Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582-83, 39 USPQ2d 1573, 1576-77 (Fed.Cir.1996). The wheel must rotate in accordance with a predetermined rate schedule. According to the written description, the rate schedule is produced by the sine generator and is dependent on the orbital period as well as the angle of orbital inclination. '772 patent, col. 7, ll. 28-64. It is undisputed that the orbital frequency of the satellite is twenty-four hours; the written description specifically states that the pointing errors change at the orbital frequency, which for a spacecraft in a synchronous altitude orbit, is one day. Id., col. 4, l. 29. Furthermore, it is clear from the written description that the rate schedule is predetermined insomuch as the sine generator produces a sine wave with an amplitude that changes on a continuous basis and that is related to the inclination deviation angle. Id., col. 7, l. 28 — col. 8, l. 33. 61 After identifying the function of the means-plus-function limitation and construing the meaning of the claim language, we look next to the written description to identify the structure corresponding to the function. Micro Chem., 194 F.3d at 1258, 52 USPQ2d at 1263. It is undisputed that the structures disclosed in the '772 patent which correspond to the function of limitation [b] are the sine generator and wheel electronics noted in Figure 4 above. As discussed, the sine generator operates by producing a sine wave signal whose amplitude varies based on the orbital angle of inclination. The wheel electronics are responsive to signals from the sine generator and the tachometer, and generate a signal to the yaw wheel such that the wheel generates a sinusoidal variation of momentum. '772 patent, col. 8, ll. 15-25. 62