Kahn v. General Motors Corp., 97-1277

• Decision Date: 03 February 1998
• Docket Number: No. 97-1277,97-1277
• Citation: 45 USPQ2d 1608,135 F.3d 1472
• Parties: Leonard R. KAHN, Plaintiff-Appellant, v. GENERAL MOTORS CORPORATION, Defendant-Appellee.
• Court: U.S. Court of Appeals — Federal Circuit

Page 1472

135 F.3d 1472

45 U.S.P.Q.2d 1608

Leonard R. KAHN, Plaintiff-Appellant, v. GENERAL MOTORS CORPORATION, Defendant-Appellee.

No. 97-1277.

United States Court of Appeals, Federal Circuit.

Feb. 3, 1998.

Rehearing Denied; Suggestion for Rehearing In Banc

Declined March 26, 1998.

Leonard R. Kahn, New York City, argued, pro se.

Linda S. Resh, Kirkland & Ellis, Chicago, IL, argued, for defendant-appellee. With her on the brief was Robert G. Krupka. Also on the brief was Michael Stolarski, Motorola, Incorporated, Schaumburg, IL.

Before NEWMAN, RADER, and GAJARSA, Circuit Judges.

GAJARSA, Circuit Judge.

DECISION

Leonard R. Kahn (Kahn) appeals the judgment of the United States District Court for the Southern District of New York that Claims 53 and 54 of U.S. Patent No. 4,018,994 (the '994 patent) are invalid and not infringed by General Motors Corporation (GM). See Kahn v. General Motors Corp., No. 88-CV-2982, 1997 WL 37581 (S.D.N.Y. Jan.29, 1997). We affirm-in-part and reverse-in-part.

HISTORY OF THE CASE

Kahn filed an action in the United States District Court for the Southern District of New York on April 29, 1988 alleging that GM's AM stereo radio receivers infringed Claims 53 and 54 of the '994 patent. After nine years of litigation and twelve judicial opinions, ¹ including three appeals to this court, ² it appears that this litigation may have finally reached a conclusion. The most recent installment of this case was argued before this court on November 5, 1997.

BACKGROUND ³

A. The '994 Patent

Kahn's patent application was filed May 2, 1975. The '994 patent, entitled "Compatible 53. In a compatible AM stereo receiver of the type for receiving a carrier wave amplitude modulated with a stereo sum (L+R) signal component and phase modulated with a stereo difference (L-R) signal component, and utilizing detection means for deriving the L+R audio signal and demodulating means for deriving the L-R audio signal and means for combining the L+R and L-R signals to isolate the L and R signal outputs, the improvement comprising:

                AM Stereophonic Receivers", subsequently issued on April 19, 1977. 4  The claimed invention addresses the problem of minimizing the distortion within an AM stereo receiver.  The Kahn receiver is designed to receive transmissions in which the two stereo audio signals, the left (L) and right (R) signals, are transmitted by an independent single sideband system.  The information is encoded by envelope or amplitude modulation of the carrier wave by the stereo sum (L+R) signal component.  According to the specification of the '994 patent, the most important feature of this invention is that the receiver derives a distortion cancellation component from the L+R signal and its higher harmonics and uses it to inversely amplitude modulate the stereo difference (L-R) signal.  This substantially reduces the distortion of the L-R signal caused by amplitude modulation of the carrier wave.  This concept is embodied in Claims 53 and 54 of the '994 patent, which read as follows
                

means for deriving a distortion cancellation component from the stereo sum signal component, and

means for combining said distortion cancellation component with a signal including the stereo difference signal component information to substantially reduce distortion of the stereo difference signal component.

54. A receiver according to claim 53, wherein said means for deriving the distortion cancellation component comprises means separating a portion of the L+R audio signal, and said means for combining the separated distortion cancellation component with said signal including the stereo difference signal component information comprises means inversely amplitude modulating the modulated carrier wave with such L+R audio signal portion prior to demodulation thereof.

(emphasis added)

B. The Accused Device

Simple quadrature modulation is often used to encode and transmit a stereo signal to compatible quadrature receivers. Quadrature modulation essentially involves the transmission of two AM signals on the same channel. This allows both the "left" speaker signal and the "right" speaker signal to be transmitted together on the same channel. Before transmission, the L+R and L-R signals are phase shifted relative to one another and combined into a single signal, which is then transmitted to a receiver. The receiver is able to decode this combined signal into its components and present a stereo signal at the speakers.

The accused Compatible Quadrature Amplitude Modulated (C-QUAM) device works in a similar manner. The signal created by quadrature amplitude modulation, however, is not compatible with monophonic AM radio receivers, which cannot decode the quadrature modulated signal, but can only detect envelopes. Therefore, at the transmitter, the C-QUAM system first normalizes the signal so that it can be decoded by standard monophonic AM circuitry. To ensure that these monophonic receivers can also properly derive a monophonic signal from the stereo transmission, the C-QUAM system multiplies the L+R and L-R signals by the cosine of the phase angle (cos(G)) between the two signals to make the signal compatible with standard AM radio receivers. This adjusts the envelope of the quadrature signal to make it compatible with standard monophonic AM radio receivers, which can then interpret the signal as a monophonic signal without having to decode the C-QUAM stereo signals. The resulting L+R and L-R signals are also phase shifted relative to one another in the transmitter. The C-QUAM transmission is in effect the hypotenuse of the triangle Kahn claims that the Motorola circuit used in the GM C-QUAM receivers derives a distortion cancellation component from the L+R signal and uses it to inversely modulate the L-R signal to substantially reduce the distortion in the L-R signal as claimed in Claims 53 and 54 of the '994 patent.

created by the (L+R)*cos(G) and (L-R)*cos(G) signal vectors. Upon reception of a quadrature signal by a C-QUAM receiver, the cos(G) signal is recovered by comparing the envelope to a portion of the quadrature signal. The received C-QUAM signal is then divided by cos(G) to restore the L+R and L-R signals to their original form. These stereo signals can then be demodulated and sent to the speakers.

LITERAL INFRINGEMENT

In determining whether there has been infringement, a two step analysis is required. First, the claims must be correctly construed to determine the scope of the claims. Second, the claims must be compared to the accused device. See Markman v. Westview Instruments, Inc., 52 F.3d 967, 976, 34 USPQ2d 1321, 1326 (Fed.Cir.1995) (in banc), aff'd, 517 U.S. 370, 116 S.Ct. 1384, 134 L.Ed.2d 577, 38 USPQ2d 1461 (1996); Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1581-82, 39 USPQ2d 1573, 1576 (Fed.Cir.1996); Hormone Research Found., Inc. v. Genentech, Inc., 904 F.2d 1558, 1562, 15 USPQ2d 1039, 1042 (Fed.Cir.1990). To establish literal infringement, a plaintiff must demonstrate that every limitation in the claim is literally met by the accused device. See Intellicall, Inc. v. Phonometrics, Inc., 952 F.2d 1384, 1388-89, 21 USPQ2d 1383, 1387 (Fed.Cir.1992); see also Key Mfg. Group, Inc. v. Microdot, Inc., 925 F.2d 1444, 1449, 17 USPQ2d 1806, 1810 (Fed.Cir.1991). Demonstration that every limitation of the claim is literally met by the accused device must be shown by a preponderance of the evidence. See Envirotech Corp. v. Al George, Inc., 730 F.2d 753, 758, 221 USPQ 473, 477 (Fed.Cir.1984).

A. Claim Construction

Claim construction is a matter of law and is reviewed by this court de novo. Markman, 52 F.3d at 974. Claim 53, the only independent claim at issue in this appeal, is written in means-plus-function language as permitted by 35 U.S.C. § 112, p6. Claims written in means-plus-function form are interpreted to cover the structure set forth in the specification and its equivalents. See 35 U.S.C. § 112, p6; Intellicall, 952 F.2d at 1388; In re Iwahashi, 888 F.2d 1370, 1375, 12 USPQ2d 1908, 1912 (Fed.Cir.1989). The only claim limitation at issue in this appeal is the limitation in Claim 53, which requires "means for deriving a distortion cancellation component from the stereo sum signal component." The district court found that the parties had stipulated that the proper construction of the term "deriving" was "getting something from something else." Kahn, 1997 WL 37581, at * 5. Kahn does not appeal this finding. We therefore adopt this interpretation of the term "derive".

Unlike the ordinary situation in which claims may not be limited by functions or elements disclosed in the specification, but not included in the claims themselves, in writing a claim in means-plus-function form, a party is limited to the corresponding structure disclosed in the specification and its equivalents. See 35 U.S.C. § 112, p6. A structure disclosed in the specification is only deemed to be "corresponding structure" if the specification clearly links or associates that structure to the function recited in the claim. See B. Braun Med., Inc. v. Abbott Lab., 124 F.3d 1419, 1424, 43 USPQ2d 1896, 1900 (Fed.Cir.1997). The duty to link or associate structure in the specification with the function is the quid pro quo for the convenience of employing § 112, p6. See O.I. Corp. v. Tekmar Co., 115 F.3d 1576, 1583, 42 USPQ2d 1777, 1782 (Fed.Cir.1997).

There is sufficient structure disclosed in the '994 patent associated with the claim limitations. Kahn points to the structure associated with each limitation of Claim 53. Kahn claims that the limitation requiring "means for deriving a distortion cancellation component from the stereo sum signal component" is found in Figures 1, 2 and 3 and is labeled therein as parts 40, 44, 54, 54' and 96'. Kahn also claims that this limitation is disclosed in the specification of the '994 patent at column 5, lines 1 to 13. Turning to the Figures 1, 2 and 3 of the specification of

the '994 patent, the...