Northrop Grumman Corp. v. Intel Corp.
| Decision Date | 31 March 2003 |
| Docket Number | No. 02-1024.,No. 02-1182.,02-1024.,02-1182. |
| Citation | 325 F.3d 1346 |
| Parties | NORTHROP GRUMMAN CORPORATION, Plaintiff-Appellant, v. INTEL CORPORATION and Xircom Corporation, Defendants, and 3Com Corporation, Defendant-Cross-Appellant, and D-Link Systems, Inc., Defendant, and The Linksys Group, Inc., Defendant-Appellee. |
| Court | U.S. Court of Appeals — Federal Circuit |
Appeal from the Court of Appeals, Bryson, Circuit Judge.
David G. Wille, Baker Botts L.L.P., of Dallas, Texas, argued for plaintiff-appellant, Northrop Grumman Corporation. With him on the brief were Samara L. Kline, Larry D. Carlson and Robert M. Chiaviello, Jr.
Natu J. Patel, Wang, Madruga & Patel, of Newport Beach, California, argued for defendant-appellee, The Linksys Group, Inc. Of counsel was Jeffrey C.P. Wang, of Newport Beach, California.
Paul H. Berghoff, McDonnell Boehnen Hulbert & Berghoff, of Chicago, Illinois, argued for defendant-cross appellant 3COM Corporation. With him on the brief were Leif R. Sigmond, Jr., Matthew J. Sampson, George I. Lee, Marcus J. Thymian, and Alison J. Baldwin.
Before MAYER, Chief Judge, FRIEDMAN, Senior Circuit Judge, and BRYSON, Circuit Judge.
Northrop Grumman Corporation ("Northrop") is the owner of U.S. Patent No. 4,453,229 ("the '229 patent"), entitled "Bus Interface Unit." The '229 patent issued in 1982. In late 2000, shortly before the patent expired, Northrop filed suit in the United States District Court for the Eastern District of Texas against several defendants, including appellees 3Com Corporation and The Lynksys Group, Inc. (collectively, "3Com"). Northrop's complaint alleged that the defendants had infringed several claims of the '229 patent.
The district court appointed a special master to make a report and recommendations to the court regarding claim construction. After reviewing the patent and evidence submitted by the parties, the special master construed several critical limitations of the claims in suit. Northrop objected to the special master's claim construction in several respects, but stipulated that if the district court adopted the special master's recommendation with regard to three of the claim construction issues, Northrop would not be able to prove infringement.
The district court adopted the special master's claim construction in large part, including the aspects of the special master's claim construction relating to the three issues referred to in Northrop's stipulation. Accordingly, the district court ruled in the defendants' favor on the issue of infringement. The court subsequently entered a final judgment under Rule 54(b) of the Federal Rules of Civil Procedure. Northrop took the present appeal from that judgment. 3Com initially filed a cross-appeal, but now advises us that the cross-appeal is moot in light of the district court's entry of judgment under Rule 54(b).
On appeal, Northrop argues that the district court construed claims 1 and 13 of the patent unduly restrictively. We agree, and we therefore reverse and remand for further proceedings.
A computer network consists of a set of computers that are interconnected for the purpose of data exchange. Computers within a network typically exchange data over a network serial bus, i.e., a wire over which data is transmitted through a network one bit at a time. In order for the data exchange process to function smoothly, it must be monitored and controlled in accordance with a particular data exchange protocol, which is a set of standard signals that can be interpreted by each device that is connected to the network serial bus.
In the early 1980s, when the '229 patent was issued, communications between a host computer and a serial bus were usually handled by the host computer itself. Under that system, however, valuable host computer processing power was devoted to monitoring and controlling communications over the network serial bus. Ultimately, network designers discovered that they could free up the processing resources of the host computers by incorporating separate devices, known as "bus interface units," between each host computer and the network serial bus.
Bus interface units supervise the exchange of data between a host computer and a network serial bus. The bus interface unit performs two basic tasks: It prepares data internal to a host computer for communication on the network serial bus, and it also receives data from the network serial bus and prepares the received data for processing by an individual host computer. In order for the network to operate efficiently, all the bus interface units on the network must operate in accordance with a particular communications protocol, which governs the method by which the various computers on the network gain access to the network and transfer data over the network serial bus.
At the time the '229 patent was issued, a leading network communications protocol was military standard 1553 ("MIL-STD-1553"). The bus protocol specified by MIL-STD-1553 uses a technique called "time division command/response multiplexing" to share the serial bus. A system employing a "command/response" protocol designates one terminal on the network as the "bus controller" and the other terminals on the network as "remote terminals." The bus controller manages communications on the serial bus by initiating commands and controlling access to the bus, while the remote terminals respond in a predetermined manner to commands from the bus controller. The remote terminals use the bus only in response to commands from the bus controller.
One object of the '229 patent was to transfer the tasks of monitoring and controlling data transfer over the network serial bus to the bus interface unit, thereby freeing the associated processing unit from the need to perform those tasks. Another object of the invention was to enable the bus interface unit to handle a wide variety of flexible bus communication message formats and data algorithms. A third object was to provide a bus interface unit capable of being operated in either a bus controller or remote terminal mode, and thus allow the same bus interface unit to be used as either a bus controller or a remote terminal, depending on the needs of the network at the time.
The accused devices in this case do not use a command/response protocol such as MIL-STD-1553. 3Com contends that the '229 patent does not cover its devices because the patent's scope is limited to devices used in command/response protocol systems, i.e., systems featuring a bus controller and remote terminals. Northrop, on the other hand, argues that its patent is not limited to command/response protocols but is applicable to a wide range of protocols using bus interface units.
The dispute between the parties focuses on two claims of the '229 patent, claims 1 and 13. Those claims provide:
1. In a multiplex data bus interface unit having a Manchester encoder/decoder providing an interface for transmit and receive shift registers to a biphase serial bus, buffer registers providing an interface for the shift registers with an internal parallel bus communicating with a parallel direct memory access data port through a bidirectional buffer, and at least one additional register responsive to the internal bus, the inmprovement [sic] comprising:
means for defining a functional state of the bus interface unit;
means for monitoring a plurality of logical signals characterizing the operational status of the bus interface unit, the monitoring means generating a plurality of control signals regulating a data transfer process between the biphase serial bus and the parallel direct memory access data port.
* * * * *
13. A bus interface unit comprising:
a receive shift register for receiving an incoming data stream from a biphase serial bus;
a transmit shift register for transmitting an outgoing data stream to the biphase serial bus;
a Manchester encoder/decoder for providing an interface for the transmit and receive shift registers to the biphase serial bus;
an internal parallel bus;
a receive buffer for providing an interface for the receive shift register to the internal parallel bus;
a transmit buffer for providing an interface for the transmit shift register to the internal parallel bus;
means for defining a functional state of the bus interface unit; and
means for monitoring a plurality of logical signals characterizing the operational status of the bus interface unit, the monitoring means generating a plurality of control signals regulating a data transfer process between the biphase serial bus and the internal parallel bus.
For present purposes, the most important limitations in claims 1 and 13 are the "means for monitoring" limitation and the "means for defining" limitation, which are found, in essentially identical form, in each of the two claims. Northrop argues that the special master, and thus the district court, erroneously construed those two limitations, as well as the term "bus interface unit," by interpreting each of them as limited to devices employing a command/response protocol. Because the district court adopted the special master's report and recommendations as to all of the limitations pertinent to this appeal, we refer to the special master's analysis and conclusions as the district court's.
The "means for monitoring" limitation is written in means-plus-function form, as permitted by 35 U.S.C. § 112, paragraph 6. Section 112, paragraph 6, allows a patentee to express a claim limitation by reciting a function to be performed rather than by reciting structure or materials for performing that function. Such a limitation is construed "to cover the corresponding structure, materials, or acts described in the specification and equivalents thereof." 35 U.S.C. § 112, para. 6; Chiuminatta Concrete Concepts, Inc. v. Cardinal Indus., Inc., 145 F.3d 1303, 1307-08, 46 USPQ2d 1752, 1755 (Fed.Cir.1998).
In construing a means-plus-function...
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