Full opinion text
MEMORANDUM OF DECISION THORNBURG, District Judge. THIS MATTER is before the Court on the parties’ motions for the construction of certain claim language used in U.S. Patent No. 4,751,578 to Reiter, et al. (Reiter ’578), U.S. Patent No. 5,038,211 to Hal-lenbeck (Hallenbeck ’211) and U.S. Patent No. 5,293,357 to Hallenbeck (Hallen-beck ’357)’. I. PROCEDURAL HISTORY In June 2000, SuperGuide Corporation (SuperGuide) brought this action seeking declaratory and injunctive relief against the Defendants for the alleged infringement of the above patents. Each Defendant answered and asserted counterclaims-for a declaration of noninfringement and invalidity. In April 2001, Defendants DirecTV Enterprises, Inc., DirecTV, Inc., DirecTV Operations, Inc. (DirecTV) and Hughes Electronics Corporation (Hughes) obtained permission to implead Gemstar Development Corporation (Gemstar). In the third-party complaint, DirecTV and Hughes also sought a declaration of nonin-fringement and invalidity as well as a declaration of ownership of the patents. Gemstar asserted crossclaims against Su-perGuide for breach of contract and declaratory relief. SuperGuide counterclaimed against Gemstar for a declaration of the field of use reserved in the license agreement between the two. EchoStar then asserted as an affirmative defense the issue of patent misuse by Gemstar. By Memorandum and Decision issued May 7, 2001, the undersigned disqualified SuperGuide’s lead counsel, Roderick Dor-man, from continued representation due to his past representation of Gemstar. Su-perGuide petitioned the Federal Circuit Court of Appeals for a writ of mandamus to compel the undersigned to vacate that ruling. While that petition was pending, the undersigned conducted a two-day hearing pursuant to Markman v. Westview Instruments, Inc., 517 U.S. 370, 116 S.Ct. 1384, 134 L.Ed.2d 577 (1996). On August 13, 2001, the Federal Circuit denied Super-Guide’s petition. While this ruling was under advisement, EchoStar moved the United States District Court for the Northern District of Georgia to transfer this action for consolidation with In re Gemstar Development Corporation Patent Litigation, Multidistrict Litigation Case No. 1274, which involves issues of antitrust violations. The motion was based on EchoStar’s affirmative defense of patent misuse asserted against Gemstar in this action. By Order entered September 6, 2001, the undersigned severed that claim from this action. The Multidistrict Litigation Panel has not yet determined whether to transfer the severed action. Having heard oral argument and considered the numerous filings of the parties, this matter is ripe for disposition. II. FACTUAL BACKGROUND The patents at issue, which are owned by SuperGuide, involve interactive television programming guides. Each of the Defendants manufactures, sells or distributes such guides, which SuperGuide claims infringe its patents. GemStar is the licensee of SuperGuide’s patents and has aggressively marketed them. An interactive programming guide allows a television viewer to select specific programs for viewing or recording. In its earliest and most simplistic form, the guide was nothing more than a listing of programs scheduled for broadcast during a particular time frame which scrolled across the television screen. The viewer selected a program by turning to the channel shown for that program or by clicking on the program with a remote control device. The patents at issue describe later inventions with more sophisticated programming, including the selection of programs due to air at future times and the recording thereof. In order to understand how these inventions work, an understanding of basic television technology is necessary. A television signal is an electrical signal that is created when a video camera captures an image. When a television signal is broadcast, a television receiver picks up and decodes the signal so as to produce pictures on the television screen. A television signal is made up of a series of frames, or still pictures, each one containing an image that varies slightly from the image in the preceding frame. When the frames are displayed by a television in rapid sequence, they create the appearance of smooth, uninterrupted motion to the human eye. A standard American television displays 30 frames per second. Each frame is made up of 525 horizontal lines. Each set of alternating lines forms two fields: odd and even. A television produces pictures on the screen by using an electronic beam to scan the horizontal lines of a frame across the inside surface of the screen from left to right and top to bottom. To eliminate flicker, the beam first scans the lines that constitute the odd field, and then scans the lines that constitute the even field. A standard American television displays 60 fields per second. Ampex Corp. v. Mitsubishi Elec. Corp., 966 F.Supp. 263, 265 (D.Del.1997). In other words, the beam moves from left to right and then from top to bottom scanning the surface of the screen 60 times per second and illuminating phosphors on the inside surface of the television screen. Each illuminated spot is called a pixel, which is an acronym for a picture element. Because it takes some time for the beam to move from its horizontal pattern to the vertical pattern, the beam is turned off during the time it changes position in order to avoid interference with the picture. These times are called blanking intervals, which also are used to transmit certain data not here relevant. Sync pulses are used to synchronize the system. [Images] may be recorded using either analog or digital signals. In an analog recording, [images are] converted into an electrical signal by a device such as a [television camera]. The [camera] generates an electrical signal that varies in proportion to changes in [brightness]. The voltage signal is an analogous replica of the [image] source, thus the name “analog” [signal]. A digital [mechanism] converts the same [image] source into a series of binary numbers, Is and 0s. This digital signal represents the [image] source. A digital signal is not continuous. Rather, it represents a “sampling” of the [image] source at regular, closely spaced intervals. Each sample is analogous to a digital snapshot of the [image] at a particular point in time. If the sampling is done frequently enough, the digital signal can accurately'represent the [image] source. Crystal Semiconductor v. TriTech Microelectronics Int’l, Inc., 246 F.3d 1336, 1343 (Fed.Cir.2001). Thus, an analog signal has its variables represented by continuously measured voltages of other quantities, such as the television picture. The scanned voltages together with the blanking intervals and sync pulses constitute an analog signal called a baseband video signal which cannot be transmitted for any significant distance. Therefore, the base-band video signal is superimposed, or modulated, onto a carrier wave. When that wave is ultimately received in the television, it must be demodulated back to the baseband video signal in order for the television to show the program. In the early 1990’s, technology was developed which allowed the transmission of a digital television signal, a signal in which, as noted above, numbers are expressed as digits based on the binary system. Unlike an analog signal, a digital signal does not transmit a baseband video signal. Instead, it converts the brightness levels in the scanned beam into a digital bit stream which, like an analog signal, also must be transmitted over a carrier wave. The parties agree that in 1985, the filing date of the Reiter ’578 patent, television signals were transmitted from a terrestrial broadcast antenna via analog signals modulated onto a carrier wave. These televisions were capable of receiving only analog signals via carrier waves from a terrestrial antenna and could not receive carrier waves transmitted by a satellite. However, in 1985, television signals were also transmitted by cable networks by the use of cable set-top boxes which converted the cable signal into analog format so that it could be processed by the television. Moreover, analog direct broadcast satellite systems, such as CNN and HBO, existed in 1985 which required satellite dishes and set-top boxes to convert the analog satellite signals into ones which could be displayed on the television. These entities encrypted their signals so that a television without their set-top box could not decode the signal. The set-top box received their encrypted satellite signal and decoded it so that it could be viewed on the television. The signals transmitted from these satellites, commonly called C-band satellites, were analog signals. See, e.g., IPPV Enter. L.L.C. v. Echostar Communications Corp., 106 F.Supp.2d 595, 606 (D.Del.2000) (“[Television broadcasting in the early 1980s was conducted solely in an analog format.... [D]igital television signals were not developed until after the date of invention.”). Thus, the parties have agreed that originally all television signals were analog signals. Nonetheless, in 1985, the technology existed for embedding digital data within an analog signal such as was done for closed captioned television. Again, a decoder was required for conversion of the digital data into analog format which could be processed by the television. However, in 1985 digital cable and satellite systems did not exist. The Defendants and Gemstar claim this technology was developed in 1992 and was first available commercially in 1994. The parties also agree that the analog and digital systems are incompatible. III. PRINCIPLES OF CLAIM CONSTRUCTION Although this action is based on allegations of infringement, there must first be a construction of the claims of the patents at issue to determine the scope of each. Bell Atlantic Network Servs., Inc. v. Covad Communications Group, Inc., 262 F.3d 1258, 1267 (Fed.Cir.2001). This determination, called claim construction, is a question of law for the Court. Mark-man, supra. Once the scope of the claims for each patent has been determined, the jury decides whether the properly construed claims read on the accused device; in other words, infringement is a question of fact for the jury. Bell Atlantic Network, supra. “In construing claims, the analytical focus must begin and remain centered on the language of the claims themselves, for it is that language that the patentee chose to use to ‘particularly point[] out and distinctly claim[] the subject matter which the patentee regards as his invention.’” Interactive Gift Express, Inc. v. Compuserve Inc., 256 F.3d 1323, 1331 (Fed.Cir.2001) (quoting 35 U.S.C. § 112, ¶ 2). “It is well-settled that, in interpreting an asserted claim, the court should look first to the intrinsic evidence of record, i.e., the patent itself, including the claims, the specification and, if in evidence, the prosecution history. Such intrinsic evidence is the most significant source of the legally operative meaning of disputed claim language.” Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed.Cir.1996) (citations omitted). However, not “[a]ll intrinsic evidence is [created] equal.” Interactive Gift Express, supra. First, the claim language is consulted. Id. The claim terms are given their ordinary and accustomed meanings while technical terms are construed as having meanings that a person of ordinary skill in the field of the invention at the time thereof would have given to them. Bell Atlantic Network, supra. If the claim language is clear, the specification is consulted merely to determine if a deviation from that clear language has been specified by the inventor. Interactive Gift Express, supra. “The role of the specification includes presenting a description of the technologic subject matter of the invention, while the role of claims is to point out with particularity the subject matter that is patented.” Netword, L.L.C. v. Centraal Corp., 242 F.3d 1347, 1352 (Fed.Cir.2001). “The construction that stays true to the claim language and [that] most naturally aligns with the patent’s description of the invention will be, in the end, the correct construction.” Renishaw P.L.C. v. Marposs Societa’ per Azioni 158 F.3d 1243, 1250 (Fed.Cir.1998). Where the claim language and specification provide an unambiguous construction, it is unnecessary to consult the prosecution history. Interactive Gift Express, 256 F.3d at 1334. Otherwise, the prosecution history should be consulted to ascertain if the inventor made any express representations in obtaining the patent regarding its scope and the meaning of the claims. Bell Atlantic Network, 262 F.3d at 1268. Only as a last resort should extrinsic evidence be consulted. “In those cases where the public record unambiguously describes the scope of the patented invention, reliance on any extrinsic evidence is improper.” Vitronics, 90 F.3d at 1583. In discussing the claims of the various patents, only those claims for which construction has been requested by the parties will be addressed. IV. CLAIM CONSTRUCTION U.S. PATENT NO. 4,751,578 to REITER, et al. In 1985, a patent application was filed for an invention described as an electronically controllable system for viewing on a television up-dateable television programming information and the patent was issued in 1988. The terms which are in dispute in Claim 1 of Reiter ’578 are set forth in bold font. 1. A system for electronically controll-ably viewing updateable information on a television having a screen comprising: (a) a microcontroller including input/output interfaces, a microprocessor, and an updateable memory comprising at least a RAM, said RAM of said microcontroller being updateable via an electronic medium and storing updated information including at least television programming information; (b) a mixer for mixing a regularly received television signal with the signal generated by the microcon-troller in accord with instructions of said microcontroller; (c) an RF section for receiving instructions from said microcontroller and for receiving radio frequency information from the mixer and a television station and properly converting the information into video signals which may be sent to said television for viewing; and (d) a remote control system, said mi-crocontroller being controllable by said remote control system, for permitting a viewer of said television to direct said microcontroller to perform a search on at least said updated television programming information contained in said RAM of said microcontroller, a subset of at least said updated television programming information being output to said mixer so as to provide on the television screen television programming information desired by the viewer in a desired format. Reiter ’578, at Col. 8,11. 8-38. The first disputed term is “micro-controller.” SuperGuide and Gemstar argue that while the microcontroller must contain input/output interfaces, a microprocessor and an up-dateable memory, the microcontroller need not contain these elements within a single integrated circuit. Defendants contend the invention claims a single integrated circuit containing each of these elements. The plain language of the claim does not specify that the microcontroller be contained within a single integrated circuit. The Court therefore looks to the specification because “[c]laims must be read in view of the specification, of which they are a part.” Advanced Cardiovascular Sys., Inc. v. Scimed Life Sys., Inc., 261 F.3d 1329, 1338 (Fed.Cir.2001) (citations omitted). The specification contains the following: Microcontroller 60 comprises an eight-bit microprocessor, input/output interfaces and an updateable memory which is preferably a 32K random access memory (RAM). Those skilled in the art will of course appreciate that each element of microcontroller 60 may he separately provided, and that the microprocessor could be other than eight-bit, while the updateable memory could comprise a RAM, a hard disk, a floppy disk, bubble memory, tape, etc. and could be other than 32K in dimension. Reiter ’578, at Col. 4, 11. 9-18 (emphasis added). Additional changes to the system may be made by including one or more of the elements in a single piece of hardware, or by dividing a single element into many individual pieces. Thus, for example, the microcontroller, mixer and RF section could be combined into a single hardware chip. Conversely, the microcontroller could be divided into a microprocessor, a RAM and the various Z/O interfaces. Indeed, various combinations of all the elements could be made to suit various needs. Reiter ’578, at Col. 7, 11. 61-68; Col. 8, 11. 1-2 (emphasis added). The language of the specification clearly anticipates that each element of the microcontroller, i.e., the microprocessor, RAM and I/O interfaces, could be “divided” “into many individual pieces.” Moreover, while both the claim language (“including”) and the specification language (“comprises”) require the microcontroller to have at least these three elements, there is no requirement that the elements be contained within a single integrated circuit. “The claim word ‘including’ is not construed in a lexicographic vacuum, but in the context of the specification and drawings.” Toro Co. v. White Consol. Indus., Inc., 199 F.3d 1295, 1301 (Fed.Cir.1999). “The claim term ‘including’ is synonymous with ‘comprising,’ thereby permitting the inclusion of unnamed components.” Hewlett-Packard Co. v. Repeat-O-Type Stencil Mfg. Corp., Inc., 123 F.3d 1445, 1451 (Fed.Cir.1997). “‘Comprising’ is a term of art used in claim language which means that the named elements are essential, but other elements may be added and still form a construct within the scope of the claim.” Dow Chem. Co. v. Sumitomo Chem. Co., Ltd., 257 F.3d 1364, 1381 (Fed.Cir.2001) (quoting Genentech, Inc. v. Chiron Corp., 112 F.3d 495, 501 (Fed.Cir.1997)). And, where “including” or “comprising” is used in conjunction with the indefinite article “a,” the article “in patent parlance carries the meaning of ‘one or more’ in open-ended claims containing the transitional phrase ‘[including].’ ” KCJ Corp. v. Kinetic Concepts, Inc., 223 F.3d 1351, 1356 (Fed.Cir.2000). “The written description supplies additional context for understanding whether the claim language limits the patent scope to a single [integrated circuit] or extends to encompass a device with multiple [circuits].” Abtox, Inc. v. Exitron Corp., 122 F.3d 1019, 1024 (Fed.Cir.1997). Here, neither the language of the claim nor that of the specification requires the elements of the microcontroller to be integrated into a single circuit. Advanced Cardiovascular Sys., Inc., supra. Therefore, the undersigned will not read such a limitation into the claim. “Microcontroller” is thus construed as the electronics including input/output interfaces, a microprocessor, and an up-date-able memory comprising at least a random access memory which is capable of being updated via an electronic medium and which is capable of storing updated information including at least television programming information. The microcontrol-ler is not limited to a single integrated circuit. The next term for construction is “an electronic medium” which also is used in Claim 1, Element (a); “said RAM of said microcontroller being updateable via an electronic medium.... ” SuperGuide contends the term includes any electronically generated signal regardless of its source. Gemstar and Defendants agree that the phrase means any electronic medium that can be used to update the updateable memory of the microcontroller, including, as the specification discloses, digital information for the storage of programming information in the RAM. Super-Guide’s construction appears to agree with that of the Defendants and Gemstar. The specification provides: As indicated in FIG. 2, the random access memory or updateable memory of microcontroller 60 is subject to updating via electronic media. The particular medium chosen could be radio or television subcarrier 67a (via antenna 22 and RF section 64 if desired), telephone link 67b, magnetic cards or floppy disks 67c, or equivalents to any or all of the above. Regardless of the method of updating the RAM of microcontroller 60, the system 10 must additionally include suitable hardware and/or software for the updating task, such as a modem if telephone link 67b is utilized. Reiter ’578, at Col. 4,11. 29-89. The Court therefore construes the term “electronic medium” as an electronic medium that can be used to update the up-dateable memory of the microcontroller. However, the parties do not agree on the construction of “a mixer” and “a regularly received television signal” used in Element (b) of Claim 1; “a mixer for mixing a regularly received television signal with the signal generated by the micro-controller in accord with instructions of said microcontroller.” Figure 2 attached to the patent shows that the microcontroller sends program data to the mixer while the RF section sends video data to the mixer. The function of the mixer is to combine the two into one signal which is then sent to the RF section which transmits the signal to the television set. The combined information may be viewed, at the viewer’s discretion, either on a full screen or as an overlay or window in the television program being watched. At the hearing, the parties agreed the information generated by the microcontrol-ler would be in digital format. And, it was agreed that the video data was in analog format. The parties acknowledged that in order for the data from the microcon-troller to be mixed with the data from the RF section, they would have to both be modulated; or, if both were unmodulated, both would have to be either analog or digital, i.e., analog data cannot be mixed with digital data. Pointing to the language of the specification, Defendants claim the digital data from the microcontroller is converted by the mixer into an analog format before it is mixed with the video data in the mixer. SuperGuide argues this construction would import a limitation from the specification into the claim. Defendants also urge a construction which would add a description of “RF,” i.e., radio frequency, to the mixer. As will be apparent in the discussion of the phrase “regularly received television signals,” SuperGuide maintains that once the television signal is received from an outside source into the RF section, it is demodulated or stripped off of the carrier wave and becomes a baseband video signal. This, they argue, is verified by the use of the term “video data” to describe the signal sent to the mixer for mixing with the microcontroller program data. In fact, SuperGuide most recently claims the mixer did not have the capability to mix modulated signals and it was more likely that the video data was converted to digital format in the RF section before being sent for mixing with the digital data from the microcontroller. Moreover, SuperGuide alleges the Defendants’ construction would require modulation of the digital data from the microcontroller onto a carrier wave for transmission to the mixer. Finally, Su-perGuide argues that the mixer could also function as a video switch. See, Plaintiffs Proposed Memorandum and Order regarding Claim Construction, filed August 16, 2001, at 12-13. Gemstar urges a similar construction. The specification discloses that the RAM of the microcontroller stores the programming information. In order to receive information, the viewer, in essence, must direct the mi-crocontroller 60 through a series of steps. First the viewer might access the system microcontroller by pressing the # button on his remote control box 32. The viewer might then request that the information that he is about to demand be output on the television screen in a particular format. Thus, different codes could be used for output formats such as a window or overlay format, or a full screen display. Finally, the viewer would then request to see information contained in the RAM. For example, through a set of codes, the viewer might direct the microcontroller to output the television programming schedule for the week. The microcontroller, as a result of the commands, would direct RF section 6b to send received video signals to mixer 70. The microcontroller would also then access the RAM, and send the information to mixer 70 which is then receiving video data from antenna 22 or cable 2b via RF section 6b. The mixer 70, which is also powered by power supply 55, would take the information from microcontroller 60, convert it into a format which can be viewed in the same way [as] the video data received via RF section 6b, and mix the two in accord with the output format directed by the microcontroller. The mixed signal would then be sent via RF section 64 to the television 40 for viewing by the viewer. The invention envisions that additional information other than television scheduling information may be contained within the RAM of microcontroller 60.... An advertiser could arrange to have a message included in information down-loaded into the RAM of microcon-troller 60. The message might be accompanied by digital sound information which could be convened into analog signals in the RF section 6k and which would be perceived as electronic music. Reiter ’578, at Col. 4,11.57-68; Col. 5,11. 1-15, 37-39, 47-52 (emphasis added). The language of the specification teaches that the information transmitted by the mixer to the RF section is in analog format: “The mixed signal would then be sent via RF section 64 to the television 40 for viewing by the viewer.” The parties agree the television could only process analog signals. In contrast to SuperGuide’s argument, there is nothing in the claim language or the specification requiring that the microcontroller’s digital data be modulated onto an analog signal before being sent to the mixer. Nor has any party shown this was inherent in the state of the art at the time. Beam Laser Sys., Inc. v. Cox Communications, Inc., 144 F.Supp.2d 475, 487 n. 7 (E.D.Va.2001) (quoting National Recovery Techs., Inc. v. Magnetic Separation Sys., Inc., 166 F.3d 1190, 1196 (Fed.Cir.1999)). Indeed, at oral argument the parties acknowledged that signals generated internally within the system would not be so modulated because they were not to be transmitted over a long distance. “[T]he specification is always highly relevant to the claim construction analysis. Usually, it is dispositive; it is the single best guide to the meaning of a disputed term.” Vitronics, 90 F.Sd at 1582. In fact, the Federal Circuit has “specifically held that the written description of the preferred embodiments ‘can provide guidance as to the meaning of the claims, thereby dictating the manner in which the claims are to be construed, even if the guidance is not provided in explicit definitional format.’ In other words, the specification may define claim terms ‘by implication’ such that the meaning may be ‘found in or ascertained by a reading of the patent documents.’ ” Bell Atlantic Network, 262 F.3d at 1268 (quoting SciMed Life Sys., Inc. v. Advanced Cardiovascular Sys., Inc., 242 F.3d 1337, 1344 (Fed.Cir. 2001) and Vitronics, 90 F.3d at 1582, 1584 n. 6). The undersigned finds that such is the case here. The claim language is “a mixer for mixing a regularly received television signal with the signal generated by the microcontroller.” No one disputes the signal generated by the microcontroller is digital. The specification clarifies that the mixer “would take the information from [the] microcontroller [] convert it into a format which can be viewed in the same way [as] the video data received via RF section [ ], and mix the two .... ” The parties also agree that, at least as it is received in the RF section from the outside, the video data is in analog format. Thus, the mixer converts the digital signal into analog format and then mixes it with the video data. In other words, two analog signals are mixed. This construction is further supported by that portion of the specification describing the use of digital sound information received from the mi-crocontroller but converted into analog signals in the RF section. There is nothing in the language of the claim or the specification to support SuperGuide’s proposition that the video signal from the RF section is digitalized either prior to being transmitted to the mixer or by the mixer. Kopykake Enterprises, Inc. v. The Lucks Co., 264 F.3d 1377, 1383-84 (Fed.Cir.2001) (Licensee failed to show that from the point of view of one of ordinary skill in the art at the time the application was filed, the construction urged was appropriate.) The claim language and the specification clearly show that the conversion is of the information received from the microcon-troller into an analog format which is then mixed with the video data, also in analog format, and finally sent to the RF section. The focus in construing disputed terms in claim language is not the subjective intent of the parties to the patent contract when they used a particular term. Rather the focus is on the objective test of what one of ordinary skill in the art at the time of the invention would have understood the term to mean.... As [the Federal Circuit has explained], when a claim term understood to have a narrow meaning when the application is filed later acquires a broader definition, the literal scope of the term is limited to what it was understood to mean at the time of filing. Id., at 1383. Here, one of ordinary skill in the art in 1985 would have understood that the digital data received from the micro-controller would of necessity be converted into analog format. Thus, two analog signals were mixed. SuperGuide claims the analog television signal was demodulated in the RF section prior to being sent to the mixer. Accepting this proposition, it is clear that such a demodulated analog signal could be mixed with the unmodulated signal sent from the microcontroller once the digital format has been converted into analog format by the mixer. Indeed, all the parties agreed that demodulated and/or unmodulated signals which were both in analog format could be mixed. And, as noted infra, the digital signal coming from the microcontroller was not modulated onto a carrier wave. Thus, once converted in the mixer, it was an unmodulated analog signal which could be mixed with the demodulated analog signal received from the RF section. However, there is nothing in the claim language or the specification which would limit the signal received from the RF section to a demodulated analog signal, ie., a baseband video signal. In fact, there is nothing in the claim language or specification which requires that the analog signal be stripped off of the carrier wave in the RF section before being sent to the mixer, although this is not precluded by the claimed invention. Defendants argue the prosecution history shows that the signal received in the mixer from the RF section would not have been demodulated because a demodulated signal would not have been distinguishable from prior inventions. However, the undersigned’s review of that history does not support that conclusion. In response to the patent examiner’s rejection of the application, the patentee wrote: Bourassin et al. also does not provide a mixer for mixing a regularly received television signal with a signal generated by the microcontroller as is required by the instant invention.... [Bourassin shows] it is television signals which are being mixed with other television signals, and not television signals with signals generated by a microprocessor of the unit.... [N]or does Bourassin et al. output (and certainly not to a mixer which mixes a television signal with signals generated by a microprocessor ...). Prosecution History, at E028926 (emphasis added). The applicant also noted that “none of the cited patents appears to mix regular RF television station signals with information stored in the RAM and then overlay them as would be required by claims 10 and 11.... Lindman et al. does not have an RF section.... ” Id., at E028930. Contrary to the Defendants’ argument, the patentee’s focus is on the mixing of a computer generated signal with a television signal in order to distinguish the application from prior patents, not the mixing of modulated television signals. The patent examiner responded to the applicant’s comments by noting that Bour-assin “includes the function of regular TV receiving.” Id., at E028936. Regardless of whether the images included a “regular TV signal” mixed with another TV signal or with information from a computer, “such secondary signal to be mixed obviously is data from the various peripheral units of the microcontroller as claimed.” Id., at E028936-37. In response, the applicant noted that the prior patents cited did “not show an overlay of information obtained from a RAM over video information obtained from a TV station.... [T]he image-on-image of Bourassin is regular TV signals over secondary TV signals as opposed to TV signals overlayed by signals being generated by a microprocessor.” Id., at E028942. The Court rejects the Defendants’ argument that the prosecution history shows the patentee distinguished his invention from prior ones by claiming the mixing of a modulated signal in the mixer. The distinction was based on the mixing of a digital signal from a microcontroller internal to the invention with an analog television signal. Thus, as will be noted below, while the television signal which is received in the RF section was modulated onto a carrier wave, the claim language, the specification, the drawings and the prosecution history do not disclose whether the signal when received into the mixer has been demodulated. And, while the applicant argued to distinguish his invention, he did not amend or alter the claim language regarding this aspect of the invention in response to the examiner’s rejection. Kopykake, at 1382 (“Unless altering claim language to escape an examiner’s rejection, a patent applicant only limits claims during prosecution by clearly disavowing claim coverage.” (citations omitted)). The Court therefore rejects both the Defendants’ position that the mixer mixed modulated signals and SuperGuide’s argument that the mixer could only mix demodulated and/or unmodulated signals. Likewise, there is no support for Super-Guide’s argument that the digital data must have been modulated onto a carrier wave for transmission from the microcon-troller to the mixer. Dow Chem. Co., 257 F.3d at 1379 (The district court “improperly imported a limitation not supported by the claim language or the specification.”). The patent makes no such disclosure. Nor it is necessary, as the Defendants claim, to add the description “RF” to the mixer. Gart v. Logitech, Inc., 254 F.3d 1334, 1343 (Fed.Cir.2001). The claim and specification describe a mixer having the capability to convert digital data from the microcon-troller into an analog format which is then mixed with an analog signal to generate an analog signal to the RF section. To add the term “RF mixer” would import a limitation not claimed in either the claim language or the specification; and, as previously noted, not clearly defined by the prosecution history. The Court also rejects the contention by SuperGuide and Gemstar that the mixer functioned as a video switch. Nothing in the claim language or the specification supports the addition of such a description. The specification clearly states that the “mixer 70, ... would take the information from microcontroller 60, convert it into a format which can be viewed in the same way as the video data received via RF section 64, and mix the two in accord with the output format directed by the micro-controller. The mixed signal would then be sent via RF section 6k to the television k0 for viewing by the viewer.” The forwarding of a mixed signal does not describe a system which switches back and forth between the video of a television program being shown and the text of the programming information stored in the RAM. The determined information located by the microcontroller is then controllably sent to the mixer which, in accord with instructions from the microcontroller, properly mixes the requested information with the rf video data being received from the antenna or cable. In addition, ... the mixer is told by the viewer, via instructions of the microcon-troller, ivhether to scroll the desired information, or whether and when to display new full ivindows or screens of information. After the search has been accomplished and displayed, the viewer may then choose at 170 whether to perform an additional search, or whether to exit the system.” Reiter ’578, at Col. 6, 11. 42-54 (emphasis added). There is no language in the specification supporting a “switch” theory; indeed, the specification details the selection of programming information followed by an additional search or an exiting of the system. Such language would be unnecessary if the viewer could simply switch back and forth between the programming information and the television program being viewed. “The construction of claims is simply a way of elaborating the normally terse claim language in order to understand and explain, but not to change, the scope of the claims.” Embrex, Inc. v. Service Eng’g Corp., 216 F.3d 1343, 1347 (Fed. Cir.2000) (citations omitted). SuperGuide and Gemstar also argue that “switching” refers to the interleaving of signals in order to display the program guide in the format chosen by the viewer simultaneously with the television program itself. “[T]he mixer ‘interleaves’ (alternates between) the first and second signal ‘on the fly’ to generate a combined signal that displays the IPG and the television program in the proper format.” Gemstar Development Corporation’s Markman Brief, at 27. [A]s the electron beam scans across a row [of pixels] and reaches the left edge of the portion of the screen reserved for the IPG window, the mixer switches the signal sent to the television set to the IPG signal from the microcontroller, i.e., the IPG signal.... The location of the window is determined by a control signal sent from the microcontroller to the mixer to indicate the points at which transitions back and forth between the two input signals to the mixer are to occur. By this method, the output signal contains a combination of the second signal ‘interleaved’ within the first signal in a manner that results in the display of an IPG window. Id., at 28-29 (emphasis added). The undersigned does not construe “interleaving” as equivalent to “switching.” The specification clearly describes a “combination” signal resulting from the interleaving process, not an alternating between signals. Gemstar and SuperGuide acknowledge that the technology for interleaving and superimposing signals “was well known and in practice in 1985.” Id. Thus, the Court rejects an attempt to convert technology well known in the art into a new function not described or claimed in the patent, ie., switching. The Court therefore construes the term “mixer” to mean the electronics for (a) receiving and converting an unmodulated digital signal generated by the microcon-troller which contains television programming information into an analog format; (b) receiving a regularly received television signal, whether demodulated or unmo-dulated, which contains television video information; (c) receiving and stripping' a modulated analog signal which contains television video information from the RF section; and (d) mixing the two compatible signals to produce an analog signal which is then transmitted to the RF section. The mixer does not function as a switch. The same principles apply to the construction of the phrase “regularly received television signal.” SuperGuide and Gemstar urge a construction that is not limited to a method of broadcast transmission, ie., the carrier wave may be modulated with either analog or digital data containing the television audio and video information. Defendants argue against this construction because in 1985 a television set could not process digital satellite signals. However, the parties do agree that in 1985 the analog baseband video signal produced by the television camera could not be broadcast without modulation onto a carrier wave and that television signals were broadcast in this manner. Again, resort to the specification is sufficient. The specification makes it clear that the programming guide was independent of regular television viewing. Power switch 50 is used for turning the system on or off and may be driven by a standard electrical outlet. When the system is turned on, power supply 55 is used to provide the low voltages necessary to power the microcontroller 60. When the system is off, television signals received, such as VHF/UHF channels 2-82, or cable channels 2-62, are sent directly through RF section 64- to the television 40 for viewing. Reiter ’578, at Col. 4, 11. 1-8 (emphasis added). In 1985, only analog signals could be directly processed by the television set. The apparent reason for the patent’s focus on analog signals is that television broadcasting in the early 1980s was conducted solely in an analog format. [The] parties acknowledged during oral argument that digital television signals were not developed until after the date of invention. Because the literal scope of the [’578] patent was fixed at the date of issuance, the claims must be construed to refer to the kinds of television signals that were being [broadcast] at that time. IPPV Enter., 106 F.Supp.2d at 606. Thus, the phrase “regularly received television signal” means an analog signal modulated onto a carrier wave and transmitted via terrestrial antennae or through a cable or satellite system. It does not include a digital television signal as understood in the state of the art in the mid-1990’s. The next portion of Claim 1 which must be construed is Element (c) which provides for “an RF section for receiving instructions from said microcontroller and for receiving radio frequency information from the mixer and a television station and properly converting the information into video signals which may be sent to said television for viewing[.]” SuperGuide’s position is that the language of the claim constitutes a definition of “RF section.” Defendants cite the specification to support their position that the RF section must include a tuner and converter. The claim and the specification recite three functions for the RF section. The first function is performed when the programming guide is off: “television signals received, such as VHF/UHF channels 2-82, or cable channels 2-62, are sent directly through RF section 64 to the television 40 for viewing.” Reiter ’578, at Col. 4, 11. 1-8. The second function occurs when the viewer uses the programming guide as a remote control system: “The system 10 may therefore function simply as a remote control device which permits the viewer to change channels. In this mode, according to the command of control unit 32, the microcontroller 60 instructs RF section 61 as to which channel is to be received from antenna 22 or cable 21 and sent to the television 10 for viewing on locally non-used channel 3 or 4.” Id., at Col. 4, 11. 21-28 (emphasis added). The third function involves the use of the programming guide by the viewer: “The mixed’ signal would then be sent via RF section 64 to the television 40 for viewing by the viewer.” Id., at Col. 5,11.13-15. Because the inventor clearly intended the system to function as a remote control device, the RF section must. include a method for selecting one channel from the many being bombarded at the television. “ ‘[A] claim interpretation that would exclude the inventor’s device is rarely the correct interpretation.’ ...” Interactive Gift Express, 256 F.3d at 1343 (quoting Modine Mfg. Co. v. U.S. Int’l Trade Comm’n, 75 F.3d 1545, 1550 (Fed.Cir.1996)). Thus, it is unlikely that those skilled in the art would read the claim and specification as not including such a device. Id. Likewise, the RF section must convert information received from the mixer and the television station into “video signals which may be sent to said television for viewing.... ” Thus, a conversion device is prescribed by the invention. Reiter ’578, supra. The Court finds the term “RF section” to mean the electronics for (1) receiving radio frequency signals from a source external to the invention; (2) receiving instructions from the microcontroller internal to the invention; (3) making a channel selection pursuant to the instructions received from the microcontroller; (4) receiving and converting signals received from the mixer or a television station into video signals capable of being received by the television set; and (5) transmitted the converted signals to the television for viewing. Element (c) of claim 1 contains the phrase “radio frequency information” which is described as coming from the mixer and a television station. Super-Guide argues that “radio frequency information” is either analog or digital information which may be carried or derived from a radio frequency carrier signal. And, SuperGuide notes the information received from the mixer is not modulated but still qualifies as radio frequency information because it can be modulated in the RF section for viewing on a television. Thus, digital television signals also qualify as radio frequency information because they may be modulated onto a carrier wave. The Court rejects this attempt to bootstrap technology which was not in the state of the art at the time of this invention. The specification provides that when the programming guide is not in use, “television signals received, such as VHF/UHF channels 2-82, or cable channels 2-62, are sent directly through RF section 64 to the television 40 for viewing.” Reiter ’578, at Col. 4, 11. 5-8. The Court has construed “regularly received television signals” to mean analog signals. The Federal Circuit has indicated that in certain situations, a narrow written description may constitute a basis for adopting a narrow construction of otherwise-broad claim language. The Federal Circuit has held that the literal meaning of a claim is fixed upon its issuance. Variants of a claimed invention that are based on after-developed technology could not have been disclosed in a patent. When a claim is written sufficiently broadly to cover after-developed technologies, the claims may be construed to limit their scope to those technologies disclosed in the written description of a patent. IPPV Enter., 106 F.Supp.2d at 605 (quoting Wang Labs., Inc. v. America Online, Inc., 197 F.3d 1377, 1383 (Fed.Cir.1999) (“The only embodiment described in the ’699 patent specification is the character-based protocol, and the claims were correctly interpreted as limited thereto.”)) (other internal citations omitted). Such is the case here. The specification limits radio frequency information to the type of television signals being broadcast in 1985 and may not be broadened to encompass the construction urged by SuperGuide and Gemstar. Thus, the phrase is construed to mean modulated or unmodulated analog signals containing television programming and video information received either from the mixer internal to the system or from a television station. It does not include digital television signals. Element (d) of Claim 1 is also subject to claim construction: “a remote control system ... for permitting a viewer of said television to direct said microcontroller to perform a search on at least said updated television programming information contained in said RAM of said micro-controller .... ” Gemstar and the Defendants agree that the phrase “to perform a search” means that the viewer would direct the microcontroller to retrieve all of the desired programming information of a particular type, e.g., all sports programs or all movies. SuperGuide maintains the phrase means to retrieve at least a subset of the programming, i.e., an examination of less than all the records in RAM. The specification provides: If the viewer wished to view a subset of the information, e.g., the television program schedule for the day, the viewer, through a different set of code signals which might include the direct keying of the date on the handheld remote control unit 32, could then direct the microcon-troller to output only a part of the information stored in the microcontroller RAM. Likewise, if the viewer wished to see a listing of the sports events being shown on television on a particular day, the viewer could direct the microcon-troller to search through the information in the RAM and retrieve only the requested information. The next command of the viewer at 105 might indicate whether the viewer wished to see all of the information contained in the RAM, e.g., a complete dump of the RAM, or whether a subset of that information was desired.... In this manner, the microcontroller would perform the function of a microprocessor in performing a search on the information contained in the RAM and determining, for example, a listing of all the television movies that are to start between 6 and 11 P.M. on a particular date. Reiter ’578, at Col. 5.11. 16-27, 67-68; Col. 6 11. 1-3, 17-21 (emphasis added). It is clear from the language of the claim and the specification that the search is of all the information contained in the RAM in order to produce the subset of data specified by the viewer. In addition, the invention envisioned the storage of information unrelated to television programming, such as local movie times, in the RAM. Id., at Col. 5 11. 37-49 (“The invention envisions that additional information other than television scheduling information may be contained within the RAM of microcontroller 60.”); Col. 6 11. 60-68. Thus, the claim provides that the search will be conducted on “at least said updated television programming information.” The Defendants’ construction is therefore the appropriate one. The phrase “to perform a search” means a user-directed examination by the microcontroller of all the television programming information stored in the random access memory of the system and the retrieval of a subset of that information which meets the criteria specified by the user for display on the television set. Finally, the last element of Claim 1 is the “desired format” for viewing the television programming information: “a subset of at least said updated television programming information being output to said mixer so as to provide on the television screen television programming information desired by the viewer in a desired format.” Defendants maintain the format is limited to that chosen by the viewer and may not include preselections determined by the service provider. SuperGuide and Gemstar claim the format includes selections by the user, the system designer or the service provider. SuperGuide bases this conclusion on the fact that the system is preprogramed for a full screen, window or overlay format. Thus, it argues the system designer has “selected” those formats. The specification provides the following: Indeed, if desired, mass media advertising could be accomplished according to the invention. An advertiser could arrange to have a message included in information down-loaded into the RAM of microcontroller 60. The message might be accompanied by digital sound information [].... In this manner, a jingle or theme song might accompany the advertising message. The next command of the viewer at 105 might indicate whether the viewer wished to see all of the information contained in the RAM, e.g., a complete dump of the RAM, or whether a subset of that information was desired. If a complete dump was requested, the mi-crocontroller would direct the viewer to choose a format of display.... [If] the viewer has directed the microcontroller to perform [a] subset search, the viewer is directed to determine the format output of the information found. Thus, at 145, the viewer is asked whether an entire screen format is desired. If not, at 150, the viewer is asked whether a window format is desired. If not, the viewer is supplied at 155 with a television overlay format.... In addition, at 160 and 165, the mixer is told by the viewer, via instructions of the micro-controller, whether to scroll the desired information, or whether and when to display new full windows or screens of information. Id., at Col. 5 ll. 45-54, 67-68; Col. 6 ll. 1-5, 29-36, 48-51. Thus, the invention provides at least three formats: entire screen, window or overlay. The viewer must select one of the first two options or the third “overlay” is provided. Thus, by not selecting one of the first two choices, the viewer in fact selects the “overlay” format. The undersigned does not construe this language so broadly as to encompass other formats, as opposed to additional information, preselected by the service provider. The specification clearly states that although additional information may be included in RAM, such as the advertising jingle, the format in which it is viewed is selected by the viewer. This invention was designed for viewer selection of the format in which he desired to view the television programming information. The choice of formats of necessity is included within the system by the system designer. The fact that the system designer provides certain choices does not mean that it “select” a desired format. The term “desired format” means a user selected format for the display of the results of the search performed by the system. Although additional information may be provided to the system by the service provider, the format for viewing that information is viewer directed. U.S. PATENT 5,038,211 to HALLEN-BECK The Reiter ’578 invention had two drawbacks: the necessity for random access memory capable of storing voluminous information and the requirement of a high speed processor capable of processing that information. These aspects of the invention presented economic obstacles to its commercialization due to the high cost of microcontrollers and microprocessors capable of performing these functions. Hal-lenbeck ’211, applied for in 1989 and issued in 1991, solved these problems by storing only those television programs meeting predetermined selection criteria thus reducing the necessity for large memory and high speed processors. The invention stores three groups of information: event data, program title and program description. The parties agree that Claims 1 and 2 of Hallenbeek ’211 are written as “means-plus-function” claims limitations. Title 35, United States Code, § 112 allows a paten-tee to write a claim by reciting the function to be performed by the invention instead of by specifying the structure which performs that function. Lockheed Martin Corp. v. Space Systems/Loral, Inc., 249 F.3d 1314, 1323-24 (Fed.Cir.), petition for cert, filed September 21, 2001. In construing means-plus-function claim limitations, a court must first define the particular function claimed. Thereafter, it must identify “the corresponding structure, material, or acts described in the specification.” It is not until the structure corresponding to the claimed function in a means-plus-function limitation is identified and considered that the scope of coverage of the limitation can be measured. Whether or not the specification adequately sets forth structure corresponding to the claimed function necessitates consideration of that disclosure from the viewpoint of one skilled in the art. Moreover, failure to disclose adequate structure corresponding to the recited function in accordance with 35 U.S.C. § 112, paragraph 1, results in the claim being of indefinite scope, and thus invalid, under 35 U.S.C. § 112, paragraph 2.... [A] challenge to a claim containing a means-plus-function limitation as lacking structural support requires a finding, by clear and convincing evidence, that the specification lacks disclosure of structure sufficient to be understood by one skilled in the art as being adequate to perform the recited function. Budde v. Harley-Davidson, Inc., 250 F.3d 1369, 1376-77 (Fed.Cir.2001) (internal citations omitted). Thus, “the determination of the corresponding structure of a means-plus-function claim is a determination of the meaning of the ‘means’ term, and is a matter of claim construction” for the court. Globetrotter Software, Inc. v. Elan Computer Group, Inc., 236 F.3d 1363, 1367 (Fed.Cir.2001). Claim 1 of Hallenbeck ’211: Hallenbeck ’211 is described as an online television program information system which extracts from a broadcast data-stream of television program information only that information for shows which meet predetermined selection criteria and stores only that extracted information. The language of Claim 1 which is to be construed is set forth in bold font. That which is claimed is: 1. An online television program schedule system comprising: first means for storing at least one of a desired program start time, a desired program end time, a desired program service and a desired program type; means for receiving television program schedule information, said television program schedule information comprising at least one of program start time, program end time, program service, and program type for a plurality of television programs; second storing means connected to said first storing means and said receiving means, for storing selected portions of received television program schedule information which meet at least one of the desired program start time, the desired program end time, the desired program service, and the desired program type; and displaying means, operatively connected to said second storing means, for displaying at least part of the selected portions of received television program schedule information to thereby provide an online television program schedule. Hallenbeck ’211, at Col. 8 11. 4-27. The phrase “first means for storing” clearly identifies the function of the claim as “storing at least one of a desired program start time, a desired program end time, a desired program service and a desired program type.” Lockheed Martin, 249 F.3d at 1324 (“The phrase ‘means for’ ... is typically followed by the recited junction and claim limitations.”). “The function of a ‘means plus function’ claim must be construed to include the limitations contained in the claim language.” Id. Thus, the function cannot be construed as only “first means for storing” without the limitations contained in the claim language. “Having identified the function of [the] limitation, [the Court] next construe[s] the meaning of the words used to described the claimed function, using ordinary principles of claim construction.” Id. The parties agree that “program service” means a particular provider of television programming, such as HBO, and that “program type” means a classification of television programming, such as sports, news, movies, etc. Start and end times are given their ordinary meaning. Vitronics, 90 F.3d at 1582-83. Thus, the meaning of the remaining language of the limitation is “clear from the plain language of the claim and is consistent with the intrinsic evidence.” Lockheed Martin, supra. As noted above, the function of storing is directed to and limited by the claim language as “at least one of a desired program start time, a desired program end time, a desired program service and a desired program type.” Id. (“The function of a ‘means plus function’ claim must be construed to include the limitations contained in the claim language.”). The next step in construing this means-plus-function limitation is to review “the written description to identify the structure corresponding to the function.” Id., at 1325. “As a