Creo Products, Inc. v. Presstek, Inc., Defendant-Cross
Docket: 02-1023
Court: Court of Appeals for the Federal Circuit; September 17, 2002; Federal Appellate Court
Creo Products, Inc. appeals a ruling from the U.S. District Court for the District of Delaware, which upheld the validity of two patents owned by Presstek, Inc. Presstek cross-appeals the court's finding that Creo's on-press imaging system does not infringe these patents. The Federal Circuit affirms the district court's decision.
The ruling discusses the principles of printing technology, particularly offset lithography, which has remained fundamentally unchanged despite advancements. In this process, an image is created on a printing plate by altering its surface areas to be either ink receptive or repellant, typically using a discharge source. The inked plate then transfers the image to paper via a blanket cylinder, characteristic of offset printing.
The case centers on color offset lithography, which requires separating a color image into four components (yellow, cyan, magenta, and black) and transferring each to its respective printing plate. The alignment of these colors on paper is critical; any misregistration can lead to visibly distorted images. Misregistration can arise from various errors: non-uniform errors affect parts of the image, while uniform errors impact the entire image. Specific types of uniform errors include axial errors (lateral shifts), angular offset errors (vertical shifts), size errors (differences in dimensions), and skew errors (twisting of images).
Misregistration in printing can be corrected manually, but this method is costly and labor-intensive, especially for non-uniform errors. Electronic error correction is preferred due to its efficiency and ability to address both uniform and non-uniform errors. It involves creating the image directly on the plate while on the press, which allows for real-time modifications to correct errors.
Presstek holds U.S. Patent Nos. 5,163,368 ('368 patent) and 5,174,205 ('205 patent), both of which were reexamined and amended in August 1999. The '368 patent describes a printing apparatus capable of electronically correcting mechanical imperfections causing alignment and registration errors, with the independent claim detailing a system that includes multiple print stations, a control mechanism for applying an image to a plate, and means to adjust for angular and size inconsistencies using a dot position look-up table.
The '205 patent outlines an apparatus and method for controlling discharges used to image printing plates, with its independent claims focusing on the structure for mounting plates and facilitating the scanning of the printing surface by discharge means.
Controlling means are designed to respond to image information that identifies specific locations on a cylinder for discharges, along with position information related to the discharge means' location and correction data for image offsets. These controlling means are connected to the discharge means, ensuring that discharges occur at designated positions on the printing surface, producing an array of image spots aligned with the represented image.
The imaging method involves several steps: 1) mounting a lithographic plate on the plate cylinder; 2) receiving position information indicating the cylinder's angular position; 3) storing image information for image spot locations and correction offsets; 4) exposing the printing surface to discharges from an imaging device to create image spots; 5) moving the imaging device relative to the cylinder to scan the printing surface; and 6) controlling discharges based on image, correction, and position information to produce an array of image spots for reproduction in circumferential imaging swaths.
In 1997, Creo developed the DOP System for on-press imaging, sold as a kit to printing press manufacturers rather than being incorporated directly. The system connects to a computer with a graphical user interface allowing users to enter five geometric correction parameters: main scan shift (circumferential adjustment), sub scan shift (axial adjustment), main scan scale (image size adjustment in the y-direction), sub scan scale (image size adjustment in the x-direction), and track rotation (image axis compensation). The imaging process begins with sending an image file to an image processor that decomposes the image into pixels, creating bitmaps for each color, which are stored on a hard disk prior to imaging.
The Creo DOP System initiates imaging based on five geometric correction parameters, reading image bitmaps from a hard disk and transmitting pixel groups to FIFO memory on the Image Control Electronics (ICE) board at each print station. It processes groups of up to 240 pixels at a time to create images on the printing plate using a laser diode and a light valve, with the Thermal Exposure Head moving axially as the plate cylinder rotates. To ensure uniform pixel spacing despite cylinder speed variations, the system employs a center frequency calculation (CFC) that continuously analyzes and predicts drum speed, adjusting 256 times per cylinder rotation.
In 1999, Creo sought a declaratory judgment to declare the '368 and '205 patents invalid, non-enforceable, and not infringed by its imaging system. Presstek counterclaimed, alleging inducement of infringement. Following a Markman hearing, the district court found the patents valid and ruled Creo not liable for contributory infringement. Creo appeals, arguing claim 1 of the '368 patent was improperly broadened during reexamination and that both claim 1 of the '368 patent and claim 11 of the '205 patent are indefinite due to lack of corresponding structure in their means-plus-function limitations. Presstek cross-appeals, contending the district court misconstructed certain claims and erred in finding no infringement by the Creo DOP System.
A patentee cannot expand a patent claim's scope during reexamination per 35 U.S.C. 305. The court reviews whether amendments broaden a claim de novo, comparing pre-reexamination and post-reexamination scopes. In this case, the disputed claim limitations involve specific actions for offsetting discharge-source actuation and altering scan lengths to correct imaging inconsistencies. The appeal focuses on the original claim's scope.
The '368 patent describes four correctable imaging errors: axial (x-direction), circumferential (y-direction), image size, and skew errors. A dispute arises regarding original claim 1's requirement for a structure to correct all four errors, as asserted by Creo, versus a structure capable of correcting any imaging error. Creo claims that the "means for offsetting" in original claim 1 necessitates a computer programmed to address all four errors, while Presstek's reexamination amendments allegedly reduced this requirement to correcting only y-direction and image length errors. Creo argues that a device correcting only y-direction and image length errors could infringe the reexamined claim but not the original claim, suggesting the reexamined claim is broader.
The court counters that Creo improperly redefines the "means for offsetting" function, which must derive from the original claim language. The original claim specifies offsetting to correct imaging errors without mandating a particular combination of corrections. Creo also contends that the presence of four algorithms in the patent necessitates a singular computer programmed to perform all four. However, the court clarifies that the written description allows for alternative structures and does not require a single embodiment to perform all algorithms. Additionally, Creo's interpretation conflicts with the doctrine of claim differentiation, as original dependent claim 2 includes means for applying position offset signals for x and y corrections, which would be redundant if original claim 1 already required correction for all four errors.
The prosecution history does not support Creo's claims regarding the limitations of original claim 1, which initially lacked any image correction capabilities, present only in dependent claims 2 and 3. The Patent Office rejected claim 1 as obvious under 35 U.S.C. 103 based on several prior patents. To address this rejection, Presstek added a "means for offsetting" limitation. Creo's argument, based on a statement from Presstek that the new limitations were added to overcome prior art rejections, is dismissed; the court determines that this statement does not narrow the "means for offsetting" to a structure that corrects all four imaging errors mentioned in the specification. The court emphasizes that restricting a means-plus-function limitation to a function not explicitly stated in the claim is improper, referencing established case law. The district court correctly concluded that the function in original claim 1 does not necessitate correction of all four error types, thus confirming that claim 1 was not improperly broadened during reexamination.
Additionally, Creo contends that claim 1 of the '368 patent is invalid due to indefiniteness, arguing insufficient structural disclosure for the "means for rotating each cylinder" and a similar claim in the '205 patent. Presstek's assertion that Creo did not preserve these indefiniteness arguments for appeal is rejected, as Creo had adequately raised these points during claim construction, which the district court implicitly addressed by identifying sufficient structure in its rulings. The specification of the '368 patent describes two embodiments for the "means for rotating each cylinder" limitation: a conventional in-line configuration and a central impression cylinder design, which simplifies the printing process.
Proper application of 35 U.S.C. § 112, ¶ 6 recognizes that claim elements can encompass distinct and alternative structures for performing a claimed function, as established in case law. Structures disclosed in a patent specification may include various alternative embodiments, validating the claim even if only one embodiment reveals corresponding structure. The "central-impression" embodiment of the '368 patent specifies that "the impression cylinder drives each plate cylinder," while the "in-line" embodiment's clarity is supported by Figure 1, which illustrates that each print cylinder rotates on a spindle, a common structure in the industry per expert testimony.
The specification of the '368 patent sufficiently discloses the structure necessary to fulfill the "means for rotating" limitation of claim 1. Additionally, claims for further required structures are deemed implicit within the '368 patent's disclosure. Existing case law allows the understanding of a skilled individual to expand upon structural references in a specification to meet the definiteness requirement. For instance, references to a "selector" and "commercially available vacuum sensors" have been previously accepted as adequate.
The evaluation of whether the specification provides sufficient structure to support a means-plus-function limitation hinges on the perspective of a skilled artisan. It is acknowledged that the method of rotating plate cylinders in a printing press is well understood, thus detailed explanation in the specification is unnecessary. The record includes Presstek's U.S. Patent No. 4,911,075, which indicates that the print cylinder in an in-line press is typically rotated by a standard electric motor, underscoring that such structures are common knowledge among those skilled in the art.
The "mounting means" limitation in claim 11 of the '205 patent is illustrated in Figure 1, depicting a V-shaped "cut-out portion" in the print cylinder that facilitates securing or removing the printing plate. Presstek's expert confirmed that this V-notch is a conventional mounting system, supported by the presence of a similar structure in the '075 patent. The expert's testimony, deemed unrebutted, indicates that the mounting structures outlined in the '368 and '205 patents are well-known in the field, further substantiated by their characterization as "conventional" in prior patent filings. Creo failed to provide evidence contradicting the expert's opinion regarding the "means for mounting" or "means for rotating" limitations, thus not overcoming the presumption of validity for the '368 and '205 patents.
The district court concluded that Creo's DOP System does not infringe claims 1 of the '368 patent and claims 11 and 23 of the '205 patent based on three reasons, with the primary reason being the lack of "point-by-point" discharge correction capability in the DOP System. Claims 11 and 23 require that discharges be controlled to correspond to discrete positions on the printing surface, which the district court interpreted in alignment with the patent's written description emphasizing precise control of discharges to create accurate image spots.
The district court's interpretation of claims 11 and 23 of the '205 patent is strongly supported by the reexamination record, where Presstek emphasized that these claims necessitate control and correction of discharges on a "point-by-point" basis to differentiate its invention from prior art. Notably, Presstek amended the claims after the examiner rejected them as obvious, clarifying that the claims require discharges at specific discrete positions on the printing surface, offset by correction data. Mitsuka's prior art was distinguished as it did not involve the correction of individual discharges, which is central to claims 11 and 23.
Additionally, Presstek reiterated the importance of "discrete image spots" and positional corrections in various statements during reexamination, asserting that its invention allows for corrections on a point-by-point basis. This assertion was reinforced in an information disclosure statement, where Presstek claimed that a referenced prior art did not alter dot-to-dot spacing as required by its claims.
Presstek's argument that the doctrine of claim differentiation prevents a point-by-point interpretation is unsubstantiated, as claims 12 and 24, while similar, specify additional aspects concerning varying discharge intervals. There is no redundancy between these claims, meaning Presstek's differentiation argument lacks merit. Furthermore, Presstek's attempt to redefine "point-by-point" correction as applying to all points—uniformly or non-uniformly—contradicts its prior representations made to secure the patent's allowance. The district court correctly determined that the claims necessitate independent corrections at discrete positions.
The district court determined that the Creo DOP System cannot perform point-by-point corrections as required by claims 11 and 23 of the '205 patent, concluding that the system's Center Frequency Calculation (CFC) can make corrections only every one-tenth inch, not independently for individual points. Consequently, the court affirmed the finding of non-infringement of the '205 patent. The court did not consider Presstek's arguments regarding the NTU buffer and tach history buffer or other non-infringement grounds related to specific imaging limitations.
Regarding the '368 patent, the court identified three independent reasons for finding that the Creo DOP System does not infringe claim 1. The key issue addressed was the absence of a "dot position look-up table" that stores x and y coordinates for all dot positions on each plate. The court rejected Presstek's assertion that the image bitmap in the Creo DOP System fulfills this requirement, stating that the claimed table is static for each print station, whereas the bitmap changes with each image. Presstek contended that the term should be interpreted broadly to include any data storage structure. However, the court found that Presstek's argument ignored the specific limitation of storing coordinates relevant to each plate, which was central to the claim.
The "substantially all" language in the claim limitation indicates that dot positions are permanently stored in the controller as pedigree for each print station. The district court determined that the bitmap in the Creo DOP System contains image information, not plate information, and therefore does not store "substantially all" dot positions on each plate due to its variable size with different images. Presstek contends that the Creo DOP System has an equivalent to the dot position look-up table through five geometric correction parameters (GC—Params) used for real-time corrections. However, the district court ruled that the GC—Params do not perform the same function in the same manner to achieve the same result as the claimed look-up table, emphasizing differences in complexity, speed, and control of dot positions. Consequently, Presstek failed to prove that the district court's non-equivalence finding was clearly erroneous, leading to the affirmation of the conclusion that the Creo DOP System does not infringe claim 1 of the `368 patent. The court does not address Presstek’s other arguments concerning the absence of specific limitations related to actuation. A dissenting opinion raises concerns about the structure disclosed in the `205 patent in relation to means-plus-function limitations.
The majority opinion presents ambiguity regarding the structure related to the means for rotating the plate cylinder. Figure 1 illustrates an alternative embodiment where the impression cylinder drives each plate cylinder, indicating that the impression cylinder 28d indirectly causes the rotation of plate cylinder 24d through the blanket cylinder 26d. The means for rotating applies solely to the plate cylinders, thus no structure needs to be disclosed for the impression cylinder. As long as the written description includes specific structures corresponding to the means for rotating the plate cylinders, the patent can withstand validity challenges. The presence of the impression cylinder as the driving force supports the conclusion that the `368 patent remains valid, despite doubts about the adequacy of Figure 1 as evidence of structure, which only shows a hole in the plate cylinder without additional details like a spindle.
Conversely, the `205 patent lacks an alternative embodiment for the "mounting means," rendering it invalid. Claim 11 states there is a "mounting means for mounting said plate on said cylinder," with the district court identifying the structure in Figure 1 as a V-notch cut-out. However, the V-notch merely indicates access to the mounting means rather than describing the means itself. Testimony suggests that the V-notch would typically contain a hold-down mechanism, but evidence regarding its function is deemed irrelevant without corresponding structure disclosed in the written description. Thus, the bare V-notch disclosure does not satisfy the requirements of section 112(6), leading to the conclusion that the `205 patent should be declared invalid. The author diverges from the majority opinion on this issue, although they agree with the majority in other respects.
