Cedar Lane Tech Inc v. Sigma Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Cedar Lane Technologies Inc. (Canada)
  • Defendant: Sigma Corporation (Japan)
  • Plaintiff’s Counsel: Rabicoff Law LLC
• Case Identification: 6:22-cv-01051, W.D. Tex., 10/06/2022
• Venue Allegations: Venue is alleged to be proper because the defendant is a foreign corporation, and further alleged that the defendant committed acts of patent infringement and caused harm within the district.
• Core Dispute: Plaintiff alleges that Defendant’s products infringe patents related to a host interface for managing data transfer from an imaging array to a processor system.
• Technical Context: The technology addresses the interface between CMOS image sensors and host processors, a fundamental component in digital cameras and other electronic imaging systems.
• Key Procedural History: U.S. Patent No. 8,537,242 is a divisional of the application that resulted in U.S. Patent No. 6,972,790. The complaint asserts that Defendant gained actual knowledge of the alleged infringement upon service of the complaint.

Case Timeline

Date	Event
2000-01-21	Priority Date for ’790 and ’242 Patents
2000-12-21	Application filed for what became the ’790 Patent
2005-10-27	Application filed for what became the ’242 Patent
2005-12-06	’790 Patent Issued
2013-09-17	’242 Patent Issued
2022-10-06	Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,972,790 - Host interface for imaging arrays

Issued December 6, 2005

The Invention Explained

• Problem Addressed: The patent’s background section describes a technical incompatibility between the continuous, high-speed "video style output" of CMOS image sensors and the data input/output interfaces of commercial microprocessors. This mismatch historically required "additional glue logic" and custom interface circuitry, which "diminishes the benefit" of using low-cost, integrated CMOS sensors (ʼ790 Patent, col. 1:47-67).
• The Patented Solution: The invention proposes an interface, preferably integrated onto the same semiconductor die as the image sensor, that bridges this gap. The interface uses an internal memory, such as a First-In-First-Out (FIFO) buffer, to temporarily store image data received from the sensor at the sensor's clock rate. It then generates a signal (e.g., a processor interrupt) to notify a host processor that data is available, allowing the processor to read the data from the memory at its own, different rate (ʼ790 Patent, Abstract; col. 2:4-14). Figure 2 of the patent illustrates this architecture, showing an interface (13) with a FIFO buffer (44) and an interrupt generator (48) positioned between the imaging array (21) and the system bus (15).
• Technical Importance: This architecture simplifies system design by eliminating the need for external interface components, allowing a standard microprocessor to communicate directly with an imaging sensor chip and thereby realizing the full cost and integration advantages of CMOS technology (ʼ790 Patent, col. 1:63-67).

Key Claims at a Glance

• The complaint alleges infringement of exemplary claims from the patent but does not identify them by number (Compl. ¶12). Independent claim 1 is representative of the invention's core system:
  • An interface for receiving data from an image sensor having an imaging array and a clock generator for transfer to a processor system comprising:
  • a memory for storing imaging array data and clocking signals at a rate determined by the clocking signals;
  • a signal generator for generating a signal for transmission to the processor system in response to the quantity of data in the memory; and
  • a circuit for controlling the transfer of the data from the memory at a rate determined by the processor system.
• The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 8,537,242 - Host interface for imaging arrays

Issued September 17, 2013

The Invention Explained

• Problem Addressed: The patent addresses the same problem as its parent '790 patent: the incompatibility between image sensor data output and standard microprocessor interfaces, which requires costly and complex external circuitry ('242 Patent, col. 1:43-52).
• The Patented Solution: The '242 patent claims a method for performing the functions of the interface system. The claimed method involves the steps of receiving image data from an imaging array, storing that data in a FIFO memory, using a counter to track the amount of data in the memory, comparing that count against a predetermined limit, and based on that comparison, generating an interrupt signal to prompt a processor to transfer the stored data ('242 Patent, Abstract; col. 8:55-67).
• Technical Importance: By claiming the operational method, the patent provides a different form of protection for the core inventive concept, focusing on the sequence of actions for managing the data flow rather than the physical apparatus itself ('242 Patent, col. 1:62-67).

Key Claims at a Glance

• The complaint alleges infringement of exemplary claims from the patent without specifying them (Compl. ¶21). Independent claim 1 is representative of the patented method:
  • A method of processing imaging signals, the method comprising:
  • receiving image data from an imaging array;
  • storing the image data in a FIFO memory;
  • updating a FIFO counter to maintain a count of the image data in the FIFO memory in response to memory reads and writes;
  • comparing the count of the FIFO counter with a FIFO limit;
  • generating an interrupt signal to request a processor to transfer image data from the FIFO memory...; and
  • transferring image data from the FIFO memory to the processor in response to the interrupt signal.
• The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

Product Identification

The complaint asserts infringement by "Exemplary Defendant Products" that are identified in claim charts attached as Exhibits 3 and 4 (Compl. ¶12, ¶21). As these exhibits were not filed with the complaint, the specific accused products are not identified in the provided document.

Functionality and Market Context

The complaint alleges that the accused products "practice the technology claimed" by the patents-in-suit (Compl. ¶17, ¶26). This suggests the products are alleged to be, or contain, imaging systems or components that buffer data between an image sensor and a processor. The complaint further alleges that Defendant sells these products to customers for use in "end-user products" (Compl. ¶16, ¶25). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint references claim chart exhibits that were not provided with the public filing (Compl. ¶18, ¶27). The infringement theory is therefore summarized from the complaint's narrative allegations.

For the ’790 Patent, the complaint alleges that the Defendant's products directly infringe by incorporating all elements of the asserted claims. The narrative theory is that the accused products contain an "interface" with a "memory" (e.g., a buffer) that stores data from an image sensor, a "signal generator" that creates a signal based on the amount of data in that memory, and a "circuit" that controls the data transfer to a processor at the processor's rate (Compl. ¶12, ¶17).

For the ’242 Patent, the complaint alleges that the Defendant's products directly infringe by performing the claimed method steps. The narrative theory is that in their operation, the products receive and store image data, update a count of that data, compare the count to a limit, and generate a processor request signal as a result, thereby carrying out the patented method (Compl. ¶21, ¶26).

Identified Points of Contention

• Architectural Questions: A potential point of dispute may be whether the architecture of the accused products maps onto the elements of the asserted claims. For instance, questions may arise as to whether the products contain a distinct "interface" as claimed, or if the alleged functions are performed by a more deeply integrated system-on-a-chip (SoC) in a manner that does not align with the claim structure.
• Technical Questions: A key technical question will likely concern the trigger for processor communication. The complaint's theory requires evidence that the accused products' processor alert signal is generated specifically "in response to the quantity of data in the memory" ('790 Patent) or by "comparing the count... with a FIFO limit" ('242 Patent). The case may turn on whether the accused devices' signaling is causally linked to the buffer's fill level or is triggered by other, more general system events.

V. Key Claim Terms for Construction

• The Term: "interface" ('790 Patent, Claim 1)

  • Context and Importance: The definition of "interface" is central to the scope of the apparatus claims. Its construction will determine whether the term requires a physically distinct component or can be read more broadly to cover a set of functions within a larger integrated circuit. Practitioners may focus on this term because the defendant could argue for a narrow, structural definition based on the patent's diagrams, while the plaintiff may advocate for a broader, functional definition.
  • Intrinsic Evidence for a Broader Interpretation: The Summary of the Invention describes the invention functionally as "an interface for receiving data... and for transferring the data," which may support a construction not tied to a specific physical structure ('790 Patent, col. 2:4-6).
  • Intrinsic Evidence for a Narrower Interpretation: The detailed description repeatedly illustrates the interface as a discrete block (element 13 in FIG. 2) containing specific sub-components. The specification also emphasizes the benefit of integrating the interface "on the same die as the imaging array sensor," which could be argued to limit the term to on-chip structures with a similar arrangement ('790 Patent, col. 2:29-31).

• The Term: "in response to the quantity of data in the memory" ('790 Patent, Claim 1)

  • Context and Importance: This phrase defines the causal link required for infringement. The infringement analysis for the signal generator element will depend on whether the accused products generate an alert because of the amount of data in a buffer.
  • Intrinsic Evidence for a Broader Interpretation: The patent describes a specific embodiment where an "interrupt generator compares the FIFO counter output Sc and the FIFO limit S₁" ('790 Patent, col. 6:11-13). This language could support a construction that covers any threshold-based triggering mechanism responsive to data volume.
  • Intrinsic Evidence for a Narrower Interpretation: A party could argue that the phrase requires more than a simple temporal relationship; it requires that the "quantity of data" is the direct input controlling the signal generation. A system that sends a status signal after every data write, for example, might be argued not to be responding to the quantity of data but simply to the write event itself.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement. This allegation is based on the assertion that, at least after being served with the complaint, Defendant had knowledge of the patents and continued to sell the accused products while distributing "product literature and website materials" that allegedly instruct customers and end-users on how to operate the products in an infringing manner (Compl. ¶15-16, ¶24-25).
• Willful Infringement: The complaint alleges that service of the complaint itself provides "Actual Knowledge of Infringement" and that Defendant's continued infringing activities thereafter are done despite this knowledge (Compl. ¶14-15, ¶23-24). While the complaint does not use the word "willful," these allegations form the basis for a claim of post-suit willful infringement and a request for enhanced damages under 35 U.S.C. § 284 and a finding that the case is "exceptional" under § 285 (Compl. p. 6-7, ¶F, ¶G.i).

VII. Analyst’s Conclusion: Key Questions for the Case

The resolution of this dispute may depend on the court's answers to several central questions:

• A primary issue will be one of architectural mapping: can the claimed elements of an "interface," "memory," and "signal generator" be discretely identified within the accused products' potentially highly integrated circuitry, or does the products' design differ in a way that avoids a one-to-one correspondence with the claim limitations?
• A key evidentiary question will be one of functional causation: does the plaintiff's evidence demonstrate that the accused devices generate processor alerts specifically "in response to the quantity of data" in a buffer, as required by the claims, or are the alerts triggered by other system-level events unrelated to the buffer's fill state?
• Finally, the assertion of a method patent raises a question of infringement locus: does the defendant, by making and selling the accused products, perform every step of the asserted method claims from the '242 patent, or could certain steps be considered performed only by the end-user, potentially raising issues of divided infringement?