DCT

2:14-cv-09815

GoTo Denshi Co Ltd v. Mitsubishi Cable Industries Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:14-cv-09815, C.D. Cal., 12/23/2014
  • Venue Allegations: Venue is alleged to be proper based on Defendants’ business activities in the Central District of California and the occurrence of a substantial part of relevant events in the district.
  • Core Dispute: Plaintiffs allege that Defendants’ MEXCEL brand square wire products infringe a patent related to the specific geometry of wire used for electrical coils.
  • Technical Context: The technology concerns specialized conductive wires for creating compact, high-performance electrical coils, which are fundamental components in electronics such as audio speakers.
  • Key Procedural History: While this complaint was filed in December 2014, a subsequent Inter Partes Review (IPR) proceeding (IPR2015-01108) was initiated against the patent-in-suit. The resulting IPR certificate, issued January 11, 2019, indicates that all claims of the patent (claims 1-8) have been cancelled. This post-filing event is likely dispositive of the infringement action.

Case Timeline

Date Event
2003-11-13 ’888 Patent Priority Date
2007-07-03 ’888 Patent Issue Date
2014-12-23 Complaint Filing Date
2015-04-24 IPR against ’888 Patent Filed (IPR2015-01108)
2019-01-11 IPR Certificate Issued Cancelling All Claims of ’888 Patent

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

  • Patent Identification: U.S. Patent No. 7,238,888, Wire For Coil, issued July 3, 2007.

The Invention Explained

  • Problem Addressed: The patent describes drawbacks of prior art coil wires. Conventional round wires create gaps when wound into a coil, resulting in a low "packing factor" and inefficient use of space. Conversely, wires with a perfect square cross-section, while packing tightly, make it difficult to apply a uniform insulating layer, especially at the sharp corners, which can lead to manufacturing defects and insulation failure. (ʼ888 Patent, col. 1:10-21, 1:28-36).
  • The Patented Solution: The invention proposes a wire with a generally square cross-section but with specially dimensioned "chamfers" (beveled or rounded corners). The solution is not merely adding chamfers, but defining their geometry through specific mathematical relationships. The wire's cross-sectional area must be at least 1.15 times that of a reference circle, or its outer circumference must be at least 1.09 times that of the reference circle, where the circle's diameter is equal to the length of one side of the wire's base square. (ʼ888 Patent, col. 2:11-15, 2:28-34). This design is intended to optimize the trade-off between maximizing the packing factor and ensuring a stable, uniform insulating layer can be applied. (ʼ888 Patent, col. 2:50-59).
  • Technical Importance: This approach seeks to enable the production of higher-performance coils with improved packing density and heat radiation, at a cost and with productivity comparable to that of conventional round wire coils. (ʼ888 Patent, col. 2:61-68).

Key Claims at a Glance

  • The complaint asserts "one or more claims" without specifying which ones (Compl. ¶11). The patent’s independent claims are 1 and 3.
  • Independent Claim 1:
    • A wire for use in a coil, said wire having a square sectional shape,
    • wherein chamfers are provided at four corners in the section of the square, and
    • sectional area of said wire having the chamfers is at least 1.15 times as large as that of a circle having a diameter which is the same as the length of one side of said square.
  • Independent Claim 3:
    • A wire for use in a coil, said wire having a square sectional shape,
    • wherein chamfers are provided at four corners in the section of the square, and
    • overall length of an outer circumference of the section of said wire having said chamfers is at least 1.09 times as long as circumference of a circle having a diameter which is the same as the length of one side of said square.
  • The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

  • Product Identification: The accused products are identified as "the MEXCEL square wire products" (Compl. ¶11).
  • Functionality and Market Context: The complaint alleges these are products "covered by the claims of the '888 patent" but provides no specific technical details about their construction, materials, or dimensions (Compl. ¶11). The allegation is limited to the act of making, using, selling, or importing these products within the United States (Compl. ¶11). No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide sufficient detail for a tabular claim chart analysis. It alleges in a conclusory manner that the MEXCEL products are "covered by the claims of the ʼ888 patent" (Compl. ¶11). The infringement theory is based on the general allegation that Defendants make, use, sell, or import these "square wire products" (Compl. ¶11).

  • Identified Points of Contention:
    • Evidentiary Question: A central issue for infringement would be whether Plaintiffs can produce evidence demonstrating that the accused MEXCEL products meet the precise mathematical limitations of the claims. For example, what evidence establishes that the product's cross-sectional area is "at least 1.15 times as large" as the specified reference circle, as required by claim 1?
    • Technical Question: The complaint does not specify whether the accused "square wire products" possess the "chamfers" required by all independent claims. The infringement analysis would depend on identifying such features and measuring their geometry to determine if they satisfy the claimed ratios.

V. Key Claim Terms for Construction

  • The Term: "sectional area of said wire" (from Claim 1)
  • Context and Importance: The determination of infringement hinges on a precise calculation of this area. Practitioners may focus on this term because its definition—whether it refers solely to the conductive core or includes the insulating layer—is critical. The patent's calculations and embodiments appear to focus on the conductive core, but ambiguity could form the basis of a dispute.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Narrower Interpretation (Conductor Only): The specification repeatedly distinguishes between the "wire (conductive part)" and the "insulating layer" that covers it (ʼ888 Patent, col. 3:62-65). Furthermore, the detailed description of embodiments calculates area and circumference ratios based on the dimensions of the conductive core before an insulating layer is applied (ʼ888 Patent, col. 5:16-25, col. 6:1-14).
    • Evidence for a Broader Interpretation (Conductor + Insulator): The preamble of the claim refers to "A wire for use in a coil," which in a final, usable form would include insulation. An argument could be made that the "wire" as a whole, ready for use, is what is being claimed.
  • The Term: "square sectional shape" (from Claims 1 and 3)
  • Context and Importance: This term defines the baseline geometry for the claim's mathematical ratios. The degree to which the base shape must conform to a perfect square to meet this limitation will be a key question.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Narrower Interpretation (A Perfect Square): The patent consistently refers to a "square 3" as the "base of creation of the wire" and calculates dimensions from that starting point (ʼ888 Patent, col. 3:39-42, Fig. 5). The description explicitly states that the invention does not include a "complete square" because of issues with applying insulation to sharp corners (ʼ888 Patent, col. 4:11-15), implying the base is a true square from which chamfers are created.
    • Evidence for a Broader Interpretation (A Substantially Square Shape): A defendant might argue that in manufacturing, perfect geometric shapes are impossible and the term should be construed more broadly to mean "substantially square." However, the patent's own text, which relies on precise calculations derived from a square, may weigh against such a construction.

VI. Other Allegations

  • Indirect Infringement: The complaint makes a conclusory allegation of inducing and contributory infringement without providing any specific supporting facts, such as identifying instructions, manuals, or specific acts of encouragement (Compl. ¶11).
  • Willful Infringement: The complaint alleges that Defendants' infringement is "willful," but it does not plead any facts to support this claim, such as allegations of pre-suit knowledge of the patent or a deliberate scheme to copy the invention (Compl. ¶13).

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

  1. Viability of the Action: The most critical issue is the legal status of the asserted patent. Given that an IPR proceeding subsequent to the complaint’s filing resulted in the cancellation of all claims of the ʼ888 Patent, a primary question is whether the lawsuit has any remaining legal basis. The cancellation effectively renders the patent unenforceable.
  2. Evidentiary Proof of Infringement: Had the patent remained valid, a key question would be one of evidentiary proof. The claims are defined by precise mathematical ratios (e.g., a sectional area "at least 1.15 times" a reference area). The case would turn on whether Plaintiff could produce technical evidence, likely from reverse engineering or discovery, proving that the accused MEXCEL products meet these specific quantitative thresholds.