DCT

1:25-cv-11061

Guangdong Willing Technology Corp v. Shenzhen Hongfa Dianzi Shangwu Youxian Gongsi

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-11061, N.D. Ill., 09/12/2025
  • Venue Allegations: Plaintiff alleges venue is proper because Defendant is a foreign entity not resident in the United States and has committed acts of infringement in the district by selling products through interactive online marketplaces.
  • Core Dispute: Plaintiff alleges that Defendant’s flexible food warming mats infringe a patent related to the construction of flexible heating boards with encapsulated heating wires.
  • Technical Context: The technology involves flexible, portable electric heating pads, typically made of silicone, designed to keep food warm and be easily stored by rolling up.
  • Key Procedural History: The patent-in-suit is identified as a continuation of a prior U.S. application and claims priority to a Chinese patent application. No other litigation, licensing history, or administrative proceedings are mentioned in the complaint.

Case Timeline

Date Event
2023-04-27 '244 Patent Priority Date (via CN 202321013145.6)
2024-04-26 Filing Date of Parent Application (U.S. App. No. 18/646,924)
2024-11-07 '244 Patent Application Filing Date
2025-07-01 '244 Patent Issue Date
2025-09-12 Complaint Filing Date

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

U.S. Patent No. 12,349,244 - "FLEXIBLE HEAT PRESERVATION BOARD WITH HEATING WIRE ENCAPSULATED THEREIN"

The Invention Explained

  • Problem Addressed: The patent’s background section identifies a need for food heating devices that can be easily stored, noting that most existing devices are made of rigid materials like metal or glass, which occupy significant space (’244 Patent, col. 2:21-24). It also notes the general problem of keeping dishes warm during a meal to preserve taste and quality (’244 Patent, col. 1:21-34).
  • The Patented Solution: The invention is a flexible heat preservation board comprising a heating pad, a heating wire, and a liquid adhesive (’244 Patent, Abstract). The heating pad, made of a flexible material, features a winding groove on one side to house the heating wire. Within this groove, two opposing protrusions run along its length, creating a narrow opening that is smaller than the diameter of the heating wire. This structure mechanically holds the wire in place. A liquid adhesive is then used to fill the groove, encapsulating the wire and protrusions to secure the assembly (’244 Patent, col. 3:29-42; Fig. 2). The entire board, including the pad and wire, is flexible, allowing it to be rolled for storage (’244 Patent, col. 2:33-35).
  • Technical Importance: The claimed construction provides a flexible heating device that addresses the storage and portability limitations of prior rigid heating plates (’244 Patent, col. 4:21-26).

Key Claims at a Glance

  • The complaint asserts infringement of independent claim 1 and dependent claims 2-7 (Compl. pp. 5-9, 10-14, etc.).
  • Independent Claim 1 requires:
    • A flexible heat preservation board comprising a heating pad, a heating wire, and a liquid adhesive.
    • The heating pad has a first side with a groove in a winding pattern and a plurality of projections of equal height.
    • The groove has a first inner surface with a first protrusion and a second inner surface with a second protrusion, where the protrusions face each other.
    • A distance between the edges of the protrusions is less than the diameter of the heating wire, creating an open space to receive the wire.
    • Gaps are formed between the lower surfaces of the protrusions and the outer surfaces of the heating wire.
    • The liquid adhesive encapsulates the protrusions and the heating wire within the groove.
    • Both the heating pad and the heating wire are flexible.

III. The Accused Instrumentality

Product Identification

The complaint identifies multiple accused products, including "Food Warming Mat - Fast Heating Silicone Electric Warming Tray with 4 Level Temperature, Raised Feet Protects Table, Roll Up Buffet Hot Plates Heat Pad, Portable Food Warmer for Parties Home Travel" and functionally identical products with slightly different marketing names (Compl. ¶18; pp. 4, 10, 15, 21).

Functionality and Market Context

The accused products are described as flexible, roll-up silicone warming mats that provide fast and even heating for keeping food warm (Compl. p. 10). They are marketed for home, buffet, and party use. The complaint includes a visual depicting the product rolled up for storage, illustrating its flexibility (Compl. p. 5). Another visual highlights that the product has "Thickened Feet" to protect the underlying table surface, which Plaintiff alleges corresponds to the claimed "projections" (Compl. p. 6). The products are sold through online marketplaces and target consumers in the United States (Compl. ¶11).

IV. Analysis of Infringement Allegations

Claim Chart Summary

The complaint provides claim charts in the form of side-by-side comparisons of claim text and product images. The following table summarizes the allegations for the lead independent claim.

U.S. Patent No. 12,349,244 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a heating pad, provided with a power supplier, wherein a first side of the heating pad is defined with a groove, the groove is arranged in a winding pattern... The accused product is a flexible silicone heating pad with a power supplier and an internal heating element arranged in a winding pattern. A visual provided in the complaint contrasts the alleged winding pattern of the accused product ("Ours") with that of competing products ("Others"). (Compl. p. 5) ¶16; p. 5 col. 5:1-5
...and the first side of the heating pad is also arranged with a plurality of projections having an equal height; The accused product has raised feet on its underside, alleged to be the claimed "projections." A detail image shows these features and describes them as "Thickened Feet Radiating Heat Better & Anti-scald." (Compl. p. 6) ¶16; p. 6 col. 5:1-5
a heating wire, wherein both ends of the heating wire are connected to the power supplier; and The product contains an internal heating wire connected to a power source, as depicted in diagrams showing heat rising from the mat. ¶16; p. 5 col. 5:6-8
a liquid adhesive; The complaint alleges the presence of a liquid adhesive but provides no specific evidence beyond a textual assertion. ¶16; p. 5 col. 5:9
wherein a first inner surface of the groove is provided with a first protrusion, a second inner surface of the groove is provided with a second protrusion...[defining specific geometry] The complaint alleges this internal structure exists within the accused product but supports the allegation with high-level marketing diagrams of heat flow rather than a cross-section or technical depiction of the groove's internal geometry. ¶16; p. 6 col. 5:10-20
the liquid adhesive encapsulates the first protrusion, the second protrusion, and the heating wire in the groove; and both the heating pad and the heating wire are flexible. The accused product is shown to be flexible and rollable. Encapsulation is asserted based on the product's construction. ¶16; pp. 5, 6 col. 5:17-22

Identified Points of Contention

  • Evidentiary Question: The complaint's infringement theory relies heavily on the claimed internal geometry of the groove, including the dual-protrusion structure and the encapsulating liquid adhesive. A central question will be what evidence exists that the accused products, beneath their surface, actually embody this specific micro-structure as required by the claim, as the complaint's visual evidence consists of marketing illustrations rather than technical tear-downs or cross-sections.
  • Scope Question: A dispute may arise over whether the "plurality of projections having an equal height" on the "first side" of the heating pad reads on the "Thickened Feet" shown on the underside of the accused product (Compl. p. 6). The interpretation will depend on whether the "first side" (defined as the side with the groove) is considered the top or bottom surface of the device.

V. Key Claim Terms for Construction

The Term: "liquid adhesive"

  • Context and Importance: This is a required component of the claimed invention. The infringement analysis depends on whether the accused product's method of securing the heating wire involves a "liquid adhesive" as that term is understood in the context of the patent. Practitioners may focus on this term because the complaint provides no direct evidence of its presence, and manufacturing alternatives like overmolding the silicone pad material might not meet a narrow definition of "adhesive."
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification states that "liquid silicone is selected to encapsulate the heating wire" (’244 Patent, col. 2:61-62). Plaintiff may argue that if the heating pad is made of silicone, and additional liquid silicone is used to fill the groove and cure, this meets the claim limitation, even if part of a single manufacturing process.
    • Evidence for a Narrower Interpretation: The patent consistently treats the "heating pad 10," "heating wire 20," and "liquid adhesive 50" as distinct components of the invention (’244 Patent, col. 2:27-28, Fig. 1). A defendant could argue this implies a chemically or structurally distinct substance applied as a bonding agent, rather than more of the same material used to form the pad itself in an overmolding process.

The Term: "a first protrusion" and "a second protrusion" that "face each other"

  • Context and Importance: The specific geometry of these two protrusions, which create a narrow opening to mechanically grip the heating wire, is a key structural limitation of claim 1. Infringement requires showing that the accused products contain this specific internal structure, not just a simple channel for the wire.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes the function of the protrusions as providing a "limiting structure" and achieving an "effective fixation effect on the heating wire" (’244 Patent, col. 3:5, col. 3:27-28). Plaintiff may argue that any internal groove features that serve this wire-retention function meet the spirit of the claim.
    • Evidence for a Narrower Interpretation: Claim 1 recites a highly specific arrangement: a protrusion on a "first inner surface" and another on a "second inner surface" that "face each other," with a "distance between a first edge... and a second edge" that is "less than a diameter of the heating wire" (’244 Patent, col. 5:10-14). A defendant will likely argue that this language requires a precise, two-part gripping structure, and the complaint offers no evidence to show the accused products contain this specific geometry.

VI. Other Allegations

Indirect Infringement

The complaint includes a general allegation of direct and/or indirect infringement (Compl. ¶18) but does not plead specific facts to support claims for induced or contributory infringement, such as references to user manuals or instructions that would encourage infringing acts.

Willful Infringement

Willfulness is alleged based on Defendant "knowingly and willfully" making or selling infringing products (Compl. ¶12). The complaint notes that infringers like the Defendant "continue operation despite the Plaintiff’s enforcement efforts, such as take-down notices," which may serve as a basis for alleging pre-suit knowledge of the patent or infringement (Compl. ¶13).

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

  • A core issue will be one of evidentiary proof: does the internal construction of the accused flexible mats feature the specific dual-protrusion geometry and distinct "liquid adhesive" encapsulation as recited in claim 1? The case may depend on technical discovery, such as product teardowns, to resolve the discrepancy between the claim’s detailed requirements and the complaint’s use of high-level marketing visuals.
  • A secondary issue will be one of claim construction: can the term "liquid adhesive" be construed to cover a manufacturing process where the silicone material of the heating pad itself is used to encapsulate the wire (i.e., overmolding), or does it require a chemically distinct bonding agent applied in a separate step?