DCT

1:25-cv-12800

North Star Home LLC v. Jiandeshi Jiaqian Maoyi Youxianzeren Gongsi

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-12800, N.D. Ill., 10/20/2025
  • Venue Allegations: Plaintiff alleges venue is proper because a substantial part of the events giving rise to the claim occurred in the district, Defendants have significant contacts through business activities targeting the district, and Defendants are foreign entities who may be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendants’ electric blanket products infringe a patent related to a safe heating circuit design that uses dual temperature sensing mechanisms for improved safety and control.
  • Technical Context: The technology concerns safety circuits for consumer heating appliances, a field where preventing overheating, fires, and electrical leakage is a primary design consideration.
  • Key Procedural History: The complaint does not mention any prior litigation, licensing history, or post-grant proceedings related to the patent-in-suit.

Case Timeline

Date Event
2021-08-18 U.S. Patent No. 12,219,672 Priority Date
2025-02-04 U.S. Patent No. 12,219,672 Issue Date
2025-10-20 Complaint Filing Date

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

  • Patent Identification: U.S. Patent No. 12,219,672, "Safe Heating Circuit and Electric Blanket Provided with Safe Heating Circuit," issued February 4, 2025 (the "’672 Patent").

U.S. Patent No. 12,219,672 - "Safe Heating Circuit and Electric Blanket Provided with Safe Heating Circuit"

The Invention Explained

  • Problem Addressed: The patent’s background section describes the safety risks associated with conventional electric blankets, such as electric leakage or fire. These hazards can arise from inaccurate temperature control or the aging of key components, which may lead to short circuits or open circuits that cause localized overheating that is not detected in time to shut off power. (’672 Patent, col. 1:20-32).
  • The Patented Solution: The invention is a safe heating circuit that employs a dual-mode temperature control and fault detection system. It uses a Positive Temperature Coefficient (PTC) electric heating element, whose resistance increases as it gets hotter, providing a self-regulating effect. A controller monitors temperature and faults through two distinct mechanisms: (1) a first voltage acquisition circuit that samples a ground current from the PTC element, and (2) a second voltage acquisition circuit that samples a "leakage current" transmitted from the PTC element through a Negative Temperature Coefficient (NTC) element to a separate "sensing element." (’672 Patent, col. 1:47-62; Fig. 1). By comparing voltage measurements from these two paths to set values, the controller can precisely regulate temperature and detect fault conditions like open or short circuits. (’672 Patent, col. 7:7-62).
  • Technical Importance: This dual-sensing approach (PTC ground current and NTC leakage current) provides a more robust and precise method for temperature control and fault detection than systems relying on a single sensor. (’672 Patent, col. 4:61-64).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 2, 4, 5, 6, 13, 16, and 17. (Compl. ¶11).
  • Independent Claim 1 requires:
    • A PTC electric heating element that generates heat.
    • A first switching element, coupled into a ground loop of the PTC element, to switch a power loop on or off.
    • A first voltage acquisition circuit to sample a first temperature voltage based on the PTC element's ground current.
    • An NTC element disposed between the PTC element and a sensing element.
    • The sensing element, configured to receive a leakage current from the PTC element transmitted by the NTC element.
    • A second voltage acquisition circuit to sample a second temperature voltage based on the leakage current.
    • A controller that compares one or both temperature voltages to a set voltage and outputs an on-off control signal.
  • The complaint does not explicitly reserve the right to assert additional claims.

III. The Accused Instrumentality

Product Identification

The Accused Products are electric blankets offered for sale, sold, and shipped by Defendants through their interactive Amazon storefronts, including HomemateHero, Chutiange, and Jiande Yaowei Trading Co., Ltd. (Compl. ¶4, ¶9).

Functionality and Market Context

The complaint alleges that the Accused Products are "materially identical" and practice the "same heating-circuit design." (Compl. ¶10). It further alleges that these products "embody the patented safe-heating circuit technology" and "incorporate a heating-circuit design that infringes" the ’672 Patent. (Compl. ¶8, ¶22). The complaint does not provide further technical details regarding the specific operation of the accused circuits. It positions the products as being sold to U.S. consumers through e-commerce platforms. (Compl. ¶24).

IV. Analysis of Infringement Allegations

The complaint alleges that the Accused Products directly infringe at least Claim 1 and several dependent claims of the ’672 Patent. (Compl. ¶11, ¶30). The infringement theory is articulated at a high level, stating that Defendants make, use, sell, or import products that "embody the inventions claimed in the ’672 Patent." (Compl. ¶29). The complaint refers to an Exhibit D for more detailed infringement analysis, but this exhibit was not attached to the filed complaint. (Compl. ¶11, ¶22). Consequently, the complaint body itself does not contain a specific, element-by-element breakdown mapping features of the Accused Products to the limitations of the asserted claims.

No probative visual evidence provided in complaint.

V. Key Claim Terms for Construction

The Term: "a first switching element, coupled into a ground loop of the PTC electric heating element" (Claim 1)

  • Context and Importance: The location and nature of the switching element is a core architectural feature of the claimed circuit. Infringement may depend on whether an accused product's switching component is considered to be "coupled into a ground loop." A defendant might argue that a switch placed elsewhere in the circuit, such as on the high-voltage side, falls outside the scope of this limitation.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language uses the general term "switching element," which is not limited to a specific component type.
    • Evidence for a Narrower Interpretation: The specification consistently describes the first switching element as a "silicon-controlled rectifier element" (SCR) and depicts it in the ground path between the heating element and power ground. (’672 Patent, col. 1:62-65; Fig. 2). A defendant could argue this specific embodiment limits the claim's scope.

The Term: "a leakage current from the PTC electric heating element transmitted by the NTC element" (Claim 1)

  • Context and Importance: This limitation defines the second, NTC-based sensing mechanism. The dispute will likely center on the physical and electrical relationship required between the PTC, NTC, and sensing elements for a current to be considered a "leakage current... transmitted by the NTC element."
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The term "leakage current" is a general electrical term, and the parties may argue it should be given its plain and ordinary meaning without being tied to a specific physical structure.
    • Evidence for a Narrower Interpretation: The specification discloses a specific physical arrangement where the NTC element is a "material layer wrapping the electric heating wire" and the sensing element is a "sensing wire spirally wound on the NTC material layer." (’672 Patent, col. 12:1-12; Fig. 11). This integrated structure could be argued as necessary to practice the claimed "transmission" of a "leakage current."

VI. Other Allegations

  • Indirect Infringement: The complaint includes a conclusory allegation that Defendants' activities "may also constitute indirect infringement" but does not plead specific facts to support the requisite knowledge or intent for either induced or contributory infringement. (Compl. ¶30).
  • Willful Infringement: The complaint alleges that infringement is "willful and deliberate." (Compl. ¶32). The basis for this allegation is Defendants' alleged "anonymity and continued sales of the Accused Products despite Plaintiff’s patent rights," without asserting that Defendants had pre-suit knowledge of the ’672 Patent itself. (Compl. ¶32).

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

  • A primary issue will be one of claim construction, focusing on whether the specific circuit topology described in the patent limits the scope of the claims. The court's interpretation of terms like "coupled into a ground loop" and the required mechanism for transmitting a "leakage current" via the NTC element will be critical to the infringement analysis.
  • A central evidentiary question will be whether the accused electric blankets, upon technical inspection, actually implement the dual-sensing safety circuit claimed in the ’672 Patent. The complaint's general allegations of infringement will need to be substantiated with evidence showing that the accused products both monitor the PTC element's ground current and utilize a separate NTC-based leakage current sensor for temperature control and fault detection.