1:26-cv-07157
Jiandeshi Jiaqian Maoyi Youxianzeren Gongsi v. North Star Home LLC
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Jiandeshi Jiaqian Maoyi Youxianzeren Gongsi, Jiandeshi Chutiange Maoyiyouxian Gongsi, and Jiandeshi Yaowei Maoyiyouxian Gongsi (People's Republic of China)
- Defendant: North Star Home LLC (Illinois)
- Plaintiff's Counsel: YoungZeal LLP
- Case Identification: 1:26-cv-07157, N.D. Ill., 06/18/2026
- Venue Allegations: Venue is alleged to be proper as Defendant maintains a regular and established place of business within the Northern District of Illinois.
- Core Dispute: Plaintiffs seek a declaratory judgment that their electric-blanket products do not infringe U.S. Patent No. 12,219,672, and/or that the patent is invalid, following a prior infringement action filed by the Defendant that was subsequently dismissed without prejudice.
- Technical Context: The technology concerns safety circuits for electric blankets, designed to prevent fires or electrical hazards by precisely controlling temperature and detecting component faults.
- Key Procedural History: This action follows a prior lawsuit filed by Defendant North Star Home LLC against the current Plaintiffs on October 20, 2025, alleging infringement of the same patent. That case was voluntarily dismissed by North Star Home LLC without prejudice on November 21, 2025. Plaintiffs initiated this declaratory judgment action, asserting that the prior litigation and lack of assurance against re-filing create a substantial and immediate controversy.
Case Timeline
| Date | Event |
|---|---|
| 2021-08-18 | '672 Patent Priority Date |
| 2021-11-03 | '672 Patent Application Filing Date |
| 2024-08-30 | '672 Patent assigned from inventor to Ningbo Owfine Home Textiles Design Co., Ltd. |
| 2024-08-30 | '672 Patent assigned from Ningbo Owfine Home Textiles Design Co., Ltd. to North Star Home LLC |
| 2024-09-03 | Assignment to North Star Home LLC recorded |
| 2025-02-04 | '672 Patent Issue Date |
| 2025-10-20 | Prior infringement action filed by Defendant against Plaintiffs |
| 2025-11-20 | Defendant filed notice of voluntary dismissal in prior action |
| 2025-11-21 | Prior action dismissed without prejudice |
| 2026-06-18 | Complaint for Declaratory Judgment filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 12,219,672 - "Safe heating circuit and electric blanket provided with safe heating circuit"
- 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 Invention Explained
- Problem Addressed: The patent's background identifies the risk of fire or electric leakage in electric blankets, which can occur from inaccurate temperature control or the aging of key components, leading to dangerous short-circuits or open-circuits that are not detected in time to cut power '672 Patent, col. 1:20-33
- The Patented Solution: The invention is a safety circuit that aims to solve this problem by using a dual-mode temperature monitoring system. It employs a Positive Temperature Coefficient (PTC) heating element for primary heating and a Negative Temperature Coefficient (NTC) element to detect leakage currents, which can indicate local overheating '672 Patent, col. 1:36-44 A central controller monitors voltage signals from two separate acquisition circuits-one measuring the ground current of the PTC element and another measuring the leakage current via the NTC element-and compares them to a set point to precisely control a switching element and shut off power if a fault is detected '672 Patent, abstract '672 Patent, Fig. 1
- Technical Importance: The use of a PTC heating element combined with a separate NTC-based leakage detection circuit provides a multi-layered approach to safety, intended to be more robust than single-point temperature monitoring systems '672 Patent, col. 1:36-44 '672 Patent, col. 3:61-4:4
Key Claims at a Glance
- The complaint identifies independent claims 1 and 16 as representative Compl. ¶13 Compl. ¶15 Compl. ¶25
- Independent Claim 1 recites a safe heating circuit comprising:
- A PTC electric heating element.
- A first switching element, coupled into a ground loop of the PTC element and configured to switch a power loop of the PTC element.
- A first voltage acquisition circuit to sample a first temperature voltage based on the ground current of the PTC element.
- An NTC element disposed between the PTC element and a sensing element.
- A sensing element to receive a leakage current transmitted by the NTC element.
- A second voltage acquisition circuit to sample a second temperature voltage based on the leakage current.
- A controller to compare either the first or second temperature voltage to a set temperature voltage and output an on-off control signal.
- Independent Claim 16 recites an electric blanket that incorporates the safe heating circuit of claim 1 Compl. ¶15
- The complaint notes that claims 2-15 and 17 are dependent claims Compl. ¶14 Compl. ¶16
III. The Accused Instrumentality
Product Identification
- The "Accused Products" are electric-blanket products sold by the Plaintiffs through their Amazon storefronts: "Warm Soft Home," "Chutiange," and "Jiande Yaowei Trading Co., Ltd." Compl. p.2 Compl. ¶17
Functionality and Market Context
- The complaint does not describe the functionality of the Accused Products in detail. Instead, it focuses on what the products allegedly lack. The action arises from Defendant's prior allegations that these products, sold under various ASINs on Amazon, embodied the patented technology Compl. ¶17 The prior lawsuit sought to disable Plaintiffs' online listings, indicating the products are commercially available through online marketplaces Compl. ¶18
IV. Analysis of Infringement Allegations
This declaratory judgment action alleges non-infringement. The complaint provides a table summarizing claim elements that are allegedly missing from the Accused Products Compl. ¶26 The complaint includes a block diagram from the '672 Patent, illustrating the relationship between the PTC heating element, the first and second voltage acquisition circuits, and the controller Compl. ¶11
'672 Patent Non-Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| [1.b] a first switching element, coupled into a ground loop of the PTC electric heating element and configured to switch on or off a power loop of the PTC electric heating element based on an on-off control signal | The complaint alleges that the Accused Products do not include this element. | ¶26 | col. 5:14-19 |
| [1.g] a controller, configured to compare the first temperature voltage or the second temperature voltage to a set temperature voltage and output the on-off control signal based on a comparison result | The complaint alleges that the Accused Products do not include a controller that performs this function. | ¶26 | col. 5:26-30 |
- Identified Points of Contention:
- Technical Questions: The central dispute is factual: do the Accused Products contain a circuit that meets the limitations of claims 1 and 16? The court will need to resolve whether the products' circuitry includes a switching element "coupled into a ground loop" and a controller performing the specific comparison logic recited in the claim. This will likely require expert testimony and analysis of the products' hardware and software.
- Scope Questions: The non-infringement argument raises the question of whether the Accused Products' temperature regulation system, if one exists, operates in a fundamentally different way from the patented method. For example, does the accused controller use a different input or a different logical process to regulate heat, thereby falling outside the scope of the "compare" limitation?
V. Key Claim Terms for Construction
The Term: "coupled into a ground loop" (from claim 1(b))
Context and Importance: Plaintiffs allege the "first switching element" is entirely absent, which may turn on the definition of its location Compl. ¶26 Practitioners may focus on this term because the specific placement of the switching element in the "ground loop" is a precise architectural choice detailed in the patent. The infringement analysis may hinge on whether the accused products' switching component, if any, is located in the part of the circuit that would be considered the "ground loop."
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification notes that "coupled" includes both direct and indirect connections, which could be argued to encompass a wider range of circuit configurations '672 Patent, col. 5:1-9
- Evidence for a Narrower Interpretation: The figures and detailed description consistently show the first switching element (T1) providing the final path to the "power ground" (17) '672 Patent, Fig. 2 '672 Patent, col. 5:40-42 This specific topology could support an argument that "coupled into a ground loop" requires the switch to be in this precise part of the circuit.
The Term: "compare" (from claim 1(g))
Context and Importance: Plaintiffs allege the controller function is missing Compl. ¶26 The definition of "compare" is critical to determining whether the accused controller's logic performs the claimed function. The dispute may focus on whether the accused controller's decision-making process is equivalent to a direct comparison of a sampled temperature voltage to a set voltage.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party could argue that "compare" should be given its ordinary meaning, covering any logical operation where an input voltage influences a control output, even if not a direct numerical comparison.
- Evidence for a Narrower Interpretation: The specification describes a specific working principle where the controller detects if a "sampling voltage is lower than the set temperature voltage" and then acts accordingly '672 Patent, col. 7:15-24 This detailed operational description may be used to argue that "compare" requires this specific threshold-based decision logic.
VI. Other Allegations
- Indirect Infringement: The complaint seeks a declaratory judgment that Plaintiffs have not contributed to or induced infringement of the '672 Patent Compl. ¶24 No specific facts are alleged beyond a general denial of any infringing activity.
- Willful Infringement: The complaint makes no allegations of willfulness.
VII. Analyst's Conclusion: Key Questions for the Case
This declaratory judgment action appears to center on three primary questions for the court:
A Factual and Evidentiary Question: Do the accused electric blankets, as sold, contain the circuit components and logic claimed in the '672 Patent? The case will likely depend on technical evidence and expert analysis to determine if the products possess a "first switching element coupled into a ground loop" and a "controller" that performs the claimed comparison, as alleged by the patentee in the prior litigation and denied by the DJ-Plaintiffs here.
A Claim Construction Question: What is the proper scope of key claim limitations? The outcome may turn on the court's construction of terms like "coupled into a ground loop" and the functional requirement that the controller "compare" specific voltages, which will define the boundary between the patented invention and non-infringing alternative safety circuits.
An Invalidity Question: Are the asserted claims of the '672 Patent invalid as anticipated or obvious in light of the prior art? The complaint identifies four specific prior art references, suggesting that even if the products are found to infringe, the Plaintiffs will mount a significant challenge to the patent's validity under 35 U.S.C. §§ 102 and/or 103 Compl. ¶¶31-33