DCT

1:25-cv-15117

Zhuhai Shengchang Electric Co Ltd v. Zhuhai Demi Technology Co Ltd

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-15117, N.D. Ill., 12/12/2025
  • Venue Allegations: Venue is asserted on the basis that the defendants are not residents of the United States and have committed acts of infringement within the judicial district.
  • Core Dispute: Plaintiff alleges that Defendants’ various Dimmable LED Drivers infringe five U.S. patents related to LED power supply circuits and mechanical enclosures.
  • Technical Context: The technology at issue involves electronic drivers that control the power delivered to LED lights, enabling dimming functionality while addressing technical challenges like wide voltage compatibility, power efficiency, and flicker.
  • Key Procedural History: The complaint alleges that the numerous defendants, while presenting as separate online storefronts, are "alter egos of each other and confederates" acting in concert to sell infringing "knock-off" products. Plaintiff also states it has provided defendants with notice of infringement, forming the basis for a willfulness allegation.

Case Timeline

Date Event
2015-12-23 ’710 Patent Priority Date
2017-01-19 ’724 Patent Priority Date
2017-03-29 ’959 Patent Priority Date
2017-03-29 ’167 Patent Priority Date
2017-05-23 U.S. Patent No. 9,661,710 Issues
2018-04-10 U.S. Patent No. 9,942,959 Issues
2018-05-01 U.S. Patent No. 9,961,724 Issues
2018-07-31 U.S. Patent No. 10,039,167 Issues
2021-02-25 ’164 Patent Priority Date
2023-08-08 U.S. Patent No. 11,723,164 Issues
2025-12-12 Complaint Filing Date

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

U.S. Patent No. 9,661,710 - “Dimmer Holding Current Control Circuit for Phase Cut Dimming Power Supply”

  • Patent Identification: U.S. Patent No. 9,661,710, “Dimmer Holding Current Control Circuit for Phase Cut Dimming Power Supply,” issued May 23, 2017.

The Invention Explained

  • Problem Addressed: Conventional phase-cut dimming power supplies require a stable "holding current" to keep the dimmer's internal transistor in a conducting state. Prior methods to provide this current often result in high power consumption, excessive heat, and audible vibrations or noise from the dimmer. (’710 Patent, col. 1:15-40).
  • The Patented Solution: The patent discloses a specific control circuit designed to provide the necessary holding current with high stability and low power consumption. The circuit uses a field-effect transistor and a triode in a configuration that forms a stable current loop, limiting the current to a sufficient but not excessive level, thereby avoiding the heat and efficiency losses of prior art solutions. (’710 Patent, col. 3:1-26; Fig. 1).
  • Technical Importance: The invention aimed to improve the overall efficiency, reliability, and acoustic performance of dimmable LED power supplies, key factors for commercial adoption. (’710 Patent, col. 1:41-57).

Key Claims at a Glance

  • The complaint asserts independent claim 1. (Compl. ¶48).
  • Claim 1 requires a dimmer holding current control circuit comprising a specific combination of:
    • a rectifier diode I and a rectifier diode II
    • a field-effect transistor
    • a triode
    • a current-limiting resistance I and a current-limiting resistance II
    • a sampling resistance I and a sampling resistance II
    • a diode, a capacitance, and a resistance, all connected in a specific circuit topology. (’710 Patent, col. 4:27-60).

U.S. Patent No. 10,039,167 - “Phase-Cut Dimming Circuit with Wide Input Voltage”

  • Patent Identification: U.S. Patent No. 10,039,167, “Phase-Cut Dimming Circuit with Wide Input Voltage,” issued July 31, 2018.

The Invention Explained

  • Problem Addressed: Phase-cut dimming power supplies are typically designed for a narrow input voltage range, such as 90-130V for North America or 170-265V for Europe. This prevents a single product from being compatible with electrical grids worldwide. (’167 Patent, col. 1:26-34).
  • The Patented Solution: The invention describes a circuit that makes the dimming function independent of the input voltage's magnitude. It converts the chopped AC input from the dimmer into a low-frequency Pulse Width Modulation (PWM) signal. This signal is then processed by a "PWM signal conversion circuit" to generate a high-frequency PWM signal (>200 Hz) that controls the LED brightness without flicker. Because the duty cycle of the PWM signal is based on the phase cut of the input and not its voltage level, the circuit can operate over a wide input voltage range (e.g., 90-305V). (’167 Patent, col. 1:38-44, col. 3:1-10).
  • Technical Importance: This technology allows for the creation of universal dimmable LED drivers, simplifying manufacturing, logistics, and inventory for companies selling into global markets. (’167 Patent, col. 1:38-44).

Key Claims at a Glance

  • The complaint asserts independent claim 4. (Compl. ¶51).
  • Claim 4 requires a phase-cut dimming circuit comprising:
    • a first diode and a second diode
    • a first resistor, a second resistor, a third resistor, and a fourth resistor
    • a transistor
    • a photoelectric coupler
    • a PWM signal conversion circuit, all connected in a specific circuit arrangement. (’167 Patent, col. 8:36-64).

Multi-Patent Capsule: U.S. Patent No. 9,961,724 - “Phase-Cut Dimmable Power Supply with High Power Factor”

  • Patent Identification: U.S. Patent No. 9,961,724, “Phase-Cut Dimmable Power Supply with High Power Factor,” issued May 1, 2018.
  • Technology Synopsis: The patent addresses the problem of low power factor and high harmonic content in dimming power supplies, which can cause interference with the electrical grid. It discloses a system incorporating an active power factor correction (PFC) circuit along with a signal conversion circuit to provide efficient, high-quality power for dimmable LEDs. (’724 Patent, Abstract).
  • Asserted Claims: Independent claim 1 is asserted. (Compl. ¶54).
  • Accused Features: The complaint accuses the internal circuitry of the defendants' LED drivers, which allegedly includes active PFC and signal conversion functionalities that infringe the patent. (Compl. ¶55).

Multi-Patent Capsule: U.S. Patent No. 9,942,959 - “Phase-Cut Dimmable Power Supply with Wide Input Voltage”

  • Patent Identification: U.S. Patent No. 9,942,959, “Phase-Cut Dimmable Power Supply with Wide Input Voltage,” issued April 10, 2018.
  • Technology Synopsis: This patent, similar to the ’167 patent, targets the creation of a dimmable power supply with a wide input voltage range (90-305V). The disclosed solution uses an active PFC circuit, a power conversion circuit, and a wide input voltage dimming control circuit that generates a PWM signal to control the LED light, enabling compatibility with various global electrical standards. (’959 Patent, Abstract).
  • Asserted Claims: Independent claim 4 is asserted. (Compl. ¶57).
  • Accused Features: The accused features are the internal power conversion and wide-voltage dimming control circuits within the defendants' LED drivers. (Compl. ¶58).

Multi-Patent Capsule: U.S. Patent No. 11,723,164 - “Convenient Power Supply Box for Quick Parameter Adjustment”

  • Patent Identification: U.S. Patent No. 11,723,164, “Convenient Power Supply Box for Quick Parameter Adjustment,” issued August 8, 2023.
  • Technology Synopsis: This patent describes a mechanical enclosure for a power supply. The box body is partitioned into a first inner cavity for electronics (like a parameter-adjusting potentiometer) and a second inner cavity for wiring. The potentiometer's adjuster passes through a partition wall to be accessible from the wiring cavity, allowing for quick adjustments without opening the main electronics compartment. (’164 Patent, Abstract).
  • Asserted Claims: Independent claim 1 is asserted. (Compl. ¶96).
  • Accused Features: The physical housing of certain accused LED drivers, which are shown with integrated junction boxes that separate the main driver from the wiring area, are the accused features. (Compl. ¶97; Compl. p. 12, Image b).

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are various "Dimmable LED Drivers" sold by the defendants through numerous online storefronts on Amazon.com. (Compl. ¶¶ 38-39). The complaint includes images of several accused products, such as the "Dimmable LED Driver 24V 120W, 5-1 LE..." sold by defendant Shenzhenyoudianzikejiyouxiangongsi. (Compl. p. 11, Image a).

Functionality and Market Context

The accused products are power supplies that convert standard AC electrical current into a controlled DC current suitable for powering and dimming LED lights. (Compl. ¶¶ 5, 35). The complaint alleges that Plaintiff's engineers reverse-engineered twelve different purchased drivers and created circuit diagrams showing they possess "the same or substantially equivalent circuitry" to that which is patented. (Compl. ¶42). Several of the accused products feature metal enclosures with separate compartments for wiring, a design accused of infringing the ’164 patent. (Compl. p. 12, Image b). The complaint alleges these products are "unauthorized, and unlicensed knock-off" versions of Plaintiff's own drivers. (Compl. ¶34).

IV. Analysis of Infringement Allegations

The complaint references claim chart exhibits (Exhibits H-L) that were not provided with the filed complaint. (Compl. ¶44). The infringement theory is therefore based on the narrative allegations. Plaintiff alleges that its engineers "examined and tested the operation" of twelve purchased LED drivers and "found that each of the twelve dimmable LED Driver met all the limitations of at least one claim of the Asserted Patents." (Compl. ¶44). This finding is said to be based on reverse-engineered circuit diagrams that "fairly and accurately depict the circuitry" of the accused products. (Compl. ¶42).

  • Identified Points of Contention:
    • Circuit Patents (’710, ’167, ’724, ’959): A primary technical question will be whether the circuitry of the accused products, as reverse-engineered by the plaintiff, actually contains the specific components connected in the specific manner required by the asserted claims. The accuracy and interpretation of the plaintiff's reverse-engineered schematics (referenced as Exhibit G) will be central to the dispute.
    • Mechanical Patent (’164): For the ’164 patent, a key scope question will be whether the physical construction of the accused enclosures meets the claim limitations of a "vertical partition plate" separating a "first inner cavity" from a "second inner cavity," and whether the "adjuster of a potentiometer" is located as claimed. The image of an "Acraft 24V Dimmable LED Driver" shows an enclosure with a separate wiring compartment, which may support the plaintiff's allegations. (Compl. p. 12, Image b).

V. Key Claim Terms for Construction

’710 Patent

  • The Term: "dimmer holding current control circuit" (Claim 1, preamble).
  • Context and Importance: This term defines the invention itself. The dispute may center on whether this term should be construed functionally (any circuit that provides a holding current) or structurally (only a circuit with the specific components recited in the claim body).
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The background section describes the problem in functional terms—the need to "provide the transistor in the phase cut dimmer with a current to maintain a conducting state." (’710 Patent, col. 1:17-19).
    • Evidence for a Narrower Interpretation: The claim body recites a highly specific list of interconnected components (a field-effect transistor, a triode, multiple resistors, etc.). A defendant may argue the preamble is defined and limited by this detailed structure, which is the only one depicted in the patent's figures. (’710 Patent, Fig. 1; col. 4:27-60).

’167 Patent

  • The Term: "PWM signal conversion circuit" (Claim 4).
  • Context and Importance: This is the core functional block that allegedly enables the wide-voltage operation. Whether the accused products' signal processing architecture falls within the scope of this term will be a critical issue.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification discloses multiple distinct embodiments for this circuit, including one comprising a "PWM signal to direct current signal circuit and a direct current signal to PWM signal circuit," and another comprising an "MCU signal conversion circuit." This suggests the term is not limited to a single hardware implementation. (’167 Patent, col. 4:8-13).
    • Evidence for a Narrower Interpretation: A party could argue that despite the alternate embodiments, the term is still limited to circuits that perform the specific two-step frequency conversion process described: converting a low-frequency PWM signal (tied to the AC line frequency) into a high-frequency PWM signal (>200 Hz). (’167 Patent, col. 3:1-5).

VI. Other Allegations

  • Willful Infringement: The complaint seeks enhanced damages for willful infringement. (Compl. p. 23, ¶C). The factual basis alleged for willfulness is that "Plaintiff has provided Defendants with notice of infringement," suggesting the allegation is based on continued infringement after receiving notice. (Compl. ¶46).

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

  1. A core evidentiary question will be one of circuit equivalence: Will the plaintiff’s reverse-engineered schematics of the accused LED drivers be proven accurate, and do they demonstrate a component-level and functional correspondence to the specific circuit architectures required by the asserted electronics patents (’710, ’167, ’724, ’959)?

  2. For the ’164 patent, a key issue will be one of structural correspondence: Does the physical construction of the accused driver enclosures, particularly those with integrated junction boxes, meet the specific limitations of claim 1 regarding partitioned internal cavities and the location of a parameter adjuster?

  3. A central procedural question will be the plaintiff's ability to substantiate its "alter ego" theory. Proving that the numerous, seemingly independent defendants constitute a single, coordinated infringing enterprise will likely be critical for establishing joint liability and determining the scope of damages.