DCT

1:25-cv-15117

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

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-15117, N.D. Ill., 03/09/2026
  • 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 Northern District of Illinois.
  • Core Dispute: Plaintiff alleges that Defendants’ Dimmable LED Drivers, sold online in the U.S., infringe five patents related to LED power supply circuitry, dimming control, and power supply box design.
  • Technical Context: The technology at issue involves electronic drivers that control power to LED lighting systems, a critical component for enabling stable, flicker-free dimming across a wide range of input voltages and power factors.
  • Key Procedural History: The complaint does not reference any prior litigation, Inter Partes Review (IPR) proceedings, or licensing history related to the patents-in-suit.

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 ’710 Patent Issue Date
2018-04-10 ’959 Patent Issue Date
2018-05-01 ’724 Patent Issue Date
2018-07-31 ’167 Patent Issue Date
2021-02-25 ’164 Patent Priority Date
2023-08-08 ’164 Patent Issue Date
2026-03-09 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," issued May 23, 2017

The Invention Explained

  • Problem Addressed: Phase-cut dimmers, common in lighting control, require a minimum "holding current" to maintain their operational state (Compl. ¶5). Conventional methods for providing this current are often inefficient, resulting in high power consumption, significant heat generation, and potential for audible noise and vibration in the dimmer circuit (’710 Patent, col. 1:13-35).
  • The Patented Solution: The patent describes a control circuit designed to provide a stable holding current with high efficiency. The solution uses a combination of a field-effect transistor and a triode to create a controlled current loop that limits power consumption and heat. The circuit is also designed to cut off automatically when the input voltage is in a range where the holding current is not needed, further improving efficiency (’710 Patent, abstract; ’710 Patent, col. 4:6-23).
  • Technical Importance: This approach allows for the creation of more reliable and energy-efficient dimmable LED drivers that are compatible with existing phase-cut dimmer infrastructure (’710 Patent, col. 1:46-56).

Key Claims at a Glance

The complaint asserts infringement of claim 1, which is an independent claim (Compl. ¶48). The core elements of claim 1 include:

  • A dimmer holding current control circuit for phase cut dimming power supply, comprising a phase cut dimming power supply circuit, an LED lamp, and a dimmer holding current control circuit.
  • The dimmer holding current control circuit is composed of a rectifier diode I, a rectifier diode II, a field-effect transistor, a triode, multiple current-limiting and sampling resistances, a diode, a capacitance, and a resistance.
  • Specific connectivity between these components, including the anodes of the rectifier diodes connected to the L and N terminals of the main supply.
  • The cathodes of the rectifier diodes are connected to each other and to one end of a current-limiting resistance.
  • The other end of the current-limiting resistance is connected to the drain of the field-effect transistor.
  • The emitter of the triode is connected to the circuit common ground.

The complaint alleges infringement of "one or more claims, including claim 1," thereby reserving the right to assert other claims (Compl. ¶48).

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 often designed for narrow input voltage ranges specific to certain geographic regions (e.g., 90-130V for North America or 170-265V for Europe). This limits their applicability in a global market and requires manufacturers to maintain multiple product versions (’167 Patent, col. 1:26-34).
  • The Patented Solution: The invention discloses a circuit that enables phase-cut dimming over a wide input voltage range (e.g., 90-305V). It achieves this by converting the chopped alternating current signal from the dimmer into a low-frequency Pulse Width Modulation (PWM) signal. The duty cycle of this PWM signal, which dictates the brightness level, is determined by the dimmer's setting and is independent of the AC input voltage's magnitude. This PWM signal then controls the final output to the LED lamp, ensuring consistent dimming performance regardless of the input voltage (’167 Patent, abstract; ’167 Patent, col. 2:54-68).
  • Technical Importance: This technology allows a single LED driver product to be compatible with electrical grids worldwide, simplifying manufacturing and inventory for global distribution (’167 Patent, col. 1:39-44).

Key Claims at a Glance

The complaint asserts infringement of claim 4, which is an independent claim (Compl. ¶51). The core elements of claim 4 include:

  • A phase-cut dimming circuit comprising: a first diode, a second diode, multiple resistors, a transistor, a photoelectric coupler, and a PWM signal conversion circuit.
  • Positive terminals of the first and second diodes are respectively connected to the phase (L) and neutral (N) lines of a power supply.
  • Negative terminals of the diodes are connected to a first resistor.
  • The collector of the transistor is connected to the light-emitting tube of the photoelectric coupler.
  • An output of the photoelectric coupler is connected to an input of the PWM signal conversion circuit.
  • An output of the PWM signal conversion circuit is connected to a gate of a field effect transistor, which in turn controls the LED lamp.

The complaint alleges infringement of "one or more claims, including claim 4," reserving the right to assert others (Compl. ¶51).

Multi-Patent Capsules

  • 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 phase-cut dimming power supplies (’724 Patent, col. 1:25-52). The solution is a system architecture that integrates an active power factor correction (PFC) circuit with a power conversion circuit and signal conversion logic, enabling the power supply to maintain high efficiency and a high power factor (≥0.95) while being compatible with phase-cut dimmers (’724 Patent, abstract; ’724 Patent, col. 2:25-40).
    • Asserted Claims: Independent claim 1 is asserted (Compl. ¶54).
    • Accused Features: The complaint alleges that the overall circuitry of the accused Dimmable LED Drivers, which allegedly includes PFC and signal conversion functionalities, infringes this patent (Compl. ¶55; Compl. ¶67; Compl. ¶79; Compl. ¶91).

  • 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, aims to solve the problem of narrow input voltage ranges in dimmable power supplies (’959 Patent, col. 1:21-42). The proposed solution uses a combination of an anti-interference circuit, an active power factor correction circuit, and a wide-input-voltage dimming control circuit that generates a PWM signal to control an external field effect transistor, thereby enabling stable dimming across a wide voltage input while maintaining compatibility with various dimmers (’959 Patent, abstract).
    • Asserted Claims: Independent claim 4 is asserted (Compl. ¶57).
    • Accused Features: The complaint accuses the comprehensive circuitry within the Dimmable LED Drivers, which allegedly enables wide voltage input and dimming control, of infringement (Compl. ¶58; Compl. ¶70; Compl. ¶82; Compl. ¶94).

  • U.S. Patent No. 11,723,164, “Convenient Power Supply Box for Quick Parameter Adjustment,” issued August 8, 2023

    • Technology Synopsis: This patent addresses a mechanical design problem: conventional power supply boxes lack convenient wire storage and make it difficult to access internal components for parameter adjustment (’164 Patent, col. 1:28-34). The invention is a power supply box with a body containing separate internal cavities for the main circuitry (including an adjustable potentiometer) and for wire storage. Partition plates and open slots facilitate organized wire routing between the cavities, and a multi-part cover allows selective access (’164 Patent, abstract; ’164 Patent, col. 2:43-52).
    • Asserted Claims: Independent claim 1 is asserted (Compl. ¶96).
    • Accused Features: The complaint accuses the physical housing of certain accused products, particularly those with junction boxes, of infringing the patented design (Compl. ¶97). The complaint includes an image of an accused waterproof driver with an integrated junction box, which appears to be the target of this allegation (Compl. p. 10).

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are various models of "Dimmable LED Drivers" (Compl. ¶34; Compl. ¶38). The complaint alleges these are manufactured by Defendant DEMI and sold through numerous online storefronts on Amazon.com, which are claimed to be "alter egos of each other" (Compl. ¶¶12, 34).

Functionality and Market Context

The accused products are power supplies designed to convert AC input voltage into a controlled DC output suitable for powering LED lights (Compl. ¶5). They are advertised with features such as compatibility with multiple dimming protocols (e.g., TRIAC/Phase-cut, 0-10V) and are sold to consumers in the United States for commercial and residential lighting projects (Compl. ¶¶3, 34). The complaint alleges that Plaintiff's engineers reverse-engineered twelve purchased units and created circuit diagrams, finding them to have "the same or substantially equivalent circuitry" that infringes the asserted patents (Compl. ¶42). The complaint provides an image of an accused "Dimmable LED Driver 24V 120W" sold by one of the defendant storefronts, showing its external housing and labeling (Compl. p. 11). Another image depicts an "Acraft 24V Dimmable LED Driver 96W" sold by a different defendant, illustrating a similar product form factor with a junction box (Compl. p. 12).

IV. Analysis of Infringement Allegations

The complaint alleges that infringement was confirmed through examination, testing, and reverse-engineering of the accused products (Compl. ¶¶42-44). It states that detailed claim charts are provided in Exhibits H-L, which are incorporated by reference but were not attached to the publicly filed complaint (Compl. ¶44). The analysis below is based on the asserted claims and the complaint's narrative allegations.

’710 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A dimmer holding current control circuit...is composed of a rectifier diode I, a rectifier diode II, a field-effect transistor, a triode... The complaint alleges that reverse-engineered circuit diagrams of the accused drivers show the presence of these discrete electronic components arranged to form the claimed control circuit. ¶49; ¶61; ¶73; ¶85 col. 4:39-41
the anodes of the rectifier diode I and the rectifier diode II are respectively connected to L terminal and N terminal of main supply input... Based on testing and circuit analysis, the complaint alleges the accused drivers' input stages contain rectifier diodes connected to the main AC supply lines. ¶49; ¶61; ¶73; ¶85 col. 4:35-39
the other end of the current-limiting resistance I is connected to the drain electrode of the field-effect transistor... The complaint asserts that the reverse-engineered schematics confirm the specific electrical connections between the current-limiting resistor and the field-effect transistor as required by the claim. ¶49; ¶61; ¶73; ¶85 col. 4:46-49
the other end of the sampling resistance II...and the emitter of the triode are connected to the circuit common ground. The complaint alleges that the circuit diagrams of the accused products show that the sampling resistor and the triode's emitter share a common ground connection, satisfying this limitation. ¶49; ¶61; ¶73; ¶85 col. 4:58-61

’167 Patent Infringement Allegations

Claim Element (from Independent Claim 4) Alleged Infringing Functionality Complaint Citation Patent Citation
A phase-cut dimming circuit comprising...a transistor, a photoelectric coupler, and a PWM signal conversion circuit; The complaint alleges, based on reverse engineering, that the accused drivers contain a circuit architecture with these functional components to manage dimming across a wide voltage range. ¶52; ¶64; ¶76; ¶88 col. 8:36-40
wherein a positive terminal of the first diode, and a positive terminal of the second diode are respectively connected to a phase line L and a zero line N of a power supply; Analysis of the accused products' input circuitry allegedly confirms the presence of diodes connected to the AC power lines as claimed. ¶52; ¶64; ¶76; ¶88 col. 8:41-45
an output of the photoelectric coupler is connected to an input of the PWM signal conversion circuit; The complaint alleges that the reverse-engineered schematics show a signal path from an opto-isolator (photoelectric coupler) to a circuit block that performs PWM signal conversion. ¶52; ¶64; ¶76; ¶88 col. 8:60-62
and an output of the PWM signal conversion circuit is connected to a gate of the field effect transistor. The complaint asserts the accused drivers' circuitry uses the output of the PWM conversion block to control the switching of a field effect transistor, which in turn modulates power to the LEDs. ¶52; ¶64; ¶76; ¶88 col. 8:62-65
  • Identified Points of Contention:
    • Evidentiary Questions: The central issue will be factual. The complaint's infringement theory rests entirely on reverse-engineering analysis detailed in exhibits that are not part of the public record (Compl. ¶¶42, 44). The dispute will focus on whether this analysis accurately represents the circuitry of the accused products and whether that circuitry, in operation, meets every limitation of the asserted claims.
    • Scope Questions: The case may raise questions regarding the scope of functional language in the claims. For instance, a point of contention could be whether the circuitry in the accused products constitutes a "PWM signal conversion circuit" as that term is understood in the context of the ’167 Patent specification.

V. Key Claim Terms for Construction

  • The Term: "PWM signal conversion circuit" (from claim 4 of the ’167 Patent)

  • Context and Importance: This term describes a core functional block of the invention in the ’167 Patent. The infringement analysis for this patent will depend on whether the accused drivers' circuitry performs the function of converting a phase-cut signal into a PWM signal in a manner that falls within the claim's scope. Practitioners may focus on this term because it is defined by its function rather than a specific list of components.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The claim language itself is broad, requiring a "PWM signal conversion circuit" without specifying its internal components (’167 Patent, col. 8:36-40). This may support an argument that any circuit performing the specified conversion function infringes.
    • Evidence for a Narrower Interpretation: The specification describes specific embodiments of this circuit, including one that comprises a "PWM signal to direct current signal circuit" followed by a "direct current signal to PWM signal circuit" (’167 Patent, col. 4:8-10). This could support a narrower construction limited to the disclosed embodiments and their structural equivalents.

  • The Term: "dimmer holding current control circuit" (from claim 1 of the ’710 Patent)

  • Context and Importance: This term defines the invention of the ’710 Patent. The dispute will likely center on whether the combination of components in the accused products, as identified through reverse engineering, is arranged to perform the specific function of providing a stable holding current in the manner claimed.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The claim preamble introduces the circuit by its function, which could support a construction focused on the overall purpose rather than the precise implementation (’710 Patent, col. 4:26-28).
    • Evidence for a Narrower Interpretation: Claim 1 recites a specific list of components (field-effect transistor, triode, specific resistors, etc.) and their interconnections (’710 Patent, col. 4:39-61). This detailed structural recitation may support a narrower construction that requires the presence of all listed components or their clear equivalents arranged in the claimed configuration.

VI. Other Allegations

  • Indirect Infringement: The complaint does not contain specific counts for indirect infringement (inducement or contributory infringement). The infringement counts are pleaded under 35 U.S.C. § 271 generally, which is most directly read as alleging direct infringement (Compl. ¶48; Compl. ¶51).
  • Willful Infringement: The complaint alleges that "Plaintiff has provided Defendants with notice of infringement pursuant to 35 U.S.C. § 287" (Compl. ¶46). The prayer for relief explicitly requests "enhanced damages for willful infringement pursuant to 35 U.S.C. § 284" (Compl. p. 23, ¶C). These allegations form the basis for a claim of willful infringement, potentially based on alleged pre-suit and ongoing post-suit knowledge of the patents.

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

  • A central issue will be one of evidentiary proof: The complaint's allegations are heavily reliant on reverse-engineering analysis contained in exhibits that are not publicly available. A key question for the court will be whether this evidence, once produced, can convincingly demonstrate that the circuitry within the accused products, sold by numerous distinct storefronts, practices the specific limitations of the asserted claims.
  • A second core issue will be one of claim construction and functional equivalence: The case will likely turn on the court's interpretation of functional terms such as "PWM signal conversion circuit" (’167 Patent). A key question will be whether the accused circuits perform the claimed functions in substantially the same way to achieve substantially the same result, or if there are fundamental mismatches in technical operation that place them outside the scope of the claims.
  • A significant procedural question will be the viability of joinder: The plaintiff has sued a large number of defendants, alleging they are a network of "alter egos" for a single manufacturer (Compl. ¶34). A threshold question will be whether the plaintiff can substantiate this "concerted action" theory to keep the numerous defendants joined in a single case and establish liability across the alleged enterprise.
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