DCT
1:25-cv-25654
Magic Christmas HK Co Ltd v. Let Lit
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Magic Christmas (HK) Co. Ltd. (China)
- Defendant: Let Lit (China)
- Plaintiff’s Counsel: Feldenkrais Law, P.A.
- Case Identification: 1:25-cv-25654, S.D. Fla., 12/03/2025
- Venue Allegations: Plaintiff alleges venue is proper because Defendant is an alien entity. Further allegations state Defendant targets and serves consumers in Florida through an Amazon e-commerce store, accepts payment in U.S. dollars, and offers shipping to Florida addresses.
- Core Dispute: Plaintiff, as licensee, alleges that Defendant’s LED lighting products sold on Amazon.com infringe two patents related to systems for simultaneously providing power and control signals to LED light strings over a single power line.
- Technical Context: The technology at issue involves methods for simplifying the wiring and improving the stability of digitally controlled lighting systems, such as decorative LED strings, by transmitting control data on the same line that supplies electrical power.
- Key Procedural History: The complaint notes that a prior, similar lawsuit filed by the Plaintiff against multiple defendants was dismissed without prejudice for failure to comply with procedural rules regarding joinder. The current action has been refiled against a single defendant to remedy that issue. The complaint also references two prior infringement actions filed by the licensor of the patents-in-suit, one of which was voluntarily dismissed and the other stayed.
Case Timeline
| Date | Event |
|---|---|
| 2009-11-06 | U.S. Patent No. 8,344,659 Priority Date |
| 2013-01-01 | U.S. Patent No. 8,344,659 Issued |
| 2019-03-14 | U.S. Patent No. 10,863,608 Priority Date |
| 2020-12-08 | U.S. Patent No. 10,863,608 Issued |
| 2025-11-17 | Prior related action (1:25-cv-23748) dismissed without prejudice |
| 2025-12-03 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 10,863,608 B2 - "Light-Emitting Diode Driving System for Transmitting Signal Based on Power Line"
The Invention Explained
- Problem Addressed: The patent’s background describes prior art LED driving systems as having "weak" signal generation circuits, which can cause the LED light string to be in a "non-operating state" and result in an unstable display effect (’608 Patent, col. 1:36-43).
- The Patented Solution: The invention proposes a system that uses a control unit to alternate between a "main power supply" and a "secondary power supply" to create a composite "light emission driving signal" on a single power line (’608 Patent, col. 2:1-11). By ensuring the switch unit is "always in a turned-on state," the system provides stable and uninterrupted power to the LED string, which avoids the instability of prior art systems (’608 Patent, col. 2:42-49). The complaint includes a reproduction of the patent's Figure 1 to illustrate this system architecture (Compl. p. 4).
- Technical Importance: This approach aims to provide stable light emission while transmitting a control signal over a single power line, thereby eliminating the need for an extra control signal line (Compl. ¶10).
Key Claims at a Glance
- The complaint asserts infringement of at least Claim 1 of the ’608 Patent (Compl. ¶26).
- Independent Claim 1 recites a system comprising:
- at least a switch unit, a control unit, a main power supply, and a secondary power supply.
- the switch unit having a main input end (connected to the main power supply), a secondary input end (connected to the secondary power supply), an output end (connected to an LED string), and a controlled end (connected to the control unit).
- the switch unit is always turned on when the control unit is in an operating state.
- the switch unit imports current from the main power supply upon receiving a high level signal from the control unit.
- the switch unit imports current from the secondary power supply upon receiving a low level signal from the control unit.
- the switch unit outputs a light emission driving signal composed of the main and secondary current power supplies to maintain stable light emission.
U.S. Patent No. 8,344,659 B2 - "System and Method for Lighting Power and Control System"
The Invention Explained
- Problem Addressed: The patent background highlights the complexity and expense of large-scale, multi-color LED display systems, which require providing "carefully metered and individually controlled electric power" to potentially millions of individual LEDs (’659 Patent, col. 1:46-60).
- The Patented Solution: The invention is a "single-wire multiple-LED power and control system" (’659 Patent, Abstract). A head-end "line driver circuit" drives an electrical current down a single output line to a series of connected control units. The line driver circuit "modulates digital illumination control data onto said electrical current." Each control unit along the series arrangement draws its operating power directly from this current and simultaneously demodulates the control data to operate one or more associated LEDs (’659 Patent, col. 41:41-col. 42:2). The complaint includes a block diagram from the patent illustrating the LED Line Driver circuit (Compl. p. 5).
- Technical Importance: This architecture greatly simplifies the design, wiring, and construction of systems with numerous individually controllable lighting elements by providing both power and data over a single wire (’659 Patent, col. 5:28-32).
Key Claims at a Glance
- The complaint asserts infringement of at least Claim 1 of the ’659 Patent (Compl. ¶26).
- Independent Claim 1 recites a system comprising:
- a power supply for supplying electrical power.
- a line driver circuit that receives power from the power supply and digital illumination control data from a controller.
- the line driver circuit drives an output line with an electrical current and modulates the digital data onto that current.
- more than one controlled unit coupled in a series arrangement to the output line.
- each controlled unit draws operating power from the electrical current on the output line.
- each controlled unit demodulates the digital data from the output line.
- each controlled unit uses the digital data to control at least one illumination device.
III. The Accused Instrumentality
Product Identification
- The complaint identifies the accused products as "goods" manufactured, imported, and sold by Defendant LET LIT through an e-commerce store on Amazon.com (Compl. ¶¶1, 3). While not explicitly named, the context suggests they are digitally controlled LED lighting systems, such as decorative light strings (Compl. ¶¶10, p. 4).
Functionality and Market Context
- The complaint alleges that the accused products incorporate the patented technologies, providing an LED driving system that transmits a lamp control signal over a single power line (Compl. ¶10). The products are allegedly sold to consumers throughout the United States, including Florida, via the Amazon marketplace (Compl. ¶¶12-13, 19).
IV. Analysis of Infringement Allegations
The complaint references a claim chart in Exhibit 2, which was not available for this analysis (Compl. ¶26). The following tables summarize the infringement allegations based on the narrative descriptions provided in the body of the complaint.
’608 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a light-emitting diode driving system for transmitting a signal based on a power line...comprising: at least a switch unit, a control unit, a main power supply, and a secondary power supply | The accused products are alleged to be an LED driving system for transmitting a lamp control signal based on a single power line. | ¶10 | col. 3:51-54 |
| the switch unit outputs...a light emission driving signal composed of the main and secondary current power supplies | The accused system is alleged to configure a switch unit to output a light emission driving signal composed of main and secondary power supplies. | ¶10 | col. 4:11-14 |
| so as to maintain stable light emission | The alleged purpose of the accused system's design is to maintain stable light emission. | ¶10 | col. 4:14-16 |
| no extra lamp control signal line is necessary aside from the already existing power line(s) | The accused system is alleged to operate based on a single power line without a separate control signal line. | ¶10 | col. 1:52-54 |
’659 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a digitally controlled illumination system, said...system comprising: a power supply for supplying electrical power; | The accused products are alleged to be a digitally controlled illumination system with a power supply. | p. 4 | col. 41:41-45 |
| a line driver circuit, said line driver circuit receiving power from said power supply, said line driver circuit receiving digital illumination control data from a controller... | The accused system is alleged to contain a line driver circuit that receives power and digital illumination control data. | p. 4 | col. 41:46-49 |
| said line driver...modulating said digital illumination control data onto said electrical current | The line driver circuit in the accused system allegedly modulates digital control data onto the electrical current. | p. 4 | col. 41:51-54 |
| more than one controlled unit coupled in a series arrangement to said output line | The accused system allegedly connects more than one control unit in series on the output line. | p. 4 | col. 42:55-56 |
| each said controlled unit drawing operating power from said electrical current on said output line | Each control unit in the accused system allegedly takes its operating power from the electric current on the output line. | p. 4 | col. 42:57-59 |
| each said controlled unit demodulating said digital illumination control data from said output line | Each control unit in the accused system allegedly demodulates the digital data carried by the current line. | p. 4 | col. 42:60-61 |
- Identified Points of Contention:
- Scope Questions: A central question for the ’608 Patent may be whether the accused product's power source constitutes distinct "main" and "secondary" power supplies as claimed, or if it utilizes a single power source that is modulated in a way that falls outside the claim's scope.
- Technical Questions: For the ’659 Patent, a key factual dispute may concern whether the controller in the accused product actually performs the dual functions of both drawing its own operating power and demodulating control data from the same modulated current, as required by the claim.
V. Key Claim Terms for Construction
The Term: "the switch unit is always turned on when the control unit is in an operating state" (’608 Patent, Claim 1).
Context and Importance: This phrase is central to the ’608 Patent’s asserted novelty of providing "stable light emission." The dispute will likely focus on whether the accused product’s switching mechanism can be characterized as "always turned on." Practitioners may focus on this term because if the accused device has any discernible "off" state during operation, it may not infringe.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification states that because the main and secondary switches are turned on alternately, "the switch unit is always in a turned-on state, and the LED light string is also always in a normal operating state" (’608 Patent, col. 2:42-45). This supports an interpretation where continuous power delivery, regardless of the source, constitutes being "always on."
- Evidence for a Narrower Interpretation: The claim requires distinct high and low level signals to control the switches. A defendant may argue that the transition time between these states, or any other moment of non-power delivery, constitutes an "off" state, however brief, meaning the switch is not "always turned on." The alternate operation could be argued to imply a non-overlapping, break-before-make switching sequence.
The Term: "modulating said digital illumination control data onto said electrical current" (’659 Patent, Claim 1).
Context and Importance: This limitation defines how control signals are transmitted without a separate wire. The case may turn on whether the specific method of signal transmission used by the accused product is a form of "modulating...onto said electrical current."
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim language itself is broad. The specification discloses modulating data using "small up and down spikes from the nominal constant current value," which may support construing the term to cover any method of embedding data by intentionally varying the line current (’659 Patent, col. 7:60-63).
- Evidence for a Narrower Interpretation: The patent details specific embodiments for achieving this modulation, such as creating positive and negative current spikes to represent binary data (Fig. 3) and using complex ramp circuits to control current changes (Figs. 5A-6C). A defendant could argue the term should be limited to these specific current-based modulation techniques, and not other signaling methods that might also affect current as a byproduct (e.g., voltage modulation).
VI. Other Allegations
- Indirect Infringement: The complaint makes a conclusory allegation of indirect infringement (Compl. ¶46), but it does not plead specific facts to support claims of either induced infringement (e.g., knowledge and intent demonstrated through user manuals) or contributory infringement. The core allegations support a theory of direct infringement.
- Willful Infringement: Willfulness is alleged based on the assertion that Defendant's infringement is "deliberate and wilful" (Compl. ¶3) and that Defendant "knew or should have known" of Plaintiff's patent rights (Compl. ¶32). The complaint does not allege specific facts indicating pre-suit knowledge, such as receipt of a notice letter.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of technical implementation: Do the accused commodity LED lighting products employ the specific and distinct two-source power architecture ("main" and "secondary" power supplies) required by Claim 1 of the ’608 Patent, or do they achieve a similar result using a different, single-source power modulation scheme?
- A key evidentiary question will be one of functional integration: What technical evidence exists to demonstrate that the integrated circuits in the accused products perform the dual functions of both drawing their own operating power and demodulating control data from the same modulated current on a single line, as recited by Claim 1 of the ’659 Patent?
- A third question will be one of definitional scope: Can the phrase "always turned on" in the ’608 Patent be construed to read on a system that alternates between two power sources, potentially creating brief transitional states, and can "modulating...onto said electrical current" in the ’659 Patent encompass the specific signaling protocol used in the accused products?