DCT

1:25-cv-23530

Voltstar Tech Inc v. Shenzhen Shi Tian LAN Mu Ju You Xian Gong Si

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-23530, S.D. Fla., 08/06/2025
  • Venue Allegations: Venue is alleged to be proper because the defendant is not a resident of the United States and has committed acts of infringement within the district.
  • Core Dispute: Plaintiff alleges that Defendant’s USB wall chargers infringe a reissue patent related to the compact physical design and dimensions of power adapters.
  • Technical Context: The technology concerns AC-to-DC power converters, commonly known as chargers, for portable electronic devices, focusing on designs that minimize physical footprint to avoid obstructing adjacent wall outlets.
  • Key Procedural History: The asserted patent, U.S. Reissue Patent No. RE48,794 E, is a reissue of U.S. Patent No. 9,024,581. During reissue, the original claims were amended to add specific dimensional limitations for the charger housing. The complaint also notes that the plaintiff has entered into licensing agreements for its patent with third parties.

Case Timeline

Date Event
2008-05-21 Earliest Priority Date for ’794 Patent (Original Filing)
2015-05-05 U.S. Patent No. 9,024,581 Issues
2018-12-04 Reissue Application for ’794 Patent Filed
2021-10-26 U.S. Reissue Patent No. RE48,794 E Issues
2025-08-06 Complaint Filed

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

U.S. Reissue Patent No. RE48,794 E - "Charger Plug With Improved Package"

The Invention Explained

  • Problem Addressed: The patent describes several problems with prior art power chargers. These include being bulky enough to block adjacent electrical outlets, protruding too far from the wall, and having a high manufacturing cost due to a complex assembly processes like insert-molding electrical blades and hand-soldering connections to internal circuit boards (PCBs) (’794 Patent, col. 1:42-61; col. 2:11-24).
  • The Patented Solution: The invention is a charger with a compact housing and a simplified assembly method. It features separate electrical blades that slidably mount into the housing and connect to the internal PCB using spring contacts rather than solder (’794 Patent, col. 3:14-27). This design, illustrated in the exploded view of FIGS. 2A-2C, aims to reduce manufacturing complexity and cost while enabling a smaller physical profile (’794 Patent, Abstract; col. 4:37-43).
  • Technical Importance: This approach sought to create a more user-friendly and less expensive charger by addressing both the physical encumbrance and the manufacturing inefficiencies common in the market at the time (’794 Patent, col. 1:42-48).

Key Claims at a Glance

  • The complaint asserts independent Claim 1 (’794 Patent, col. 13:18-14:58; Compl. ¶29).
  • The essential elements of independent Claim 1 include:
    • A charger plug for converting 120V input power to DC output power.
    • A housing containing first and second separate blade members with prong portions that extend from a front wall.
    • A DC connector on the housing for a removable power cord.
    • A specific housing size, with a longitudinal length "less than 2.0 inches" and a width of the "outer profile being less than 1.75 inches."
    • An outer profile that has "no interference with an adjacent receptacle" when a similar charger is plugged into an adjacent outlet.

III. The Accused Instrumentality

Product Identification

The accused products are a line of USB wall chargers sold by Defendant under the brand name "Tianlanmuju" on Amazon.com, identified by several ASINs (e.g., B0DPJTB4Y7, B0F7QHFSD4) (Compl. ¶21).

Functionality and Market Context

The complaint alleges the accused products are chargers that connect to an AC wall outlet to provide DC power to devices like mobile phones (Compl. ¶22). The complaint provides a table listing accused products, including a "USB Wall Charger" (ASIN B0DPJTB4Y7) sold by Defendant (Compl. ¶21). Plaintiff alleges the products feature a "reduced plug-size charger plug" that does not block adjacent outlets and allows for easy insertion and removal of a power cord while the unit is plugged in, mirroring the benefits described in the patent (Compl. ¶23-24).

IV. Analysis of Infringement Allegations

The complaint references a claim chart in Exhibit 3, which was not included with the filed complaint (Compl. ¶25, 29). The infringement theory can be summarized from the complaint's narrative allegations. Plaintiff alleges that Defendant's chargers practice each element of Claim 1 of the ’794 Patent. The core of the infringement allegation appears to rest on the physical design and dimensions of the accused chargers. The complaint states the chargers are designed to be compact, so they "do not block or interfere with the use of adjacent outlets" (Compl. ¶23) and that their "size and shape" are key features (Compl. ¶24). These allegations map directly onto the dimensional and non-interference limitations of the asserted claim (’794 Patent, col. 13:46-51).

Identified Points of Contention

  • Evidentiary Question: A central question will be evidentiary: do the accused products meet the specific dimensional limitations of Claim 1, namely a longitudinal length "less than 2.0 inches" and a width "less than 1.75 inches"? The factual accuracy of these measurements will be a primary focus.
  • Functional Question: The analysis will likely scrutinize the functional limitation of "no interference." A question for the court will be whether the "outer profile" of the accused chargers, when tested under the conditions specified in the claim (i.e., with a "like charger plug" in an adjacent outlet), results in "no interference." The meaning of "interference" itself could become a point of dispute.

V. Key Claim Terms for Construction

The Term: "a width of the housing outer profile being less than 1.75 inches" and "a longitudinal length... less than 2.0 inches"

Context and Importance

Practitioners may focus on these terms because they were added during reissue to narrow the claim scope from the original patent (Compl. ¶12, fn. 1). This amendment creates a strong presumption that the specific numeric values are critical to patentability and are not easily broadened. Infringement becomes a direct factual question of measurement.

Intrinsic Evidence for Interpretation

  • Evidence for a Broader Interpretation: A party seeking a broader reading might argue that "outer profile" is ambiguous and does not include minor, non-functional protrusions, potentially altering the measurement. The specification's general reference to reducing size could be cited to argue for the spirit of the invention over the strict letter (’794 Patent, col. 1:15-18).
  • Evidence for a Narrower Interpretation: The patent specification provides an exemplary, even smaller, preferred dimension: "lateral width... is less than 1.75 inches, and preferably approximately 1.35 inches" (’794 Patent, col. 14:4-6). This reinforces the explicit numerical ceiling. The prosecution history, showing this was a narrowing amendment, will provide strong evidence against any interpretation that reads out the precise limits.

The Term: "the outer profile having no interference with an adjacent receptacle"

Context and Importance

This is a functional limitation tied directly to the dimensional claims. The dispute will center on what constitutes "interference" and what evidence is required to prove its absence under all claimed conditions.

Intrinsic Evidence for Interpretation

  • Evidence for a Broader Interpretation: A plaintiff may argue that "interference" means only the physical prevention of plugging in a standard adjacent plug, permitting minor contact or inconvenience. The patent's background describes the problem as plugs providing "little or no interference," which might suggest a less-than-absolute standard (’794 Patent, col. 1:46-48).
  • Evidence for a Narrower Interpretation: A defendant may argue that "no interference" means a complete absence of physical contact or impediment. The claim language is highly specific, requiring this condition to be met on "all sides of the first receptacle when a like charger plug is mounted in all available orientations in any of the other receptacles" (’794 Patent, col. 13:46-51). This sets a demanding standard of proof that links the function directly to the claimed dimensions.

VI. Other Allegations

Willful Infringement

The complaint requests a finding that infringement was "willful, wanton, and deliberate" (Compl., Prayer for Relief ¶C). The basis for willfulness appears to be post-suit knowledge, as the filing of the lawsuit itself gives Defendant notice of the patent and its alleged infringement. The complaint makes a general allegation of "actual or constructive knowledge" but provides no specific facts supporting pre-suit knowledge (Compl. ¶20).

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

The resolution of this case will likely depend on the answers to two central questions:

  1. A core issue will be one of factual measurement: do the accused chargers’ physical dimensions strictly fall within the precise numerical limits of "less than 2.0 inches" in length and "less than 1.75 inches" in width? The patent's reissue history, which introduced these limitations, suggests there may be little room for deviation.

  2. A key evidentiary question will be one of functional proof: can the plaintiff demonstrate that the accused products’ "outer profile" causes "no interference with an adjacent receptacle" under all of the specific orientations and conditions recited in Claim 1? This will require a clear definition of "interference" and potentially extensive physical testing.