DCT
1:25-cv-01791
Voltstar Tech Inc v. Amazon.com Inc
Key Events
Amended Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Voltstar Technologies, Inc. (Illinois)
- Defendant: Amazon.com, Inc. and Amazon.com Services LLC (Delaware)
- Plaintiff’s Counsel: Sriplaw PLLC
- Case Identification: 1:25-cv-01791, S.D.N.Y., 10/15/2025
- Venue Allegations: Plaintiff alleges venue is proper in the Southern District of New York because Defendants have committed acts of infringement in the district and maintain a regular and established place of business there.
- Core Dispute: Plaintiff alleges that Defendant’s USB power adapters and wireless chargers infringe four patents related to the physical design of charger plugs and energy-saving circuitry that reduces "phantom load."
- Technical Context: The technology at issue concerns the design and functionality of common consumer power adapters, focusing on physical compactness to avoid blocking adjacent outlets and internal circuitry to automatically cut power when a device is fully charged.
- Key Procedural History: Two of the patents-in-suit, RE48,794 and RE50,625, are reissues of U.S. Patent No. 9,024,581, a process which typically involves amending or narrowing claim scope to address potential validity issues. The complaint notes that the ’794 Patent’s reissue amended claim language to further limit the claimed physical dimensions of the charger. The other two patents, U.S. Patent Nos. 7,910,833 and 7,960,648, belong to a separate family and have undergone prior inter partes reexamination and inter partes review proceedings, which resulted in the cancellation or amendment of certain claims not asserted in this complaint. This history may narrow the scope of the asserted claims and frame future claim construction arguments.
Case Timeline
| Date | Event |
|---|---|
| 2008-05-21 | Priority Date for ’794 and ’625 Patents |
| 2008-05-27 | Priority Date for ’833 and ’648 Patents |
| 2011-03-22 | ’833 Patent Issued |
| 2011-06-14 | ’648 Patent Issued |
| 2015-05-05 | Original U.S. Patent No. 9,024,581 Issued |
| 2021-10-26 | ’794 Patent (Reissue) Issued |
| 2022-10-07 | ’625 Patent (Reissue) Issued |
| 2025-10-15 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. RE48,794 E - "Charger Plug With Improved Package," issued October 26, 2021
The Invention Explained
- Problem Addressed: The patent’s background section describes issues with prior art charger plugs, noting they are often bulky, interfering with adjacent wall outlets, and have an increased length that makes them susceptible to being struck or dislodged (RE48,794 Patent, col. 1:41-61). The patent also identifies the manufacturing process of insert-molding and soldering electrical blades as costly and time-consuming (RE48,794 Patent, col. 2:6-30).
- The Patented Solution: The invention is a charger plug with a reduced physical profile and a simplified construction that avoids insert molding and soldering (RE48,794 Patent, Abstract). It achieves this through a housing that slidably receives the electrical blades and uses internal, solder-less spring contacts to establish an electrical connection between the blades and the printed circuit board (RE48,794 Patent, col. 3:13-24).
- Technical Importance: The technology addresses the widespread consumer need for more compact and convenient power adapters for the growing market of portable electronic devices (RE48,794 Patent, col. 1:21-25).
Key Claims at a Glance
- The complaint asserts independent Claim 1 (Compl. ¶54).
- Claim 1 recites the essential elements of:
- A charger plug housing with a specific face area, outer profile, and rear end.
- Specific sizing limitations: a longitudinal length less than 2.0 inches and a width less than 1.75 inches.
- A functional limitation wherein the outer profile causes "no interference with an adjacent receptacle."
- A DC connector and power cord plug end that can be conveniently removed while the charger is plugged in.
U.S. Patent No. 7,910,833 - "Energy-Saving Power Adapter/Charger," issued March 22, 2011
The Invention Explained
- Problem Addressed: The patent’s background section addresses the problem of "phantom load," which is the residual power consumed by adapters when they are left plugged into an outlet but are not connected to a device or the device is fully charged (’833 Patent, col. 2:1-8). This continuous power draw is described as wasteful and environmentally impactful (’833 Patent, col. 2:9-13).
- The Patented Solution: The invention is a power adapter with circuitry that automatically determines an "off" state and cuts power draw from the source when the attached electronic device is not drawing power (’833 Patent, Abstract). A key aspect of the solution is a "load sensing portion" that can detect this low-power state by sensing characteristics of electrical pulses within the circuitry, rather than simply measuring voltage or current magnitude (’833 Patent, col. 9:26-38).
- Technical Importance: This technology provides an automatic solution to reduce energy waste from the millions of power adapters constantly plugged into outlets worldwide (’833 Patent, col. 2:4-13).
Key Claims at a Glance
- The complaint asserts independent Claims 24 and 33 (Compl. ¶66).
- Claim 24, as amended during reexamination, recites the essential elements of:
- A power device with a first portion for receiving input power and a second portion for delivering output power.
- Power circuitry for converting power and for "determining an 'off' state."
- Switching circuitry operable to activate the power circuitry to an "on" state.
- A "load sensing portion" that senses one or more pulses to determine the power being drawn, specifically by "measuring the frequency of the pulses."
U.S. Patent No. RE50,625 E - "Charger Plug With Improved Package," issued October 7, 2022
- Technology Synopsis: The ’625 Patent is a second reissue of the same original patent as the ’794 Patent. The complaint states that this patent adds claims directed to specific internal structural elements, such as a spring-based, solder-less connection between the charger's blade members and its internal circuit board (Compl. ¶20).
- Asserted Claims: Claims 20, 21, 23, 26, 30, 36, and 28 are asserted (Compl. ¶59).
- Accused Features: The complaint alleges that the internal construction of the Kindle 5W and 9W chargers, specifically their use of a printed circuit board and solder-less spring contacts to connect to the blade members, infringes the ’625 Patent (Compl. ¶60-61).
U.S. Patent No. 7,960,648 - "Energy-Saving Cable Assemblies," issued June 14, 2011
- Technology Synopsis: The ’648 Patent is a continuation of the ’833 Patent, also directed at reducing "phantom" load in chargers. The invention relates to a charger that automatically shuts off when an attached mobile device is fully charged or unplugged, thereby reducing power consumption (Compl. ¶28).
- Asserted Claims: Claims 31, 32, and 39 are asserted (Compl. ¶71).
- Accused Features: The complaint alleges that the Amazon Wireless Charger utilizes internal monitoring and switch circuitry that infringes the ’648 patent (Compl. ¶49, ¶51).
III. The Accused Instrumentality
Product Identification
- The accused products are the "Amazon 5W USB Official OEM Charger," the "Amazon 9W USB Official OEM Charger," and the "Amazon Basics Wireless Charging Stand" (Compl. ¶29, 36, 43). The complaint includes an image of the Kindle 5W Charger as an example of the accused USB chargers (Compl. p. 9).
Functionality and Market Context
- The Kindle 5W and 9W Chargers are described as AC-to-DC power adapters for Amazon’s Fire Tablets and Kindle eReaders (Compl. ¶29, 36). The complaint alleges these chargers employ a "reduced plug-size" design such that they do not block or interfere with the use of adjacent outlets when plugged into a wall socket (Compl. ¶31, 38).
- The Amazon Basics Wireless Charger is identified as a Qi-compliant wireless charging stand that uses electromagnetic induction to charge devices like mobile phones (Compl. ¶44-47). To function, the complaint alleges the device must contain internal monitoring and switching circuitry to detect when a device requires charging or is fully charged, and to control the flow of current accordingly (Compl. ¶48). An image of the Amazon Wireless Charger shows a stand-style device for holding a phone during charging (Compl. p. 12).
IV. Analysis of Infringement Allegations
The complaint references claim chart exhibits that are not provided; the following summaries are based on the narrative allegations in the complaint.
RE48,794 E Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a charger plug housing forming... a charger plug face area... an outer profile... and a rear end | The Kindle 5W and 9W Chargers are housed in a plastic enclosure that connects to a wall outlet. | ¶29-30 | col. 13:36-44 |
| being sized so that the charger plug housing comprises a longitudinal length... less than 2.0 inches, a width of the housing outer profile being less than 1.75 inches | The Kindle 5W Charger has an approximate length of 1.568 inches and width of 1.494 inches. The Kindle 9W Charger has an approximate length of 1.916 inches and width of 1.494 inches. | ¶35, 42 | col. 13:46-51 |
| the outer profile having no interference with an adjacent receptacle of the power source | Upon plugging the Kindle Chargers into a source of AC power such as a wall outlet, they do not block or interfere with the use of adjacent outlets. | ¶31, 38 | col. 13:52-59 |
| a power cord for the device to be charged may be easily inserted into and removed from the... Charger while the charger is plugged into the source of AC power | The size and shape of the Kindle Chargers allow a power cord to be easily inserted and removed while the charger is plugged in. | ¶32, 39 | col. 13:62-67 |
7,910,833 B2 Infringement Allegations
| Claim Element (from Independent Claim 24, as amended) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| power circuitry for... determining an “off” state of the power device | The Amazon Wireless Charger utilizes internal monitoring circuitry to detect when a mobile electronic device is fully charged, which determines an "off" state for the device. | ¶48-49 | col. 13:39-44 |
| switching circuitry operable to electrically activate the power circuitry to the “on” state | The Amazon Wireless Charger comprises one or more internal switches (mechanical or electrical) that control the flow of current. | ¶48-49 | col. 13:45-47 |
| a load sensing portion operable to sense one or more pulses and determine the power or load being drawn... by measuring the frequency of the pulses | The complaint alleges the internal circuitry of the wireless charger requires a "novel load sensing portion, which senses the frequency of pulses rather than sensing the magnitude of a voltage and/or current, to determine the load being drawn." | ¶48 | col. 13:48-53 |
Identified Points of Contention
- Scope Questions: For the ’794 Patent, a central question may be the scope of the term "no interference." Does this term require a complete lack of physical overlap with the space of an adjacent outlet, or does it set a functional standard where an adjacent outlet remains usable?
- Technical Questions: For the ’833 Patent, the dispute may focus on the actual method of operation of the Amazon Wireless Charger's circuitry. A key evidentiary question is whether the accused device's "load sensing portion" actually functions by "measuring the frequency of the pulses," as required by the amended claim, or if it uses a more conventional method such as sensing voltage or current levels. The complaint alleges the former but provides no direct evidence of the internal technical operation (Compl. ¶48).
V. Key Claim Terms for Construction
Term: "no interference with an adjacent receptacle" (from Claim 1 of the ’794 Patent)
- Context and Importance: The definition of this term is central to the infringement analysis for the ’794 Patent. Whether the accused chargers meet this limitation depends on whether "interference" is interpreted as a strict geometric constraint or a functional one.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader (Functional) Interpretation: The patent’s background section frames the problem functionally, stating that prior art plugs impede the "use of an adjacent receptacle" (RE48,794 Patent, col. 1:47-48). This could support an interpretation where infringement occurs only if the accused charger actually prevents a standard plug from being used in the adjacent socket.
- Evidence for a Narrower (Geometric) Interpretation: The claim itself recites specific dimensional limitations (length < 2.0", width < 1.75"). A defendant may argue that these dimensions represent the patentee's own definition of what constitutes "no interference," suggesting that any device meeting those dimensions is presumed not to interfere, regardless of the specific geometry of a given wall outlet.
Term: "a load sensing portion operable to sense one or more pulses and determine the power or load... by measuring the frequency of the pulses" (from Claim 24 of the ’833 Patent)
- Context and Importance: This term, added during reexamination, appears to be the core technical distinction of the claimed invention over the prior art. Infringement of the ’833 Patent will likely depend entirely on whether the accused wireless charger employs this specific load-sensing methodology. Practitioners may focus on this term because its narrow, technical nature makes it a clear potential point of non-infringement if the accused device uses a different sensing method.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The detailed description discusses sensing the "pulse width" and recognizing "how slow or fast the pulse is repeated to determine the load" (’833 Patent, col. 9:32-35). A plaintiff might argue this supports a construction that covers various pulse-timing-based measurements, not just a strict frequency calculation.
- Evidence for a Narrower Interpretation: The claim was amended during reexamination to add the specific phrase "by measuring the frequency of the pulses" (US 7,910,833 C1 Certificate, col. 2:18-20). Prosecution history estoppel may limit the patentee to a narrow definition of this term, as it was added to secure patentability over prior art.
VI. Other Allegations
- Willful Infringement: The complaint’s prayer for relief requests a finding of willful infringement and enhanced damages (Compl., p. 17, ¶C). However, the factual allegations within the body of the complaint do not specify a basis for this claim, such as alleged pre-suit knowledge of the patents or egregious conduct by the defendant.
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of definitional scope: How will the court construe the functional limitation "no interference" in the ’794 Patent? Will it be tied strictly to the dimensional limits recited in the claim, or will it require a functional analysis of whether the accused chargers physically obstruct the use of adjacent standard outlets?
- A key evidentiary question will be one of technical operation: What evidence will demonstrate that the Amazon Wireless Charger’s internal circuitry determines an "off" state by "measuring the frequency of the pulses" as required by the amended Claim 24 of the ’833 Patent? The case may turn on expert testimony dissecting whether the accused product's load-sensing method matches this specific, narrowly defined claim element.
- A third question relates to evidence of internal structure: For the ’625 Patent, which claims specific solder-less internal connections, the dispute will depend on whether discovery reveals that the mass-produced Kindle chargers actually employ the precise spring-based contact structure recited in the claims, or if they use a more conventional internal assembly method.