Voltstar Tech Inc v. TXS Industrial Design Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Voltstar Technologies, Inc. (Illinois)
  • Defendant: TXS Industrial Design, Inc. d/b/a Brandstand Products (Texas)
  • Plaintiff's Counsel: Harris, Finley & Bogle, P.C.; SRIPLAW, P. A.
• Case Identification: 3:26-cv-01051, N.D. Tex., 06/02/2026
• Venue Allegations: Venue is asserted on the basis that Defendant has committed acts of infringement within the district and is subject to personal jurisdiction there.
• Core Dispute: Plaintiff alleges that Defendant's "Cubiespot" line of wireless charging products infringes two patents related to energy-saving technology that automatically reduces power consumption when a connected device is fully charged or disconnected.
• Technical Context: The technology addresses the reduction of "phantom load" (standby power) in consumer electronics chargers, a field driven by energy efficiency standards and consumer demand for "green" technology.
• Key Procedural History: The '648 Patent is a continuation of the '833 Patent. Both patents-in-suit underwent post-grant challenges (Inter Partes Reexamination and/or Review) that resulted in the cancellation or disclaimer of many original claims and the amendment of the surviving asserted claims. These amendments narrowed the claims to focus on a specific method of load sensing: measuring the frequency of pulses from transformer control circuitry. This extensive prosecution history will likely be central to claim construction and may significantly narrow the scope of the asserted claims.

Case Timeline

Date	Event
2008-05-27	'833 Patent Priority Date
2008-10-15	'648 Patent Priority Date
2011-03-22	'833 Patent Issue Date
2011-06-14	'648 Patent Issue Date
2015-12-01	'648 Patent Reexamination Certificate (C1) Issued
2017-11-03	'833 Patent Reexamination Certificate (C1) Issued
2022-01-21	'833 Patent Inter Partes Review Certificate (K1) Issued
2026-06-02	Complaint Filing Date

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

U.S. Patent No. 7,910,833 - "Energy-Saving Power Adapter/Charger"

• Issued: March 22, 2011

The Invention Explained

• Problem Addressed: The patent addresses the problem of "phantom load," which is the residual power consumed by power adapters and chargers even when the host electronic device is disconnected, shut off, or fully charged '833 Patent, col. 1:65-2:4 This leads to wasted energy on a massive scale '833 Patent, col. 2:4-13
• The Patented Solution: The invention is a power device, such as a charger, that includes circuitry to automatically shut off or de-power itself when it detects that the connected electronic device is no longer drawing power '833 Patent, abstract As narrowed during reexamination, the patented solution utilizes a "load sensing portion" that determines the power draw by "measuring the frequency of the pulses" from the transformer's control circuitry to determine when to enter the "off" state '833 C1 Certificate, claim 24 The circuitry includes components like a primary switch and gain and level detection, which can be implemented in an integrated circuit '833 Patent, Fig. 11
• Technical Importance: This approach provided a method to create "zero-energy" chargers that comply with increasing government energy-efficiency standards without requiring users to manually unplug them from the wall '833 Patent, col. 2:14-29

Key Claims at a Glance

• The complaint asserts independent Claim 24 (as amended during reexamination) and dependent Claims 33 and 36 ('Compl. ¶48).
• Essential elements of independent Claim 24 include:
  • A first portion for receiving input power and a second portion for delivering output power.
  • Power circuitry for converting the power and determining an "off" state.
  • Switching circuitry to electrically activate the power circuitry to the "on" state.
  • A "load sensing portion" that is operable to sense one or more pulses and determine the power or load being drawn from the power device "by measuring the frequency of the pulses." '833 C1 Certificate, claim 24
• The complaint reserves the right to assert other claims ('Compl. ¶21).

U.S. Patent No. 7,960,648 - "Energy-Saving Cable Assemblies"

• Issued: June 14, 2011

The Invention Explained

• Problem Addressed: The '648 Patent also targets phantom load but focuses on a solution integrated into a cable assembly, noting that the power input (e.g., the charger brick plugged into a wall) is often in a difficult-to-reach location, discouraging users from unplugging it '648 Patent, col. 3:5-12
• The Patented Solution: The patent describes a cable assembly with integrated switch circuitry that can be located remotely from the power source, often near the connector for the electronic device '648 Patent, abstract The circuitry automatically disconnects input power when an "on-state" signal is no longer received from the electronic device '648 Patent, col. 4:28-39 Following reexamination, the asserted claims were amended to specify that this function is achieved via "pulse monitoring circuitry operable to monitor the frequency of pulses" to drive the switch '648 C1 Certificate, claim 39
• Technical Importance: This design improves user convenience by placing the control mechanism at the user's fingertips (at the device-end of the cable) while still achieving a "zero-waste" state at the power source '648 Patent, col. 3:12-20

Key Claims at a Glance

• The complaint asserts Claims 31, 32, and 39, which were amended during reexamination ('Compl. ¶53). Independent claim 39 (as amended) is representative.
• Essential elements of independent Claim 39 (incorporating base claim 34, which was cancelled) include:
  • An input portion for connecting to a power source.
  • A converter portion with converter circuitry.
  • Switch circuitry for controlling an on/off state.
  • "pulse monitoring circuitry operable to monitor the frequency of pulses and drive the switch circuitry based thereon." '648 C1 Certificate, claim 39
• The complaint reserves the right to assert other claims ('Compl. ¶21).

III. The Accused Instrumentality

Product Identification

• Defendant's "Cubiespot-branded Wireless Charging devices," including the Cubiespot Wireless Charger, CubiePoint Wireless Charging Pad, CubiePoint Tabletop Wireless Charging Station, CubieDot Tabletop Wireless Charging Station, CubieVia Tabletop Power Strip, CubieDuo Wireless Charging Hotel Alarm Clock, and CubieTrio/Trio+ Magnetic Wireless Charging Hotel Alarm Clock with various features ('Compl. ¶15; Compl. ¶¶24-44).

Functionality and Market Context

• The accused products are described as Qi-compliant wireless chargers that use electromagnetic induction to charge devices like mobile phones ('Compl. ¶¶16-19). An image of a Cubiespot wireless charging pad illustrates the basic form factor of the accused technology ('Compl. p. 4).
• The complaint alleges these chargers contain "internal monitoring and switch circuitry" to detect when a device is fully charged or requires charging ('Compl. ¶20). Critically, the complaint alleges this circuitry includes 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, and to determine an 'off' state for the device" ('Compl. ¶20). This functionality is allegedly present across the product line, from simple pads to more complex alarm clock units like the CubieDuo ('Compl. p. 10).

IV. Analysis of Infringement Allegations

'833 Patent Infringement Allegations

Claim Element (from Independent Claim 24)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a first portion for receiving electrical input power from a source... a second portion for delivering electrical output power to the electronic device	The Cubiespot chargers are connected between a source of AC power (a wall outlet) and a mobile device to be charged ('Compl. ¶16).	¶16	col. 6:36-44
power circuitry for converting the input power voltage to the output power voltage	The chargers convert AC power to provide inductive power for charging a device's battery ('Compl. ¶19).	¶19	col. 7:4-11
switching circuitry operable to electrically activate the power circuitry to the "on" state	The chargers comprise one or more internal switches (mechanical or electrical) that control the flow of current based on the charge-status of the battery ('Compl. ¶20).	¶20	col. 10:3-9
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 chargers allegedly utilize 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" ('Compl. ¶20).	¶20	col. 10:9-16

'648 Patent Infringement Allegations

Claim Element (from Independent Claim 39)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
an input portion for connection with power source for receiving input electrical power	The accused chargers connect to a power source such as a wall outlet ('Compl. ¶16).	¶16	col. 10:46-56
a converter portion including converter circuitry for converting electrical power	The products function as wireless chargers, converting input power for inductive charging of mobile devices ('Compl. ¶19).	¶19	col. 7:27-35
switch circuitry for controlling an on and an off state for the system	The chargers allegedly use "internal monitoring and switch circuitry features" to control power flow based on the device's charging status ('Compl. ¶21).	¶21	col. 7:4-16
pulse monitoring circuitry operable to monitor the frequency of pulses and drive the switch circuitry based thereon	Plaintiff alleges the chargers use a "load sensing portion, which senses the frequency of pulses... to determine the load being drawn, and to determine an 'off' state" ('Compl. ¶20).	¶20	col. 15:5-13

• Identified Points of Contention:
  • Technical Question: The central factual dispute will likely be whether the accused chargers actually "measur[e] the frequency of the pulses" to determine load, as alleged in the complaint ('Compl. ¶20) and required by the amended claims. The defense may argue that its products use a different load-sensing technique, such as measuring voltage, current magnitude, or pulse width, which would not meet this specific claim limitation.
  • Scope Question: Given that the "frequency of pulses" language was added during reexamination to overcome prior art, its interpretation will be critical. The court will need to determine if the specific electronic method used in the accused chargers falls within the scope of this term, a scope that may be narrowly defined by the prosecution history.

V. Key Claim Terms for Construction

• The Term: "measuring the frequency of the pulses" '833 C1 Certificate, claim 24 / "monitor the frequency of pulses" '648 C1 Certificate, claim 39
• Context and Importance: This language was added to the key independent claims of both patents during post-grant proceedings, presumably to distinguish them from prior art and secure their validity. As such, the definition of this phrase is paramount. Practitioners may focus on this term because the entire infringement analysis likely depends on whether the accused products' load-sensing method is proven to be a form of frequency measurement.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: A party seeking a broader scope may point to specification passages that describe monitoring "pulses" from a transformer secondary to drive a switch, arguing that "frequency" is just one way to characterize these pulses and that other pulse-based measurements should be included '833 Patent, col. 10:9-16
  • Evidence for a Narrower Interpretation: A party seeking a narrower scope will argue that the explicit addition of the word "frequency" during reexamination was a deliberate and binding choice to surrender any broader scope covering other pulse-monitoring techniques (e.g., measuring amplitude or duration). This creates a strong case for applying prosecution history estoppel, limiting the term to a literal measurement of pulse recurrence over time.

VI. Other Allegations

• Indirect Infringement: The complaint does not contain specific counts for indirect or contributory infringement, focusing its factual allegations on Defendant's direct infringement through making, using, and selling the accused products ('Compl. ¶¶47; Compl. ¶52).
• Willful Infringement: The complaint requests a finding of willful infringement and enhanced damages in its prayer for relief ('Compl. Prayer for Relief ¶C). However, the body of the complaint does not currently plead specific facts to support this claim, such as allegations of pre-suit knowledge of the patents or egregious conduct.

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

• A central question will be one of technical evidence: Can the Plaintiff prove, through discovery and expert testimony, that the accused Brandstand chargers perform load sensing by specifically "measuring the frequency of the pulses" from their internal circuitry? This is a highly specific technical allegation that will require detailed evidence of the accused products' operation.
• The case will also turn on a question of claim scope defined by prosecution history: Given that the "measuring the frequency of the pulses" limitation was added to the asserted claims of both patents to overcome rejections during post-grant proceedings, the doctrine of prosecution history estoppel may significantly narrow its interpretation. A key legal battle will be over whether the defendant's technology, even if pulse-based, falls outside the narrow definition that the patentee established to save its claims.