1:00-cv-11049
VLT Corp v. Lucent Technologies
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: VLT, Inc. (California) and Vicor Corporation (Delaware)
- Defendant: Lucent Technologies Incorporated (Delaware), Tyco Electronics Power Systems, Inc. (Nevada), and Tyco International Ltd. (Bermuda)
- Plaintiff’s Counsel: Goodwin Procter LLP; Fish & Richardson P.C.
- Case Identification: 1:00-cv-11049, D. Mass., 06/19/2001
- Venue Allegations: Plaintiffs allege venue is proper based on Defendants distributing their products in the District of Massachusetts.
- Core Dispute: Plaintiffs allege that Defendants’ DC-to-DC power converters infringe a patent related to an efficient method for resetting a converter's transformer core.
- Technical Context: The technology concerns high-frequency, single-ended forward power converters, a fundamental component in electronic devices for converting DC voltage levels, where efficiency and power density are critical market drivers.
- Key Procedural History: The patent-in-suit, RE 36,098, is a reissue of U.S. Patent No. 4,441,146. The complaint alleges that Defendant Lucent was notified of the original patent in 1995, years before the reissue and the filing of the suit, which may be relevant to willfulness. Defendant Tyco Power is the successor-in-interest to Lucent's Power Systems business.
Case Timeline
| Date | Event |
|---|---|
| 1982-02-04 | Priority Date for RE 36,098 ('146 application filing) |
| 1984-04-03 | Original U.S. Patent No. 4,441,146 issues |
| 1995-10-05 | Plaintiff Vicor allegedly informs Defendant Lucent of patent |
| 1999-02-16 | U.S. Reissue Patent No. RE 36,098 issues |
| 2000-11-13 | Tyco Int'l announces agreement to acquire Lucent's Power Systems business |
| 2000-12-29 | Tyco completes acquisition of Lucent's Power Systems business |
| 2001-06-19 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Reissue Patent No. RE 36,098 - Optimal Resetting Of The Transformer's Core In Single-Ended Forward Converters
The Invention Explained
- Problem Addressed: The patent addresses a fundamental inefficiency in "single-ended forward" DC-to-DC converters. Prior methods for resetting the transformer’s magnetic core between power cycles either limited the converter’s operational range and created voltage stress (RE 36,098, col. 2:26-40), or they dissipated the transformer’s magnetic energy as heat, which reduces power efficiency and density (RE 36,098, col. 3:19-27).
- The Patented Solution: The invention proposes a "magnetizing current mirror" circuit, comprising a capacitor and an auxiliary switch, that works during the main switch's "OFF" period (RE 36,098, col. 4:6-16). Instead of wasting the transformer's stored magnetic energy, this circuit forms a resonant loop that recycles the energy, creating a "mirror image" of the magnetic flux (RE 36,098, col. 4:10-14). This approach is non-dissipative, maximizes the usable magnetic flux swing of the core, and minimizes voltage stress on the power-switching components, thereby improving efficiency and power density (RE 36,098, col. 4:21-38).
- Technical Importance: This method allows for the design of smaller, more efficient, and more robust power converters that can operate over a wider range of input voltages and loads, a key requirement in the electronics industry (RE 36,098, col. 3:12-18).
Key Claims at a Glance
- The complaint asserts independent claims 1 and 5 (Compl. ¶16).
- Independent Claim 1 recites an apparatus for recycling magnetizing energy in a forward converter, comprising:
- A storage capacitor.
- An auxiliary switch connected in series with the storage capacitor.
- A switch control circuit operating the auxiliary switch with specific timing logic: the auxiliary switch is opened before the primary switch's "ON" period, remains open during the "ON" period, and is closed after the "ON" period.
- The complaint does not explicitly reserve the right to assert dependent claims but makes a general allegation of infringement of "one or more claims" (Compl. ¶19).
III. The Accused Instrumentality
Product Identification
The complaint identifies DC-to-DC converter models JW150A1 and FW300C1, which were designed and sold by Lucent's Power Systems business unit and subsequently by Tyco Power after its acquisition of that unit (Compl. ¶¶14-16).
Functionality and Market Context
The complaint alleges these products are "single-ended forward converters" (Compl. ¶16). Exhibit C, an advertisement for predecessor AT&T power modules, promotes their high power density, offering "up to 150 useable watts in a small 2.4 x 2.28 x 0.5 inch package" (Compl., Ex. C, p. 27). The advertisement, depicting a compact, board-mounted power module, highlights the commercial importance of achieving high power output in a small form factor, a central objective of the patented technology (Compl., Ex. C, p. 27). The complaint alleges these converters compete directly with products manufactured by Vicor (Compl. ¶21).
IV. Analysis of Infringement Allegations
The complaint makes a conclusory allegation that the accused products contain all limitations of the asserted claims but does not provide a detailed mapping of product features to claim elements (Compl. ¶16). The following chart summarizes the infringement theory as can be inferred from the complaint's general allegations against the accused "single-ended forward converters."
RE 36,098 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| In a single ended forward converter... circuitry for recycling the magnetizing energy stored in said transformer to reset it... comprising: | The accused JW150A1 and FW300C1 products are alleged to be single-ended forward converters that incorporate circuitry to reset the transformer core. | ¶16 | col. 8:52-57 |
| a storage capacitor; | The accused converters are alleged to contain a storage capacitor as part of their transformer reset circuitry. | ¶16 | col. 5:21-22 |
| an auxiliary switch connected in series with said storage capacitor; | The accused converters are alleged to contain an auxiliary switch connected in series with the storage capacitor. | ¶16 | col. 5:21-23 |
| a switch control circuit operating said auxiliary switch in accordance with a control logic such that (a) said auxiliary switch is opened prior the ON period of said primary switch, (b) said auxiliary switch remains open throughout the ON period of said primary switch, (c) said auxiliary switch is closed after the ON period of said primary switch. | The accused converters are alleged to contain a control circuit that operates an auxiliary switch according to the claimed timing logic relative to the primary power switch's cycle. | ¶16 | col. 5:27-31 |
- Identified Points of Contention:
- Evidentiary Questions: The primary question will be evidentiary: what is the actual circuit topology and method of operation of the accused JW150A1 and FW300C1 converters? The complaint does not provide schematics or a technical analysis of the accused products' internal workings. The case will depend on evidence obtained during discovery regarding whether the accused products contain a "storage capacitor," an "auxiliary switch," and a "switch control circuit" that operates according to the specific timing logic recited in claim 1.
- Scope Questions: A potential dispute may arise over the definition of the claimed components. For example, if the accused device uses a single, complex integrated circuit to manage power conversion, a question will be whether distinct functional blocks within that IC can be identified as the claimed "auxiliary switch" and "switch control circuit."
V. Key Claim Terms for Construction
The Term: "auxiliary switch"
Context and Importance: The claim requires an "auxiliary switch" that is distinct from the "primary switch" used for power transfer. Its definition is critical because infringement hinges on finding a second, separate switch in the accused device dedicated to the patented reset function. Practitioners may focus on whether a multi-function component or a different type of circuit element in the accused device can meet this limitation.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent does not limit the term to a specific type of switch, referring to it as a "solid state switch" (RE 36,098, col. 3:64-65). Claim 5 specifically claims a "MOSFET transistor with an integral reverse diode," suggesting that the general term "auxiliary switch" in claim 1 is not necessarily limited to that specific embodiment (RE 36,098, col. 9:8-10).
- Evidence for a Narrower Interpretation: The specification consistently depicts the auxiliary switch (21) as a discrete component separate from the primary switch (10) and operating under a distinct control logic from a control circuit (22) (RE 36,098, Fig. 4a; col. 5:21-23). This could support an argument that "auxiliary switch" must be a structurally separate component from the primary switch.
The Term: "a switch control circuit operating said auxiliary switch in accordance with a control logic such that... [the switch] is opened prior the ON period... remains open throughout the ON period... and is closed after the ON period"
Context and Importance: This term defines the precise, three-part operational sequence of the auxiliary switch. The infringement analysis will turn on whether the accused converters' control systems follow this exact timing sequence. Any deviation could support a non-infringement argument.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent's objective is to provide an "optimal reset mechanism" that avoids the "dead time" of prior art (RE 36,098, col. 2:16-20; col. 3:55-57). A party might argue that any control logic that achieves this goal by operating the reset circuit only during the OFF period falls within the spirit of the invention.
- Evidence for a Narrower Interpretation: The claim language is highly specific, laying out a clear three-step sequence. The detailed description states this logic is a "requiring" feature of the control circuit (RE 36,098, col. 5:27-31). The patent also notes that a small delay between the auxiliary switch opening and the primary switch closing is "useful" but still frames this within the claimed sequence, suggesting the sequence itself is not flexible (RE 36,098, col. 7:7-11).
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Defendants are contributing to or inducing infringement by "manufacturing, using, selling, and/or offering for sale their products" (Compl. ¶19). No specific facts, such as the provision of user manuals or instructions, are alleged to support the knowledge and intent elements of these claims.
- Willful Infringement: The complaint alleges that Defendant Lucent had pre-suit knowledge of the technology via a letter from Vicor dated October 3, 1995, which identified the predecessor patent (Compl. ¶17). It further alleges on information and belief that Tyco was aware of the '098 patent before its acquisition of Lucent's business (Compl. ¶17). These allegations of specific, pre-suit knowledge form the basis for the willfulness claim (Compl. ¶20).
VII. Analyst’s Conclusion: Key Questions for the Case
This dispute will likely center on two key questions:
A core evidentiary question: Can Plaintiffs produce evidence from the internal architecture of the accused JW150A1 and FW300C1 converters to demonstrate the presence of a distinct "auxiliary switch" and "control circuit" that performs the precise, three-part timing logic required by claim 1? The bare allegations in the complaint will need to be substantiated with technical evidence.
A key claim construction question: Will the term "auxiliary switch" be construed to require a structurally separate component, or can it be met by a functional block within a more complex integrated circuit? The answer will determine whether modern, highly integrated power converter designs fall within the scope of the claims.