Invalidity dossier
US 8421366
Illumination device including LEDs and a switching power control system
Current assignee: Ilumisys Inc
Added 9/23/2026, 2:10:16 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US8421366B2
Title: Illumination device including LEDs and a switching power control system
Patent number / application: US8421366B2; Application US12/821,769, filed 2010-06-23.
Assignee: Originally Ilumisys Inc; reassigned to Altair Engineering, Inc. (2010-06-24) and then to Ilumisys, Inc. (2012-04-02).
Inventors: Francis Palazzolo; John Ivey.
Key dates: Priority date 2009-06-23 (provisional 61/219,627, filed Jun. 23, 2009); publication 2013-04-16. Status listed as Active, adjusted expiration 2031-08-26.
Purpose: LEDs generally run on DC, so AC-powered LED fixtures need AC-to-DC conversion. Known converters are described as impractical for some LED applications due to size and cost, since passive components such as capacitors and inductors grow larger as operating voltages increase. The patent addresses this with a switching power control system, including use with existing fluorescent lamp fixtures having a conventional ballast.
Plain-language scope: The illumination device has LEDs, an AC input, a full-wave rectifier producing a rectified voltage output, and a power converter with a switching element coupled to that rectified output. The improvement is a feedback circuit that determines the average current across the LEDs and inverts a signal representing that average current to supply a switching signal to the switching element. The result, over a range of operating points, is inverted behavior: increasing current drawn into the power converter decreases LED power, and decreasing that current increases LED power. In a further embodiment for existing fluorescent fixtures, the feedback circuit uses a duty cycle — raising the duty cycle decreases the LED output current, and lowering it increases that current. A corresponding method of controlling the feedback circuit is also described: determining the average LED current, inverting its signal, and providing the switching signal to the switching element.
Source: https://patents.google.com/patent/[US8421366](/patent/US8421366)/en
What the excerpt does not establish: The supplied text is an excerpt; it omits the full description, all claims, the drawings' contents, examiner citations, and any prior-art references beyond U.S. Pat. No. 7,049,761 mentioned in the background. It therefore does not establish the exact claim scope, whether the listed legal status is accurate, or the content of foreign counterparts (WO2011005579A2, CA2765200A1, EP2446715A4).
Generated 10/1/2026, 9:52:30 PM
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Litigation summary
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PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.