Invalidity dossier
US 5688042
LED lamp
Current assignee: ABB Installation Products International LLC
Added 9/23/2026, 2:14:09 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US5688042A ("LED lamp")
US5688042A is titled "LED lamp," invented by Abolfazl Madadi, Morteza Showleh, and David J. Rycroft, and originally assigned to Lumacell Inc. The application (US08/560,440) was filed November 17, 1995, which is also the priority date; it was granted and published November 18, 1997. A corresponding Canadian priority filing (CA2190315A) is dated November 14, 1996. The record lists the current assignee as ABB Installation Products International LLC, with earlier reassignments to Thomas & Betts International, Inc. (2001) and Thomas & Betts International LLC (2014); legal status is "Expired – Lifetime," with anticipated expiration November 17, 2015. These are recitations of the record, not conclusions.
Purpose. The patent addresses lighted exit and emergency signs, which typically used 15–25 watt incandescent or compact fluorescent lamps — a significant power draw, especially on battery backup. Prior LED approaches arranged diodes in rows matching stencil lettering, producing multiple bright spots even through diffusers, and existing LED replacement lamps were highly directional and required careful rotational positioning so the board face paralleled the stencil.
Plain-language scope. The claimed lamp has a base configured to engage an electrical socket, with outer conductive elements and internal contacts. Multiple circuit boards extend from the base in an array of triangular cross section, each board carrying spaced LEDs on its outward surface. Power transfer circuitry connects the boards' conductors to the base contacts and includes AC-to-DC conversion, using a cylindrical film AC input capacitor extending axially between base and boards. A tubular light-transmitting housing encloses the boards; wire clips seated in board notches hold the array; base apertures allow air circulation. The lamp may use candelabra, medium, intermediate, bayonet, or PL (bi-pin) bases and is shown in a sign having one or two indicia plates with the socket between them.
Not established by this excerpt. The excerpt omits full claim text, detailed description, drawings, and the complete reference list; it provides no litigation, validity, or prior-art analysis.
Source: https://patents.google.com/patent/[US5688042](/patent/US5688042)/en
Generated 10/1/2026, 9:52:27 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
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
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.