Invalidity dossier
US 5739639
Method and apparatus for operating LED array and charging battery for emergency LED operation including DC boost circuit allowing series connection of LED array and battery
Current assignee: NSI Enterprises Inc
Added 9/23/2026, 4:15:31 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 — US 5,739,639 A
Title: Method and apparatus for operating LED array and charging battery for emergency LED operation including DC boost circuit allowing series connection of LED array and battery
Assignee/Original Assignee: NSI Enterprises Inc (listed assignees also include ABL IP Holding LLC). Inventor: James C. Johnson.
Key dates (per the supplied record): Priority/filing date 1996‑07‑03; publication/grant 1998‑04‑14; Canadian priority filing 1997‑05‑01 (CA2204218C). Listed status: Expired – Lifetime; anticipated expiration 2016‑07‑03.
Purpose: The invention relates generally to emergency lighting systems, particularly circuitry for operating an array of light sources such as LEDs in both normal and emergency modes while allowing battery charging using the same current path. The patent addresses the problem that a single LED array is not readily optimized for both high‑voltage AC and low‑voltage DC operation. It aims to avoid bulky/inefficient line‑frequency transformers and mechanical relays, permitting operation with approximately one‑half watt, as from a single AA battery.
Plain‑language scope: The LED array and battery are connected across the output of a boost circuit output capacitor, enabling series connection of the LED array and battery. This lets the same current‑limited source operate the LED array in both normal AC and DC emergency modes and simultaneously charge/maintain the battery via the same current path. Embodiments include one using a switching power supply as the current‑limited source (FIG. 5) and another combining a switching power supply with current‑limiting capacitors (FIG. 6). A FIG. 1 embodiment places the circuitry on a printed circuit board within a compact exit sign housing. The description notes applicability to other illuminated signage.
Source: https://patents.google.com/patent/US5739639/en
What the excerpt does not establish: Full claim language, the complete description and all figures, the number and exact scope of claims, detailed component values, and the FIG. 2 circuit specifics. The source text was excerpted; omitted portions should be consulted directly. Legal status is expressly disclaimed as an assumption.
Generated 10/1/2026, 9:51:01 PM
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Litigation summary
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Proceedings on file (0)
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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
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Prior art
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Obviousness
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Extensions
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Derivative works
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