The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 14, 1998
Filed:
Jul. 03, 1996
James C Johnson, Conyers, GA (US);
NSI Enterprises, Inc., Atlanta, GA (US);
Abstract
Circuitry for operating an array of light emitting diodes such as in an emergency exit sign in a non-emergency AC mode while concurrently charging and maintaining the charge of a low-voltage battery used to drive the array in an emergency mode, the circuitry also allows operation of the same LED array in the emergency mode from the low-voltage battery. The advantages of the invention are realized in part through provision within the circuitry of a boost converter wherein the LED array and the battery are connected across the output of the usual boost circuit output capacitor, thereby allowing connection of the array and the battery in series to simplify operation from line power and to allow the same current limited source to operate the array and simultaneously charge the battery through the same current path. The functions so provided can be embodied in a form which allows all circuitry components including the battery to be mounted on a single, compact substrate such as a printed circuit board.