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
US5739639A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 3, 1996 |
| Grant date | Apr 14, 1998 |
| Priority date | — |
| Expiry date | Jul 3, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02J9/061
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.