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Browse Prior Art Database

Fail Safe Light Bulb

IP.com Disclosure Number: IPCOM000090704D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Gaston, CA: AUTHOR

Abstract

Two filaments are mounted in parallel in a light bulb envelope in such a manner that filament 1, by choice of either material or resistance or both, supplies the greater amount of light output. The second filament 2 is chosen to be of a material, or a resistance by thickness of the filament, to provide a lower light output but a very long life. This second filament can also be chosen to provide a light output of different color than that of the primary light filament 1. If filament 1 burns out, filament 2 continues to operate. By its reduced light output or different color, there is an indication that filament 1 has burned out. This bulb thus serves as a fail-safe warning bulb for on-off indicating uses and as an emergency output bulb in regular use when filament 1 burns out.

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Fail Safe Light Bulb

Two filaments are mounted in parallel in a light bulb envelope in such a manner that filament 1, by choice of either material or resistance or both, supplies the greater amount of light output. The second filament 2 is chosen to be of a material, or a resistance by thickness of the filament, to provide a lower light output but a very long life. This second filament can also be chosen to provide a light output of different color than that of the primary light filament 1. If filament 1 burns out, filament 2 continues to operate. By its reduced light output or different color, there is an indication that filament 1 has burned out. This bulb thus serves as a fail-safe warning bulb for on-off indicating uses and as an emergency output bulb in regular use when filament 1 burns out.

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