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Effect of Filament Orientation on Incandescent Bulb Life

IP.com Disclosure Number: IPCOM000005472D
Publication Date: 2001-Oct-05
Document File: 1 page(s) / 66K

Publishing Venue

The IP.com Prior Art Database

Abstract

Various studies to identify the factors that affect the life of incandescent light bulbs in motor vehicles have been conducted by many different companies over many, many years.

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Effect of Filament Orientation on Incandescent Bulb Life

Various studies to identify the factors that affect the life of incandescent light bulbs in motor vehicles have been conducted by many different companies over many, many years.

A designed experiment (DOE) was conducted utilizing a fixture containing numerous motor vehicle signal lamp incandescent bulbs mounted to a vibration table.  The vibration table was run at vibration levels determined by real world measurements made from accelerometers mounted directly on the tail lamp bulb in-vehicle and on-road.  In addition, the bulbs in the DOE test were cycled on-and-off per a duty cycle that mimicked results obtained from real world in-vehicle tail lamp bulb usage measurements. 

The figure above shows an incandescent vehicle bulb with its filaments oriented vertically.

Bulb life data was monitored for the bulbs in the DOE test, and subsequent statistical analysis showed that the orientation of the bulb filament was a key factor that affected bulb life.  Specifically, bulbs in the test with their filaments oriented vertically failed sooner than bulbs with other filament orientations.  The plots below, based on the DOE test results, show the predicted bulb failure rates for each of the different filament orientations tested.

Conclusion

The data clearly shows that bulbs with their filaments oriented vertically failed sooner and more often than bulbs with non-vertical filaments.