#600: Lifebulb

No matter what you might think about some of Edison’s attitudes, you have to admit that he was highly creative.

The incandescent bulb, which he helped to develop commercially, is way out of favour these days. This is for a variety of different reasons including energy efficiency (only ~10% conversion to light), cost of manufacture and reliability.

Today’s invention takes a second look at this old technology and addresses the latter aspects of its design. Imagine a cylindrical glass ‘envelope’ with the usual, low pressure inert gas inside. On the inside surface of the cylinder is loosely bonded a helix of filament wire. One end of the cylinder admits a sealed rotor which allows the two contact wires it carries to drive current through a fixed length of filament. As one section burns out over time, so the rotor, when turned a little (via a screw thread), allows the contacts to connect across the next section of filament. A smarter version might aim to vary over time the length of filament between contacts to as to make use of the remaining, unburnt sections -although this would cause a variation in light output each time.

Much greater mechanical strength, miniaturisation potential and the ability to bypass burned-out filament sections would result in greatly enhanced longevity -with only a marginal increase in manufacturing costs.

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