Thomas Edison

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The Incandescent Light Bulb

Thomas Edison

• In his 84 years, Thomas Edison acquired a record number of 1,093 patents (singly or jointly) and was the driving force behind such innovations as the phonograph, the incandescent light bulb and one of the earliest motion picture cameras.

In 1809, an English chemist, Humphrey Davy, started the journey to the invention of a practical incandescent light source. He used a high power battery to induce currents between two charcoal strips.

In 1820, Warren De la Rue made the first known attempt to produce an incandescent light bulb. He enclosed a platinum coil in an evacuated tube and passed an electric current through it. Although it was an efficient design, the cost of the platinum made it impractical for commercial use.

First Attempts

Research & Development

• In 1878, Edison focused on inventing a safe, inexpensive electric light to replace the gaslight--a challenge that scientists had been grappling with for the last 50 years.

• Edison set up the Edison Electric Light Company and began research and development.

The Carbon Filament

• After many experiments with platinum and other metal filaments, Edison returned to a carbon filament. The first successful test lasted 13.5 hours. Edison continued to improve this design and by November 4, 1879, filed for a U.S. (granted on January 27, 1880) for an electric lamp using "a carbon filament or strip coiled and connected to platina contact wires".

Bamboo

• A few months after receiving his patent Edison and his team discovered a carbonized bamboo filament that could last over 1,200 hours. The idea of using this raw material originated from Edison's examination of a few threads from a bamboo fishing pole while relaxing on the shore of Battle Lake in the present-day state of Wyoming.

"We will make electricity so cheap that only the rich will burn candles.”

-Thomas Edison