Incandescent light bulb: Encyclopedia II - Incandescent light bulb - History of the light bulb

Incandescent light bulb - History of the light bulb

The invention of the light bulb is usually attributed in Britain to Joseph Wilson Swan and in the United States to Thomas Alva Edison (who first marketed the device successfully). However, it is now believed that Heinrich Göbel built functional bulbs three decades earlier. Alexander Nikolayevich Lodygin developed an incandescent light bulb around the same time. Many others also had a hand in the development of a practical device for the production of electric light.

In 1801 Sir Humphry Davy, an English chemist, made platinum strips glow by passing an electric current through them, but the strips evaporated too quickly to make a useful lamp. In 1809 he created the first arc lamp, which he demonstrated to the Royal Institution of Great Britain in 1810, by creating a small but blinding arc between two charcoal rods connected to a battery.

In 1820 a British scientist Warren De la Rue enclosed a platinum coil in a vacuum tube and passed an electric current through it. The design was based on the concept that the high melting point of platinum would allow it to operate at high temperatures and that the evacuated chamber would contain less gas molecules to react with the platinum, improving its longevity. Although it was an efficient design, the cost of the platinum made it impractical for commercial use.

In 1835 James Bowman Lindsay demonstrated a constant electric light at a public meeting in Dundee. He stated that he could "read a book at a distance of one and a half feet". However having perfected the device, to his own satisfaction, he turned to the problem of wireless telegraphy and did not develop the electric light any further.

In 1841 Frederick de Moleyns of England was granted the first patent for an incandescent lamp, with a design using powdered charcoal heated between two platinum wires.

In 1854, the German inventor Heinrich Göbel developed the first 'modern' light bulb: a carbonised bamboo filament, in a vacuum bottle to prevent oxidation. In the following five years he developed what many call the first practical light bulb. The Internet has spread the story of an 1893 lawsuit establishing his priority, but there was no such lawsuit.

Joseph Wilson Swan (1828-1914) was a physicist and chemist born in Sunderland, England. In 1850 he began working with carbonized paper filaments in an evacuated glass bulb. By 1860 he was able to demonstrate a working device but lack of a good vacuum and an adequate supply of electricity resulted in a short lifetime for the bulb and inefficient light. By the mid-1870s better pumps became available, and Swan returned to his experiments. Swan received a British patent for his device in 1878. Swan reported success to the Newcastle Chemical Society and at a lecture in Newcastle in February 1873 he demonstrated a working lamp that utilised a carbon fiber filament, but by 1877 he had turned to slender rods of carbon. The most significant feature of Swan's lamp was that there was little residual oxygen in the vacuum tube to ignite the filament, thus allowing the filament to glow almost white-hot without catching fire. From this year he began installing light bulbs in homes and landmarks in England and by the early 1880s had started his own company.

Across the Atlantic, parallel developments were also taking place. On July 24, 1874 a Canadian patent was filed for the Woodward and Evans Light by a Toronto medical electrician named Henry Woodward and a colleague Mathew Evans, who was described in the patent as a "Gentleman" but in reality a hotel keeper. They built their lamp with different sizes and shapes of carbon held between electrodes in a glass globe filled with nitrogen. Woodward and Evans attempted to commercialize their bulb, but were unsuccessful. Nonetheless, Thomas Edison considered their approach sufficiently promising that he bought rights to both their Canadian and US patents before embarking on his own light bulb development program.

After many experiments with platinum and other metal filaments, Edison returned to a carbon filament that burned for forty hours (first successful test was on October 21, 1879; it lasted 13.5 hours). Edison continued to improve this design. By 1880 he had a device that could last for over 1200 hours using a carbonized bamboo filament.

In January 1882, Lewis Latimer received a patent for the "Process of Manufacturing Carbons," an improved method for the production of light bulb filaments which was purchased by the United States Electric Light Company.

In Britain, the Edison and Swan companies merged into the Edison and Swan United Electric Company (later known as Ediswan which was then incorporated into Thorn Lighting Ltd). Edison was initially against this combination, feeling that his patents would hold up against Swan's claims, but to avoid a court battle, the merger was made. Eventually, Edison acquired all of Swan's interest in the company. Swan sold his United States patent rights to the Brush Electric Company in June 1882. Swan later wrote that Edison had a much greater claim to the light than he.

The United States Patent Office had ruled on October 8, 1883 that Edison's patents were based on the prior art of William Sawyer and were invalid. Litigation continued for a number of years. Eventually on October 6, 1889, a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid.

Edison and his team did not find a commercially workable filament (bamboo) until more than 6 months after Edison filed the patent application. Bamboo continued to be used until 1893, with squirted cellulose being introduced around 1882 and made until at least 1929.

In 1903, Willis Whitnew invented a filament that would not blacken the inside of a light bulb. (Some of Edison's experiments to stop this blackening led to the invention of the electronic vacuum tube) It was a metal-coated carbon filament. In 1906, the General Electric Company was the first to patent a method of making tungsten filaments for use in incandescent light bulbs. The filaments were costly, but by 1910 William David Coolidge (1873-1975) had invented an improved method of making tungsten filaments. The tungsten filament outlasted all other types of filaments and Coolidge made the costs practical.

One of the major problems of the standard electric light bulb is evaporation of the filament. The inevitable variations in resistivity along the filament cause nonuniform heating, with ‘hot spots’ forming at higher resistivity. Thinning by evaporation increases resistivity. But hot spots evaporate faster, increasing their resistivity faster—a positive feedback which ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir suggested that an inert gas, instead of vacuum, would retard evaporation and still avoid combustion, and so ordinary incandescent light bulbs are now filled with nitrogen, argon, or krypton.

A typical filament light bulb lasts about 1000 hours. See the section below, Voltage, light output, and life, for a discussion of the tradeoffs involved in setting a lamp life specification.

Adapted from the Wikipedia article "History of the light bulb", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki