The parent to the modern fluorescent lamp was invented in the late 1890s by Peter Cooper Hewitt. The Cooper Hewitt lamps were used for photographic studios and industries.
Edmund Germer, Friedrich Meyer, and Hans Spanner patented a high-pressure vapor lamp in 1927. George Inman later teamed with General Electric to create a practical fluorescent lamp, sold in 1938 and patented in 1941. Circular and U-shaped lamps were devised to reduce the length of fluorescent light fixtures. The first fluorescent bulb and fixture were displayed to the general public at the 1939 New York World's Fair.
The helical (three-dimensional spiral) CFL was invented in 1976 by Edward Hammer, an engineer with General Electric, in response to the 1973 oil crisis. Although the design met its goals, and it would have cost GE about US$25-million to build new factories to produce the lamps, the invention was shelved. The design eventually was copied by others. In 1995, helical lamps, manufactured in China, became commercially available; Their sales have steadily increased.
In 1980, Philips introduced its model SL, which was a screw-in lamp with integral ballast. The lamp used a folded T4 tube, stable tri-color phosphors, and a mercury amalgam. This was the first successful screw-in replacement for an incandescent lamp. In 1985 Osram started selling its model EL lamp, which was the first CFL to include an electronic ballast.
Development of fluorescent lamps that could fit in the same volume as comparable incandescent lamps required the development of new, high-efficacy phosphors that could withstand more power per unit area than the phosphors used in older, larger fluorescent tubes.
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