20th Century Inventors:
Tungsten Halogen Lamp
© General Electric
Elmer G. Fridrich, 1959
co-holder of U.S. Patent #2,883,571
"Some people said it had been tried - putting halogens in lamps - but it didn't work. My opinion was that halogen had not been tried in this particular configuration, with a material - quartz - that was capable of going to much higher temperatures."
-- Elmer Fridrich, 1996 interview
The research that led to tungsten halogen lamps began as a search at General Electric for a compact heat-lamp. Around 1950, incandescent heat-lamps were large, bulky devices which required large, bulky fixtures. A Nela Park team led by Alton Foote hoped to make much smaller heat-lamps using quartz, which, as Fridrich noted above, can withstand much higher temperatures than ordinary glass.
Unfortunately, the team ran into something that had been a problem since Edison's day. Material (tungsten in this case) boiled off of the filament and deposited on the inner wall of the bulb. This coating darkened the bulb, making it useless. Many ways of combating "bulb-blackening" had been tried over the years, with only limited success. Since the quartz tubes were
narrow, tungsten did not have to migrate far to reach the bulb wall and Foote's team needed a solution.
Team member Elmer Fridrich had started at GE in 1947 as a machinist working the night-shift. Assigned to assist Marvin Pipkin in making equipment to produce new "Q-Coat" (later called "Soft White") bulbs, Fridrich's inventive talent was recognized and he was transferred to research.
In 1953 Fridrich read an article in a scientific journal that discussed chemical purification techniques for tungsten. The method involved the use of halogens, and Fridrich began asking questions. His
colleagues were correct, halogens had been tried without much success. (Waring's "Novak" light-bulb of 1894 used bromine.) Fridrich reasoned, however, that in a
narrow tube, with the filament near the bulb wall, a halogen cycle would work. Using a vacuum system borrowed from
colleague Bill Hodge and with the assistance of Emmett Wiley, Fridrich filled a tubular lamp with a measured amount of iodine -- "and Eureka!, instant success. We pushed it, we kept on running up the wattage and so forth, and it stayed clean, it was beautiful."
As it turned out, much more work was needed before clean lamps could be made consistently. A different solution to the bulb-blackening problem was adopted for GE's quartz heat-lamps. But, management began to see possibilities for a visible-light lamp using Fridrich and Wiley's patent, and put additional researchers onto the problem. Fridrich became less involved with the project and turned his attention to short-arc discharge lamps, advocating their use in automotive headlights. In addition, he invented a disposable fluorescent lamp ballast, and worked on
electroluminescent lamps, flash-bars, and adaptations of the tungsten-halogen lamp which could be used in place of an ordinary light bulb. By the time of his retirement in 1983, Fridrich had obtained over 30 patents for various lighting devices and equipment.