History
Piezoelectricity was discovered by Jacques and Pierre Curie in 1880. Paul Langevin first investigated quartz resonators for use in sonar during World War I. The first crystal-controlled oscillator, using a crystal of Rochelle salt, was built in 1917 and patented in 1918 by Alexander M. Nicholson at Bell Telephone Laboratories, although his priority was disputed by Walter Guyton Cady. Cady built the first quartz crystal oscillator in 1921. Other early innovators in quartz crystal oscillators include G. W. Pierce and Louis Essen.
Quartz crystal oscillators were developed for high-stability frequency references during the 1920s and 1930s. By 1926 quartz crystals were used to control the frequency of radio broadcasting stations and were popular with amateur radio operators. In 1928, Warren Marrison (of Bell Telephone Laboratories) developed the first quartz crystal clock. This invention replaced the escapement and pendulum (as the timing reference), relying instead on the natural vibrations occurring in the quartz crystal as the oscillator. This improved timing accuracies to 1 sec in 30 years (or 30 ms/year). Utilizing the early work at Bell Labs, AT&T eventually established their Frequency Control Products division, later spun off and known today as Vectron International.
A number of firms started producing quartz crystals for electronic use during this time. Using what are now considered primitive methods, about 100,000 crystal units were produced in the United States during 1939. Through World War 2 crystal were made from natural quartz crystals, virtually all from Brazil. Shortages of crystals during World War 2 caused by the demand for accurate frequency control of military and naval radios and radars spurred postwar research into culturing synthetic quartz, and by 1950 a hydrothermal process for growing quartz crystals on a commercial scale was developed at Bell Laboratories. By the 1970s virtually all crystals used in electronics were synthetic.
In 1968, Juergen Staudte invented a process for manufacturing quartz crystal oscillators while working at North American Aviation (now Rockwell). Staudte patented his invention, which used a photolithographic process that is similar to the way integrated circuits are made. In 1970 he left North American Aviation to start his own company, Statek, in Orange, California. Statek began manufacturing and marketing the quartz oscillators in 1971.
Although crystal oscillators still most commonly use quartz crystals, devices using other materials are becoming more common, such as ceramic resonators.
Read more about this topic: Crystal Oscillator
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