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Following the development of the original infrared quartz lamp by GE of America in the mid 1950s, its design was improved slightly by adding a halogen gas filling following that company's subsequent invention of the halogen quartz lamps in 1958. During the next few decades they found many applications, but almost always confined to industrial heating and drying. The next major development arrived in the 1980s when Thorn EMI of the UK developed two new applications - infrared spaceheating, and infrared cooking.
Thorn EMI owned not only a lighting division, but also several domestic applicance businesses including Tricity, which was engaged in the manufacture of electric cookers. A joint project was started in the early 1980s under the leadership of Alex Halberstadt of the Enfield laboratories, to develop quartz halogen lamps for cooking hobs. Halogen lamps feature much lower thermal inertia than conventional electric resistance heaters, and introduced the novel feature of near instant heat and much quicker regulation of temperature. This allowed electric cookers to compete for the first time with the speed and controllability of gas.
In the original design an array of four short linear lamps were placed behind an infrared-transmitting heat resistant glass-ceramic plate invented by Corning of USA, which served as a tough surface for the cooking hob. This particular lamp is a later model which features a side reflector of alumina powder flamesprayed onto the quartz tube. Alumina is an excellent reflector of shortwave infrared radiation, and allowed elimination of an external metallic reflector below the lamps such that the lamps could be spaced closer together for better heating uniformity. |