Westinghouse Light Bulbs

Electroluminescence (EL) or the generation of light by electrical excitation of light emitting phosphors has been around for many years. Electroluminescence was first observed in silicon carbide (SiC) by Captain Henry Joseph Round in 1907. Ronde said that the yellow light was produced when a current was passed through the silicon carbide detector. An employee of the Marconi Company and a personal assistant to Guglielmo Marconi, inventor of discussion was his own, with 117 patents to his name at the end of his life.

The following observation recorded electroluminescence of great importance came during the Second World War, if there had been several reports of work in this area during the years 1920 and 1030. In1936 George Destriau, once again noted that the electroluminescence can be produced from this time, zinc sulphide (ZnS) powder after applying an electrical current to produce light, so it. He was told he was Destriau, who first coined the word "Electroluminescence" to describe the phenomenon he observed. Destriau, who worked in the laboratories of Madame Marie Curie in Paris (the Curia to be pioneers in the field of luminescence because of their research on radium), published a report of its findings.

During the Second World War, a considerable amount of research has been conducted on phosphorus in the framework of studies on the radar screen (which was later changed into the television industry in the form of better tubes cathode). research in wartime also work in the transparent conductive film deposition for defrosting windshields of airplanes. This work was later to make possible a new generation of electronic devices. In 1950, GTE Sylvania alleging various coatings, including EL phosphors on the heavy steel plates, ceramic lamps create EL. During this period, most research focused on powder EL phosphors for lighting lamps requiring minimal power and a potentially long life. research funding was cut back when it was determined that the lifetime of the product have been too short (about 500 hours). The first EL thin-film structures were manufactured in the 1950s by Vlasenko and Popkov. These two scientists found that the brightness has increased significantly in the EL devices when they used a thin film of zinc sulphide doped with manganese (ZnS: Mn). Luminance was much higher in thin film EL (TFEL) devices than in powdered substances. These devices were still too unreliable for commercial use.

Several large U.S. companies also conduct research on ELDS in the 1970s, including IBM, GTE, Westinghouse, Aerojet General, and Rockwell. All these companies have realized that ELDS potential advantages over existing LCD technology in the following areas: contrast, multiplexing and angle of vision. The biggest problem that must be solved before mass production could begin ELDS was to increase the reliability of the EL thin film battery. Since devices operating at very high field - about 1.5 MV / cm - there was a high probability they will fail, especially if there was not enough consistency in the stack. Sharp, Tektronix and Lohja Corporation in Finland have been able to solve this problem between 1976 and 1983 using slightly different approaches.

The market introduction in 1985 of the data grid and laptops with screens EL General Sharp and Planar respectively helped build the foundations for the nascent industry laptop at a time when LCDs were not have sufficient brightness and contrast to be used in commercial products. Both Planar and Sharp monochrome ELDS used a phosphor layer containing zinc sulfide doped with manganese (ZnS: Mn). These monitors gave off an orange (orange-yellow) which was brilliant, but also pleasing to the eye.

One of the main weaknesses of ELDS from crystal display (LCD).