Vacuum fluorescent display
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A vacuum fluorescent display (VFD) is a type of display used primarily on consumer-electronics equipment such as video cassette recorders. Unlike liquid crystal displays, a VFD emits a very bright light with clear contrast.
The device consists of a cathode (filaments), anodes (phosphor) and grids encased in a glass envelope under a high vacuum condition. The cathode is made up of fine tungsten wires, coated by alkaline earth metal oxides, which emit electrons. These electrons are controlled and diffused by the grids, which are made up of thin metal.
A main disadvantage of this display was that it consumed too much power to work effectively. This was considered a disadvantage with battery-operated equipment like calculators and this display ended up being used primarily for equipment that worked primarily off the AC supply or for automotive applications where the power was often maintained by the vehicle's engine or constantly-charged battery.
During the 1980s, this display was used for automotive applications, especially when carmakers were, in that period, dabbling with digital displays for vehicle instruments like the speedometer. A good example of this were the high-end Subaru cars made in the early 80s. The reason this technology was considered appropriate for electronic displays in the automotive context was because the displays were very bright.
External link
- Vacuum Fluorescent Display (VFD) (including How to drive the filament) (http://hem.passagen.se/communication/vfd.html)
- VFD-Page of Futaba (widely known manufacturer of VFDs) (http://www.futaba-eu.com/docs/vfd.htm)