The FED design is perhaps the ultimate in analog display technology. FEDs are similar to CRTs in that an FED illuminates phosphors by means of varying the electron voltages applied to them. However, instead of one electron gun/beam per phosphor type, FEDs have many. Hundreds of thousands or millions of tiny electron guns called microtip emitters are built into columns along cathode electrodes, which set on the display's back plate. Structures similar to a shadow mask called "gate electrodes" run across the microtips. These horizontal and vertical structures form a matrix similar to that found in many digital displays, which control pixel selection of emitted electrons.
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| Figure 2 - Field emission display |
Electrons flow through the cathode electrode and a resistive layer on top of it, reaching the microtips where they are emitted. These electrons are instantly attracted to the phosphors between the microtips and display's anode (or ITO layer) as a result of its much higher electrical charge. This phenomenon is defined as field emission. As in a CRT monitor, when the electrons strike the phosphor, colored light is produced. As the phosphors are no more than 2.5 mm away from the microtips, the overall size of these displays is extremely thin, with prototype 5.7" color models being less than 0.5" thick.
The refresh rate of these displays is at least three times that of other analog technologies. The result is an extremely bright image without any flicker whatsoever. This type of monitor also allows for wide viewing angles while still maintaining an acceptable image, something flat panel LCD displays do not.
The disadvantage of FEDs will be the same ones held by many other display technologies when first commercially released. One, they will be expensive. Two, they will be smaller than practical. FED pioneer Pixtech is, at the time of this writing, working on a 15" model for use with home computers or as a television monitor, while the release of a 5.7" model is imminent.
Sections:
- Display Technologies
- Introduction - Analog and Digital
- Analog Technologies
- Cathode Ray Tube - CRT
- Field Emission Display - FED
- Image Light Amplifier - ILA
- Digital Technologies
- Liquid Crystal Display - LCD
- Plasma Display
- Digital Light Processor™ - DLP™
- Direct, Direct Drive, or Digital Image Light Amplifiers - D-ILA™
- Conclusion