Are Feds in Your Future?

  • While the flat panel display technology alternatives seem to be limited to TFT-LCDs or plasmas, some video purists still lament the demise of the old cathode ray tubes (CRT) that have served us so well since the beginning of television. But the form factor and brightness of flat panel technology seems to have all but obsoleted CRTs,
  • despite many experts' belief in the superior picture quality the old tubes produced.

Since the late 1960s, "field emission displays" (FED) have been demonstrated and researched as a possible alternative to CRTs. But many hurdles prevented their development and commercialization, including legal issues over intellectual property and manufacturing challenges. Those issues are finally resolving, and the electronic industry analyst firm iSuppli Corporation predicts an upsurge in the application of flat panels based on FED technology. By the year 2012, iSuppli believes that FED-based displays will be a well-established alternative to plasmas and LCDs with real advantages in specific AV applications, including digital signage, outdoor applications, and professional monitors, among others.

According to a recent report from iSuppli, field emission displays use a vacuum envelope and phosphor-coated glass, similar to a CRT. But instead of illuminating those phosphors with three guns that scan the entire screen, FEDs use hundreds or thousands of "guns" (called "emitters") per pixel. Unlike plasmas and LCDs, FEDs typically use a passive matrix driving method instead of an active matrix, which reduces cost and power consumption. In fact, a FED typically consumes about one-fifth the power of an LED character display or a plasma character display of the same resolution. And FEDs can operate over a temperature range of -35 to 85 degrees C, which his far wider than LCDs (typically -5 to 60 degree C).

Despite these advantages, there remain a few challenges before FEDs go mainstream. They require a high breakdown voltage, and current devices have lifetimes only in the range of 5,000 to 10,000 hours, compared to greater than 50,000 hours for TFT-LCDs. And like other phosphor-based emissive displays, they do suffer from residual image ("burn-in"). Although FEDs have excellent dark-room contrast ratio, the contrast ratio is only about 7:1 in daylight (10,000 lux ambient brightness). The resolution of FED is about 0.3 mm for one RGB pixel, which is better than plasma displays, but it is less than the resolution of LCD.

The main attraction of FEDs is their video performance - wide viewing angle, high luminance, fast response time - as well as the their relatively simple manufacturing process. Unlike other flat panel types, they require no polarizers, color filter, backlights, or thin film transistors, for example.

However, the attempts at mass production of large area, full-color FEDs have not been successful thus far due to difficulties with vacuum packaging and sealing, and the limited lifetimes of some emitter designers. However, analysts at iSuppli expect these challenges to be resolved. By the year 2012, they expect the total market for FEDs to reach 2 million units, with a value of $199 million.

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