What’s a FED Display?

FED is short for Field Emission Display

A field-emission display is a type of flat panel display that uses field-emitting cathodes to bombard phosphor coatings, with the latter being the light-emissive medium. Field-emission displays are actually very similar to cathode ray tubes – also known as traditional CRT technology.

However, FEDs are only a few millimeters thick. Instead of a single electron gun, a FED uses a large array of fine metal tips or carbon nanotubes (the most efficient electron emitters known), with many positioned behind each phosphor dot, to emit electrons through a process known as field emission. Because of emitter redundancy, FEDs do not display dead pixels like LCDs even if 20% of the emitters fail. Sony is researching FED because it is the flat-panel technology that comes closest to matching the picture of a CRT.

High-Definition Carbon Nanotube TVs

The new TV screens are a nano version of the field emission displays (FEDs) developed by Motorola and others during the 1990s. Although that technology produced dazzling prototype displays, it cost too much to compete with liquid crystal displays (LCDs). “It didn’t make sense to build a factory [for conventional FEDs]. The cost [of LCDs] was halving each year,” says Kenneth Dean, who leads development for carbon nanotube displays at Motorola. However, he says, carbon nanotubes have given field emission technology a second wind by yielding cheaper components that can be manufactured more easily.

Like LCDs, FEDs are energy efficient and could provide a flat panel technology that features less power consumption than existing LCD and plasma display technologies. They can also be cheaper to make, as they have fewer total components. As of yet, however, there are no consumer production models available in the United States, although small demo panels have been produced.

A field emission display (FED) is a low power, flat cathode ray tube type display that uses a matrix-addressed cold cathode to produce light from a screen coated with phosphor materials. The principle of the field emission display is similar to that of the traditional cathode ray tube display. Field emission displays, like cathode ray tubes, display a color image by emitting light of a predetermined color through the bombardment of electrons onto a field emitter array (FEA) coated with phosphor. They both emit electrons to hit the fluorescent medium on a substrate in vacuum.

Electron emission includes field electron emission, secondary electron emission, and photoelectric emission, as well as thermionic emission. A cold cathode is the cathode that performs electron emission by field electron emission, which occurs due to a tunnel effect when a strong electric field is applied to the vicinity of the surface of a substance to lower the potential barrier on the surface. The cathode ray tube display emits electron beams by a single electron gun and controls the direction of the electron beams by using a polarization plate. Instead, the field emission display is composed of hundreds of thousands of active cold emitters, each of which corresponds to a pixel independently, so no polarization plate is needed.

Field emission displays apply a strong electric field from a gate to a field emitter disposed on a cathode layer at regular intervals, thereby emitting electrons from the field emitter, colliding the electrons with a phosphor material of an anode layer, and emitting light The cold cathode electron source is broadly divided into a field emission electron source and a hot electron type electron source. The former includes a spindt type electron source, a surface conduction type electron source and a carbon nanotube type electron source. The latter includes an MIM (metal-insulator-metal) type electron source stacked with metal-insulator-metal and an MIS (metal-insulator-semiconductor) type electron source stacked with metal-insulator-semiconductor.

When displaying an image in the field emission display, a driving method called a line sequential scanning scheme is used standardly. Display in each of the frames is performed for each scan line (horizontally). All the cold cathode electron sources corresponding to the number of data lines on the same scan line are operated at the same time.