Editing Field-emission display (section)

==Operation==
FED display operates like a conventional [[cathode-ray tube]] (CRT) with an [[electron gun]] that uses high voltage (10 kV) to accelerate electrons, which in turn excite the phosphors, but instead of a single electron gun, an FED display contains a grid of individual nanoscopic electron guns. It consists of 2 sheets of glass spaced at regular intervals that face each other, one of which contains the emitters, spacers and the grid, and the other that contains the phosphors.

An FED screen is constructed by laying down a series of metal stripes onto a glass plate to form a series of cathode lines. [[Photolithography]] is used to lay down a series of rows of switching gates at right angles to the cathode lines, forming an addressable grid. At the intersection of each row and column a small patch of  up to 4,500 emitters<ref>{{Cite web|url=https://www.slideshare.net/herishjalel/application-of-carbon-nanotube-in-fed-display|title=Application of carbon nanotube in fed display|date=February 9, 2014}}</ref> is deposited, typically using methods developed from [[inkjet printer]]s. The metal grid is laid on top of the switching gates to complete the gun structure.<ref name=eetimes2007/>

A high voltage-gradient field is created between the emitters and a metal mesh suspended above them, pulling electrons from the tips of the emitters. This is a highly non-linear process, and small changes in voltage will quickly cause the number of emitted electrons to saturate. The grid can be individually addressed, but only the emitters located at the crossing points of the powered cathode, gate lines will have enough power to produce a visible spot, and any power leaks to surrounding elements will not be visible.<ref name=eetimes2007>
Richard Fink, [http://www.eetasia.com/ARTICLES/2007AUG/PDF/EEOL_2007AUG16_OPT_TA.pdf "A closer look at SED, FED technologies"] {{webarchive|url=https://web.archive.org/web/20110616183341/http://www.eetasia.com/ARTICLES/2007AUG/PDF/EEOL_2007AUG16_OPT_TA.pdf |date=2011-06-16 }}, ''EE Tines-Asia'', August 16–31, 2007, pp.&nbsp;1–4.</ref> The non-linearity of the process allows avoidance of [[active matrix addressing]] schemes – once the pixel lights up, it will naturally glow. Non-linearity also means that the brightness of the sub-pixel is [[pulse-width modulation|pulse-width modulated]] to control the number of electrons being produced,<ref name=eetimes2007/> like in [[plasma displays]].

The grid voltage sends the electrons flowing into the open area between the emitters at the back and the screen at the front of the display, where a second accelerating voltage additionally accelerates them towards the screen, giving them enough energy to light the phosphors. Since the electrons from any single emitter are fired toward a single sub-pixel, the scanning electromagnets are not needed.<ref name=eetimes2007/>

CNT-FEDs use carbon nanotubes doped with nitrogen and/or boron as emitters. Samsung has previously worked on the development of this kind of display, however, Samsung has never released any products using this technology. CNT-FED places the carbon nanotube emitters at the bottom center of cavities called gate holes, which are made using electrically insulating material. A gold film is deposited on top of this material without blocking the gate holes in order to allow electrons from the carbon nanotubes to pass through. The gold film acts as a gate or grid, which accelerates the electrons. Gold is also used as the cathode, and the carbon nanotubes are built on top of it. The cathode is laid out using photolithography to create an addressable grid. Spacers are placed at regular intervals which keep both glass panels 300 microns apart. The space created by the spaces contains a vacuum. The anode may be made out of aluminum or [[Indium tin oxide]] (ITO), and it may be placed below or on top of the phosphors.<ref>{{cite AV media |url=https://www.researchgate.net/figure/The-comprehensive-scheme-of-a-CNT-FED-b-CNT-BLU-c-buckypaper-BLU_fig1_257336940 |title=The comprehensive scheme of a CNT-FED, b CNT- BLU, c buckypaper BLU |via=[[ResearchGate]]}}</ref><ref>{{Cite web|url=https://steemit.com/steemstem/@darmawanbuchari/development-of-field-emission-display-fed-based-on-the-idea-of-lightning-rod-49205429faab2|title=Development of Field Emission Display (FED) Based on the Idea of Lightning Rod|first=Darmawanbuchariin Steemstem • 2 Years|last=Ago|date=February 6, 2018|website=Steemit}}</ref><ref>{{Cite web|url=https://www.nanowerk.com/spotlight/spotid=316.php|title=Making Nanotube TVs happen|website=Nanowerk}}</ref><ref>{{Cite web|url=https://www.researchgate.net/figure/CNT-Field-Emission-Display-FED-Monitor-4_fig1_27237144|title=Figure 1.1. CNT-Field Emission Display (FED) Monitor &#91;4&#93;}}</ref><ref>{{Cite web|url=https://slideplayer.com/slide/8625345/|title=First Principles Calculation of the Field Emission of Nitrogen/Boron Doped Carbon Nanotubes Hyo-Shin Ahn §, Seungwu Han †, Kwang-Ryeol Lee, Do Yeon Kim. - ppt download|website=slideplayer.com}}</ref><ref>{{Cite web|url=https://encyclopedia2.thefreedictionary.com/FED|title=FED|via=The Free Dictionary}}</ref><ref name="auto">{{Cite web|url=https://www.engineersgarage.com/article_page/field-emission-display/|title=Field Emission Display|date=July 5, 2019|website=Engineers Garage}}</ref><ref>{{Cite web|url=https://www.cnet.com/news/image-how-field-emission-displays-work/|title=Image: How field emission displays work|website=CNET}}</ref>