A display is an output device that is used to display the data on the screen that is given through some medium. The electronic display has multiple applications such as computer monitors, television, mobile, tablet and etc. Displays can be characterized as
1- two-dimensional 2- three-dimensional.
1- two-dimensional displays
1.1 Cathode ray tube display (CRT)
A cathode-ray tube is used to display images on the screen when an electron beam strikes a phosphorescent surface of the screen. Most of the displays use CRTs. like television receivers, and computer displays.
It is consist of a vacuum tube, one or more electron guns, a phosphorescent display, deflecting coils, and an anode. The electron gun is used to generate an electron beam then the anode is used to accelerate the electrons. Now to display the image on screen low-frequency deflecting coils are used to control the electron beam. There are two different types of deflecting coils: vertical and horizontal. The intensity of the electron beam can be changed. When these electrons strike a phosphor-coated screen they produce a tiny bright spot.
1.2 Light-emitting diode display (LED)
LED stands for Light-emitting diode, it type of diode that emits light when current flows through it. When electrons of this semiconductor recombine with holes, releasing energy in the form of energy packets called photons. The color of the emitted light depends upon on energy of the electron to cross the band gap of the semiconductor. In LED Displays the white LEDs are situated around the edge of the screen and a diffusion panel is used to illuminate the white light on the screen evenly.
LED Display is a display technology that uses a panel of LEDs to produce images on the screen. Most electronic devices, both large and small use LED display technology such as mobile phones, tablets, computers, laptops, TVs, etc.
1.3 Electroluminescent display (ELD)
Electroluminescent technology works as when electrons and holes recombine in semiconductors then as a result the excited electrons release energy in the form of photons. Electroluminescent Displays are created by sandwiching a layer of electroluminescent material between two layers of conductors. When current flows through these layers of material radiation emits in the form of visible light. Electroluminescent devices are very similar to capacitors in many ways, but the difference between them is the phosphors layer used in electroluminescent displays. The type of display is used in automobile dashboard audio devices and electronic gadgets such as calculators wrist watches and etc.
1.4 Electronic paper, E Ink display
Electronic paper or E Ink displays are referred to as “reflective displays.” In LCD technology a backlight is projected through the display and then it reaches our eyes. In an E-Ink display technology rather than using a backlight the light of the environment is used as a source, it reflects on the surface of the display and then back to our eyes. So E Ink display does not look dim in bright light but it looks brighter and clear. It is more reliable and better than LCD for a long period of time.
1.5 Liquid crystal display (LCD)
LCD stands for Liquid crystal display, This display technology uses liquid crystals for the main operation. The transparent electrodes are stick to each side of the liquid crystal and then the glass layer. LCD displays are much thinner than cathode ray tubes (CRT). The power consumption of LCD technology is less than gas-display and LED. As LCDs have replaced older technologies, the new technology OLEDs have replaced LCDs.
1.6 High-Performance Addressing display (HPA)
High-performance addressing (HPA) is another display technology that is used in different computer monitors and TV screens. It was first developed by Sharp and Hitachi to use low-end portable computers and laptops. It uses passive-matrix technology to display images on a screen.
1.7 Thin-film transistor display (TFT)
Thin-film transistors are field-effect transistors that are primarily used in liquid crystal displays (LCD). This TFT technology has features of controlling each individual pixel. Each Thin-film transistor act as a single switch that allows the pixel to change its state rapidly, which helps to turn it on and off much more quickly. The TFTs are arranged in a matrix called “active-matrix” TFTs.
1.8 Organic light-emitting diode display (OLED)
An organic light-emitting diode is another type of diode that is known as an organic electroluminescent diode. The organic tin film is sandwiched between two conductive diodes. When an external voltage is applied the charge carriers move into organic thin films and recombine and forming excitons. Then at deexcitation, it loses and gains energy in the form of visible light, like red, blue, or green. OLEDs are used in most electronic devices such as television screens, computers, mobile phones, and handled gaming consoles and etc.
1.9 AMOLED display
AMOLED stands for active-matrix organic light-emitting diode and it is also a type of OLED display technology. The AMOLED display is made of pixels deposited into a thin film transistor. OLED is the same as LED but OLED technology it is using organic compounds as an emissive electroluminescent layer.AMOLED display technology has been used since 2007 in TVs, media players, mobile phones, digital cameras, and different kinds of monitors as well. Since then it continue moving toward low-cost, low-power, large size, and high resolution.
1.10 Vacuum Fluorescent display
A VFD stands for Vacuum Fluorescent display. It works on the same principle as the cathode ray tube, but it works on very low power. VFD is more clear in color contrast and is bright than LCD. A vacuum fluorescent display (VFD) is a display commonly used in electronic devices such as microwave ovens, video cassette recorders and etc.
1.11 Digital Light Processing display (DLP)
DLP stands for Digital Light Processing this technology use micromirrors to reflect light onto the screen. These mirrors are positioned in chips and they are very small in size. These micromirror pitch measure less than 5.5μm. A single mirror projects one or more pixels of the image. The number of mirrors depends on the resolution of the projected image. The motion of mirrors allowed to creation of colors and gray shades that form video. DLP technology is also used in 3-D printing.
1.12 Surface-conduction electron-emitter display (SED) (experimental)
A SED stands for surface-conduction electron-emitter, this technology is a flat panel display developed by Canon and Toshiba Corporation. The SED technology uses nanoscopic-size of electron emitters to energize colored phosphors and an image. SED consists of a matrix of small cathode ray tubes, a single tube contains sub-pixel such as red-green-blue(RGB)pixels. SED contains the features of CRTs monitors like wide viewing angle, high contrast ratios, and fast response times, and thin like LCD displays and they also use less power than LCD displays.
1.13 Field emission display (FED) (experimental)
FED stands for Field emission display this is used in flat monitors, it uses the large surface area as a source that emits electrons that strike the colored phosphor which produces an image on the screen. Sony was a major supporter of the FED display during the 2000s and planned to produce mass production in 2009 but after the evolution of LCD, the FED was missing away. Because LCD was better in any expect than FED.
1.14 Laser TV (forthcoming)
laser TV forthcoming display technology that uses two or more modulated optical laser rays of different colors that produce a combined spot that is projected on the image plane by a polygon-mirror system to produce a color television display. The system works either scanning the whole image or a single dot at a time, much like the electron beams in CRT.
1.15 Quantum dot display (QLED)
A QLED stands for Quantum dot LED, this type of display uses quantum dots technology the nanocrystal semiconductor that produces pure monochromatic light of red, green, and blue colors. the quantum dots are excited when the blue light of the display panel falls on it to produce pure primary colors. The light travels through QD layer film made of color pigments. The QD technology is primarily used in LCDs and LED. This technology is applicable in other displays which use color filters such as MicroLED, UV AMOLED, and QNED panels.
1.16 Interferometric modulator display (IMOD)
IMOD stands for Interferometric modulator display, this technology is used in electronic displays that produce various colors due to interference of reflected light. The color is selected with an electric modulator that is switched on and off using driver-integrated circuits similar to those to address liquid crystal displays (LCD). Interferometric modulator display flat panel display consists of thousands of individual IMOD elements.
1.17 Digital micro shutter display (DMS)
DMS stands for Digital micro shutter display, this technology works on low power and provides exceptional image quality. It also supports E-paper compatible modes. Its extraordinary image quality is due to its mechanism and optical architecture. DMS is based on the micro-shutter form on the TFT backplane, this technology has feature color sequential and division gray scale, and it uses 1/4 power consumption compared to LCD, TFT, and OLED.
1.18 microLED (in development)
mLED stands for micro-LED, mLED, or µLED, this technology is based on tiny micro-LED devices that are used to directly create colors. Micro-LED displays produce great-looking and efficient displays that even challenge today’s high-end level OLED displays. mLED was first developed in 2000 by the research group of Hongxing Jiang of Texas Tech University. MicroLED displays consist of arrays of microscopic LEDs that perform as a single pixel.
2- Three-dimensional displays
2.1 Swept-volume display
This type of technology is used to display 3D video. A volumetric display is used to represent an object in three physical dimensions. A true volumetric display creates a great and real three-dimensional object, even there is no real object are present. The unreal object has the same properties as an actual material object that appears to seem real.
2.2 Laser display
Laser light display is mostly involved in audience entertainment reasons. Laser display is a term used to describe the application of laser light for different entertainment purposes. Laser light shows consist of a projected laser that is set to music, typically it is used for musical performances. The coherent nature of laser light allows producing drawing patterns or images on different surfaces like walls, ceilings and etc.
2.3 Holographic display
Holography is a technique in which we recorded wavefront and afterward re-constructed it. Holography is the most known method for three-dimensional image generation, but this is also used in many other applications. A holographic display is a type of three-dimensional display that uses light diffraction to produce an image. The holographic display is different from the rest 3D displays, the viewer does not need to wear any special equipment or glasses to see the effects.
2.4 Light field displays
The light field is a vector function that means the total amount of light flowing in every direction through every point in space. Light field display technology is used the copy image light and reproduces the reflected light to produce and visual effect, the effect is natural-looking without any special equipment like 3D glasses.