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An electronic visual display is a display device that can display images, video, or text that is transmitted electronically. Electronic visual displays include television sets, computer monitors, and digital signage. They are ubiquitous in mobile computing applications like tablet computers, smartphones, and information appliances. Many electronic visual displays are informally referred to as touch screens.
Starting in the early 2000s, flat-panel displays began to dominate the industry, as cathode-ray tubes (CRT) were phased out, especially for computer applications. Starting in the mid 2010s, curved display panels began to be used in televisions, computer monitors, and smartphones.
Types
There are various technologies used for electronic visual displays:
- Electroluminescent (EL) display
- Liquid crystal display (LCD) with light-emitting diode (LED)-backlit Liquid crystal display (LCD)
- Light-emitting diode (LED) display
- OLED display
- AMOLED display
- Plasma (P) display
- Quantum dot (QD) display
An overhead projector can be considered a type of electronic visual display.
Additionally, CRTs were widely used in the past and microLED displays are under development.
Classification
Electronic visual displays present visual information according to the electrical input signal (analog or digital) either by emitting light (then they are called active displays) or, alternatively, by modulating available light during the process of reflection or transmission (light modulators are called passive displays).
| Electronic visual displays | ||
| Active displays | Passive displays | |
|---|---|---|
| present visual information by emitting light | present visual information by modulating light | |
| Principle | Liquid crystal display (LCD) + backlight (this combination is considered an active display) | LCD |
| Example | LCD TV screen, LCD computer monitor | LCD watch (reflective) see LCD classification |
| Principle | Cathodoluminescence | Electrophoresis also see Electronic paper |
| Example | Cathode ray tube (CRT) Field emission display (FED) Vacuum fluorescent display (VFD) Surface-conduction electron-emitter display (SED) | Research & manufacturing: |
| Principle | Electroluminescence | Electrochromism |
| Example | (thin or thick film) electro-luminescence (EL) (inorganic or organic) light emitting diode (LED, OLED) gas discharge display (Nixie tube) | Research & manufacturing: |
| Principle | Photoluminescence | Electrowetting |
| Example | Plasma display panel (PDP) | Research & manufacturing: |
| Principle | Incandescence | Electromechanical modulation |
| Example | Numitron, a 7-segment numerical display tube | flap display flip-disk display digital micromirror device (DMD) Interferometric modulator display (IMOD) FTIR (unipixel) |
Display mode of observation
Electronic visual displays can be observed directly (direct view display) or the displayed information can be projected to a screen (transmissive or reflective screen). This usually happens with smaller displays at a certain magnification.
| Display modes of observation | |
|---|---|
| Direct view display | Projection display |
| transmissive mode of operation | front-projection (with reflective screen) e.g. video projector |
| reflective mode of operation | rear-projection (with transmissive screen) e.g. rear projection television screen |
| transflective mode of operation (e.g. transflective LCD) | retinal projection (with or without combiner) e.g. head mounted display |
A different kind of projection display is the class of "laser projection displays", where the image is built up sequentially either via line by line scanning or by writing one complete column at a time. For that purpose one beam is formed from three lasers operating at the primary colors, and this beam is scanned electro-mechanically (galvanometer scanner, micro-mirror array)) or electro-acousto-optically.
Layout of picture elements
Depending on the shape and on the arrangement of the picture elements of a display, either fixed information can be displayed (symbols, signs), simple numerals (7-segment layout) or arbitrary shapes can be formed (dot-matrix displays).
| Layout of picture elements | |
|---|---|
| Segmented displays characters, numbers and symbols of fixed shape (may be multiplex addressed) The following layouts are well known: Seven-segment display Fourteen-segment display Sixteen-segment display | Dot-matrix displays sub-pixels are arranged in a regular 2-dimensional array (multiplex addressing required); arbitrary shapes can be formed and displayed |
Emission and control of colors
Colors can be generated by selective emission, by selective absorption, transmission or by selective reflection.
| Color emission and control | |
|---|---|
| additive mixing primary colors add up to produce white light | subtractive mixing filters, dyes, pigments (e.g.printing) subtract (absorb) parts of white light |
| temporal mixing (additive) e.g. rotating primary color filter wheel in projectors | spatial mixing (additive) closely spaced sub-pixels |
| spatio temporal color mixing combined spatial and temporal mixing | |
| arrangement of sub-pixels for additive color mixing see sub-pixel arrangements 1 see sub-pixel arrangements 2 see sub-pixel arrangements 3 | subtractive color mixing does not require special sub-pixel arrangements all components (e.g. filters) have to be in the same path of light. |
| Examples: stripe delta-nabla PenTile arrangement, e.g. RGB+White | |
Addressing modes
Each sub-pixel of a display device must be selected (addressed) in order to be energized in a controlled way.
| Addressing modes (selection of picture elements) | |
|---|---|
| direct addressing each individual picture element has electrical connections to the driving electronics. | multiplexed addressing several picture elements have common electrical connections to the driving electronics, e. g.. row and column electrodes when the picture elements are arranged in a two dimensional matrix. |
| active matrix addressing active electronic elements added in order to improve selection of picture elements.
| passive matrix addressing the nonlinearity of the display effect (e.g. LCD, LED)is used to realize the addressing of individual pixels in multiplex addressing. In this mode only a quite limited number of lines can be addressed. In the case of (STN-)LCDs this maximum is at ~240, but at the expense of a considerable reduction of contrast. |
| The matrix of active electronic elements can be used in transmissive mode of operation (high transmittance required) or a non-transparent active matrix can be used for reflective LCDs (e.g. liquid crystal on silicon (LCOS)).| | |
Display driving modes
| Driving modes (activation of picture elements) | |
|---|---|
| voltage driving activation of pixels by voltage (e.g. LCD field effects). If the current is low enough this mode may be the basis for displays with very low power requirements (e.g. μW for LCDs without backlight). | current driving activation of pixels by electric current (e.g. LED). |
See also
- Display device
- ISO 13406-2
References
- Louis D. Silverstein, et al., Hybrid spatial-temporal color synthesis and its applications, JSID 14/1(2006), pp. 3–13
- SID - Society for Information Display International Conference Proceedings 1970–2008
- Journal of the Society for Information Display (JSID)
- Display Reparatur (in German)
- Passive Displays
- Choosing an IT device
Further reading
- Pochi Yeh, Claire Gu: "Optics of Liquid Crystal Displays", John Wiley & Sons 1999, 4.5. Conoscopy, pp. 139
This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these messages This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Electronic visual display news newspapers books scholar JSTOR April 2023 Learn how and when to remove this message This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations April 2023 Learn how and when to remove this message Learn how and when to remove this message An electronic visual display is a display device that can display images video or text that is transmitted electronically Electronic visual displays include television sets computer monitors and digital signage They are ubiquitous in mobile computing applications like tablet computers smartphones and information appliances Many electronic visual displays are informally referred to as touch screens Starting in the early 2000s flat panel displays began to dominate the industry as cathode ray tubes CRT were phased out especially for computer applications Starting in the mid 2010s curved display panels began to be used in televisions computer monitors and smartphones TypesThere are various technologies used for electronic visual displays Electroluminescent EL display Liquid crystal display LCD with light emitting diode LED backlit Liquid crystal display LCD Light emitting diode LED display OLED display AMOLED display Plasma P display Quantum dot QD display An overhead projector can be considered a type of electronic visual display Additionally CRTs were widely used in the past and microLED displays are under development ClassificationElectronic visual displays present visual information according to the electrical input signal analog or digital either by emitting light then they are called active displays or alternatively by modulating available light during the process of reflection or transmission light modulators are called passive displays Electronic visual displaysActive displays Passive displayspresent visual information by emitting light present visual information by modulating lightPrinciple Liquid crystal display LCD backlight this combination is considered an active display LCDExample LCD TV screen LCD computer monitor LCD watch reflective see LCD classificationPrinciple Cathodoluminescence Electrophoresis also see Electronic paperExample Cathode ray tube CRT Field emission display FED Vacuum fluorescent display VFD Surface conduction electron emitter display SED Research amp manufacturing Principle Electroluminescence ElectrochromismExample thin or thick film electro luminescence EL inorganic or organic light emitting diode LED OLED gas discharge display Nixie tube Research amp manufacturing Principle Photoluminescence ElectrowettingExample Plasma display panel PDP Research amp manufacturing Principle Incandescence Electromechanical modulationExample Numitron a 7 segment numerical display tube flap display flip disk display digital micromirror device DMD Interferometric modulator display IMOD FTIR unipixel Display mode of observationElectronic visual displays can be observed directly direct view display or the displayed information can be projected to a screen transmissive or reflective screen This usually happens with smaller displays at a certain magnification Display modes of observationDirect view display Projection displaytransmissive mode of operation front projection with reflective screen e g video projectorreflective mode of operation rear projection with transmissive screen e g rear projection television screentransflective mode of operation e g transflective LCD retinal projection with or without combiner e g head mounted display A different kind of projection display is the class of laser projection displays where the image is built up sequentially either via line by line scanning or by writing one complete column at a time For that purpose one beam is formed from three lasers operating at the primary colors and this beam is scanned electro mechanically galvanometer scanner micro mirror array or electro acousto optically Layout of picture elementsDepending on the shape and on the arrangement of the picture elements of a display either fixed information can be displayed symbols signs simple numerals 7 segment layout or arbitrary shapes can be formed dot matrix displays Layout of picture elementsSegmented displays characters numbers and symbols of fixed shape may be multiplex addressed The following layouts are well known Seven segment display Fourteen segment display Sixteen segment display Dot matrix displays sub pixels are arranged in a regular 2 dimensional array multiplex addressing required arbitrary shapes can be formed and displayedEmission and control of colorsColors can be generated by selective emission by selective absorption transmission or by selective reflection Color emission and controladditive mixing primary colors add up to produce white light subtractive mixing filters dyes pigments e g printing subtract absorb parts of white lighttemporal mixing additive e g rotating primary color filter wheel in projectors spatial mixing additive closely spaced sub pixelsspatio temporal color mixing combined spatial and temporal mixingarrangement of sub pixels for additive color mixing see sub pixel arrangements 1 see sub pixel arrangements 2 see sub pixel arrangements 3 subtractive color mixing does not require special sub pixel arrangements all components e g filters have to be in the same path of light Examples stripe delta nabla PenTile arrangement e g RGB WhiteAddressing modesEach sub pixel of a display device must be selected addressed in order to be energized in a controlled way Addressing modes selection of picture elements direct addressing each individual picture element has electrical connections to the driving electronics multiplexed addressing several picture elements have common electrical connections to the driving electronics e g row and column electrodes when the picture elements are arranged in a two dimensional matrix active matrix addressing active electronic elements added in order to improve selection of picture elements thin film diodes TFDs thin film transistors TFTs amorphous silicon a Si polycrystalline silicon p Si monocrystalline silicon passive matrix addressing the nonlinearity of the display effect e g LCD LED is used to realize the addressing of individual pixels in multiplex addressing In this mode only a quite limited number of lines can be addressed In the case of STN LCDs this maximum is at 240 but at the expense of a considerable reduction of contrast The matrix of active electronic elements can be used in transmissive mode of operation high transmittance required or a non transparent active matrix can be used for reflective LCDs e g liquid crystal on silicon LCOS Display driving modesDriving modes activation of picture elements voltage driving activation of pixels by voltage e g LCD field effects If the current is low enough this mode may be the basis for displays with very low power requirements e g mW for LCDs without backlight current driving activation of pixels by electric current e g LED See alsoDisplay device ISO 13406 2ReferencesLouis D Silverstein et al Hybrid spatial temporal color synthesis and its applications JSID 14 1 2006 pp 3 13 SID Society for Information Display International Conference Proceedings 1970 2008 Journal of the Society for Information Display JSID Display Reparatur in German Passive Displays Choosing an IT deviceFurther readingPochi Yeh Claire Gu Optics of Liquid Crystal Displays John Wiley amp Sons 1999 4 5 Conoscopy pp 139
