Electronic visual display
Encyclopedia
An electronic visual display is display technology which incorporates flat panel display
s, performs as a video display, output device
for presentation of images transmitted electronically, for visual reception, without producing a permanent record.
Common applications for electronic visual displays used to be television set
s or computer monitors, but these days electronic visual displays tend to be ubiquitous as interface for large amounts of visual information in mobile computing
applications like portable information communication technology devices. They can also be found in digital signage
.
A different kind of projection display is the class of "laser projection displays
" where the image is build 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
.
Flat panel display
Flat panel displays encompass a growing number of electronic visual display technologies. They are far lighter and thinner than traditional television sets and video displays that use cathode ray tubes , and are usually less than thick...
s, performs as a video display, output device
Output device
An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system to the outside world....
for presentation of images transmitted electronically, for visual reception, without producing a permanent record.
Common applications for electronic visual displays used to be television set
Television set
A television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...
s or computer monitors, but these days electronic visual displays tend to be ubiquitous as interface for large amounts of visual information in mobile computing
Mobile computing
Mobile computing is a form of human–computer interaction by which a computer is expected to be transported during normal usage. Mobile computing has three aspects: mobile communication, mobile hardware, and mobile software...
applications like portable information communication technology devices. They can also be found in digital signage
Digital signage
Digital signage is a form of electronic display that shows television programming, menus, information, advertising and other messages. Digital signs can be found in public and private environments, such as retail stores, hotels, restaurants and corporate buildings.Digital signage Displays are most...
.
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 | |
| Effect | Liquid crystal display Liquid crystal display A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly.... (LCD) + backlight (this combination is considered an active display) |
LCD |
| Example | LCD TV screen, LCD computer monitor | LCD watch (reflective) see LCD classification |
| Effect | Cathodoluminescence Cathodoluminescence Cathodoluminescence is an optical and electrical phenomenon whereby a beam of electrons is generated by an electron gun and then impacts on a luminescent material such as a phosphor, causing the material to emit visible light. The most common example is the screen of a television... |
Electrophoresis Electrophoresis Electrophoresis, also called cataphoresis, is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. This electrokinetic phenomenon was observed for the first time in 1807 by Reuss , who noticed that the application of a constant electric... also see Electronic paper Electronic paper Electronic paper, e-paper and electronic ink are a range of display technology which are designed to mimic the appearance of ordinary ink on paper. Unlike conventional backlit flat panel displays, electronic paper displays reflect light like ordinary paper... |
| Example | Cathode ray tube Cathode ray tube The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and... (CRT) Field emission display Field emission display A field emission display is a display technology that incorporates flat panel display technology that uses large-area field electron emission sources to provide electrons that strike colored phosphor to produce a color image as a electronic visual display... (FED) Vacuum fluorescent display Vacuum fluorescent display A vacuum fluorescent display is a display device used commonly on consumer-electronics equipment such as video cassette recorders, car radios, and microwave ovens. Invented in Japan in 1967, the displays became common on calculators and other consumer electronics devices... (VFD) Surface-conduction electron-emitter display Surface-conduction Electron-emitter Display A surface-conduction electron-emitter display is a display technology which is currently developing various flat panel displays by a number of companies as a electronic visual displays. SEDs use nanoscopic-scale electron emitters to energize colored phosphors and produce an image... (SED) |
Research & manufacturing: E Ink electronic paper displays SiPix Microcup Electronic Paper |
| Effect | Electroluminescence Electroluminescence Electroluminescence is an optical phenomenon and electrical phenomenon in which a material emits light in response to the passage of an electric current or to a strong electric field... |
Electrochromism Electrochromism Electrochromism is the phenomenon displayed by some materials of reversibly changing color when a burst of charge is applied. Various types of materials and structures can be used to construct electrochromic devices, depending on the specific applications.... |
| Example | (thin or thick film) electro-luminescence (EL) (inorganic or organic) light emitting diode (LED, OLED) gas discharge display (Nixie tube Nixie tube A nixie tube is an electronic device for displaying numerals or other information. The glass tube contains a wire-mesh anode and multiple cathodes. In most tubes, the cathodes are shaped like numerals. Applying power to one cathode surrounds it with an orange glow discharge... ) |
Research & manufacturing: ntera NanoChromics Technology |
| Effect | Photoluminescence Photoluminescence Photoluminescence is a process in which a substance absorbs photons and then re-radiates photons. Quantum mechanically, this can be described as an excitation to a higher energy state and then a return to a lower energy state accompanied by the emission of a photon... |
Electrowetting Electrowetting Electrowetting is the modification of the wetting properties of a surface with an applied electric field.-History:... |
| Example | Plasma display Plasma display A plasma display panel is a type of flat panel display common to large TV displays or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent... panel (PDP) |
Research & manufacturing: Liquavista |
| Effect | Incandescence Incandescence Incandescence is the emission of light from a hot body as a result of its temperature. The term derives from the Latin verb incandescere, to glow white.... |
Electromechanical modulation |
| Example | Numitron, a 7-segment numerical display tube Numitron website | flap display Split-flap display A split-flap display, sometimes simply flap display, is a display device that presents alphanumeric text, and possibly fixed graphics, often used as a public transport timetable in some airports or railway stations, often called Solari boards, named after display manufacturer Solari di... flip-disk display Flip-disc display The flip-disc display is an electromechanical dot matrix display technology used for large outdoor signs, normally those that will be exposed to direct sunlight. Flip-disc technology has been used on buses across North America and Europe. It has also been used extensively on public information... digital micromirror device Digital micromirror device A digital micromirror device, or DMD, is an optical semiconductor that is the core of DLP projection technology, and was invented by Dr. Larry Hornbeck and Dr. William E. "Ed" Nelson of Texas Instruments in 1987.... (DMD) Interferometric modulator display Interferometric modulator display Interferometric modulator display is a technology used in electronic visual displays that can create various colors via interference of reflected light... (IMOD) FTIR (unipixel) telescopic pixel display |
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 Video projector A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other... |
| 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 Head-mounted display A head-mounted display or helmet mounted display, both abbreviated HMD, is a display device, worn on the head or as part of a helmet, that has a small display optic in front of one or each eye .- Overview :... |
A different kind of projection display is the class of "laser projection displays
Laser projectors
A laser projector is a collection of lasers, mirrors, a galvanometer scanners and other optical components housed in an enclosure. A laser projector can contain one laser light source for single color projection or possibly three sources for RGB full color projection.-Laser Diodes :* Red:...
" where the image is build 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
Acousto-optic modulator
An acousto-optic modulator , also called a Bragg cell, uses the acousto-optic effect to diffract and shift the frequency of light using sound waves . They are used in lasers for Q-switching, telecommunications for signal modulation, and in spectroscopy for frequency control. A piezoelectric...
.
Layout of picture elements
Depending on the shape and on the arrangement of the picture elements of a display either fixed information ca 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 Seven-segment display A seven-segment display , or seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot-matrix displays... Fourteen-segment display Fourteen-segment display A fourteen-segment display is a type of display based on 14 segments that can be turned on or off to produce letters and numerals. It is an expansion of the more common seven-segment display, having an additional four diagonal and two vertical segments with the middle horizontal segment... 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 Additive color An additive color model involves light emitted directly from a source or illuminant of some sort. The additive reproduction process usually uses red, green and blue light to produce the other colors. Combining one of these additive primary colors with another in equal amounts produces the... primary color Primary color Primary colors are sets of colors that can be combined to make a useful range of colors. For human applications, three primary colors are usually used, since human color vision is trichromatic.... s add up to produce white light |
subtractive mixing Subtractive color A subtractive color model explains the mixing of paints, dyes, inks, and natural colorants to create a full range of colors, each caused by subtracting some wavelengths of light and reflecting the others... 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 Halftone Halftone is the reprographic technique that simulates continuous tone imagery through the use of dots, varying either in size, in shape or in spacing... (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 Pixel geometry The components of the pixels in an image sensor or display can be ordered in different patterns, called pixel geometry.... see sub-pixel arrangements 2 see sub-pixel arrangements 3 Subpixel rendering Subpixel rendering is a way to increase the apparent resolution of a computer's liquid crystal display or Organic Light Emitting Diode display by rendering pixels to take into account the screen type's physical properties... |
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 devices 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 Passive matrix addressing Passive matrix addressing is an addressing scheme used in earlier LCD displays, and may be used in future LCD displays. This is a matrix addressing scheme meaning that only m + n control signals are required to address a m × n display... 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 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 Liquid crystal on silicon Liquid crystal on silicon is a "micro-projection" or "micro-display" technology typically applied in projection televisions. It is a reflective technology similar to DLP projectors; however, it uses liquid crystals instead of individual mirrors. By way of comparison, LCD projectors use... (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 electrical current (e.g. LED). |
Literature
- ISO 13406-2
- Pochi Yeh, Claire Gu: "Optics of Liquid Crystal Displays", John Wiley & Sons 1999, 4.5. Conoscopy, pp. 139