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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.
There are various technologies used for electronic visual displays:
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.
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) |
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.
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 |
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 [1] | |
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 | |
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)).| | |
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). |
A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not emit light directly but instead use a backlight or reflector to produce images in color or monochrome.
Photonics is a branch of optics that involves the application of generation, detection, and manipulation of light in the form of photons through emission, transmission, modulation, signal processing, switching, amplification, and sensing. Photonics is closely related to quantum electronics, where quantum electronics deals with the theoretical part of it while photonics deal with its engineering applications. Though covering all light's technical applications over the whole spectrum, most photonic applications are in the range of visible and near-infrared light. The term photonics developed as an outgrowth of the first practical semiconductor light emitters invented in the early 1960s and optical fibers developed in the 1970s.
A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment.
Display may refer to:
An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector. To display images, LCD projectors typically send light from a metal-halide lamp through a prism or series of dichroic filters that separates light to three polysilicon panels – one each for the red, green and blue components of the video signal. As polarized light passes through the panels, individual pixels can be opened to allow light to pass or closed to block the light. The combination of open and closed pixels can produce a wide range of colors and shades in the projected image.
In color reproduction and colorimetry, a gamut, or color gamut, is a convex set containing the colors that can be accurately represented, i.e. reproduced by an output device or measured by an input device. Devices with a larger gamut can represent more colors. Similarly, gamut may also refer to the colors within a defined color space, which is not linked to a specific device. A trichromatic gamut is often visualized as a color triangle. A less common usage defines gamut as the subset of colors contained within an image, scene or video.
A display device is an output device for presentation of information in visual or tactile form. When the input information that is supplied has an electrical signal the display is called an electronic display.
Liquid crystal on silicon is a miniaturized reflective active-matrix liquid-crystal display or "microdisplay" using a liquid crystal layer on top of a silicon backplane. It is also known as a spatial light modulator. LCoS initially was developed for projection televisions, but has since found additional uses in wavelength selective switching, structured illumination, near-eye displays and optical pulse shaping.
A video projector is an image projector that receives a video signal and projects the corresponding image onto a projection screen using a lens system. Video projectors use a very bright ultra-high-performance lamp, Xenon arc lamp, metal halide lamp, LED or solid state blue, RB, RGB or fiber-optic lasers to provide the illumination required to project the image. Most modern projectors can correct any curves, blurriness and other inconsistencies through manual settings.
Digital light processing (DLP) is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device. It was originally developed in 1987 by Larry Hornbeck of Texas Instruments. While the DLP imaging device was invented by Texas Instruments, the first DLP-based projector was introduced by Digital Projection Ltd in 1997. Digital Projection and Texas Instruments were both awarded Emmy Awards in 1998 for the DLP projector technology. DLP is used in a variety of display applications from traditional static displays to interactive displays and also non-traditional embedded applications including medical, security, and industrial uses.
A television set or television receiver is an electronic device for viewing and hearing television broadcasts, or as a computer monitor. It combines a tuner, display, and loudspeakers. Introduced in the late 1920s in mechanical form, television sets became a popular consumer product after World War II in electronic form, using cathode-ray tube (CRT) technology. The addition of color to broadcast television after 1953 further increased the popularity of television sets in the 1960s, and an outdoor antenna became a common feature of suburban homes. The ubiquitous television set became the display device for the first recorded media for consumer use in the 1970s, such as Betamax, VHS; these were later succeeded by DVD. It has been used as a display device since the first generation of home computers and dedicated video game consoles in the 1980s. By the early 2010s, flat-panel television incorporating liquid-crystal display (LCD) technology, especially LED-backlit LCD technology, largely replaced CRT and other display technologies. Modern flat-panel TVs are typically capable of high-definition display and can also play content from a USB device. In the late 2010s, most flat-panel TVs began offering 4K and 8K resolutions.
An electronic component is any basic discrete electronic device or physical entity part of an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not to be confused with electrical elements, which are conceptual abstractions representing idealized electronic components and elements. A datasheet for an electronic component is a technical document that provides detailed information about the component's specifications, characteristics, and performance. Discrete circuits are made of individual electronic components that only perform one function each as packaged, which are known as discrete components, although strictly the term discrete component refers to such a component with semiconductor material such as individual transistors.
Laser color television, or laser color video display, is a type of television that utilizes two or more individually modulated optical (laser) rays of different colors to produce a combined spot that is scanned and projected across the image plane by a polygon-mirror system or less effectively by optoelectronic means to produce a color-television display. The systems work either by scanning the entire picture a dot at a time and modulating the laser directly at high frequency, much like the electron beams in a cathode ray tube, or by optically spreading and then modulating the laser and scanning a line at a time, the line itself being modulated in much the same way as with digital light processing (DLP).
Large-screen television technology developed rapidly in the late 1990s and 2000s. Prior to the development of thin-screen technologies, rear-projection television was standard for larger displays, and jumbotron, a non-projection video display technology, was used at stadiums and concerts. Various thin-screen technologies are being developed, but only liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been publicly released. Recent technologies like organic light-emitting diode (OLED) as well as not-yet-released technologies like surface-conduction electron-emitter display (SED) or field-emission display (FED) are in development to supersede earlier flat-screen technologies in picture quality.
Digital newspaper technology is the technology used to create or distribute a digital newspaper.
Electrically operated display devices have developed from electromechanical systems for display of text, up to all-electronic devices capable of full-motion 3D color graphic displays. Electromagnetic devices, using a solenoid coil to control a visible flag or flap, were the earliest type, and were used for text displays such as stock market prices and arrival/departure display times. The cathode ray tube was the workhorse of text and video display technology for several decades until being displaced by plasma, liquid crystal (LCD), and solid-state devices such as thin-film transistors (TFTs), LEDs and OLEDs. With the advent of metal–oxide–semiconductor field-effect transistors (MOSFETs), integrated circuit (IC) chips, microprocessors, and microelectronic devices, many more individual picture elements ("pixels") could be incorporated into one display device, allowing graphic displays and video.
A text display is an electronic alphanumeric display device that is mainly or only capable of showing text, or extremely limited graphic characters. This includes electromechanical split-flap displays, vane displays, and flip-disc displays; all-electronic liquid-crystal displays, incandescent eggcrate displays, LED displays, and vacuum fluorescent displays; and even electric nixie tubes.
Polarizing organic photovoltaics (ZOPV) is a concept for harvesting energy from Liquid crystal display screens, developed by engineers from UCLA. This concept enables devices to use external light and the LCD screen's backlight using photovoltaic polarizers. Photovoltaic polarizers convert this light into electricity which can be used to power the device. This concept also provides multifunctional capability to devices with LCD screens as they act as photovoltaic devices and as polarisers.
A see-through display or transparent display is an electronic display that allows the user to see what is shown on the screen while still being able to see through it. The main applications of this type of display are in head-up displays, augmented reality systems, digital signage, and general large-scale spatial light modulation. They should be distinguished from image-combination systems which achieve visually similar effects by optically combining multiple images in the field of view. Transparent displays embed the active matrix of the display in the field of view, which generally allows them to be more compact than combination-based systems.
Laser-powered phosphor display (LPD) is a large-format display technology similar to the cathode-ray tube (CRT). Prysm, Inc., a video wall designer and manufacturer in Silicon Valley, California, invented and patented the LPD technology. The key components of the LPD technology are its TD2 tiles, its image processor, and its backing frame that supports LPD tile arrays. The company unveiled the LPD in January 2010.