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A computer monitor is an
output device An output device is any piece of computer hardware equipment which converts information into a human-perceptible form or, historically, into a physical machine-readable form for use with other non-computerized equipment. It can be text, graphics, ...
that displays information in pictorial or textual form. A discrete monitor comprises a visual display, support electronics,
power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As ...
,
housing Housing, or more generally, living spaces, refers to the construction and assigned usage of houses or buildings individually or collectively, for the purpose of shelter. Housing ensures that members of society have a place to live, whether ...
, electrical connectors, and external user controls. The display in modern monitors is typically an LCD with
LED backlight A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination ( ambient light or a sp ...
, having by the 2010s replaced CCFL
backlit A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination ( ambient light or a ...
LCDs. Before the mid- 2000s, most monitors used a CRT. Monitors are connected to the computer via
DisplayPort DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). It is primarily used to connect a video source to a display device su ...
,
HDMI High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controlle ...
, USB-C,
DVI Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a comp ...
,
VGA Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the PC industry within three years. The term can now ...
, or other proprietary connectors and signals. Originally, computer monitors were used for data processing while television sets were used for video. From the 1980s onward, computers (and their monitors) have been used for both data processing and video, while televisions have implemented some computer functionality. In the 2000s, the typical display aspect ratio of both televisions and computer monitors has changed from 4:3 to 16:9. Modern computer monitors are mostly interchangeable with television sets and vice versa. As most computer monitors do not include integrated speakers, TV tuners, nor
remote control In electronics, a remote control (also known as a remote or clicker) is an electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operate devices such ...
s, external components such as a DTA box may be needed to use a computer monitor as a TV set.


History

Early electronic computer front panels were fitted with an array of light bulbs where the state of each particular bulb would indicate the on/off state of a particular register bit inside the computer. This allowed the engineers operating the computer to monitor the internal state of the machine, so this panel of lights came to be known as the 'monitor'. As early monitors were only capable of displaying a very limited amount of information and were very transient, they were rarely considered for program output. Instead, a line printer was the primary output device, while the monitor was limited to keeping track of the program's operation. Computer monitors were formerly known as visual display units (VDU), particularly in British English. This term mostly fell out of use by the 1990s.


Technologies

Multiple technologies have been used for computer monitors. Until the 21st century most used cathode-ray tubes but they have largely been superseded by LCD monitors.


Cathode-ray tube

The first computer monitors used cathode-ray tubes (CRTs). Prior to the advent of home computers in the late 1970s, it was common for a video display terminal (VDT) using a CRT to be physically integrated with a keyboard and other components of the workstation in a single large chassis, typically limiting them to emulation of a paper
teletypewriter A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initi ...
, thus the early epithet of 'glass TTY'. The display was monochromatic and far less sharp and detailed than on a modern monitor, necessitating the use of relatively large text and severely limiting the amount of information that could be displayed at one time. High-resolution CRT displays were developed for specialized military, industrial and scientific applications but they were far too costly for general use; wider commercial use became possible after the release of a slow, but affordable Tektronix 4010 terminal in 1972. Some of the earliest home computers (such as the
TRS-80 The TRS-80 Micro Computer System (TRS-80, later renamed the Model I to distinguish it from successors) is a desktop microcomputer launched in 1977 and sold by Tandy Corporation through their Radio Shack stores. The name is an abbreviation of ' ...
and Commodore PET) were limited to monochrome CRT displays, but color display capability was already a possible feature for a few MOS 6500 series-based machines (such as introduced in 1977 Apple II computer or Atari 2600 console), and the color output was a speciality of the more graphically sophisticated Atari 800 computer, introduced in 1979. Either computer could be connected to the antenna terminals of an ordinary color TV set or used with a purpose-made CRT color monitor for optimum resolution and color quality. Lagging several years behind, in 1981 IBM introduced the Color Graphics Adapter, which could display four colors with a resolution of pixels, or it could produce pixels with two colors. In 1984 IBM introduced the Enhanced Graphics Adapter which was capable of producing 16 colors and had a resolution of . By the end of the 1980s color progressive scan CRT monitors were widely available and increasingly affordable, while the sharpest prosumer monitors could clearly display high-definition video, against the backdrop of efforts at
HDTV High-definition television (HD or HDTV) describes a television system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since 1936; in more recent times, it refers to the g ...
standardization from the 1970s to the 1980s failing continuously, leaving consumer
SDTV Standard-definition television (SDTV, SD, often shortened to standard definition) is a television system which uses a resolution that is not considered to be either high or enhanced definition. "Standard" refers to it being the prevailing sp ...
s to stagnate increasingly far behind the capabilities of computer CRT monitors well into the 2000s. During the following decade, maximum display resolutions gradually increased and prices continued to fall as CRT technology remained dominant in the PC monitor market into the new millennium, partly because it remained cheaper to produce. CRTs still offer color, grayscale, motion, and latency advantages over today's LCDs, but improvements to the latter have made them much less obvious. The dynamic range of early LCD panels was very poor, and although text and other motionless graphics were sharper than on a CRT, an LCD characteristic known as pixel lag caused moving graphics to appear noticeably smeared and blurry.


Liquid-crystal display

There are multiple technologies that have been used to implement liquid-crystal displays (LCD). Throughout the 1990s, the primary use of LCD technology as computer monitors was in laptops where the lower power consumption, lighter weight, and smaller physical size of LCDs justified the higher price versus a CRT. Commonly, the same laptop would be offered with an assortment of display options at increasing price points: (active or passive) monochrome, passive color, or active matrix color (TFT). As volume and manufacturing capability have improved, the monochrome and passive color technologies were dropped from most product lines.
TFT-LCD A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in cont ...
is a variant of LCD which is now the dominant technology used for computer monitors. The first standalone LCDs appeared in the mid-1990s selling for high prices. As prices declined they became more popular, and by 1997 were competing with CRT monitors. Among the first desktop LCD computer monitors was the
Eizo is a Japanese visual technology company, founded in March 1968, which manufactures display products and other solutions for markets such as business, healthcare, graphics, air traffic control, and maritime. The company is headquartered in Ha ...
FlexScan L66 in the mid-1990s, the SGI 1600SW, Apple Studio Display and the ViewSonic VP140 in 1998. In 2003, LCDs outsold CRTs for the first time, becoming the primary technology used for computer monitors. The physical advantages of LCD over CRT monitors are that LCDs are lighter, smaller, and consume less power. In terms of performance, LCDs produce less or no flicker, reducing eyestrain, sharper image at native resolution, and better checkerboard contrast. On the other hand, CRT monitors have superior blacks, viewing angles, response time, are able to use arbitrary lower resolutions without aliasing, and flicker can be reduced with higher refresh rates, though this flicker can also be used to reduce motion blur compared to less flickery displays such as most LCDs. Many specialized fields such as vision science remain dependent on CRTs, the best LCD monitors having achieved moderate temporal accuracy, and so can be used only if their poor spatial accuracy is unimportant.
High dynamic range High dynamic range (HDR) is a dynamic range higher than usual, synonyms are wide dynamic range, extended dynamic range, expanded dynamic range. The term is often used in discussing the dynamic range of various signals such as images, videos, au ...
(HDR) has been implemented into high-end LCD monitors to improve grayscale accuracy. Since around the late 2000s, widescreen LCD monitors have become popular, in part due to television series, motion pictures and
video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This feedba ...
s transitioning to widescreen, which makes squarer monitors unsuited to display them correctly.


Organic light-emitting diode

Organic light-emitting diode (OLED) monitors provide most of the benefits of both LCD and CRT monitors with few of their drawbacks, though much like plasma panels or very early CRTs they suffer from burn-in, and remain very expensive.


Measurements of performance

The performance of a monitor is measured by the following parameters: * Display geometry: ** Viewable image size - is usually measured diagonally, but the actual widths and heights are more informative since they are not affected by the aspect ratio in the same way. For CRTs, the viewable size is typically smaller than the tube itself. ** Aspect ratio - is the ratio of the horizontal length to the vertical length. Monitors usually have the aspect ratio 4:3, 5:4, 16:10 or 16:9. ** Radius of curvature (for curved monitors) - is the radius that a circle would have if it had the same curvature as the display. This value is typically given in millimeters, but expressed with the letter "R" instead of a unit (for example, a display with "3800R curvature" has a 3800mm radius of curvature. *
Display resolution The display resolution or display modes of a digital television, computer monitor or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution ...
is the number of distinct pixels in each dimension that can be displayed natively. For a given display size, maximum resolution is limited by dot pitch or DPI. ** Dot pitch represents the distance between the primary elements of the display, typically averaged across it in nonuniform displays. A related unit is pixel pitch, In LCDs, pixel pitch is the distance between the center of two adjacent pixels. In CRTs, pixel pitch is defined as the distance between subpixels of the same color. Dot pitch is the reciprocal of pixel density. ** Pixel density is a measure of how densely packed the pixels on a display are. In LCDs, pixel density is the number of pixels in one linear unit along the display, typically measured in pixels per inch (px/in or ppi). *Color characteristics: ** Luminance - measured in candelas per square meter (cd/m, also called a ''nit''). ** Contrast ratio is the ratio of the luminosity of the brightest color (white) to that of the darkest color (black) that the monitor is capable of producing simultaneously. For example, a ratio of means that the brightest shade (white) is 20,000 times brighter than its darkest shade (black). Dynamic contrast ratio is measured with the LCD backlight turned off. ANSI contrast is with both black and white simultaneously adjacent onscreen. ** Color depth - measured in bits per primary color or bits for all colors. Those with 10bpc (bits per channel) or more can display more shades of color (approximately 1 billion shades) than traditional 8bpc monitors (approximately 16.8 million shades or colors), and can do so more precisely without having to resort to dithering. **
Gamut In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circ ...
- measured as coordinates in the CIE 1931 color space. The names sRGB or
Adobe RGB The Adobe RGB (1998) color space or opRGB is a color space developed by Adobe Systems, Inc. in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as a comp ...
are shorthand notations. ** Color accuracy - measured in ΔE (delta-E); the lower the ΔE, the more accurate the color representation. A ΔE of below 1 is imperceptible to the human eye. A ΔE of 24 is considered good and requires a sensitive eye to spot the difference. ** Viewing angle is the maximum angle at which images on the monitor can be viewed, without subjectively excessive degradation to the image. It is measured in degrees horizontally and vertically. *Input speed characteristics: ** Refresh rate is (in CRTs) the number of times in a second that the display is illuminated (the number of times a second a raster scan is completed). In LCDs it is the number of times the image can be changed per second, expressed in hertz (Hz). Determines the maximum number of frames per second (FPS) a monitor is capable of showing. Maximum refresh rate is limited by response time. ** Response time is the time a pixel in a monitor takes to change between two shades. The particular shades depend on the test procedure, which differs between manufacturers. In general, lower numbers mean faster transitions and therefore fewer visible image artifacts such as ghosting. Grey to grey (GtG), measured in milliseconds (ms). **
Input latency Input lag or input latency is the amount of time that passes between sending an electrical signal and the occurrence of a corresponding action. In video games the term is often used to describe any latency between an input and either the game o ...
is the time it takes for a monitor to display an image after receiving it, typically measured in milliseconds (ms). * Power consumption is measured in watts.


Size

On two-dimensional display devices such as computer monitors the display size or view able image size is the actual amount of screen space that is available to display a
picture An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimension ...
,
video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) sy ...
or working space, without obstruction from the bezel or other aspects of the unit's
design A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process or the result of that plan or specification in the form of a prototype, product, or process. The verb ''to design' ...
. The main measurements for display devices are: width, height, total area and the diagonal. The size of a display is usually given by manufacturers diagonally, i.e. as the distance between two opposite screen corners. This method of measurement is inherited from the method used for the first generation of CRT television, when picture tubes with circular faces were in common use. Being circular, it was the external diameter of the glass envelope that described their size. Since these circular tubes were used to display rectangular images, the diagonal measurement of the rectangular image was smaller than the diameter of the tube's face (due to the thickness of the glass). This method continued even when cathode-ray tubes were manufactured as rounded rectangles; it had the advantage of being a single number specifying the size, and was not confusing when the aspect ratio was universally 4:3. With the introduction of flat panel technology, the diagonal measurement became the actual diagonal of the visible display. This meant that an eighteen-inch LCD had a larger viewable area than an eighteen-inch cathode-ray tube. Estimation of monitor size by the distance between opposite corners does not take into account the display aspect ratio, so that for example a 16:9 widescreen display has less
area Area is the quantity that expresses the extent of a region on the plane or on a curved surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an op ...
, than a 4:3 screen. The 4:3 screen has dimensions of and area , while the widescreen is , .


Aspect ratio

Until about 2003, most computer monitors had a 4:3 aspect ratio and some had 5:4. Between 2003 and 2006, monitors with 16:9 and mostly 16:10 (8:5) aspect ratios became commonly available, first in laptops and later also in standalone monitors. Reasons for this transition included productive uses for such monitors, i.e. besides
Field of view in video games In first person video games, the field of view or field of vision (abbreviated FOV) is the extent of the observable game world that is seen on the display at any given moment. It is typically measured as an angle, although whether this angle is ...
and movie viewing, are the word processor display of two standard letter pages side by side, as well as CAD displays of large-size drawings and application menus at the same time. In 2008 16:10 became the most common sold aspect ratio for
LCD monitor A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in cont ...
s and the same year 16:10 was the mainstream standard for laptops and
notebook computers A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
. In 2010, the computer industry started to move over from 16:10 to 16:9 because 16:9 was chosen to be the standard
high-definition television High-definition television (HD or HDTV) describes a television system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since 1936; in more recent times, it refers to the g ...
display size, and because they were cheaper to manufacture. In 2011, non-widescreen displays with 4:3 aspect ratios were only being manufactured in small quantities. According to
Samsung The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...
, this was because the "Demand for the old 'Square monitors' has decreased rapidly over the last couple of years," and "I predict that by the end of 2011, production on all 4:3 or similar panels will be halted due to a lack of demand."Widescreen monitors: Where did 1920×1200 go?
Mybroadband.co.za (2011-01-10). Retrieved on 2011-12-24.


Resolution

The resolution for computer monitors has increased over time. From during the late 1970s, to during the late 1990s. Since 2009, the most commonly sold resolution for computer monitors is , shared with the
1080p 1080p (1920×1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen ve ...
of HDTV. Before 2013 mass market LCD monitors were limited to at , excluding niche professional monitors. By 2015 most major display manufacturers had released ( 4K UHD) displays, and the first ( 8K) monitors had begun shipping.


Gamut

Every RGB monitor has its own color gamut, bounded in chromaticity by a color triangle. Some of these triangles are smaller than the sRGB triangle, some are larger. Colors are typically encoded by 8 bits per primary color. The RGB value 55, 0, 0represents red, but slightly different colors in different color spaces such as
Adobe RGB The Adobe RGB (1998) color space or opRGB is a color space developed by Adobe Systems, Inc. in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as a comp ...
and sRGB. Displaying sRGB-encoded data on wide-gamut devices can give an unrealistic result. The gamut is a property of the monitor; the image color space can be forwarded as Exif metadata in the picture. As long as the monitor gamut is wider than the color space gamut, correct display is possible, if the monitor is calibrated. A picture which uses colors that are outside the sRGB color space will display on an sRGB color space monitor with limitations. Still today, many monitors that can display the sRGB color space are not factory nor user calibrated to display it correctly. Color management is needed both in electronic publishing (via the Internet for display in browsers) and in
desktop publishing Desktop publishing (DTP) is the creation of documents using page layout software on a personal ("desktop") computer. It was first used almost exclusively for print publications, but now it also assists in the creation of various forms of online ...
targeted to print.


Additional features


Universal features

:Power saving Most modern monitors will switch to a power-saving mode if no video-input signal is received. This allows modern operating systems to turn off a monitor after a specified period of inactivity. This also extends the monitor's service life. Some monitors will also switch themselves off after a time period on standby. Most modern laptops provide a method of screen dimming after periods of inactivity or when the battery is in use. This extends battery life and reduces wear. :Indicator light Most modern monitors have two different indicator light colors wherein if video-input signal was detected, the indicator light is green and when the monitor is in power-saving mode, the screen is black and the indicator light is orange. Some monitors have different indicator light colors and some monitors have blinking indicator light when in power-saving mode. :Integrated accessories Many monitors have other accessories (or connections for them) integrated. This places standard ports within easy reach and eliminates the need for another separate hub,
camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with ...
,
microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...
, or set of speakers. These monitors have advanced microprocessors which contain codec information, Windows interface drivers and other small software which help in proper functioning of these functions. :Ultrawide screens Monitors that feature an aspect ratio greater than 2:1 (for instance, 21:9 or 32:9, as opposed to the more common 16:9, which resolves to 1.7:1).Monitors with an aspect ratio greater than 3:1 are marketed as super ultrawide monitors. These are typically massive curved screens intended to replace a multi-monitor deployment. :Touch screen These monitors use touching of the screen as an input method. Items can be selected or moved with a finger, and finger gestures may be used to convey commands. The screen will need frequent cleaning due to image degradation from fingerprints.


Consumer features

:Glossy screen Some displays, especially newer flat panel monitors, replace the traditional anti-glare matte finish with a glossy one. This increases color saturation and sharpness but reflections from lights and windows are more visible. Anti-reflective coatings are sometimes applied to help reduce reflections, although this only partly mitigates the problem. :Curved designs Most often using nominally flat-panel display technology such as LCD or OLED, a concave rather than convex curve is imparted, reducing geometric distortion, especially in extremely large and wide seamless desktop monitors intended for close viewing range. :3D Newer monitors are able to display a different image for each eye, often with the help of special glasses and polarizers, giving the perception of depth. An autostereoscopic screen can generate 3D images without headgear.


Professional features

:Anti-glare and anti-reflection screens Features for medical using or for outdoor placement. :Directional screen Narrow viewing angle screens are used in some security-conscious applications. :Integrated professional accessories Integrated screen calibration tools, screen hoods, signal transmitters; Protective screens. :Tablet screens A combination of a monitor with a graphics tablet. Such devices are typically unresponsive to touch without the use of one or more special tools' pressure. Newer models however are now able to detect touch from any pressure and often have the ability to detect tool tilt and rotation as well. Touch and tablet sensors are often used on
sample and hold In electronics, a sample and hold (also known as sample and follow) circuit is an analog device that samples (captures, takes) the voltage of a continuously varying analog signal and holds (locks, freezes) its value at a constant level for a ...
displays such as LCDs to substitute for the light pen, which can only work on CRTs. :Integrated display LUT and 3D LUT tables The option for using the display as a reference monitor; these calibration features can give an advanced color management control for take a near-perfect image. :Local dimming backlight Option for professional LCD monitors, inherent to OLED & CRT; professional feature with mainstream tendency. :Backlight brightness/color uniformity compensation Near to mainstream professional feature; advanced hardware driver for backlit modules with local zones of uniformity correction.


Mounting

Computer monitors are provided with a variety of methods for mounting them depending on the application and environment.


Raw monitor

Raw monitors are raw framed LCD monitors, to install a monitor on a not so common place, ie, on the car door or you need it in the trunk. It is usually paired with a power adapter to have a versatile monitor for home or commercial use.


Desktop

A desktop monitor is typically provided with a stand from the manufacturer which lifts the monitor up to a more ergonomic viewing height. The stand may be attached to the monitor using a proprietary method or may use, or be adaptable to, a VESA mount. A VESA standard mount allows the monitor to be used with more after-market stands if the original stand is removed. Stands may be fixed or offer a variety of features such as height adjustment, horizontal swivel, and landscape or portrait screen orientation.


VESA mount

The Flat Display Mounting Interface (FDMI), also known as VESA Mounting Interface Standard (MIS) or colloquially as a VESA mount, is a family of standards defined by the Video Electronics Standards Association for mounting flat panel displays to stands or wall mounts. It is implemented on most modern flat-panel monitors and TVs. For computer monitors, the VESA Mount typically consists of four threaded holes on the rear of the display that will mate with an adapter bracket.


Rack mount

Rack mount A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is wide. The 19 inch dimension includes the edges or "ears" that protrude from each side of the equ ...
computer monitors are available in two styles and are intended to be mounted into a 19-inch rack: ;Fixed A fixed rack mount monitor is mounted directly to the rack with the flat-panel or CRT visible at all times. The height of the unit is measured in rack units (RU) and 8U or 9U are most common to fit 17-inch or 19-inch screens. The front sides of the unit are provided with flanges to mount to the rack, providing appropriately spaced holes or slots for the rack mounting screws. A 19-inch diagonal screen is the largest size that will fit within the rails of a 19-inch rack. Larger flat-panels may be accommodated but are 'mount-on-rack' and extend forward of the rack. There are smaller display units, typically used in broadcast environments, which fit multiple smaller screens side by side into one rack mount. ;Stowable A stowable rack mount monitor is 1U, 2U or 3U high and is mounted on rack slides allowing the display to be folded down and the unit slid into the rack for storage as a drawer. The flat display is visible only when pulled out of the rack and deployed. These units may include only a display or may be equipped with a keyboard creating a KVM (Keyboard Video Monitor). Most common are systems with a single LCD but there are systems providing two or three displays in a single rack mount system.


Panel mount

A panel mount computer monitor is intended for mounting into a flat surface with the front of the display unit protruding just slightly. They may also be mounted to the rear of the panel. A flange is provided around the screen, sides, top and bottom, to allow mounting. This contrasts with a rack mount display where the flanges are only on the sides. The flanges will be provided with holes for thru-bolts or may have studs welded to the rear surface to secure the unit in the hole in the panel. Often a gasket is provided to provide a water-tight seal to the panel and the front of the screen will be sealed to the back of the front panel to prevent water and dirt contamination.


Open frame

An open frame monitor provides the display and enough supporting structure to hold associated electronics and to minimally support the display. Provision will be made for attaching the unit to some external structure for support and protection. Open frame monitors are intended to be built into some other piece of equipment providing its own case. An arcade video game would be a good example with the display mounted inside the cabinet. There is usually an open frame display inside all end-use displays with the end-use display simply providing an attractive protective enclosure. Some rack mount monitor manufacturers will purchase desktop displays, take them apart, and discard the outer plastic parts, keeping the inner open-frame display for inclusion into their product.


Security vulnerabilities

According to an NSA document leaked to Der Spiegel, the NSA sometimes swaps the monitor cables on targeted computers with a bugged monitor cable in order to allow the NSA to remotely see what is being displayed on the targeted computer monitor. Van Eck phreaking is the process of remotely displaying the contents of a CRT or LCD by detecting its electromagnetic emissions. It is named after Dutch computer researcher Wim van Eck, who in 1985 published the first paper on it, including proof of concept. Phreaking more generally is the process of exploiting telephone networks.Definition of terms clarified and discussed in Aaron Schwabach, ''Internet and the Law: Technology, Society, and Compromises, 2nd Edition'' (Santa Barbara CA: ABC-CLIO, 2014), 192-3.


See also

*
History of display technology 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 v ...
* Comparison of CRT, LCD, plasma, and OLED displays *
Flat panel display 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. Flat-panel displays are thin, lightweight, provide better l ...
* Head-mounted display *
High frame rate In motion picture technology—either film or video—high frame rate (HFR) refers to higher frame rates than typical prior practice. The frame rate for motion picture film cameras was typically 24 frames per second (fps) with multiple flashes ...
* Liquid-crystal display * Multi-monitor * Vector monitor * Virtual desktop * Variable refresh rate


References


External links

{{Basic computer components American inventions Computer peripherals Display devices