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A computer monitor is an output device that displays information in pictorial or text form. A monitor usually comprises a visual display,
some circuitry
some circuitry
, a casing, and a
power supply #REDIRECT Power supply#REDIRECT Power supply A power supply is an electrical device that supplies electric power to an electrical load. The primary function of a power supply is to convert electric current from a source to the correct voltage, el ...

power supply
. The
display device A display device is an output device An output device is any piece of computer hardware Computer hardware includes the physical parts of a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or ...
in modern monitors is typically a
thin film transistor liquid crystal display A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display (LCD) that uses thin-film-transistor (TFT) technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix L ...
(TFT-LCD) with LED backlighting having replaced
cold-cathode fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...
(CCFL) backlighting. Previous monitors used a
cathode ray tube A cathode-ray tube (CRT) is a vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current An electric current is a stream of charged particles, such as electrons ...

cathode ray tube
(CRT) and some
Plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral) or heliotrope, a mineral aggregate * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood plasma ...

Plasma
(also called Gas-Plasma) displays. Monitors are connected to the computer via
VGA Video Graphics Array (VGA) is a video display controller A video display controller or VDC (also regularly called display engine, display interface) is an integrated circuit An integrated circuit or monolithic integrated circuit (also ...

VGA
,
Digital Visual Interface Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working GroupThe Digital Display Working Group (DDWG) was a group whose purpose was to define and maintain the Digital Visual Interface standard. It was ...

Digital Visual Interface
(DVI),
HDMI High-Definition Multimedia Interface (HDMI) is a proprietary hardware, proprietary audio/video Interface (computing), interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant s ...

HDMI
,
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 (), formally known as Video Electronics Standards Association, is an ...

DisplayPort
,
USB-C USB-C (formally known as USB Type-C) is a 24-pin USB Universal Serial Bus (USB) is an industry standard ''Industry Standard'' is a 1982 album by Dixie Dregs, The Dregs. It is their only album featuring vocals (by Alex Ligertwood of Sa ...

USB-C
,
low-voltage differential signaling Low-voltage differential signaling, or LVDS, also known as TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential signaling, differential, serial communication, serial signaling standard, but it is not a ...
(LVDS) or other proprietary connectors and signals. Originally, computer monitors were used for
data processing Data processing is, generally, "the collection Collection or Collections may refer to: * Cash collection, the function of an accounts receivable department * Collection agency, agency to collect cash * Collections management (museum) ** Colle ...

data processing
while
television set A television set or television receiver, more commonly called the television, TV, TV set, tube, telly, or tele, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television Television ...
s were used for entertainment. From the 1980s onwards, computers (and their monitors) have been used for both data processing and entertainment, while
televisions Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in color, and in two or 3D television, three dimensions and sound. The term can refe ...
have implemented some computer functionality. The common
aspect ratio The aspect ratio of a geometric Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are ...
of televisions, and computer monitors, has changed from 4:3 to 16:10, to 16:9. Modern computer monitors are easily interchangeable with conventional television sets and vice versa. However, as computer monitors do not necessarily include integrated
speakers Speaker may refer to: Roles * Speaker (politics), the presiding officer in a legislative assembly * Public speaker, one who gives a speech or lecture * A person producing speech Electronics * Loudspeaker, a device that produces sound ** Computer ...
nor TV tuners (such as
digital television adapter A digital TV converter box A digital television adapter (DTA), commonly known as a converter box or decoder box, is a television tuner that receives a digital television Digital television (DTV) is the transmission of television audiovisual s ...
s), it may not be possible to use a computer monitor as a TV set without external components.


History

Early electronic computers were fitted with a panel 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), but this term had mostly fallen 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 display. A liquid-crystal display (LCD) is a flat panel display, flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. ...
.


Cathode ray tube

The first computer monitors used
cathode ray tube A cathode-ray tube (CRT) is a vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current An electric current is a stream of charged particles, such as electrons ...

cathode ray tube
s (CRTs). Prior to the advent of
home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...

home computer
s in the late 1970s, it was common for a
video display terminal A computer terminal is an electronic or electromechanical In engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and b ...
(VDT) using a CRT to be physically integrated with a keyboard and other components of the system in a single large
chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load Load or LOAD may refer to: Aeronautics and transportation *Load factor (aeronautics), the ratio of the lift of an aircraft to its weight *Passenger load factor, the ratio o ...

chassis
. The display was
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and far less sharp and detailed than on a modern flat-panel 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 the 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 The Tektronix 4010 series was a family of text-and-graphics computer terminal A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer A ...
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 launched in 1977 and sold by through their stores. The name is an abbreviation of ''Tandy Radio Shack, Z80 icroprocessor'. It ...

TRS-80
and
Commodore PET The Commodore PET is a line of personal computer A personal computer (PC) is a multi-purpose computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern comp ...

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 The Apple II (stylized as apple ] '') is an 8-bit home computer">8-bit.html" ;"title="'') is an 8-bit">'') is an 8-bit home computer and one of the world's first highly successful mass-produced microcomputer products. It was designed primari ...

Apple II
computer or
Atari 2600 The Atari 2600, originally branded as the Atari Video Computer System (Atari VCS) until November 1982, is a home video game console A home video game console is a video game console that is designed to be connected to a display device, suc ...

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 The Color Graphics Adapter (CGA), originally also called the ''Color/Graphics Adapter'' or ''IBM Color/Graphics Monitor Adapter'', introduced in 1981, was IBM International Business Machines Corporation (IBM) is an American multinational ...
, 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 The Enhanced Graphics Adapter (EGA) is an IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first computer released in the IBM PC model line and the basis for the IBM PC compatible IBM PC compatible compute ...
which was capable of producing 16 colors and had a resolution of . By the end of the 1980s color CRT monitors that could clearly display pixels were widely available and increasingly affordable. During the following decade, maximum display resolutions gradually increased and prices continued to fall. CRT technology remained dominant in the PC monitor market into the new millennium partly because it was cheaper to produce and offered to view angles close to 180°. CRTs still offer some image quality advantages over 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 A liquid-crystal display (LCD) is a flat-panel display A flat-panel display (FPD) is an electronic display device s, LED display and Vacuum flu ...

TFT-LCD
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 over a period of years 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, who manufactures high-end display products and other solutions for markets such as business, healthcare, graphics, air traffic control, and maritime. The company is headquartered ...
FlexScan L66 in the mid-1990s, the
SGI 1600SW The 1600SW is a widescreen Widescreen images are images that are displayed within a set of aspect ratios The aspect ratio of a geometric Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, w ...
, Apple Studio Display and the
ViewSonic ViewSonic Corporation is a privately-held multinational electronics company with headquarters in Brea, California Brea (; meaning 'oil' or 'tar' in Spanish) is a city in northern Orange County, California. The population as of the 2010 census ...
VP140 in 1998. In 2003, TFT-LCDs outsold CRTs for the first time, becoming the primary technology used for computer monitors. The main advantages of LCDs over CRT displays are that LCDs consume less power, take up much less space, and are considerably lighter. The now common active matrix TFT-LCD technology also has less flickering than CRTs, which reduces eye strain. On the other hand, CRT monitors have superior contrast, have a superior response time, are able to use multiple screen resolutions natively, and there is no discernible flicker if the refresh rate is set to a sufficiently high value. LCD monitors have now very high temporal accuracy and can be used for vision research.
High dynamic range High dynamic range (HDR) is a dynamic range higher than usual. The term is often used in discussing display devices, photography Photography is the art, application, and practice of creating durable images by recording light, either electronic ...
(HDR) has been implemented into high-end LCD monitors to improve color accuracy. Since around the late 2000s, widescreen LCD monitors have become popular, in part due to
television series upright=1.35, A live television show set and cameras A television show – or simply TV show – is any content produced for viewing on a television set A Sony Wega CRT television set A television set or television receiver, more commonly c ...
,
motion pictures A film, also called a movie, motion picture or moving picture, is a work of visual art used to simulate experiences that communicate ideas, stories, perceptions, feelings, beauty, or atmosphere through the use of moving images. These imag ...
and
video game#REDIRECT Video game A video game is an electronic game that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to generate visual f ...
s transitioning to high-definition (HD), which makes standard-width monitors unable to display them correctly as they either stretch or crop HD content. These types of monitors may also display it in the proper width, by filling the extra space at the top and bottom of the image with a solid color (" letterboxing"). Other advantages of widescreen monitors over standard-width monitors is that they make work more productive by displaying more of a user's documents and images, and allow displaying toolbars with documents. They also have a larger viewing area, with a typical widescreen monitor having a 16:9 aspect ratio, compared to the 4:3 aspect ratio of a typical standard-width monitor.


Organic light-emitting diode

Organic light-emitting diode An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode A light-emitting diode (LED) is a semiconductor A semiconductor material has an v ...
(OLED) monitors provide higher contrast, better color reproduction and viewing angles than LCDs but they require more power when displaying documents with white or bright backgrounds and have a severe problem known as burn-in, just like CRTs. They are less common than LCD monitors and are often more expensive.


Measurements of performance

The performance of a monitor is measured by the following parameters: * Display geometry: **
Viewable image size On 2D displays, such as computer monitor A computer monitor is an output device that displays information in pictorial form. A monitor usually comprises the visual display, circuitry, casing, and power supply A power supply is an electri ...
- 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 The aspect ratio of a geometric Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are ...
- 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 In differential geometry Differential geometry is a Mathematics, mathematical discipline that uses the techniques of differential calculus, integral calculus, linear algebra and multilinear algebra to study problems in geometry. The Differentia ...

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 Digital television (DTV) is the transmission of television audiovisual Audiovisual (AV) is electronic media 200px, Graphical representations of electrical audio data. ...
is the number of distinct pixels in each dimension that can be displayed. For a given display size, maximum resolution is limited by dot pitch or DPI. **
Dot pitch Dot pitch (sometimes called line pitch, stripe pitch, or phosphor pitch) is a specification for a computer display, computer printer, image scanner, or other pixel-based devices that describe the distance, for example, between dots (pixel#Subpix ...

Dot pitch
or pixel pitch represents the size of the primary elements of the display. In CRTs, dot pitch is defined as the distance between sub-pixels of the same color. In LCDs it is the distance between the center of two adjacent pixels. Dot pitch is the reciprocal of pixel density. **
Pixel density Pixels per inch (ppi) and pixels per centimetre (ppcm or pixels/cm) are measurements of the pixel density of an electronic image device, such as a computer monitor A computer monitor is an output device that displays information in pictorial or ...
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 Luminance is a photometricPhotometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an ...

Luminance
- measured in candelas per square meter (cd/m, also called a ''nit''). **
Contrast ratio The contrast ratio (CR) is a property of a display system, defined as the ratio In mathematics, a ratio indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the rat ...
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. **
Color depth Color depth or colour depth (see spelling differences Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography ...
- 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 image represented in 1-bit black-and-white space with dithering Dither is an intentionally applied form of image noise, noise used to randomize quantization error Quantization, in mathematics and digital signal processing, is the proces ...
. **
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 circu ...
- measured as coordinates in the
CIE 1931 color space The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum The visible spectrum is the portion of the that is to the . in this range of s is called ' or ...
. The names
sRGB sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft Microsoft Corporation is an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countr ...
or
Adobe RGB The Adobe RGB (1998) color space or opRGB is a color space A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of color -- whe ...
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 excessive degradation to the image. It is measured in degrees horizontally and vertically. *Input speed characteristics: **
Refresh rate The refresh rate (or "vertical refresh rate", "vertical scan rate", terminology originating with the cathode ray tubes) is the number of times per second that a Raster scan, raster-based display device displays a new image. This is independent from ...
is (in CRTs) the number of times in a second that the display is illuminated (the number of times a second a
raster scan A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics upright=1, The Smiley, smiley face in the top left corner is a raster image. Wh ...
is completed). In LCDs it is the number of times the image can be changed per second, expressed in hertz (Hz). Maximum refresh rate is limited by response time. Determines the maximum number of frames per second (FPS) a monitor is capable of showing. ** 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 is the time it takes for a monitor to display an image after receiving it, typically measured in milliseconds (ms). *
Power consumption Electric energy consumption is the form of energy consumption Energy consumption is the amount of energy or power used. Biology In the body, energy consumption is part of energy homeostasis. It derived from food energy. Energy consumption in ...
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 SAR radar image acquired by the SIR-C/X-SAR radar on board the Space Shuttle Endeavour shows the Teide volcano. The city of Santa Cruz de Tenerife is visible as the purple and white area on the lower right edge of the island. Lava flows ...

picture
,
video Video is an electronic Electronic may refer to: *Electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active d ...

video
or working space, without obstruction from the case 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 A prototype is an early sample, mode ...

design
. The main measurements for display devices are: width, height, total area and the diagonal. The size of a display is usually by monitor manufacturers given by the diagonal, i.e. 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 visible area than an eighteen-inch cathode ray tube. The estimation of the monitor size by the distance between opposite corners does not take into account the
display aspect ratio The Aspect ratio (image), aspect ratio of a display device is the proportional relationship between the width and the height of the display. It is expressed as two numbers separated by a colon (''x'':''y''), where ''x'' corresponds to the width an ...
, so that for example a 16:9
widescreen Widescreen images are images that are displayed within a set of aspect ratios The aspect ratio of a geometric Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, with arithmetic Arithmetic ...
display has less
area Area is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value in ...

area
, 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 The aspect ratio of a geometric Geometry (from the grc, γεωμετρία; '' geo-'' "earth", '' -metron'' "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are ...
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
laptop A laptop, laptop computer, or notebook computer is a small, portable personal computer A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are ...

laptop
s and later also in standalone monitors. Reasons for this transition was productive uses for such monitors, i.e. besides widescreen computer game play 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 CAD 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 display. A liquid-crystal display (LCD) is a flat panel display, flat-panel display or other electronically modulated optical device that uses t ...

LCD monitor
s and the same year 16:10 was the mainstream standard for
laptop A laptop, laptop computer, or notebook computer is a small, portable personal computer A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. Personal computers are ...

laptop
s and
notebook computers A laptop or laptop computer is a small, portable personal computer (PC) with a "Flip (form), clamshell" form factor, typically having a thin Liquid-crystal display, LCD or Light-emitting diode, LED computer screen mounted on the inside of the u ...
. 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 providing a substantially higher image resolution Image resolution is the detail an holds. The term applies to s, film images, and other types of images. Higher resolution m ...
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 corporation, multinational manufacturing Conglomerate (company), conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affil ...

Samsung
, 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 early 1980s, to during the late 1990s. Since 2009, the most commonly sold resolution for computer monitors is . Before 2013 top-end consumer LCD monitors were limited to at , excluding Apple products and CRT monitors. Apple introduced with Retina MacBook Pro at on June 12, 2012, and introduced a Retina iMac at on October 16, 2014. By 2015 most major display manufacturers had released resolution displays.


Gamut

Every RGB monitor has its own
color gamut , displayed in the CIE 1931 chromaticity diagram The CIE 1931 color spaces are the first defined quantitative links between distributions of wavelengths in the electromagnetic visible spectrum, and physiologically perceived colors in human color ...
, bounded in
chromaticity Chromaticity is an objective specification of the quality of a color Color (American English) or colour (Commonwealth English) is the visual perception, visual perceptual Physical property, property corresponding in humans to the cate ...
by a
color triangle A color triangle is an arrangement of colors within a triangle, based on the Additive color, additive combination of three primary colors at its corners. An additive color space defined by three primary colors has a chromaticity gamut that i ...
. Some of these triangles are smaller than the
sRGB sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft Microsoft Corporation is an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countr ...
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 A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of color -- whe ...
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 Exchangeable image file format (officially Exif, according to JEIDA/JEITA/CIPA specifications) is a standard that specifies the formats for image An image (from la, imago) is an artifact that depicts visual perception Visual pe ...
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 that 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 adjusted to display it correctly.
Color management In digital imaging systems, color management (or colour management) is the controlled conversion between the color Color ( American English), or colour ( Commonwealth English), is the characteristic of visual perception described throug ...
is needed both in
electronic publishing Electronic publishing (also referred to as publishing, digital publishing, or online publishing) includes the digital publication of e-book An ebook (short for electronic book), also known as an e-book or eBook, is a publication made availabl ...
(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") personal computer, computer. It was first used almost exclusively for print publications, but now it also assists in the creation of variou ...
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 ,
camera A camera is an optical Optics is the branch of physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and t ...

camera
,
microphone A microphone, colloquially called a mic or mike (), is a device – a transducer A transducer is a device that energy from one form to another. Usually a transducer converts a in one form of energy to a signal in another. Transducers ar ...

microphone
, or set of
speakers Speaker may refer to: Roles * Speaker (politics), the presiding officer in a legislative assembly * Public speaker, one who gives a speech or lecture * A person producing speech Electronics * Loudspeaker, a device that produces sound ** Computer ...
. 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 of 21:9 or 32:9 as opposed to the more common 16:9. 32:9 monitors are marketed as super ultrawide monitors. :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 LCD monitors, replace the traditional anti-glare matte finish with a glossy one. This increases
color saturation File:Saturation of digital colors.png, 300x300px, 7.5PB and 10BG Munsell hue pages of RGB colors, showing lines of uniform saturation (chroma in proportion to lightness) in red. Note that lines of uniform saturation radiate from near the black ...
and sharpness but reflections from lights and windows are very visible. Anti-reflective coatings are sometimes applied to help reduce reflections, although this only mitigates the effect. :Curved designs In about 2009,
NEC is a Japanese multinational information technology and electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active d ...
/
Alienware Alienware is an American computer hardware subsidiary of Dell. Their product range is dedicated to gaming computers which can be identified by their alien-themed designs. Alienware was founded in 1996 by Nelson Gonzalez and Alex Aguila. The ...

Alienware
together with Ostendo Technologies, Inc. (based in Carlsbad, CA) were offering a curved (concave) monitor that allows better viewing angles near the edges, covering 75% of
peripheral vision Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the ...

peripheral vision
in the horizontal direction. This monitor had 2880x900 resolution, 4 DLP rear projection systems with LED light sources and was marketed as suitable both for gaming and office work, while for $6499 it was rather expensive. While this particular monitor is no longer in production, most PC manufacturers now offer some sort of curved desktop display. :3D Newer monitors are able to display a different image for each eye, often with the help of special glasses, 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 A graphics tablet (also known as a digitizer, digital graphic tablet, pen tablet, or digital art board) is a computer input device In computing, an input device is a piece of equipment used to provide data and control signals to an information ...
. 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 tilt and rotation as well. Touch and tablet screens are used on LCDs as a 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 In digital imaging systems, color management (or colour management) is the controlled conversion between the color Color ( American English), or colour ( Commonwealth English), is the characteristic of visual perception described throug ...
control for take a near-perfect image. :Local dimming backlit Option for professional LCD monitors, and basic feature of OLED screens; professional feature with mainstream tendency. :Backlit 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.


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
Video Electronics Standards Association VESA (), formally known as Video Electronics Standards Association, is an American technical standards organization for computer display standard Computer display standards are a combination of aspect ratio The aspect ratio of a geometric ...
, VESA, standard mount. Using a VESA standard mount allows the monitor to be used with an after-market stand once 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 InterfaceThe Flat Display Mounting Interface (FDMI), also known as VESA Mounting Interface Standard (MIS) or colloquially as VESA mount, is a family of standards defined by the Video Electronics Standards Association for mounting flat panel computer display, ...
(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 A flat-panel display (FPD) is an electronic display device s, LED display and Vacuum fluorescent display, VF display, top to bottom. A display device is an output device for presentation of information in visual or Touch, tactile form (the latter ...
monitor Monitor or monitor may refer to: Places * Monitor, Alberta * Monitor, Indiana, town in the United States * Monitor, Kentucky * Monitor, Oregon, unincorporated community in the United States * Monitor, Washington * Monitor, Logan County, West Virg ...
s, s, and other 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 equip ...
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 LCD 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 LCDs. 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 LCD is the largest size that will fit within the rails of a 19-inch rack. Larger LCDs 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 LCDs 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. The display is visible only when the display is 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 LCD, 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 LCD will be sealed to the back of the front panel to prevent water and dirt contamination.


Open frame

An open frame monitor provides the LCD monitor and enough supporting structure to hold associated electronics and to minimally support the LCD. Provision will be made for attaching the unit to some external structure for support and protection. Open frame LCDs are intended to be built into some other piece of equipment. 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 LCD manufacturers will purchase desktop displays, take them apart, and discard the outer plastic parts, keeping the inner open-frame LCD 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 *Comparison of CRT, LCD, Plasma, and OLED displays *Flat panel display *Multi-monitor *Vector monitor *Virtual desktop *Variable refresh rate *High frame rate *Head-mounted display


References


External links

{{Basic computer components Computer monitors, American inventions Computer peripherals Display devices