Computer monitor

  (Redirected from Computer display)

A computer monitor is an output device that displays information in pictorial or text form. A monitor usually comprises a visual display, some circuitry, a casing, and a power supply. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) with LED backlighting having replaced cold-cathode fluorescent lamp (CCFL) backlighting. Previous monitors used a cathode ray tube (CRT) and some Plasma (also called Gas-Plasma) displays. Monitors are connected to the computer via VGA, Digital Visual Interface (DVI), HDMI, DisplayPort, USB-C, low-voltage differential signaling (LVDS) or other proprietary connectors and signals.

A liquid crystal display (LCD) computer monitor
A cathode-ray tube (CRT) computer monitor


Modern computer monitors are easily interchangeable with conventional television sets and vice versa. However, as computer monitors do not necessarily include integrated speakers nor TV tuners (such as digital television adapters), it may not be possible to use a computer monitor as a TV set without external components.[1][2]






Cathode ray tubeEdit

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 system in a single large chassis. The display was monochromatic 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 terminal in 1972.

Some of the earliest home computers (such as the TRS-80 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 320 × 200 pixels, or it could produce 640 × 200 pixels with two colors. In 1984 IBM introduced the Enhanced Graphics Adapter which was capable of producing 16 colors and had a resolution of 640 × 350.[4]


Liquid crystal displayEdit


TFT-LCD is a variant of LCD which is now the dominant technology used for computer monitors.[6]

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 FlexScan L66 in the mid-1990s, the SGI 1600SW, Apple Studio Display and the ViewSonic VP140[7] in 1998. In 2003, TFT-LCDs outsold CRTs for the first time, becoming the primary technology used for computer monitors.[5] 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.[8] 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[9] is set to a sufficiently high value. LCD monitors have now very high temporal accuracy and can be used for vision research.[10]


Organic light-emitting diodeEdit


Measurements of performanceEdit

The performance of a monitor is measured by the following parameters:

  • Display geometry:
    • 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 3800 mm radius of curvature.[11]
    • 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 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/m2, 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 20,000∶1 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 - measured in bits per primary color or bits for all colors. Those with 10 bpc (bits per channel) or more can display more shades of color (approximately 1 billion shades) than traditional 8 bpc monitors (approximately 16.8 million shades or colors), and can do so more precisely without having to resort to dithering.
    • Gamut - measured as coordinates in the CIE 1931 color space. The names sRGB or Adobe RGB 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 2–4 is considered good and requires a sensitive eye to spot the difference.
  • 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). 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.
    • Input latency 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.







Aspect ratioEdit


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 display size, and because they were cheaper to manufacture.[citation needed]

In 2011, non-widescreen displays with 4:3 aspect ratios were only being manufactured in small quantities. According to 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."[15]


The resolution for computer monitors has increased over time. From 320 × 200 during the early 1980s, to 1024 × 768 during the late 1990s. Since 2009, the most commonly sold resolution for computer monitors is 1920 × 1080.[16] Before 2013 top-end consumer LCD monitors were limited to 2560 × 1600 at 30 in (76 cm), excluding Apple products and CRT monitors. Apple introduced 2880 × 1800 with Retina MacBook Pro at 15.4 in (39 cm) on June 12, 2012, and introduced a 5120 × 2880 Retina iMac at 27 in (69 cm) on October 16, 2014. By 2015 most major display manufacturers had released 3840 × 2160 resolution displays.


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 [255, 0, 0] represents red, but slightly different colors in different color spaces such as Adobe RGB and sRGB. Displaying sRGB-encoded data on wide-gamut devices can give an unrealistic result.[17] 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 that uses colors that are outside the sRGB color space will display on an sRGB color space monitor with limitations.[18] Still today, many monitors that can display the sRGB color space are not factory adjusted to display it correctly. Color management is needed both in electronic publishing (via the Internet for display in browsers) and in desktop publishing targeted to print.

Additional featuresEdit

Universal featuresEdit

LG monitors: consumer-grade (left) and professional-oriented (with screen hood and integrated calibration tool)
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.


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


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


Consumer featuresEdit

Glossy screen


Curved designs

In about 2009, NEC/Alienware together with Ostendo Technologies, Inc. (based in Carlsbad, CA) were offering a curved (concave) 43-inch (110 cm) monitor that allows better viewing angles near the edges, covering 75% of 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.[19] While this particular monitor is no longer in production, most PC manufacturers now offer some sort of curved desktop display.


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 featuresEdit

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.

Eizo ColorEdge monitor with screen hood
Integrated professional accessories

Integrated screen calibration tools, screen hoods, signal transmitters; Protective screens.

Tablet screens



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 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.





VESA mountEdit

Hydraulic arm monitor stand, connected via VESA mount holes

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 monitors, TVs, and other displays to stands or wall mounts.[20] It is implemented on most modern flat-panel monitors and TVs.


Rack mountEdit







Panel mountEdit


Open frameEdit


Security vulnerabilitiesEdit

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.[21]

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.[22]

See alsoEdit


  1. ^ "Difference Between TV and Computer Monitor | Difference Between". Retrieved 2018-01-15.
  2. ^ "Difference Between laptop and Computer Monitor | Difference Between". Retrieved 2021-04-27.
  3. ^ "How Computers Work: Input and Output". Retrieved 2020-05-29.
  4. ^ "Cathode Ray Tube (CRT) Monitors". Archived from the original on 2011-03-26. Retrieved 2011-05-20.
  5. ^ a b "CRT Monitors". PCTechGuide.Com. Archived from the original on 2011-05-23. Retrieved 2011-05-20.
  6. ^ "TFT Central". TFT Central. 2017-09-29. Archived from the original on 2017-06-29. Retrieved 2017-09-29.
  7. ^ "Boot Magazine 1998 – LCD Monitor Review". April 2012.
  8. ^ "Is the LCD monitor right for you?". Archived from the original on 2010-12-27. Retrieved 2011-05-20.
  9. ^ a b "Refresh rate: A note-worthy factor for a PC monitor". Review Rooster. 26 September 2018.
  10. ^ Wang, P. and D. Nikolić (2011) An LCD monitor with sufficiently precise timing for research in vision. Frontiers in Human Neuroscience, 5:85. Wang, Peng; Nikolić, D. (2011). "An LCD monitor with sufficiently precise timing for research in vision". Frontiers in Human Neuroscience. 5: 85. doi:10.3389/fnhum.2011.00085. PMC 3157744. PMID 21887142.
  11. ^ "Deep Dive into Curved Displays".
  12. ^ NEMATech Computer Display Standards "Archived copy". Archived from the original on 2012-03-02. Retrieved 2011-04-29.CS1 maint: archived copy as title (link)
  14. ^ "Product Planners and Marketers Must Act Before 16:9 Panels Replace Mainstream 16:10 and Monitor LCD Panels, New DisplaySearch Topical Report Advises". DisplaySearch. 2008-07-01. Archived from the original on 2011-07-21. Retrieved 2011-05-20.
  15. ^ Widescreen monitors: Where did 1920×1200 go? Archived 2011-01-13 at the Wayback Machine (2011-01-10). Retrieved on 2011-12-24.
  16. ^ Monitors/TFT 16:9/16:10 | Skinflint Price Comparison EU Archived 2012-04-26 at the Wayback Machine. Retrieved on 2011-12-24.
  17. ^ Friedl, Jeffrey. "Digital-Image Color Spaces, Page 2: Test Images". Retrieved 2018-12-10. See For Yourself The Effects of Misinterpreted Color Data
  18. ^ Koren, Norman. "Gamut mapping". Archived from the original on 2011-12-21. Retrieved 2018-12-10. The rendering intent determines how colors are handled that are present in the source but out of gamut in the destination
  19. ^ R. Nelson (2009) Archived 2013-04-14 at the Wayback Machine. NEC/Alienware Curved Display Now Available
  20. ^ "FDMI Overview" (PDF). Archived (PDF) from the original on 2011-09-27.
  21. ^ Shopping for Spy Gear: Catalog Advertises NSA Toolbox, dec 2013 Archived 2015-09-06 at the Wayback Machine
  22. ^ 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. ISBN 9781610693509

External linksEdit