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Encyclopedia > Computer display

A computer display monitor, usually called simply a monitor, is a piece of electrical equipment which displays viewable images generated by a computer without producing a permanent record. The word "monitor" is used in other contexts; in particular in television broadcasting, where a television picture is displayed to a high standard. A computer display device is usually either a cathode ray tube or some form of flat panel such as a TFT LCD. The monitor comprises the display device, circuitry to generate a picture from electronic signals sent by the computer, and an enclosure or case. Within the computer, either as an integral part or a plugged-in interface, there is circuitry to convert internal data to a format compatible with a monitor. A piece of electrical equipment is a machine, powered by electricity and usually consists of an enclosure, a variety of electrical components and often a power switch. ... It has been suggested that this article or section be merged into image (disambiguation). ... This article is about the machine. ... Broadcasting is the distribution of audio and video signals (programs) to a number of recipients (listeners or viewers) that belong to a large group. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... A 15 TFT-LCD TFT-LCD (thin film transistor liquid crystal display) is a variant of liquid crystal display (LCD) which uses thin film transistor (TFT) technology to improve image quality. ... An electronic circuit is an electrical circuit that also contains active electronic devices such as transistors or vacuum tubes. ... This article is about the engineering discipline. ... In the fields of communications, signal processing, and in electrical engineering more generally, a signal is any time-varying quantity. ... An electrical enclosure is a cabinet for electrical equipment to protect the contents from the environment, mount switches, knobs and displays and to prevent electrical shock. ... Look up interface in Wiktionary, the free dictionary. ... In Computer Science, data is often distinguished from code, though both are represented in modern computers as binary strings. ...

Contents

Cathode ray tube

CRT Computer display pixel array(right)
CRT Computer display pixel array(right)

The CRT or cathode ray tube, is the picture tube of a monitor. The back of the tube has a negatively charged cathode. The electron gun shoots electrons down the tube and onto a charged screen. The screen is coated with a pattern of dots that glow when struck by the electron stream. Each cluster of three dots, one of each color, is one pixel. Image File history File linksMetadata Download high-resolution version (2000x960, 503 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Computer display Aperture grille Shadow mask Metadata This file contains additional information, probably added from the digital camera... Image File history File linksMetadata Download high-resolution version (2000x960, 503 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Computer display Aperture grille Shadow mask Metadata This file contains additional information, probably added from the digital camera... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... Electron gun from a cathode ray tube An electron gun is a component that produces an electron stream that has a precise kinetic energy, being used in all TVs and monitors which use cathode ray tube technology, and in other instruments, eg. ... For other uses, see Electron (disambiguation). ... This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen. ...


The image on the monitor screen is usually made up from at least tens of thousands of such tiny dots glowing on command from the computer. The closer together the pixels are, the sharper the image on screen. The distance between pixels on a computer monitor screen is called its dot pitch and is measured in millimeters. Most monitors have a dot pitch of 0.28 mm or less. Dot pitch (sometimes called line pitch or phosphor pitch) is a specification for a computer display that describes the distance between phosphor dots (sub-pixels) or LCD cells of the same color on the inside of a display screen. ...


There are two electromagnets around the collar of the tube which deflect the electron beam. The beam scans across the top of the monitor from left to right, is then blanked and moved back to the left-hand side slightly below the previous trace (on the next scan line), scans across the second line and so on until the bottom right of the screen is reached. The beam is again blanked, and moved back to the top left to start again. This process draws a complete picture, typically 50 to 100 times a second. The number of times in one second that the electron gun redraws the entire image is called the refresh rate and is measured in hertz (cycles per second). It is common, particularly in lower-priced equipment, for all the odd-numbered lines of an image to be traced, and then all the even-numbered lines; the circuitry of such an interlaced display need be capable of only half the speed of a non-interlaced display. An interlaced display, particularly at a relatively low refresh rate, can appear to some observers to flicker, and may cause eyestrain and nausea. An electromagnet is a type of magnet in which the magnetic field is produced by a flow of electric current. ... Wikipedia does not yet have an article with this exact name. ... A scanline is a line on a CRT tube, made up of dots. ... The vertical blanking interval (VBI) is an interval in a television or VDU signal that temporarily suspends transmission of the signal for the electron gun to move back up to the first line of the television screen to trace the next screen field. ... The refresh rate (or vertical refresh rate, vertical scan rate for CRTs) is the number of times in a second that a display is illuminated. ... This article is about the SI unit of frequency. ... Interlace is a technique of improving the picture quality of a video signal without consuming any extra bandwidth. ... Flicker has more than one meaning: A flicker is a type of woodpecker Flicker was bass guitarist for the Manic Street Preachers Flicker is a book by Theodore Roszak flicker occurs on a screen at low refresh rates. ...


Imaging technologies

19" inch (48.3 cm tube, 45.9 cm viewable) CRT computer monitor
19" inch (48.3 cm tube, 45.9 cm viewable) CRT computer monitor

As with television, several different hardware technologies exist for displaying computer-generated output: Image File history File links Size of this preview: 590 × 599 pixelsFull resolution (750 × 762 pixel, file size: 83 KB, MIME type: image/jpeg) 17:03, December 29, 2004 . ... Image File history File links Size of this preview: 590 × 599 pixelsFull resolution (750 × 762 pixel, file size: 83 KB, MIME type: image/jpeg) 17:03, December 29, 2004 . ...

“LCD” redirects here. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... It has been suggested that Vector monitor be merged into this article or section. ... The Vectrex is an 8-bit video game console developed by General Consumer Electric (GCE) and later bought by Milton Bradley Company. ... For other uses, see Radar (disambiguation). ... This arcade cabinet, containing Centipede, is an upright. ... Asteroids is a popular vector-based video arcade game released in 1979 by Atari. ... This article or section does not cite any references or sources. ... Raster can refer to either of the following items: Raster graphics, Bit array, the general-purpose data structure, or The scanning pattern of the electron beam to a screen of a Cathode Ray Tube. ... Composite video, also called CVBS (Composite Video Blanking and Sync), is the format of an analog television (picture only) signal before it is combined with a sound signal and modulated onto an RF carrier. ... For the musical use of modulation, see modulation (music). ... An example of a plasma display Composition of plasma display panel A plasma display panel (PDP) is a type of flat panel display now commonly used for large TV displays (typically above 37-inch or 940 mm). ... A surface-conduction electron-emitter display (SED) is a flat panel display technology that uses surface conduction electron emitters for every individual display pixel. ... Projected image from a video projector in a home cinema. ... A 3. ...

Performance measurements

The performance parameters of a monitor are:

  • Luminance, measured in candelas per square metre (cd/m²).
  • Size, measured diagonally. For CRT the viewable size is one inch (25 mm) smaller then the tube itself.
  • Dot pitch. Describes the distance between pixels of the same color in millimetres. In general, the lower the dot pitch (e.g. 0.24 mm, which is also 240 micrometres), the sharper the picture will appear.
  • Response time. The amount of time a pixel in an LCD monitor takes to go from active (black) to inactive (white) and back to active (black) again. It is measured in milliseconds (ms). Lower numbers mean faster transitions and therefore fewer visible image artifacts.
  • Refresh rate. The number of times in a second that a display is illuminated.
  • Power consumption, measured in watts (W).
  • Aspect ratio, which is the horizontal size compared to the vertical size, e.g. 4:3 is the standard aspect ratio, so that a screen with a width of 1024 pixels will have a height of 768 pixels. A widescreen display can have an aspect ratio of 16:9, which means a display that is 1024 pixels wide will have a height of 576 pixels.
  • Display resolution. The number of distinct pixels in each dimension that can be displayed.

Luminance (also called luminosity) is a photometric measure of the density of luminous intensity in a given direction. ... Look up size in Wiktionary, the free dictionary. ... Dot pitch (sometimes called line pitch or phosphor pitch) is a specification for a computer display that describes the distance between phosphor dots (sub-pixels) or LCD cells of the same color on the inside of a display screen. ... In telecommunication, response time is the time a system or functional unit takes to react to a given input. ... The refresh rate (or vertical refresh rate, vertical scan rate for CRTs) is the number of times in a second that a display is illuminated. ... In electrical engineering, power consumption refers to the electrical energy over time that must be supplied to an electrical device to maintain its operation. ... Various computer display standards or display modes have been used in the history of the personal computer. ... Display standards comparison The display resolution of a digital television or computer display typically refers to the number of distinct pixels in each dimension that can be displayed. ...

Problems

Dead pixels

A fraction of all LCD monitors are produced with "dead pixels"; due to the desire to increase profit margins by companies, most manufacturers sell monitors with dead pixels. Almost all manufacturers have clauses in their warranties which claim monitors with fewer than some number of dead pixels is not broken and will not be replaced. The dead pixels are usually stuck with the green, red, and/or blue subpixels either individually always stuck on or off. Like image persistence, this can sometimes be partially or fully reversed by using the same method listed below, however the chance of success is far lower than with a "stuck" pixel. Close-up of an LCD display, showing a dead green subpixel A dead pixel is a defective pixel that remains unlit on an LCD screen or a CCD or CMOS sensor in a digital camera. ... Close-up of an LCD display, showing a dead green subpixel A dead pixel is a defective pixel that remains unlit on an LCD screen or a CCD or CMOS sensor in a digital camera. ...


Phosphor burn-in

Screen burn-in, where a static image left on the screen for a long time embeds the image into the phosphor that coats the screen, is an issue with CRT and Plasma computer monitors and televisions. The result of phosphor burn-in are "ghostly" images of the static object visible even when the screen has changed, or is even off. This effect usually fades after a period of time. LCD monitors, while lacking phosphor screens and thus immune to phosphor burn-in, have a similar condition known as image persistence, where the pixels of the LCD monitor "remember" a particular color and become "stuck" and unable to change. Unlike phosphor burn-in, however, image persistence can sometimes be reversed partially or completely.[citation needed] This is accomplished by rapidly displaying varying colors to "wake up" the stuck pixels. Screensavers using moving images, prevent both of these conditions from happening by constantly changing the display. Newer monitors are more resistant to burn-in, but it can still occur if static images are left displayed for long periods of time. Phosphor burn-in seen at an airport terminal. ... Green screen A phosphor is a substance that exhibits the phenomenon of phosphorescence (sustained glowing after exposure to light or energised particles such as electrons). ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... An example of a plasma display Composition of plasma display panel A plasma display panel (PDP) is a type of flat panel display now commonly used for large TV displays (typically above 37-inch or 940 mm). ... Image Persistence is the term used for LCD Screen Burn. Like the burn-in on CRT monitors, image persistence on LCD monitors is caused by the continuous display of static graphics on the screen for extended periods of time. ... A stuck pixel is a common pixel defect on LCD screens. ... A screensaver is a computer program originally designed to conserve the image quality of computer displays by blanking the screen or filling them with moving images or patterns when the computers are not in use. ...


Other

With exceptions of DLP, most display technologies, especially LCD, have an inherent misregistration of the color planes, that is, the centres of the red, green, and blue dots do not line up perfectly. Subpixel rendering depends on this misalignment; technologies making use of this include the Apple II from 1976 [1], and more recently Microsoft (ClearType, 1998) and XFree86 (X Rendering Extension). The DLP Logo Digital Light Processing (DLP) is a technology used in projectors and video projectors. ... Subpixel rendering works by increasing the luminance reconstruction points of a color subpixelated screen, such as a liquid crystal display (LCD). ... The Apple II was one of the most popular personal computers of the 1980s. ... Year 1976 Pick up sticks(MCMLXXVI) was a leap year starting on Thursday (link will display full calendar) of the Gregorian calendar. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... ClearType is a registered trademark for a technology developed by Microsoft Corporation to improve the appearance of text on certain types of computer display screens, especially flat-panel displays. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... XFree86 is an implementation of the X Window System . ... The X Rendering Extension (Render or XRender) is an X Window System extension to implement Porter-Duff image compositing in the X server. ...


Display interfaces

Computer Terminals

Main article: Computer terminal

Early CRT-based VDUs (Visual Display Units) such as the DEC VT05 without graphics capabilities gained the label glass teletypes, because of the functional similarity to their electromechanical predecessors. A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system. ... DEC, dec or Dec may refer to: December - a month of the year in the Gregorian Calendar Department of Environment and Conservation Digital Equipment Corporation - a computer and technology company, now part of HP Declination - a term from astronomy Diethylcarbamazine - a drug commonly used to treat infections by filarial parasites... The VT05 was the first free-standing CRT computer terminal from Digital Equipment Corporation. ... For the journal by ACM SIGGRAPH, see Computer Graphics (Publication). ... A teleprinter (teletypewriter, teletype or TTY) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ...


Composite monitors

Early home computers such as the Apple II and the Commodore 64 used composite monitors. However, they are now used with video game consoles. The Apple II was one of the most popular personal computers of the 1980s. ... The Commodore 64 is the best-selling single personal computer model of all time. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... “Game console” redirects here. ...


Digital monitors

Early digital monitors are sometimes known as TTLs because the voltages on the red, green, and blue inputs are compatible with TTL logic chips. Later digital monitors support LVDS, or TMDS protocols. A Motorola 68000-based computer with various TTL chips. ... Low voltage differential signaling, or LVDS, is an electrical signaling system that can run at very high speeds over cheap, twisted-pair copper cables. ... Transition Minimized Differential Signaling (TMDS) is a technology for transmitting high-speed serial data and is used by the DVI and HDMI video interfaces. ...


TTL monitors

IBM PC with green monochrome display
IBM PC with green monochrome display

Monitors used with the MDA, Hercules, CGA, and EGA graphics adapters used in early IBM PC's (Personal Computer) and clones were controlled via TTL logic. Such monitors can usually be identified by a male DB-9 connector used on the video cable. The disadvantage of TTL monitors was the limited number of colors available due to the low number of digital bits used for video signaling. Download high resolution version (1024x740, 91 KB) IBM PC 5150 with keyboard and green monochrome monitor (5151), running MS-DOS 5. ... Download high resolution version (1024x740, 91 KB) IBM PC 5150 with keyboard and green monochrome monitor (5151), running MS-DOS 5. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... Green screen driven by a Monochrome Display Adapter The Monochrome Display Adapter (MDA, also MDA card, Monochrome Display and Printer Adapter, MDPA) introduced in 1981 was IBMs standard video display card and computer display standard for the PC. The MDA did not have any graphics mode of any kind... The Hercules Graphics Card (HGC) was a mid-1980s computer graphics controller which through its popularity became a de-facto display standard. ... The 640×200 2 color mode with its default foreground color — Arachne Internet suite. ... The Enhanced Graphics Adapter (EGA) is the IBM PC computer display standard specification located between CGA and VGA in terms of graphics performance (that is, colour and space resolution). ... A Motorola 68000-based computer with various TTL chips. ... A male DE-9 connector. ...


TTL Monochrome monitors only made use of five out of the nine pins. One pin was used as a ground, and two pins were used for horizontal/vertical synchronization. The electron gun was controlled by two separate digital signals, a video bit, and an intensity bit to control the brightness of the drawn pixels. Only four unique shades were possible; black, dim, medium or bright. The IBM PC with green screen Green screen was the common name for a monochrome CRT computer display using a green P1 phosphor screen. ...


CGA monitors used four digital signals to control the three electron guns used in color CRTs, in a signalling method known as RGBI, or Red Green and Blue, plus Intensity. Each of the three RGB colors can be switched on or off independently. The intensity bit increases the brightness of all guns that are switched on, or if no colors are switched on the intensity bit will switch on all guns at a very low brightness to produce a dark grey. A CGA monitor is only capable of rendering 16 unique colors. The CGA monitor was not exclusively used by PC based hardware. The Commodore 128 could also utilize CGA monitors. Many CGA monitors were capable of displaying composite video via a separate jack. For other uses, see Red (disambiguation). ... For other uses, see Green (disambiguation). ... For other uses, see Blue (disambiguation). ... Luminous intensity is a measure of the energy emitted by a light source in a particular direction. ... REDIRECT RGB color model ... The Commodore 128 (C128, CBM 128, C=128) home/personal computer was Commodore Business Machiness (CBM) last commercially released 8-bit machine. ...


EGA monitors used six digital signals to control the three electron guns in a signalling method known as RrGgBb. Unlike CGA, each gun is allocated its own intensity bit. This allowed each of the three primary colors to have four different states (off, soft, medium, and bright) resulting in 64 possible colors.


Although not supported in the original IBM specification, many vendors of clone graphics adapters have implemented backwards monitor compatibility and auto detection. For example, EGA cards produced by Paradise could operate as a MDA, or CGA adapter if a monochrome or CGA monitor was used in place of an EGA monitor. Many CGA cards were also capable of operating as MDA or Hercules card if a monochrome monitor was used.


Modern technology

Analog RGB monitors

Most modern computer displays can show thousands or millions of different colors in the RGB color space by varying red, green, and blue signals in continuously variable intensities. This article is about the machine. ... An RGB color space is any additive color space based on the RGB color model. ...


Digital and analog combination

Many monitors have analog signal relay, but some more recent models (mostly LCD screens) support digital input signals. It is a common misconception that all computer monitors are digital. For several years, televisions, composite monitors, and computer displays have been significantly different. However, as TVs have become more versatile, the distinction has blurred. Analog video is a term that can refer to any of three analog television (picture only) transmissions signals. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Configuration and usage

Multi-head

Main article: Multi-monitor

Some users use more than one monitor. The displays can operate in multiple modes. One of the most common spreads the entire desktop over all of the monitors, which thus act as one big desktop. The X Window System refers to this as Xinerama. Dual Apple Computer Cinema Displays Multi Monitor or Multi Head are synonymous terms referring to the use of multiple physical display devices such as monitors, televisions and projectors in order to increase the area available for computer programs running on a single computer system. ... “X11” redirects here. ... Four Head Xinerama Xinerama is an extension to the X Window System which allows applications and window managers to use the two (or more) physical displays as one large virtual display. ...

Two Apple flat-screen monitors used as dual display

Terminology: Image File history File links Dual Apple Cinema Displays Photo by Alastair Tse File links The following pages link to this file: Dual monitor User:NSR User:NSR/userboxes ... Image File history File links Dual Apple Cinema Displays Photo by Alastair Tse File links The following pages link to this file: Dual monitor User:NSR User:NSR/userboxes ... This article does not cite any references or sources. ...

  • Dualhead - Using two monitors
  • Triplehead - using three monitors
  • Display assembly - multi-head configurations actively managed as a single unit

Virtual displays

The X Window System provides configuration mechanisms for using a single hardware monitor for rendering multiple virtual displays, as controlled (for example) with the Unix DISPLAY global variable or with the -display command option. “X11” redirects here. ... In computer programming, a global variable is a variable that is accessible in every scope. ...


Major manufacturers

Acer (LSE: ACID) (Traditional Chinese: ) is a Taiwanese multinational electronics manufacturer. ... Apple Inc. ... BenQ Corporation (IPA: ; Chinese: ) is a Taiwanese company specializing in the manufacturing of computing, communications, and consumer electronics devices. ... Dell Inc. ... The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... Eizo Nanao Corporation ) (TYO: 6737 ), or EIZO, is a manufacturer of computer displays. ... Iiyama Corporation is a manufacturer of high end computer monitors and televisions, named after the city Iiyama in Nagano, Japan. ... LaCie is a computer hardware company specializing in external hard drives, RAID arrays, optical drives, and computer monitors. ... LG Electronics (Hangul:엘지전자, KSE: 066570, LSE: LGLD) is a South Korean multinational corporation and one of the worlds leading electronics companies. ... NEC Display Solutions is a manufacturer of computer monitors and large screen public information displays and has sold and marketed products under the NEC brand globally for over 20 years. ... Company logo Koninklijke Philips Electronics N.V. (Royal Philips Electronics), usually known as Philips, is one of the largest consumer electronics producers in the world. ... Samsung Group is one of the largest South Korean business groupings. ... Sharp Corporation ) (TYO: 6753 , LuxSE: SRP) is a Japanese electronics manufacturer, founded in 1912. ... Sony Corporation ) is a Japanese multinational corporation and one of the worlds largest media conglomerates with revenue of $66. ... ViewSonic is a manufacturer and provider of visual technology, specifically CRT monitors, liquid crystal displays, projectors, plasma displays, HDTV technology, and mobile products, including tablet PCs and wireless monitors. ... Westinghouse Digital Electronics LLC is an American company that manufactures LCD monitors and other consumer electronic products, licensing its name from Westinghouse Electric Corporation, a division of CBS Corporation. ...

See also

Electronics Portal

Image File history File links Nuvola_apps_ksim. ... A 3D display prototype by Philips A 3D display is any display device capable of conveying three-dimensional images to the viewer. ... The aim of Color calibration is to adjust the colours of one output device to match that of another. ... Various computer display standards or display modes have been used in the history of the personal computer. ... Screen less computing describes systems for transmitting visual information from a digital source or sources without the use of a computer screen. ...

External links


  Results from FactBites:
 
Apple - Cinema Displays (787 words)
Each display is designed to match the sculpted aluminum enclosures of Mac Pro and MacBook Pro.
While Apple displays leave the factory tuned to perform out of the box, you can use calibration devices to create a custom ColorSync profile.
A DVI connection removes the barrier to using an Apple display with your PC.
MERL – Privacy Enhanced Computer Display (307 words)
The privacy-enhanced computer display uses a ferroelectric shutter glasses and a special device driver to produce a computer display which can be read only by the desired recipient, and not by an onlooker.
The display alternately displays the desired information in one field, then the inverse image of the desired information in the next field, at up to 120 Hz refresh.
Background and Objective: The Privacy Enhanced Computer Display is appropriate for situations where a computer display is to be located in a publicly accessible area, but the display itself may show information that should be kept private.
  More results at FactBites »

 
 

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