Page 1LED display - Wikipedia, the free encyclopedia

7.8.2012 23:57:35http://en.wikipedia.org/wiki/LED_display

The 1,500-foot (460 m) long LEDdisplay on the Fremont StreetExperience is currently the largest inthe world.

The 40m large LED display at theArmin Only event on 19/20 apr 2008in the Jaarbeurs Utrecht

The LED Display at the Taipei Arenadisplays commercials and movietrailers.

LED displayFrom Wikipedia, the free encyclopedia

An LED display is a flat panel display, which uses light-emitting diodes as avideo display. An LED panel is a small display, or a component of a largerdisplay. They are typically used outdoors in store signs and billboards, and inrecent years have also become commonly used in destination signs on publictransport vehicles or even as part of transparent glass area. LED panels aresometimes used as form of lighting, for the purpose of general illumination,task lighting, or even stage lighting rather than display.

Contents1 Types

1.1 Flat panel LED television display1.2 The largest 3D LED television display1.3 LED text displays

2 See also3 References

TypesThere are two types of LED panels: conventional (using discrete LEDs) andsurface-mounted device (SMD) panels.[citation needed] Most outdoor screensand some indoor screens are built around discrete LEDs, also known asindividually mounted LEDs. A cluster of red, green, and blue diodes is driventogether to form a full-color pixel, usually square in shape. These pixels arespaced evenly apart and are measured from center to center for absolute pixelresolution. The largest LED display in the world is over 500 meters long and islocated in Suzhou, China, covering the Yuanrong Times Square.[citation needed]The largest LED television in the world is the Center Hung Video Display atCowboys Stadium, which is 160 72 ft (49 22 m), 11,520 square feet(1,070 m2).

Most indoor screens on the market are built using SMD technology[citationneeded]

a trend that is now extending to the outdoor market. An SMD pixelconsists of red, green, and blue diodes mounted in a single package, which isthen mounted on the driver PC board. The individual diodes are smaller than apinhead and are set very close together. The difference is that the maximumviewing distance is reduced by 25% from the discrete diode screen with thesame resolution.

Indoor use generally requires a screen that is based on SMD technology andhas a minimum brightness of 600 candelas per square meter (cd/m, sometimesinformally called nits). This will usually be more than sufficient for corporateand retail applications, but under high ambient-brightness conditions, higherbrightness may be required for visibility. Fashion and auto shows are twoexamples of high-brightness stage lighting that may require higher LEDbrightness. Conversely, when a screen may appear in a shot on a television

Page 2LED display - Wikipedia, the free encyclopedia

7.8.2012 23:57:35http://en.wikipedia.org/wiki/LED_display

A city trolleybus with LEDdestination signs

higher-brightness types of up to 5,000 cd/m cope even better with directsunlight on the screen. (The brightness of LED panels can be reduced from thedesigned maximum, if required.)

Suitable locations for large display panels are identified by factors such as lineof sight, local authority planning requirements (if the installation is to becomesemi-permanent), vehicular access (trucks carrying the screen, truck-mountedscreens, or cranes), cable runs for power and video (accounting for bothdistance and health and safety requirements), power, suitability of the groundfor the location of the screen (if there are no pipes, shallow drains, caves, ortunnels that may not be able to support heavy loads), and overheadobstructions.

Flat panel LED television display

The first true all-LED flat panel television screen was possibly developed,demonstrated and documented by James P. Mitchell in 1977.[1] The modular,scalable display was initially designed with hundreds of MV50 LEDs and anewly available transistor-transistor logic memory addressing circuit fromNational Semiconductor.[2] The in thin flat panel prototype and thescientific paper were displayed at the 29th ISEF expo in Washington D.C. inMay 1978.[3] It received awards by NASA,[4] and General MotorsCorporation.[5] A liquid crystal display (LCD) matrix design was also cited inthe LED paper as an alternative x-y scan technology and as a future alternatetelevision display method. The replacement of the 70 year+ high-voltageanalog system (cathode-ray tube technology) with a digital x-y scan system hasbeen a significant achievement. Displacement of the electromagnetic scansystems included the removal of inductive deflection, electron beam and colorconvergence circuits. The digital x-y scan system has helped the modern television to collapse into its current thinform factor.

The 1977 model was monochromatic by design. Efficient blue LEDs did not arrive for another decade. Large displaysnow use high-brightness diodes to generate a wide spectrum of colors. It took three decades and organic light-emittingdiodes for Sony to introduce an LED TV: the Sony XEL-1 OLED screen which was marketed in 2009.

The largest 3D LED television display

The 2011 UEFA Champions League Final match between Manchester United and Barcelona was broadcast live in 3Dformat in Gothenburg (Sweden), on an EKTA screen. It had a refresh rate of 100 Hz, a diagonal of 7.11 m (23 ft 3.92in) and a display area of 6.1923.483 m, and was listed in the Guinness Book of Records as the largest LED 3D TV.[6][7]

LED text displays

LED text displays refer to types that are specialized and limited to display of alpha-numeric characters. Most typesdisplay either one character or a group of characters. One character is generally displayed by a matrix of LEDs, or by amatrix of segments.

See alsoDot matrix displayAMOLEDLED-backlit LCD television

References