LED screen is a video display which uses light-emitting diodes. An LEDpanel is a small display, or a component of a larger display or screen. Theyare typically used outdoors in store signs and billboards, and in recent yearshave also become commonly used in destination signs on public transportvehicles. LED panels are sometimes used as form of lighting, for the purpose ofgeneral illumination, task lighting, or even stage lighting rather thandisplay.
Types of LED Screens:
There are two types of LED panels: conventional (using discrete LEDs) andsurface-mounted device (SMD) panels. Most outdoor screens and some indoorscreens are built around discrete LEDs, also known as individually mountedLEDs. A cluster of red, green, and blue diodes is driven together to form afull-color pixel, usually square in shape. These pixels are spaced evenly apartand are measured from center to center for absolute pixel resolution. Thelargest LED display in the world is over 1,500 foot (457.2 m) long and islocated in Las Vegas, Nevada covering the Fremont StreetExperience. The largest LED television in the world, the Center Hung VideoDisplay at Cowboys Stadium, is 160 by 72 feet (49 by 22 m), 11,520-square-foot(1,070 m2).
Most indoor screens on the market are built using SMD technology—a trend thatis now extending to the outdoor market. An SMD pixel consists of red, green,and blue diodes mounted on a chipset, which is then mounted on the driver PCboard. The individual diodes are smaller than a pinhead and are set very closetogether. The difference is that the maximum viewing distance is reduced by 25%from the discrete diode screen with the same resolution.
Indoor use generally requires a screen that is based on SMD technology and hasa minimum brightness of 600 candelas per square meter (cd/m², sometimesinformally called nits). This will usually be more than sufficient forcorporate and retail applications, but under high ambient-brightnessconditions, higher brightness may be required for visibility. Fashion and autoshows are two examples of high-brightness stage lighting that may requirehigher LED brightness. Conversely, when a screen may appear in a shot on atelevision studio set, the requirement will often be for lower brightnesslevels with lower color temperatures (common displays have a white point of6500 to 9000 K, which is much bluer than the common lighting on a televisionproduction set).
For outdoor use, at least 2,000 cd/m² is required for most situations, whereashigher-brightness types of up to 5,000 cd/m² 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 asline of sight, local authority planning requirements (if the installation is tobecome semi-permanent), vehicular access (trucks carrying the screen,truck-mounted screens, or cranes), cable runs for power and video (accountingfor both distance and health and safety requirements), power, suitability ofthe ground for the location of the screen (if there are no pipes, shallowdrains, caves, or tunnels that may not be able to support heavy loads), andoverhead obstructions.