LED panels

There are two types of LED panels: conventional, using discrete LEDs, and surface mounted device (SMD) panels. Most outdoor screens and some indoor screens are built around discrete LEDs, also known as individually mounted LEDs. A cluster of red, green, and blue diodes is driven together to form a full-color pixel, usually square in shape. These pixels are spaced evenly apart and are measured from center to center for absolute pixel resolution. The largest LED display in the world is over 1,500 foot (457.2 m) long and is located in Las Vegas, Nevada covering the Fremont Street Experience.

Most indoor screens on the market are built using SMD technology—a trend that is 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 PC board. The individual diodes are smaller than a pinhead and are set very close together. 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 has a minimum brightness of 600 candelas per square meter (cd/m², sometimes informally called "nits"). This will usually be more than sufficient for corporate and retail applications, but under high ambient-brightness conditions, higher brightness may be required for visibility. Fashion and auto shows are two examples of high-brightness stage lighting that may require higher LED brightness. Conversely, when a screen may appear in a shot on a television show, the requirement will often be for lower brightness levels with lower color temperatures (common displays have a white point of 6500 to 9000 K, which is much bluer than the common lighting on a television production set).

For outdoor use, at least 2,000 cd/m² is required for most situations, whereas higher-brightness types of up to 5,000 cd/m² cope even better with direct sunlight on the screen. (The brightness of LED panels can be reduced from the designed maximum, if required.)

Suitable locations for large display panels are identified by factors such as line of sight, local authority planning requirements (if the installation is to become semi-permanent), vehicular access (trucks carrying the screen, truck-mounted screens, or cranes), cable runs for power and video (accounting for both distance and health and safety requirements), power, suitability of the ground for the location of the screen (if there are no pipes, shallow drains, caves, or tunnels that may not be able to support heavy loads), and overhead obstructions.

LED TV Panel - History

Perhaps the first recorded flat panel LED television screen developed was by J. P. Mitchell in 1977 [Mitchell's LED television design was cited in the 29th International Science and Engineeting Exposition "book of abstracts", page 97, published by the "Science Service", Washington D.C. in May of 1978. ] . The modular, scalable display array was initially enabled by hundereds of MV50 LEDs and a newly available TTL (transistor transistor logic) memory addressing circuit from National Semiconductor [A technical reference detailing the LED diplay array, RF interface and scanning circuit was included as part of the 1978 29th ISEF exhibition in Anaheim Ca. The original documents are kept with the prototype.] . The 1/4 inch thin flat panel prototype and the scientific paper were each displayed. [The prototype and scientific paper "Light Emitting Diode Television Screen" were part of exhibit #635. The original technical paper is kept with the original working prototype.] at the 29th Engineering Exposition in Anaheim May 1978, organized by the Science Service in Washington D.C. The LED TV display received awards and recognition from NASA [Honorable Mention - NASA, 29th ISEF "Announcement of Awards", page 4, Saturday May 13th 1978, published by the Science Service 1719 N Street Washington D.C. 20036.] , General Motors Corporation [3rd Grand Award - GM, corporate sponsor of the 1978 Science Service event. 1978 29th Annual ISEF "Announcement of Awards", page 5, (note: Intel corporation is the current sponsor of this event).] , and faculty from area Universities [Reference; the project witness log, a non-published signature list maintained with the original display materials. A second reference listing sponsors and judges: Science Service, 29th ISEF "Program of Events", pages 9, 10 and 11.] . The event was open to technology and business representatives from the U.S. and overseas. The monochromatic prototype remains operational. A LCD (liquid crystal display) matrix design was also cited as a future flat panel TV possibility in the accompanying scientific paper as a future alternate television display method using a similar array scanning design.

In order to develop a color display, efficient blue LEDs were needed. Efficient blue LED's did not emerge until the early 1990s completing the desired RGB color triad. High-brightness colors gradually emerged in the 1990s enabling new designs for outdoor signage and huge video displays for billboards and stadiums.

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