How does a large area LED display work
LED display is an active display device, its active elements being light emitting diodes, abbr. LED assembled in a matrix covering the whole display area. A LED display is based on the colour addition principle where each individual full-colour point is formed by three LEDs – red, green and blue. Due to limited resolution ability of human eye, when watching from a certain distance, the lights of all three LEDs merge and the viewer perceives them as a single coloured point. The longer the diode pitch, the longer is also the minimum viewing distance.
LEDs are arranged in the display area with sunshades. The sunshades are small roofs over LEDs preventing from sunlight incidence and protecting from mechanical damage. The black colour of display background provides optimum conditions for a maximum utilisation of colour range and intensity of emitted light. Using different light intensities of the individual LED up to 68 billion colours can be created!
Image data are processed in computer by a control application that assigns each diode a different brightness. This information is sent into the control unit inside the display itself. All this happens in real time at a refresher rate
of 600 H,i.e. 600 times a second. The high refresher rate guarantees that the image of the LED display, recorded by any video device, does not flicker, which is absolutely necessary for TV transmissions from sports events or concerts.
Elements of large area LED displays
- Cluster is the smallest design element of large area displays. It is
a waterproof and dustproof segment of size 12x12x2.5 cm containing LEDs arranged in a matrix, control electronics and a jacket made of resistant plastic. Each cluster has a doubled connector with base block to prevent loss of data going to LED. A damaged cluster can be readily replaced even with the display in operation. - Base block is the basic functional element of large area LED displays. It consists of a base board with control electronics, primary and stand-by power supply unit and a robust metallic case. Its front side is populated with 16 clusters (4x4). A large area LED display of any shape and size can be assembled from these base blocks – the only limitation is the size of the base block 48 x 48 cm.
- Framework connects base blocks in a single mechanically resistant unit. There is a choice of either fixed construction suitable for permanent installations such as on building walls, or dismountable construction allowing to change the shape of display as needed (modules of approx. 1x1 m can be assembled into any shape).
- Data cable is used to for communication between the control computer and the large area LED display. The type used is either a conventional metallic network cable or an optical cable for remote control (in order of kilometers).
- Control computerprocesses visual information from various inputs by means of the #70 ViewLab application /#and sends it then to the control electronics of the display. As a control computer there can be used a standard PC equipped with cards for collecting video signals (both S-Video and composite video), for digital and analogue TV, satellite broadcast, etc. The ViewLab application allows combining video signal from cameras with graphics and texts, advertising messages, information blocks containing internet online reports or SMS chat or spectator SMS voting.
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