Sunlight and Outdoor Digital Signage – Protection Issues

While most screens placed outdoors, whether for outdoor digital signage, entertainment or to provide information, are protected from the elements, often in an outdoor LCD enclosure, many screens are still left vulnerable.

The sun can cause several problems, each the result of the differing radiation emitted from it. There are three types of radiation emitted from the sun that can cause problems for an outdoor screen: visible light, infra-red and ultra violet.

Visible light has perhaps the most obvious effect on an outdoor screen. Bright sunlight can overpower the backlight from an LCD making the screen look washed-out, low contrast and poor quality which can make the screen incredibly difficult to read in high ambient light conditions.

To counter this, high brightness TVs and other technologies are being implemented to ensure that outdoor screens are still readable – no matter what the ambient light. They either use very powerful backlights that emit three times the brightness of standard commercial screens or they use transflective technology that uses the sun’s own light to reinforce the image. Both these systems work adequately as well although more power is consumed by high brightness screens.

Heat is another problem caused by the sun for outdoor screens. The infra-red radiation from the sun is what provides us with heat. However, this radiation from the sun us also what creates internal heat build up, adding to the heat output from the TV.

To counter this problem of excessive sun-generated heat, an outdoor LCD enclosure with relevant cooling systems needs to be installed. It is also essential that the cooling fans or air conditioners need to be controlled automatically by thermostat.

Finally, ultra violet radiation is another problem for outdoor screens generated by the sun. Ultra violet radiation can discolour a screen when the sun is directly facing it. Greying and yellowing of the screen can result and the damage is permanent. Systems such as air curtains that blow cool air across the screen or some from of tinting are the only solutions to this problem.