LED Message Center (c) Stickland Signs
Brightness levels affect visibility and lifetime of LED message centers. (Photo courtesy Strickland Signs)

Electronic Message Centers, known as EMCs, are becoming increasingly popular as on-premise display modules that advertise the goods and services provided at that location. The brightness level of EMCs is a topic of debate in the sign industry, for sign makers, sign users and the community at large. EMCs must be bright enough to be seen, but not so bright that they are illegible. The brightness must be balanced for optimum visibility, readability, and conspicuousness. Dr. Ian Lewin of Lighting Sciences has done extensive research for the International Sign Association in connection with EMCs. His full report can be found on www.signs.org, and a snip-it of it is quoted below:

"As a result of this research, the recommended brightness level for on premise EMCs is 0.3 foot candles above ambient light conditions when measured at an appropriate distance. This is a lighting level that works in theory and in practice."

The report goes on to detail the importance of proper brightness. Advantages connected to not overly bright signs are:
  • Conservation of energy
  • A legible display
  • A happy community
  • Increased life expectancy of the EMC
Technology can be of assistance when it comes to setting the brightness levels of EMCs appropriately, especially when it comes to making sure that signs are properly adjusted for nighttime viewing. The following three methods are used to adjust the brightness level on EMCs:
  1. Manual Dimming. As the name implies, the sign operator turns down the brightness level by hand according to the ambient light conditions.
  2. Scheduled Dimming. A sunset-sunrise table can be used to change the brightness level of the sign at the exact time of sunset and sunrise and dim and brighten the sun accordingly.
  3. Photocell Technology. This system uses a photocell sensor that notifies the display to change according to the ambient light conditions.