Electronic signs and electronics in general have made advances in the past
two decades to ease our way of life for the clock, and sign industry. See photo
of LED, Light emitting diode, electronic light source. below. Photo and information
Courtesy of www.howstuffworks.com
Since 1976, (the birth of the LED) evolution has taken shape! LED's were not
as attractive and useful as today. LED's first appeared in the form of scrolling
red messages on a black background, these were character matrix displays. In
the '80s, they evolved into three colors, red, amber, green or tri-color, or
a combinations of the three colors. These type of signs provided, "Cartoon
Looking", animation. LED's were more readily available as indoor signs
and outdoor units were not as economical as an incandescent displays, (light
bulb, or wedge based display). Not until the late '80s did LED's emerge as
a suitable outdoor technology, ie. bright enough, again, first in red pixels,
and later in the three-color format.
The '90s brought about the first true-color LED displays with the development
of blue and true-green LED's. These components were the missing link that prevented
LED's from serving as a suitable video medium. By 1996, blue and green LED's
had developed sufficient brightness for LED video screens and full-color animation
displays to become practical. By 1998, more than 50 companies produced these
products. Just like any other technology, at first LED signs were very expensive
until advances were made to bring prices down the incandescent level.
What is an LED?
Simply put, the light-emitting diode is a solid-state device, much different
than an incandescent lamp. It comprises an alloy crystal placed into a reflective
cup and chemically bonded to tiny wires, then encapsulated in epoxy. When electric
current runs through those wires, the crystal material is excited. That excitement
is dissipated in the form of energy, a small part of which is heat, most of
which is in the form of light.
Different alloys produce different colors. Each has its own life span and
brightness. LEDs' potential as a sign medium and light source has been known
from the start. Sourcing the proper chemicals and alloys has triggered intense
research for many years. The future of all forms of illumination is at stake.