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 founding of LED technology) 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. As time passed, production numbers increased, to generate the need for higher quantities of LED's the price and applications for LED's began to drop.
The 90s brought about the first true-color LED displays with the development of blue and true-green LED's. Video screens began to pop up with LED technology and jumbo tron type screens began to fall off the face of the earth. Colored LED's 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 display 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.