Electroluminescent Display – Construction, Working, and Applications

The ELDs or Electroluminescent displays have their sources in scientific innovations in the 1st decade of the 19th century, although they did not develop into commercially feasible products till the year 1980.  These displays are mainly useful in applications like where full-color is not necessary however where high contrast, roughness, brightness, speed, and a wide-angle of observation is required.  Color Electroluminescent display technology has advanced extensively in current years, particularly for micro-displays. The two main companies that have invented commercialized ELDs are Planar Systems in the USA and Sharp in Japan.

What is an Electroluminescent Display Technology?

The electroluminescent display or EL display is the most widely used flat type display technology. Most popular display technologies like laser phosphor & LED works on the principle of electroluminescence. When the display is supplied with electrical energy, then semiconductor generates quantum of energy as well as photons. The result of this display comes from the recombination of the radioactive of holes and electrons with the electric charge influence.

Electroluminescent Display
Electroluminescent Display

In the light emitting diode, the doping-materials can form the PN- junction which divides the holes and electrons. When the flow of current supplies through the LED, then the recombination of holes and electrons takes place in resulting emission of the photon. Although in Phosphor type displays, the light emission mechanism is dissimilar. By the authority of the electric charge, the speed of the electrons will be increased for the emission of light.

Electroluminescent Display Construction

The electroluminescent display devices are similar to capacitors in many ways. The main difference among them is phosphor coating is used in these display devices. The construction of this display device can be done using flat solid electrode strips that are arranged parallel to each other & covered with one electroluminescent material layer like phosphorus, and then with another electrodes layer which are vertical to the layer at the ending.

The electroluminescent display devices consist of a thin layer doped with a semiconductor material, and it also has dopants to provide color. The materials used in electroluminescent displays are Gallium Arsenide, Blue diamond doped with Boron, Zinc Sulphide doped with Silver or Copper, etc.

Electroluminescent Display Construction
Electroluminescent Display Construction

These devices have two electrodes namely Glass-electrode as well as Back-electrode. The glass-electrode is the frontage transparent electrode which is covered by Tin Oxide or Indium oxide. The back electrode is covered by a reflective material. In between these two electrodes, the semiconductor material is placed.

Working of Electroluminescent Display

In these types of displays, using electric current the atoms will be stimulated to an excitation condition which results within radiation being produced in the visible light form. By changing the excitation stage of atoms, the exhibited color can be changed in the EL (electroluminescent) display. This display can be operated with an alternating current. The main feature of this display is, it provides a clear, wide viewing angle and a sharp picture. Most of the electroluminescent displays are monochromatic.

An ELD consists of a slight phosphorescent material film which is inserted among two plates, where one plate is layered with vertical wires & another plate is layered with horizontal wire. When the current flow through these wires, then the phosphorescent material between the two plates starts blinking.

An electroluminescent display looks like brighter than light emitting display and the surface brightness appears similar from all points of view. The light from the electroluminescent display cannot be calculated in Lumens because it is not directional. The light from this display is Monochromatic as well as it has a very thin bandwidth that is noticeable from a lengthy distance.

The electroluminescent light can be recognized well because the light is comparable. When the voltage is applied to this device, then it controls the output of the light. When the frequency as well as voltage increases, then the output of the light will also increase.

Advantages & Disadvantages

The advantages and disadvantages of electroluminescent display technology include the following.

  • Compact and Thin.
  • Writing speed is good.
  • It can be operated with Low-voltage.
  • Efficiency is low
  • Cost is high.
  • It has high-voltage drivers

 Applications of Electroluminescent Display Technology

The typical application of electroluminescent display technology is the automobile dashboard. These boards are used in audio devices and an electronic gadget which has displayed. It is also used in Audio equipment and other electronic gadgets having displays. The lighting of electroluminescent display device is better than LCD, and it is also used in watch dials, keypad illumination, Mobile phones, calculators, etc.

The utilization of power for EL display is extremely low. So it is the best solution for conserving power in battery functioned devices. The color of the electroluminescent display may be White, Green, and Blue, etc.

Some of the applications of electroluminescent display devices include wall mounted displays, bus stops, billboards, pos display stands, window displays, reception desks, vending machines, gaming machines, vehicle wraps, etc.

Nowadays, electroluminescent displays were very significant in the computer industry, medical military and industrial tools where high-brightness, contrast, speed, & ruggedness are required.  At present, the ELD industry is incomplete to two main players such as sharp and planar.  Most of the main research on electroluminescent displays remain in the commercial laboratories of Sharp and Planar; although some publicly funded investigate laboratories, as well as consortia, have also made significant donations to electroluminescent display technology. Here is a question for you, what is the working mechanism of ELD?

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