DIFFERENT TYPES OF DISPLAYS
1. Cathode Ray Tubes (CRT) Technology
This technology has been in use for more than 100 years, and is found in most televisions and computer monitors. Beams of electrons, from an electron gun are projected towards the fluorescent screen, within a vacuum, and each time it hits the screen, a phosphor dot lights up inside the glass tube, and thus illuminating active protons of the screen. Repetitions through the screen form a complete image. The image colour depends on the intensity of the three beams of RED, BLUE and Green. The screen is usually made of thick glass to prevent the emitting of x-rays to the environment. The tube has high stress due to the presence of the vacuum which can cause an explosion if the outer glass was to break. These types of screens are very hard to recycle because they have high concentration of lead and phosphors
2. Liquid Crystal Display (LCD) Technology
This technology uses the light modulating properties of liquid crystals. This display uses two sheets of polarizing material with a liquid crystal solution between them (thus the name liquid crystal display). An electric current passed through the liquid causes the crystals to align so that light cannot pass through them, acting like a filter. The screen is then put in front of a light source in order to produce images. When light falls on a pixel on the screen, the pixel appears black but change in the amount of voltage flowing in each pixels results in varying amount of light passing through the pixels. The other technology, called thin film transistor (TFT) or active-matrix, produces colour images that are as sharp as traditional CRT displays, but the technology is expensive. They are relatively less accurate in colour replication. LCD’s consume less energy as compared to CRT’s and they are easier to dispose and recycle. They have a small viewing angle and they tend to lose contrast in high temperature environments.

3. Plasma Technology
The screens create a picture from a gas (plasma) filled with xenon and neon atoms and millions of electrically charged atoms and electrons, that collide when you turn the power on. The collision increases the energy thus, release photons of light. It has a high contrast ratio and excellent color. Uses high power consumption and also high operating temperature. They have a wider viewing angle than the LCD. Their screens are made from glass that reflects more light thus causing more glare than the LCD screens. They emit high infrared charges hence regular infrared sensors cannot be used in the area. They cannot be used in high altitude areas due to the pressure difference between the gasses in the screen and the atmosphere. There is screen burn-in’s due to the projection of an image for a long period that causes the phosphors to overheat.
4. Light Emitting Diode (LED) Technology
This technology is based on the use of diodes. These diodes emit light upon the passing of an electric current. The diodes are usually placed between two electrodes, one being transparent. Unlike other technologies, they work without a backlight. This property makes them produce deeper levels of black and also allow the screens to be very thin and light. They have a wider viewing angle and produce better brightness and contrast than other technologies. They have a better response time giving a refresh rate of up to 100,000 Hz. They are expensive. Since they convert electrical energy to light energy, they are not very efficient outdoors. The LEDs get damaged when they are exposed to UV light for a long period. Water tends to damage the screen. The materials used are susceptible to decay over time, rendering the display unusable after some time hence has a short lifespan.