CS101 Computer Basic
Topic 11: Different types of Monitor
CS101 Computer Basic
The monitor is the most commonly used output device. It looks like a Television but has a much higher resolution. Nowadays, many different types of small and large monitors are available in the market. We can classify these monitors into various categories based on shape, size, resolution, refresh rate, aspect ratio, connection ports, etc.
Based on technology, the monitors are mainly of three types –
Cathode Ray Tube (CRT) Monitors
CRT monitors are the oldest type of monitors. This technology has been used since 1950. In these types of display, a CRT or cathode ray tube is used. CRT is basically a glass vacuum tube containing an electron gun at one of its sides. A fluorescent screen is installed in front of the gun on the other side. The gun blasts a high-speed electron beam or cathode rays towards the fluorescent screen. When the collision occurs, the screen flashes for a moment. On this fluorescent screen, the beam is fired continuously from left to right and top to bottom. The image is similarly refreshed multiple times in a second.
Although these monitors are very trustworthy and affordable, more power is required to operate and generate a lot of heat. The eyes also get tired very soon due to the continuous electromagnetic radiation emitted from them. Moreover, being very large and heavy, it is not possible to install them in portable computers. Because of all these drawbacks, these monitors are outdated nowadays. Most of them have been replaced by new LCD and LED monitors.
Liquid Crystal Display or LCD Monitors
Liquid Crystal Display or LCD monitors are lighter, thinner, and consume less amount of power. They are used in all types of computers as well as television, mobile phone, etc. Such monitors use liquid crystals to produce the image. Liquid crystals are a substance that is permanently in a liquid state. But it has some properties inherent in crystal bodies. As liquid crystals don’t produce any light, they need a light source but can modulate the light traveling through it.
The liquid crystal display consists of several different layers. It includes a light source, two polarizer films, a liquid crystal layer, and electrodes. On the backside of the LCD, a fluorescent lamp produces a huge bright light. That is passed through a vertical polarizer film, which allows only vertically polarized light to pass. After that, the light coming from the polarizer is passed through a liquid crystal element. This element twists the light at an angle of 90 degrees in natural conditions. Which can easily pass through the horizontal polarizer film on top of it and appears on the screen. But when a voltage is applied between the electrodes, it does not twist the light. So the light is stopped by the polarizer and is not visible on the screen.
Using this technique, different pixels are generated, which together make up the entire display.
Light Emitting Diode (LED) Display
All LED monitors are LCD monitors. The only difference is in the backlight. While a typical LCD monitor uses a fluorescent lamp backlight, an LED monitor uses multiple small light-emitting diodes for the backlight. The LED monitor offers a brighter display with a high contrast ratio while consuming less power.