How Does a Computer Monitor Work?

When it comes to building your computer setup, a monitor is often bought without much consideration. Whether you’re buying a monitor for work or personal use, it’s important to learn the basics of how a computer monitor works to be able to choose one that would do the job correctly based on your needs.

How Computer Monitors Work

Generally speaking, a monitor was designed to accurately and clearly display the text, images, video, and other information from a program, software, or files.

Monitors are built with the concept of how our eyes (and brain) perceive images. Images are divided into thousands of smaller, colored dots (known as pixels), which the brain will then reassemble into a distinguishable image.

When you find a monitor with a resolution of 800 x 600 pixels, multiply the numbers 800 x 600 to get 480,000. The answer (480,000) refers to the number of dots or pixels you can see on your monitor if you look close enough. When the monitor lights up these dots, the brain can see the 480,000 dots as a complete image (and not at separate dots).

All the types of monitors, namely CRT, LCD, LED & TFT,  work the same way in showing pixels, except the manner in which they light up the dots differ.

Types of Monitors: CRT, LCD, LED & TFT

Monitors use different technologies and the types are categorized as such:

CRT (Cathode Ray Tube)

  • PROS: cheaper, durable, advanced gradation between colors
  • CONS: prone to fuzzy images and geometric distortions

CRTs are designed with a large vacuum tube at the back and a cathode (with heated filament pointing toward the viewer). The filament becomes an electron gun that fires off electrons as it receives visual signals from your computer. There’s a glass plate in front of the monitor, which is where millions of phosphor dots will be lit up. When signals go through the electron and then to the magnet and hit these phosphor dots, it will make differently-colored dots/pixels glow (this is what your brain will see as an image).

LCD (Liquid Crystal Display)

  • PROS: lighter, compact, energy-efficient, better resolution, minimal heat
  • CONS: limited viewing angles, may suffer from uneven backlighting

LCD monitors use LCD technology, wherein two specially-treated polarized-glass plates are pressed together and sandwich liquid crystal material. Whenever signals are sent to the display, an electric current allows various light wavelengths across the surface, creating light on specific areas. Our brain then interprets these colors and dark spots as images.

LCDs have replaced CRTs over the years because of the improvement of color accuracy, picture quality, and capabilities for larger resolutions. These displays also are space-savers because of the flat panel design (as compared to the curved CRT design).

LCD monitors use a fluorescent backlight. LED (as well as OLED and QLED) are forms of LCD monitors. They work the same way, except for the type of back-lighting they use.

QLED (quantum dot light-emitting diode) is considered an upgrade of LCD technology, but OLED (refers to organic light-emitting diode) uses a completely different technology, specifically a carbon-based film sandwiched by two conductors that emit its own light whenever electric current passes through it.

LED (Light Emitting Diodes)

  • PROS: slim design, flicker-free images, better color and image accuracy, energy-efficient, longer lifespan
  • CONS: inconsistent contrast ratio, more expensive than LCD

All LED monitors are LCD monitors. But not all LCD monitors are LEDs. Both these displays use liquid crystals in creating images, but as I mentioned earlier, LEDs uses light-emitting diodes for backlighting, while LCDs use flourescent.

LED monitors are built with hundreds of closely-positioned LEDs, each with varying brightness.

These LEDs will form the images. For example, if the computer tells it to show a brightly-colored image, the display “mixes” LED light (in red, green and blue) to showcase the exact color pattern needed to form the pixel/pixels. The monitor can simultaneously adjust billions of brightness/darkness of diodes and mix RGB colors, so that your brain can see the image from a certain distance.

TFT (Thin Film Transistor)

  • PROS: energy-efficient, sharper text, faster response time
  • CONS: viewing angles, expensive

TFT monitors fall under LCDs and uses simple chemical and electrical concepts in creating images on a screen. The electrical charge it utilizes cause liquid crystals to change their molecular structure, which then allow backlight to pass through the doble layers of glass panels and display the pixels.

As you can see, each of these monitor types has its pros and cons. While CRTs are not the go-to standard of computers for home use and offices, they are still used in imaging and laboratory equipment. LCDs and the displays that fall under this category (such as LEDs) are more popular thanks to the technological advancements and better image accuracy they provide.

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