How Does an LCD Display Work?
Liquid crystal displays (LCDs) are truly ubiquitous and have helped transition our society into an advanced digital age. The displays make up the faces of many popular consumable electronic devices, including TVs, watches, computer monitors, instrument panels, and more. If you have ever been interested in how these screens produce beautiful images, this blog will tell you everything you need to know about LCDs.
While LCD technology has only been widely available for a little over a half-century, the fundamental liquid crystals were discovered as early as 1888 when Austrian botanist and chemist, Friedrich Reintzer began experimenting with cholesteryl benzoate. He noticed in his experiment that the melted form of this substance could uniquely reflect polarized light while also rotating the direction of polarization. Substances that share these properties are unique in that they macroscopically appear as a liquid but actually have an organized crystalline structure at the microscopic level.
LCDs are made up of liquid crystals combined with polarizers, which are optical filters that create a well-defined polarization pattern for light. Since neither of the components can produce light independently, LCDs must also employ a backlight or reflector. In these displays, images are made up of millions of pixels, which are tiny units containing a blue, red, and green light that can be turned on or off using alternating current. Affixed to the back of the pixels are electrodes connected to a more complex network of circuitry. Depending on the command given to the numerous pixels, millions of stunning colors can be created in dynamic moving images.
Resolution is defined by the number of pixels the LCD contains. For example, if a monitor claims to have 1920x1080 resolution, it should contain 2,073,600 pixels. You may have noticed when viewing your computer's settings that it is possible to change the resolution as well. The recommended resolution, which is usually listed at the top, is the highest resolution your display can achieve. When the user changes it to a lower value, the graphics card merges pixels, thus lowering the total number.
LCDs are widely used because they have several qualities that make them more attractive than other displays. First, LCDs are much thinner than technologies like cathode ray tubes (CRTs), which predominated the TV market in the '60s-'90s. This fact has allowed TVs and computer monitors to transition from outdated, bulky designs to the sleeker models we see today. They are also immune to image burn-in, which occurs in displays using phosphorus-based compounds. Additionally, LCDs are much more power-efficient compared to other designs since they require less energy for light production. Finally, since LCDs use less power to display an image, they produce very little heat compared to other modalities.
There are some notable downsides to LCDs that other display types readily avoid. First, since LCDs employ polarizers to regulate the light path, the optimal viewing angle is very narrow. If one were to look at the display from the side, they might notice a decreased picture quality and color saturation. They also tend to be more expensive for the given size than other display technologies. Finally, LCDs struggle with producing dark gray and black images, thus decreasing the contrast and image quality in the context of a poorly-lit environment.
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