LCD vs. Plasma Technology

Flat panel TVs are different in the sense that their screen is flat compared to a traditional CRT Television that has a curvature. Their width is also smaller than traditional TVs since they do not use CRTs(Cathod Ray Tube) technology for picture production. Currently, the two most popular types of flat panel televisions are Liquid Crystal Displays(LCDs) and Plasma TVs. There are lot of tests and reviews out there trying to find answer to Plasma vs LCD puzzle.

 

Flat Panel TV : LCD

A LCD (which stands for “liquid crystal display”) is one of the most popular type of flat panel television. Its main rival (in terms of popularity and usage) is the Plasma TV, and comparisons between the two have often been made. A LCD is a thin display device that is made of glass sheets filled with liquid crystals. These crystals are actuated by electrical charge that twists and turns them to form the desired image on the screen. Most LCD TVs use TFT (thin-film transistor) technology. Also, some LCD models (mostly recent releases) use Bluetooth or WiFi technology to connect to a host computer.

 

True to its status as a flat panel display, a LCD is sleek and slim. Though it is usually smaller than a plasma television, a LCD uses a very small amount of electric power, making it the apple of the eyes of engineers and the power consumption-conscious. Even though LCD has been smaller than plasma television in size, that gap is filling up quickly as more and more technological advancements are made. Sharp recently announced a 105 inch LCD Flat panel TV.

LCDs can be used both as televisions and as computer monitors, making them very versatile. However, LCDs suffer from poorer picture quality when compared with plasma TVs; LCDs fare poorly at high viewing angles as well. Viewing angles are measured in horizontal and vertical planes.

 


Flat Panel TV : Plasma

Plasma TV screen is made of two separate glass sheets. These two sheets are divided by barrier ribs splitting the screen vertically and horizontally. End results is thousands of individual sections called "cells". Each cell is then coated with Red, Green and Blue phosphor. One horizontal set of Red, Green and Blue (RGB) cells makes up a pixel. In the final process, each cell is filled with a inert gas such as neon or xenon. To supply electricity to these cells, two kind of electrodes are used - address electrodes, running at the back of the flat panel and display electrodes, running at the front of the panel. These electrodes run perpendicular to each other. When electricity is passed thru these electrodes, it causes gas mixture to emit ultraviolet radiation. This process is complex but in simple terms it is very similar to the xenon lights you see on some of the new vehicles. This radiation then excites the phosphor coating causing it to glow and produce RGB light. Most complex part of the system is the controller that can switch on and off each individual cell as required by the picture.

 

Whole plasma screen is divided in hundreds of horizontal lines of RGB cells. Each row is powered by two end electrodes to form a picture. In standard 720p resolution screen, each row is powered by its own electrodes, while in 1080p format, odd and even number rows share an electrode. This enable manufacturers to insert more rows in the space between teo adjacent rows on the screen, thus making a lot more smoother picture.

 

A plasma TV is usually brighter than its counterpart (LCD). Plasma panels can also be used as computer monitors but some lower end model may suffer from "burn-in". A "burn-in" is the term used for permanent image retention on the flat panel screen. This usually happens when a picture has a section that always stays the same. For example, CNN logo on the lower right corner of their broadcast. Plasma TVs can have a lifespan of about 7 years. However, this depends on proper use and maintenance. For example, setting the display to a high contrast setting tends to shorten its life. In long run, phosphor material decays and loses its brightness. Plasma set uses most power when showing a lighter color picture or white background. Ultraviolet radiation increases in intensity as applied voltage is increased, that's why some of the lower end plasma TVs have a audible buzzing sound when they display white or lighter color images. Pioneer PureVision Plasma and Samsung Plasma sets are best but Panasonic plasma sets are catching fast.

 

Even though LCD and Plasma are two dominant technologies in High Definition market, there is another technology out there. It is known ad DLP or Digital Light processing. It uses millions of small mirrors to reflect light and achieve desired image. There is lot of reference material available on LCD vs. DLP or Plasma Vs DLP. It is a decent option if you have a low budget but size and weight is a big concern with DLP sets.