Plasma vs LCDs

I've been using a normal CRT TV and Monitor all my life, and honestly, I find them great. No doubt the slim, sexy appeal of a plasma and LCD (Liquid Crystal Display) TV or monitor has enticed me once or twice, but their prices have often put me off. Now, however, their prices are coming down, though they are what I would call cheap yet. So while I am not going to rush out and buy one soon, I thought that it'd be good to understand how plasma and LCD displays actually work, and which is better for the future?

Now the basics of the modern display is the pixel, which is basically a dot on the screen. However, I think many of us know, that this dot is actually not a single dot but 3 dots - one Red, one Green and one Blue(RGB). All displays, excluding projection displays, work on this same principle of the pixel, its just how they produce the light to generate the pixel's 3 primary colours.

Let's start with plasma displays. Plasma displays do this using the same principle that is used in our common household flourescent lights - plasma (duh!). Plasma is "a gas made up of free-flowing ions (electrically charged atoms) and electrons (negatively charged particles)." When an electrical current passes through the plasma, the negative particles within it get attracted to the positive terminal and rush towards it and vice versa for the positve particles. This movement results in collisions, that excite the gas atoms in the plasma causing them to release photons.

Different gases give off different wavelengths of such photons, but mostly within the ultraviolet range. Hence, to convert them into visible light, the plasma display uses phosphors of different colours. These phosphors line the walls of the thousands of cells that contain the gas in a plasma display. So when the corresponding cell is supposed to be lighted up, a current is passed through that cell, giving off the desired colour.

Now on to LCDs. LCDs use a special form of nematic liquid crystal, called twisted nematics (TN). Such TN crystals are naturally twisted and can be untwisted to varying degrees depending on the current applied to them. This predictable property is thus used to control the light in an LCD. This is done by placing the TN crystals between 2 polarising filters placed at 90 degrees to each other. This means that if the TN crystals aren't present, no light could pass throught the 2 filters. However, with the TN crystals, light is forced to bend around them, resulting in the final light wave being bent 90 degrees from the angle it came in. Hence, light can pass through the 2 filters.

Current can be applied to the crystals when there is a need to reduce the amount of light passing through, thus controlling the shade or contrast of the LCD. Colour LCDs work on the same principle, only that 3 different coloured lights are required to be produced to give the basic RGB pixel.

So which is better? In terms of age, the plasma display has been around for a tad longer than the LCD, which translates to a cheaper price. However, in terms of technology, older seldom means better. So lets take a look at the pros and cons of LCDs and Plasmas.

PLASMA PROS
Available in 50" & 61" Screens or larger?
Prices Dropping Everyday
Faster response times
Better colours
Wider viewing angle
Did we Mention Larger Sizes?

PLASMA CONS
Very Few Produce True Blacks
Still Images can Burn on Screen
Color Accuracy
Life Expectancy Shorter then LCD
Extremely Fragile
Most screens look pixilated
Most 60" plus Screens Overpriced
Artifact shows up on weaker signals

LCD TV PROS
Higher Native Resolutions
Extremely Detailed Picture
Extremely Thin (less then 2.25")
Brighter then Most Plasma's
Measured True Contrast Ratio's Surpasses Plasma Exaggerated #'s
Light Weight Champions
Extremely Resistant to Shock
Can't Burn Images (Burn Proof)
No Glare in Direct Sunlight
Lower Power Consumption
Longer Life Span (60,000 Hours)
Pixels much Smaller Producing a much Sharper, Defined Picture
True Black Levels

LCD TV CONS
Some What Expensive
Largest Screen Available 40
Smaller viewing angle
Slow reponse time creates motion blur/artefacts

It seems LCDs are the winner now. However, new technology is always coming up. So I wouldn't put my money on an LCD just yet. In any case, my trusty old CRT is still working fine, and probably will for the next few years. Till then, I'll be watching and waiting, and hopefully I may get an 21" LCD monitor for $100 or less! Haha!

Click here for more on Plasma Displays, here for more on LCDs and here for a comparison, plus a little discussion.