In my last article, I was discussing the basic pros and cons of plasma televisions. This week, I’ll write about the other common choices, light emitting diode (LED) and liquid crystal display (LCD) screens, while hopefully debunking some of the falsehoods floating around.
Comparing LED and LCD TVs can be very difficult, mainly because there really isn’t much of a difference. I’ll explain how an LCD screen works, then I’ll come back to how the two technologies aren’t very different at all.
An LCD screen functions at its most basic level by running an electrical signal through a transistor to one of three colours (red, green, and blue) in an individual pixel. By controlling the amount of voltage to each of the colours, you are able to create 256 individual shades for each of the colours, totalling close to 16.8 million possible colours.
Now for the interesting part. LCDs on their own do not generate light. You need either a reflective back layer, which is how digital watches work, or you need some type of backlight.
In TVs marketed as LCD, this backlight is a cold cathode fluorescent light (CCFL). These lights are typically run horizontally behind the screen, or mounted on the top and bottom, and they use a diffuser plate to distribute light over the entire screen surface.
So now that we know how an LCD screen works, why would I say that LED and LCD aren’t very different from each other? When you go into a store and look at a nice new LED screen, what you are actually looking at is an LCD screen using LEDs as the light source instead of a CCFL.
There are a few ways LEDs can be used to light a screen. Most commonly, LEDs are arranged behind the screen, shining out towards the viewer. In higher end sets, these lights can be turned on and off in specific areas to help produce better contrast. The other way the lights are used is in an edge-lit format. This design is what is used in the new ultra slim and frameless TVs on the market today.
There you have it! The difference between LED and LCD TV’s is really just the backlight. Both of these styles of TV function very well in varied lighting conditions, so if you don’t have a nice dark room to really make a plasma shine, LED or LCD may just be the screen for you.
Aaron Mackenzie is The Valley Echo’s technology columnist and the sales manager at The Source in Invermere. He can be reached at techracing@gmail.com.
