How Flat Screen Computer Monitors are Constructed
All flat screen computer monitors, televisions, tablet PCs, and notebook displays use twisted-nematic/thin-film transistor, active-matrix, liquid crystal displays. The term “liquid crystal display” is where the acronym LCD comes from. Both LCD and LED monitors use this type of technology.
The Difference is in the Backlight
What makes LCD and LED monitors different is the type of backlight used. All flat panel displays have a backlight, usually at the base of the unit, which reflects light throughout the viewing surface to illuminate the screen for the user. Older flat panel monitors use a cold-cathode fluorescent (CCFL) tube to provide the backlight. A CCFL light is a type of fluorescent tube, which was the technology adopted to provide the backlighting in early-design flat screen displays. Often, when you see a monitor advertised today as a “LCD monitor,” it is using the older CCFL backlighting technology.
Why Manufacturers Switched to LED Backlights
The newer LED backlighting technology got its start in 2007, when Apple, Inc. announced that it would begin transitioning away from using CCFL tubes for backlighting in its displays, and instead use LED lights. The term “LED” means “light-emitting diode.” There were a number of reasons for switching to LEDs for backlighting:
- Helping the environment. CCFL tubes, like all fluorescent tubes, contain mercury vapor which is energized to create the lighting effect. The need for mercury is eliminated in LED backlit displays.
- Energy Savings. LED backlights require significantly less electrical power-about 40% to 50% less than CCFL backlights require. They also produce less waste heat.
- Simplification of Design. Switching to LED backlighting also enabled simplification of a monitor's design. Monitors with LED backlighting are slimmer and weigh less than CCFL backlit monitors, due to elimination of the fluorescent tube and its associated ballast.
Using LED Backlighting Enabled Performance Gains
Dynamic Contrast Ratio is the ratio of the luminance of the brightest color (white) as compared to the darkest color (black) that a monitor is capable of producing. CCFL backlights can only be dimmed so much and are limited in the dark contrasts they can provide. LED backlighting can be dimmed or even shut-down to provide pure-dark contrasts. This provides for more realism in dark scenes; such as in night-shots in movies or in dark rooms while gaming. Whereas the Dynamic Contrast Ratio of a CCFL backlight might be 100,000:1, for an LED monitor it can be 30,000,000:1. With high resolution LED monitors, the darker black levels enhance brightness for a more superb picture at all color levels.
LED lighting has taken the world by storm; in everything from light bulbs, to flashlights, and now in backlighting in flat panel displays. Maybe your next monitor will be one of the new LED monitors!