​TFT LCD TOUCH PANELS

LED Backlight
Light Emitting Diode (LED): LED backlights are used primarily for character modules. They offer a longer operating life - 50,000 hours minimum - and are brighter than Els. They do consume more power than Els. Being a solid state device, they operate directly off +5 VDC, so they do not require an inverter. However, a current limiting resistor is recommended for protection of the LEDs. LEDs are mounted in an array directly behind the display, which increases the thickness 4 to 5 mm. LEDs come in a variety of colors, with yellow-green being the most common.

Cold Cathode Fluorescent Lamp (CCFL): CCFL backlight offers low power consumption and a very bright white light . Two technologies are used: direct an edge lighting. In both types a cold cathode fluorescent tube is the light source. A diffuser distributes the light evenly across the viewing area. Edge lighting offers a thinner package and less power. CCFLs require an inverter to supply the 270 to 300 VAC used by the CCFL tube. They are used primarily in graphic LCDs and have a longer life - 10,000 to 15,000 hours - than Els do.