Liquid Crystal Displays (LCDs) have been around for many years now. For an image to be visible in low light levels, LCD panels require light to pass through them from behind. This is called a backlight. Conventional LCDs use cold cathode fluorescent tubes (CCFL) as their light source. Today, the most common way to backlight an LCD is by using light emitting diodes (LEDs). They present several advantages over CCFL tubes from power efficiency to improved contrast and colors.
LED backlit LCD TVs consume considerably less power than similarly sized plasma and CCFL backlit LCD TVs. Plasma displays do not have a backlight like LCDs do. Each pixel in a plasma display is its own light source. So, the higher the plasma display’s resolution, the more power it consumes. LCD power consumption does not depend on resolution as much as plasma displays do. It is more dependent upon size. LED backlit LCD displays use an array of LEDs to supply the light. The number of light sources is significantly less than a plasma display. As of April 21, 2010, the average power consumption for plasma TVs was 301 watts. The average power consumption for CCFL LCD TVs was 111 watts. For LED backlit LCD TVs, the average power consumption was 101 watts.
Another advantage that LED backlit LCD TVs pose over CCFL LCD TVs is their improved contrast. Contrast is the difference between the darkest blacks and the lightest whites. The improvement comes from the way the LEDs sit behind the LCD panel. The LEDs can be arranged in a grid, covering the back of the entire panel. A feature called Local Dimming allows each LED to be turned on and off independently. So in dark areas of a scene, the LEDs are turned off behind those areas and the blacks are blacker. In light areas of a scene, the LEDs can be brightened. Local Dimming can also save power.
LED backlit LCDs are the greenest TV choice at the moment.
