LCD TV’s require a backlight to illuminate the picture that is being shown. In normal LCD TV’s, this light is provided by fluorescent backlights called CCFL. Now, LED lights are being used instead of CCFL’s because they consume less power and enable manufacturers to come up with thinner models.
Edge lit (without local dimming) – This is what you generally get in the market. The LED’s in this type of TV are set around the edge of the screen. The center of the screen is illuminated with the help of “light guides”. The picture quality on this is the same as a normal LCD, but you will have certain problems like brighter edges and a dimmer center.
Full Array (without local dimming) – This model is rather rare and obviously a bit more expensive to make due to its component cost. Here LED’s are found everywhere behind the screen and not along the edges. This means that can be no dark spots like in the edge lit version. Picture quality is the same as a normal LCD TV.
Full Array (with local dimming) – This is the same as the previous model with one significant exception. Individual areas in the LED array can be brightened or dimmed as dictated by the signal. Due to the black levels can be far superior to those in normal LCD’s. However, it also leads to “blooming” (light spill) issues too. In spite of that, this remains the most desirable model to purchase.
Edge lit (with local dimming) – This model is still not perfect. It tries to do what the preceding type does, but rather unsuccessfully. Attempting to dim with edge lighting gives way to a lot of “blooming” issues. The best thing to do is to avoid this model.