What is LED Backlighting?
I hear you talk about LED backlighting and edgelighting in LCD TVs, and I can’t seem to find which one my Samsung UN60D7000 uses. I thought it was backlit, but hearing you talk about it made me wonder if I was right.
All TVs in Samsung’s 2011 lineup, including the UN60D7000, use LED edgelighting, with LEDs located along the edges of the screen—in this case, the side edges, not the top and bottom. By contrast, LCD TVs that use LED backlighting have an array of LEDs directly behind the LCD screen. Technically, both are “backlighting,” since the light passes through the LCD panel from behind. The difference is where the LEDs are mounted—along the edges (with a diffuser that bends the light to pass through the LCD panel) or behind the panel.
Few companies make LED-LCD TVs with true backlighting, primarily because edgelighting allows the TVs to be thinner, which seems to be what consumers want. However, these sets almost always suffer from uneven illumination in dark scenes, an effect sometimes labeled poor uniformity.
One advantage of backlighting is a feature called local dimming, in which the LEDs behind dark parts of the image are dimmed while those behind bright parts are brightened, greatly increasing perceived contrast. In essence, the LEDs form a low-resolution, black-and-white version of the high-resolution image on the LCD panel, as depicted above. (Samsung’s 2011 and 2012 models use a form of electronic “local dimming” to increase contrast.)
However, not all LED-backlit sets implement local dimming—for example, Sharp’s current, non-Elite LED-backlit models and Samsung’s 2012 entry-level EH series. LED-backlit sets that do implement local dimming include the Sharp Elite, Sony HX929, and several Vizio models. These sets are typically more expensive than comparably sized LED-edgelit models, but if someone is shopping for an LED-LCD TV, I generally recommend spending the extra dough for local dimming if possible and living with a slightly fatter flat panel.