Plasma TVs are comprised of two sealed glass panels, which contain neon-xenon gas. Turning on a plasma TV charges the gas particles, striking red, green, and blue phosphors. Charging these gas particles creates the picture on screen. Panasonic televisions are some of the premier plasmas on the market.
LCD TVs are composed of two layers of transparent, polarised materials. One layer is coated with a polymer containing specialised individual liquid crystals. When one turns on an LCD TV, current passes through the crystals, which either allow light through or block it. This is what creates the image. To work, a source of light is necessary; manufacturers usually use fluorescent bulbs.
LED TVs are really a type of LCD TVs ? both use the same kind of liquid crystal display screens ? but Samsung televisions differentiated between “LED TVs” and LCD TVs and the naming caught on. The primary difference is their light source. Instead of fluorescents, LED TVs use light-emitting diodes, which allow for deeper blacks, better contrast, and a wider range of colour. There are two types of LED TVs: backlit (or full-array) and edge-lit.
Backlit/Full-array LED Televisions:
Backlit LED TVs contain rows of LEDs, spaced a few inches apart. A diffuser ensures that light spreads evenly across the screen. This spacing allows for “local dimming,” a process whereby LEDs can be dimmed individually or in groups. Local dimming allows dark portions of the screen to be darker while bright portions stay brighter, offering significant contrast improvements over LCD televisions. Because of this, backlit LED TVs match or surpass the contrast of plasma televisions.
Most manufacturers use white LEDs, but some Sony televisions use groups of closely-spaced coloured LEDs, which can potentially offer a wider range of colour. Sony televisions marketed with Triluminos technology have this arrangement.
Edge-lit LED Televisions
Edge-lit LED TVs have LEDs arranged along the edges behind the LCD panel. Light beams inward, toward the middle of the screen. A light guide plate then reflects the light outward to the viewer. Edge-lit LED TVs can utilise local dimming, but the LEDs can only be dimmed as a group. Thus, edge-lit LEDs can’t match the deeper contrast of backlit LED TVs, but they can be slimmer. At the very high-end, however, the difference in thickness can be negligible.
The choice of LED, LCD, or plasma TVs depends on individual needs, but sales of LED TVs are expected to outpace LCD TVs in 2014.