Buying guide: LED TVs
- — 01 June, 2009 14:00
Flat-screen televisions using LED technology are becoming more common. But compared to plasma and standard LCD TVs, what are the advantages of an LCD TV with LED backlighting — or LED television — and how do they differ to other televisions?
An LED television uses similar technology to a traditional LCD TV panel. The difference between LED and LCD televisions is that LCD televisions use cold-cathode fluorescent lights as backlighting for the screen — providing the white light that shines through the LCD panel to display colours — while LED televisions use large arrays of LEDs (light-emitting diodes) to create light. This means that unlike traditional LCD TVs, LED televisions can switch off segments of the backlight to achieve a much higher contrast ratio — meaning darker blacks and brighter whites.
Since LED televisions use an LCD panel, they generally have similar characteristics to LCD televisions in terms of sharpness, picture quality and fast-motion playback. However, their contrast ratios and colour reproduction are closer to plasma televisions.
What types of LED TVs exist?
Edge-lighting versus backlighting
LED televisions can use edge-lighting or backlighting. Backlit LED TVs use a sheet of LEDs to create white light evenly under the surface of the television screen. Edge-lit LED televisions, as the name implies, have individual clusters of super-bright LEDs aimed across the screen from the sides and corners of the panel.
While edge-lighting doesn’t allow the same segment-specific brightness adjustment as backlit LED televisions, edge-lit LED televisions are generally lighter and thinner, with many models less than two inches thick — the Sony BRAVIA KDL40ZX1 has a panel less than a centimetre thick. Unfortunately the picture quality is inferior compared to the backlit LED televisions we’ve tested.
RGB LED versus white LED
The other distinction that can be made is between LED televisions that use RGB LED lighting and those that employ white LED lighting. RGB LEDs — referring to the use of a red, a green and a blue LED in each cluster — have a wider colour gamut and slightly better performance in terms of colour accuracy, whereas white LEDs are cheaper and use less power.
LED TVs such as the Sony BRAVIA XBR45 series use an RGB LED backlight and have great colour saturation while the Samsung Series 9 (LA46A950) and other Samsung models use white LEDs, compromising on colour performance to reduce power consumption.
Why should I choose an LED TV?
LED televisions offer significant power saving advantages over traditional LCD televisions, with manufacturers listing power consumption figures up to 40 per cent lower. Newer LED televisions have energy star ratings of up to 6 stars, whereas most LCD screens have an energy star rating of 4 stars and equivalent plasma televisions generally have an energy star rating of 2 stars.
LED televisions are also more ‘green’ friendly than traditional plasma and LCD models because non-organic compounds (NOC) — such as mercury — are not used in their manufacture. This means that at the end of the TV’s lifecycle it is easier to recycle.
Another feature related to the power saving advantages of LED televisions is the long life span of the unit. With individual LEDs rated to up to 100,000 hours of life, LED televisions have a lifespan that can be significantly longer than traditional plasma televisions or CCFL-backlit LCD panels (which have an average life-span of 60,000 hours).
Weight and size
LED televisions are generally thinner than normal LCD TVs due to the absence of a bulky fluorescent backlight. This makes the LED televisions lighter and easier to transport; they weigh around two thirds of what a normal CCFL-backlit LCD television does. This also makes wall mounting easier as the panels are less obtrusive. Samsung’s latest LED televisions have a mounting system that only uses two screws and a picture-frame style wire to suspend the television with minimal damage to the wall.
Screen brightness can be adjusted to improve the onscreen image because the LED backlights can be switched on and off in segments, providing a much higher dynamic contrast ratio overall. This means images can have detail in dark black areas of the screen while showing high brightness in other segments. Picture quality in plasma displays has traditionally been superior to that of LCD televisions, but LED televisions have similar dynamic contrast ratios to newer plasma TVs — over 1,000,000:1 for high-end models.
Price and affordability
The main barrier to LED television adoption is the price point. LED-backlit televisions demand a price premium of 10 to 20 per cent compared to equivalent CCFL-backlit LCD televisions, and a similar premium over plasma televisions. Over the course of the next few years, the price of LED televisions will decrease as production costs decrease and a greater number of televisions are released. Due to their inherent advantages over CCFL, LED-backlit televisions will likely become the standard for television screens in the future.