LCD TVs and LED TVs: Are they really different? (Contd.) - 1

Yesterday, we discussed about the truth behind the LED TVs. Today, we’ll go further into the various categories of ‘LED backlit LCDs’ available in the market today.

Currently, ‘LED backlit LCDs’ are available in the market in 2 varieties: ‘Edge-Lit’ and ‘Full-Array’. In an ‘Edge-Lit LED backlit LCD’, LEDs (Light Emitting Diodes) are present in the entire perimeter (periphery) of the television. The backlighting of the screen is achieved with the help of what are called ‘Light Guides’. These ‘Light Guides’ direct the glow towards the center of the screen.

The following are the advantages of these kinds of televisions:

1. They are very thin (as much as 40% thinner) when compared to ‘CCFL backlit LCDs’
2.  They consume much less power (as compared to the ‘CCFL backlit LCDs’
3. They are also very much lighter in weight (In fact, most of them could be wall mounted)
4. They can produce a bright image with very nice colors and deep blacks

The following are the disadvantages:

1. The entire screen may not be lit uniformly (The edge of the screen may be brighter than the middle of the screen)
2. True blacks may not be achieved consistently across the entire screen

In fact, both the varieties: ‘Edge-Lit’ and ‘Full-Array’ LED backlit LCDs have the capacity to produce deep blacks as the LEDs could be simply turned off when no color is being reproduced on the screen.

Now, for the ‘Full-Array LED backlit LCDs’: In these kinds of televisions, several rows of LEDs are placed behind the entire surface of the screen.

The following are the advantages of these kinds of televisions:

1.  They are thinner (as compared to the ‘CCFL backlit LCD’ variety)
2. They consume much less power (as compared to the ‘CCFL backlit LCD’ variety)
3. They are lighter in weight (Again, as compared to the ‘CCFL backlit LCD’ variety)
4. They can produce ‘True Deep Blacks’ (as compared to both ‘CCFL backlit LCD’ and ‘Edge-Lit LED backlit LCD’)
5.  The brightness and colors are better (as compared to both ‘CCFL backlit LCD’ and ‘Edge-Lit LED backlit LCD’)

The following are the disadvantages of these kinds of televisions:

1. ‘Blooming Effect’ (described below) affects the picture quality a little bit
2. Slightly thicker and heavier (as compared to the ‘Edge-Lit LED backlit LCD’)

The reason that ‘Full-Array LED backlit LCD’ can achieve truer blacks is because whenever blacks have to be reproduced on a significant portion of the display, an entire section of LEDs can be turned off without affecting the display properties of the other LEDs. This property is widely known by the name: ‘Local Dimming’. So, local dimming leads to better blacks but also leads to an effect called ‘Blooming’. If a bright color (LEDs turned on) is being displayed inside a black section (LEDs turned off - Local Dimming), the bright color creeps slightly into the adjacent black portion (like a halo). This effect is called ‘Blooming’. But hey, it is ever-so-slightly-noticeable.

So, there are 4 kinds of ‘LED backlit LCDs’:

1. ‘Edge-Lit LED backlit LCD’ without ‘Local Dimming’ 
2. ‘Edge-Lit LED backlit LCD’ with ‘Local Dimming’
3.  ‘Full-Array LED backlit LCD’ without ‘Local Dimming’
4.  ‘Full-Array LED backlit LCD’ with ‘Local Dimming’ (Usually, the best of the lot)

I’ll again reiterate. There is no ‘True LED TV’ available commercially in the market right now. A 'True LED TV' can be defined as follows:

“Each and every individual pixel should have the capability of being independently brightened or turned off. For this to be achieved, an LED has to be present for each and every pixel. Currently in the market, a ‘Full-Array LED backlit LCD’ with ‘Full HD’ (having a resolution of ‘1920 * 1080’), has only a maximum of 2000 LEDs. If it has to qualify for being a ‘True LED TV’ there should be 2073600 LEDs.”

So, go get your TV right now.

Stay Tuned..!!