LCD TVs and LED TVs: Are They Really Different?

Nowadays, you can see a lot of people spending hours and hours together shopping for a perfect television which would occupy the center-stage of their respective living rooms. With the ubiquitous presence of ever-confusing marketers of the television-manufacturing companies, the decision is becoming all the more difficult. So, let us understand the technologies before you splurge your hard-earned money on them.

Earlier, you used to find televisions with only one kind of dauntless delete account technology. They were called ‘CRT TVs’ (Cathode Ray Tube). With the help of electron guns, coils and a fluorescent screen, the CRT TV was able to produce a viewable image. Now, there were problems with this technology:

1. A number of components were used to manufacture the television which made the processes of production, repair and maintenance difficult

2. The individual components were also bulky which made the television quite heavy

3. Some of these televisions had a problem of ‘Image burn-in‘ (Permanent discoloration of areas on electronic display) and a problem of ‘Image Loss‘ at the boundaries of the display

4. These televisions produced noticeable flicker at low refresh rates

5. They consumed high power and generated a lot of heat

To overcome the drawbacks of this technology, manufacturers started producing LCD (Liquid Crystal Display) televisions. An LCD is a flat-panel display that makes use of light modulating properties of liquid crystals. Now, these liquid crystals do not emit light by themselves, so a backlighting source is required in cases where there is higher power consumption. To understand this, you need to take note that there are two kinds of LCDs: ‘Passive Matrix LCDs’ and ‘Active Matrix LCDs’. In ‘Passive Matrix LCDs’ like ‘Alarm Clocks’ and ‘Calculators’ where the power consumption is less, a backlighting source is usually not required. Contrast this with ‘Active Matrix LCDs’, where some sort of backlighting mechanism is required. Now, this backlighting has been traditionally achieved with a ‘Cold Cathode Fluorescent Lamp’ (CCFL) in an LCD Television. So, the ‘CCFL backlit LCD’ television overcomes the problems of CRT in the following fashion

1. They don’t use phosphor. So, the problem of ‘Image burn-in’ is eliminated

2. They can be configured to run at high refresh rates. So, the problem of flicker is eliminated

3. When compared to the CRT television, the components used are lighter in weight, so the heaviness of the television is reduced

4. They consume lesser power and generate lesser heat while lighting the entire screen uniformly

5. There is no ‘Image-Loss’ at the boundaries and the entire screen is viewable

Consequently, manufacturers found out that they could improve upon these televisions too by changing the backlighting mechanism. They found that they could bring about the following changes

1. Reduce the power consumption even further

2. Reduce the thickness of the display even further

3. Increase the image quality even further

4. Increase the brightness of the display even further

5. Reduce the weight of the display even further

The manufacturers used LEDs (Light Emitting Diodes) as a backlighting source instead of the conventional CCFL sources and were able to achieve all-the-above stated objectives. So, this gave birth to the ‘LED backlit LCD’ televisions. Currently, if you go shopping for an LCD television, you won’t find a true LED TV. The only things you will find are ‘LED backlit LCDs’. So, don’t expect to see a radically different picture altogether as compared to a ‘CCFL backlit LCD’, albeit the images produced by the ‘LED backlit LCD’ televisions is in fact much better. Even these televisions can be further classified into 4 different categories.

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!

 

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