A flat-screen television is now accepted as the standard hardware for visual entertainment. Behind the sleek lines and minimalist proportions are remarkable technology and electronic engineering. The backlighting of your screen, in particular, can transform the intensity and contrast of colors for an exceptional viewing experience.
There is a wide range of backlighting options for the LCD technology that is commonly used in TV screens. Common backlighting solutions include:
- Light-emitting diodes (LED)
- Electroluminescence panels (ELP)
- Cathode fluorescent lamps (Hot CFL)
- Cathode fluorescent lamps (Cold CFL)
- Incandescent light bulbs
But it’s not just the type of backlighting that’s important. The arrangement of the lights matters too. This is because the lighting arrangement and distribution determine how light is directed into the color filters and other critical layers of the screen. Two of the leading options are edge-lit and full-array.
Let’s draw an in-depth comparison of edge-lit and full-array backlighting to help you evaluate which technology is best for your viewing needs.
What is Edge-Lit?
Edge-lit screen backlighting is used to backlight an LED screen using LEDs to line the edges of the screen. Manufacturers place the LEDs along the top and bottom of the screen or right around the perimeter. A stiff piece of opaque plastic called a diffuser can then distribute the light across the screen.
Edge-lit screens differ from conventional LED screens as the backlighting does not originate directly behind the screen. It, therefore, has a more muted effect and the potential to introduce greater contrast into the images that are displayed.
Edge-Lit Screens Provide Focused Lighting
Edge-lit screens have more backlighting control than a basic uniform backlight, as individual LEDs can be brightened or dimmed to create focused backlighting in harmony with the screened content. Edge-lit LCD screen light achieves this by:
- The creation of up to 12 dimming zones made up of vertical bands that are created by brightening or dimming LED at the top or bottom edge of the screen.
- Independent dimming of top and bottom edge LEDs to create a greater number of targeted dimming zones.
Edge-lit dimming is generalized and diffused. This limits high dynamic range imaging and creates phenomena like haloing because of unwanted illumination of certain parts of the screen.
What is Full-Array?
Full-array, or full-array with local dimming (FALD), is an alternative backlighting technology that uses numerous individual LEDs distributed across the back of the screen. It is a newer and more refined backlighting technology when compared to an edge-lit screen.
The use of LEDs that are distributed across the screen area means that manufacturers can break the backlighting up into multiple localized dimming zones. Each zone can be individually brightened or dimmed to create an illuminated color that is in harmony with the displayed images. In particular, dark sections of the screen are more distinct, avoiding elevated black levels.
This local, more dynamic backlighting produces deeper colors and richer images because of the fine control of the backlighting. It enhances the display of HDR content and minimizes blooms or haloing. This is because FALD provides greater contrast than other forms of backlighting. This vivid display technology is now adopted by LCD/LED screens across all price points, though the more expensive screens have a greater number of dimming zones and match the images more precisely.
Edge-Lit vs. Full-Array: A Side-by-Side Comparison
| Edge-Lit | Full Array | |
| What is it? | A backlight panel arrangement | A backlight panel arrangement |
| Primary Use | Lighting for an LED-backlit LCD screen | Lighting for an LED-backlit LCD screen |
| Conceived | 1980s | 2000s |
| Initial Release | Late 1990s | 2012 |
| Technical Committee | Samsung | Sony, LG, Samsung |
| Influential Developers | Samsung | Sony, LG, Samsung |
| Open Format | Yes | Yes |
| Technologies Influenced | Televisions, desktops, monitors, laptops | Televisions, monitors, laptops |
©Ruslan Ivantsov/Shutterstock.com
The Differences Between Edge-Lit and Full-Array
Edge-lit and FALD provide the illumination necessary to view images displayed on an LCD screen. However, these two types of backlighting differ significantly in the arrangement of their LEDs, the degree of contrast they provide, and their ability to support HDR imaging.
Edge-lit screens have their backlighting around the edges of the screen, while Full Array screens have LEDs across the back of the screen, which can be illuminated in several localized zones.
Edge-lit screens were one of the first-generation backlighting technologies. But the earliest screens were affected by hotspots, and the lighting achieved was eventually perceived as inadequate. However, as LED technology advanced and could provide more nuanced lighting effects, Edge-lighting was revisited by Samsung, who released a market-leading edge-lit LED television in 2009.
Full Array screens are much more sophisticated and use an array of LEDs to provide targeted illumination across an entire LCD panel. This more advanced technology achieves greater contrast than Edge-Lit screens across a wider range of viewing angles and depicts colors more accurately. This has led to FALD superseding edge-lit lighting.
Pros and Cons of Edge-Lit
| Pros | Cons |
| Affordable | No precision dimming |
| Compact, thin screen | Narrower viewing angle |
| Energy-efficient | Variable image quality |
| Can dim the screen in sections | Less contrast than full-array |
| Lightweight | Elevated black levels |
| Potential for screen burn-in | |
| Local dimming is less marked than full-array |
Pros and Cons of Full-Array
| Pros | Cons |
| Better picture quality | Greater power consumption |
| Better representation of HDR images | More expensive to buy and run |
| Increased contrast and true blacks | Potential for screen burn |
| Wider viewing angles | Can cause screen burn-in |
| More targeted illumination | A single failed LED can cause the entire backlight to fail |
Edge-Lit vs. Full-Array: 6 Must-Know Facts
- Just one LED can illuminate 1,400 pixels of an LCD screen.
- Samsung pioneered edge-lit technology, launching the world’s first edge-lit TV in 2009.
- There can be 1,500 LEDs in a backlighting array for a 1,080-pixel TV. These can illuminate over 2 million pixels.
- The localized dimming of FALD introduced an exceptional level of contrast.
- Full-array backlit screens can adapt the localized lighting to the content that is being displayed.
- Edge-lit backlighting can make dark or black areas of the screen appear gray.
Final Thoughts
Your choice of flat-screen backlighting can really affect the quality of your viewing experience. Edge-lit screens are a mature technology that is affordable and energy-efficient.
But, for a cutting-edge viewing experience, full-array LED backlighting provides more accurately rendered color with the contrast that high-definition images require.
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The image featured at the top of this post is ©Vasyl Shulga/Shutterstock.com.
