Direct LED and Edge LED are ways of placing the LED panel of matrix backlight. They differ in the location of LED elements. In the first case, the LED panel is directly behind the forming image, in the second – on its edges (actually – on the side of it).
Both of these technologies are used in televisions and monitors. And the difference between them lies not only in the design, but also in some operational features.
To understand what is better to choose, let’s look at these types in details.
How is the Direct LED backlight
The screen, equipped with a Direct LED, is built “like a sandwich”, that is, it consists of several main layers. The first, most posterior, is the LEDs themselves. They can be located quite “often” or “rarely” depending on the TV model used.
The second layer is the image panel itself. It’s made with a translucent base so the light from the LED elements can pass through it.
And the third is a protective plastic film or glass.
The main advantage of this technology is the possibility of local dimming. In this mode, some of the LEDs are turned off, creating a richer black color. The dynamic contrast of the display becomes huge, up to 1000000:1, or – in some models of monitors – even more. On TVs with LED backlighting and local dimming support it is very convenient and pleasant to work with dark backgrounds or watch movies with a lot of scenes in the dark.
However, not all backlit televisions and displays have local dimming technology. It is recommended to check before buying with the seller.
High contrast, especially dynamic contrast;
Uniformity of brightness and lack of “lit” areas.
High power consumption – a lot of “current” is spent directly by LEDs;
The great thickness of the TV or monitor itself is that the matrix itself is quite thick, so it needs to be somehow cooled by heat sinks;
Noticeable input lag, which can be 100-150 ms;
Input lag is due to the fact that the TV needs to build a “picture” map before outputting the image, taking into account the location of the LED elements. This consumes time. And the cheaper the TV or display, the more noticeable its input lag, because a high-performance processor for processing is not cheap.
How the Edge LED backlighting works
Edge LED is arranged a little easier. The panel of pixels that create the image is on a reflective white or silver substrate, and the panel of LEDs is located on its sides. You can significantly reduce the thickness of your TV or display.
The main disadvantage of the side backlight is uneven brightness distribution and the appearance of “highlights. They can be seen against both light and dark backgrounds. Shadows “gather” at the edges and corners of the screen – where the LEDs are placed directly.
So, in dark scenes, the “picture” in the corner of the TV screen will seem dark gray. And with light, the saturation at the edges will be much higher than in the center.
Small thickness of the matrix – and, as a consequence, the TV itself;
Small input lag, which can be less than 10 ms;
Sufficiently high levels of brightness and contrast (especially static).
Uneven brightness distribution in some models;
Appearance of noticeable “highlights” at edges and corners of screen in some devices.
Despite possible “glare”, minimal input lag is practically a “killer feature” for gaming monitors. This is especially appealing to gamers who in dynamic competitions will see every object on the map.
In addition, TVs with side mounted LED elements are really super thin. In 2017-2018, there were several models of home TVs with a thickness of about 5 cm or less, including those with a separately mounted computing unit. And these TVs, which are thinner than the picture, are equipped with such a matrix.
Which is better?
There is no definite answer to this question. And it’s not just the differences between the technologies. Often the quality of the sensor itself varies from manufacturer to manufacturer.
For example, the author of this material at home TV with Direct LED. However, the technology of local dimming is not implemented in this model, so in the evenings the screen turns into a searchlight that lights up the whole room at any setting.
Direct LED is good only if it is complemented by local dimming. This helps increase contrast (dynamic and static), and provides more cinematic scenes.
Edge LED is good if the developer of the screen himself took care of the uniformity of luminescence. Otherwise, “glitches” in the corners will become annoying.
So if you have to choose between these two types, it is better to come to the store and see for yourself which type of TV or monitor you like better.