What is a TV panel?

Without going into technical depths, we can say that the panel is the main element of the screen, which is directly responsible for the image quality. Contrast and brightness indicators, color gamut and color reproduction in general, even viewing angles depend on it.

In modern TVs, the panel is rather thin, but multi-layered. The main element of liquid crystal displays (LCD) is a layer of liquid crystals (hence the name) with control electrodes. In addition, a light source is needed, the role of which is usually assigned to LED backlight, hence the modern designation - LED TVs. The panel also has polarizing films and a light filter (one or more).

This is what a modern LED panel looks like in layers: 1 - backlight; 2 - polarizer; 3 - liquid crystals; 4 - light filter; 5 - polarizer.

Simplified, the scheme for displaying an image on such a panel looks like this:

  • light from the backlight is supplied to the liquid crystal layer;
  • crystals are controlled by electrodes;
  • if the crystal is in the closed position, then the light does not pass;
  • if the crystal is open, then the light goes further, and the light filter paints it in the desired color - red, green or blue;
  • as a result of mixing colors, the desired picture is formed on the screen.

What panels are used in TVs today?

Since technology evolves, panels are different. Even within the terms of the LED technology described above, there are plenty of differences. So, the geometry (arrangement) of liquid crystals on the panel can be different. According to this criterion, there are three main types of panels - TN + Film, IPS and VA. And the image displayed by them, even other things being equal, has huge differences.

Even today, different types of backlights are used, including edge, back, full and more. We will talk about these and other varieties in more detail.

Innovations also affected the filters of the panels, thanks to which, for example, QLED TVs appeared. And in addition to the marketing component, this innovation directly affected the quality of the picture.

Also, panels without backlight are becoming more and more popular. There is both: one well-proven technology - OLED, and very promising, but not yet widely used - MicroLED. In these two variants, the panel is based on self-luminous elements - organic or inorganic light-emitting diodes.

And then there are various marketing names, including NanoCell, QNED and Neo QLED. We will also talk about these technologies, although in fact they all combine LCD TVs with LED backlighting.

We will talk about modern panels and their various technical features as image quality improves and prices rise. There will be three segments - entry level, middle and upper class.

Entry level - various LED TVs with edge or back lighting

In modern LCD TVs, one of two types of panels is most often used - IPS or VA, as well as their modifications, for example, PLS or MVA.

Previously, TN (TN + Film) was also quite popular, but now it is obsolete and almost never used, with the exception of "ultra-low-cost" TVs, entry-level office or gaming monitors. This sensor is cheap and can offer fast response times, but contrast, viewing angles, and color gamut are questionable. Therefore, we will not dwell on it in detail.

The fundamental difference between IPS and VA panels is in the structure of the layer with liquid crystals and the principles of their alignment.

IPS and VA panel pixel structure.

Different geometry and features of work directly affect the image quality.

The vertical arrangement of crystals in the VA panel causes them to be located closer to each other. As a result, when closed, they effectively block light coming from the backlight, increase image contrast (above 3000:1), and produce deeper, more smooth black colours. Of the TOP brands, such screens are most often found in Samsung TVs, but they are also actively used by other manufacturers - Sony, Philips, TCL, etc.

IPS panel crystals, due to horizontal alignment, let in more light, so the image contrast is reduced (for them, a figure of 1000: 1 is considered more or less normal), and black is more like dark gray. On the other hand, such a pixel structure contributes to an increase in viewing angles. And among inexpensive solutions, ceteris paribus, IPS often wins in terms of color gamut and natural color reproduction. These panels are used in LG TVs.

In addition to the type of panel itself, the quality of the image is also affected by the applied backlight. In the low cost segment of TVs, either side Edge LED or rear Direct LED is used. The first is located around the perimeter of the screen or only on the sides to the left and right, but is supplemented with a special reflector to improve the smoothness of illumination, and the second occupies the entire back surface.

Differences between simple types of LED backlight.

Edge LED is more often used with VA panels, since even with not the most smooth illumination, the contrast remains high, and there are no backlights in dark scenes. Direct LED, which is more smooth, is more actively used with IPS to somehow smooth out the problem of heterogeneity and insufficient black depth. Of course, there are enough exceptions to this rule, but if the combination of VA + Direct LED can improve picture quality, then IPS + Edge LED only exacerbates the problem of poor black colours and increases the likelihood of the Glow effect.

Direct LED TVs

Which panel to choose with a limited low-cost? Everything depends on your tasks. For example, for a kitchen where TV is not watched in the dark, and the viewer is often not directly in front of the screen, good visibility is important and a TV with IPS and Direct LED backlight is better. The same combination is preferable for collective viewing, that is, rooms with a large number of seats. But for movie viewing, especially in a room with subdued light, VA-panel TVs are better.

Middle class - LED with local dimming or QLED

Mid-range TVs today are also based on either VA or IPS panels. Why is the price higher? The image quality increases. One way to do this is with more advanced backlights such as Full-Array Local Dimming or FALD

This is a further development of Direct LED, meaning the LEDs are also evenly spaced across the back of the screen. And to increase the contrast of the image and display more natural black colors, a local dimming feature has been implemented. How does it work?

When you need to display a dark scene, a conventional LED TV does not turn off the backlight, just the panel crystals take a closed position and try not to let it through. In practice, in the same IPS screens, this results in a dark gray picture. To eliminate this issue, a local dimming feature was created. It dims or turns off the backlight in the desired areas of the screen. As a result, dark scenes look more natural, and the rest of the areas do not lose brightness, that is, the overall contrast of the image is increased.

How local dimming works.

But local dimming differs in the quality of implementation in different TVs. And often this feature does not work perfectly. Color smoothness may suffer, shadow detail may be reduced, ghosting or other artifacts may appear around bright objects.

Also, the real benefit of this feature directly depends on the number of local dimming areas. The more of them, the higher the contrast and smoothness of color, the lower the likelihood of image issues. But the middle price segment still has compromises.

Also, the image quality can be improved by using quantum dot technology. Today it is associated with QLED TVs offered by Samsung. But similar models are produced by other brands, including Hisense and Xiaomi. In addition, similar technology is provided by LG - it's called NanoCell, but it did not have such a high marketing success.

Is it correct to call QLED a separate type of panel? Of course not. These are good old LCD TVs based on IPS or VA panels. They have the same LED lights. And the main difference is in the use of a light filter with quantum dots. It is located just between the backlight and the liquid crystal layer.

The main distinguishing feature of QLED is the presence of a layer of quantum dots. In the diagram: 1 - backlight; 2 - QDEF; 3 - polarizer;
4 - liquid crystals; 5 - light filter; 6 - polarizer.

Quantum dots really improve image quality, they expand the color gamut, provide a brighter, richer and more saturated picture, which is important, for example, when viewing HDR content. The best result in the middle class is provided by a tandem of VA and QLED filter.

Successful variations of IPS and quantum dots are also available, but already in a higher price segment, like LG 65QNED90, also an even more advanced type of backlight is used there (we will talk about it a bit later).

QLED TVs

Which panel to choose in the middle price segment? The recommendation is the same as for entry level TVs, but adjusted for technology. If wide viewing angles are a priority, then an IPS panel is recommended, and preferably with FALD backlighting or any similar technology that supports local dimming. If the TV is chosen primarily for watching movies and HDR video, then QLED models based on a VA panel will suit you best.

Premium class - OLED, flagship QLED with Mini LED, new technologies

In the highest price category, LED TVs are also presented. Mostly these are top-end QLED models, that is, TVs based on VA or IPS panels with an additional quantum dot filter.

The preferred choice among such TVs will be solutions with a new type of backlight - Mini LED. It is sometimes even called the last round of the evolution of liquid crystal panels. The key feature of such a backlight is already in the name - smaller diodes are used here. Their total number has increased greatly, which in turn allows you to get more local dimming areas, which means increased contrast, better color reproduction and better quality of HDR content.

What are the components of a premium LED TV today.

By the way, Samsung often combines Mini LED technology in its flagship LED TVs with the Viewing Angle Layer feature, which partly eliminates the problem of narrow viewing angles in VA panels. This combination, for example, is offered in the QE-65QN90A TV.

Also we have to mention the marketing tricks briefly: Samsung has a combination of QLED and Mini LED called Neo QLED, and LG has a tandem of NanoCell (the same quantum dots) and mini LEDs - QNED. Thanks to all the gods that at least Sony did not introduce an additional confusing term :)

In the premium segment, of course, OLED panels cannot be ignored. This is a fundamentally different technology that holds the leading position in terms of image quality today.

Compared to conventional liquid crystal models, OLED TVs are notable for the lack of backlighting. The light source is self-luminous diodes - pixels. Literally any of the 8 million dots (in a 4K panel) can be turned off to display perfect black colours without blurring or haloing around bright objects in the frame. The picture on the OLED panel has a contrast ratio tending to infinity, excellent depth and black colour smoothness, a wide color gamut, excellent viewing angles (usually even wider than IPS).

The main differences between OLED and LED panels. Features of LED/LCD: complex structure, illumination by a lamp or LED, lighting unit - pixel. Features of OLED: simple structure, light directly from LED, lighting unit is pixel.

Not very high peak brightness is one of the shortcomings of the image in such displays. But on top of deep dark shades, even a not very bright picture looks convincing, so HDR content looks stunning. And the downside of OLED is the risk of pixel burn-in when displaying static content. It is unlikely that it will be a problem if you pause the video and leave for 10 minutes (especially since users are offered various panel recovery features), but such TVs are not recommended for the role of a PC monitor.

Interestingly, until recently, the picture on most OLED TVs was roughly the same. That is, the difference between the more affordable LG OLED65B1 and the expensive Sony XR-65A90J was primarily in additional features. The situation changed somewhat in 2022, when new OLED models debuted on the market. Their panel is called QD-OLED.

Modification of the OLED panel with the addition of a layer of quantum dots.

In fact, this is a technology that combines the capabilities of OLED and QLED. So, almost the same panel on organic light-emitting diodes is used here, but the diodes themselves are blue (and for ordinary OLEDs they are white). There is no backlight, but a layer of quantum dots has been added. The main change was an increase in peak brightness and an exceptionally wide color gamut (100+% DCI-P3). But the problem of burn-in is also typical for these models, and the price is higher than that of the “classic” OLEDs.

MicroLED technology may soon impose competition on OLED panels in the premium segment. It also does not need additional illumination, and instead of organic diodes, inorganic diodes are used - based on indium gallium nitride. To all the advantages of OLED, an even smaller panel thickness and increased reliability are added here. However, the manufacturing technology of such panels remains expensive and complex. Accordingly, they are not intended for the mass consumer. In 2022, it is planned to produce about 1,000 of these panels for commercial purposes. For comparison, the current annual production of OLED reaches 10 million units, and LED - 250 million units.

Which panel to choose if you are not short on a low-cost? Now it is worth taking a TV with an OLED screen. It can be either a version with white organic LEDs, which have already proven themselves in the market, or relatively new QD-OLED TVs, but their range is still very small. It is advisable to abandon OLED if you plan to use the TV as a PC monitor or are very afraid of the problem of pixel burn-in. In this case, it is worth considering top-end QLED models with miniLED backlighting.

If (when) microLED panels come to the mass market, then, probably, the additional fee for them will be justified by a longer working life. But so far this is mostly just speculation.

Samsung has already introduced its microLED TVs, but not yet for a mass audience.

A brief guide on technologies and marketing terms as a conclusion:

  • VA and IPS are two popular panels used in LCD TVs. These panels must be backlit. IPS wins in visibility, VA in image contrast.
  • QLED is a technology for applying a layer of quantum dots in the production of panels. These are all the same LED TVs (that is, with backlighting) but with an additional filter that increases color saturation.
  • OLED is a panel based on organic self-luminous diodes. Does not provide lighting. Provides excellent contrast and deep black colours at excellent viewing angles. The only downside is the risk of pixel burn-in in a static picture, so an OLED TV is not the best choice as a PC monitor.
  • mini LED is one of the most advanced backlit types in LED TVs. Its main feature is a lot of small LEDs and the ability to increase local dimming areas from hundreds to thousands.
  • QD-OLED is a panel based on organic diodes with an additional light filter with quantum dots. It has all the advantages of OLED, increased peak brightness (important for playing HDR content), but the same burn-in risks.
  • microLED is a new promising type of panel. It is close to OLED, as it also does not have a backlight and has self-luminous elements. They are inorganic here, that is, the durability should be higher. But so far, microLED manufacturing technology is expensive and not mass-produced.