Displays panels have always been a hot topic for technology enthusiasts as they enable you to visualize whatever hot new technology that manufacturers have to display from stunning new cameras, great UI design and visually intensive games. Displays are integral to the smartphone, television and laptops, but they are needed elsewhere too.
While the delta between a feature phone and smartphone is more than just a large screen for something like a watch the screen is a big part of the smart chops. Likewise, many other appliances and gadgets are made smarter by merely adding a display to them- from refrigerators, microwaves and even washing machines!
But, you might have noticed that not every display looks the same- no we are not talking specifically about resolutions but the display itself. A smartphone display looks different from the one on your smart fitness band. Your e-book reader gives a different experience over what your iPad gives and this varies across the board. They differ because each application needs a different type of display panel and that is exactly what we will look at today.
LCD is short for Liquid Crystal Display and it is the dominant type of display panel in the market. Available from smartphones to televisions to monitors, LCD displays use liquid crystals and a backlight (cold cathode fluorescent lamps) to display the image. Given that you can easily make the LCD brighter with a brighter backlighting setup, LCD are popular on smartphones and easily touch 1000 nits on high-end smartphones like the LG G7 ThinQ.
Apart from brightness, LCD’s are also known for their accurate colour temperature and do not get affected by burn-in or any such issues that plague other types of display panels.
But LCD’s do have their drawbacks, as they are backlit making the display brighter makes the blacks go grey in colour thus reducing colour accuracy. Also due to the fact that the whole display panel is active, LCD displays need more power. But their lower costs compared to other technologies make them a great choice for smartphones and televisions.
LCD is an umbrella term given to panels that use backlighting and there are various other types of panels under LCD. These change minor things like the type of backlighting as listed below:
TN panels or Twisted Nematic panels were the first type of LCD panels and are still in use today due to their low-costs. TN panels are usually poor in colour accuracy (especially blacks) and viewing angles but have an excellent refresh rate like 120Hz and above. This makes them a common sight in gaming monitors that need this high refresh rate.
VA or Vertical Alignment offers better colour accuracy and viewing angles than the aforementioned TN panels but lose to them when it comes to refresh rate and response times. Also, they are priced much higher than TN panels but lower than IPS panels.
TFT or Thin Film Transistor uses an active matrix which means that each pixel is individually attached to a transistor and capacitor. This allows them to have a great contrast ratio while still being priced pretty low (below IPS panels). Drawbacks include average colour reproduction and viewing angles.
A variation of the TFT panel is the IGZO panel found on many Razer laptops and the Razer Phone. IGZO or Indium Gallium Zinc Oxide is a variation in the transistors used by TFT monitors and is not a different panel by itself. Because it is made of rare earth materials, IGZO transistors are very expensive but benefit in providing a display with amazing colour accuracy, excellent refresh rates (120 Hz on the Razer phone) and low power consumption.
IPS or In-Plane Switching is a panel type that's meant to improve over the TN, VA and TFT ones. Using a different orientation of the crystal array, IPS panels achieve a much wider viewing angle, superior colour accuracy and reproduction and better contrast ratios too. IPS panels with the lower power consumption are a reason why most smartphones even budget ones like the Redmi Note 6 Pro use them despite them being priced higher than TFT panels.
PLS or Plane to Line Switching panels are made by Samsung and are similar to IPS panels. Samsung claims PLS panels offer better viewing angles, a 10% increase in brightness, a 15% decrease in production costs, increased image quality, and allows for flexible panels over IPS.
LED or Light emitting diode panels are contrary to what most people think actually just LCD panels with an LED backlighting instead of the cold cathode fluorescent lamps used by LCDs. LED backlighting makes displays thinner, boosts brightness, improves the contrast ratio and reduces power consumption too. It is more expensive but worth the investment.
Basically all LCD televisions today are moving towards LED backlighting and this is where you get three different types of LED backlighting.
Direct-Lit: Have few LEDs placed behind the panels and are the cheapest type of backlighting. Due to the few LEDs, they do not support local dimming (illuminating part of the LEDs)
Edge Lit: Have LEDs at the edges which are more in number than Direct-lit but still give an uneven backlighting
Full Array: Full Array backlighting is similar to direct-lit but have more LEDs and allow for better control of individual LEDs (local dimming) allows for even brightness and better dark scenes.
QLED televisions are derivatives of the LED technology and use Quantum dots (tiny phosphorescent crystals) that allow producing a much more natural white colour when compared to LEDs. They even allow a much deeper black and truer colours as well. Samsung is betting big on the QLED technologies for televisions moving ahead.
Demoed at CES 2019, the ULED XD technology from Hisense aims to improve the black levels of LCD panels while removing the Halo effect common on LCD’s. They achieve this by stacking two LCD panels- one grayscale module and one coloured 4K module.
This allows the panel to produce a much deeper black with improved local dimming, a high peak brightness (nearly 2900nits) and excellent contrast ratio.
The market currently is filled with a lot of panels that are basically variations of the LCD panel, there is one technology that differs- OLED. OLED aims to improve in areas where LCD televisions lack like refresh rates, response times, black levels etc.
Unlike LCD panels, OLED or Organic Light-Emitting Diode panels do not need backlighting instead they use organic material to pass light and individual pixels simply turn off when they have to display the colour black. This is one reason why the can delivery excellent black levels and consume less power when displaying black or dark colours.
OLED panels are no doubt more expensive than LCD but they also have brought improvements like a higher refresh rate support, thinner displays and ability to make the display flexible. There are drawbacks too in the form of screen burn-in and degradation over time.
AMOLED or Active Matrix Organic Light-Emitting Diode panels are found on phones from Samsung, OnePlus, Xiaomi and Motorola and are an advancement over the OLED technology. The AMOLED panel uses an Active Matrix of OLED on a TFT panel. This allows for a higher control over the flow of current to the pixels.
While they have their benefits similar to an OLED panel, AMOLED tends to consume more power when displaying lighter colours.
Super AMOLED is a variation of the AMOLED panels by Samsung and is found on Samsung’s high-end Galaxy S series and the Note series. Super AMOLED panels differ from regular AMOLED by integrating the touch response layer into the display thus making the whole assembly much slimmer.
Micro-LED panels are the future of OLED panels and are yet to reach their full potential in the market. These panels are slimmer than OLED panels and work similar to OLEDs but use inorganic semiconductors (Gallium-Nitrite).
Micro-LED panels show major improvements in power efficiency taking about half the power at a set brightness over an OLED panel. Add to that the smaller physical size of the diodes which allow you to pack in more pixels in a smaller form factor. In fact, a 4K smartwatch is also possible with micro-LEDs- not that we need a 4K smartwatch!
Verdict and Summary
When it comes to displays there are a lot of specifications, standards and technologies that come to the picture making the decision very complicated. But in our four-part series of Display standards and technologies we have covered resolutions, HDR, refresh rate and this time we took a look at display panel types.
When it comes to display panels you have to understand that there is no “one panel fits all” concept. While some are good for gaming, others are better at colour accuracy. Ultimately it is up to you to decide on what is good for you.
Do not merely pick a phone, television or monitor based on the panel type, rather look through reviews and tests conducted on the panel to show its colour accuracy, brightness, contrast ratio, viewing angles and other parameters.
Also, keep watching this space for more articles that help clear all your doubts and confusion on the various technical standards around us.