This year, Mini LED and OLED displays have reached a breakout period, with Mini LED starting to transition from monitors to mobile devices, and OLED screens gradually becoming more common in mid to high-end displays. When users choose related products at this stage, they also face the dilemma of different screens/panels. Looking at the parameters, they all seem “good,” and it is challenging to determine which product is suitable based solely on the promotional content on the product pages. Today, let’s briefly discuss several common types of screens available on the market and their respective advantages and disadvantages.
LCD: The Most Mainstream Display Technology
Even with the introduction of newer Mini LED and OLED technologies, LCD remains the most mainstream display technology today. You can see it in everything from small smartwatches to 100-inch televisions. One of the core technologies of LCD is the use of liquid crystals, which easily change shape under the influence of electric and magnetic fields. LCD utilizes this property to control the colors of pixel points, thereby forming images through the on and off of sub-RGB subpixels. However, the liquid crystal layer itself does not emit light; it requires a backlight layer to provide illumination. Therefore, the two most critical components of an LCD screen are the backlight layer and the liquid crystal layer, and technical improvements to LCD screens are almost exclusively focused on these two components.
The early improvement of LCD was to replace the CCFL cold cathode fluorescent lamp used as the backlight with white LED beads, which have advantages in cost, heat, and lifespan, also known as WLED backlight. However, as WLED often uses blue light as the primary color, the yellow phosphor that neutralizes blue light experiences wear and failure over long-term use, leading to color gamut and color accuracy issues in displays using traditional WLED backlights. Some professional wide color gamut LCD displays also use GB-r LED or RGB LED backlights, which are derived from WLED backlight technology.
From CCFL cold cathode fluorescent lamps to side-lit LED backlights
Based on the arrangement of liquid crystal molecules in the liquid crystal layer, we have the TN, IPS, and VA panels we are now familiar with. The TN panel, which was introduced first, has a relatively small viewing angle, low contrast, and average color performance, but its advantages include low cost and fast response time, which is still widely used in low-end laptops and gaming monitors. IPS, as an improved technology over TN, has good color performance at wide viewing angles. In recent years, Fast IPS and Nano IPS have greatly improved response time and color performance. VA panels integrate characteristics of both TN and IPS technologies, offering a balanced performance, with the biggest advantage being suitability for large and curved screens.
LCD has developed into a mature display technology, with the intersection of backlight technology and liquid crystal technology forming a wide variety of products at relatively low costs. The main disadvantage of LCD is that the liquid crystal layer is always in an excited state when turned on, which means it cannot be completely turned off, leading to some light passing through the liquid crystal layer even when displaying black, resulting in insufficient contrast, especially evident in screens without local dimming.
The poor black display performance of traditional side-lit backlighting
OLED: The Imperfect “Strongest King”
OLED, also known as organic light-emitting semiconductor, does not rely on a backlight module; each subpixel emits its own light. For this reason, VESA has launched a new series of DisplayHDR True Black standards specifically for OLED and future Micro LED, adding a standard with a maximum black level brightness of 0.0005 nits to achieve the effect of “true black.” Additionally, the self-emitting characteristics also make the screen more power-efficient, reducing the power consumption burden on mobile devices. Moreover, due to differences in driving methods, OLED panels also perform excellently in response delay, easily achieving response times below 1ms, which is currently difficult for LCD panels to achieve.
OLED has a simpler structure and superior display effects
Similar to LCD, the OLED screens used in products like mobile phones, monitors, and computers do not adopt a unified technical route. The mainstream types of OLED include OLED, W-OLED, and QD-OLED (LTPS, LTPO, IGZO belong to substrate materials that can be applied to different OLED panels). The OLED (AMOLED) used in mobile phones is quite close to the OLED technology we are familiar with, with RGB primary color pixels emitting light independently. However, due to material-related factors, the blue subpixel has the shortest lifespan, leading to the later Super AMOLED, which arranged the three primary color subpixels in a diamond shape, greatly improving the green screen phenomenon by sharing the green subpixel.
Arrangement of pixels in LCD and Super AMOLED
While changing the pixel arrangement in OLED has solved the green screen problem, it has caused resolution loss issues. Increasing the resolution to ensure PPI is not suitable for large display devices or televisions that require point-to-point display. Therefore, most OLED televisions use W-OLED, which adds a white subpixel in addition to RGB, enhancing the brightness of the display, but the color performance of W-OLED may decline at high brightness. Notably, monitors like the Philips 27E1N8900, which features a JOLED printed RGB OLED panel, use a quasi-RGB arrangement that resolves the text display resolution issues of traditional OLEDs, but it is currently only applied to small screen devices like mobile phones and monitors.
To address the color decay issue of W-OLED televisions at high brightness, the QD-OLED technology has emerged. QD-OLED integrates the technical characteristics of quantum dots and OLED, using photoluminescent quantum dot materials to replace polarizers, allowing OLED and quantum dots to work together to display colors. This has the advantage of maintaining the original fast response characteristics of OLED while significantly improving brightness and color performance. It is worth noting that quantum dots can also be used as backlight technology in LCDs and can even be combined with Mini LED technology, such as the Philips 27B1U7903, which features a QD-MiniLED panel.
Despite its impressive capabilities, OLED also has drawbacks. Due to the use of organic materials in OLED screens, displaying the same content for an extended period can accelerate screen aging and leave burn-in marks. Manufacturers are currently employing various methods to alleviate the “burn-in” problem, such as pixel shifting and brightness control (which also limits the brightness performance of OLED screens), but in terms of lifespan, OLED screens still do not match LCD screens. Another disadvantage of OLED screens is eye strain, as PWM dimming methods can easily cause eye fatigue, and if simulating DC dimming at low brightness, it can lead to poor color uniformity, commonly referred to as “rag screen.”
Mini LED: Miniaturized LED Backlight Technology
The disadvantage of LCD is its inability to produce “true black,” and traditional LCD screens often exhibit uneven backlighting and light leakage. In response to this, technologies such as side-lit local dimming and direct full-array backlighting (checkerboard backlighting) have emerged, with Mini LED backlighting being seen as a complete form of direct full-array backlighting. Therefore, Mini LED should actually be referred to as LCD screens utilizing Mini LED backlighting. Mini LED technology allows LED beads to be made very small, resulting in more precise light control.
Mini LED backlighting can also directly use RGB three-color LED modules, achieving higher color gamut coverage and significantly enhancing the color performance of the panel. The number of backlight zones in monitor products has also increased significantly. For example, the Philips 27B1U7903 display, which uses Mini LED backlighting, has 2304 backlight zones, with color gamut coverage of 99% sRGB, 99% AdobeRGB, and 97% DCI-P3, and a peak brightness of up to 1400 nits.
With the increase in video content creation, the demand for HDR video production has also gradually increased. Monitors used for producing HDR videos must meet at least the HDR1000 minimum standard. Compared to the expensive OLED monitors, Mini LED monitors are only 60% to 80% of the price of OLED, making them a relatively low-cost solution. Currently, the top Mini LED screens can achieve over 4000 dimming zones, and even the iPad Pro 12.9 has 2500 dimming zones, with finer zones providing outstanding dark field and HDR video performance.
Mini LED has far superior contrast and brightness advantages over LCD, but it still belongs to backlight technology and cannot avoid the “halo effect.” This is because the number of dimming zones is still not fine enough, leading to the backlight illuminating more than what the actual panel displays, resulting in a halo of white light around the displayed image. Due to the presence of the backlight layer and liquid crystal layer, Mini LED does not have a size advantage, and the heat generated by the large number of LED beads is also considerable, prompting some Mini LED displays to be equipped with cooling systems.
To avoid confusion when discussing quantum dot technology mentioned in the previous section about QD-OLED, we have created two tables based on the structures of LCD, Mini LED, QD-OLED, and the respective advantages and disadvantages of traditional LCD, OLED, Mini LED, and Micro OLED for your reference.
Red indicates leading, gray indicates lagging
Conclusion: Micro LED is the Star of Tomorrow, Choosing Mini LED/OLED is Also Good
Today, we summarized several common types of screens available on the market (LCD, Mini LED, OLED) and their implementation technologies and pros and cons. The best display technology is still OLED, while Mini LED has the opportunity to share the market with OLED due to its price advantages. The Micro LED, which combines all the advantages of OLED and LCD, is the future trend of display development; you can think of it as using micron-level backlighting to directly replace the liquid crystal layer for display, just like Mini LED. However, it may take time before Micro LED is commercially available and even longer for widespread adoption. It is worth noting that Mini LED and QLED share a lineage with Micro LED in critical packaging and mass transfer technologies (mainly limited by yield and cost), so those who can wait might consider trying high-end Mini LED and OLED products while waiting for the arrival of Micro LED.
Editor: Xiong Le
Recommended Previous Content
Do you really not need to consider powerline adapters anymore?
A socket that can be plugged and unplugged with one hand!
Ryzen 5 5600 first review
·END·