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The development of smartphones in recent years is evident to everyone, and the screen, as the “face” of the phone, is something users spend hours looking at every day. Over the years, smartphone screens have evolved continuously, with larger sizes, higher resolutions, and increased screen-to-body ratios, while the color performance has also improved significantly. High-end smartphones have widely adopted OLED screens, marking OLED as the mainstream technology. This article outlines the history of smartphone screens:
Classification of Screens: Simple Yet Significant
First, to discuss the evolution of smartphone screens, it is important to note that there are currently two main types of screen materials on the market: LCD and OLED. In the early years of smartphone development, LCD became the mainstream material due to its high color reproduction, mature manufacturing process, and high brightness. LCD stands for “Liquid Crystal Display,” a substance that is between solid and liquid. Since it cannot emit light by itself, it requires an additional light source, such as LED, thus needing a backlight. Technologies like TFT, IPS, and SLCD are all based on LCD screens.
In recent years, OLED screens have become more prevalent. OLED stands for Organic Light Emitting Diode, and unlike LCD, OLED screens emit light on their own, eliminating the need for an external light source. This allows OLED screens to be thinner while providing wide viewing angles, low power consumption, high contrast, fast response rates, and high color saturation, making them the gradually dominant screen material in the market.
Development of LCD Screens: A Choice for Most Phones
Regular TFT
A few years ago, TFT screens were the most widely used on the market. TFT stands for Thin Film Transistor, which means it is a type of thin-film field-effect transistor. This screen has good color saturation, reproduction capability, and contrast, with advantages like a mature manufacturing process, high yield, and low cost. Representative models include Motorola Defy+ and Sony LT22i. However, the downside of TFT screens is that they consume more power and do not provide a high-quality touch experience or sensitivity when used on touchscreen devices, gradually failing to meet user demands.
TFT screen of Sony LT22i
IPS Screen
As users’ demands for screen quality increased, TFT screens could not meet their needs, leading to the emergence of IPS technology. IPS screens, also known as “Super TFT,” incorporate IPS technology into TFT screens. Although they are essentially still TFT screens, IPS screens have a wider viewing angle, more accurate color reproduction, no water ripple during touch, and are energy-efficient. Representative models include iPhone 4 and iPhone 4s.
IPS screen of iPhone 4
SLCD
SLCD stands for Splice Liquid Crystal Display, a high-end derivative of LCD screens primarily used by HTC. It tends to have warm color tones and features high contrast and color reproduction, making it easier on the eyes. Notably, SLCD screens have a lifespan of up to 50,000 hours, so users need not worry about longevity. Representative models include HTC G11, HTC G14, and HTC G18.
SLCD screen of HTC One X
Due to the excellent market performance of SLCD, multiple generations of products have been developed (currently, the fifth generation known as Super LCD 5 exists), featuring outstanding transparency and saturation control, gaining high recognition from users. Representative models include HTC U Ultra.
ASV
When discussing branches of LCD screens, one cannot overlook ASV technology, developed by Japan’s Sharp Corporation. This technology reduces the spacing between liquid crystal panel particles, increases the light aperture on the liquid crystal particles, improves image quality, and adjusts the arrangement of liquid crystal particles to reduce screen reflection, enhancing brightness, viewing angles, and contrast. Unfortunately, this technology is rarely licensed to other manufacturers, except for early models like Meizu MX and Xiaomi Phone 1.
Meizu MX and Xiaomi Phone 1 with ASV screens
NOVA
In display technology, LG has introduced NOVA technology, which enhances the brightness of IPS screens, allowing them to reach a maximum brightness of 700 nits, while maintaining accurate black and white color display even in bright conditions, providing a good reading experience outdoors. Most importantly, NOVA screens can reduce power consumption by 50% compared to IPS screens. Representative models include LG P970.
LG P970 with NOVA screen
OLED Screens: From Criticism to Comeback
OLED screens are not exclusive to Samsung; the OLED screen on the Redmi Pro comes from BOE and Huaguang, while the curved OLED screen on the Xiaomi Note 2 comes from LG. However, most OLED screens on smartphones are sourced from Samsung, which has the most mature OLED technology. Therefore, we will introduce Samsung’s AMOLED screens.
Early AMOLED
Samsung was one of the first manufacturers to research OLED screens, with over ten years of development. AMOLED is derived from OLED, and compared to traditional TFT screens, AMOLED features fast response times, higher contrast, and wider viewing angles. Its touch performance, both in accuracy and response speed, surpasses that of ordinary screens, and it performs excellently in power consumption. However, the initial yield rate was low, with early AMOLED screens used in high-end models like Nokia N8 and Nokia N86.
Nokia N86 with early AMOLED screen
Super AMOLED
As the name suggests, this is the second generation of AMOLED screens. Super AMOLED screens outperform AMOLED in terms of detail, reflectivity, power-saving capabilities, and response speed. Their high color saturation and vibrant display have made them a staple in Samsung’s products.
Super AMOLED screen on Samsung Note 5
Notably, the Diamond arrangement (diamond-shaped) pixel layout used in mainstream models is derived from the Pentile arrangement, where the former is arranged in a diamond shape in a 1:1:2 ratio, while the latter arranges RGBG in parallel. The former utilizes subpixels more effectively, resulting in reduced jaggedness in screen details compared to the previous Pentile layout.
Flexible OLED Screens and COP Packaging
In fact, this is a process to solve the placement of screen wiring. In traditional processes, phone wiring requires space for installation, leading to the necessity of leaving enough space at the bottom of the phone (the chin), which is one reason why the screen-to-body ratio cannot be higher;
With COP technology, phone wiring can be folded to the back of the screen and connected to the motherboard, allowing for a smaller bottom frame, which is how the iPhone X achieved its ultra-small “chin.”
However, COP technology has drawbacks: it is costly and can only be applied to flexible OLED screens. This means that phones using COP technology are generally more expensive and can only utilize OLED screens, leaving LCD screens out of the equation.
COP packaging technology on iPhone X
A New Path for Smartphone Screens: Will QLED Become a Trend?
With the continuous development of screens, a new QLED screen technology has emerged. QLED is a new type of light-emitting technology, namely Quantum Dot Light Emitting Diode. Similar to OLED, QLED also has self-emitting characteristics, but while OLED’s self-emitting body is organic diodes, QLED’s self-emitting body is quantum dots.
QLED Quantum Dots
However, QLED is still in the research and development stage, and QLED screen technology is currently mainly used in large screens like televisions. The quantum dot technology on the market is primarily an optimization of the backlight source based on LCD technology, known as photoluminescence, and has not yet achieved self-emitting characteristics. Therefore, current QLED screens resemble a hybrid of LCD and OLED. It seems that there are still many technical challenges to overcome in QLED technology.
Conclusion:
It must be said that after so many years of development, screen technology has significantly improved in display quality. With the continuous rise in user demands, manufacturers are exploring new avenues in screen technology. Based on recent market trends, OLED screens are gaining momentum. As domestic screen manufacturers ramp up their efforts in the OLED field, OLED screens are likely to become even more popular in the coming years. However, this does not mean that LCD screens will fade into history; after all, LCD screens are here to stay.
At the same time, the emergence of QLED brings infinite possibilities to the future of smartphone screens. In short, everyone is competing over this small screen, and new technologies will continue to emerge. Let’s wait and see!
– Adapted from PC Online
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