Why Did the iPhone Suddenly Switch from LCD to OLED Screens?

2017 marked the tenth anniversary of the iPhone’s birth, and Apple released three iPhones at once, two of which looked like traditional models, while the iPhone X, as the tenth anniversary edition, attracted the world’s attention as soon as it was unveiled

The large “notch”, extremely narrow bezels, especially with a starting price of $999, a sense of noble Apple aroma comes rushing at you

Apple said this is the biggest change since the iPhone’s birth, with an unprecedented appearance and innovative facial recognition, which will lead Apple into the next decade

Of course, my understanding of the next decade is not that the notch will dominate future iPhones, even though it did so in 2018. What Apple wants to convey is more like a hope for the future and an exploration of appearance and technology

Today we will talk about the OLED screen, which is often overlooked but considered a future technology

OLED is not a new technology; it appeared on the Nokia N85 back in 2008, but the resolution was only 320×240, while the iPhone at that time had a resolution of 480×320

However, I have not used this phone, but I bet you would think the first OLED phone was from Samsung, while Samsung’s first OLED screen was on the i7110, but both were Symbian systems

By 2010, Samsung began to focus on OLED and gave it a high-end name, Super AMOLED

The first product was the Galaxy S, the pioneer of the Galaxy series, and later Super AMOLED became the standard for Samsung’s flagship

Alright, let’s stop reminiscing for now. Why did Apple wait until 2017 to use OLED?

One important reason is that iPhones have always only adopted mature technologies. Apple’s approach is to either invest in these technology companies or directly acquire them

Does this mean OLED technology was not mature?

Yes, that’s right. Earlier OLED screens were limited by the craftsmanship of the time, white display was inaccurate, colors were overly saturated and vivid, color shifts at different angles, and a serious graininess were all urgent problems to be solved

According to the color spectrum chart provided by DisplayMate, the peak values of Samsung S3 in the transition from blue to green and yellow to red are significantly higher than those of the two iPhones, which can cause greens to be greener, reds to be redder, thus affecting the synthesis of other colors

Therefore, under the circumstances at that time,OLED screens did not demonstrate advantages over traditional LCDs, so Apple would definitely not use them

Secondly, at that time, OLED screens were not taken seriously, basically only Samsung was willing to invest in R&D, with insufficient production capacity and a very low yield, with only 10% yield in 2013

Considering that Samsung was the No. 1 in the mobile phone industry at that time, with a large number of phones using their own OLED, represented by the Galaxy S and Galaxy Note series, these two series alone had an annual shipment of tens of millions

On the other hand, the iPhone was even more exaggerated, with sales exceeding 100 million in 2012 and 200 million in 2015, although in recent years the sales have stabilized just over 200 million, even when converted to the new models of that year, it was still a huge amount

Given the production volume and yield at that time, even for Samsung, it was impossible to meet the huge sales of both their own and Apple’s phones. It is worth noting that the iPhone X was only launched in November due to insufficient OLED production capacity

So it seems like I’m saying OLED is worthless, but is that really the case?

What advantages does OLED screens have over LCD?

First, we need to mention the self-illumination. How do LCD screens emit light? Through LED lights on the backlight panel, simply put, it’s like a flashlight. Lei Jun has explained LED lights at a Xiaomi conference

How do you make the emitted light colored? At this point, you need to add a color filter membrane on the backlight layer

But I need to control the color ratio, I can’t just turn it into color, so at this time I need to add a liquid crystal layer between the backlight layer and the filter membrane

By changing the voltage through the liquid crystal layer, the amount of light is controlled, white light passes through the color filter membrane and is decomposed into colors, thus adjusting the ratio of the three primary colors. If you’ve studied physics or art, you know that the three primary colors can synthesize all the colors in the world

However, OLED is different, it does not require a backlight layer and does not need liquid crystals, taking Samsung’s RGB OLED as an example

Each pixel on the screen can emit light independently, with three light-emitting diodes, each containing a light-emitting material of one of the three primary colors

The benefit of this is that when all pixels are turned off, the screen is pure black

But LCD can only rely on blocking the liquid crystal to achieve black, and cannot achieve true pure black, but rather grayish white, far less deep than OLED, which often encounters this situation

Mobile phones emit light to display colors through pixels, but different colors require pixel points to constantly switch, and this switching time is called “gray scale response time“

If the gray scale is too long, visual drag will occur, which greatly affects image display (frame dropping may occur)

OLED screens almost do not have drag, there is no dragging, the screen response speed is much faster than LCD screens, while LCD performance decreases in low temperatures, making drag more obvious

If captured in slow motion, the drag of LCD becomes more evident, even for Apple’s top LCDs, it still drags when it drags, as shown in the image for iPhone XR

As mentioned earlier, the colors on the LCD screen are generated by filter membranes, which inevitably limits the color gamut, but OLED directly displays colors with pixels, allowing for a wider color gamut and a larger range of colors

OLED can display more and more vibrant colors, making the picture more vivid

It should be noted that in OLED light-emitting materials, the half-lives of the three colors are different, meaning the time required to decay to half of the maximum brightness. Among them, blue is the shortest, and green is the longest

So with usage, the screen will experience “aging”, with colors and brightness weakening

To alleviate this problem, Samsung added the “Pentile” subpixel arrangement, allowing for more red and blue diodes to compensate for the fast decay issue

This approach is different from the traditional RGB arrangement, as RGB uses subpixels of the same area, thus appearing less clear compared to LCD at the same resolution, especially in text delicacy

As compensation, Samsung increased the resolution to 2K level to avoid this and also launched a new diamond subpixel arrangement to optimize image delicacy and color accuracy

In recent years, OLED screens have significantly improved under Samsung’s training, with white not being pure, colors not accurate, and brightness not high all showing considerable improvement

In DisplayMate’s tests, Samsung’s flagship models in recent years have consistently ranked first, being hailed as the “world’s best smart display device” and this record has been continuously broken by itself

Continuously setting records for the most accurate color accuracy, the widest color gamut coverage, the highest peak brightness, and so on

Today, Samsung monopolizes over 90% of the mobile phone OLED market, for small-sized panels, Samsung is the spokesperson for OLED

Moreover, Samsung has the highest yield rate in the industry. Recently, reports of “BOE’s yield rate significantly improving” reveal Samsung’s yield rate

Reports indicate that in the third quarter of 2018, BOE’s yield rate for 6.39-inch QHD+ flexible AMOLED panels was just over 10%, while in the fourth quarter, it had exceeded 30%

Entering 2019, the yield rate is expected to continue to rise, with the end of the year expected to exceed 50%

As for Samsung, it has already reached 80%, truly no comparison, no harm

It is precisely because of the high quality and high yield of Samsung’s OLED that Apple commissioned Samsung to customize a screen that is on par with Samsung’s highest standards, except for the 3D Touch module inside the screen, the entire screen is produced by Samsung

Moreover, to create an ultimate full-screen experience, Apple also adopted COP packaging on the screen. What does this mean?

As shown in the figure, COF packaging bends the screen’s FPC wiring, FPC’s connection port, and touch components to place them under the screen. What are the benefits? This approach can minimize the bottom bezel of the screen

If traditional COG methods were used, it would retain a large chin like earlier iPhones, while Apple made the surrounding bezels equal in width for visual balance, with a thickness of only 3.4mm, still the shortest chin in the mobile phone industry

However, Samsung’s flagship also adopts COF packaging starting from the S8, but Samsung has not yet been able to remove the forehead, to maintain visual balance and durability, the chin is still retained

According to iFixit’s teardown diagram, it can be seen that the components of the Samsung S9 are also flipped to the bottom of the screen. It’s not that Samsung doesn’t want to eliminate it, but just to leave room for itself to play

From the latest exposure of the Samsung S10, this generation’s chin has basically reached the width of the iPhone

However, to achieve COP packaging, the screen must be OLED. The OLED screen substrate can choose flexible materials to achieve bending characteristics

To customize the screen on the iPhone X, Apple spent over $100, which is two to three times the previous cost. The wool comes from the sheep, which also became an excuse for the iPhone price increase

Apple has indeed created an unprecedented iPhone, while also making consumers pay a unique price

The overall performance of OLED screens has surpassed LCDs, gradually becoming the mainstream of the future. In 2018, the vast majority of flagship phones have embraced OLED

Why did Apple adopt OLED? The answer is simple, OLED is good enough, it can bear the future!