Folding devices that are now in the hands of consumers, and even showcased at IFA 2022 on Lenovo and Asus laptops, can enjoy their breakthrough year. If so, then we probably owe it to Samsung, who did the lion’s share of the work to make folding phones and flexible screens the mainstream.
How we got this far, and how Samsung’s estimated foldable Samsung Galaxy Z Flip 4 and Samsung Galaxy Z Fold 4 overcame countless design challenges is the story best told by an insider: someone like Dr. Won-Joon Choi, Executive Vice President, Flagship Team Leader Product Research and Development and the Technology Strategy team at Mobile eXperience Business, Samsung Electronics, who sat down with me at IFA 2022 in Berlin to reveal a whole lot of secrets about Fold’s design and development.
As Dr. Choi told me, Samsung is hoping that with foldable phones, as with large screen phones like the Galaxy Note a decade ago, the industry will change. That’s the line, along with the belief that folding is ready to go mainstream that Samsung likes to repeat to anyone who wants to listen – but I sense that with Choi, the sentiment relies less on marketing than on hard-won experience.
Building Z Fold and Z Flips was “very difficult … from our perspective there are many limitations and challenges to folding,” said Dr. Choi, who has been with Samsung since 2016 and actually has dual responsibilities as a leading flagship Research and Development and leading Samsung’s technology strategy team, where she builds strategic relationships with startups and global companies. This is something that plays a significant role in his work to help make Foldable’s three-year business a reality.
Dr. Choi has given me a rare look behind the scenes of the challenges and sometimes surprising solutions that his team encountered while developing foldable phones.
The key areas are:
- Screen size and usability
- S-Pen Compatibility
We also talked a lot about the fold. You know this is evident on both the 7.6-inch foldable display of the Samsung Galaxy Z Fold 4 and the 6.7-inch flexible display of the Galaxy Z Flip 4. But I’m ahead of myself. We cannot speak of a crease without first discussing the unusual ultra-thin glass-covered displays.
Samsung’s ultra-thing glass or UTG came after two generations of Folds, starting with the Samsung Galaxy Z Flip 3 and then rapidly moving to the Galaxy Z Fold 3. Various reports say external company Schott, supplies most of the flexible glass to phones, and Corning does the rest. It may be so, but Dr. Choi emphasized that it was a collaborative effort, largely driven by Samsung’s own R&D efforts.
It took years to develop flexible glass with a thickness of around 30 micrometers, which is based on multiple layers of panel technology. “When you see our innovation hit the market, it doesn’t come overnight. Of course, we start years earlier, ”said Dr. Choi.
Samsung didn’t introduce it to the early Folds, however, as they weren’t sure if it would work. When I asked him exactly who was making glass, Dr. Choi told me that when developing, they often had multiple paths “even for thin glass.”
One of the tracks is Corning, which already supplies glass for the back panel of phones. The next track is performed by the display partner (Samsung Display). The rest is “our own business or the research that makes UTG a reality,” said Dr. Choi.
I asked again who of the three makes glass? Dr. Choi says that “it is not one source”. There is research collaboration, although “we have many own IP addresses [intellectual property] to thin glass, “he added.
Dr. Choi confirmed that flexible glass does not belong to Corning, and neither does its manufacturing process.
After we went to the press, Samsung explained Dr. Choi and said, “The raw glass comes from many vendors, including Corning, but the Ultra Thin Glass process requires collaboration between different parties.”
Dr. Choi’s comments from our interview characterized it this way:
“You start with very thin glass, you make it thin and still strong enough and still bendable, and that takes a lot of work and of course this process is not done by Corning. So we work with Corning, but we do it Thin Glass is not made by Corning, something we do, and a different kind of process by our partners. It is all a combination. “
Over the years, I have interviewed Corning executives and seen some of their development work on ultra-thin yet flexible (non-bendable) glass. The ability to bend glass the way Samsung Folds does is a breakthrough. I asked Dr. Choi what that moment was when Samsung’s R&D department realized they had glass that could bend enough to handle foldable phones.
He smiled broadly and said, “Of course we were very, very excited.”
Despite this, Samsung is still working on improving thinness and durability, adjusting each display later and looking at materials, adhesives and thickness.
Could appreciate the challenge but had to ask about the fold as everyone asks me when I show them the Galaxy Z Fold 4.
On a 7.6-inch display, a fold is a solid line that runs across the screen. You can see it when the screen is off, and you can always feel it when you slide your finger across the screen. This is not particularly noticeable when using the display.
The fold exists because of the strength of the glass material and its need to keep what I believe is the default curved shape. In other words, when you unfold the glass you are unfolding what in its natural state would be a bit like a glass taco shell.
Samsung later told me that the process of inserting the UTG into phones and bending it doesn’t permanently curve it.
Understanding why this exists is one thing, but how do you get rid of it?
“That’s a fair question to submit. We believe [the foldable] it has reached a point where it can become mainstream, but that doesn’t necessarily mean we’re finished ”when Dr. Choi talked about getting rid of creases. “Crease reduction is definitely on the list. This is one of the technical challenges we want to overcome. “
How actively is Samsung trying to fix the problem? Dr. Choi told me that research goes in two directions. One looks at the size of the bow (that fold) when you completely fold the Z Fold 4 or Z Flip 4. Somewhat counterintuitive, you don’t want a smaller fold. A larger one would put less pressure on the display and possibly create a less noticeable crease as it would spread smoothly over a wider area of the display.
Materials are another route of inquiry. Different materials have different properties and may react differently to folding. Dr Choi said the display will still be glass, but some material attributes may change to create a different, less noticeable fold shape.
Dr. Choi laughed and told me that this was a question everyone was asking and solving it was now “part of his homework”.
The water resistance of phones with so many moving mechanical parts has also proven to be a challenge. Both folds have two bodies connected by a hinge. The technology on both sides is connected by a bit of a flexible PCB, which must pass through the holes in the housing on each side.
The team developed a series of innovations to protect fragile parts from the elements. For the holes, the phones use a rubber sealant. For more exposed hinges, they use anti-corrosion material. Finally, Samsung has developed new, waterproof components.
Along with the latest Z Fold, Samsung wanted to enlarge the cover screen, and I’ve already heard stories of how they redesigned the hinge to make it so. However, Dr. Choi added a little color to the research and development, telling me that his team went through “10-20 recipes to reduce size and weight for six to nine months. He kept failing and then decided to completely change the structure. ” This would not be the last time he described the development process as “regulations”.
When it was time to bring S-Pen functionality to the Galaxy Z Fold 3, they had to figure out how to place a rigid copper digitizer underneath the flexible screen. It was once again a trial and error process for Dr. Choi’s team. This time there were almost 100 recipes.
Finally “someone came into my office and said,” Hey Won-Joon, why don’t we just destroy this? ” Instead of one rigid copper digitizer, they will use two: one on each side of a 7.6-inch display.
Of course, this left a slight gap between the two panels. To remedy this, Samsung has developed an AI-based prediction algorithm that can predict where the digitizing S Pen will end up on the screen and automatically fill in small gaps.
Unfortunately, S Pen’s challenges are not over yet.
The thing about Fold’s flexible screen is that its natural screen shape is more like a “U” meaning it really wants to open along the edges. Samsung responds to this with nearly a dozen magnets arranged around the edges of the screen that keep it closed when folded. The problem was that these magnets interfered with the electromagnetic energy necessary for the digitizer to function. Initially, “50% of the digitizer could not detect the S-Pen,” Dr. Choi told me.
Solution? Maintain high magnetizing force when closed, but then rotate it down when the Z4 bend is unfolded,
Listening to Dr. Choi’s speech means understanding that the folded journey is not complete, but is just beginning.
Samsung’s ambition is to make foldable phones thinner and lighter. As with flagship cameras in devices, it will optimize every element. And folding phones are just the beginning. Dr Choi said Samsung is looking at many other factors in device shape – laptops, larger screens, and more – in terms of UTG and foldable display. However, Samsung says it will not build them unless it knows that such displays bring value to consumers.
Updated 9-5-2022 with explanations from Samsung.
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