Flip phones ruled the mobile world until smartphones took over with their touchscreen slabs. However, we might soon be folding our phones in half again – if Samsung has its way.

Foldable smartphones are coming, and as with curved screens - from the Galaxy Note Edge up to the Galaxy S9 and beyond - Samsung appears to be leading the charge. For a few years now, the company has been sharing concepts of foldable and rollable smartphones, and a flurry of patent applications and rumours suggest the first models are coming very soon.

Samsung intends to make fully functional smartphones with flexible displays that allow you to fold the phone shut and tuck it in your pocket – and maybe even phones that open up to reveal a full-sized tablet screen within, or touchscreen devices that roll out of a tube.

Sound crazy? Maybe. Seem expensive? Undoubtedly. Is it exciting? Absolutely. Here's everything we know about the so-called Galaxy X phones so far.

Setting the table

What you might not realise is that Samsung has been quietly preparing us for this future for the past several years. Back in 2011, Samsung released a concept video that showed a flexible AMOLED phone that's little more than a technological piece of translucent paper: much more advanced than what's actually coming anytime soon, but a truly inspired creative spark all the same.

Much more realistic is the above video that shows a smartphone that opens up to become a tablet – or rather, a tablet that folds in half to reveal a smartphone on the outside. However you choose to frame it, we've heard that idea come up again in a recent report, so it might be pretty close to the real thing.

We suspect that Samsung has been waiting for the tech to match its ambitions, but that timetable keeps shifting. In early 2015, a Samsung Display representative said that "the commercialisation of foldable smartphones will be possible in 2016."

Indeed, Samsung was apparently so far advanced with its plans that it was reportedly showing off the new phone behind closed doors at this year's Mobile World Congress. It was a prototype, admittedly, but the investors and mobile operators that saw it were reportedly "very impressed" with the concept.

The wallet phone

From the outside, in its fully open and extended state, the Galaxy X phone could look pretty similar to a typical Samsung flagship phone: it has one large touchscreen on the front, cameras on both sides, and perhaps a home button below the display. It's a smartphone.

Only this smartphone does something quite surprising: as this patent application illustration shows (via Patently Mobile), the phone can fold right in half, fully covering the screen and making the phone about half its normal size. That makes it more pocket-friendly, plus it keeps the display nicely ensconced within the shell.

On the outer edge of the hinge is a charging contact, not unlike those seen on smartwatches, and you can pop the Galaxy X phone into a charging cradle to juice it up. Unfortunately, that suggests that the phone cannot be used while charging, much like wearable devices, since the contact is hidden while the phone is fully open. Guess that's the price of advancement, huh?

How does it work?

That's the most realistic Samsung illustration we've seen to date of the foldable design, but there have been other sketches and concepts seen over the last couple of years. One constant has remained true between them: that amazing new hinge system.

Samsung reportedly calls this initiative "Project Valley" because of that hinge: essentially, it creates a little pocket for the touch display to fold up without ever creasing. That small valley allows the phone to fold flat while allowing enough space for the screen have a slightly curve, preventing unsightly seams from appearing.

And then when you unfold the phone, the screen becomes fully taut, making it a properly useable smartphone. We're curious how different the screen will feel given the lack of outer glass, but we have to assume Samsung has found a way to make it work.

Fold or roll?

While the wallet-like design seems the most prominent one, there are other concepts too. Bloomberg reports that Samsung will release a foldable phone that resembles a makeup compact, which should be pretty similar to the wallet design in function, and also a 5in phone that unfolds to reveal an 8in tablet screen within.

In other words, the latter is the exact device seen in the video up top. And that's not all: a patent application uncovered in late 2015 included another illustration of that concept (above), with the phone screen appearing on the outside and the larger tablet screen unfolding from within.

Samsung's rollable device concept might be the most intriguing of the bunch, however. You can catch a quick glimpse of it at the end of the video up top, while Samsung showed an updated concept (above) in May 2016 at a display expo. It was also seen in a patent application in late 2015.

One version of the rollable phone features a small touchscreen on the cylinder, with a dialer app and quick access to various apps, while the full touch display rolls out from the tube. However, the newer version shown above appears to be for tablet or television use and doesn't seem to have app functionality on the tube itself.

Samsung may still be finalizing the use cases for these concepts, but the idea of a slim, travel-friendly tube that unfurls into a full-size, functional touch screen is very intriguing indeed.

The DS-phone

Here's the latest patent illustration (via LetsGoDigital), which was filed in April 2017 and emerged online in December 2017. It shows a dual-screen approach that can't help but remind us of the Nintendo DS and 3DS portable game systems.

In short, rather than having a bendable screen, this approach would have two rigid screens with a hinge between them, giving you the option to use one screen as usual or expand out and use two side-by-side, offering almost tablet-like dimensions in sum.

It's essentially the same kind of concept as the ZTE Axon M, which costs as much as a flagship phone but comes with lesser tech and a bulky design. Not the most exciting of the bunch here, Samsung – and hopefully not what we ultimately get from the Galaxy X after years of leaks and hype.

Galaxy X-pectations

For a few years now, we've been expecting a Galaxy X announcement right around the corner... and it still hasn't arrived. However, Samsung's mobile president Koh Dong-Jin told reporters in September 2017 that they aimed to release a phone with a bendable screen in 2018.

According to the Korea Herald, Samsung may make up to 100,000 phones in a limited run, to test the technology and see how well it goes over with customers, before moving on to full-scale production.

That same rumour pegs a 4K-resolution display for the phone, which seems overly ambitious given the power needs for such a screen, but it would certainly be a showstopper. A Quad HD (2K) display like that on the Galaxy S9 seems more reasonable, but we'll have to see whether Samsung opts to pull out all the stops for its first foldable phone.

Samsung loves pioneering these totally out-there concepts, and we saw the super-niche Galaxy Note Edge quickly evolve into the immensely popular Galaxy S6 Edge and Galaxy S7 Edge, with the Galaxy S8 ditching the flat-screen option. Will foldable smartphones be its next surprise success story?

Earlier in 2018

Will 2019 finally be the year that we see Samsung's foldable phone? Analysts say yes: the Korea Times reported in June 2018 that tech analysts believe that Samsung will finally make its move next year.

According to the report, Samsung confirmed in a recent earnings call that the company is indeed working on a foldable phone, affirming the years of leaks and patent drawings that we've compiled. A Samsung representative said that they're working on a device with a "true foldable display."

Shinhan Financial analyst Park Hyung-woo suggests that the phone will have a 4.5in display when folded up, which then opens up to a sizable 7.3in screen when unfolded. It's said to have that one smaller display on the outside, and then the separate, larger display on the inside when you open up the handset. He expects OLED displays on the device.

It won't be cheap, however. Kim Jang-yeol, who heads up research at Golden Bridge Investment, suggests that the foldable phone will carry a price tag of about million won – which comes out to more than £1,350 as of this writing.

What you're looking at above is a purported shelved prototype of Samsung's folding phone. Photos were posted to Weibo in June 2018, and it looks much like a pair of standard smartphones connected by a hinge. Actually, it looks a lot like ZTE's Axon M, but reportedly from a few years ago.

This probably isn't the kind of phone we'll actually see from Samsung, but if legitimate, it's an interesting example of the kind of road Samsung has been on in recent years.

UPDATE: It looks like the stage may be set for a debut at the Consumer Electronics Show (CES) in January 2019. That's according to noted leaker Ice Universe, who tweeted the theory in July 2018.

He suggests that Samsung will use the storied show to launch the foldable curiosity, while saving a reveal of the Galaxy S10 for the following month at Mobile World Congress 2019 in Barcelona. With several weeks between the early January and late February events, that would provide some distance between Samsung's big headline phones for next year.

The Latest

It's official: we will see Samsung's foldable phone before the end of 2018.

Samsung's mobile CEO DJ Koh confirmed the decision to CNBC during IFA 2018, telling the site that market research had finally convinced Samsung that they'd find buyers for such an experimental device. He suggested that their biggest challenge was setting a foldable smartphone's expanded form apart from that of a typical tablet.

"You can use most of the uses... on foldable status. But when you need to browse or see something, then you may need to unfold it. But even unfolded, what kind of benefit does that give compared to the tablet? If the unfolded experience is the same as the tablet, why would they (consumers) buy it?," says Koh. "So every device, every feature, every innovation should have a meaningful message to our end customer. So when the end customer uses it, (they think) 'wow, this is the reason Samsung made it'."

Koh "hinted" that a debut at the Samsung Developers Conference in November is likely, although it's not yet known whether the device will release before the end of the year. It's possible that we'll get a partial debut at the conference, and then a more extensive launch at CES 2019 or another event next year.

He added that the development of the device was "complicated," but that they had "nearly concluded" it. In any case, that's the most concrete suggestion we've seen of a impending launch to date. It's finally happening! (Probably.)

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