Limbering up: the future of flexible phones

30th Dec 2013 | 12:00

Limbering up: the future of flexible phones

Getting wriggly with the phones of tomorrow

Imagine a smartphone that's bigger to look at then it is to carry around in your pocket. No, we're not talking about some fanciful Dr Who gizmo. We're talking about the near-future of smartphone design.

You see, the next big thing in smartphone display technology has nothing to do with resolution. There are only so many pixels packed into a square inch that the human eye can see, after all.

Nor are we talking about a bold new panel technology. In fact, this fantastical gadget that we're discussing today will use OLED technology, which has been around for years.

Rather, the future is fully flexible. The recently released Samsung Galaxy Round and LG G Flex are but tantalising glimpses of a whole new approach to mobile phone design. One that abandons the clumsy, fragile bricks that we carry around with us today in favour of something bendier and tougher.

Early steps

The aforementioned Galaxy Round and G Flex are only the first step on the road to fully flexible phones. You might be surprised to hear that they're even that, if you can remember the release of the Samsung Galaxy Nexus and the Nexus S before it.

Both Google-approved phones, which launched in 2011 and 2010 respectively, featured banana-like bends in their screens. Their similarity to the LG G Flex, however, was only skin deep.

Samsung Galaxy Nexus

These curved phones simply used curved glass to achieve their effect. The actual display panel was as straight and as rigid as ever. With the LG G Flex, meanwhile, the whole display bends subtly upward towards the two ends.

Of course, you might question the benefits of such an approach. LG would say that it mimics the immersive quality of its curved OLED TV sets when watching HD video - a kind of wrap-around effect that pulls you into the picture. There's also the fact that it fits the contour of your face more readily when making calls.

Material benefits

But the truth is, both the LG G Flex and the Samsung Galaxy Round are initial steps towards something completely different. In future, these bendy displays will be attached to similarly flexible bodies, creating whole devices that move and flex. Eventually, you'll be able to fold your smartphone up like a piece of paper.

The most immediate benefit of this technology, though, will be significantly tougher smartphones. Why? Because a key part of the development of these flexible phones is the replacement of fragile glass components with plastic ones.

Of course, that's the theory. In practice, replacing these traditional materials has posed a considerable problem for component manufacturers.

LG G Flex

There's a reason we still use such a heavy, fragile material as glass to cover a large part of our £600 smartphones. Glass isn't just handy for its transparency - it also acts as a brilliant barrier.

"It has been challenging to make robust enough flexible OLED displays," a spokesperson for Finnish tech company Canatu Oy told TechRadar. "Materials for OLED emitting layers are very sensitive to air and moisture, and it has been difficult to develop air and humidity-tight enclosure packages that withstand extreme repeated bending and folding."

It's very tricky to find a flexible polymer that can get close to the performance of good old glass when it comes to keeping out the elements. Of course, various material solutions have now been formulated, which is why the flexible phone revolution looks set to begin.

Enter OLED

As we've hinted at already, current and forthcoming flexible displays utilise the unique properties of OLED technology.

OLED stands for Organic Light Emitting Diode, which means that the thin layer of material that emits the light necessary for an electronic picture is made up of organic compound. Unlike LCD technology, each pixel in an OLED display lights itself, rather than relying on a separate backlight system.

That's why OLED displays appear so vibrant, with such deep blacks. Black OLED pixels are essentially pixels that haven't been turned on.

LG flexible OLED display

That lack of a backlight also relates to why OLED is so suited to being made flexible - and why LCD is not. OLED panels are far simpler, slimmer, and more self-contained than LCD solutions, and they can be laid on a plastic substrate rather than glass. In order words, they can stand up to being bent.

Of course, there are practical considerations when it comes to replicating this process on an industrial scale. Canatu Oy told us that "flexible backplane technology has been expensive and low yield" up to now.

We've actually had the screen technology to make flexible displays possible for some time. While there have been a number of false starts over the past 40 years relating to limited e-ink solutions, the likes of Sony have been demonstrating working flexible OLED displays since 2007.

However, those aforementioned manufacturing impracticalities have ensured that such designs never got beyond this experimental prototype stage and into a final product.

Samsung Youm

Samsung appears to have picked up the baton in recent years, and the company showed off a working flexible OLED display that it called Youm at CES 2013 (an earlier Samsung Galaxy Skin concept revealed in 2011 turned out to be the word of speculating students). This display could be worked into 'S' shapes, and formed into wrap-around display - one that goes off the edge and around the corner of a smart device.

But the key thing holding back the launch of fully flexible or foldable smartphones has nothing to do with the displays. It's everything else that makes up a smartphone that's the problem.

Power struggle

Put simply, while OLED screens can be made to bend, batteries, processors, and other vital internal components cannot. Or at least, they couldn't until relatively recently.

Back in 2011, the Korea Advanced Institute of Science and Technology announced that it had developed a fully flexible RAM chip. Enabling the reading, writing, and retention of data on a flexibly chip is essential to a fully flexible phone. Of course, refining such a concept to a practical, manufacturable level takes time, but the knowledge has been there for a while.

An even bigger obstacle in creating completely flexible phones has been creating a battery that can withstand similar manipulation. Batteries tend to take up a large part of a smartphone's mass. More problematically, they tend to be filled with liquid or gel-like substances, which don't lend themselves well to heavy flexing. In fact, doing so can be downright dangerous.

The solution has been to create a solid (or semi-solid) state battery. These will be much safer under load, and it's now just a question of ensuring that this new safe battery technology is up to the task of powering a multi-core smart device for an entire 16 hour day - something that even existing rigid battery designs can struggle with.

Early electronic printing techniques have proved expensive and impractical, but promising solutions to this key issue are starting to be found. Professors at New Jersey Institute of Technology (NJIT), for example, have come up with a flexible battery that utilises carbon nanotubes.

As well as being flexible, this battery technology is fully scalable. "This battery can be made as small as a pinhead or as large as a carpet in your living room," said NJIT professor Somenath Mitra.

LG flexible batteries

Meanwhile LG Chem recently announced that it had produced a kind of cable battery that could be bent and even tied into a knot without heating up during use. It probably won't be ready for mass production for another few years, though.

LG's great local rival, Samsung, is also working on flexible solid state battery technology which will bend without catching fire.

Other vital smartphone components appear to be ready to make the jump to a flexible format. The aforementioned Finnish company Canatu Oy has just launched its fifth generation of Carbon NanoBud (CNB) films, which enable the replacement of indium tin oxide (a solid conductive material) in capacitive touch sensors.

"Our production line for CNB films and touch sensors is in operation and marks an important milestone going to volume manufacturing," explains a Canatu Oy spokesperson, adding that there are plans for a mass volume plant in the second half of 2014.

In other words, here is another vital component in flexible touchscreen displays that is just about ready to roll out to commercial products.

Give and take

So, given the break-throughs in these key technological areas, when will we see properly flexible phones in our shops?

Industry insiders believe that it's less than two years away. "Canatu estimates (the) first fully foldable products will be in the market in 2015," claims a spokesperson for the company.

It's an estimate that appears to back-up the projections of the smartphone manufacturers themselves. According to a slide the company recently showed to investors, Samsung anticipates that its first bendable smartphone will be ready to go in 2014, while its first fully foldable smartphone will be on the market either towards the end of 2015 or the beginning of 2016.

And don't for one minute think that this is likely to be another dead end gimmick to file alongside phones with 3D displays. Dr Kinam Kim, president and CEO of Samsung Display, recently told analysts that "flexible display penetration could rapidly increase to 40% by 2018."

That's not to mention the technology's virtually guaranteed adoption by the automotive and fashion industries. Expect the cars of the near future to feature dramatically swooping digital displays that mould and form to the shape of a dashboard, and shirts that utilise paper thin and stretchable OLED displays to alter the colour and pattern of the 'fabric.'

It seems as if the future really is flexible, and it's going to be phones that lead this somewhat bendy-legged charge.

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