Foldable smart phones are the next iteration in display technology. The latest news from the Apple camp is on a patent showing a foldable iPhone. Of course such gimmicks were seen earlier also by the likes of Samsung and many mockups by others too.
But now that the need and the market for bigger displays is on the rise, we can see the requirements for a foldable display. Smart phones of 5 inches have become the norm while 5.5 inches are the 'Max/Plus' companion of each smart phone. This trend will be taken even further by this years end when Oppo R9s series of phones will be released. The Oppo R9s is the base model with the size of 5.5 inches while the Oppo R9s Plus will be 6 inches.
So, there is definitely a trend to go larger. But the 'Bar' design can be used normally with one hand or even by using two hands at only so much size. Even the 5 inches models are hard to operate by just one hand and the 5.5 inches required you to use two hands to operate.
The solution is foldable displays. Now, foldable displays do sound a good solution to get bigger displays but they also pose a problem. What would the user use/see when the hold their phone. A phone of such a design will require additional screen(s) on the fold that will be facing the user. Also, the 16:9 ratio results in nearly a square when folded.
What is the most comfortable width our hand can hold without getting uncomfortable. Lets look at some of the prevailing sizes (considering only the display size and not the additional bezel):
(All sizes are in inches, bezel-less, and considers the Bar-Portrait 16:9 view)
| Diagonal Size | Width of the Phone | Height of the Phone |
| 4.0 | 2.0 | 3.5 |
| 4.5 | 2.2 | 3.9 |
| 5.0 | 2.5 | 4.4 |
| 5.5 | 2.7 | 4.8 |
| 5.7 | 2.8 | 5.0 |
| 6.0 | 2.9 | 5.2 |
| 6.4 | 3.2 | 5.6 |
| 6.8 | 3.3 | 5.9 |
| 7.0 | 3.4 | 6.1 |
| 8.0 | 3.9 | 7.0 |
In my opinion the most that we can hold for longer periods is around 3 inches and not more. Also, the average shirt's pocket is also around that size.
Also, we would fold the phone by its height in terms of the 'Bar/Portrait' view. This means we would kind off letting go of the Portrait view and use the phone only in the 'Landscape' view. Even when folded the display would be held such that opening the fold will show the 'Landscape' view.
So, if we consider 3 inches (width) to be the folded size and obviously the opened size will be 6 inches (width), what sort of dimensions are we looking at. Lets calculate. Remember that we now use the 'Landscape' 16:9 view.
| Width when Folded | Width of the Phone | Height of the Phone | Diagonal Size |
| 3.00 | 6.00 | 3.38 | 6.88 |
The above is the best dimensions.
Lets also consider the widths of today's phones and how would they translate in a foldable design:
| Width when Folded | Width of the Phone | Height of the Phone | Diagonal Size |
| 1.96 | 3.92 | 2.21 | 4.50 |
| 2.20 | 4.40 | 2.48 | 5.05 |
| 2.45 | 4.90 | 2.76 | 5.62 |
| 2.69 | 5.38 | 3.03 | 6.17 |
| 2.79 | 5.58 | 3.14 | 6.40 |
| 2.94 | 5.88 | 3.31 | 6.75 |
| 3.15 | 6.30 | 3.54 | 7.23 |
| 3.33 | 6.66 | 3.75 | 7.64 |
| 3.43 | 6.86 | 3.86 | 7.87 |
| 3.92 | 7.84 | 4.41 | 9.00 |
Lets also see the diagonal sizes when the phones will be folded:
| Width when Folded | Height when folded | Diagonal Size |
| 3.00 | 3.38 | 4.52 |
| Width when Folded | Height when folded | Diagonal Size |
| 1.96 | 2.21 | 2.95 |
| 2.20 | 2.48 | 3.31 |
| 2.45 | 2.76 | 3.69 |
| 2.69 | 3.03 | 4.05 |
| 2.79 | 3.14 | 4.20 |
| 2.94 | 3.31 | 4.43 |
| 3.15 | 3.54 | 4.74 |
| 3.33 | 3.75 | 5.01 |
| 3.43 | 3.86 | 5.16 |
| 3.92 | 4.41 | 5.90 |
In addition, when folded the display ratio is 1.125 which is very close to being a Square.
Hmm, so, will the folded design be worth it. At only one fold, as we can see above, the ideal size would result in only a 6.88 inch screen when opened. Isn't this size already available. There are many 7 inch voice calling tablets available and >6 inches phablets too.
In conclusion, I think we would require a triple fold or a roll design to get the most of such a design. Hmm, need to brush up on an Origami lesson.
