Samsung Display reportedly filed a patent in September 2018, published in January 2019 and discovered by Lets Go Digital, for a foldable smartphone with a clamshell design.
Unlike most clamshell designs however, the patent filed by Samsung Display suggests the company is planning to have the display on the outside of the device, rather than the inside. The patent also suggests that the device would be compact in size, offering some form of hinge system in the middle that will allow the device to fold flat, unlike Royole's FlexPai that has a gap next to the fold.
Other features indicated by the patent show some form of lock system that appears to allow the device to lock in various positions. It is not clear how exactly that might work as yet, but the patent suggests the display should be seamless when unfolded. The Galaxy Fold appears to have a slight crease when unfolded so we hope any new devices manage to avoid that.
Bloomberg reported that Samsung was planning two more foldable phones with new designs, one of which was thought to be a clamshell with a smaller external display, similar to what Lenovo might be planning for the rumoured foldable Motorola RAZR. The other was thought to have a screen around the outside, like the Huawei Mate X.
The Samsung Display patent suggests a mix of the two devices reported, though it's worth remembering many patents never see the light of day so take it with a pinch of salt for now.
Meanwhile, the Samsung Galaxy Fold will go on sale in April so if a foldable Samsung device is what you're after, the Galaxy Fold is your only option for now.