folding phones of 2019, which is more reliable?

Huawei has named the folding phone’s structure “Falcon Wing”(鷹翼式) and its specialists have been taking a shot at this plan for a long time. When you crease the cell phone, there are no holes between the cell phone’s front and the back. Huawei says there are more than 100 parts on the cell phone’s pivot, which it has licensed.

For Huawei, each pixel size is roughly 0.05 mm or 50 microns or 414 ppi

采取四层结构设计，最上面一层是高分子材料的屏幕保护层，第二层是可弯曲的柔性屏幕，第三层是软胶支撑片，最下面一层是转轴。

转轴的重要性和难点在于，屏幕和转轴是一个耦合关系，涉及到复杂的运动原理。在屏幕硬件长度不变的情况下，手机弯折和伸展的过程中，HUAWEI Mate X需要通过转轴结构的自动伸缩，实现对0-180度开合状态下的屏幕进行同步、精准、连续的支撑。

在每一个角度下，转轴的部件都要基于运动原理沿着一个导轨运动，并精准伸出对应的长度，来配合屏幕的位移和受力。如果出现运动误差，屏幕就会在挤压和伸展时受到损伤，进而影响手机的使用寿命。

Samsung Galaxy Fold:

The  bend radius in Samsung Fold is ~ 1.5mm. Whereas 4.4 mm bend radius in Moto Razr V4.

Conclusion:

When folded( ie when phone is not in use), Huawei's screen is stretched. Samsung's is not. Samsung's better

The stretch ratio, Samsung's(2.5%) is less than Huawei's(5%). So Samsung's is less stretched.

The bending area, Huawei's is larger(15mm diameter) than Samsung(3mm diameter), and less stressed to screen. Huawei's better

For the hinge design, Huawei's is much more complicated.  From KISS principle, Samsung's better.

So overall, I think Samsung's design is better than Huawei's

Moto Razr V4

The hinge in Moto Razr is shorter in length on Moto Razr V4, so less sideways movement allowed when open or close action, quite likely more durable than Samsung's. 

The Moto Razr V4 has larger bend diameter of ~ 8.8mm (less stress). So Moto Razr V4 is quite likely better than Samsung.  Also to reduce the crease in the hinge area, there is spring mechanism to pull flat the crease area when you unfold the phone.

 All these three models show crease on the folding line. Samsung > Huawei > Moto.

Huawei says that not to unfold the phone for under -5 deg celsius.???

Considering the better hinge design in Moto Razr V4, especially the larger bend radius and the shorter hinge length, I think Moto Razr V4 will be more reliable than Samsung Fold.

compare Samsung Fold vs Huawei Mate X vs Moto Razr V4

2023:

Update from Samsung flip 5, techwave

Copy of moto razr?