Samsung presented a patent application for a both sides expandable display smartphone.
This Samsung's latest patent centers on a traditional smartphone body that could greatly expand its display to watch wide screen content by simply pulling out both the right and left retractable sides as noted below in Patent figure 2.
As you're able to see in Samsung's patent FIG. 2 above, there's a fixed display in the center of the smartphone noted as D1 that's present in FIG. 1 as well. Once the smartphone's display is expanded, the user will have two extra display portions noted above as Displays DA2 and DA3.
Samsung's patent FIG. 15 above illustrates a cross-sectional view of a reduction mode of an expandable display smartphone #500. In an expandable display device #500, the first guiding portion #25 includes a first inclined guiding portion #251 connected to the first roller housing #22, and a first flat guiding portion #252 connected to the first inclined guiding portion #251. The first inclined guiding portion allows the flexible display panel #70 to be smoothly slid by the flexible display panel being gently bent.
The second guiding portion #35 includes a second inclined guiding portion #351 connected to the second roller housing #32, and a second flat guiding portion #352 connected to the second inclined guiding portion #351. The second inclined guiding portion allows the flexible display panel to be smoothly slid by the flexible display panel being gently bent.
This type of smartphone could accommodate viewing home videos, movies, widescreen TV and playing games. The tradeoff would appear to be that the smartphone would have to be thicker than most premium smartphones today.
Samsung filed their U.S. patent application back in July 2017 and it was made public last week by the U.S. Patent and Trademark Office. Considering that this is a patent application, the timing of such a product to market is unknown at this time.