On March 30, Xiaomi launched their first foldable smartphone branded the Mi Mix Fold that's equipped with a large 8.01” WQHD+ resolution flexible internal display and a 6.52” external display which is reportedly the largest foldable display on any smartphone to date. It's definitely going to put pressure on Samsung who has already lowered the price of their Galaxy Z Fold 2 to be more in line with Xiaomi's pricing. And today we've learned that both Oppo and Google have filed patents showing their interest in joining the foldable device space.  

Earlier today Patently Apple discovered that Chinese smartphone vendor Oppo is also working on a foldable smartphone according to their published patent application 20210096596 made public on April first.

A Google Foldable Device Patent Application

Perhaps more interesting is that the U.S. Patent Office published a folding device patent from Google this morning titled "Hinge Mechanism by Gear Set with Slider for Foldable Display Device."  The device could be a smartphone, tablet or netbook. Google first describes the issues with  current foldable devices and then points to their patent pending solution.

Google notes in their patent filing that display devices (e.g., organic light-emitting diode (OLED) displays) may include a flexible display coupled to a housing member, which may fold or bend in a rotating manner about a hinge assembly. In some instances, the flexible display can be bent or folded such that the flexible display can face each other e.g., rotated 180.degree. In other words, a portion of the flexible display can be bent towards a portion of the flexible display that remains fixed or stationary.

However, the bending of the flexible display may cause malfunction or breakage of the flexible display. Further, in some occasions, the bending action may cause a portion of the flexible display to become unattached (e.g., separated, decoupled, unconnected, etc.) to the housing member and form a ridge. In other words, a lifting or curling phenomenon of the flexible display caused by an excessive folding operation in an area corresponding to the hinge assembly can be formed. This causes unnecessary deformation and/or an uneven surface, which may distort images on the display.

Other flexible displays, which employ a hinge assembly, may use multiple shafts rotation hinges to fold the display. However, flexible displays using multiple shafts rotation hinges can be complex and include many parts. This may lead to more frequent breakage and expensive repairs. In most cases, one broken shaft or hinge will require replacement of the entire hinge assembly.

Other flexible displays may include a biasing member (e.g., a spring) to rotate the hinge assembly. However, in this configuration, the biasing member causes a "pop-out" action (e.g., a rapid opening of the display device) to rotate the display device to an open position. In other words, the display device opens to a predetermined angle and cannot stop at various rotation angles. Moreover, in the above configurations, the display devices are generally larger and thicker due to the various parts required.

In order to resolve the outlined issues, exemplary foldable display devices, as described in Google's patent filing, may include a hinge assembly having a slider mechanism and a set of gears. The slider mechanism and the set of gears operate to transfer a rotational movement into a translational movement of one of a first housing or a second housing.

More specifically, the hinge assembly can transfer a rotational movement (rotatable 180.degree.) of the flexible device to a translational movement (e.g., sliding), and bend the flexible device without damage or breakage.

Further, due to the translational movement, a flexible device can be completely attached (e.g., coupled, connected, affixed, etc.) to both of the first housing and second housing during folding and/or unfolding of the flexible device. In other words, there is no lifting or curling effect formed on the flexible display.

Google's patent FIGS. 1A and 1B below illustrate schematic views of an exemplary display device. The device is seen to be offering a fold that is off-center. Google claims it could be a foldable smartphone, tablet or netbook.  

Google's patent FIG. 2A is a top view of an exemplary display device (#10 - without the display #100).  The hinge assembly 150 may include at least a slider 151.

Google's patent application 20210109572 was published today by USPTO. It was originally filed for in December 2020, which proves that it's a recent project.

With LG out of the market, especially in North America, Google might want to fill that gap and a new economical foldable smartphone could spark some excitement. On another front, a foldable tablet or netbook could possibly compete with Lenovo's foldable device and others that will be making their way to market by Q4. 

Of course, it's a patent filing, which doesn't guarantee Google will ever pull the trigger on this invention. Though I'm sure that Google fans are hoping they will.

To know what Apple is up to on this front, you could always review our archives covering foldable and scrollable devices.