The problem with a folding phone is that the front can easily become the back, and when closed anything on the actual back of the device is inaccessible, including the camera if that is where it is located.
The solution has generally been to turn the selfie camera into the main and only camera of the device, but this does result in some compromises.
In a new patent, Microsoft has proposed a solution that actually makes turns the problem into an advantage.
They propose that the camera is divided into two segments – one a rear-facing (631 in the image above) that may be wide angle.
They also suggest that the second half of the device has lenses (636 in the image above) which are placed so that they cover the original camera when closed and convert it to a more narrow field of view.
In this way, a single camera can be both front-facing and rear facing and also be optimized for each role, and thickness may be saved by splitting the lens arrangement over both sides of the device.
Microsoft also proposed that the camera may also be arranged side-ways, with a mirror to bring in light from the outside, similar to a periscope, to once again limit the impact of the camera and lens assembly on the thickness of the device.
Microsoft also proposes that the flash of the camera may also punch through to the front of the device.
The lead inventor was Eero Tuulos, an ex-Nokia camera specialist who now works for Huawei. The patent was filed in June 2016 and published today. It is not known if Microsoft is still working on a folding smartphone, though some rumours have suggested the device is still in play.
See the full patent here.