Mobile phones that incorporate pico projectors have long been under development by most of the world's leading handset manufacturers. Sony Ericsson, however, has now filed a patent for a handset that not only contains a projector, but also a miniature screen on which the projected images can be viewed.

The company has filed for a patent in the US for a 'Mobile Communication Device with Built-In Projecting Screen'. Prototype images of the device show a conventional smartphone handset with a fold-out, telescopic screen surface onto which images from the integrated pico projector can be thrown.

The patent application suggests that the screen could be made out of a material that could exist in dual states: offering flexibility for storage purposes and rigidity for when it is in use.

Online feedback about the device from technical experts has been somewhat bemused, with many pointing out that the prototype's screen is scarcely bigger than the traditional LCD screen featured on a conventional smartphone handset.

There have also been queries about the status of the projector itself, which apparently can only be used with the built-in screen and cannot be used to create images on external projection surfaces.