Microsoft has applied for a patent which addresses one of the major disadvantage of touch-screen devices for input: the lack of tactile feedback.

The patent, filed back in May 2009 but only published by the US Patents and Trademarks Office yesterday, is entitled "Light-induced shape-memory polymer display screen" - and spends much of its time dazzling the reader with science, detailing "a display screen having a topography-changing layer including a light-induced shape-memory polymer [which] further includes an imaging engine configured to project visible light onto the display screen, where the visible light may be modulated at a pixel level to form a display image thereon [and] further includes a topography-changing engine configured to project agitation light of an ultraviolet band towards the display screen, where the agitation light is modulated at a pixel level to selectively change a topography of the topography-changing layer."

In layman's terms, Microsoft's patent is for a special type of touch-screen display which includes a 'shape-memory' layer at its base. When activated by a special frequency of ultraviolet light, individual blocks - not-coincidentally the same size as a pixel on the display part - can be raised or lowered, lending the displayed image physical texture.

The upshot of the design is an image that can be felt as well as seen - for example, an on-screen keyboard with dips between the keys just as with its physical counterpart. Better yet, the 'keys' could even depress when you touch them - providing touch-screen keyboards with the all-important tactile feedback that they currently lack.

While there's no sign of a product using Microsoft's patented technology on the horizon, it's an interesting technology - and could prove indispensable on future iterations of dual-screen products like Acer's recently announced Iconia, which dispenses with a physical keyboard in favour of a second touch-screen display, in order to avoid the discomfort of long periods of text entry on an on-screen keyboard.