Microsoft has filed a patent application which would give large-scale touchscreen computers, such as its Surface multitouch table, a dynamically changing display capable of physically presenting keys, buttons and other controls. The technology would rely on a layer of light-induced shape-memory polymer across the touchscreen surface, and which could be controlled by ultraviolet light to either protrude and harden or relax and soften.
Coupled with a rear-projection system, as on Surface, the table would therefore be able to create, say, the physical feel of a QWERTY keyboard onto which the key labels themselves would be projected. The polymer response is switched on and off with different wavelengths of ultraviolet light, invisible to the human eye.
Touchscreen effectiveness for interactions like typing is generally less than for hardware peripherals, because of the absence of tactile feedback helping the fingers find their way. However, it's unclear what potential the system might have for tablets and phones, which would presumably require display panels capable of accurately creating sufficient ultraviolet light for the polymer to respond.