A Microsoft patent application 2010/0295820, published yesterday, covering a novel way to construct a "tactile" touchscreen -- a display that uses technical tricks to convince users they're actually touching the ridges, bumps and textures of a displayed image.
Whereas previous screens produced only an illusion of texture, Microsoft proposes producing a real texture, using pixel-sized shape-memory plastic cells that can be ordered to protrude from the surface on command.
A projector built into the Surface displays a computer image onto the table top from below. As the user touches it, infrared reflections from their fingertips are detected by cameras beneath the table and used to pinpoint the position of the finger and lend touchscreen capability.
In the patent, Microsoft proposes coating the display with a light-induced shape-memory polymer. This becomes hard and protruding when one wavelength of ultraviolet light is transmitted at a pixel, and soft when another wavelength hits it. By modulating these wavelengths, texture can be created, the patent claims.