Patent ID: 7305368

Claim:
Apparatus for inputting at least alpha-numeric information into a computer comprising: a projector, projecting an image of at least part of a keyboard, including a plurality of keyboard locations, onto an inert surface; a single two dimensional sensor comprising: at least one infrared illuminator generating a generally planar beam generally parallel to said inert surface; an array of discrete sensing elements; and at least one lens operative to image light scattered by a user indicator at a region of said generally planar beam overlying each of said plurality of keyboard locations onto a corresponding at least one of said array of discrete sensing elements, said at least one lens mapping said plurality of keyboard locations onto said array of discrete sensing elements, such that each of said plurality of keyboard locations on said image of at least part of a keyboard is defined by at least one of said array of discrete sensing elements, said single two dimensional sensor sensing user indicator interaction with specific ones of said plurality of keyboard locations on said image of at least part of a keyboard; and at least alpha-numeric information generation circuitry receiving an output from said single two dimensional sensor for providing an at least alpha-numeric output on the basis of said mapping.