Patent Document ID: 5502514
Application ID: 08475996
Patent Status: 1

Claim One:
1. An apparatus for sensing position of a stylus relative to a projected image where a digital micromirror device (DMD) array is used for projecting said image upon a surface, said DMD array including a plurality of controllable pixel mirrors, said image created by directing light from a first light source onto said DMD array which controllably reflects said directed light through an optical system onto said surface, said image comprised of a plurality of sequentially projected frame images where there is a finite time duration between successive projected frame images, said apparatus comprising: a second light source and a means for illuminating said surface with light from said second light source; said stylus including a reflector for reflecting said second light source light from said surface back towards said surface; energizing means for scanning by selectively energizing said plurality of controllable pixel mirrors during said finite duration between successive projected frame images; a detecting means for detecting the presence of said reflected second source light on said surface when reflected by at least one of said controllable pixel mirrors; and address means, responsive to said detecting means and said energizing means, for providing a stylus position output when said detecting means detects said reflected second source light from said surface during said finite duration.