A touch screen assembly including a display, infra-red light emitters, photo diodes, a transparent frame including an exposed upper edge along its perimeter, and internally reflective facets for directing light emitted by the emitters along light paths that travel upward through one side of the frame, over the display screen, downward through the opposite side of the frame, and onto the photo diodes, and a processor operative to identify a location of an object touching the display, based on amounts of light detected by photo diodes when light emitted by light emitters is blocked along its light path by the object, and to recognize the object touching an outer wall of the frame, based on amounts of light detected by activated photo diodes when light emitted by activated emitters is absorbed along its light path by the object at the outer wall, thereby providing touch sensitivity to the frame itself.