Large area electronic writing system

Abstract

Collaborative work on an interactive system is facilitated by accurately capturing and displaying information on an interactive system, wherein multiple persons may work together for supplying and receiving information with a single large area display. A large area electronic writing system is provided which employs a large area display screen, an image projection system, and an image receiving system including a light emitting pen. The display screen is designed with the imaging surface in front of the substrate, with a thin abrasion resistant layer protecting the imaging surface from the pen tip. The screen is held together with dowel pins pressed through the layers, and is curved to provide pressure for holding the layers together and mechanical rigidity against flexure during writing. The imaging surface disperses light from both the projection system and the light pen. The image receiving system comprises a very large aperture lens for gathering light energy from the light spot created by the light emitting pen. The amount of energy from the light spot which reaches the integrating detector is more critical to accurate pen position sensing than the focus of the light spot, so that the aperture of the lens is more important than its imaging quality. The light emitting pen is modified to additionally disperse light at its tip.