US Patent 7133031 Optical system design for a universal computing device

The universal input device provides a common user interface for a variety of different computing platforms including printed documents. Using the present system, one may use the universal input device to control various computing devices as well as capture handwritten electronic ink and have the electronic ink be associated with new or stored documents. The universal input device can be identified by a specific identification in order to allow for multiple users to operate on a document and/or within an application program simultaneously or not. An off-set optical system with infrared illumination handles perspective and helps detect positional encoding which can be covered by existing ink under common visible light illumination.