Coordinate measuring system for points on drawing or text - has pen with transmitter over wireless link to receivers and processor calculating position

摘要

The system for selected points on a drawing or section of text uses a pen that transmits signals over an infra red or ultrasonic link. The book or document is located on a table and the pen (G) is located over the selected point. Located around the edge of the table are a number (5,6,7) of receivers that respond to the signal generated by the pen based transmitter. The receivers are coupled to a remote data processor that determines the co-ordinate position based upon phase difference caculations.