A data tablet using electromagnetic induction.

A new data tablet using electromagnetic 1 induction is described. The position on the i tablet is detected by the sensor in the pen holder which is coupled with the rotating magnetic field whose phase varies linearly with the position of the pen on the tablet. In this method, the sensor height “h” and the phase change factor “a” of the generated magnetic field are selected as ah ± 1 so that the positional error caused by the pen inclination is readily compensated. The phase change factor of the magnetic field, in addition, is made so large that the reading accuracy is improved. As practical examples, an electromagnetic white hoard (size: 1.4 m x 1.06 m) and a tablet unified with a plasma display panel for teleconferencing equipment are described.