Angular input information system relative to a tablet for determining an incline angle of a pointer or stylus

摘要

A coordinate detecting device and an angle information detecting method which are capable of detecting tilt angles of a stylus pen with high accuracy. A coordinate detecting device is made up of a plurality of sensor coils and a position indicator housing an electromagnetic coupling means, and detects coordinates and tilt angles of the position indicator by sensing an induced voltage developed in the sensor coil by means of electromagnetic interaction. The coordinate detecting device is also provided with an angle information detecting means. This angle information detecting means correct errors in a value of a predetermined function including main and sub-peaks, the errors arising from a difference between a main peak induced voltage distribution and a sub-peak induced voltage distribution within a detection width of one sensor coil, by converting either the main peak induced voltage distribution or the sub-peak induced voltage distribution so as to be similar to the other one. Then, the angle information detecting means calculate tilt angles of the position indicator using a predetermined function including the sub-peak induced voltage and the corrected main peak induced voltage.