Patent ID: 8912927

Claim:
A method for determining an incline angle of an electromagnetic pointer, the electromagnetic pointer being positioned on or above a digitizer, the digitizer having a plurality of loop antennas, said method comprising steps of: A. locating a peak-value loop antenna which has a maximum inductive signal value; B. scanning plural loop antennas that are near to the peak-value loop antenna and obtaining seven inductive signal values from seven loop antennas among the peak-value loop antenna and the neighboring loop antennas; C. simulating one signal curve with a cubic equation in one variable for every four adjacent points taken from the seven signal values, in which highest-ordered parameters for four signal curves obtained from the simulation respectively are A −2 , A −1 , A 0 , and A 1 in order; D. defining following variables by calculating variations among the signal curves: Index1= A 0 −A −1 Delta L=A 0 −A −2 Delta R=A 1 −A −1 Index2=Delta L −Delta R; E. determining an inductive distance between the electromagnetic pointer and the digitizer according to values of DeltaL and DeltaR; and F. determining an incline angle of the electromagnetic pointer by using values of Index1 and Index2 to look up an incline angle conversion table.