| 摘要 |
<p>PURPOSE:To detect a position with a high precision, by dividing the surface of a plane plate into n-number of continuous areas to read the position on the plane plate by n-order higher harmonic components and using fundamental wave components to discriminate which area the position exists. CONSTITUTION:A coordinate reader 10 cooperate with an AC magnetic field generator 11, a driving part 13 which supplies phase-shifted driving signals to this generator 11, and a magnetic field detector 12 constituting a pen. A rotating magnetic field M is generated above the plane plate provided on the generator 11 and is different in phase as shown by arrows. The position of a pen 12 is detected on a basis of the alternation of the phase. Then, the area and the position in it where the pen 12 is placed are detected accurately. The signal of fundamental wave components is used to detect where this area exists. A detecting winding 14 in a detector 12 senses only fundamental wave components, and a curve C' is extracted from a detector 16. A detecting winding 15 senses only n-order higher harmonic components, and a curve C is extracted from a detector 17. A processing circuit 18 deduces an object coordinate position on a basis of information of curves C and C'.</p> |
