| 摘要 |
<p>PURPOSE: To detect a tilt and a turning angle of a position indicator by arranging plural magnetic cores close to each other and controlling coils to be short- circuited except a selected coil so as to adopt the thin position indicator. CONSTITUTION: Two magnetic cores are arranged in the vicinity of a pen of the position indicator 15, a coil (18, 21) is wound on each core, each coil is connected to a capacitor (19, 22) to form resonance circuits 20, 23 resonated at a frequency coincident with that of a radio wave sent from a tablet. A detection circuit 25 connecting to the resonance circuits 20, 23 via a switch 32 connects to an integration circuit 27 with a large time constant, a detector 26 connects to an integration circuit with a small time constant and a switch 33 is used to short-circuit the coil 18 or 21. Furthermore, the switches 32, 33 are interlockingly controlled by an output of a latch circuit 31. Thus, the interference between the magnetic cores is prevented and the tilt and turning angle of the position indicator is precisely detected even around a valid area of the position detector.</p> |
