| 摘要 |
<p>A position detector which has a plurality of loop coils arranged in parallel with one another in the position detecting direction, and which is adapted to determine a coordinate value of a position, which is designated by a position indicator having at least a coil, on the basis of the electromagnetic action between the position indicator and the position detector. One loop coil is selected simultaneously from each of a plurality of groups among a plurality of loop coils so that not less than a predetermined number of the relative positions of these selected loop coils do not become the same or symmetric in each group and over a plurality of groups. A loop coil on which the position indicator is positioned is determined among the loop coils on the basis of the pattern of a signal amplitude obtained by this loop coil selection. This makes it unnecessary to select all loop coils at the time of starting a position detecting operation, and serves to reduce the time required to determine the coordinate value. When the coordinate value is determined, the digital data corresponding to an arbitrary AC signal are converted into an analog signal, and a reception signal is sampled at a predetermined cycle to convert the signal into digital data. These digital data are subjected to predetermined computation to calculate amplitude and phase angle with respect to an arbitrary frequency component in the reception signal, whereby the concurrent use of a plurality of coordinate indicators is effected easily.</p> |
