Position detecting device and position detecting method

A position detecting method for calculating a position indicated by an indicator, the position corresponding to one or more intersections of X-axis electrodes formed by a plurality of conductors that are arranged substantially parallel to each other and Y-axis electrodes formed by a plurality of conductors that are arranged substantially parallel to each other and that extend perpendicularly to the X-axis electrodes, the method comprising:

• generating a synchronous clock signal at the timing when an AC signal to be supplied to the X-axis electrodes passes through a zero-cross point;
• selectively supplying the AC signal to the X-axis electrodes at the timing of the synchronous clock signal, which is generated at the timing of the AC signal passing through a zero-cross point;
• selecting one of the Y-axis electrodes at the timing of the synchronous clock signal, which is generated at the timing of the AC signal passing through a zero-cross point;
• detecting a signal outputted by the selected one of the Y-axis electrodes;
• and
• calculating the position indicated by the indicator based on the detected signal.

A position detecting device comprising:

• X-axis electrodes formed by a plurality of conductors that are arranged substantially parallel to each other;
• Y-axis electrodes formed by a plurality of conductors that are arranged substantially parallel to each other and that extend perpendicularly to the X-axis electrodes;
• a driving section configured to supply an AC signal to the X-axis electrodes;
• a synchronous clock generating section configured to generate a synchronous clock signal at the timing when the AC signal is zero:
• a first change-over switch configured to selectively supply the AC signal to a determined electrode among the X-axis electrodes at the timing of the synchronous clock signal, which is generated at the timing of the AC signal being zero;
• a second change-over switch configured to select a determined electrode among the Y-axis electrodes at the timing of the synchronous clock signal, which is generated at the timing of the AC signal being zero;
• a synchronous detector configured to detect a signal outputted by the Y-axis electrodes through the second change-over switch, and outputting the detected signal;
• and
• a position calculating section configured to calculate a position indicated by an indicator on the position detecting device, based on the signal outputted from the synchronous detector, the position corresponding to one or more intersections of the X-axis electrodes and Y-axis electrodes.