| 摘要 |
<p>PURPOSE:To obtain a high converting speed and high accuracy by setting two reference voltages and calculating the center position of a cursor from the time up to these reference voltages so as to detect a coordinate position. CONSTITUTION:When exciting currents are sequentially impressed on loop coils xn and ym from an oscillator 2, electromotive force corresponding to the intensity of a magnetic field is generated from the cursor coil 5. When the output from the coil 5 is passed through a smoothing circuit 8, an output voltage curve can be obtained. Two reference voltages VA and VB, where an output waveform can be conceivable to be a straight line with respect to the output voltage, are set at a level lower than the peak value of the output voltage from the circuit 8. These reference voltages and the output of the circuit 8 are given to a comparator 9, whose output is inputted to a counter 10, whereby the time when the counter 10 reaches the reference voltage and the time where the peak value is attenuated to the reference voltage can be obtained. These times are stored by the counter 10, and an arithmetic part 40 calculates a coordinate position. This constitution will not requires A/D conversion.</p> |
