| 摘要 |
<p>PURPOSE:To improve the recognizing accuracy and to deal with the attenuation and the disturbance of signals with a coordinate input device by detecting the vibration phase difference of a vibration sensor and the sine wave vibration of a vibration pen and recognizing the coordinates, with use of plural cycles of the sine wave vibrations. CONSTITUTION:The sine wave vibration of a certain fixed frequency is produced by a vibration pen 3 and sent to an arithmetic/control circuit 1 after the waveform phase is measured by a signal phase measuring circuit 9. The circuit 1 stores the frequency and the phase of the pen 3. The another frequency is produced and its phase is measured. These operations are repeated by several times for calculation of the distance set between the pen 3 and a vibration sensor 6. Meanwhile the circuit 9 amplifies the signal of a drive signal producing circuit 12 and the signal of the sensor 6 and then applies the filter processing and the A/D conversion to these signals. Then the circuit 9 detects the A/D conversion data or an ultrasonic signal of the sensor 6 and then samples and holds it for execution of the Fourier transformation. Thus the circuit 9 detects the phase difference between the sine wave vibration of the pen 3 and the vibration of the sensor 6.</p> |
