| 摘要 |
<p>PURPOSE:To ensure the accurate detection of coordinates through a coordinate detector, by calculating the distance between a stylus pen and a tablet surface and corecting an X and a Y coordinates based on this calculated distance. CONSTITUTION:A sine wave of an axis X or Y having a phase difference from the voltage extracted out of a tablet 7 and processed, i.e., said sine wave is delivered to an amplifier 12 against said sine wave given from the filter 3. Based on this phase difference, a storage counter 14 is actuated, and the X and the Y coordinates are computed from equivalent pulses. While said sine wave is held at an amplitude detector and compared with the set value of a signal processor 15a. The signal level is lower than the set value if space exists between the tablet 7 and a stylus pen 5. Therefore amplification degree is increased for amplifiers 4a and 12a to set the value of a detector 6 larger then the set value. Then the distance between the pen 5 and the tablet 7 is obtained from the information of the amplifiers, and the value is corrected for both X and Y coordinates.</p> |
