| 摘要 |
<p>PURPOSE:To output an output signal with constant voltage even though a tablet and a stylus pen are separated as far as the good SNcan be provided by providing the tablet, carrier wave switching circuit, stylus pen, and control circuit and feeding back a signal outputted by a signal amplification and detection circuit. CONSTITUTION:Plural electrode lines 19 and 21 in the X and Y directions of a tablet 2 are arranged on transparent glass platets 18 and 22. A X carrier wave switching device 4 and Y carrier wave switching device 5 apply pulses on electrode lines 19 and 21 in succession. A stylus pen 9 is coupled with the electrode lines 19 and 21 of the tablet 2 to detect the pulse applied to the electrode lines 19 and 21. A control circuit 16 makes the detection signal of the stylus pen 9 constant. By feeding back signals outputted by the amplifiers 11 and 13 and a detector 12, the detection signal from any position in the effective area of the tablet 2 can be made constant and the influence of the noise level on the signal can be prevented.</p> |
