| 摘要 |
<p>PURPOSE:To prevent coordinate values from variation due to the variation of pen pressure by detecting the coordinates of X and Y axes individually and suppressing the change of input in-phase voltages of differential amplifiers at the time of respective detection. CONSTITUTION:When the initial state of a signal S is in the high level and is turned to the low level at a time T1 and the y axis is selected, change-over switches 22, 23 are set up to A and C sides respectively. Since a high level signal is outputted only for a fixed period tau by a holding control part 27 after the change of the signal S, both coordinate outputs X, Y hold preceding voltages until a time t2 and the positional information of pressure points of coordinate detecting sheets 2, 3 is supplied to the differential amplifiers 5, 6 respectively. Since a resistance value of a conductive point on a pressure sensitive conductive sheet 4 is varied by the influence of pen pressure variation Q, the in-phase voltage of the inputs X1, X2 of the differential amplifier 6 is changed in accordance with the pen pressure, but the in-phase voltage of the inputs Y1, Y2 of the differential amplifier 6 is not influenced by the pen pressure variation.</p> |
