| 摘要 |
<p>PURPOSE:To cancel the distribution capacity between a shield sheet and an electrode sheet by connecting a conductive part of the shield sheet to an operational amplifier inputting the voltage of the electrode sheet and forming a voltage follower in a pressure-sensitive coordinate input device using a resistance film. CONSTITUTION:When the surface of the shield sheet 7 is depressed by a writing tool or the like, pressure-sensitive rubber 5 on a depressed point is connected and the voltage of the resistance film 2 on the depressed point is guided to the electrode sheet 6 and inputted to an input stage operational amplifier 8 of a voltage detecting circuit. The output of the operational amplifier 14 acting as a voltage follower is equanl to that of the electrode sheet 6 on the plus side input terminal and has low output impedance, so that noise sent through the capacity between a human body and the shield sheet is absorbed. Since the same voltage is always applied to both the ends of the distribution capacity between the shield sheet and the electrode sheet, the existence of the distribution capacity is neglected from the view point of circuit operation.</p> |
