| 摘要 |
<p>PURPOSE:To deliver the potential signal of a high level and to detect assuredly a pressing operation regardless of the position of a pressing point, by shifting the overall potential of a resistance film to the high potential side before the pressing operation is detected and flowing a minute current to the resistance film. CONSTITUTION:Two resistance films 1 and 2 are provided, and the transistors (TRs)Q1-Q4 are connected to the electrodes 1A and 2A as well as to electrodes 1B and 2B of the films 1 and 2 respectively. These transistors are controlled alternately by an FF1, and the driving voltage +V and an earth potential are applied to the transistors. The potential levels VX and VY obtained by pressing the films 1 and 2 are detected by the switches SW1 and SW2 which work through AND gates AG1 and AG2, and the coordinate data of the pressing point is applied to a processor unit PU. Then the TR Q2 is made nonconductive with the output signal of a TR Q6 before detecting a pressing operation, and a minute current which is decided by the impedance at the input side of a TR Q5 and an integration circuit ITG2 and the resistance value of the film 1 is flowed to the film 1. Thus the potential signal of a high level is delivered regardless of the position of the pressing point.</p> |
