| 摘要 |
<p>PURPOSE:To detect the accurate coodinates of a position at a low cost by a plane resistance tablet and an input pen based upon an electrostatic capacity coupling system. CONSTITUTION:This coordinate input device is constituted of a tablet 8 having plural dot-like signal detecting electrode terminals on end points opposed to a plane resistor having a uniform resistance value, a signal pen 1 for transmitting an electric signal to the tablet 8 by electrostatic capacity coupling, electrode selectors 4 to 7 for switching dot-like signal detecting electrodes, current/voltage converters 21, 22, analog switches 18 to 20 for switching a differential input, a differential amplifier 23, a band pass filter 24 for cutting out an unnecessary signal, a rectifier 25 for rectifying a signal to a DC signal, and a control part 27 for executing control and arithmetic processing for respective parts. When two unbalanced signals are current/voltage converted and a differential signal between the converted signals is inputted, the influence of noise and floating capacity is suppressed and the influence of dispersion in the ON resistance of the switches 18 to 20 is compensated, so that the detection accuracy of a coordinate position can be improved.</p> |
