Importance

Loading Importance Indicators...

Abstract

A noiseproof digitizing apparatus for digitizing the coordinates of a point on a tablet having grid conductors disposed along X and Y coordinate axes includes a cordless pen having a conductive end for transmitting an electrical signal to the grid conductors through of electrostatic capacitive coupling. An AC signal generator generates an AC signal and applies a balanced output of the AC signal to the conductive end, such that electrostatic capacitive coupling between the conductive end and the grid conductors causes a major balanced AC signal component and two minor unbalanced AC signal components to be produced in the grid conductors in response to the AC signal on the conductive end. A power supply supplies electrical power to the AC signal generator. A signal level measuring device measures the level of a signal current resulting from a sum of the major balanced AC signal component and the two minor unbalanced AC signal components produced in the grid conductors. A processor is provided for processing the measured signal level to determine a coordinate of the conductive end of the cordless pen.

Loading the Abstract Image...

First Claim