Microcomputer-controlled digitiser for curves on a strip chart not including sharp peaks

Abstract

A microcomputer-controlled assembly for a curve reader was constructed. The chart is set on a pulse-driven pen recorder and an optical sensor (reflection-type photointerruptor) is installed on the pen holder so as to move for scanning in parallel to the Y-axis. The value of X is increased with a pre-selected increment and the Y-value of a curve is determined as the mid-point of the width of the curve. A curve down to 0.3 mm wide could be located with a precision of 0.1 mm. The precise coordinates of a point could be determined when the point is given as the intersection of two pencil-drawn straight lines. Data obtained are stored in memory and can be reproduced on a printer.