Monitoring and controlling quality of pen markings on plotting media

摘要

A method of monitoring and controlling the quality of pen markings on a plotting medium by qualifying each pen based on optically sensing across a sample line drawn on an actual medium. During each subsequent plotting task of a particular pen which has been qualified, an actual line plot is optically sensed across a selected point to make a comparison with the sample line. If the actual line plot is unsatisfactory, the deficient pen is replaced and the plot is restarted from the beginning, or retraced from the last good verification, or is stopped to allow the user to select an appropriate corrective procedure.