AN IMPROVED OPTICAL PATTERN TRACING SYSTEM

摘要

An optical pattern tracing system of the type having a tracing head with a scanner that projects a photocell onto a pattern in a closed path and provides two signals for each complete path across a line with an approach control for driving the tracing head toward the pattern-line that permits the operator to preselect either clockwise or counterclockwise tracing. The tracing head approach control includes circuitry that selectively blocks the first or the second pulse from the photocell and then terminates the blocking function shortly after the line is reached. An improved line detector is also disclosed that detects the true center of the line to be traced, and a dual pulse detector is also provided that assures that the scanner is fully locked onto the line prior to switching from manual to automatic control.