Abstract: The phototracing system for controlling the motion of the work-performing member of a two-coordinate copying machine for pattern-cutting of sheet materials, wherein the tracing photo-head cooperates with a template drawing wherein the line being traced is represented as a "black" to "white" transition, by means of an optical scanning beam. The aperture of the optical beam in the plane of the template drawing has finite dimensions and is driven through a circular scanning motion at a permanent angular speed about the optical line of the tracing head.The phototracing system includes a train head with a photoelectric transducer connected with two shapers of short pulses of the signal of the prefixed instantaneous change from "white" to "black" and from "black" to "white", respectively. The output of the second shaper of the short pulse of the prefixed instantaneous change from "black" to "white" has connected thereto means for delaying each pulse.

Abstract: A photo-copying device for controlling displacement of the working member of a metal gas-cutting machine following the line of the contour being copied, comprising a photoelectric transducer which provides circular scanning of the line of the contour being copied by means of an optical scanning beam for detecting the points of intersection of said beam with said contour line, the path of said beam in the contour plane being a circumference with its center lying approximately on said contour line, the optical scanning beam moves along said path at a constant angular speed and intersects said contour line at two points; a source of reference signals in the form of sine and cosine voltages; a first and a second drives for moving said photoelectric transducer along the X and Y axes, respectively; a third and a fourth drives for displacing said working member of the gas-cutting machine along its guides which are taken to be X and Y axes; a first and a second converters for converting instantaneous values of a cosi