Abstract:
A pattern contour-tracing system which is capable of intercepting and locking on the pattern contour from a position removed from the contour without the use of a leadin contour. The pattern contour-sensing head is pointed so as to travel in a line toward the contour with the sensing head steering means locked out until the sensing means detects that the sensing is within a predetermined distance of the contour. The steering means is then unlocked so that the sensing head can be automatically steered by the servo means to make a smooth transition into the path defined by the pattern contour. A photosensitive tracing system is disclosed which is operable to lead into and trace the pattern contour whether the contour is defined by a line or an edge.
Abstract:
The following specification describes a tracing scanning head having a photocell for sensing the presence of a pattern. The cell is supported on one shaft of a pair of coaxial shafts for movement transverse to the shaft axes. A pinion carried by the other shaft engages a rack carried by the one shaft for moving the photocell in response to rotation of the other shaft to compensate for the kerf or tool cutting width. A servo motor armature is fixed to the one shaft and rotates the one shaft and photocell to maintain the photocell angularly aligned with the line. A pair of easily readable knobs are provided at the upper end of the shafts to permit the offset to be easily determined. A preamplifier is carried by the one shaft to amplify low level photocell signals before they are transmitted over slip rings and brushes, and a neon bulb shielded by a metal ring casting lights the drawing pattern. A transparent shield depending from the casting protects the photocell lens. A pair of lamps cast indicia on the paper to enable the direction of scanning head travel to be easily ascertained.