System for automatically digitizing engineering drawings

Claim 1

An electro-optical computer-controlled scanning system adapted to accurately and rapidly digitize an original engineering or other line drawing having a horizontal X dimension and a vertical Y dimension and to store the resultant digital data, making it possible to reassemble a stored drawing with virtually the same fidelity as the original drawing, said system comprising: A a laser beam scanner having a wide-angle deflector to sweep the beam in X and Y directions to a degree sufficient to traverse the entire X and Y dimensions of the drawing being digitized and a narrow-angle deflector whose operation is independent of the wide-angle deflector for sweeping the beam in the X and Y directions to a degree sufficient to examine any selected, relatively small region of the drawing; and B computer means associated with said scanner and including a digital memory to extract digital information from the line drawing and to store this information to ensure the capture of virtually all information thereon, said means operating in a two-mode procedure, in the first of which the wide-angle deflector operates to make a survey along a narrow stripe extending in the X direction across the entire drawing to determine whether any drawing information is contained therein, the scanner skipping one stripe width in the Y direction if no information is found to carry out a like survey of the next stripe; and if information is then found, only the X coordinate thereof is noted and stored in said memory, the survey being completed when the scanner has skipped to traverse the entire drawing in the Y direction, an automatic switch-over to the second mode being made when a survey on a given stripe results in a finding, the second mode being a line follower operation in which the narrow-angle deflector of the scanner operates to examine each drawing line to determine its radius of curvature and singularities, each line then being thereby defined as a vector, this two-mode procedure being repeated until the entire drawing is examined and digitized.