Automatic conversion of line records to digital information

It is often necessary to convert line records to digital form for use on a digital computer. A conversion attachment for a conventional X-Y recorder has been built for this purpose. The ordinate is scanned from bottom to top and the digital equivalent of the Y-deflection voltage at incidence of a dark line is made available for recording on an incremental tape recorder. The incidence of the dark line is detected by using a cadmium sulphide photocell and an illuminating arrangement. The system described can be used for single-valued functions but can be easily modified to handle multivalued functions. In the Y-direction there are 123 levels of quantization. In the X-direction the quantization is 20/cm at present. This can be varied depending on the sensitivity in volts/cm of the X-Y recorder. The tape is compatible with IBM 7044 computer systems.