Discontinuity processing apparatus for automatic curve tracing system

Claim 1

In a pattern tracing method which operates by alternately performing a round scan of the periphery of an elemental area and moving the center of said round scan an incremental distance comprising the steps of: performing a round scanning operation along the periphery of an elemental area on said surface, each scan including sensing a regular line of spots on said periphery for detecting the presence or absence of said pattern from spot to spot; storing for each said scan digital code information in response to detected changes in said presence or absence of pattern, said code identifying the location on said line of spots of each branch of said pattern traversed by said scan; comparing a stored previous value tracing direction code with said digital code information and storing a tracing direction compared value; comparing a stored previous value tracing forbidden direction code with said digitAl code information and storing a tracing forbidden direction compared value; detecting the minimum values of respective stored tracing direction and tracing forbidden direction compared values; storing from said stored digital code information for said branches those codes corresponding to said minimum values as a tracing direction code and tracing forbidden direction code, respectively; moving the center of said round scanning operation over the surface containing said pattern by said incremental distance corresponding to an adjacent position for said elemental area and in one of a set of predetermined directions, the selected direction corresponding to said stored tracing direction code; transferring said tracing direction code and said tracing forbidden direction code to up-date the respective said stored previous value codes at each said scan; and repeating alternately said performing said round scanning operation and said moving said center said incremental distance to trace said pattern, the improvement characterized by: counting the number of branches of said curve for each said scan; interrupting said moving of said center an incremental distance when only a single branch of said curve is detected in any scan; increasing the size of said scan in response to counting a single branch of said curve in any scan; and resuming said predetermined round scanning operation and said moving said center alternately upon detection of two or more branches per scan.