Photosensitive inspection apparatus for filamentary material

Claim 1

A FILAMENTARY MATERIAL INSPECTION APPARATUS COMPRISING A HOUSING HAVING A FIRST WALL AND A BASE, A GENERALLY CYLINDRICAL BARREL EXTENDING THROUGH SAID FIRST WALL INTO SAID HOUSING, A HEATER ADJACENT ONE TERMINAL PORTION OF SAID BARREL DIRECTING A BEAM OF RADIATION INTO SAID HOUSING; MEANS IN SAID BARREL DEFINING A SLOT FOR RECEIVING A RUNNING LENGTH OF FILAMENTARY MATERIAL THEREBY FORMING A SHADOW IMAGE OF SAID MATERIAL; REFERENCE ELEMENT MEANS IN SAID BARREL FORMING A SHADOW IMAGE OF SAID ELEMENT GENERALLY PARALLEL TO AND SPACED FROM SAID FILAMENTARY MATERIAL SHADOW IMAGE; DETECTOR MEANS ADJACENT THE BASE OF SAID HOUSING COMPRISING AN ELECTRICAL BRIDGE CIRCUIT INCLUDING A PHOTOSENSITIVE CELL, SAID BRIDGE CIRCUIT HAVING A VARIABLE OUTPUT DEPENDENT ON THE QUANTITY OF RADIATION IMPINGING ON SAID PHOTOSENSITIVE CELL; AND OSCILLATING REFLECTOR MEANS IN SAID HOUSING IN LINE WITH THE BEAM OF RADIATION ADAPTED TO ALTERNATELY PROJECT THE RESPECTIVE SHADOW IMAGES ON AND OFF OPPOSED PERIPHERAL PORTIONS OF SAID CELL, WHEREBY THE OUTPUT OF SAID DETECTOR MEANS IN A FUNCTION OF THE DIFFERENCE BETWEEN THE FILAMENTARY MATERIAL DIAMETER AND THE REFERENCE ELEMENT DIAMETER.