High-speed film reading

Claim 1

APPARATUS FOR THE AUTOMATIC READING OF FILM OR THE LIKE, COMPRISING A LIGHT SOURCE INCLUDING MEANS FOR SELECTABLY PRODUCING ILLUMINATION INDEPENDENTLY AT EACH OF A PLURALITY OF SITES ON A DISPLAY SCREEN, FIRST AND SECOND PHOTOTUBE MEANS PRODUCING ELECTRICAL SIGNALS RESPONSIVE TO LIGHT TRANSMITTED THERETO, OPTICAL MEANS DIRECTING ONE PART OF THE ILLUMINATION FROM EACH OF SAID SITES TO CORRESPONDING DISCRETE SITES ON SAID FILM AND DIRECTING ANOTHER PART OF SAID ILLUMINATION TO SAID SECOND PHOTOTUBE MEANS, OPTICAL MEANS DIRECTING ILLUMINATION TRANSMITTED THROUGH SAID FILM TO SAID FIRST PHOTOTUBE MEANS, OPTICAL FILTERING MEANS INTERCEPTING AT LEAST ONE OF SAID PARTS OF SAID ILLUMINATION DIRECTED TO AT LEAST ONE OF SAID PHOTOTUBE MEANS FOR SELECTABLY VARYING THE RELATIVE ELECTRICAL OUTPUT SIGNALS FROM SAID FIRST AND SECOND PHOTOTUBE MEANS TO COMPENSATE FOR FILM DENSITY EFFECTS, MEANS COMPARING THE OUTPUTS OF ELECTRICAL SIGNALS PRODUCED BY SAID FIRST AND SECOND PHOTOTUBE MEANS AND DEVELOPING SIGNALS CHARACTERIZING THE RELATIVE VALUES THEREOF WHICH SIGNIFY THE PRESENCE OF INFORMATION OF INTEREST CARRIED BY SAID FILM, MEANS PROGRAMMING SAID LIGHT SOURCE TO PRODUCE A SCANNING OF ILLUMINATION AT THE SITES ON SAID SCREEN, AND MEANS SENSING THE SIGNALS DEVELOPED BY SAID COMPARING MEANS AND IDENTIFYING THEIR OCCURRENCES IN RELATION TO COORDINATES OF THOSE SITES OF ILLUMINATION ON SAID SCREEN WHICH CAUSE THEM TO BE PRODUCED.