System for cancellation of background information and signals resulting from non-homogeneity characteristics of a thermal imagery tube

Claim 1

AN INFRARED IMAGE TRANSLATION SYSTEM COMPRISING A THERMAL IMAGE SCANNING PICKUP TUBE HAVING A RADIATION SENSITIVE TARGET AND MEANS FOR GENERATING AND DEFLECTING AN ELECTRON BEAM FOR DERIVING ELECTRICAL SIGNALS RESULTING FROM THE SCANNING OF SAID TARGET WHEN AN IMAGE IS IMPRESSED UPON SAID TARGET, SAID SYSTEM ALSO INCLUDING A CATHODE RAY DISCHARGE DEVICE HAVING A DISPLAY SCREEN AND MEANS FOR GENERATING AND DEFLECTING AN ELECTRON BEAM FOR SCANNING SAID DISPLAY SCREEN, SYNCHRONIZING MEANS FOR CAUSING THE SCANNING OF THE ELECTRON BEAM IN SAID THERMAL IMAGE SCANNING TUBE AT A FREQUENCY EQUAL TO TWICE THE FREQUENCY OF SCANNING OF THE ELECTRON BEAM IN SAID DISPLAY TUBE, MEANS FOR INVERTING AND DELAYING SIGNALS RESULTING FROM EACH SCANNING LINE BY AN AMOUNT EQUAL TO A SCANNING LINE INTERVAL, MEANS FOR ALGEBRAICALLY SUMMING THE INVERTED SIGNALS RESULTING FROM SELECTED SCANNING LINES AND THE UNINVERTED SIGNALS RESULTING FROM OTHER SCANNINGS LINES TO PROVIDE COMPOSITE SIGNALS, AND MEANS FOR SUPPLYING CERTAIN OF SAID COMPOSITE SIGNALS TO SAID CATHODE RAY DISPLAY DEVICE.