Improvements relating to electron discharge devices such as television transmission tubes

摘要

665,279. Electrode materials and processing. ELECTRIC & MUSICAL INDUSTRIES, Ltd. Dec. 20, 1949 [Dec. 31, 1948], No. 33562/48. Class 39 (i). In sensitising the photo-electric mosaic in a sealed discharge tube, such as a television transmission tube, the screen is oxidized whilst it is exposed to a light image of different. intensity levels and is scanned to produce electrical signals, the oxidation being terminated when the signals indicate that a required degree of sensitization has been obtained. A pick-up tube, adapted to operate with cathode potential stabilization, has its mosaic support coated by the evaporation of antimony, or of bismuth and silver alternately through a mesh, the removal of which is followed by deposition of calcium. The tube is then evacuated and sealed, mounted in a camera and a light image of alternate black and white squares projected on to the screen. Oxygen may be released by heating a side tube or capsule containing potassium chlorate, barium oxide or silver oxide, which, alternatively, may form a coating on a platinum or tantalum heating ribbon. Oxidation is terminated when the difference in signal levels corresponding to the black and white squares in a television receiver is observed to be a maximum.