GB753601A - Improvements in or relating to television camera apparatus - Google Patents

Abstract

753,601. Television. FERNSEH GES. Dec. 30, 1953 [Jan. 16, 1953], No. 36166/53. Class 40 (3). [Also in Group XL (a)] Disturbances produced in the output picture signal of image type picture signal generating tubes, where the image being televised is illuminated by intermittent light (e.g. A.C. gasdischarge lamps) are corrected by combining with the picture signal output a correcting signal produced by the flow of secondary electrons emitted by the storage electrode, it being stated that these electrons are modulated at the same frequency as the disturbance signals but in opposite phase. In the described embodiment the secondary electrons are collected by two portions 6, 7 of the signal electrode from which the insulating layer forming the storage electrode 1 is removed. The signal electrode, via potentiometer 9 and load resistor 8, is maintained at a potential which is positive with respect to that of the final anode of the tube so that the signal developed across load resistor 8 and fed to the video amplifier 17 comprises the desired picture signals together with the disturbance signals and, in addition, the disturbance signals of opposite phase. Cancellation of the latter signals is therefore effected. Framing electrodes 2, 3, 4, 5 surrounding the rectangular image area and maintained at a suitable potential via potentiometers 11, 12, 13, 14, are provided for " shading signal " correction.