FLAT PLATE TYPE CATHODE-RAY TUBE

摘要

PURPOSE:To obtain a picture with uniform luminance over the entire screen by providing an electron beam amount detection electrode outside at least a single effective screen of two or more electrodes arranged on the screen side of a vertical deflection electrode. CONSTITUTION:A beam that passed through a beam extraction electrode 3 is focused and deflected by a vertical focusing.deflection electrode 4 and incident on a first beam current detection electrode 15. This current is detected by a detector 31 and compared with a required and preset current value. The difference is input to a beam extraction electrode voltage control circuit 32 and the voltage supplied to the beam extraction electrode 3 is controlled. Consequently, the beam current that is incident on the first beam current detection electrode 15 can always be obtained a preset fixed current value. For the detection of beam current, the same beam permeation hole as a first shielded electrode 5 may be formed on the first beam current detection electrode 15 and the beam passing through the hole may be obtained by a second beam current detection electrode 17.