Cathode ray tube trajectory correction device - applies steady potential to screen and superimposed steady and varying control potential to grid

摘要

A device is used to obtain a correction of the trajectory of the electron beam in a cathode ray tube using a penetrating screen for polychromatic or persistent displays. The tube (1) has an electron gun (2), electron beam (5) and multilayer screen (3). The screen (3) is at a steady potential which defines the penetration of electrons in the screen (3). A grid (4), near the screen (3), is at a varying potential superimposed on a steady potential. The varying potential is related to the angle of deflection of the electron beam (5) by a parabolic law and such that the electron impact point on the screen (3) is almost the same whatever the energy of the electrons. By changing the potential of the screen a change in persistence or colour can be obtained.