Picture display device provided with an electron gun, and electron gun for use in such a device

A picture display device comprising an envelope containing a luminescent screen and an electron gun for producing at least one deflectable electron beam for propagation to the screen, said electron gun including a main lens system for variably focusing said at least one electron beam as it is deflected across the screen, said main lens system including:

• a. an arrangement of successive electrodes having respective apertures for passing the at least one electron beam, said electrodes including, in the direction of electron beam propagation:
• (i) a first electrode;
• (ii) at least one intermediate electrode, preceded by the first electrode;
• (iii) a final electrode, subsequent to the at least one intermediate electrode;
• b. voltage distribution means electrically connected to the arrangement of successive electrodes for, upon the application of a first voltage to the first electrode and a final voltage to the final electrode, effecting the application of an intermediate voltage to each of the at least one intermediate electrodes, each said intermediate voltage being intermediate and substantially different from said voltages applied to the immediately-preceding and the immediately-subsequent electrodes;
• c. means for applying a dynamic potential to the first electrode;
• d. a first coupling capacitor electrically connecting the first electrode and a first intermediate electrode.