Abstract: A picture display device comprises an evacuated envelope and is provided at a first side with an electroluminescent display screen and at an opposite side with an electron gun (6). Between the electron gun (6) and the display screen, the device comprises deflection means with which an electron beam generated by the electron gun (6) can be deflected during operation. The electron gun (6) has at least an electron beam-generating portion (20) and is provided with a main lens system (40) having a first electrode (41), a final electrode (45) and at least one intermediate electrode (42-44) across which a main lens voltage is gradually applied step-wise during operation so as to form an electron-optical main focusing lens. The intermediate electrode(s) (42-44) comprise a plurality of separate parts (421-423, 431-433, 441-443) whose main faces are positioned against each other and are interconnected.

Abstract: A cathode ray tube includes an electron gun having a beam-shaping portion (20) for generating electron beams (7-9), a prefocusing system (30) of electrodes (31, 32) across which a prefocusing voltage is supplied during operation so as to form an electron-optical prefocusing lens, and a main lens system (40) of electrodes (32, 41) across which a main lens voltage is applied during operation so as to form an electron-optical main lens. The electrodes (31, 32, 41) are provided with securing means (48) for connection to an insulating supporting body (47) and with apertures (16) for passing the electron beams (7-9). Electrode (32) protrudes toward electrode (31) in such a way that the mutual distance (l2) between the two electrodes at the location of the apertures (16) therein is smaller than their mutual distance (l1) at the location of their respective securing means (48).

Abstract: A cathode ray tube having an electron gun for relatively low beam currents (less than 1 mA) is shown. The electron gun has a G1 and a G2 electrode. The voltage difference between these electrodes is more than 800 Volt and the electrical field strength E.sub.12 between said electrodes is more than 4 keV/mm. An improvement in spot size is thereby obtained.

Abstract: Picture display device comprising a display tube with an electron gun having a hollow tubular structure with an inner surface on which a resistance structure of a material having a high electrical resistance is provided, which structure constitutes a focusing lens. The resistance structure is connected to at least two axially spaced electric contacts for connecting an anode voltage and at least one electric contact located in between for applying a focusing voltage. An electrode means of low-ohmic material for controlling the focusing lens by means of a dynamic correction signal is arranged in the region of the connection for the focusing voltage. Upon energization, the low-ohmic electrode means particularly exercises a non-rotationally symmetrical effect on the electron beam.

Abstract: A display tube comprising an electron gun having a beam-shaping part and a focusing structure. The focusing structure comprises an elongate hollow structure with a high-ohmic resistive layer provided on the inner and/or outer surface and comprises means for forming a non-rotationally symmetrical lens element in the area of the focusing structure. This may be a structure generating an electric multipole (for example, dipole or quadrupole) which may be incorporated particularly in the high-ohmic resistive layer.