Electrode lens potential arrangement for a post-acceleration picture tube

Claim 2

An electron gun for a post-acceleration picture tube which comprises a phosphor screen, means for applying a voltage to said phosphor screen, funnel anode electrode means, means for applying to said anode electrode means a voltage which is lower than the voltage applied to said phosphor screen, a shadow-mask, means for applying to said shadow-mask a voltage similar to the voltage applied to said anode electrode means; said electron gun comprising a cathode for projecting an electron beam, first, second and third electrodes arranged in series along the direction of travel of the electron beam projecting from said cathode, means for applying to said first electrode a voltage which is lower than the voltage applied to said anode electrode means and for actuating said first electrode as a focusing electrode, said first electrode being disposed nearest to said cathode of said three electrodes, means for applying to said second electrode a voltage which is substantially equivalent in its magnitude to the voltage applied to the phosphor screen, said second electrode being disposed in the middle of said three electrodes, and means for applying to said third electrode a voltage which is substantially equivalent in its magnitude to the voltage applied to the anode electrode means, said third electrode being disposed as the remotest electrode from said cathode of said three electrodes, said first, second, and third electrodes to which said voltages are applied by the voltage applying means forming a main electron lens responsive to an electrostatic field produced therebetween.

Claim 3

An electron gun for a post-acceleration picture tube which comprises a phosphor screen, means for applying a voltage to said phosphor screen, funnel anode electrode means, means for applying to said anode electrode means a voltage which is lower than the voltage applied to said phosphor screen, a shadow-mask, means for applying to said shadow-mask a voltage which approximates in its magnitude said voltage applied to said anode electrode means; said electron gun comprising a cathode for projecting an electron beam, first, second, and third electrodes arranged in series along the direction of travel of the electron beam projecting from said cathode, means for applying to said first electrode a voltage which is lower than the voltage applied to said anode electrode means and for actuating said first electrode as a focusing electrode, said first electrode being disposed nearest to said cathode of said three electrodes, means for applying to said second electrode a voltage which is substantially equivalent in its magnitude to the voltage applied to said phosphor screen, said second electrode being disposed in the middle of said three electrodes, and means for applying to said third electrode a voltage which is substantially equivalent in its maGnitude to the voltage applied to said shadow-mask, said third electrode being the electrode which is disposed remotest from said cathode of said three electrodes, said first, second, and third electrodes to which said voltages are applied by the voltage applying means forming a main electron lens responsive to an electrostatic field produced therebetween.

Claim 4

An electron gun for a post-acceleration picture tube which comprises a phosphor screen, means for applying a voltage to said phosphor screen, funnel anode electrode means, means for applying to said anode electrode means a voltage which is lower than the voltage applied to said phosphor screen, a shadow-mask, means for applying to said shadow-mask a voltage which approximates in its magnitude said voltage applied to said anode electrode means; said electron gun comprising a cathode for projecting an electron beam, first, second, and third electrodes arranged in series along the direction of travel of the electron beam projecting from said cathode, means for applying to said first electrode a voltage which is lower than the voltage applied to said anode electrode means and for actuating said first electrode as a focusing electrode, said first electrode being disposed nearest to said cathode of said three electrodes, means for applying to said second electrode a voltage which is substantially equivalent in its magnitude to the voltage applied to said phosphor screen, said second electrode being disposed in the middle of said three electrodes, and means for applying to said third electrode a voltage which is substantially equivalent in its maGnitude to the voltage applied to said shadow-mask, said third electrode being the electrode which is disposed remotest from said cathode of said three electrodes, said first, second, and third electrodes to which said voltages are applied by the voltage applying means forming a main electron lens responsive to an electrostatic field produced therebetween.

Claim 5

The electron gun as defined in claim 1 wherein said voltage applied to said third electrode is substantially half the voltage applied to said second electrode.

Claim 6

The electron gun as defined in claim 1 wherein said first, second, and third electrodes have the same diameter.

Claim 7

The electron gun as defined in claim 4 wherein the end portion of said second electrode opposite to the end portion of said first electrode has a diameter which is smaller than said same diameter, and a part of the end portion of said second electrode is inserted into the end portion of said first electrode.