Color cathode-ray tube with plural cathodes and three common grids each having same plurality of beam-defining apertures

Claim 1

A cathode-ray tube having an electron gun for producing a plurality of electron beams, a luminescent screen positioned to intercept said beams, a color-selecting electrode between the electron gun and screen and spaced from the luminescent screen in a plane in which the various electron beams are converged, the electron gun comprising a separate cathode for each electron beam, a common first grid provided with an aperture for each beam, a common second grid which serves as an accelerating electrode and is provided with an aperture for each beam, a common third grid having an aperture for each beam and a dimension at the aperture in the direction of the axis of the gun which is less than 4 mm. said third grid being provided on the side remote from the second grid with an annular elevation having a diameter which is greater than the enveloping area of the apertures and substantially equal to the diameter of a fourth grid positioned adjacent the third grid, said fourth grid having a circular cross section, the section of the fourth grid being smaller on the side of the third grid than on the other side, and a common fifth electrode of substantially circular-cylindrical shape, the apertures in the third grid lying substantially in a plane passing through the axis of the gun.