Beam scanning device producing a horizontally uniform electron beam

Abstract

A flat cathode-ray tube wherein a horizontally uniform sheet-like electron beam is vertically deflected and modulated with a video signal, with the modulated electron beam irradiating a portion of a phosphor screen, includes a modulation electrode assembly arranged by n electrode groups, each consisting of at least one first electrode group and at least one second electrode group, the first electrode group having vertically elongated stripe electrodes, each having one or n (n is an integer of 2 or more) openings or slits corresponding to each pel and which are aligned in the horizontal direction on at least one plane such that all openings are equidistantly formed, the second electrode group having the same construction as the first electrode group or being arranged such that vertically elongated stripe electrodes, each having n openings or slits corresponding to n pels along the horizontal direction are aligned on at least one plane to equidistantly form the openings along the horizontal direction, all the openings of the n electrode groups being aligned along an electron beam propagation direction and the n electrode groups being offset by 1/n the pitch along the horizontal direction, wherein the sheet-like electron beam is generated toward the vertical scanning surface of the phosphor screen and is then deflected substantially normal to the phosphor screen, or alternatively, the beam is generated perpendicular to the phosphor screen, and the electron beam can be vertically deflected and then modulated, and vice versa.