Electron excited fluorescent display device including screen with rare earth phosphor exhibiting sublinear current density-emission luminance characteristics

Claim 1

An electron excited fluorescent display device including a fluorescent screen, and comprising, as the main part of the fluorescent screen, a rare earth yellow to red emitting phosphor represented by the following general formula: (Ln.sub.1-x-y,Eu.sub.x,Ce.sub.y).sub.2 O.sub.2 S in which Ln is at least one of yttrium, gadolinium, lanthanum and luetetium, x is a number satisfying 10 -4 ≦x≦9×10 -2 , and y is a number satisfying 10 -6 ≦y≦2×10 -3 , and exhibiting sublinear current density-emission luminance characteristics when current density of an excitation electron beam is increased, said electron excited fluorescent display device being a current modulation type multi-color cathode ray tube provided with at least one current modulation electron gun for changing the current density of the electron beam emitted therefrom, a non-pattern fluorescent screen positioned in an advancing direction of said electron beam so as to stand face to face with said current modulation electron gun, and a deflecting coil or coils for generating a magnetic field in a direction normal to the advancing direction of said electron beam, deflecting said electron beam, and causing the entire surface of said non-pattern fluorescent screen to be excited by said electron beam and to emit light, and said non-pattern fluorescent screen comprising a yellow to red emitting phosphor as defined above exhibiting the sublinear current density-emission luminance characteristics when the current density of said electron beam is increased, and a phosphor exhibiting an emission color different from said yellow to red emitting phosphor and exhibiting superlinear or linear current density-emission luminance characteristics when the current density of said electron beam is increased.