Cathode-ray tube with variable energy of beam electrons

Claim 1

A cathode-ray tube with variable electron energy, comprising: a glass bulb having an axis and front and rear portions; a screen located in said front portion and being coated with a luminophore whose luminescence color varies with the change of the electron-beam energy impinging upon said screen; an electron source arranged in said rear portion and emitting a diverging electron beam; electron accelerating means arranged in said bulb behind said source, downstream of the diverging beam; first deviation means for the diverging beam, arranged behind said accelerating means, downstream of the diverging beam, to form symbols on said screen; means for focusing the diverging beam with the variable electron energy, located downstream of the beam, behind said first deviation means; two axisymmetrical electrodes serving as an electrostatic lens for said focusing means, mounted with a gap therebetween along the bulb axis; the first one of said electrodes being downstream of the focused beam and electrically connected with said accelerating means; the second of said electrodes being electrically connected with said screen; an axisymmetrical magnetic lens for said focusing means, located behind said electrostatic lens, downstream of the focused beam, and having a magnetic field intensity that is constant in time, and being arranged beyond said bulb; second deviation means for the focused beam, arranged downstream of that beam, behind said focusing means, to move the symbols formed by said first deviation means along said screen; a D.C. voltage source connected with said accelerating means for creating a potential on said first electrode; an A.C. voltage source connected with said screen for creating a potential on said second electrode, which latter potential is different from the potential of said first electrode, so that while altering the potential of said screen, and of said second electrode, the change of optical force formed by said electrodes is automatically made up for a reverse conjugated alteration of the optical force of said magnetic lens, so that under two values of the potential of said screen, consecutively changed in time, automatically ensures simultaneously both the invariable focusing of lines forming the symbols on said screen, and the invariable size of the symbols formed by said first deviation means; and other power sources electrically connected with said electron source, said deviation means and said magnetic lens, respectively; said electron source, said accelerating means, said focusing means and said deviation means being arranged along the bulb axis.