Charge image charge transfer cathode ray tube having a scan expansion electron lens system and collimation electrode means

Claim 1

A charge image charge transfer cathode ray tube, comprising: an envelope having a fluorescent screen at one end and cathode means at another end for producing a writing electron beam of high velocity electrons directed toward said screen; deflection means disposed along a tube axis of said envelope and including elements for deflecting said electron beam in mutually perpendicular directions; first quadrupole lens means disposed along said tube axis and positioned before said deflection means for focusing said electron beam in mutually perpendicular directions and second quadrupole lens means disposed along said tube axis and positioned between said elements of said deflection means for amplifying the electron beam deflection while maintaining the electon beam velocity constant; transmission mesh storage target means disposed adjacent said fluorescent screen including mesh target electrode means and storage dielectric means provided on said mesh target electrode means leaving open the mesh apertures, said writing beam adapted to bombard said storage dielectric means at voltages at which the secondary emission ratio of the dielectric means is greater than unity to write a charge image on said dielectric means; flood gun means adjacent said deflection means for providing a flood gun beam of low velocity flood electrons over said target means; collector electrode means disposed adjacent said target means for collecting secondary electrons emitted by said storage dielectric means; and collimating electrode means provided along said envelope between said flood gun means and said collector electrode means thereby causing the flood electrons to be distributed uniformly over said target means and to engage said target means or pass through apertures thereof at a substantially normal direction thereto.