Post acceleration type cathode ray tube with perforated hollow collector electrode adjacent shadow mask

Claim 1

In a post acceleration type cathode ray tube of the class comprising a panel, a fluorescent screen coated on the inner surface of said panel, a funnel, an auxiliary electrode coated on the inner surface of said funnel, a neck, at least one electron gun positioned within said neck, said panel, funnel and neck cooperating to form a sealed envelope, an electrode having perforations for transmitting an electron beam maintained at a potential below the post acceleration potential and positioned in front of said fluorescent screen, and a hollow secondary electron collector electrode positioned within the envelope and having open ends, said collector electrode forming an enclosure surrounding the path of the electron beam directed toward the fluorescent screen from the electron gun, the improvement in which said secondary electron collector electrode is constructed to have perforations for transmitting a portion of the secondary electrons generated by other electrodes of said tube to said auxiliary electrode.