Beam index color cathode ray tube

摘要

A beam index color cathode ray tube has index stripes spaced apart across a run-in area of the screen and which have a pitch substantially equal to the pitch of index stripes in an image area. A plurality of the index stripes in the run-in area generate an index signal as an electron beam scans them. An index stripe is omitted from the portion of the run-in area nearest the boundary with the image area to provide a characteristic to the index signal which permits generation of a trigger signal to preset color control circuits to a known condition as the electron beam enters the image area. A gating circuit blocks trigger signals which may be generated during scanning of the image area.