Cathode ray tube including an electron gun having specific relation between axial length of focus electrode and lens-screen distance

摘要

A cathode ray tube has an anode of a large-diameter cylinder portion on its phosphor screen side and a small-diameter cylinder portion on its cathode side connected together, and a focus electrode formed of a large-diameter cylinder portion of a diameter larger than that of the small-diameter cylinder portion of the anode and a small-diameter cylinder portion having a diameter smaller than that of the small-diameter cylinder portion of the anode, the large-diameter and small-diameter cylinder portions being connected together. The large-diameter cylinder portion of the focus electrode is disposed concentrically within the large-diameter cylinder portion of the anode. The anode and a first electrode facing a cathode side end of the focus electrode are electrically connected together within the cathode ray tube. The following relationship is satisfied: -LP+184.9>=LG4>=0.0004 LP3-0.1571 LP2+21.006 LP-922.41, LP>=131.7, where LG4 (mm) is an axial length of the focus electrode, and LP (mm) is a distance from a phosphor screen side end of the focus electrode to a center of the phosphor screen.