Patent ID: 6515410
Filing Date: 2003-02-04
Classification: H01J

Abstract:
A color cathode ray tube including an evacuated envelope constituted of a panel which forms a phosphor screen on an inner surface thereof, a neck which houses an electron gun and a funnel which connects the panel and the neck, whereinthe panel has an approximately rectangular screen which has a long axis in the X direction and a short axis in the Y direction and the diagonal effective diameter of the screen is set to approximately 51 cm, the electron gun housed in the neck includes an electron beam generating part which is made of a cathode and first electrode and second electrode which are arranged in sequence from the cathode to the screen side, and a focusing electrode and an anode electrode which are arranged in sequence at the screen side of the electron beam generating part, assuming the equivalent radius of curvature in the X direction of the inner surface of the panel as Rix and the equivalent radius of curvature in the Y direction of the inner surface of the panel as Riy, the distance Lm between the cathode and a screen-side end portion of the focusing electrode which constitutes the main lens is set to a following value. 37&lE;Lm&lE;37+23.4âˆ’(Rixâˆ’{square root over ( )}((Rixâˆ’Riy+{square root over ( )}(Riy2âˆ’1502))2âˆ’2002)).