Color cathode ray tube apparatus

A color cathode ray tube apparatus comprising:

• a screen;
• an electron gun which generates an electron beam and in which a main lens for accelerating and focusing the electron beam toward said screen is formed;
• and
• a deflecting yoke which scans the electron beam emitted from said electron gun in horizontal and vertical directions,
• wherein the main lens is formed of a focus electrode, a plurality of intermediate electrodes, and an anode electrode each of which has an electron beam hole and which are arranged along a traveling direction of the electron beam,
• at least one of the intermediate electrodes has a disk-like shape,
• the disk-like intermediate electrode is arranged at a position which satisfies (distance between focus electrode and disk-like intermediate electrode)≠(distance between disk-like intermediate electrode and anode electrode),
• the disk-like intermediate electrode has a non-circular electron beam hole,
• voltages to be applied to the respective intermediate electrodes are determined at values between a voltage of the focus electrode and a voltage of the anode electrode, the voltage to be applied to an intermediate electrode arranged to oppose the focus electrode is lower than the voltages to be applied to remaining intermediate electrodes, and the voltages to be applied to the intermediate electrodes sequentially increase in the traveling direction of the electron beam,
• the voltage to be applied to the disk-like intermediate electrode is applied such that a potential distribution on an axis extending through the electron beam hole in a certain deflecting amount is substantially equivalent to that obtained when the disk-like intermediate electrode is not provided,
• a value of {(voltage of disk-like intermediate electrode)−(voltage of focus electrode)}/{(voltage of anode)−(voltage of focus electrode)} changes in synchronism with an increase in a deflecting amount of the electron beam, and
• as the deflecting amount of the deflecting beam deflected by said deflecting yoke increases, a focusing power in the vertical direction of the main lens formed of the focus electrode to anode electrode becomes smaller than that in the horizontal direction.