| 摘要 |
An electron gun of a cathode ray tube includes an electron beam generating unit and a main lens unit. The electron beam generating unit includes a cathode, a first grid electrode and a second grid electrode, and the main lens unit is formed of plural electrode members and a final accelerating electrode disposed downstream thereof and supplied with a high voltage. A final main lens is formed between the final accelerating electrode and one of the electrode members adjacent thereto. An electrostatic quadrupole lens is formed in a first space between adjacent ones of the electrode members, one of which is supplied with a first focus voltage of a fixed value, another of which is supplied with a second focus voltage synchronized with electron beam deflection, wherein the first and second focus voltages are higher than a second grid electrode voltage. The quadrupole lens focuses the electron beams horizontally and vertically and diverges them horizontally and vertically depending upon which is the higher of the first and second focus voltages. A third electrostatic lens is disposed between the final main lens and the quadrupole lens and formed in a second space between adjacent ones of the electrode members, one of which is supplied with the first focus voltage, and another of which is supplied with the second focus voltage, and the third electrostatic lens decreases horizontal and vertical focusing actions on the electron beams with increasing electron beam deflection.
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