Abstract: An in-line electron gun for a color picture tube has an accelerating electrode portion separated into two or three electrodes in a triode, in which a voltage supplied to respective electrodes is varied and an asymmetrical hole is formed in at least one among the electrodes to form an additional asymmetric lens, thereby preventing degradation of a focus characteristic caused by an abrupt increase of a diverging angle of electron beam in a high current region, degradation in the vertical electron beam due to an influence of a magnetic field of a deflection yoke, change of focusing force induced by voltage variation of a first accelerating/focusing electrode, and degradation of the electron beam owing to collision/repulsion among electrons in the electron beam.

Abstract: In-line electron guns for color picture tube improving the resolution of the color picture tube. The guns not only exhibit the special quality of a large aperture of lens but also achieve the desired mechanical strength of electrodes by arranging .OR right.-shaped inner electrode plates in the envelope electrodes respectively. Each of first and second accelerating/focusing electrodes for focusing three electron beams of the electron beam sources on the phosphor screen includes an envelope electrode and an electrostatic field control electrode placed in the envelope electrode. The envelope electrode includes a predetermined length of hollow envelope part and a predetermined width of rim part extending from an edge of the hollow envelope part. The electrostatic field control electrode includes a plate electrode sided by predetermined width of blades at opposed sides thereof. This blade sided plate electrode is holed at its center so as to have a center beam passing opening.

Abstract: A laser welding method for preparation of an electron gun of a color cathode-ray tub. This laser welding comprises the steps of forming a coining part on an evaporation section of a weld zone of an upper part to be welded to a lower part, and focusing a laser beam on a bottom surface of the coining part. This coining part has a diameter larger than a diameter of the evaporation section and is formed in such a manner that it permits the weld zone of the upper part to have a predetermined thickness. In accordance with this laser welding, a weld nugget formed at the juncture between the upper and lower parts by is enlarged in its diameter and, as a result, increases the weld strength between the upper and lower parts. The coining part has a bottom surface of a plane surface or a curved surface. This laser welding can weld all of the parts of the electron gun even when an upper part to be welded to a lower part is thicker than the lower part and permit the welding condition to be easily determined.