Abstract: A cathode for an electron tube and a method of preparing the same are provided. The cathode includes a base metal and an electron emissive material layer attached to the base metal. A surface roughness, which is measured from the distance between a highest point and a lowest point of the surface of the electron emissive material layer, is controlled to be no greater than 8 ?m. By controlling the sizes of particles and pores constituting the electron emissive material layer to be uniform and controlling the density and porosity of the electron emissive material layer, the cathode is improved in compactness and surface evenness compared to a cathode prepared according to a spraying method. Accordingly, shrinking of the cathode during operation can be prevented, and the distance between the cathode and a G1 (first grid) electrode can be maintained uniform, so that the life of the cathode can be greatly extended, and a stable electron emission characteristic can be realized.

Abstract: A cathode for an electron tube and a method of preparing the same are provided. The cathode includes a base metal and an electron emissive material layer attached to the base metal. A surface roughness, which is measured from the distance between a highest point and a lowest point of the surface of the electron emissive material layer, is controlled to be no greater than 8 &mgr;m. By controlling the sizes of particles and pores constituting the electron emissive material layer to be uniform and controlling the density and porosity of the electron emissive material layer, the cathode is improved in compactness and surface evenness compared to a cathode prepared according to a spraying method. Accordingly, shrinking of the cathode during operation can be prevented, and the distance between the cathode and a G1 (first grid) electrode can be maintained uniform, so that the life of the cathode can be greatly extended, and a stable electron emission characteristic can be realized.

Abstract: A multi-step focusing type electron gun is disclosed which includes a cathode, electrodes G1 and G2, and electrodes G3, G4, G5, G6, G7, and G8 for forming two unipotential auxiliary lenses and a bipotential major lens in the main lens, characterized in that the electrodes G4, G5, G6, G7 are so constituted as to satisfy some specific formulas. The electron gun can reduce the size of the beam spot and the size of the halo formed around the beam spot. Further the electron gun improves the spherical aberration, and provides the flexibility in designing for different purposes, as well as improving the image quality on the screen.

Abstract: An electron gun for CRTs comprising multi-lens system is disclosed, wherein the rear part of the third electrode (16) forming the lens radius D3 is deeply recessed axialwise by interval H1 to provide the longer lens radius D3' equaling the lens radius D4 the fourth electrode (18) and the sixth electrode (22) is positioned inside the fifth electrode (20), thereby providing the main lens system forming the regions in the form of divergence-convergence-divergence-convergence-divergence-convergence- divergence, said sixth electrode (22) forming the subordinate lens against the main lens formed between the fifth electrode (20) and the seventh electrode (24), said interval H1 being limited within 0.5 to 0.54 of the lens radius D4of the fourth electrode.

Abstract: The present invention relates to focusing electrodes of an electron gun for use in a color television cathode ray tube and, more particularly, to focusing electrodes, wherein a third focusing electrode is united with a long extension member, comprising an elongated tube, an attenuation tube and another elongated tube, to which the third focusing electorde is electrically connected and a fourth focusing electrode is united with a short extension member, comprising an elongated tube and an attenuation tube, to which the fourth focusing electrode is electrically connected.The said improved structure is provided to reduce a local voltage difference as well as an influence from high potential field in the neck region so that a good convergence can be obtained and to offset an astigmatism so that a better picture on the screen can be provided.