| 摘要 |
<p>"Colour television display tube with coma correction." Colour television display tube comprising an electron gun system (5) in an evacuated envelope for generating three electron beams whose axes are co-planar and which converge on a display screen (10) provided on a wall of the envelope and are deflected in the operative display tube across said display screen into two orthogonal directions. The electron gun system (5` has correction elements for causing the rasters scanned on the display screen by the electron beams to coincide as much as possible, which correction elements comprise, for example, annular elements (34) of a material having a high magnetic permeability which are positioned around the two outer beams. In addition a further correction element (38, 38", 38",) of a material having a high magnetic permeability is provided around the central beam in a position located further to the rear in order to correct field coma errors at the ends of the vertical axis and in the corners to an equal extent. The further element is preferably positioned in, or in front of the area of the focusing gap of the electron gun. Fig. 6d.</p> |
