Color picture tube having inline electron gun with focus adjustement means

Abstract From the Canadian patent

A color picture tube has a viewing screen and an electron gun for generating and directing three inline electron beams, a center beam and two side beams toward the screen. The gun includes electrodes that form three focus lenses. A first lens is located in a beam-forming region of the gun. A second lens includes at least one electrode for providing asymmetrically-shaped beams to a third lens. The third lens is a common main focus lens for all three beams. The improvement comprises one of the electrodes of the third lens being shaped to provide a major amount of focus correction for each individual electron beam and, the one electrode of the second lens including means for providing the …