Color picture tube shadow mask having improved mask aperture pattern

Abstract

A color picture tube has a rectangular shadow mask mounted therein in spaced relation to a viewing screen. A major axis passes through the center of the mask and parallels the long sides thereof and a minor axis passes through the center of the mask and parallels the short sides thereof. The mask has an aperture array that includes slit-shaped apertures aligned in columns that essentially parallel the minor axis and end at a border of the aperture array. Adjacent apertures in each column are separated by tie bars in the mask that are longitudinally offset from column to adjacent column. The spacing from tie bar to tie bar in a column is the tie bar pitch at a location on the mask. A first set of the aperture columns, comprising every other column, has full length ultimate apertures at least at one end thereof, and a second set of the aperture columns, comprising every other column not in the first set, has partial length ultimate apertures at least at one end thereof. The ultimate apertures of all of the aperture columns end on smooth curved border lines. The tie bar pitch of the columns decreases from the center of the mask to the short sides thereof, with the tie bar pitch in the region of the short sides of the mask being optimized to minimize moire at the sides of the screen during tube operation. The tie bar pitch along each column varies also from the center of the mask to the long sides of the mask.