Race Differences in Income

A single gun cathode-ray tube for the display of color television images including a separate cathode for each electron beam and common first, second, third and fourth grids, each having apertures for each beam. The distance between successive centers of the apertures in the third grid is less than 7 mms. and the dimension of the third grid at the apertures in the direction of the axis of the gun is not more than 4 mms.