Colour CRT for TV set - has a phosphor layer on the inner side of the screen consisting of primary colour triplets, red, green and blue

The CRT is fitted with a shadow mask complete with a supporting frame. Centres of phosphor elements forming the colour triplets (G, H, I) form equilateral triangles, whose on side is parallel to the screen horizontal axis; centres (M) of the equilateral triangles (G, H, I) are also centres of triangles whose apices (D, E, F) are middle points of sides of further triangles whose apices (A, B, C) are centres of corresponding focal spots of the electron beams. The shapes of the triangles ABC carry according to their position on the screen of the CRT and the angles at which the electron beams pass through the shadow mask.