beams are formed in the flat electrode 5 1 provided in the g 3 electrode 5 in the horizontal direction in line gun arrangement plane x u2014 x the flat electrode 6 1 provided in the g 4 electrode 6 has a central beam passing hole 6 g at its center and the side electron beam passing holes 6 r and 6 b are formed by the inner wall of the g 4 electrode 6 and each part of the cutaways on both sides in the x u2014 x direction of the flat electrode 6 1 the mutually facing openings of the g 3 electrode 5 and g 4 electrode 6 have the same shape the outside diameter t mm of the neck 63 is 24 3 mm the beam spacing s mm between the central axes 57 58 and 59 of adjacent electron beams entering the main lens is 4 75 mm and the diameter d mm in the direction perpendicular to the arrangement of the three electron beams of the openings of the g 3 electrode 5 and g 4 electrode 6 serving as the main lens diameter is 5 5 mm for these dimension the following expression is obtained therefore the outside diameter t of the neck glass satisfies the following inequality and the dimension s is 4 75 mm which is larger than 4 1 mm therefore in this case it is.